Study on mechanisms of different sulfuric acid leaching technologies of chromite

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2017-09, Vol.24 (9), p.983-990
• Main Authors: Shi, Pei-yang, Liu, Cheng-jun, Zhao, Qing, Shi, Hao-nan
• Format: Article
• Language: English
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Chromates; Chromite; Composites; Corrosion and Coatings; Glass; Irradiation; Leaching; Materials Science; Metallic Materials; Microwaves; Natural Materials; Oxidizing agents; Raw materials; Sulfuric acid; Sulfuric acid leaching; Surfaces and Interfaces; Thermal shock; Thin Films; Tribology
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-017-1486-2

The extraction of chromate from chromite via the sulfuric acid leaching process has strong potential for practical use because it is a simple and environmentally friendly process. This paper aims to study the sulfuric acid leaching process using chromite as a raw material via either microwave irradiation or in the presence of an oxidizing agent. The results show that the main phases in Pakistan chromite are ferrichromspinel, chrompicotite, hortonolite, and silicate embedded around the spinel phases. Compared with the process with an oxidizing agent, the process involving microwaves has a higher leaching efficiency. When the mass fraction of sulfuric acid was 80% and the leaching time was 20 min, the efficiency could exceed 85%. In addition, the mechanisms of these two technologies fundamentally differ. When the leaching was processed in the presence of an oxidizing agent, the silicate was leached first and then expanded. By contrast, in the case of leaching under microwave irradiation, the chromite was dissolved layer by layer and numerous cracks appeared at the particle surface because of thermal shock. In addition, the silicate phase shrunk instead of expanding.