WELCOME

RECYCLING OF WASTE IN CHEMICAL AND OTHER INDUSTRIES,FLY ASH UTILIZATION

SEMINAR ON

PRESENTED BY GOWRI V PRABHU 1st MSc EVS

INTRODUCTION•Environmental management of hazardous waste has become a major concern in India as dumping of hazardous waste results in severe environmental impairment.

•The adverse effects of hazardous waste as well as the significant potential risks posed by them to the life and supporting systems are increasingly recognized.

• Rapid growth of industries in India has resulted in generation of increasing volume of hazardous waste. Both indigenously generated waste and those imported from other countries for recycling or reprocessing need scientific treatment and disposal.

INDUSTRIAL HAZARDOUS WASTE•Hazardous waste are being generated in the country by various industries.

•They can be categorized broadly into two categories.1) Hazardous waste generated in a country from various industries.2) Hazardous waste imported into or exported to a country.

• The hazardous waste can be categorized as recyclable when resource recovery is possible by reprocessing the waste

EXAMPLES OF WASTE GENERATED BY INDUSTRIES

WASTE GENERATOR

WASTE TYPES

Chemical Manufacturers

• Acids and Bases•Spent solvents•Reactive waste•Waste water•Organic constituents

Printing Industry •Heavy Metal Solution•Waste Inks•Solvents•Ink sludge•Heavy metals

Vehicle maintenance shop

• Paint wastes•Spent solvents•Acids and Bases

WASTE GENERATOR WASTE TYPES Paper Industry •Ignitable Waste

•Corrosive Waste•Ink waste including solvents and metals

Construction Industry •Ignitable Waste•Paint Waste•Spent solvents•Strong Acids and Bases

Cleaning agents and cosmetic manufacturing Industry

•Heavy metal dust and sludge•Ignitable Waste•Solvents•Strong Acids and Bases

Furniture and wood manufacturing Industry

•Ignitable Waste•Spent solvents•Paint wastes

Metal Industries • Strong Acid and Bases•Cyanide waste•Paint waste containing heavy metals

RECYCLING •Recycling involves the collection of used and discarded materials ,processing these materials and making them into new products.

•Recycling is a key component of modern waste reduction and is the third component of the "Reduce, Reuse, and Recycle" waste hierarchy.

•It reduces the amount of waste that is disposed ,thereby making the environment cleaner.

There are three major divisions of recycling techniques: chemical, mechanical and organic.

*Recycling - chemical - a chemical reaction used for the treatment and processing of waste.

*Recycling - mechanical - is the processing of waste with the help of a machine, for example, a waste grinder.

*Recycling - organic - is technique which includes fermentation, to produce fertilizers and fuels such as biogas.

RECYCLING STEPS

BENEFITS OF RECYCLING•Conserve resources for the future.•Prevent emissions of many greenhouse

gases and water pollutants.•Save energy.•Supply valuable raw materials to industry.•Create jobs.•Stimulate the development of greener

technologies.•Reduce the need for new landfills and

incinerators.

Examples of Recycling in industries

Recycling of scrap industrial impurities and products occurs on a large scale with different materials. It includes :

•Ferrous metals composed primarily of iron and used largely as feedstockfor electric-arc furnaces.• Nonferrous metals including aluminum , copper , zinc, lead,cadmium, tin, silver, and mercury.• Inorganic substances including alkaline compounds ,acids and salts .• Glass, which makes up about 10 percent of municipal refuse.• Paper, commonly recycled from municipal refuse.• Plastic, consisting of a variety of moldable polymeric materials and composing a major constituent of municipal wastes.• Rubber• Catalysts from chemical synthesis or petroleum processing.

Recycling in Chemical Industries

•Recycling of metals, some basic chemicals and polymers occur in chemical industry.

RECYCLING OF SULFURIC ACID• Some sulfuric acid is produced from 'spent' (used) acid and related compounds such as ammonium sulfate.

•The acid and compounds are usually in dilute solution which is evaporated under vacuum to produce concentrated solutions.  These are fed into a furnace with oxygen at about 1200 K to produce sulfur dioxide:

The sulfur dioxide is dried by passage through concentrated sulfuric acid. It is then oxidized to sulfur trioxide and hence sulfuric acid using the Contact Process.

RECYCLING OF HYDROCHLORIC ACID

• The steel industry is a major user of hydrochloric acid for the pickling process to remove impurities.  The industry uses a process known as pyrohydrolysis to recover the spent acid, which now contains a mixture of iron chlorides.

•The spent liquor is first concentrated in an evaporator, with dissolved HCl being given off and collected. 

•The concentrated liquor is then fed into a roaster at 800-1000 K which converts the iron chlorides into HCl and iron(III) oxide, the HCl again being collected. 

RECYCLING OF POLYMERS – PLASTICS•Plastics recycling technologies have been historically divided into two general types : Primary and Secondary.

Primary recycling involves processing of a waste/scrap into a product with characteristics similar to those of original product.

Secondary recycling involves processing of waste/scrap plastics into materials that have characteristics different from those of original plastics product.

Stages in the Recycling of Polymers:

INSPECTION

CHOPPING AND WASHING

FLOATATION TANK

DRYING

MELTING

FILTERING

PELLETIZING

Stages in the Recycling of Polymers:

1) Inspection  Workers inspect the plastic trash for contaminants like rock and glass, and for plastics that the plant cannot recycle.

2) Chopping and Washing  The plastic is washed and chopped into flakes.

3) Flotation Tank  If mixed plastics are being recycled, they are sorted in a flotation tank, where some types of plastic sink and others float.

4) Drying  The plastic flakes are dried in a tumble dryer.

5) Melting  The dried flakes are fed into an extruder, where heat and pressure melt the plastic. Different types of plastics melt at different temperatures.

6) Filtering  The molten plastic is forced through a fine screen to remove any contaminants that slipped through the washing process. The molten plastic is then formed into strands.

7) Pelletizing  The strands are cooled in water, then chopped into uniform pellets. Manufacturing companies buy the plastic pellets from recyclers to make new products.

RECYCLING OF METALS•Metal recycling involves Process of reusing old metal material, to make new products.

•The materials for recycling come from three sources.

• One is the waste material generated by the initial manufacture and processing of the metal.

• Another is waste material from the fabrication of the metals into products.

• The third, most commonly regarded by the public as recycling, is the discarded metal-based product itself (old scrap). 

SORTING

SHREDDING

MEDIA SEPERATION

SHEARING

BAILING

Stages in the Recycling of Metals[Ferrous Metals]

•Ferrous metals are mainly composed of iron and have magnetic properties. Steel, an iron alloy containing carbon, is among the most-recycled material in the world.

•Sorting: Because magnets attract steel, this metal can be easily separated from other recyclables like paper in a recycling facility with magnetic belts.

•Shredding: Shredders incorporate rotating magnetic drums to extract iron and steel from the mixture of metals and other materials.

•Media separation: Further separation is achieved using electrical currents, high-pressure air flows and liquid floating systems.

•Shearing: Hydraulic machinery capable of exerting enormous pressure is used to cut thick heavy steel recovered from railways and ships. Other cutting techniques, such as the use of gas and plasma arch, are sometimes employed.

•Baling: Iron and steel products are compacted into large blocks to facilitate handling and transportation.

Stages in the Recycling of Metals[Ferrous Metals]

FLY ASH• Fly ash is defined as “A finely divided residue that results from the combustion of ground or powdered coal and is transported from the combustion chamber by exhaust gases”.

CHEMICAL COMPOSITION OF FLY ASH

•Silica (SiO2)

•Alumina (Al2O3)

•Iron Oxide (Fe2O3)

•Calcium Oxide (CaO)

•Magnesium Oxide (MgO)

•Sulphur (S)

USES OF FLY ASH:

Fly ash as a building material

Fly ash in clay bricks

Fly ash in hollow bricks

Fly ash as a cellular concrete

Use as part replacement of cement / manufacture of cement

Fly ash in emulsion paints

PORTLAND CEMENT

•Owing to its pozzolanic properties, fly ash is used as a replacement for some of the Portland cement content of concrete.

•It greatly improves the strength and durability of concrete, the use of fly ash is a key factor in their preservation.

SOIL STABILIZATION

•Soil stabilization is the permanent physical and chemical alteration of soils to enhance physical properties.

•Using fly ash as a soil stabilizer can increase shear strength, Control the shrink-swell properties of soil and improve load bearing capacity.WASTE TREATMENT

•Due to its alkalinity and water absorption capacity, fly ash may be used in combination with other alkaline materials to transform sewage sludge into organic fertilizer or biofuel

BRICKS

•There are several techniques for manufacturing construction bricks from fly ash, producing a wide variety of products.

•Fly ash brick is made by mixing soil, plaster of Paris, fly ash and water, and allowing the mixture to dry. Because no heat is required, this technique reduces air pollution.

•More modern manufacturing processes use a greater proportion of fly ash, and a high pressure manufacturing technique, which produces high strength bricks with environmental benefits.

conclusion•Recycling waste not only save our natural resources but also help save energy.

•Recycling reduces the need for landfilling,incineration and also helps reduce pollution

•The Use of fly ash has grown nowadays and it is a common ingredient in concrete adding to its strength and durability.

•Fly ash has various other applications also like Soil Stabilization, Waste Treatment and Brick manufacturing.

THANK YOU