Experimental Study On The Removal Effect Of Sulfate Radical And Hardness In Mine Wastewater

Mine wastewater was produced in the coal mining process which permeating into the mine shaft. This kind of water is discharged to the grund from the mine shaft. This kind of water is discharged which is associatted with the coal and it belongs to the nature of ground water originally. But because of pulverized coal dust and rock mix and artificially pollution at the same time, it has lost its original physical properties of groundwater and it is included in the areas of sewage and waste.It had been demonstrated that adopting the assembled processes included flocculation, adsorption and Precipitation could effectively reduce sulfate radical and hardness of mine wastewater effluent, and made it reach the potable water standard.In this research, methods of single factor and perpendicularity experimental analysis were used to acertain the reaction conditions of low molecular weight inorganic flocculating agents (AlCL₃, FeCL₃), high molecular weight inorganic flocculating agents (PAC, PAF, PAFC, M180), absorbing agents (fly ash,defined diatomite) under the best disposal effect. The results of this research are as follows:(1) With the use of single factor analysis, AlCL₃ and FeCL₃ were adopted in the experiments. The best reaction conditions were ascertained that the quantities of throwing two flocculating agents were 2000 mg/L, pH values were 6 and 8, the temperature is 25℃and 30℃, quantities of throwing PAM were 5mg/L, high stirring velocity wasω₁=300r/min t₁=1min, Moderate stirring velocity wasω₂=200r/min t₂=1min, low stirring velocity wasω₃=80r/min t₃=8min, settling time was t₄=20min. The results indicated that AlCL₃ was better than FeCL₃ according to the effects. Removal rates of sulfate radical were about 90%,and removal rates of harness were about 80%. It can reach the potable water standard. But the quantities of throwing are too much, and the price is too high.(2) The best pH value, temperature and throwing quantities of PAC, PAF, PAFC and M180 were found out with the use of perpendicularity experimental design. PAC was more effective than the other three flocculating agents. The medicament combination can place to the best effect when the PAC in the dosage of 0.4g/L, the Ca(OH)₂ in the dosage of 3g/L, the PAM in the dosage of 5mg/L, as well as for increases in temperature conditions t = 20℃, pH = 8, and removal rate of sulfate radical was 87.12%; besides, removal rate of hardness was 86.63%. (3) With the use of single factor analysis, fly ash and defined were adopted in the contrastive experiments. The results indicates that the effect was not good, and it can not reach the potable water standard.(4) The dynamic testing is in the static experiment's foundation, carries on through the optimal medicament combination. We can obtain the parameter of the installment movement through the installment movement. The concrete parameter is:the water power resident time of the Adjustment sedimentation pond is 8h, the rise speed of flow in settling pond is 0.66mm/s, the rate of percolation in double-decked filtration is 5.2m/h, the filter cycle is 50h, the counter-flush time is 10min, the counter-flushing intensity is 15.98L/s·m².