Sinter

Sintering technologies

40% of the worlds sintering

Iron ore sintering has stood at the heart of the ferrous metallurgical processes for over half a century. Outotec has solid experience in agglomeration of ne-grained iron ores. We have built over 400 sintering plants with capacities ranging from 600 to 20,000 tons per day since1920. Today, 40% of the worlds sinter is produced by our technology. Besides iron ores, it can also be applied for sintering of manganese ore nes.

Over the years, we have developed a number of inno-vative technologies that increase the performance and reduce the capital and operating costs. Long-term research and testing with raw materials of different origins and process parameters, coupled with conti-nuous development and improvements in mechanicaldesign and process automation have made us an unparalleled technology partner.

002 More out of ore!

Outotec sintering processOutotec sintering process begins with the preparation of raw mix from iron ores, uxes, in-plant dust and spillage nes, solid fuel and return nes. These materials are mixed and granulated in one or more stages. Water is added in order to assist the raw mix in obtaining optimum permeability for lower electricity consumption, maintained by conveying the raw mix carefully onto the sinter machine. Its surface is then ignited, air being induced through the ignited layer and sintering proceeding in the vertical direction in the sinter strands material bed. Subsequently, the sinter is cooled, usually in a separate sinter cooler, located at the sinter machines discharge outlet. The cooled sinter is crushed to a pre-deter-mined maximum particle size. Undersized sinter that is not suitable for the blast furnace is recycled to the return nes bin. A certain quantity, usually 1020 mm, is screened out and recirculated to the sinter machine, where it serves as a hearth layer, protecting the grate bars of the pallets during the sintering process. The product obtained from the process is a blast furnace feed of superior quality.

Environmental safety

Outotec sinter plants are designed to meet the most stringent environmental regulations. For effective dust collection, electrostatic precipita-tors and/or bag lters dedust the sinter waste gas and air from the plant dedusting system. We provide processes for limiting dioxin, SOx and NOx emissions, while incorporating noise at-tenuation equipment to meet local regulations.

Tata Iron and Steel Co., India, has already three Outotec sintering plants in operation.

Why sinter?

Sintering is the agglomeration of ne-grained iron ores for blast furnace burden preparation. Manganese ores can also be sintered before smelting in the electric arc furnace. Sintering produces a feed of extremely consistent quality in terms of its:

Chemical compositionGrain size distributionReducibilitySinter strength

n

n

n

n

More out of ore! 003

Energy savings and reduced emissions

What is more, CO and pollutants like SOx, NOx, dust and dioxins/furans are passed through the sinter layer together with the recirculated gas. While CO is post-combusted, substantially saving on solid fuel, the pollutants are partially retained in the sinter layer and/or thermically decomposed. In integrated steel plants about 75% of the CO2 emissions are generated in the blast furnace and about 12% in the sintering process. When following the international CO2 policy, the Kyoto protocol, and as there is only a minimum technical margin for CO2 reduction measures in the blast furnace, EOS brings signi cant bene ts for all steel plant operators.

Typical ow sheet of a sinter plant with EOS system.

Bleed in

Recirculationgas system

Fresh air supply system

EOS Emission optimized sintering for lower costs

Iron ore sintering creates substantial off-gas volumes, and treating these in order to meet increasingly strin-gent environmental standards is expensive. That is why we have developed the emission optimized sinte-ring process. EOS uses recycling technology to reduce off-gas volumes by 40 to 50%, resulting in smaller secondary gas treatment systems. This means:

Lower capital investmentReduced operating costs

Conventional sintering uses ambient air to transport heat within the sinter bed, requiring a high air ow rate. However, EOS takes advantage of the fact that only a part of the oxygen in the air is consumed for coke combustion. Therefore a part stream of the off-gas is recycled via the hood, enriched with ambient air to an oxygen content of 1314% and used as intake process air. This reduces off-gas volumes by about 4050% without affecting the sintering process.

n

n


High intensity mixing and nodulizing

Mixing and granulation is perform-ed in two separate high intensity mixers, which have the advantage of minor investment costs and space requirements, combined with an excellent mixing and granulation effect, especially for ne grained ores. The required amount of process water will be added to the two mixers in predetermined ratios by means of spray nozzles, in order to adjust the optimum moisture/permeability of the feed mix.

Ignition furnace for optimum maintenance and operation

Outotec ignition furnaces consist of standardized segments, each with straight refractory lined vertical side walls and a laterally-arranged special combustion chamber on each side. This design offers the optimum solution in terms of maintenance and operation:

Uniform ignitionHighly exible operation in

response to uctuations in material bed permeability

Possibility of operation with a high rate of excess air

High safety standards

n

n

n

n

Lurgi traveling grate

Our solution for sinter machine is a Lurgi traveling grate consisting of an endless chain of pallets. Its feeding station ensures a continuous supply of hearth layer and feed mix to the sinter machine. Both the feed bins for hearth layer and for feed mix are level controlled. Furthermore, the hearth layer bin is equipped with an adjustable gate, providing a hearth layer of a predetermined height. The feed mix hopper outlet is equipped with motorized gates for adjusting the amount of material to be discharged via a variable speed roll feeder. Ultrasonic sensors control the bed height level of the individually motorized gates. The roll feeder discharges the material onto a segregation plate. This is an inclined plate across the pallet width. Its inclination and positioning in relation to the material ow from the roll feeder is adjustable for:

Improved feed mix permeability, lowering power consumption

Optimum segregation of ne and coarse particles

Optimum formation of the material layer on the pallets

n

n

n

The variable speed roll feeder is mounted on a separate support with rails and wheels to permit roll-in and roll-out for maintenance purposes.

Longer lasting pallets Since our pallets only come into contact with one another on the horizontal section of the upper and lower track, wear is minimized. Durability is also enhanced through the separation of each pallet from the chain by a lifting and lowering sprocket at each station.

Proprietary equipment for control, quality, economy and safety

Each pallet comprises:

A cast pallet body, as a single unit or in three pieces

Exchangeable front plates Four roller sets, each set

containing one running roller and one pressure roller, both arranged on the same shaft

Grate bars made from high alloyed cast steel

Side walls of cast materialInsulating sections to pro

tect the pallet body

n

n

n

n

n

n


Discharge station for long service life

The sinter strand discharges the sinter onto a crash deck, specially designed and equipped with wear-resistant material, from where it slides into a spiked roll crusher whose crushing arms grind it to a maximum size of 200 mm. A mov-able grizzly carrier is also featured.

Direct charging to cooler improves cooling efficiency and reduces emissions

The material discharged from the sinter machine enters a chute with a round opening. A concave mate-rial layer is built up on the sides of the chute. While passing through the opening, the entire fraction is mixed. This mixed material falls onto a radially adjustable saddle, where the material is re-segre-gated, the coarse material being deposited on the rear part of the lower chute section while the ne material is deposited in the center. As the cooler moves, the material accumulates on it to form a slop-ing material layer, whose height is determined by the inner angle of repose of the sinter. Upon the with-drawal of the material, a core ow develops, large lumps from the rear settling on the bottom of the cooler, ne material in the middle and me-dium sized on top.

Efficient sinter cooling

While hot sinter is best cooled in a separate cooler, on-strand cooling can be applied in particular appli-cations. Our cooler features all of the essential attributes:

Annular arrangement of troughsCooling air pressed through

the sinterA bed height of 1.4 to 1.6 m,

minimizing the cooling air volumeHorizontal movement of the

cooler trough, with the trough bottoms following a dip rail at the discharge station The cooler trough wheels run on a circular rail supported by a concrete sub-base, which also serves as a wind channel for cooling air. While the cooler is driven by friction drive units via a segmented friction ring, cooling air fans are arranged outside the cooler. Spillage collecting plates underneath each cooler trough bottom plate retain all sinter spillage and discharge it to the collecting hopper. Special seal bars, individually supported on at spring plates, minimize cooling air leakages.

n

n

n

n

Height-adjustable wheels provide equalized, uniform wheel loads, while temperature optimized side wall clamping allows for thermo-expansions without stressing the cooler.

Natural segregation with the maintenance-free cascade classifier

Outotec's new cascade classi er, separating coarse from ne size iron ore sinter stream material, replaces the scalping screen in front of double roll crushers. It functions based on:

Natural segregation by drop ping or pouring material

Adjustable saddles (adjusted once during start-up phase), guaranteeing the removal of inadmissible coarse material from the separated nes The cascade classi er is almost maintenance-free, since it runs on stone box type saddles which do not touch the side walls. Coarse particles separated at the saddle front side are fed into the cold sinter double roll crusher, while ne material separated at the saddle far side by-passes the crusher and is mixed again with the crushed material underneath.

n

n

Energy savings together with reduced emissions:

Optimum permeability of the sinter layer on the coolerOptimal use of the cooling airMinimum spillage since sinter nes are held off the

trough bottomMinimum dust emission since sinter nes are covered

by the middle size sinter fraction, acting as a ltration layer

n

n

n

n


State-of-the-art control systems

Sinter plant in Middlesbrough, U.K.

Outotec sinter plant control systems include:

Return nes balance controlMaterial mixture computing and control with individual moisture controlBurn through-point control/sinter capacity controlIgnition furnace control with permeability measurement

These enable extensive supervisory control functions using standard distributed or open control systems (DCS/OCS). Such an architecture supports the addition of an operational layer above DCS/OCS for process management (level 3) including monitoring, analyzing, optimizing, simulating and pre-tuning level 2 controllers (process management) based on a dynamic computer sinter model.

Flexibility brings extra benefits

Our sinter plants are designed to cater for uctuating production requirements. To enable high production rates, some plants are designed for a speci c output of up to 45 t/24 h/m. For lower rates, plants can be operated with maximum energy savings and superior sinter quality.

n

n

n

n

R&D facilities providing economy and innovative technology

Outotecs long research pedigree, based on our ownfacilities in Frankfurt, Germany, forms the basis forthe successful design and construction of sinter plants.While test series yield speci c data for the optimum technical and economical design of commercial plants,pot tests determine the key ore mix parameters (spe-ci c sinter output as a function of the applied suction and required sinter quality) for use together with the ux and solid fuel. These parameters form the basis of sinter plant design. Our full range of R&D facilities test sinter properties to meet international standards such as ISO, ASTM, JIS and DIN.

Traveling grate dimensions36600 m reaction area25 m machine width

Capacity 0.156.5 million tpy in single unitsAvailability 330345 days/yearSpeci c production rates up to 45 t/24 h/m

Consumption figures (per ton of product sinter)Solid and gaseous fuel: 12501400 MJElectrical energy: 2832 KWhProcess water: 0.030.05 m3

Operational manpower (4-shift basis): 1620 men per day

Process parametersBasicity CaO/SiO2: 1.22.9Bed height: 500730 mmSuction: 130190 mbarReturn nes rate: 1825%

Product qualitiesISO-strength (+ 6.3 mm) 7580%RDI (-3 mm) 2832%FeO 58%

Sinter plant modernization a made-to-fit process

Our solutions are not only valid for new plants but also revamps, retro ts and capacity increases. To improve the ef ciency of existing plants we provide a number of alternatives, ranging from individual equipment re-placement to extensive plant rehabilitations, tailored to each customers speci c needs.

n

n

n

n

n

n

n

n

n

n

n

n

n

n

n

n

Plant modernization can include:

Replacement of obsolete equipmentUpgrading of sinter plantsConstruction of plant units and new

sinter plants with maximum leverage of the existing infrastructure

n

n

n


Facts about Outotec sinter plants

Copyright 2007 Outotec Oyj. All rights reserved.Outotec and More out of ore! are registered trademarks of Outotec Oyj.

[email protected]

3013

EN. P

inta

/Lib

ris,

Hel

sink

i, Fi

nlan

d. M

ay 2

007

Outotec, formerly Outokumpu Technology, is a worldwide technology

leader in minerals and metals processing, providing innovative and

environmentally sound solutions for a wide variety of customers in

minerals processing, iron and steel, aluminum and non-ferrous metals

industries. Outotec Oyj is listed on the Helsinki Stock Exchange.

Sinter

Documents

Transcript of Sinter