Evaluierung unterschiedlicher Recyclingansätze für gebrauchte Feuerfeststeine aus der sekundären Kupferindustrie

Research output: ThesisMaster's Thesis

Abstract

In today's standard pyrometallurgical process route, copper matte is extracted in a so-called flash smelter, which is then further oxidized to blister copper in the converter and then subjected to fire refining in a rotary drum furnace or hearth furnace. The extraction process for secondary raw materials is similar, with the fundamental difference that instead of a flash smelter, furnaces operated under reducing conditions are used. Refractory materials are indispensable for these high-temperature processes. In the copper industry, mainly magnesia-chromium and alumina-chromium refractory materials are used. During the ongoing processes, intrusions from the melt into the material and chemical reactions occur, which change the composition of the refractory products. The refractory input materials and valuable metals can be recovered using mechanical treatment processes, flotation, volatilization of impurities and leaching processes. However, due to the complex composition of the residual materials and the low quality of the products, these are rarely used, which is why they currently mainly end up in landfill sites. The investigated refractory breakouts are magnesia-chromium bricks from a shaft furnace and alumina-chromium bricks from a converter and a hearth furnace in the secondary copper industry. After a comprehensive characterization, different approaches for recovering the fractions of refractory material and valuable metal were evaluated. These include coarse comminution with subsequent sieve analysis, the determination of magnetic properties and leaching tests. According to the results of the characterization, the greatest changes in the material occur on the inside of the furnace. This is where the highest levels of copper and other intruded metals occur. These decrease towards the cold side, where no noticeable changes in the stone are recognizable. Copper is largely contained in the materials in oxidic form, but it also reacts with the refractory material and forms various compounds. According to the sieve analysis, a coarse sieve cut after crushing would be worthwhile to separate any adhering metal pieces. The results of the susceptibility analysis show that the separation of a ferromagnetic fraction is possible. The extraction rates for copper are highest in the leaching tests at temperatures of 90 °C, a pH value of 0.3, a leaching time of 120 minutes and a solid to liquid ratio of 1:15. In order to optimize hydrometallurgical recovery, suggestions for improvements to the setup and ideas for further investigations are discussed.

Details

Translated title of the contributionEvaluation of different recycling approaches for used refractory bricks from the secondary copper industry
Original languageGerman
Awarding Institution
Supervisors/Advisors
Award date28 Jun 2024
Publication statusPublished - 2024