Use of Waste Plastics in Coke Oven: A Review

Abstract

To help in building a recycling-oriented sustainable society, Nippon Steel & Sumitomo Metal Corporation developed a waste plastic-recycling process using coke oven and put it into commercial operation in 2000. Now roughly 200,000 tons per year of waste plastics are processed in coke oven in Japan. In this process, the waste plastics collected from households are agglomerated to the sizes ranging from 20 to 30 mm in diameter and charged into coke ovens with coal at the blending ratio of about 1 mass%. Waste plastics are thermally decomposed into approximately 20 mass% coke, 40 mass% hydrocarbon oil (tar and light oil) and 40 mass% coke oven gas, which are utilized as iron ore-reducing agents in blast furnaces, raw materials for the chemical industry, and a fuel for power plants, respectively. Moreover, 92 mass% of the chlorine in waste plastics is released and absorbed by the ammonia liquor spray for cooling hot coke oven gas and converted to ammonium chloride. The waste plastic-recycling process using coke ovens is superior in that a large amount of waste plastics can be treated, useful materials can be recovered using the existing facilities, coke quality can be kept the same and the chlorine released from waste plastics can be fixed in the existing ammonia liquor spray system.

Revealing the intersectoral material flow of plastic containers and packaging in Japan

“…Feedstock recycling technologies that currently work in practice in Japan, including gasification and coke oven and blast furnace feedstock recycling, are less demanding in terms of the quality of plastic waste including the resin composition than mechanical recycling. The only exception is that the ratio of polyvinyl chloride (PVC) and other chlorinated plastics needs to be lowered, especially in blast furnace feedstock recycling, because chlorine in plastic waste is considered to be decomposed into hydrogen chloride and to lead to the corrosion of facilities (56,57). On the other hand, PS shows higher coke and oil yields (85%) than other resin types (42%, 60%, and 33% for PE, PP, and PET, respectively) in coke oven feedstock recycling (56,58).…”

“…The only exception is that the ratio of polyvinyl chloride (PVC) and other chlorinated plastics needs to be lowered, especially in blast furnace feedstock recycling, because chlorine in plastic waste is considered to be decomposed into hydrogen chloride and to lead to the corrosion of facilities (56,57). On the other hand, PS shows higher coke and oil yields (85%) than other resin types (42%, 60%, and 33% for PE, PP, and PET, respectively) in coke oven feedstock recycling (56,58). In this context, plastic container and packaging inflow into manufacturing products and machinery sectors (0.77 Mt in total) with a higher proportion of polyolefin (SI Appendix, Fig.…”

Current state and future prospects of plastic waste as source of fuel: A review

“…This is supported by the studies on dechlorination kinetics, which showed that 99.5 wt% of HCl could be released at 300 1C when heated for 96 s, before the degradation of main hydrocarbon chain started [46,51]. Another dechlorination method is displayed by an operating plastic waste recycling plant in Japan, where ammonia spray is used for cooling of product gas while absorbing HCl gas [122]. Total elimination of chlorine is reported in such case.…”

Plastics—Villain or Hero? Polymers and Recycled Polymers in Mineral and Metallurgical Processing—A Review

“…Japan uses waste plastics to produce coke, coke oven gas (COG) and hydrocarbon oil in a coke oven [48,49]. Nippon Steel & Sumitomo Metal Corporation (NSSMC) successfully developed a commercial-scale waste plastic-recycling process in coke ovens that treats ≈200,000 tons per year of waste plastic [50]. In coke ovens, waste plastics are not burnt but decomposed to produce chemically useful materials that are easily recovered (Table 10).…”

“…Effect of adding various plastics (2% mass) on coke strength DI15150 (Adapted from [50], with permission from © 2015 Springer Nature).…”