What are the Factors that Affect Anode Life?

In electrowinning, metals ions dissolved in an electrolyte are deposited in a reduced metallic form at the cathode. The conversion of the metal from an ionic (dissolved, positive charge) to metallic form (solid, no charge) at the cathode requires a supply of electrons into the electrolyte solution which is supplied from the anode.

Electrowinning is a very convenient and robust way to directly recover dissolved metals such as copper, silver, gold, nickel, cobalt, and tin from their aqueous states in a particular electrolyte.  Not surprising then when talking about metal recovery that we tend to focus most of our attention on those metals that we are interested in with the aim of recovering them from solution.  That is after all the objective of the metal recovery process.  What is less often talked about however are the impurities that can affect metal recovery with electrowinning.  This blog post will identify those impurities that are most detrimental and discuss their effect on the electrowinning of some commonly recovered metals from aqueous solutions. 

As the world is advancing towards clean, sustainable energy sources, businesses in traditional resource industries can be faced with a moral dilemma – to sacrifice margins in favour of clean initiatives or continue using conventional equipment and carbon-based energy sources that ensure revenue maximization.

The electro-refining of copper is a multi-step process that starts with copper concentrate that is smelted to produce impure copper anodes, which are then electrorefined to produce LME Grade A copper cathode (+99.99%).  A simplified block flow diagram of copper refining is shown below.

Silver refining is a critical part of any precious metals refinery.  Often the higher value metals such as gold and the Platinum Group Metals (PGM’s) are associated with silver, which must be recovered separately as a by-product.