Electrowinning of tellurium from alkaline leach liquor of cemented Te

The electrochemical behaviour of tellurium in 2.5 M NaOH solution was studied for the recovery of tellurium from alkaline leach liquor of cemented Te using steady state polarization and cyclic voltammetry. The deposition characteristics and the potential range for a stable deposit of tellurium were also investigated. The morphology of deposited Te in alkaline solution showed a very porous nature and needlelike radial growth. The potential range for stable electrodeposition was between -0.8 V and -0.95 V (vs Hg/HgO electrode), but electrowinning could be carried out at more negative potentials due to the disproportionation reaction of Te-2(2-). Laboratory-scale electrowinning experiments were performed under different operating voltages, temperatures and initial Te concentrations. The current efficiency was about 85-90% for 50% recovery and about 50-60% for 90% recovery. The purity of electrodeposited Te was higher than 99.95%.