Prozessentwicklung zur metallurgischen Verwertung von Elektroaltgeräten

Research output: ThesisDoctoral Thesis

Organisational units

Abstract

The usage of electrical and electronic devices occupies an essential part in nowadays society. When they exceed their lifespan they accrue as waste electrical and electronic equipment (WEEE) respectively e-scrap. About 50 Mt of these wastes arise annually, which is increasing steadily. Due to the amount of different recyclables their recovery form a big advantage, especially regarding metals like copper and the precious ones. Challenges for the establishment of such a recycling process are the variety, complexity and the content of hazardous substances of these scraps. Possibilities for the dealing with WEEE are diverse mechanical processing steps followed by various pyrometallurgical as well as hydrometallurgical methods, preferably to recover valuable metals.
Regarding smelting of e-scrap there are different aspects, which must be considered. The heterogeneity and the partly low content of valuable elements of this feedstock impede the implementation of such a process that is economic acceptable. Therefore, smelting experiments were performed under diverse conditions with different fractions of WEEE, in order to collect the valuable metals in an alloy respectively to increase their yields. Further, the behavior of the slag was also investigated to gain information about emerging phases and especially the melting point. An additional important aspect is the generated off-gas during pyrometallurgical processing of e-scrap. Due to the content of hazardous substances the danger of the formation of halogenated dioxins and furans is given. Therefore, a proper post treatment must be implemented to prevent this and in particular remove the halogens. This can be managed by establishing a suitable off-gas system including a scrubber unit.
Further processing of the gained alloy can be performed hydrometallurgically. A leaching (especially pressure leaching) step depicts a substantive method to separate diverse elements. In principle, investigations considering different agents, varying concentrations, temperatures and reaction times were carried out. The main goal was to dissolve copper in order to regain it in pure form by a subsequent electrolysis. Precious metals should be kept in the residue to recover them otherwise.
Based on these various methods there are many possibilities to handle WEEE and bring diverse valuable elements back in the material cycle. A suitable treatment is essential to sustainably improve the economic and ecologic consequences.

Details

Translated title of the contributionProcess development for metallurgical recycling of waste electrical and electronic equipment
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
Publication statusPublished - 2018