RECYCLING OF WASTE IN CHEMICAL AND OTHER INDUSTRIES,FLY ASH

2. RECYCLING OF WASTE IN CHEMICAL
AND OTHER INDUSTRIES,FLY ASH
UTILIZATION
SEMINAR ON
PRESENTED BY
GOWRI V PRABHU
1st MSc EVS

3. 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.

4. 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

5. 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

6. 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

7. •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.

8. 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.

10. •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.

11. 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 feedstock
for 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.

12. •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:

13. 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.

14. 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.

15. INSPECTION
CHOPPING AND WASHING
FLOATATION TANK
DRYING
MELTING
FILTERING
PELLETIZING

16. 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.

17. 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.

18. 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).

19. SORTING
SHREDDING
MEDIA SEPERATION
SHEARING
BAILING
•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.

20. •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.

21. • 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”.

22. •Silica (SiO2)
•Alumina (Al2O3)
•Iron Oxide (Fe2O3)
•Calcium Oxide (CaO)
•Magnesium Oxide (MgO)
•Sulphur (S)

23. 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

24.  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.

25. 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

26. 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.

27. •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.