One solution for resources recycling-reduction of So₂ gas and Gypsum by waste plastics

This paper describes the new technologies for fixation of smelting So ₂ gas as elemental sulphur and for converting gypsum to recycled calcium resource using waste organic materials. To produce nonferrous metals, the So₂ gas is also generated from the raw materials such as sulphide or sulphate. A process that produces elemental sulphur from nonferrous smelter gas and waste plastics was investigated. Polyethylene was used as a deoxidiser of So₂ gas in the present study. The conditions for reaction of So₂ and polyethylene to make gas mixtures of H2S and So₂ were calculated thermodynamically. The Claus reaction was applied to produce elemental sulphur from H2S and So₂ gas mixture. More than 90 % sulphur recovered from So₂ gas. A recycle of calcium resources as CaO or CaS from the waste gypsum was developed with a reduction process of the gypsum using plastics at high temperature. Reduction behaviour of CaSo ₄ by polyethylene at temperature from 1,273 to 1,573 K was studied with gravimetry and X-ray diffraction analysis. From the experimental results, we found that complete reduction of CaSo₄ to CaO can be done at the molar ratio more than 3/1 of CH2/CaSo₄ for 2 h above 1,473 K, and increasing CaSo₄-CH2 gas interface tend to advance the reduction of CaSo₄.