The recycling of metallurgical waste such as jarosite, which is an iron precipitate from the hydrometallurgical zinc production route, and electric arc furnace dust from the iron and steel industry, avoids landfilling of hazardous waste and opens up new opportunities to use them as secondary raw materials. More than 50 % of the electric arc furnace dust produced globally and the majority of jarosite as well is currently being dumped, although these residues contain valuable elements such as zinc, lead, indium, silver and iron. Especially metals, such as indium and silver, often enable an economical processing of the industrial waste. The doctoral thesis includes the detailed characterization of both residues as well as contained elements and the evaluation of a possibility to recover the valuable metals parallel to the base metals. Thermodynamic calculations, single studies of the roasting step and volatilization trials as well as thermogravimetry-differential thermoanalysis help to develop a concept for the recycling of jarosite and electric arc furnace dust. In the pyrometallurgical concept presented in the thesis, the main achievement is the development of a metal bath process for a combined treatment of both residues to realize a selective extraction of valuable metals. In addition to tentative trials and investigations in laboratory scale, the process has also been tested on an up-scaled system. The advantages of the present investigations are that two residues with similar compositions can be processed together, a so-called multi-metal-recycling takes place and thereby landfill costs can be avoided. The products of the process include a metal-compounds bearing off-gas, an iron-alloy as well as a slag. In addition to the development of the concept, hydrometallurgical investigations for further utilization of the main product, the dust out of the off-gas, were part of the doctoral thesis.
|Translated title of the contribution
|Recycling of jarosite and electric arc furnace dust in a combined process to recover valuable metals
|Published - 2018
Bibliographical noteembargoed until 01-02-2021