The effect of properties of the suspension of copper processing tailings on shear yield stress and its significance to solids liquid separation

Shear yield stress as a rheological property of suspensions affects the efficiency of some of the mineral processing methods such as solids liquid separation, grinding, classification, and tailings disposal. In this work, effect of solids concentration, fines extent, pH and temperature on the shear yield stress of the final tailings suspension of concentration plant 1 at Sarcheshmeh Copper Complex was investigated and eventually their impact on solids liquid separation was analyzed. The shear yield stress was calculated using the slump test results and the analytical model presented by Pashias. Results indicated that, with the extent of fines the shear yield stress increased considerably. An increase in flocculant dosage up to 10 g/t resulted in a significant increase in the shear yield stress. While, with the flocculant dosages higher than 20 g/t, increasing the flocculant dosage led to a slight increase in the shear yield stress. An increase in shear yield stress leads to a decrease in compressibility of suspension and as a result the efficiency of solids liquid separation decreases. These achievements can be beneficial to the efficiency of thickening and filtering.