The coke ovens, where waste plastic has found a new use

The Company’s pilot plant experiment has shown that usage of plastics till 0.5% of the mass in top charge blend has no adverse impact on the coke properties. This experiment was based on the experience of Nippon Steel Nagoya and Kimitsu Works in reusing plastics. Recycling of waste plastics was started by them in 2000. Enthused by these findings, the Company has begun using plastics in Stamp Charged Battery #8 and #9. The Company plans to gradually step up to 0.5% in all the batteries. Prior to its use, the Company conducted several tests to assess the feasibility of using it in top charging coal blends.

All synthetic products, including plastics affect the environment somewhere during their lifecycle, that is from the point of manufacture to disposal. While plastics are very versatile and therefore adapt easily to a variety of uses, their disposal is possibly the biggest challenge facing the world. They are non-biodegradable, difficult to destroy. However, they are easy to recycle.

Burning of plastics in not permissible as it causes severe pollution problems. The coking process is now considered a promising area to which thermal decomposition of waste plastics is applicable. This is because the process involves coal carbonisation at a high temperature in a reducing atmosphere.

Tata Steel conducted tests on the fluidity of coal blend; the quality of resultant coke produced; coke, tar and gas yields; and ash constituents. During laboratory tests as well as actual coke oven tests, the yield of coke, gas, tar and light oil were 20%, 40% and 40% respectively. The impact of 0.5% plastic addition to the base coal blend improved the strength of the resultant coke. At this range, the CSR of coke also improved. However, when a higher percentage of plastic was added the results were not very encouraging.

Alternative methods to recycle plastics have also been identified. If plastics are sorted and segregated then they can find use in a number of different areas. The West Bokaro unit of Tata Steel has effectively proved that waste plastic can be used to make ropes. Across the world, plastics have been recycled to make pencils and pencils leads, antirust paint and headlamp back cans for new cars.