Investigation of the sphalerite oxidation leaching by pyrolusite in chloride and sulfate medium

Document Type : Research Article

Authors

1 Amirkabir University of Technology (Tehran Polytechnique)

2 Department of Mining Engineering,, Amirkabir University of Technology (Tehran Polytechnique)

3 Amirkabir University of Technology

Abstract

The most important resource for zinc metal is sulfide ores which have a dissolution problem due to an inactive layer of sulfur on their surface causing the low leaching efficiency. Extensive research has been done to dissolve sphalerite in an acidic environment with various oxidants such as oxygen. In most of these researches, disadvantages such as the high cost of oxidant production, high investment cost, high depreciation of equipment, and environmental hazards are observed. In this research, acidic leaching of a sphalerite concentrate, which contains 41.235% zinc, 26.24% sulfur, and 6.6% iron, by pyrolusite in sulfate and chloride medium has been investigated. The investigated parameters include pyrolusite concentration, acid concentration, temperature, time, and solid-to-liquid ratio, each of which has been investigated at 5 levels. According to the results, the efficiency of zinc leaching reaches 85% by increasing the temperature from 25 to 85 °C. By reducing the ratio of solid to liquid from 150 to 50 g/L, zinc efficiency reaches 99.78%. Also, the sulfate leaching medium is more efficient than chloride. Comparatively, the zinc efficiency of the chloride medium has decreased by 22% in comparison with the sulfate medium under the same conditions. In the optimum condition, the efficiency of zinc leaching during 5 h reached 99.87%.

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