Automobile Shredder Residue - The Problem and Potential SolutionsAUTOMOBILE SHREDDER RESIDUE - THE PROBLEM AND POTENTIAL SOLUTIONS
An Overview of the Industry and Problem and a Review of Potential Methods for Disposal
CMP REPORT NO. 90-1”
January 1990
Prepared by
Robert J. Schmitt Manager of Technical Projects Center for Materials Production
Prepared for
4400 Fifth Avenue Pittsburgh, PA 15213-2683
Joseph E. Goodwill CMP Director
,
Legal Notice
T h i s r e p o r t w a s p repared by t h e o rgan iza t ion named below a s an account of work sponsored by t h e Electric Power Research I n s t i t u t e , Inc . (EPRI). Nei ther EPRI, m e m b e r s of EPRI, t h e organiza t ion names below, nor any person a c t i n g on behal f of any of them: {a i m k e s any wilrzanty, express or implied, w i t h r e spec t t o t h e use of any information, appara tus , method, o r process d i s c l o s e d i n t h i s r epor t or t h a t such u s e may not i n f r i n g e p r i v a t e l y owned r i g h t s ; o r (b) assumes any l i a b i l i t y w i t h r e spec t t o the use o f , or, f o r damages r e s u l t i n g from t h e use o f , any information, apparatus, method, o r process d i s c l o s e d i n t h i s r e p o r t .
Prepared by Robert J. Schmitt, CMP Manager of Technical P r o j e c t s
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PROJECT OBJECTIVE
CMP PERSPECTIVE
PROJECT BACKGROUND
There are about 200 automotive shredders operating in the USA and they process millions of old cars and trucks each year. Most automobile shredders are powered by electrical motors ranging from 1000 to 6000 horsepower. Electrical consumption is reported to be in the range of 15 to 25 kWh per ton. Shredding of vehicles produces about 2 . 5 to 3 million tons of automobile shredder residue or "auto-fluff" per year. Auto fluff is that portion of the shredded car that remains after the steel and nonferrous pie'ces are essentially removed and is comprised of rubber, plastic, fiber, glass, dirt and very small fragments of metal. Fluff is not considered a hazardous material at this time except in California, and thus is being disposed of primarily in landfills. Concern on the part of the auto shredder is that disposal costs are rising, landfills are closing and environmental regulations are becoming more restrictive. Consequently, the auto shredders believe they have about 2 to 5 years to find suitable alternatives to disposing of auto fluff in landfills or face possibly being shut down.
A study was undertaken to identify 1) processes presently available for disposing of auto fluff, 2 ) research underway on potential disposal methods, and 3) potential processes that require further research and development and that would benefit from collaborative support from industry and E P R I .
RESULTS
It is concluded from this study that if auto fluff were to be declared hazardous by all 50 states and/or EPA, chemical fixation methods are available to treat fluff to allow disposal in landfills. However, landfill costs are risifig
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and landfills are closing. Further, obtaining permits for new ones is becoming extremely difficult. disposal methods that can reduce the volume of fluff to be stabilized and/or take advantage of its high heat value should be developed. reviewed and include 1) chemical fixation and landfill; 2 ) screening to produce fuel and landfill cover; and 3) incineration technology such as the rotary kiln, fluidized bed burning, gasification, plasma melting and submerged arc melting. A l s o potential R&D projects are
Therefore, other
suggested.
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ABSTRACT
There are about 200 automotive shredders operating in the USA. Most automobile shredders are powered by electrical motors with electrical consumption reported to be in the range of 15 to 25 kWh per ton. Shredding of vehicles produces about 2.5 to 3 million tons of automobile shredder residue or "auto fluff" per year. Auto fluff essentially consists of rubber, plastic, fiber, glass and dirt. This study was undertaken by CMP to identify: 1) processes presently available for disposing of auto fluff, 2) research underway on potential disposal methods, and 3) potential processes that require further research and development and that would benefit from collaborative support from industry and E P R I . It is concluded from this study that if auto fluff were to be declared hazardous by all 50 states and/or EPA, chemical fixation methods are available to treat fluff to allow disposal in landfills. However, landfill costs are rising and landfills are closing. Further, obtaining permits for new ones is becoming extremely difficult. Therefore, other disposal methods that can reduce the volume of fluff to be stabilized and/or take advantage of its high heat value should be developed. The potential disposal methods are reviewed and include 1) chemical fixaton and landfill; 2) screening to produce fuel and landfill cover; and 3 ) incineration technology such as the rotary kiln, fluidized bed burning, gasification, plasma melting and submerged arc melting. Also potential R&D projects are suggested.
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CONTENTS
3 IMPORTANCE OF AUTOMOBILE SHREDDER INDUSTRY TO ELECTRIC UTILITY INDUSTRY
RESEARCH ON POSSIBLE DISPOSAL METHODS FOR AUTO SHREDDER RESIDUE
4
Chemical Fixation and Landfill Screening to Product Fuel and Landfill Cover Incineration Technology
Rotary Kiln Process Fluidized Bed Burning High Temperature Gasification Voest-Alpine HTV Process
Plasma Incineration Retech-P lasma Centri fuga1 React or Westinghouse Plasma Fired Cupola
Cookson GrOUp-deTOXTM Process Submerged Arc Melting
5 PROPOSED METHODS FOR DISPOSAL OF HAZARDOUS ASH FROM INCINERATION PROCESSES
Puremet Process Cookson Group deTOXTM Process
6 RELATED RESEARCH ACTIVITIES
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3-1
4-1
I
4-11
5-1
from
Power Generation From Automobile Shredder Waste Fuel: Characterization and System Feasibility
Development of a Fluidized Bed Combustion System for Auto Shredder Residue
Voest-Alpine High-Temperature Gasification Process
Page
4-2 Fluidized Bed Pilot Plant Schematic ASR Testing
4-3 Voest-Alpine High-Temperature Gasification
5-4 Schematic of Puremet Process For Copper Removal From Scrap
Waste Material Processing by deTOXTM Process
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5-6
Page
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Section 1 SUMMARY
About 200 automobile shredders are in operation throughout the USA. It is estimated that about ten million motor vehicles are retired each year and most of these old cars and trucks are recycled through auto shredders. Most automobile schredders are powered by electrical motors and power requirements range from 1000 hp (750 kW) to 6000 hp (4470 kW) depending upon size of unit. Electrical consumption reportedly is in the range of 15 to 25 kWh per ton. Shredding of vehicles produces about 2.5 to 3 million tons of automobile shredder residue or "auto fluff" per year. Auto fluff is that portion of the shredded automobile that remains after the steel and nonferrous pieces are essentially removed and is comprised of rubber, plastic,
has a relatively high heating value of about 5400 BTUs and represents a source of energy. Fluff is not considered a hazardous material at this time except in California and thus is being disposed of primarily in landfills. Reportedly, depending upon location in the USA, disposal costs can range from $12 to $100 per ton, not including shipping charges. Concern on the part of the auto shredder is that disposal costs are rising, landfills are closing and environmental regulations both on disposal of fluff and shredder operations are becoming more restrictive. The auto shredders believe they have about 2 to 5 years to find suitable alternatives to disposing of fluff in landfills or face possibly being shutdown.
fiber, glass, dirt and very small fragments of metal. It
The purpose of this report is to review information on processes presently available for disposing of fluff, discuss research underway on potential disposal methods where information is available and identify potential processes that require further research and development and
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could benefit from collaborative support from industry and EPRI . The potential disposal methods reviewed in the report include 1) chemical fixation and landfill; 2) screening to produce fuel and landfill cover; and 3 ) incineration technology including the rotary kiln, fluidized bed burning, gasification, plasma melting and submerged arc melting. Although incineration significantly reduces the volume and weight of fluff, processes such as the rotary kiln and fluidized bed produce a hazardous ash. However, the plasma and submerged arc processes can produce a vitrified slag which is most likely non-leachable. Methods for treating the ash from the rotary kiln or fluidized bed to render it suitable for a landfill such as hydrometallurgy and submerged arc furnace processing are also discussed..
It can be concluded from this. review that if auto fluff were to be declared hazardous by all 50 states and/or the EPA, chemical fixation methods are available to treat fluff to allow disposal in landfills. However, landfill costs are rising and landfills are closing and obtaining permits for new ones is becoming extremely difficult. Therefore, other methods that can reduce the volume of fluff to be processed and/or take advantage of its high heat value should be developed. represents a potential method whereby the energy value of fluff can be realized and at the same time the ash from combustion of fluff is made into a non-leachable slag. However, it appears that this process will require a large capital investment and requires being tied into a user for the gas produced and thus is particularly suited for a centrally operated unit where fluff is supplied from several shredders. Shredder operators, particularly the large processors, have expressed the desire for a process that they can install on site to process fluff on a continuing
The Voest-Alpine HTV gasification process
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basis and not have to store or transport this light weight material. It appears that a small plasma reactor could serve this need and it is recommended that R&D be conducted to develop such a process. The Retech plasma test unit installed at the D.O.E. R&D facility in Butte, Montana, represents a potential means to obtain an evaluation of plasma for disposing of fluff. EPRI/CMP is interested in a collaborative project with the shredder industry to evaluate plasma in this application.
Other potential areas for R&D support include fluidized bed burning of fluff and hydrometallurgy and submerged arc furnace processes for treatment of hazardous ash from incineration processes.
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AUTOMOBILE SHREDDER R E S I D U E PROBLEM
Scrap au tomobi l e s , a p p l i a n c e s , and o t h e r s tee l o b j e c t s such as s h e e t s and l i g h t s t r u c t u r a l s are p r o c e s s e d by t h e s tee l s h r e d d i n g i n d u s t r y t o produce a f ragmented s teel scrap f o r s a l e t o t he e lectr ic arc fu rnace steelmaker. O l d
au tomobi l e s and t r u c k s make up t h e largest p o r t i o n o f t h e s c r a p p r o c e s s e d and it i s estimated t h a t as many a s 8 t o 1 0
m i l l i o n cars and t r u c k s are shredded a n n u a l l y . sh redd ing , t i r e s , ba t te r ies , r a d i a t o r s , and g a s o l i n e t a n k s are u s u a l l y removed. A t t h e a u t o shredder, t he s c r a p m a t e r i a l i s fed t o a hammermill t y p e shredder which chops and tears t h e o l d au tomobi l e s i n t o small p i e c e s which are conveyed t h r o u g h a s o r t i n g sys tem (1). The s tee l o r f e r r o u s metal pieces are separated m a g n e t i c a l l y from t h e n o n f e r r o u s metals (aluminum, copper , e tc . ) and p i l e d f o r shipment t o s teel makers . referred t o as " f l u f f " i s c o l l e c t e d by cyc lone a i r s e p a r a t i o n . Although l imi t ed i n p r a c t i c e , some a u t o shredders u s e w e t s h r e d d i n g where water i s sprayed on t h e
s c r a p d u r i n g sh redd ing . T h i s i s done t o p r e v e n t e x p l o s i o n s from s o l v e n t s remain ing i n t h e au tomobi le , p o s s i b l y from o l d p a i n t c a n s l e f t i n t h e t r u n k . r e c y c l e d it picks up con taminan t s and r e p r e s e n t s a s e p a r a t e d i s p o s a l problem.
P r i o r t o
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The low d e n s i t y o r l i g h t material o f t e n
Although t h e w a t e r i s
About 200 au tomobi l e shredders are i n o p e r a t i o n th roughou t t h e USA p roduc ing about 2 . 5 t o 3 m i l l i o n t o n s o f a u t o f l u f f p e r y e a r . F l u f f i s comprised of p l a s t i c , g lass , rubbe r , f iber , some m e t a l and d i r t . A t yp ica l f l u f f composixion i s shown i n F i g u r e 2-1. aluminum, copper , cadmium, z i n c , i r o n , and e tc . The
p r e s e n c e o f hazardous metals such a s cadmium ( c o r r o s i o n r e s i s t a n t c o a t i n g f o r f a s t e n e r s and seat cove r c o l o r enhance r ) p r e s e n t p o t e n t i a l d i s p o s a l problems. F l u f f is not
The metals i n f l u f f v a r y b u t can be
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F i g u r e 2-1
T y p i c a l Auto F l u f f Composition*
Sponge & Foam - 19.3%
F a b r i c & B a t t i n g - 3 3 * 3 %
P l a s t i c s - 22.2%
Metal > 1 2 Mesh - - 6 e 1% (Copper-0 6%, Zinc-5 e 0 % )
Glass, Sand and D i r t - 19.1% (Lead-O.6%, AL-7% P l u s Metal < 1 2 Mesh and Iron-6%)
* P r o v i d e d by Puremet C o r p o r a t i o n
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considered a hazardous material by the U . S . Environmental Protection Agency (EPA) at this time except in California (cadmium restrictions) and thus is being disposed of primarily in landfills (2). - Reportedly, depending upon location in the USA, disposal costs can range from $12 to $100 per ton, not including shipping charges. The concern on the part of the auto shredder is that disposal costs are rising, landfills are closing and some states like Massachusetts are imposing stringent environmental regulations on shredder operations. For example, Massachusetts now requires that a shredder operator shut down if the fluff produced contains more than 7 percent of oily substances. Oily liquids come from the engine, transmission, differential and the antifreeze. Polychlorinated biphenyls (PCBs) probably coming from capacitors in appliances is also presenting serious problems for auto shredders. Residue containing greater than 50 ppm of PCBs can no longer be dumped in ordinary landfills but must be disposed of in special landfills or incinerators.
The fluff disposal picture is one of confusion for the auto shredder not knowing what direction government regulation will take in the future. However, auto shredders believe they have about 2 to 5 years to find suitable alternatives to disposing of fluff in landfills or face possibly being shut down.
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.
Sec t ion 3
IMPORTANCE O F AUTOMOBILE SHREDDER INDUSTRY TO ELECTRIC U T I L I T Y INDUSTRY
Most automobile shredders are powered by e lec t r ica l motors and power requi rements range from 1 0 0 0 hp (750 kW) t o 6 0 0 0
hp (4470 kW) depending upon s i z e o f u n i t ( 3 ) . Elec t r i ca l consumption r e p o r t e d l y i s i n t he range o f 15 t o 25 kWh p e r t o n . Because of s u r g e s i n shredder load ing when f e e d i n g a u t o bod ies , which can c o n t a i n engine b locks , o p e r a t o r s can a l s o i n c u r s i g n i f i c a n t demand charges. I n a d d i t i o n t o t h e
shredder, e lectr ic motors are used t o o p e r a t e conveyors and pneumatic systems. Blowers and s u c t i o n f a n s i n f l u f f s e p a r a t i o n s t a t i o n s can r e q u i r e i n excess of 2 0 0 hp ( 1 5 0 kW). A u x i l i a r y power requirements can be a s high as 1 0 0 0 hp
(750 kW). Thus, based on t h e aforementioned power requi rements a u t o shredders r e p r e s e n t a s i g n i f i c a n t u s e r of e l e c t r i c i t y .
The approximately 200 a u t o shredders i n t h e U.S. r e p o r t e d l y supply 1 2 t o 1 4 m i l l i o n t o n s p e r yea r of s c r a p t o the s t e e l i n d u s t r y which i s p r i m a r i l y consumed by the e lectr ic a r c furnace . Electric arc fu rnaces use e s s e n t i a l l y a 1 0 0 p e r c e n t s c r a p s teel charge. The e lec t r ica l energy r e q u i r e d t o make one t o n o f l i q u i d s teel i s about 500 kWh p e r t o n . Consequently, any impact on the a u t o shredder by federal r e g u l a t i o n s t h a t would reduce o r deter shredder o p e r a t i o n s would a l s o effect t h e supply and/or p r i c e of s c r a p f o r t h e
e lec t r ic a rc fu rnace . T h i s i n t u r n could have a n e g a t i v e impact on e lectr ical power consumption from b o t h t h e
shredder and e lectr ic arc fu rnace o p e r a t o r s t a n d p o i n t s .
Combustion of a u t o f i u f f i n a r o t a r y k i i n , f i u i d i z e d bed
combustor, g a s i f i c a t i o n p l a n t o r plasma p rocess , which w i l l
be described l a t e r i n t h i s r e p o r t , when coupled t o a waste heat b o i l e r can produce steam. The steam can be used t o p rov ide heat o r work f o r a s p e c i f i c purpose a t a cus tomer ' s
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1
plant, converted directly to electric power for use on site, or used to produce steam and electricity by cogeneration. The EnerGroup, Inc. in cooperation with the U.S. Department of Energy has proposed several conceptual energy recovery and conversion systems which are described in the D.0.E.- EnerGroup study entitled "Power Generation from Automobile Shredder Waste Fuel: Feasibility. (4) The study further provides capital and operating costs for proposed plants with varying sizes and configurations. scale, local disposal costs, electric power rates and availability of a steam customer.
Characterization and System
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RESEARCH ON POSSIBLE DISPOSAL METHODS
A number of organizations are working on developing novel methods for disposing of auto fluff o r adapting present refuse disposal processes to accommodate this waste product. The various methods can be classified in several categories described below. summary of specific research on various methods where information was available on the process.
Included under each category is a brief
Chemical Fixation and Landfill
Chemical fixation is a non-recovery alternative to secure landfills by which hazardous wastes can be converted into an environmentally non-hazardous material. currently one of several processes being used to treat electric arc furnace dust, which is classified as hazardous by EPA ( 5 ) . for many years for stabilizing mill tailings for mining backfill as well as a means of treating liquid wastes containing metallic hazardous products. Such a process could be used to stabilize auto fluff for disposal in a landfill. In this process the waste is mixed with another material to produce a chemical form that is more resistant to leaching when placed in the ground. Materials used for this process include asphalt, silicates, pozzalanic cements and portland cements. Reportedly, the Schnitzer Steel Shredding Company in Oakland, California, uses a polysilicate treatment (referred to as the "K20" process) to prevent hazardous metal leaching t h u s permitting disp~sal in a conventional class 3 landfill. estimated at $20 per ton. Companies actively promoting chemical fixation technology include Chemfix Technology, Inc. ( 6 ) , Stablex ( 7 ) , New Materials Technology ( 8 ) , and Bethlehem Steel (Superdetox) (2) .
This method is
Cost of this treatment is
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S c r e e n i n a t o Produce F u e l and L a n d f i l l Cover
The M i d w e s t Steel Company ( a u t o shredder) and the U n i v e r s i t y o f Wisconsin have developed a p r o c e s s whereby t h e y s e p a r a t e a u t o f l u f f i n t o two p r o d u c t s referred t o as " M i l l Cover" and " M i l l Fue l " , ( 1 0 ) - see Appendix A f o r de ta i led p r o c e s s d e s c r i p t i o n . M i l l c o v e r r e p o r t e d l y can be u s e d as a s u b s t i t u t e f o r t h e d a i l y s o i l c o v e r i n a l a n d f . i l 1 . M i l l
f u e l can either be s o l d o r consumed on s i t e t o g e n e r a t e steam, heat o r e l e c t r i c i t y . These p r o d u c t s are produced by
p r o c e s s i n g a u t o f l u f f t h r o u g h a r o t a r y s c r e e n trommel, compr ised o f two s e c t i o n s , one hav ing a s c r e e n w i t h 1 i n c h h o l e s and t h e o t h e r hav ing a s c r e e n w i t h 2 i n c h h o l e s . The
material p a s s i n g t h r o u g h t h e two s c r e e n s becomes t h e m i l l c o v e r and c o n t a i n s t he m a j o r i t y o f t h e r e c o v e r a b l e metals. However, t h e f e r r o u s and n o n f e r r o u s metals are either m a g n e t i c a l l y o r hand separated from the m i l l c o v e r . The
b a l a n c e o f t h e material o v e r 2 i n c h e s is t h e m i l l f u e l . The
d e v e l o p e r s o f t h e p r o c e s s claim t h a t there are many p o t e n t i a l markets f o r t h e m i l l f u e l w i t h paper m i l l s t h a t c u r r e n t l y b u r n sawdust and wood chips as prime c a n d i d a t e s . A l s o , it i s s u g g e s t e d t h a t t h e shredder o p e r a t o r may a l s o want t o c o n s i d e r u s i n g t he p r o d u c t a l o n g w i t h o t h e r f u e l s f o r c o g e n e r a t i o n which c o u l d h e l p r educe t h e o p e r a t i n g c o s t of t he o p e r a t i o n . I t i s a l s o claimed t h a t m i l l c o v e r o f f e r s a d v a n t a g e s o v e r s o i l as a d a i l y l a n d f i l l c o v e r and t h e y i n c l u d e better bar r ie r between waste and an ima l s , i n s e c t s and birds; a b s o r b s o d o r s bet ter t h u s less s m e l l more s t ab le s u r f a c e on which t o o p e r a t e vehicles and r e d u c e s b lowing d u s t . Al though, a t t h e p r e s e n t t i m e , m i l l c o v e r c o u l d be used on l a n d f i l l s e x c e p t i n California, future concern w n l ~ l d
be t h e haza rdous metals i n t h e less t h a n 2 i n c h mater ia l c o n c e n t r a t i n g and exceed ing any f u t u r e more s t r i n g e n t EPA r e q u i r e m e n t s .
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Incineration Technology
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The
Although there are no known commercial combustion plants for incinerating fluff in the USA, the EnerGroup study identified several generic types of combustion systems for fluff and are as follows:
1. Circulating fluidized beds 2. 3 . Gasification systems 4. High temperature slagging combustors 5. Traveling grate
Refractory lined and waterwall rotary k i l r , c~mbustors
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Of these methods, r o t a r y k i l n , f l u i d i z e d bed b u r n i n g and high t e m p e r a t u r e g a s i f i c a t i o n a p p e a r t o have t h e greatest p o t e n t i a l f o r s u c c e s s . Although n o t ment ioned i n t h e s t u d y , plasma and submerged arc m e l t i n g a l s o a p p e a r t o be p r o m i s i n g d i s p o s a l methods. i s p r o v i d e d below.
A brief review o f each o f these methods
Ro ta ry K i l n P r o c e s s
A s p a r t o f t h e EnerGroup s t u d y r e p o r t e d on above t h e y selected a r o t a r y k i l n t o t e s t t h e waste f u e l per formance of f l u f f ( 1 2 ) . - T h e r o t a t i n g a c t i o n o f a r o t a r y k i l n maximizes t h e exposure o f t he b u r n i n g mater ia l t o t he h o t combust ion gases and t h u s i s a h i g h l y e f f i c i e n t means f o r i n c i n e r a t i n g w a s t e . T h e t es t w a s conducted a t I n d u s t r o n i c s , I n c . i n South Windsor, Connec t i cu t , u s i n g a r o t a r y k i l n ra ted a t 2 m i l l i o n Btu p e r hour and equipped w i t h a secondary combustor, w a s t e heat b o i l e r , baghouse, and packed tower s c r u b b e r . Approximately 3.5 t o n s o f f l u f f were i n c i n e r a t e d o v e r a period o f three days and w a s comprised o f e q u a l volumes o f as-received f l u f f from e l e v e n d i f f e r e n t shredder
f a c i l i t i e s . The f l u f f m i x t u r e w a s fed i n t o t h e r o t a r y k i l n b y means o f a tapered auge r a t rates r a n g i n g from 200 t o more t h a n 4 0 0 lbs p e r hour .
The r e s u l t s o f t h e t e s t burn showed t h a t approx ima te ly 94 p e r c e n t o f t h e combus t ib l e s i n f l u f f were burned and t h e f l u f f r educed 55 p e r c e n t by weight and 80 p e r c e n t by volume. The r e s u l t i n g ash w a s r e p o r t e d t o have an average m o i s t u r e c o n t e n t o f 1 p e r c e n t , v o l a t i l e matter 6 p e r c e n t and c o n t a i n e d 25 p e r c e n t by weight o f i r o n . Chemical a n a l y s i s of an ash sample revealed s u b s t a n t i a l amounts of lead p r i m a r i l y as lead c h l o r i d e . Composite samples o f t h e ash w e r e a n a l y z e d u s i n g t h e EPA e x t r a c t i o n p r o c e d u r e t o x i c i t y t es t and w e r e shown t o exceed 5 . 0 mg/l f o r lead i n d i c a t i n g t h a t a s h from i n c i n e r a t i o n o f f l u f f h a s t he p o t e n t i a l t o be
c lass i f ied as a hazardous w a s t e . Other heavy m e t a l s w e r e
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present in the ash such as cadmium, chromium and barium but substantially below hazardous concentrations. Air emissions were monitored during the test burn with the exception of toxic organics and the report concludes that emissions from burning fluff can be controlled to within regulatory limits with existing technology.
Fluidized Bed Combustion
Based on results of extensive pilot plant testing Energy Products of Idaho (EPI) developed a unique fluidized bed combustion system for auto shredder residue. EPI has reported (13) - on the development work and preliminary results of environmental emissions testing, see Appendix C. A schematic of the pilot plant is shown in Figure 4-2, the fluidized bed contained nine square feet of bed area and 25 feet of freeboard above the fluidizing nozzles. In the process, fluff is fed through the feed tube and combustion is accomplished with a special fluidized cone arrangement. A particle size of less than six inches had to be maintained to prevent plugging of the feed tube. Combustion products then pass into a refractory cyclone and the ash captured can either be removed from the system or injected back into the fluidized combustor. part of the flow can be pulled through a heat exchanger and baghouse. Details of the process can be found in the aforementioned report.
Flue gases can exit the cyclone or
Three truckloads of fluff screened to three-inch minus were received and processed. Environmental testing was conducted for organic particulate and heavy metal emissions. this test program, continuous emission monitors recorded 0 2 ,
C o , So2 and Nox emissions. Limestone was added with the fuel on a continual basis because of high concentrations of glass and the potential for acid gas emissions.
During
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4-6
EPI r e p o r t s t h a t the emiss ion test data are p r o p r i e t a r y . The a u t h o r assumes t h e tests w e r e s u c c e s s f u l as t h e s t u d y has led t o a p r o p o s a l by EPI t o a major a u t o shredder t o des ign , b u i l d and o p e r a t e a 7 .5 megawatt e lectr ical power p l a n t u t i l i z i n g a f l u i d i z e d bed combustor t o burn a u t o f l u f f (f4). Repor t ed ly , p l a n t c a p a c i t y would be about 72,000 t o n s o f a u t o f l u f f p e r y e a r .
High Temperature G a s i f i c a t i o n P r o c e s s
Voest-Alpine has developed a p a t e n t e d p r o c e s s f o r high- t e m p e r a t u r e g a s i f i c a t i o n o f waste ( 1 5 ) . The p r o c e s s referred t o as HTV r e p o r t e d l y c o n v e r t s waste such as a u t o f l u f f i n t o c l e a n f u e l gas and a m i n e r a l i c s l ag g r a n u l a t e which can be used as a b u i l d i n g material. The p r o c e s s i s described i n de t a i l i n Appendix D and a brief d e s c r i p t i o n f o l l o w s . Fue l such as o i l and used s o l v e n t s are b u r n t i n a m u l t i - f u e l b u r n e r which m a i n t a i n s t h e t e m p e r a t u r e n e c e s s a r y f o r g a s i f i c a t i o n i n t h e r e a c t i o n chamber, F i g u r e 4-3. S o l i d and /o r a p a s t y waste material i s fed d i r e c t l y i n t o t h e
g a s i f i c a t i o n chamber and coke i s fed from t h e t o p i n t o t h e s h a f t . The h o t gases from t h e mul t i -bu rne r combust t h e waste and coke r e a c h i n g t e m p e r a t u r e s of about 3000F ( 1 6 0 0 C ) .
The s h e l l o f t h e r e a c t o r i s c o o l e d by f o r c e d c i r c u l a t i o n o f b o i l e r feed water. The combustion g a s e s l aden w i t h d u s t p a s s i n t o a cyc lone where most o f t h e d u s t p a r t i c l e s are s e p a r a t e d from t h e r a w gas and r e t u r n e d t o the r e a c t o r . I n t h e n e x t s tep t h e s e n s i b l e heat from t h e r a w gas i s exchanged w i t h c o o l i n g water t o produce h o t water o r steam. The gas i s t h e n p r o c e s s e d th rough a p u r i f i c a t i o n p l a n t where d u s t and c h l o r i d e and s u l f u r compounds a r e removed t o produce a c l e a n f u e l gas . T h e s l a g melted i n t h e combustion chamber f lows i n t o a water bath where it is c o o l e d and g r a n u l a t e d . A series of g a s i f i c a t i o n t r i a l s w i t h waste o i l and haza rdous waste have been conducted w i t h t h e HTV
-
I
industrial wastes; medical wastes; fuel oil containing I
mercury, cadmium and lead, etc., was processed. Reportedly, emission data revealed only traces of hydrocarbons and very low Nox levels in the HTV clean gas. The heavy metals in the slag were non-elutable. For specific details of the process contact Voest-Alpine.
Voest-Alpine has conducted tests (16) with their HTV- demonstration plant in Linz, Austria, to determine its suitability for processing auto fluff, see Appendix E. A
-
Based on one year's test operation of the HTV gasification pilot process, Voest-Alpine is presently offering this technology for sale worldwide.
PLASMA INC INERAT IGN
Plasma can produce temperatures in excess of 10,OOO°C and consequently has been considered as a means for processing hazardous waste. Although some research has been conducted on treating waste by heating with plasma apparently no work
4-9
has been done with auto fluff. Plasma can be applied in two ways to heat waste. With direct heating material is passed through the plasma flame, whereas with indirect heating the plasma is used to create a bath of molten material. excellent review of these methods and experiences with plasma to treat hazardous wastes has been prepared by Laurel J. Staley of the U.S. Environmental Protection Agency, Cincinnati, Ohio, and is entitled "Hazardous Waste Decontamination With Plasma Reactors." (17) - A copy of the paper is provided in Appendix F.
An
Reportedly, the indirect heating method is particularly suited for treating solid waste. The high temperature of the plasma combusts the waste material, volatilizing the organic waste contaminants, which are thermally destructed by the high temperatures. The molten material solidifies into a vitrified mass encapsulating any heavy metals present. The vitrified mass is non-leachable and thus suitable for disposal in a landfill.
Retech, Inc. of Ukiah, California, has developed an indirect plasma heating process referred to as the Plasma Centrifugal Reactor (PCR) which has potential for decomposing and stabilizing auto-fluff. Briefly, the PCR design incorporates a stationary plasma torch with a revolving tub inside a sealed reaction chamber (18). - The plasma torch heats the material producing a molten mass. The centrifugal force imposed upon the molten mass moves it to the outside of the chamber, where mixing of new feed material is accomplished, see Appendix G for details. The effluent gases are subject to a treatment system and a vitrified slag is produced.
The U.S. Department of Energy (DOE) has installed a Retech PCR unit adjacent to their magnetohydrodynamics facility in Butte, Montana, which is being operated by MSE/CDIF to
4-10
conduct tests for DOE and EPA. interested in conducting tests with auto fluff (19).
Reportedly, MSE/CDIF is -
The plasma-fired cupola developed by the Electric Power Research Institute and Westinghouse Electric Corporation has a plasma fired torch fitted to the bottom of the furnace (20). for iron melting independent of coke combustion primarily used in the conventional cupola. Since this development, the plasma technology group at Westinghouse has applied their developmental efforts pertaining to the plasma cupola to treatment of landfill material. date indicate that the plasma cupola is capable of vitrifying landfill type material without the need of elaborate pretreatment of the material. Westinghouse personnel envision that the plasma process would not only combust the fluff but produce a glassy slag encapsulating any hazardous metals and thus be suitable for disposal in a landfill.
In this application the plasma torch provides energy
The results of tests to-
Westinghouse has proposed to demonstrate the feasibility of processing automotive shredder residue in the plasma cupola located at the Westinghouse Environmental Service's Plasma Center in Madison, Pennsylvania. A two-heat test is proposed to determine the effects of material composition, feed methods and rates, and energy requirements. For more
information contact Dr. Shyam V. Digne at Westinghouse Electric Corporation, Madison, Pennsylvania.
Submerged Arc Melting
Cookson Group, PLC in the Q.K. reports that auto flilff can be combusted in a submerged arc furnace ( 2 1 ) . - proc'ess, which is called deTOXTM the heavy metals in the fluff are melted and encapsulated in the vitrified slag and
In the
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are non-leachable. Details of the process are covered in Section 5.
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S e c t i o n 5
PROPOSED METHODS FOR DISPOSAL OF HAZARDOUS ASH FROM I N C I N E R A T I O N PROCESSES
I n c i n e r a t i o n p r o c e s s e s such as r o t a r y k i l n s and f l u i d i z e d beds o f f e r promise f o r combusting a u t o f l u f f . However, t h e
a s h from the p r o c e s s can c o n t a i n heavy m e t a l s such as cadmium, l e a d , etc. and t h u s p o t e n t i a l l y can be declared a hazardous was te which would r e q u i r e f u r t h e r p r o c e s s i n g before b e i n g d i sposed of i n a l a n d f i l l .
S e v e r a l p r o c e s s e s appear p romis ing f o r t r e a t i n g a s h t o make i s s u i t a b l e f o r l a n d f i l l and a r e b r i e f l y described below.
Purement P rocess
Puremet Corpora t ion of Chat tanooga, Tennessee, has developed a h y d r o m e t a l l u r g i c a l p r o c e s s f o r t he removal of copper and o t h e r m e t a l s such as cadmium, z i n c , n i c k e l , e tc . , from s teel s c r a p . Puremet pe r sonne l believe the i r p r o c e s s would be
a p p l i c a b l e t o removal o f m e t a l s from a s h r e s u l t i n g from a u t o f l u f f combust ion.
A schemat i c of t h e p a t e n t e d p r o c e s s i s shown i n F i g u r e 5-4 as it p e r t a i n s t o removal of nonfe r rous metals from s teel s c r a p . B r i e f l y , i n t h i s p r o c e s s , s c r a p from shredded
automobi les , a p p l i a n c e s , etc. , from which t h e i r o n and s t ee l have been m a g n e t i c a l l y s e p a r a t e d i s fed i n t o a carbon s teel r e a c t i o n t a n k . A cuprous ammonium s u l f a t e s o l u t i o n i s added t o d i s s o l v e t h e copper , n i c k e l , z i n c , e tc . The s o l u t i o n i s recycled from the e l e c t r o w i n n i n g cells and the on ly heat added i s t h a t p i cked up i n t h e electrowinning process. T h e
r e a c t i o n t i m e v a r i e s depending upon the s c r a p mix; pu re copper d i s s o l v e s r a p i d l y . S t a i n l e s s steel s c r a p , aluminum and z i n c d ie c a s t i n g s a r e u n a f f e c t e d i n t h e p r o c e s s and a r e removed and s o l d f o r s c r a p .
5-1
Misc. scrap
Cuprous ammonium sulfate solution
zinc die castings
5-2
The metal rich solution then goes to the electrowinning cells where copper, zinc, nickel, etc. are recovered. Also, the metal rich solution can be sent to a refrigerated tank where copper salts are crystallized, then filtered and dried and can be sold to chemical firms. Puremet claims that all hazardous metals will be recovered and that the remaining residue will meet EPA requirements for disposal in a landfill.
With regard to handling auto fluff ash, Puremet envisions simply processing the ash through the process much like scrap. For further details, contact Mike Traynor or Paul Kruesi at Puremet.
The deTOXTM Process referred to earlier in Section 4 reportedly is not only suitable for combusting auto fluff and producing a vitrified product but is particularly suited for processing ash from incineration of auto fluff to produce a vitrified prodyct which encapsulates the heavy metals. The glass/ceramic type product produced can be converted to tiles, bricks, etc. The details of the process are described below.
Characteristics of deTOXTM
The deTOXTM process uses cold-top submerged arc melting to make a vitrified product in which dissolved heavy metals are encapsulated.
The characteristics of the process are:
1. Low heat losses and hence very high energy efficieacy and low operating costs.
5-3
2 . Use of other waste materials as fluxes. (Fine materials are pelletised or briquetted prior to feeding into the furnace units.)
3. Low volatilization of heavy metals and thus a high proportion of metal capture by vitrification.
4. Important (but not complete) destruction of toxic organics.
5. No burners used, so low gas evolution rates.
6. Suitability for connection of the exhaust duct to an adjacent incineration unit. Alternatively a miniature after-burner for destruction of distilled organics can be used.
7 , Low plan area and suitability for retro-fit to existing incineration units. fitted underneath an incinerator.)
(The deTOXTM unit may even be
8. Low capital costs. If process gases are not ducted into an incinerator, only a very small baghouse is needed.
9. The vitrified product is usable to make ceramics such as tiles or bricks. An alloy product stream is possible from some raw materials, thus optimizing value recovery.
10. Treatment rates of concentrated toxic dust from 500 to 6000 lbs per hour or more.
Applicability of deTOXTM (see Figure 5 - 5 )
The processing of shredded residues is intended to: i) recover valuable metals; ii) detoxify residuals.
5-4
5-5
deTOXTM can safely treat fine fractions (with high lead) resulting from screening shredder residues or, more important, the fume evolved during any burning processes. Each material (or mixture) is consumed completely and a glass/ceramic melt obtained which can be converted to tiles, bricks, etc.
The process has been proven by melting tonnage quantities and producing specimen floor tiles. unit is under construction in the U.K. Participation in this venture may be available.
A pilot/demonstration
Associated Technology (see Figure 5 - 6 )
I. Incinerator process. Cookson/BMSA have experience in volatilization of non-ferrous metals and believe it would be possible (using special conditions and additives to increase flue dust generation) to reduce the heavy metals reporting in incineration bottom ash.
Experimental work is needed on specific feed streams.
2. Cookson/BMSA technology can also be used directly to vitrify hot ashes emerging from a kiln or incinerator. This takes advantage of the sensible heat left from the combustion of the shredder residues. As with the deTOXTM unit, the small quantity of gases can be ducted into the incinerator system.
5-6
\y Metal
Reductant + Flux
5-7
to tolerate changes in ASR composition, and overall short and long term environmental impact.
Cryogenic Scrap Fragmentation Process
Typically old automobiles are shredded using a hammermill type shredder. In the process of tearing the automobile apart, the shearing action of the mill tends to smash different metals together. For example, copper wiring may get crimped together with a fragment of steel framing or a lead tire balancing weight may remain attached to a steel wheel fragment or be smashed onto another steel piece. Magnetic separation used to collect the steel parts will pick up the aforementioned fragments containing copper and lead thereby contaminating the steel pile. Depending upon the scrap dealer they may selectively remove by hand certain parts of the old automobile minimizing mixing of materials. This can minimize the presence of hazardous metals, such as lead and cadmium, that may eventually end up in the auto fluff. Selective removal of parts today typically includes the battery, copper radiator, catalytic converter, tires, gas tank and possibly the engine block. Other possible sources of heavy metal contamination such as lead balancing weights on wheels and cadmium plated parts could be removed by hand but represent an expensive time-consuming operation.
The use of cryogenics in scrap processing has the potential to produce a cleaner and denser scrap than the conventional process and possibly reduce the volume of fluff produced. The cryogenic scrap fragmentation process was developed by the Belgian scrap processing firm of George et Cie in Liege, Belgium (23). - In the process, scrap automobiles are baled and the bales are conveyed through an insulated tunnel where they are cooled to about -7OC by cold nitrogen vapors coming from liquid nitrogen. Exiting through the tunnel, the bales are partially immersed in the liquid nitrogen bath and the
6-2
Recycling of Auto Shredder Residue
Argonne National Laboratory (ANL) is working on a program sponsored by the U.S. Department of Energy to evaluate various recycling procedures that could be applied to recover value added products from auto shredder residue (ASR) (22) - e on the separation and recycling of the plastics content of ASR. involves the use of organic solvents to extract the various plastics and separate them from each other. Emphasis is on the plastics present in appreciable quantities in the fluff and for which a growing market exists. low density polyethylene, polypropylene, polyvinyl chloride, and acrilonitrile-butadiene-styrene (ABS).
The main thrust of the program at this stage is
A procedure which is under testing at the present time
These are high and
Initial experiments showed that a plastics material showing at least two distinct layers could be extracted from ASR. The separation of these layers appears feasible. More work is planned to quantitate these initial results.
Experiments will also be conducted to identify operating conditions at which ASR can be pyrolized to produce marketable chemicals and/or liquid fuels without having environmentally harmful byproducts. Other chemical processing methods such as hydrogenation may also be tried.
As part of this effort, ANL is also working on identifying markets and market values of products of chemical processing (tertiary recycling) will be compared with products that may be produced via secondary and quaternary recycling procedures. effectiveness, marketability of ,products, ability of process
The criteria for comparison will include cost
6-1
temperature of the bale lowered to about -12OoC, The frozen bales are then processed through a hammermill where they are fragmented into coin size pieces. Reportedly, nitrogen consumption is estimated to be about 0.3 liter per kilogram of steel scrap produced. Various means for separating the glass, dirt, rubber, plastic and metal once the scrap has been fragmented include air classification, magnetic separation and water elutriation or density separation (24 ,25) . --
Various research organizations have evaluated the cryogenic process and conclude that is shows promise in helping solve the auto fluff problem by making fluff more amenable to separation into various fractions such as dirt, glass, plastics and rubber and consequently reducing the volume of auto fluff. justify the cost of cryogenic treatment. this process cannot be justified economically because of the high cost of nitrogen.
By reducing the volume of fluff it may help At the present,
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r
POSSIBLE RESEARCH PROJECTS
A t the p r e s e n t t i m e , on ly t h e s t a t e of C a l i f o r n i a has declared a u t o f l u f f as a hazardous material r e q u i r i n g t r e a t m e n t o f f l u f f p r i o r t o d i s p o s a l i n a l a n d f i l l . A s
d i s c u s s e d ear l ie r i n t h e r e p o r t , chemical f i x a t i o n methods are avai lable f o r t r e a t i n g f l u f f and t h e r e b y p e r m i t t i n g d i s p o s a l i n a l a n d f i l l . However, l a n d f i l l c o s t s are r i s i n g and l a n d f i l l s a r e c l o s i n g . F u r t h e r o b t a i n i n g p e r m i t s f o r new ones i s becoming ex t r eme ly d i f f i c u l t . I n c i n e r a t i o n i n a r o t a r y k i l n o r f l u i d i z e d bed w i l l s i g n i f i c a n t l y r educe t h e
volume and weight o f f l u f f thereby r e d u c i n g t h e amount r e q u i r i n g d i s p o s a l . However, t h e a s h produced by these methods w i l l undoubtedly be declared a hazardous m a t e r i a l by EPA and r e q u i r e t r e a t m e n t . F u r t h e r , because o f the h i g h heat v a l u e o f f l u f f it r e p r e s e n t s a p o t e n t i a l sou rce o f ene rgy t o produce h o t water, steam o r e l ec t r i c i ty . The re fo re , it c o u l d become an impor t an t ene rgy s o u r c e i n t h e
f u t u r e as ou r f o s s i l f u e l reserves d imin i sh . Consequent ly , it a p p e a r s t h a t means o t h e r t h a n chemical f i x a t i o n s h o u l d be
developed f o r d i s p o s i n g o f a u t o f l u f f .
The Voest-Alpine HTV p r o c e s s r e p r e s e n t s a p o t e n t i a l method whereby the ene rgy v a l u e o f f l u f f can be rea l ized and a t t h e
same t i m e t h e ash from combustion of f l u f f i s made i n t o a non- l eachab le s l a g . I t appea r s t h a t t h i s p r o c e s s w i l l r e q u i r e a l a r g e cap i ta l inves tment and t h u s i s p a r t i c u l a r l y s u i t e d f o r a r e g i o n a l o r c e n t r a l o p e r a t i o n whereby f l u f f from s e v e r a l shredders cou ld be p rocessed . However, shredder o p e r a t o r s have e x p r e s s e d the need f o r a p r o c e s s t h a t t hey can i n s t a l l on s i t e t o p r o c e s s f l u f f on a c o n t i n u i n g bas i s and n o t have t o s t o r e o r t r a n s p o r t t h e mater ia l . I t appea r s t h a t a small plasma r e a c t o r cou ld s e r v e t h i s need and it i s recommended t h a t R&D be conducted t o deve lop such a p r o c e s s . The Retech PCR t e s t u n i t
7 - 1
installed at the DOE R&D facility in Butte, Montana, represents a potential means to obtain an evaluation of plasma as a method for disposing of auto fluff. interested in a collaborative project with the shredder operators to evaluate plasma in this application.
EPRI/CMP is
In addition, should EPI build their proposed fluidized bed process for processing auto fluff as discussed earlier in this report, this development should be followed closely as it would burn fluff to produce electricity. Also, Puremets hydrometallurgical process and Cookson's submerged arc furnace process represent potential solutions for treating ash from combustion processes to meet EPA leach test requirements and thus make it suitable for disposal in landfills. The shredder industry should give consideration to supporting projects to demonstrate the viability of these processes.
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BIBLIOGRAPHY
1. Metallic Scrap: The Manufactured Resource, (ISIS) Washington, DC: Institute of Scrap Iron and Steel, Inc.
2. An Industrywide Hazardous Waste Identification Study of the Ferrous Scrap Processing Industry," Clayton Environmental Consultants, Inc., for ISIS, November 1980,
3. Metallic Scrap: The Manufactured Resource, (ISIS) Washington, DC: Institute of Scrap Iron and Steel, Inc.
4. W.S. Hubble, I.G. Most, and M.R. Wolman, of EnerGroup, Inc., and S.L. Natof, U.S. Dept. of Energy, Power Generation from Automobile Shredder Waste Fuel: Characterization and System Feasibility, EnerGroup, Incorporated for U.S. Dept. of Energy, Report No. DE-PR07-871012704, August 1987.
5 - MacRae, Donald and Cowx, Peter. Plasma Furnace Treatment of Electric Arc Furnace Dust as Demonstrated by Bethlehem-Tetronics. Center for Metals Production, Pittsburgh, November 1988, Report No. 88-2.
6. Chemfix Technologies, Inc., P.O. Box 1572, Kenner, LA 70063, U.S. Patent 3,837,872, J.R. Connor, "Method of Making Wastes Non-Polluting and Disposable."
19087; "SealosafeSM Process. 'I
Wichita, KS 67207; "Fujibeton. ''
7. Stablex Corp., 2 Radnor Corporate Center, Radnor, PA
8. New Materials Technology Corp., 8709 Arthur Circle,
9. Lynn, J.D., Technology Group, Bethlehem Steel Corp.,
10. K.E. Boeger, H. Samuels Co., and N.R. Braton, Univ. of Wisconsin-Madison, "Mill Fuel and Mill Cover Recycled from Shredder Fluff."
11. W.S. Hubble, I.G. Most, and M.R. Wolman, of EnerGroup, Inc., and S.L. Natof, U.S. Dept. of Energy, Power Generation from Automobile Shredder Waste Fuel: Characterization and System Feasibility, EnerGroup, Incorporated for U.S. Dept. of Energy, Report No. DE-PR07-871012704, August 1987.
12. Ibid.
13. D.M. Albertson. Development of a Fluidized Bed Combustion System for Auto Shredder Residue, Energy
8-1
Products of Idaho, presented at 1989 Spring National Meeting of the American Institute of Chemical Engineers.
14. Private communication between R.D. Smith, Thermo Energy Corporation and M. Murphy, V.P. Sales for Energy Products of Idaho.
15. Dr. P. Freimann, Voest-Alpine, and DP. G. Starudinger, University of Graz., "Voest-Alpine Hiqh Temperature Gasification Process."
16. Dr. P. Freimann, Voest-Alpine, Thermal Utilization of Shredder Residues by High-Temperature Gasification, Report No. 2228B, January 27, 1989.
17. L.J. Staley. Hazardous Waste Decontamination With Plasma Reactors? U.S. Environmental Protection Agency, Cincinnati, OH 45268.
18. R.C. Eschenbach, R.A. Hill, and J.W. Sears. Process Description and Initial Test Results With the Plasma Centrifugal Reactor, Retech, Inc., presented at Forum on Innovative Hazardous Waste Treatment Technologies: Domestic and International, June 19-22, 1989, Atlanta, GA .
19. Private communication, R.J. Schmitt of CMP and S. Kujawa of MSE/CDIF on December 6, 1989.
20. Plasma-Fired Cupola Development, Volume 2 Description and Analysis of Test Program and Test Unit, EPRI Report EM-5901, September 1988.
21. Private communication, R.J. Schmitt of CMP and N. Pocock of Cookson Group Plc on December 13, 1989.
22. Private communication, R.J. Schmitt of CMP and F. Dudek of Argonne National Laboratory on December 8, 1989.
23. J.H. Bilbrey, Jr. and E.G. Valdez. Use of Cryoqenics in Scrap Processing, Bureau of Mines, U.S. Department of the Interior, Advances in Cryogenic Engineering, 20, pp. 411-416, 1975.
24. C.J. Chindgren, K.C. Dean, and L. Petersonc Recovery of the Non-Ferrous Metals from Auto Shredder Rejects by Air Classification, Burean of Mines TPR 31 (April 1971), 11 pp.
25. L.J. Froisland, K.C. Dean, and C.J. Chindgren, Upgrading Junk Auto Shredder Rejects, Bureau of Mines TPR 53 (March 1972), 11 pp.
8-2
Shredder F l u f f
i
i
L
RILL FUEL AND MILL COVER RECYCLED FR(Y4 SHReDDER FLUFF
K. E. Bceger, H. Samue l s C O . , 1nC.s Hadison, USA. N. R. E r a t o n , U n i v e r s i t y of Wisconsin-Madison, USA.
ABSTRACT
t l idwest Steel Company, a d i v i s i o n of H. Samuels Company, I n c . , located i n Rad i son , Wisconsin, USA is o n e of t h e o n e hundred e i g h t y t w o a u t o s h r e d d e r p r o c e s s o r s i n t h e U n i t e d S ta tes , and o n e cS: t h e t w o hundred f o r t y n i n e a u t o s h r e d d e r processors i n t h e world Cl 3 .
When skredding a u t u m c b i l e s and w h i t e goods an average o f 254 f ig (230 N e t Tons. NT) o+ ferrous end n o n f e r r o u s m e t a l s , and s h r e d d e r r e s i dus a r e g e n e r a t e d p e r s h r e d d e r per e i g h t hour F : - z d a c t i c n shlqt. Tbe annual w a r l d c a p a c i t y of auto shredders excescfs l b . 3 Tg.
A p h y s i c a l bceakdown G? t h E r e c y c l e d materials results i n :
The ;i?rrous acd n o c 4 e r r o u s p r o d u c t s have a ready market. T h e t : ~ e n t y one c e r z e n t s h r e d d e r residue c o n s i s t s c f :
Ecc!-:s, sG9a. sail . SilPSS . C l o c n . iikers, p a p e r . Fii;DSsr, slastic. foam rubber
T h e r e ire nu m x k e t s f37 t h e shredder f l u f f - T h e r e f e r e , the anr;L,aL w c r l d volune, e x c t d i n q 3.780,OOO NT (3,429,194 k i ; j ,
is tYaditiGndIlV dep tzs i t ed i n l a n d f i l l s . These are u s i n g .Iraluable l a n d areas. becoming less popular and h a r d e r t o si te, are p c t e n t i a l c o n t r i b u t o r s t o e n v i r o n m e n t a l p o l l u t i o n , and reprssent i n e i f i c i e n t us’es o f p o t e n t i a l r e c y c l a b l e resourcas.
-
1 A- 1
c o v e r s u b s t i t u t e . I t h a s many a d v a n t a g e s t h a t make i t supe r io r to t h e soil cover u s e d today .
INTRODUCTION
Shredder f l u f f is t h e $ i n a l p r o d u c t i n t h e a u t o s h r e d d i n g p r o c e s s , S c r a p automobiles, w h i t e goods , and loose s h e e t i r o n are sh redded . The steel pfoduct is m a g n e t i c a l l y s e p a r a t e d i n t h e f i r s t s t age of t h e s e p a r a t i o n p r o c e s s . The n o n b e r r o u s metal p r o d u c t is t h e n s e p a r a t e d m e c h a n i c a l l y f r o m t h e n o n - m e t a l l i c materials t h a t are l e f t i n t h e p r o c e s s i nq stream e
S h r e d d e r + I u f + c o n s i s t s 09 a v a r i e t y o+ n o n - m e t a l l i c materials. T h e major components are:
. Rocks, s a n d , s o i l , Glass , ceramics . C l o t h , f i b e r s . paper . Rubber , p l a s t i c , foam r u b b e r . Tramp f e r r o u s ( f e ) and n o n f e r r o u s ( n l f e ) metals t h a t escaped pr imary s e p a r a t i o n
X R 1984 there w e r e 182 a u t o s h r e d d e r s i n t h e USA, They h a d . a total p r o c e s s i n g c a p a c i t y of 13,268,000 NT (12,036,650 M g ) o f scrap a u t o m o b i l e s , w h i t e goods, and loose sheet iron. T h e t o t a l p r o d u c t i o n capaci ty o f s h r e d d e d steel scFap exceeded 9,951,000 NT (9,027,488 Hg).
Gutside of the Uni ted States t h e r e w e r e 20 auto shredders ;n Canada w i t h a p r o c e s s i n g c a p a c i t y o f 1,094,000 NT (993,399 us) and shrocdnd S ~ E I O ! scrao p r o d u c t i o n o f 813.000 NT (737,549 M q ) . An a c d i t i o n a l 49 auto s h r e d d e r s were i n operatzan across t h e f o u r c o n t i n e n t s , w i t h most of these located i n Western Europe and t h e United Kingdom.
Using the proce6sing capaci ty of t h e Un i t ed States and Canada and a p p l y i n g t h e a v e r a g e p e r c e n t a g e of mater ia l s nat recovered i n t h e f e r r o u s and n o n - f e r r o u s s e p a r a t i n g s y s t e m s (21%), t h e e s t i m a t e d ' g e n e r a t i o n o f s h r e d d e r f l u f f would e x c e e d 3,013.000 NT (2,734,200 Plg)
THE SHREDDER FLUFF PROBLW
S i n c e t h e b e g i n n i n g of a u t o s h r e d d e r s , t h e method of d i s - p o s a l o f s h r e d d e r f l u f f has remained b a s i c a l l y unchanged. I n t h e United S ta tes open dumping a n d / o r b u r n i n q are n o l o n g e r common, but l a n d f i l l and /o r i n c i n e r a t i o n w i t h o u t capture of e n e r g y are E2J. " In Europe a t p r e s e n t there is no p r a c t i c a l use +or the n o n - m e t a l l i c f r a c t i o n s re- m a i n i n g w h e n metals have been removed, and t h e s e ar.e s e n t
A-2
t o l a n d f i l l " C33.
Th8 s h r e d d e r f l u f f p r o b l m is t a U f t f - f r C R t . d , such as:
LAC& of l a n d f i l l , - U i t h t h e r i s i n g m v i r o n m e n t a l c o n c e r n s i n t h e Un i t ed States t h e r m have been ever i n c r e a s i n g e n v i r o n m e n t a l r e g u l a t i o n s c o n c e r n i n g t h e s i t i n g of new l a n d f i l l s . Needless t o s a y t h i s h a s r e d u c e d t h e number of p o t e n t i a l l y a v a i l a b l e s i tes, as w e l l a s t h e premature c l o s i n g of some e x i s t i n g s i tes t h a t c a n ' t comply w i t h t h e c u r r e n t s t r i n g e n t r e g u l a t i o n s .
R i s i n g l a n d f i l l fees - T h e t i p p i n g fees a t l a n d f i l l s h a v e r i s e n d r a m a t i c a l l y due t o increased o p e r a t i n g cos t s . T h e r e a lso is t h e r e c e n t imp lemen ta t ion 09 a d d i t i o n a l t i p p i n g fees t o h e l p fund r e c y c l i n g e f f o r t s by s t a t e and local gove rnmen t s , a s w e l l as p r o v i d e a d i s i n c e n t i v e t o h e l p r e d u c e the amount of material d i s p o s e d of a t l a n d + i l l s .
I n c r e a s e d t r u c k i n g cos ts - T h e s e have occured b e c a u s e o f t h e d i f f i c u l t y i n l a n d f i l l s i t i n g . L a n d f i l l s are fewer and t e n d t o be f u r t h e r away.
No o the r e c o n o m i c a l l y v i a b l e s o l u t i o n s - O t h e r t h a n the t e m p o r a r y d e l a y i n g o f d i s p o s a l cos t s by s t o r i n g t h e s h r e d d e r f l u f f w h i l e l o o k i n g f o r o t h e r a l t e r n a t i v e s , l a n d f i l l i n g h a s been t h e o n l y practzcal method of d i s p o s a l .
Remaining e c o n o m i c a l l y v i a b l e - In t h e face of s h r i n k z n q a p e r a t i n g m a r g i n s , due to t h e d e p r e s s e d sc rap f e r r o u s and n o n - f e r r o u s metal m a r k e t . d i s p o s a l c o s t s p l a y a n e v e r i n c r e a s i n g r o l e i n d e t e r m i n i n g the p r o f i t o r l G s s o i a ShreGd 1 ng oper a t i on.
ORIGINATION OF PRODUCT CONCEPT
T r a d z t i o n a l l y s h r e d d e r f l u f f h a s been c h a r a c t e r i z e d a s a by-product or s o l i d w a s t e material, t h a t had n o v a l u e and w a s to b e d i s p o s e d o f as c h e a p l y a s p o s s i b l e .
The h i s t o r y of t h e s c r a p i n d u s t r y is t h e reuse of t h e d i s c a r d s of s o c i e t y , and the. c o n v e r s i o n of t h e s e d i s c a r d s into u s e f u l resources. The key c o n c e p t t o s o l v i n g t h e s h r e d d e r f l u f f p roblem is t o a p p l y t h i s l i n e of t h o u g h t t o t h e d i s c a r d s of t h e a u t o shredder i n d u s t r y . S h r e d d e r f l u f f w a s s i m p l y a product w a i t i n g t o b e d ' i scovered and developed .
S h r e d d e r f l u f 9 must b e t h o u g h t of n o t as a w a s t e p r o d u c t , but a new p r o d u c t t h a t needs development . The i d e a l e a d i n g t o t h e deve lopment of flILL FUEL resulted f r o m a series of d i s c u s s i o n s between H i d w e s t Steel Company p e r s o n n e l and p r o f e s s o r s f rom t h e f l e c h m i c o l E n g i n e e r i n g Depar tment at t h e U n i v e r s i t y of Wisconsin. The r e s u l t s of t h e s h r r d a e r f l u f f
3 A- 3
c h a r a c t e r i z a t i o n s t u d y C41 i n d i c a t e d t h a t t h e eomponen t s of ,
+ l u f + l a r g e r than 2" (S cm) appea red t o b e p r i m a r i l y c o m b u s t i b l e materials e
The deve lopmen t of HILL COVER was t h e f e s u l t of t w o d i s c u s s i o n % . T h e f i rs t r e s u l t e d f rom t h a a f o r e m e n t i o n e d m e e t i n g a t the U n i v e r s i t y of Wisconsin. f t w a s s u g g e s t e d t h a t the s h r e d d e r f l u f f components t h a t were less t h a n 2''
The s e c o n d d i s c u s s i o n was w i t h t h e R e c y c l i n g C o o r d i n a t o r for Wiscons in Department of Natura l Resources . He p a i n t e d out t h a t other i n d u s t r i e s , w i th potent ia l l a n d f i l l materials,
caver supp lemen t a t l a n d f i l l s .
( 5 cm) may have a p p l i c a t i o n as soil c o n d i t i o n e r s or a d d i t i v e s . -
were g i v e n a p p r o v a l f o r t h e i r material t o be u s e d as d a i l y __
PHYSICAL CH6RACTERISTICS OF FLUFF
The a n a l y s i s of t h e s h r e d d e r f l u f f g e n e r a t e d by M i d w e s t S t e e l Company was done by t h e U n i v e r s i t y of W i s c o n s i n . The companen t s of shredder f l u f f w e r e d e f i n e d by type and by size.
T h e p r i m a r y types 09 material components t h a t make up s h r e d d e r + l u f f ( f i g . 1) are:
Ferrous metals - 2.2% N/Ferrous m e t a l s - 6.1% I n s u l a t e d w i r e - 1 , l . X Non-metal1 i c s - 98.6:'.
F i g u r e i
4 A-4
Shrrdder f l u f f was broken down i n t o t w o primary s i t e categoriis.
Larger t h a n 2" (5 em) - 21% (F ig .2) Smaller than 2" (5 en) - 79% ( F i g .3)
The breakdown by p e r c e n t a g e s of i n d i v i d u a l components i n each size category of shredder f l u 9 9 was:
A. Larger than 2" (5 cm) ( F i g . 21)
Ferrous metals - 4.4% N/Ferous metals - 16.5% I n s u l a t e d w i r e - 4.3X Non-metall acs - 74.8%
-5%)
B. Smaller than 2" ( 5 c m ) (Fig. 3)
-Ferrous metals - 1 . 5 % ' "/Ferrous m e t a l s - 3.4%
I n s u l a t e d wire - 0 . 3 X Non-met811 i c s - 94.8%
S A-5
F i g u r e 3
I n d e t e r m i n i n g t h e t y p e s of material c o n c e n t r a t i o n s i n t h e shredder f l u f f by size, t h e f l u f f w a s s e p a r a t e d i n t o four c a t e g o r i e s : (Fig. 4 )
M a t e r i a l l a r g e r t h a n 3'' (12.5 cm) flaterial 2 - 5" ( 5 - 12.5 cm) Material 1 - 2" ( 2 . 5 - S e m ) tlater:al smaller t h a n I " (2 .5 c m )
The graphs i n Figs. 4 and 5 show t h e d i s t r i b u t i o n i n t h e +our sites. T h e c o n c e n t r a t i o n of n o n - m e t a l l i c s (74.7%) is p r e d o m i n a n t l y i n t h e less t h a n 1 i n c h (2.5 c m ) size. Y h e c o n c e n t r a t i o n of metal l ic5 t b 8 X I is p r e d o m i n a n t l y i n t h e material t h a t is larger t h a n 1 i n e h (2.5 c m ) .
The g e n e r a t i o n of t h e MILL FUEL and HILL CUVER p r o d u c t s can be accompl i shed w i t h t h e u s e of a rotary s c r e e n t r o m m e l (Fig. 6 ) . The t r o m m e l is made up w i t h the i n i t i a l s e p a r a t i o n s e c t i o n h a v i n g a s c r e e n n i t h . 1 i n c h (2.9 c m ) h o l e s t o remove t h e f i n e f r a c t i o n f r o m t h e s h r e d d e r f l u f f . T h i s material
The s h r e d d e r fPufi t h e n p a s s e s i n t o t h e s e c o n d a r y s e p a r a t i o n area of t h e t r o m m e l w h i c h is e q u i p p e d w i t h a s c r e e n h a v i n g 2 i n c h ( 5 e m ) holes. Y The t w o f r a c t i o n s c o n t a i n t h e m a j o r i t y of t h e r e c o v e r a b l e f e r r o u s and n o n f e r r o u s metals. The metals - can now be m a g n e t i c a l l y and hand s e p a r a t e d . The n o n m e t a l l i c material i n thejlarger than 2 i n c h ( 5 c m ) f l o w becomes MILL FUEL. The material from t h e larger t h a n 1 i n c h (2.5 c m ) and less t h a n 2 i n c h (S c m ) is added t o t h e HILL COVER,
p r o c e d e s by conveyor d i r e c t l y t o t h e HILL COVER s t o r a g e area. -
__e
I SIZE IN INCHES
HILt FUEL
__ The c r e a t i o n o f flflrL FUEL from s h r e d d e r f l u f f allows t h e c a p t u r e and release 09 t h e h e a t i n g v a l u e c o n t a i n e d i n f l u f f . I t s ca lor i f i c v a l u e e q u a l s or e x c e e d s other a l t e r n a t e fuels such as wood and re fuse -deraved f u e l (RDF). (Fig. 7)
Proximate Analysis of HILL FUEL
A: S i z e >3/4" (1.875 c m ) - d r y b a s i s V a l a t i 1 es 56.9% fish 37.4% F i x e d carbon 5.7% C a l o r i f i c v a l u e 7 ,157 FTU/lb
16.6 flJ/kg
B: S i z e >2" ( 5 em) - d r y b a s i s V o l ati 1 es 65.3% Ash 22. br. F i x e d carbon 12; 1% C a l o r i f i c v a l u e 10,770 ETU/lb
25.0 R J / k g
I
0 A- 8
fish Fu,sion Temperatures Qf HILL FUEL
I n i t i a l Deformation 2245. F (1229. C) f l u i d Tempcrr8twa 2595. F (1423. C)
C h l o r i n e c o n t e n t of MfLL FUR - 0.569% C63
A s a r e s u l t of t h e p r o x i m a t e a n a l y s i s it was d e t e r m i n e d t h a t t h e i d e a l r i t e of MILL FUEL shou ld b e t h e f r a c t i o n of s h r e d d e r f l u f f which is 2 i n c h e s (9 em) and l a r g e r . This s i z e al lowed for t h e reduced ash c o n t e n t and a more desireable c a l o r i f i c va lue .
T h e r e are many p o t e n t i a l m a r k e t s f o r HILL FUEL. t h a t c u r r e n t l y b u r n sawdust and wood c h i p s as s u p p l e m e n t a l fuel would be p r i m e c a n d i d a t e s . T y p i c a l l y t h e i r f u e l d e l i v e r y s y s t e m s and boi lers are s u i t a b l e f o r u s i n g MILL FUEL w i t h o u t any r e t r o f i t t i n g . I n d u s t r i a l b o i l e r s t h a t c u r r e n t l y use h i g h ash c o a l , or RDF C71 may a l so b e able t o make use of MILL FUEL w i t h m i n o r m o d i f i c a t i o n s . The s h r e d d e r operator may also c o n s i d e r u s i n g MILL FUEL and a d d i t i o n a l a l t e r n a t i v e f u e l s f o r co-genera t ion w h i c h could h e l p r e d u c e t h e o p e r a t i n g cost of a sh redd ing o p e r a t i o n .
Paper mills
ZXLL tC'.'E.=! W P S l e v e i G D e d as a product i=r use a s a repiacemefit + o r . or as a supplement t c 9 daily so i l cover at lace+iiLs.
't c = n s i s t zt+ t b e -cn-metal l ic f r a c t i o n o+ s h r e d d e r f l u + + ,,,at, 1 5 u n d e r 2 :r.ct-,es ( 5 cn) i n size. T h e comocs;t:cn :s
I -+ s. ~ ~ n a . c;rt. ;l;ss particles, plastrc. and var:aus + i k e r s .
i L
The a d v a n t a g e s of u s i n g HILL COVES v e r s u s s o i l a s a d a i l y cover are:
. COVERING ABILITY - Blowing d e b r i s is controlled by ; I r e v e n t i n g access by t h e wind t o t h e w a s t e .
. VECTORS - By a c t i n g as a b a r r i e r between t h e w a s t e and the a n i m a l s , insects. and b i r d s i t p r e v e n t s their r e a d y access t o t h e w a s t e as a source of food and a r e a d y b r e e d i n g env I ronmen t
. ODORS - Minimizes odors by p r o v i d i n g a barrier to t h e i r movement out of t h e waste and by a b s o r b i n g o d o r s as t h e y p a s s t h r o u g h MILL COVER.
. SAFETY -'By s e a l i n g o f f , t h e w a s t e safety hazards p r e s e n t e d by sha rp objects and disease are minimized . T h i s f u n c t i o n is a c c o m p l i s h e d by p r o v i d i n g a barr ier be tween t h e
9 A- 9
waste and anyono walking or driving on it.
. ACCESS - The unstable nature 09 solid waste presents very dangerous surface on which to drive. The f i b e r
contmnt of HILL COVER 'provider a stable and firm bare on which vehicles can deliver waste to the active disposal face. . WASTE EROSION - By sealing off the waste from rainfall, a m d runoff erosion is minimized.
dusty or very muddy with vehieles frequently getting stuck.
drier surface.
. ACCESS ROADS - These roads are normally either vary Access roads of M I L L COVER provide a sa9er, mcre stable and -
. OPERATOR EFFICIENCY - The equipment operator spreading the daily cove- won't be exposed to blowing dust from the cover material on dry windy days as the matting characteristic of IYXLL COVER traps dust. On wet days the operator won't be spending time freeing stuck equipment.
. DEPTH O F C3VER - The depth of daily cover may be reduced due to the matting charaeteristics of HILL COVER. This could result in a significant increase in t h e life of the landfill.
. EQUIPRENT EFFECXENCY - Equipment will b e exposed to less dust an the daily operation thus extending the life o i f:lteFs, air lines. b r a k e systems and reducing daily mal ntenance.
e CONSERVES VALUABLE SOIL RESOUiiCES - The soil t h a t is -eqoved f o r excavatron can be used fcr othsr p c r p o s s s . Tap SO;! can '?e reused; marginal soil can be :;sed as f i l l at esnstrLction s i t e s .
FI p r i m a r y concern about using MILL C W E 4 was the concen- t P a r r o n s o f heavy metalr. This concern has been addressed C53. The repsrt concluded that the shredder fluff evaluated w a s found to be below iederal regulatory definition o f a hazardous waste. These results plus additional documentation from studies and tests made at the University o f Wisconsin, were presented to the Wisconsin Department of Natural Resources. The national and local findings w e r e acceptable and the tlXLL COVER proqram is in the test stages at a local landfill.
T h e potential o+ using f lILL COVER as a daily soil cover -
substitute will save the disposal fees at landfills as well as f i l l a need for the landfill operator.
10 A-10
SHREDDER METALS
The ferrous end non-ferrous metals that are recovered from the shredder fluff during the separation process are returned to the original ferrous and non+errous product streams.
REFERENCES
(1) P. Bralower, ''Exclusive 1984 Survey of Automobile Shredding", SCRAP AGE, October 1984
(2) J. Kinstle, Recycling of Organic Polymeric Materials, The Impact o f Haterra1 Substitution on the Recyc1abil:ty o f Automobiles, The American Society of Mechanical Engineers, 1984, p . 167.
( 3 ) E. Henstock. The European P i c t u r e , The Impact of Mater:al Su5st;tution G ~ I t h e Recyclability of Automobiles. The Gmerican Society a+ flechanrcal Engineers, 1984, p. 184.
( 4 ) D. Aer-ts. characterization Study of Shredder F l u f f , t h e University o f Wisconsin, Engineering Research, Dec. 1984
( 5 ) Clayton Environmental Consultants, Inc. , A n Industry- w i d e Hazardous Waste Identification of the Ferrous Scrap Processing Industry, Prepared for The Institute of Scrap Iron and Steel, f n c . November 10, 1980
( 6 ) D. Aerts, Trace Element Analysis o+ Hill Fuel, The University of Wisconsin, Engineering Research, May 22, 1985.
(7) Conference on test results of MILL FUEL, Boeqer and others. College of . Engineering, University of Wisconsin, June 14, 1985
11 A-11
APPENDIX B
Characterization and System Feasibility
AND SYSTEM FEASIBILITY
I V k ! G. MOST EnerGroup. Inc., Panland, Maine
AB" &sing costs and scarcity of sites are driving fenous
scrap shreddtr operators to seek altemitiva to landdl1 waste disposal. A resource recovery concept is pre- sented. whereby the IiGIt fraction of shredder raidue (fluff) is used Y a fuel to generate electric power and steam for on-site use or commodity d e .
A database generated from the shredding industry inc!uda faality processing capacities, waste generation races and disposal costs, energy usage and costs. The waste was charactenzed by physical and chcmid anal- ysis, and test bum in a rotary Un kcinerator.
Several conceptual energy recover). and conversion systems are structured. Capiul and operating costs are calculated for plants with varying s u e and configu- rations. The projected economic returns vary with scale. local disposal costs, electric power r a t e and availability of a steam customer.
IhXRODUmOX
The steel shredding industry procases discarded can. appliance and other predomimdy steel Objkts to produce fragmented stet1 for r d e 8s 8 f d t o c k for steel making. Shredding provides imponvlt a- nomic and environmental benefits u ur dlcmrtlve tO
!TIVART L NATOF U.S. Depanment of Energy
Office of Industrial Programs, Conservation Washington, D.C.
other scrap processing methods. Nonetheless, shred- ding produce a waste stream for which no alternative to landfill disposal is pracuccd. rtus waste stream, termed "fluff," consists main!?
of the nonmetallic portion of automobiles. E.xc!udir,g t t r c ~ . batterin, and radiators whch are customarily removed pnor to shredding, Buff IS generated from intenor PIatKtC trim. upholstery fabnc and filkr. in-
sulauon, and padding. From a distance. Auff appurs to k a homogeneous mass of brown, oily fiin. Upon closer exanxination, it is Ken to include pieta of alu- " a m , mbber, paper, hard plasuc, wnyl. glass. and placed metals from the m p , as well as rocks and dm, depending on scrap handling practices.
Flubhas bem shown [ 11 to be a nonhazardous was;e. Many I'uldblIs arc no Ionga accepung fluf. The pos- sibility of de facto prohibitions on landfilling and nsing disposal costs everywhere are dri;ing shredder oper- ators to seck altemauves. Rris paper repom on M investqatron funded by the
Unitai S u t a Deparrmcnt of Energy, Office sf Indus- vial Programs, Conuacr No. DE-AC07-84ID 1255 1, to develop a wble p m to utilize the cncgy content of fluff. It is estimated that thls matenal w111 repraent a gross potential fuei value of 0.06 quads (0.07 x 10" J) from U.S. sources tn 1995. In evaluating the feasibility of using fluff as an energy
source. the following areas u e addressed:
-
-
(61 fluff as 3 waste fuel: physical 3nd chemical prop-
(cJ Euff-to-energy systems: test bum, conceptual in-
ldl economic feasibility analysis
erties: com5us:ion technology
SHREDDISC ISDCSTRY
T h e Metal Scrap Research and Education Foun- dation (the research foundation of the Institute of Scrap Iron and Steel. a scrap processing trade orga- nization) IS an official paninpant in the project. .As a f a u l t of their efforts, the authors oburned information on 50 shredding facilitia. out of nearly 200 cunexltly operating in the United States.
Until the late 1950's. there was no Ruff. While a market d o e exst for uncleaned automotive scrap, processors are paid a premium for scrap with non- metals and undesired metals removed. Historically, this was accomplished by open burning whole auto hulks or hand dismantling. With the advent of pro- hibitions on open buming of solid waster, some pro- cessors developed incinerators wrth the capacity to bum the combustibles out of one or more automobiles. and direct smoke through an ahburner to complete combustion. Energy costs of the method were prohib- itively high and air pollution control inadequate. The shredding procas was adopted for obsolete scrap in order to remove nonmetallia automatically, without requiring combustion.
Shredding systems are used to process waste auto- mobiles. white goods and miscellaneous "light iron" (waste objects containing sheet and light structural s : d ) into: (a) fragmented steel; fb) nonferrous metals and other high density material; and (c) low density matenal or "duff'. The general; process is dcscnbed below [2].
Equi pmtnt
A cran: or conveyor fceds individual waste objects to a gratedischarge himmemill-type shredder. Shaft honepower is provided by electric motor or intemal combustion engine. Shredder power requirement range from loo0 hp (750 kW) to 6oco hp (4470 kW9 depending on processing capacity.
Following discharge from the mill, fist-sized pieces of shredded waste are conveyed througb I clcaning and soning system. Ferrous metals are collected by magnetic separation. Ruff is collected by cyclone air
classifiers or fluid washing. The number and sequence of separation processes varies, depending on what the panicular operator wants to recover.
Energy Use
In addition to shredder shaft power requirments. shredder systems w numerous electnc motors for ma- tenal handling and air moving. A singfe pneumatic Buff cfcaning statlon m3y require in exccss of 2 0 0 h p (IS0 k W for blower and cyclone suction fam C m - bined auxliiary power requirements may be as high as loo0 hp (750 kW9.
Most shredder systems are ail-eiectnc, purchasing power from the local utility. Due to the intermlttez: surges in shredder load coinciding with feeding car hulks. etc., to the mll. these operations incur s i p f i - a n t demand charges. -=larger operators aiready spend more than half a million dollars per y u r on electric power.
The few operaton which drive shredders with dlese! or natural gas 6rcd h e m a l combustion engines are relativefy insulated from electricity cost increases. They are not, however, immune to potential dramatic increaxs in fuel prices.
Each facility is different. Variafions in raw matend content (autos vs other), shredder grate spacing, and number, type, and arrangement of cleaning procsses result in varied relative weight percentages (steel b s
BUir vs nonfemus) and by-product compositions. "Nonferrous" defined as the high density fiacrorl
not sqarated magnetically, contains between 20% and 80% by weight recoverable nonferrous metal. The re- mainder is a mixture of giass, xubbcr. dense plastics.
"Ruff," defined as the low density fraction not sep anted magnetidy, contains plastic and textile fabncs. foam and fiber insulation and padding. Tksc com- bustible matenals occupy most of fluffs bulk volume, but average only 47% by weight. They are mixed with fragments and ha of ferrous metal, and "nonferrous" (see above). There noncombustibles are the principal source of the ash generated by buming fluff.
Of the three major shredder f e d stocks. autos have the highest weight percentage of nonmetallic content. followed by white goods. and light iron. Therefore. fluff generated per ton of shredder feed varies according to the mix of feed material procesxd. Shredden proc- asin8 in excess of 90% by weight autos yieid approx-
fins. ferrous metal. and "tlufi' (see &!ow).
92 I
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imately 78% ferrous meul. 2% nonferrous and heavy nonmetallic, and 20% fluff by weight.
'
Ruff Dirposoi
h'onferous shredder discharge is commercially re- cycled using a vanety of gravity separation methods. Tne disposal problems (if any) and fuel propenies of wastes from this activity are not within the scope of this paper.
Flud IS not recycled. The Department of Energy has funded rcsurch by the Plastics Insatute of b e n c a . Inc. to process fluff and obtain a "wde spec" plastic molding feedstock. The commercial viability of this process has not been demonstratkd [3]. Ma: operators landdll fld. Some have sufficient
propeny at their shredder or a nearby site. Others rely on public or private landfill operations.
Fluff contains lead, attributed to car batteries, ea- haust systems, body repair solder, the highway envi- ronment and other sources [4]. A comprehensive study using U.S. Environmental Protection Agency (€PA) protocol [ 11 concluded. however, that representative sampling shows l a d is not present in Buff at a haz- ardous level.
Nonetheless. some landfills have stopped accepting fluff, forcing shredder operators to stockpde it or haul it to more distant landfills. This type of de facto pro- hibition may become more widespread. Evenwhere, disposal is getting more expensive. Dozens of industry representatives interviewed by the authors agree chat many of their number will be forced out of the shred- ding business unless they find an altern3tive to land- filling.
Dispod Alterrudrcr
It may become feasible to reduce the disposal volume ' and/or weight by separation and recycling, on the
model of "nonferrous" recycling technology. Several air or fluid classification and screening de-
vices may be adaptable to separating Ruff into its fabric, metal, molded plastic. fiber. and fine fractions. Mag- netic separation devices may k adaptable to legre-
gating fine into highly ferrous and nonferrous fractions.
T h e types of material separation have not been applied to shredder fluff. Until recently. disposal costs were low enough that investment in separation proc- ass was unwarranted.
Fluff volume can be reduced through baling or in- cineration. Some Iandfill operations can offer reduced
Ras bem baled to allow simplified. lower cost handling, and incrwsed struczurd htegi ty in the landfill. Whether the cost of baling is odset by reduced disposal costs must be evaluated on a case by case basis.
-
.
. I
PX . 'r
FLUFF As FUEL Fluff samples were analyzed to assess the technical
feasibility of using fluff as fuel and to determine ap- propriate combustion equipment.
Seventy-two 55 gal d r u m of fluff (six each from i l sites) were collected to provide sufficient fuel for a j day test burn. Representatwe analysis samples were removed from each site's sixdrum contnbution through the caning and quartering technique. This solid waste sampling technique begins by shaping the bulk quantity into a symmetrical cone. Tne cone IS divided into four quaners using perpendicuiar diam- eter l i n a Opposite quaxtcrs are discarded and the procedure repeated w t h the retained quanen. The entire procas is repe3tc.d until the weight or volume of the retained quarters equals the desired sample size PI.
- Chcmicml Properties
-
23
34
2
10
2 5 4 5 3 : 5 4 4 : : 5 7 2 53 4 8 4 7 3 5 4 3
6 6 4 1
43 2 4 6 0 2 5 4: 4 3 4 9 5 4 2 5
55
0 6 3 8 3
0 .5 5 . 2 0 . 5 1 . 4 0 . 3 3 - 9 0 . 4 1 . 9 0.1 v . t
0 . 5 L 6 . 3 0.2 r.L
* . .
. . I
7 2 66 1: 3.5 1 6 . 9 9 . 2 6 0 ( 2 : 5001 1 2 , 8 3 0 ( 2 9 800)
25 2 4 0 s . 2 0 . 7 2 . 9 0 0 ( 6 8 0 0 ) 0.920 ( 2 3 1C0;
4 4 4 4 3 0 . 4 3 . 4 5 , 4 2 0 ( 1 2 603 : 11.623 ( 2 7 9 % '
4 3 4 3 3 0 . 4 3 . 8 5 . 4 9 0 (12 8 0 0 ) 11.900 (27 B O G )
Fluff has a mean HHV of 5400 Btu/Ib (12,560 W / kg). Assuming that 200 shredders generate an average of 1,OOO tons (13,600 t) per year, fluff currently rep- resents a gross potential fuel value of 0.033 quads (0.035 x 10'' J). Due to increasing plastics content of cars [6], this total is expected to double in the next decade.
The ash and moisture contents of as-received sun- p l a vary widely. Consequentially, as-received HHV varies over a wide range: 2900 to 9260 Btu/lb (6750- 21.530 U/kg). Moisture-and asb-free (MAF) HHV, however averages 11,600 Btu/lb (26,980 W/kg), and varies over a narrow range: 9930 to 12830 Btu/lb (23,100 to 29,840 W/kg). ApparentIy. the combustible fraction of .luff is similar for samples which M e r widely in noncombustible content.'
D e relationship ktwccn dry basis ash content and fuel value of fluff sample is shown in Fig. 1; Depending on the shredding proccss, 0uf contarru a variable weight percentage of noncombustibia (ash). While the fuel value per pound of flufdecrcasa with increasing noncombustible content. the duffincreajes as a waght percentage of scrap processed. The overall available Bud energy from shredding automotive scrap is rela- tively constant, approximately 2.2 x 10' Btu/ton of scrap (2.5 x 10' W / t of &rap).
Physicrl Properties
94
During this study, fluff samples were handled and inspected extensively. Several shredding faciIitia were visited, and numerous operators were interviewed. Tke authors learned that while fld is predominantly non- m e d i c , it CenrainS si&cant amounts of a wide va- riety of metals, plated metak, metal-plated-plastin. and some ~CKOUS meed. Combustibles indude plastics. textiles, wood and paper.
The bulk density of fluff is approximatel? I Ibifr' (320 kg/m').
Some ha were readily removed from duff thtou& in. .( 12 mm) and X in. (6 mm) screens. The weigh!
percentages of separated fractions are shown in Tab!: 2 for 11 sample. n e minus in. (- 6 am) fraczicn averages 35% by wd&t and ranga from 19% to 5 5 5 . The minus plus :! in. (- 12 + 6 mm) fractio:: 2 i -
eragcs 20% by weigllt and range from 16% to 3%. The plus in. (+ 12 mm) fraction averages 46% by weight and ranga from 27% to 64%. The authors arc currently studying separaricn of
noncombustible from shredder Buff. Compositicn cf f i n e fractions will k determined. Separating qui;>. m a t and methods. and cffecu oil combustion, air m:s- sions and ash p r o p d a will k examined [7].
B-4
6 .
\ A \
P
-4
FIG. 1 SHREDDER FLUFF: ENERGY VALUE VS ASH CONTENT (Dq Basis)
In an unrelated study [8], researchers removed an unspecified undersize fraction of din, stone and glass fina from a fluff sample. The remaining oversize ma- terial was analyzed piece-by-piece for physical com- position.
'
-'
FLLTF-TGEYERGY SYS"E3f CONCUPT Rotary kiln combustion technology was chosen to
to-energy system was conceptualized for engineering and economic analysis.
test the w a ~ t e fuel p e r f a m e of fld. A tOtd fluff-
T a Burn - A three dry test burn was conducted at Industmnics, Inc., South Windsor. Connecticut. Approximately 3.5 tons (3.16 t ) of fluff were pracmed in a 2 million Btu (2.1 GJ) per hour Industronia rotuy kiln equipped with secondary combustor. waste h a t boiler, bag-
TABLE 2 FLUFF SEPARATION: SCREENED PARTICLE SUE FRACTIONS
I *
I *
2*
house, and packed tower scrubber. This equipment was chosen due to the simplicity and flexibility of the rotary kiln design, and its proven material handling upability.
The rotation of the refactory-tined kiln priaury combustor advances fueI down a slight incline to the ash discharge end. A bucka ash conveyor collects ash from a hopper blow the kitn end and deposits it in a covered disposal container. Water sprays are used as nccasaiy to quench any glowing embers of noncom- busted rmrterial which may occur in the ash due to fuel overloads.
Equal volume of ru-received fluff from each of dever! sits sampled constituted the composite fuel mixture. Calculated fucl analysis is &own in Table 1. This m i x t w was fed at rata varying from 200 to greater than 400 Ib (91-181 kg) per hour. Feed rate was accurately controItd by a t a p e d auger "shrcd- der-feeder'' of proprietary deign.
Auxiliary fuel (natural gas) was used to bring the combustion equipment from ambient temperature to about l5OOT (SZCrc), when f luf fed was begun. Flu3 ignited readily, and as won as sufficient flutr was burn- ing to maintain temperatures, ~ n v a i - f e d was discontinued for the Wane of a c h &y. R d self- sustained combustion temperature between 17WF (93VC) and 2OOOT (1OWC) by Varyins fad rate and draft control.
Ruff was reduced 55% by weight and 80% by vel- umc. The resulting ash b gray, w d y and free flowing. with some chunks of slag and m c d . Average moisture
95 I
B-5
TABLE 3 FLUFF COMPONENTS [Din, Stone and Class Fines Removed (511
wrr:nq : I
5 3
> \*; . .: .
content is 1%. Lolatile matter 695, with no fixed car- bon. Metals include 25% iron by weight.
sulted in lead concentrations ranging from _=--_ 28.0 to 31.6 m g ~ ~ % % ~ A i f i i s l a d may result from previous wastes combusted in the Industronics unit, or from shredder Buff itself. Waste which exceed 5.0 mg/L oflead may be classified as hazardous by w u e of EP Toxicity.
Stcam pressure between 50 and 75 p i g (340 and 520 Wa) was muntained in the w s t e h u t boiler. Steam flows were not recorded.
Air emissions data from the second and third days of