Chemical recycling of PVC-containing plastic waste for recycling of critical metals

Abstract

Chemical recycling of polyvinyl chloride containing plastic waste to recover critical metals is a promising way to solve two important problems (polyvinyl chloride disposal and critical metal recovery) in waste management and is being transferred on a larger scale in the “CHM-Technology” project. Various polyvinyl chloride containing plastic wastes were pyrolyzed to generate a hydrogen chloride rich vapor. This hydrogen chloride rich vapor is used in a second step to chlorinate indium in liquid crystal displays. Indium chloride has a lower boiling point than indium-tin-oxide and evaporates. This is cooled down and generates a metal concentrate together with the decomposed volatile materials from liquid crystal displays. The chlorine content in the polyvinyl chloride containing plastic waste residues is reduced. The products solid, oil, hydrochloric acid and gas can be used for new products. For metal purification the metal concentrate is mixed with water, filtrated, distilled and an electrolysis is carried out to recover metallic indium. Nine waste containing PVC were used with significant differences: when more hydrochloric acid and less volatile organic fraction was produced, more indium was transferred to the metal concentrate. The best recovery of indium (78% purity after electrolysis) was 39 wt-% from LCD panels containing 83 mg In/kg.