Ｅｘｐｅｒｉｍｅｎｔａｌ ｒｅｓｅａｒｃｈ ｏｎ ｔｒｅａｔｍｅｎｔ ｏｆ ｈｉｇｈｌｙ－ｍｉｎｅｒａｌｉｚｅｄ ｍｉｎｅ ｗａｔｅｒ ｂｙ ｖａｃｕｕｍ ｍｅｍｂｒａｎｅ ｄｉｓｔｉｌｌａｔｉｏｎ

Based on the status quo that high-salinity mine water generally exists in coal mining areas in western China, in order to realize the efficient use of mine water, the technical idea of treating highly-mineralized mine water by membrane distillation was put forward. The low-grade heat source can realize large-scale and low-cost treatment of mine water. In this study, a hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes were used to treat high-mineralized mine water by vacuum membrane distillation (VMD), which was studied on the basis of softening pretreatment with CaO and Na2CO. The effect of operating conditions such as hot liquid temperature, hot side flow rate and cold side vacuum degree on the VMD process were analyzed. The changes of the membrane performance such as membrane flux and desalination rate during the VMD concentration process were analyzed. The long-term stability of the PVDF membrane performance was investigated. The test results show that for the mine water with high hardness and low alkalinity, the lime-soda ash method can effectively remove its hardness components, and adding 600 mg/L CaO and 500 mg/L Na2CO3 can make the hardness removal rate in mine water reach more than 77%; The importance of influence on the membrane flux of VMD from strong to weak is the vacuum degree on the cold side, the temperature of the hot liquid, and the flow rate on the hot side. The optimal operating conditions in this study were temperature 75 ℃, flow rate 1L/min and vacuum degree 90 kPa, the initial membrane flux of the VMD concentration process is about 13.4 kg/(m2·h). When the concentration times were 5 and 14.5, the membrane flux drops to 81.22% and 34.51% of the initial value, respectively. Simultaneously, the desalination rate was always at 99.5% or more. With the long-term operation of VMD membrane flux gradually decreased. The elemental analysis results confirmed the existence of membrane fouling and wetting. The crystallization on inner surface of membrane filament were mainly Ca and Mg hardness, and the leakage of Na and Cl elements was an important reason for membrane wetting. The initial effect of physical cleaning and drying was better. After cleaning and drying the membrane flux returns to 93.77% of the initial value, but the recovery effect continues to decrease.