Research on use of waste plastic as a reducing agent substitution in a material manufacturing process

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We performed a basic research on the use of waste plastics aiming the reduction of carbon dioxide emission of current 10 million tons a year from the metal industry. This year, we investigated the reduction of chromium employing solid carbonaceous fuels obtained from the dechlorination of waste plastics. We examined also the production of syngas (carbon monoxide and hydrogen) from PET, which can not be converted into oil by pyrolysis. All these processes were used to investigate their effect on the carbon dioxide reduction. Mixtures of powdered dechlorinated waste plastics, chromium slag and silicon sand were used as input material. These materials were heated in an alumina boat from room temperature to the process temperature. After that, the sexivalent chromium dissolution test was carried out with hydrochloric acid as an eluent. The yield of syngas (carbon monoxide and hydrogen) obtained by steam reforming of PET in the presence of calcium hydroxide and nickel oxide was determined. The results were compared with the use of coal in order to evaluate the effect of the substitution of fossil fuels by waste plastics and the resulting carbon dioxide reduction. After heating at 1000 ℃ in oxygen atmosphere, 1.6 % of sexivalent chromium was leached out of the sample but, after heating between 600 ℃ and 1000 ℃ in helium atmosphere, just 0.5 % was leached. These results show the possibility to substitute oil coke by dechlorinated waste plastics during the chromium slag treatment. One main product of syngas obtained from PET and PC by the pyrolysis in the presence of calcium hydroxide and nickel oxide, carbon monoxide can be used as reduction agent in the production of several metals, e.g. steel. The other main product of syngas, hydrogen is an important energy source in future technologies.