Canmet's Project on the Chemistry, Generation and Treatment of Thiosalts in Milling Effluents

Dissolution Test Protocol for Estimating Water Quality Changes in Minerals Processing Plants Operating With Closed Water Circulation

“…The dissolution at a high temperature tended to decrease the pH. A possible explanation for this might be that temperature enhanced the oxidation of sulfur-reduced compounds to a higher degree of oxidation, such as sulfite, thiosalts, and sulfate, which resulted in an acidification of the pulp [27]. According to this data, we could infer that changing the operating conditions of the plants should be considered according to temperature variation.…”

“…Indeed, the process water pH varies mostly around 7.5-8.5, while the pH of the water from the dissolution loop varies mostly around 8-9. That is a direct consequence that our test did not simulate the tailings pond of the plan, which is the location when the oxidation reaction of sulfide occurs continuously and, as a consequence, reduces the pH [27,34]. At this slightly basic range of pH, a slight increase in pH could strongly decrease the solubility of metal hydroxides [35].…”

“…However, the disadvantages exist: the synthetic water matrix is mostly stable, oversimplified, and the ore might never get into contact with such a water matrix in the true plant. The complexity, dynamicity, and instability of mining process waters have been highlighted by many researchers [2,9,27,34,39,40].…”

Chemical Oxidation Methods for the Treatment of Thiosalt-Containing Mill Effluents

“…Here, a more reliable chemical treatment method may be required to replace or complete bacterial oxidation. The present study focusses on three low temperature industrial treatment options, because more energy intensive operations are precluded given the sheer volume of BMS effluent (up to 20 m 3 /min, containing < 3 g/l of thiosalts) [1,2].…”

“…Difficulties arise where limited storage area is available, and where process/climatic conditions are unfavourable for bacterial activity. These problems are exemplified in extensive studies [1][2][3][4][5] J undertaken in relation to the Brunswick Mining and Smelting (BMS) operation near Bathhurst, New Brunswick. Here, a more reliable chemical treatment method may be required to replace or complete bacterial oxidation.…”