Lead electrowinning from methane sulfonic acid

Currently lead is produced by conventional pyrometallurgical smelting route which is suitable for high grade sulfide ores and concentrates. The hydrometallurgical recovery of lead through methane sulfonic acid (MSA) medium provides a green lead production route with a potentially lower cost. Electrowinning is the most feasible and economic way to produce lead metal in the hydrometallurgical route. The current challenge for lead electrowinning from methane sulfonate solution is to produce a smooth and dense lead deposit without the significant formation of PbO2 on an anode. The use of proper leveling agents is the key for production of high-quality electrolytic lead. Various additives were first investigated using a Hull cell and then by electrowinning. Aloe has the best leveling effect. The combination of aloe and glue can produce smooth and dense lead deposits. Several DSA anodes have been evaluated and some of them have an oxygen evolution overpotential low enough to prevent the formation of PbO2. Although the current efficiency of PbO2 on graphite can be reduced to 3.6% in the presence of H3PO4, graphite anodes were not stable and degraded after extended time of electrowinning. With the use of aloe and glue as smoothing agents and suitable DSA anodes, smooth and dense lead deposits can be produced without the formation of PbO2 on the anodes. Lead can be depleted to 3 g/L from the electrolyte at a high efficiency. The presence of 5 g/L Fe in the electrolyte resulted in a decrease of 2.1% in the lead current efficiency. Chloride at its level of 50 mg/L or less practically has no effect on lead electrowinning.

Automated summary

The hydrometallurgical recovery of lead through methane sulfonic acid provides a green and potentially cost-effective lead production route. Electrowinning is the most feasible and economic way to produce lead metal in this method. The primary challenge is to produce smooth and dense lead deposits without the significant formation of PbO2 on an anode.