Thermodynamic analysis of decomposing Bi2S3 in acidic system and its application in treatment of molybdenite-bismuthinite mixed ore.

• The E-pH dominant region diagrams of Bi-S-H 2 O and Bi-S-Cl-H 2 O systems were drawn. • The mechanism of decomposition of Bi 2 S 3 by HCl was revealed according to thermodynamic analysis. • The experiment result proves the accuracy of the theoretical prediction and provides support for the separation of molybdenite and bismuthinite. Through thermodynamic calculations, the E-pH diagrams of the Bi-S-H 2 O and Bi-S-Cl-H 2 O systems at 298 K were plotted, the dominant regions of the components in the system and their changes with pH were clarified, and the mechanism and thermodynamic conditions for the decomposition of Bi 2 S 3 in acidic systems were clarified. The key to the decomposition of Bi 2 S 3 in acidic systems was based on the coordination of Cl− and Bi3+. The formation of BiCl 4 − can promote the decomposition of Bi 2 S 3 in acidic systems, based on this characteristic, HCl was used to achieve efficient leaching of bismuth in molybdenite-bismuthinite mixed ore. Under the optimized conditions of hydrochloric acid concentration of 6 mol/L, liquid-to-solid ratio of 5:1, temperature of 95 °C, stirring speed of 400 rpm, and time of 300 min, the leaching efficiency of bismuth reached 97.64 %, and the bismuth content in the leaching residue was 0.93 %, while molybdenum remained in the form of MoS 2 in the residue, The efficient separation of molybdenum and bismuth has been achieved, providing a new process to solve the traditional separation of molybdenite-bismuthinite mixed ores. [ABSTRACT FROM AUTHOR]