The possibility of recovering indium metal from acidic solutions by cementation

Indium recycling by a hydrometallurgical method must include the reduction of the dissolved ionic In compound to its metallic state. We have examined the easily implemented cementation of In with Fe, Zn, Mn, Al and Mg. It was found that the cementation with Zn turns slow as the produced layer lacks sufficient porosity to allow the solution to reach the metal surface, and the strongly adhering deposit is hard to be removed. On the other hand, Al may perform efficiently if the pH is set correctly. The indium layer is fast growing, can be easily removed. After mechanical compacting, it is easily melted. The Al consumption is close to the stoichiometric value at pH 1 and the produced indium sponge can be of 99.99% purity.