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

我们对废塑料的利用进行了基础研究，目标是减少金属工业目前每年1000万吨的二氧化碳排放。今年，我们研究了利用从废塑料脱氯中获得的固体碳质燃料来减少铬的问题。我们还研究了从PET生产合成气（一氧化碳和氢气），它不能通过热解转化为油。研究了这些工艺对二氧化碳减排量的影响。以脱氯废塑料粉、铬渣和硅砂的混合物为原料。这些材料在氧化铝容器中从室温加热到工艺温度。然后，以盐酸为洗脱液进行六价铬溶出试验。测定了在氢氧化钙和氧化镍存在下，PET水蒸气重整制得的合成气（一氧化碳和氢气）的产率。为了评价废塑料替代化石燃料的效果以及由此产生的二氧化碳的减少，将结果与煤炭的使用进行了比较。在氧气气氛中1000℃加热后，六价铬的浸出率为1.6%，而在氦气气氛中600 ~ 1000℃加热后，浸出率仅为0.5%。结果表明，脱氯废塑料在铬渣处理中替代油焦是可行的。在氢氧化钙和氧化镍的存在下，由PET和PC热解得到的合成气的主要产物之一是一氧化碳，它可以作为还原剂用于生产几种金属，如钢。氢气是合成气的另一个主要产品，是未来技术的重要能源。

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.