Application of clay-rich full plant tailings paste backfill technology

摘要

Jiashi Tonghui Copper Mine (JTCM) is located in Kashgar District, Sinkiang, China. In the presence of water, the ore and rock of this copper mine are easy to slime. In this situation, paste backfill with the advantage of no bleeding has become the required filling method. However, the content of magnesium silicate clay minerals in the unclassified tailings reaches 72.28%, which is two to seven times more than other mines. Paste backfill application in this mine was faced with three technical problems: (i) slow settling and difficulties with thickening, (ii) low strength and large consumption of cement, and (iii) high yield stress and difficulties with transport.This paper introduces several solutions to the above problems. Firstly, a suitable flocculant which matches mineral properties was selected and a secondary flocculant dilution system was added to improve the settling rate of clay-rich unclassified tailings. Thus, an underflow concentration of 70-72% can be achieved. Secondly, Gobi aggregates were added to optimise slurry gradation. By this means, paste concentration increased from 75-80% and the strength increased by five times. Thirdly, adding pumping admixtures can reduce the yield stress of high-concentration slurry by 45% and decrease the plastic viscosity by two times. The paste slurry was transported over a distance of 2.6 km by a high-pressure (15 MPa) plunger pump. Based on this, long-distance transportation of paste with high clay content and high viscosity can be achieved.