Hydrogen as Carbon-Free Reducing Agent in Non-ferrous Slag Fuming

In this work, pyrometallurgical treatment of non-ferrous iron residue was studied. This approach aimed to recover the valuable metals and convert the residue into reusable benign slag using hydrogen as a non-fossil reducing agent. The pyrometallurgical treatment for this type of residue involves pretreatment prior to two stages, oxidation and reduction. Hydrogen was employed as a reducing agent in slag cleaning. The reduction tests were performed at temperatures of 1200 degrees C, 1250 degrees C, and 1300 degrees C using H-2 and N-2 gases to form the reducing gas atmosphere. The results show that H-2 is an effective reductant because reduction proceeded rapidly, forming speiss droplets within the slag already after 10 minutes. The laboratory-scale experiments suggest that slags or other residues obtained from metallurgical processes can be further cleaned in a fuming process using hydrogen and its mixtures to obtain environmentally friendly cleaner slag with respect of volatile metals. The results also show that one can tune the reduction and control the formation of metallic iron during the process. Thermodynamic modeling was also performed to simulate the fuming stage, i.e., reduction of the slag. Metal alloy formation as well as elemental distributions between metal and slag were studied, and results from thermodynamic modeling agree well with experimental results.

Automated summary

This study focuses on the pyrometallurgical treatment of non-ferrous iron residue using hydrogen as a reducing agent. The results demonstrate that hydrogen is an effective reductant and can be used to recover valuable metals and convert the residue into reusable benign slag. Thermodynamic modeling also agrees well with experimental results, indicating the potential application of this method.