Breakthrough in Zinc solution purification process

Blue Cube Systems is proud to announce the successful implementation of our newly developed In-line Hydromet unit, which is used in the zinc purification process.

The process chain of zinc production is illustrated below.

In the production of zinc metal, the zinc concentrates (from the mine) are roasted to convert the sulphide concentrates into zinc oxide. In the process sulphur dioxide gas is converted into sulphuric acid. Zinc oxide is then leached with the sulphuric acid, producing an impure zinc sulphate solution.

The next stage involves solution purification. In the first stage, copper is removed by precipitation with zinc dust. In the second stage, cadmium is removed, also by way of precipitation with zinc dust and copper sulphate.

The purified zinc sulphate solution is then pumped to the cell house. In the cell house, zinc metal is electrolytically plated onto aluminium cathodes.

The Blue Cube technology is applied in the first stage of solvent purification, where the copper is removed by precipitation with zinc dust.

The Blue Cube MQi instrumentation is used to measure Cu concentration, see the illustration below. The zinc dust dosing is controlled automatically to keep the Cu concentration at a set point value of 2 ppm. (Zinc dust is expensive and overdosing has financial implications.) Under-dosing results in too high a Cu concentration.

Due to the improved real time control, the subsequent cost saving from reduced zinc dust consumption, paid back the investment associated with the Blue Cube instrumentation in a short period.