Anode electrolysis of sulfides

Abstract

Traditional sulfide metallurgy produces harmful sulfur dioxide and is energy intensive. To this end, we develop an anode electrolysis approach in molten salt by which sulfide is electrochemically split into sulfur gas at a graphite inert anode while releasing metal ions that diffuse toward and are deposited at the cathode. The anodic splitting dictates the “sulfide-to-metal ion and sulfur gas” conversion that makes the reaction recur continuously. Using this approach, Cu 2 S is converted to sulfur gas and Cu in molten LiCl-KCl at 500 °C with a current efficiency of 99% and energy consumption of 0.420 kWh/kg −Cu (only considering the electricity for electrolysis). Besides Cu 2 S, the anode electrolysis can extract Cu from Cu matte that is an intermediate product from the traditional sulfide smelting process. More broadly, Fe, Ni, Pb, and Sb are extracted from FeS, CuFeS 2 , NiS, PbS, and Sb 2 S 3 , providing a general electrochemical method for sulfide metallurgy.

An electrolysis–displacement–distillation approach for the production of Li, Mg, Ca, Sr, and Ba metals

“…Scientific advances have been made in the field of high temperature molten salt electrochemistry for clean metal extraction. [21][22][23][24][25][26] Later, the success of the aluminum smelter (Hall-Héroult cell) brought Al products into our daily life. In the Hall-Héroult cell, molten cryolite dissolves Al 2 O 3 that is then electrochemically split into liquid Al at the bottom of the cathode and CO 2 at a carbon anode.…”

One-step separation and recovery of copper and sulfur by electrolysis in deep eutectic solvents

“…In the contemporary industrial landscape, sulfur dioxide (SO 2 ) emissions from sulfide metallurgy rank second only to those from coal-fired power plants. 1 Copper, the most abundant sulfurophilic metal, primarily exists as chalcocite (Cu 2 S) and chalcopyrite (CuFeS 2 ) in the Earth's crust. Consequently, copper pyrometallurgy stands as the leading source of SO 2 emissions within the metallurgical industry.…”

Repurposing Ni and Co from Alloy Scraps for the Synthesis of LiNi0.6Co0.2Mn0.2O2 Cathodes

“…Molten salts are prospective mediums for extractive metallurgy and metal separation because of their wide electrochemical window, low cost, and environmental friendliness. − In molten salt, electrochemical reactions can be used to break the chemical bonds or enable dissolution/deposition at a rapid rate because of the high temperature and corrosivity. − Zhong et al separated the components of aluminum alloys through an in situ anodic precipitation method in molten NaAlCl 4 , which was simple, fast, and efficient. Jiao et al efficiently separated and purified Ti from Cu–Ti alloys by selective electrochemical dissolution and deposition processes in NaCl–KCl melt at 750 °C.…”