Research on Primary Water Hardness of Coal Slurry

摘要

We analyzed the composition, size of fine coal and ion concentration in coal slurry from 18 coal dressing plants. The results show that the water hardness of coal slurry can either change (increase or decrease) or remain stable during coal washing. This finding violates the common understanding that water hardness can only increase with coal slurry recycling. In this study, we analyzed the relations between water hardness and the settling performance of coal slurry, and calculated the interaction energies between coal particles in coal slurry suspensions under the different conditions of water hardness. The results show that water hardness is the determining factor in slurry settling performance; the higher the water hardness, the better the settling performance. On the basis of this research, we propose the new concept of primary water hardness and means of classification. Based on primary water hardness versus settling performance, we developed a mathematical model of calculating primary water hardness of coal slurry in coal preparation.