Feasibility study on use of high-salt wastewater of power plant as part of washwater of Panji Coal Preparation Plant

Panji Coal Preparation Plant is operating with inadequate supply of washwater while Panji Power Plant finds it difficult to treat the high-salt wastewater it produces. To address the issue, an analysis is made of the quality of the wastewater of the power plant and the circulating water of the coal washery. Based on the analysis result, test on dosage of reagent in flotation of slime and test on flocculating settling of sedimented slime in the instances of using the wastewater and circulating water are both conducted. Test results show that the wastewater of the power plant contains high proportion of Ca²⁺ and Mg²⁺ ions with a hardness 7.36 times higher than the circulating water; the exclusive use of wastewater in flotation of slime can lead to somewhat reduction of yield of flotation concentrate, and its use in combination with the circulating water can well meet the general requirement as a good flotation result can be assured; compared with the circulating water and water for domestic use, the use of the wastewater can effectively lower the turbidity of the clarified water after the solid particles are sedimented; the wastewater can be used as make-up water for Panji coal washery in controlled proportions, and when it is used as a half of the amounts of washwater, 1.401 million yuan of water cost can be saved a year; the use of the wastewater as partial washwater proves to be practically feasible, which can not only meet the requirements of slime flotation and sedimentation processes, but also make it possible to ease the difficulty in treatment of high-salt wasterwater, and effectively improve the economic performance of Panji plant.