Carbothermal Reduction of Barium Sulfate-Rich Sludge from Acid Mine Drainage Treatment

Autor: S. Motaung, Jean Mulopo
Rok vydání: 2013
Předmět:
Zdroj: Mine Water and the Environment. 33:48-53
ISSN: 1616-1068
1025-9112
DOI: 10.1007/s10230-013-0240-x
Popis: The alkali–barium–calcium (ABC) desalination process is basically an integrated lime/limestone neutralisation process combined with a sulfate removal stage using barium carbonate (BaCO3), and a sludge processing stage. The BaSO4/CaCO3 sludge generated during the desalination stage is treated to recover BaS and CaO by dewatering and thermal processes, with the ultimate goal of producing sulfur and recovering BaCO3. BaCO3 is the main raw material used for sulfate removal and its recovery ensures that the ABC process is environmentally and financially sustainable. South Africa is also a large importer of sulfur. We evaluated the optimum conditions for the thermal treatment of BaSO4/CaCO3 sludge to recover by-products. A high temperature tube furnace was used to reduce BaSO4/CaCO3 sludge obtained from a pilot plant test conducted at a gold mine shaft. We used response surface methodology to investigate the combined effects of relevant process variables (time, temperature, and the carbon/barium sulfate (C/BaSO4) molar ratio to maximize the reduction of BaSO4/CaCO3 sludge. At optimal process conditions (T = 1,028 °C; molar ratio of C/BaSO4 = 2.8 mol/mol), the tube furnace yield of BaS from waste sludge was over 78.5 % after 35 min. Furthermore, the results were similar to those generated by roasting a laboratory-grade mixture of barite and calcite concentrates.
Databáze: OpenAIRE
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