Effect of Zinc Sulphide Concentrate Composition and Roasting Temperature on Magnesium Distribution in Zinc Calcine

Magnesium removal in the electrolytic zinc industry

“…In that case, the prediction of the distribution of magnesium over the respective phases based on the chemical composition of the concentrate and the reaction temperature in the roaster is particularly useful [18] . When a substantial part of magnesium is present in zinc ferrites, Ausmelt submerged lance technology could be applied.…”

“…For these reasons, the magnesium level must be controlled between 10 and 15 g/l. [18], [19], [20] The only 'natural' magnesium bleed in the process is solution losses (e.g. entrapped liquor in iron precipitates).…”

“…Thermodynamic calculations of this system showed that it is possible to predict the distribution of magnesium over the respective phases based on the chemical composition of the concentrate and the reaction temperature in the roaster. [18] The average magnesium content of zinc concentrates is not particularly high (typically 0.2wt% [7] ), but as there is hardly any natural magnesium bleed, accumulation can occur in process liquors (up to the saturation level if no measures are taken). When magnesium is allowed to accumulate to 8 g/l at a current density of 600 A/m 2 , the voltage drop per cell increases by 0.2 V due to reduced conductivity of the solution.…”