This process, widely diffused in the mining industry, relates to electro-metallurgy applications. It consists of the deposition of an electrolytic cell at the Cathode, in the metal you want to obtain. The most diffused electro-winning processes are those related to Copper, Zinc, Cobalt and in smaller measure Silver.
The solution coming from the mineral’s acid attack which contains the salts of the metal, generally sulphates or chlorates and sometimes nitrates, is electrolysed in baths - called “tanks” - which contain numerous Cathodes and Anodes. When the thickness of the Cathode has reached a sufficient value, usually about 1 cm, Cathodes are extracted and the metal is collected. Anodes have the function of allowing the evolution’s reaction of oxygen and chlorine in the case of hydrochloric solutions.
The Anode alloy of Pb-Sn-Ca is used in solutions of sole Sulphates, which is cheap and long-lasting. There are some limited applications where activated Titanium is used, when work at a high current density is required or to avoid Lead pollution. Copper, Nickel, Zinc and Cobalt electro-winning all belong to this group.
For solutions containing Chlorides the use of activated Titanium is mandatory, as the evolution of Chlorine would destroy the Lead’s Anode. Normally these solutions contain a mix of Chlorates and Sulphates in order to optimise the Cathode product. Nickel and Cobalt are produced with this process.
Finally, Silver is obtained from Nitrate solutions. Also in this case the ideal Anode is activated Titanium, as Nitric acid would quickly dissolve the potential Lead Anode.
Chemical Newtech is able to supply both new Anodes and the re-coating and repair service for Anodes used for all of the above processes, in particular the formulation of the coating for Chlorates and for that of Nitrates has been designed to have a long duration and a low energy consumption allowing to reduce power expenses over the lifecycle.