Electrorefining of Crude Solder for the Production of Fine Solder in Methanesulfonic Acid Medium: Electrolyte Conductivity and Electrorefining Process.

At present, the refining of crude solder has many drawbacks such as high energy consumption, high environmental pollution, equipment corrosion, and low current efficiency. Therefore, a new technique for refining crude solder is of great practical importance. In this work, the electrorefining of crude solder in methanesulfonic acid (MSA) medium was studied. The conductivities of tin-MSA solutions had been measured and modeled to characterize the electrolyte. The effects of the electrorefining conditions on the electrorefining process were investigated systematically. The cell voltage, current efficiency, and fine solder appearance were used to characterize the electrorefining performance. Some operating parameters of the electrorefining process are established as follows: current density 207 A/m(2), tin concentration 120-160 g/L, free-MSA concentration 90-120 g/L, electrode spacing 4 cm, and temperature 305.15-315.15 K. Under these conditions, the average cell voltage is 0.30 V and the current efficiency is 99.31%. The total content of tin and lead of the fine solder with good product appearance is >99.99%. This technique offers low energy consumption, high productivity, and low environmental pollution.