Research And Design Of Water Treatment Technology For A Mine In Hebei

The mine water discharge in a mining area in the south of Hebei is 6000 m³/d,the suspended solid content in the mine water is 350³80 mg/L,the total dissolved solids is1709.7 mg/L,and the hardness is 83.2 mg/L?calculated as CaCO₃?.In order to make the quality of the treated mine water reach the requirements of the mine for the reuse of water,meet the effluent TDS?200 mg/L,the total hardness?10 mg/L,the recovery rate?85%,through the experimental research and program comparison,determine the best process and parameters,and complete the process design.The results of coagulation sedimentation test showed that when the dosage of PAC was 170 mg/L and the dosage of PAM?anionic?was 0.6 mg/L,the turbidity of precipitated water was 4.6 NTU,and the removal rate was 98.7%.Since the dosage of PAC is too high in the coagulation sedimentation method,it is considered to be treated by secondary coagulation and precipitation method:when a coagulation is added with100 mg/L PAC,and secondary coagulation is added with 20 mg/L PAC+0.6 mg/L anionic PAM,the turbidity of precipitated water was 4.6 NTU,and the removal rate was98.7%.The dosage of PAC by secondary coagulation and precipitation method was reduced by 29.4%compared with coagulation sedimentation method.The lime softening test was carried out under the optimal test conditions of the secondary coagulation and precipitation method.When the dosage of Ca?OH?₂ was 120 mg/L,the turbidity of the precipitated water was 14.3 NTU and the hardness was 43.3 mg/L.The removal rate was 47.9%,except for the low hard efficiency and increased effluent turbidity and sludge volume.The water sample treated by the secondary coagulation and precipitation method was softened by using 001×7 sodium cation exchange resin.The working exchange capacity of the resin was 945.8 mmol/L,considering that the mine water quality of the project is low and the softening water quality is high,the ion exchange method is finally selected to soften the mine water.Through the comparison of the clarification tank,filter and desalination process commonly used in the current project,the comprehensive consideration of the treatment process is:pre-sinking adjustment tank?hydraulic circulation clarification tank?ordinary quick filter?intermediate pool?ultrafiltration system?sodium Ion exchanger?high efficiency reverse osmosis system.According to the process flow,engineering design calculations were carried out.The total investment of the mine water treatment project is 6.5206 million yuan,the treatment cost is 1.89 yuan/ton of water,and the treated mine water is reused in the various water systems of the mining area to solve the problem of water shortage in the mining area and achieve environmental benefits,the unity of social and economic benefits.