高盐矿井水浓缩液双极膜电渗析试验研究

Experimental study on bipolar membrane electrodialysis of high-salt mine water concentrate

基于高盐矿井水的零排放和资源化利用,采用BP-A-C-BP三隔室构型的双极膜电渗析处理高盐矿井水浓缩液。以河北某矿高盐矿井水为原水,经过预处理+RO+脱碳+浓水RO+ED浓缩,最终浓缩液TDS质量浓度达到93040 mg/L,进行双极膜电渗析试验,探究了电流密度、循环流量以及极室电解质浓度对于双极膜电渗析产酸碱效果的影响。结果表明:电流密度10~40 mA/cm^(2),随着电流密度的增大,操作电压升高,电流效率和产能逐渐减小,能耗逐渐增加,最佳电流密度为30 mA/cm^(2);循环流量10~30 L/h,随着循环流量的增大,电流效率和产能上升、能耗降低,进一步提高循环流量至40 L/h时反而增加能耗,降低产能,最佳循环流量为30 L/h;极室电解质浓度不宜过低、过高,容易增加能耗,浓度适中时的双极膜电渗析的水解离效果最好,最佳极室电解质浓度为2%。初始盐室浓缩液4 L、酸室和碱室分别为去离子水1.5 L、极室2%硫酸钠溶液2 L,电流密度为30 mA/cm^(2),极室循环流量为60 L/h,其他各室循环流量为30 L/h,运行120 min时,酸、碱浓度分别为6.91%、5.38%,达到试验预期目标,电流效率、产能及能耗分别为74.21%、1.49 kg/(m^(2)·h)、1.66 kWh/kg。经双极膜电渗析工艺产生的酸碱液可用于高盐矿井水零排放工艺以及煤炭下游产业链中,实现了浓缩液的非相变资源化,避免出现杂盐难处理的问题,同时也提高了废水的经济价值。

Based on the zero discharge and resource utilization of high-salt mine water,BP-A-C-BP three-chamber configuration bipolar membrane electrodialysis is used to treat high-salt mine water concentrate.Taking the high-salt mine water of a mine in Hebei as the raw water,after pretreatment+RO+decarburization+concentrated water RO+ED concentration,the final concentrate TDS reaches 93040 mg/L,and the bipolar membrane electrodialysis test is carried out.The effects of current density,circulating flow rate and electrolyte concentration in the polar chamber on the acid and alkali production by bipolar membrane electrodialysis are investigated.The results show that in the current density range of 10-40 mA/cm^(2),with the increase of current density,the operating voltage increases,the current efficiency and capacity decrease gradually,and the energy consumption increases gradually.The optimal current density is 30 mA/cm^(2).When the circulating flow rate is in the range of 10-30 L/h,with the increase of the circulating flow rate,the current efficiency and production capacity increase,and the energy consumption decreases.Further increasing the circulating flow rate to 40 L/h will increase the energy consumption and reduce the production capacity.The optimal circulating flow rate is 30 L/h.The electrolyte concentration in the polar chamber should not be too low or too high,which is easy to increase energy consumption.The hydrolysis effect of bipolar membrane electrodialysis is the best when the concentration is moderate,and the optimal electrolyte concentration is 2%.The initial salt chamber concentrate of 4 L,the acid chamber and the alkali chamber are respectively 1.5 L deionized water and 2 L of 2%sodium sulfate in polar chamber.The current density is 30 mA/cm^(2),the circulating flow rate in polar chamber is 60 L/h,and the circulating flow rate in other chambers is 30 L/h.After 120 min of operation,the acid and alkali concentrations are 6.91%and 5.38%,respectively,which reach the expected target of the experiment.The current efficiency,productivity and energy consumption are 74.21%,1.49 kg/(m^(2)·h)and 1.66 kWh/kg,respectively.The acid and alkali solution produced by bipolar membrane electrodialysis process can be used in the zero discharge process of high-salt mine water and the downstream industrial chain of coal to realize the non-phase change resource of concentrated liquid.It avoids the problem of miscellaneous salt difficult to deal with,and also improves the economic value of wastewater.