摘要
我国西部煤炭主产区气候干旱水资源短缺,煤炭开采产生的矿井水普遍具有高矿化度高硬度等特点。目前高矿化度矿井水的零排放处理普遍存在工艺流程长、系统复杂和运行成本高等问题。为了缩短处理流程提高处理效率,针对高矿化度矿井水浓缩脱盐处理过程,采用真空式膜蒸馏技术替代现有多级反渗透膜浓缩技术,对经过石灰-纯碱软化处理后的西部矿区典型煤矿高矿化度矿井水进行不同浓缩倍率处理,并针对浓缩过程中的膜污染机理和膜清洗方法进行研究。结果显示随着浓缩倍率的升高,聚偏氟乙烯(PVDF)中空纤维膜的膜通量和脱盐率逐渐降低,而产水电导率缓慢升高,当浓缩倍率达到27倍时,膜通量为8.87 L/(m^(2)·h),脱盐率为99.7%,产水电导为26.6μS/cm。膜蒸馏过程受矿井水中钙镁离子结垢导致的膜污染抑制,反冲洗和超声清洗等物理方式无法去除无机盐沉淀,连续运行96 h后PVDF膜的膜通量由12.85 L/(m^(2)·h)下降到5.21 L/(m^(2)·h)。预处理除硬工序对膜蒸馏过程钙镁结垢影响明显,当除硬率超过95%时,PVDF膜的脱盐率和膜通量衰减明显减弱。采用柠檬酸清洗剂可以有效去除钙镁沉淀引起的膜污染,在酸浓度0.87 mol/L、清洗温度38℃和清洗时间40 min的优化条件下,膜清洗效率可达到99.5%。采用原子力显微镜(AFM)和扫描电镜(SEM)对原始膜、污染膜和化学清洗后膜的微观形态和结构进行表征,结果显示清洗后膜表面沉积的污染物明显减少,但表面形态和微观结构都发生不可逆变化。
The main coal producing areas in western China have the problems of dry climate and water shortage,and the mine water produced by coal mining generally has the characteristics of high salinity and high hardness.At present,the zero-discharge treatment of high-salinity mine water generally has the problems of complex process and high operating cost.In order to shorten the treatment process and improve the treatment efficiency,in this study,the vacuum membrane distillation technology was applied to replace the existing multi-stage reverse osmosis membrane concentration technology for the high-salinity mine water concentration and desalination treatment process.The high-salinity mine water after a lime-soda softening treatment was treated with different concentration ratios, and the membrane fouling mechanism and membrane cleaning method during the concentration process were studied. The results showed that with the increase of the concentration ratio, the membrane flux and desalination rate of the polyvinylidene fluoride (PVDF) hollow fiber mem-brane gradually decreased, while the conductivity of the produced water increased slowly. When the concentration ratio was up to 27 times, the membrane flux was 8.87 L/(m^(2)·h), the salt rejection rate was 99.7%, and the water conductance was 26.6 μS/cm. The membrane distillation process was inhibited by the membrane fouling caused by the scaling of calci-um and magnesium ions in mine water, and the inorganic salt deposits could not be removed by physical methods such as backwashing and ultrasonic cleaning. After 96 hours of continuous operation, the PVDF membrane flux reduced from 12.85 L/(m^(2)·h) to 5.21 L/(m^(2)·h). The pretreatment process of hardness removal had obvious influence on the calcium and magnesium scaling in the membrane distillation process. When the hardness removal rate exceeded 95%, the desalt-ing rate and membrane flux attenuation of PVDF membrane were obviously weakened. The membrane fouling caused by the calcium and magnesium precipitation could be effectively removed by the citric acid cleaning agent. Under the optim-ized conditions of citric acid concentration of 0.87 mol/L, the cleaning temperature of 38 ℃ and the cleaning time of 40 min, the membrane cleaning efficiency could reach 99.5%. Atomic force microscopy (AFM) and scanning electron mi-croscopy (SEM) were used to characterize the microscopic morphology and structure of the original film, the contamin-ated film and the film after chemical cleaning. The results showed that the deposited pollutants on the surface of the cleaned film were significantly reduced, but the surface morphology and microscopic structure were irreversibly changed.
作者
郭强
李井峰
刘兆峰
曹志国
何瑞敏
卞伟
刘淑琴
GUO Qiang;LI Jingfeng;LIU Zhaofeng;CAO Zhiguo;HE Ruimin;BIAN Wei;LIU Shuqin(State Key Laboratory of Water Resource Protection and Utilization in Coal Mining,China Energy Investment Group,Beijing 102209,China;National Institute of Low Carbon and Clean Energy,Beijing 102209,China;China Energy Shenhua Shendong Coal Group Co.,Ltd.,Ordos 719315,China;School of Chemical&Environmental Engineering,China University of Mining&Technology−Beijing,Beijing 100083,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2023年第9期3494-3502,共9页
Journal of China Coal Society
基金
国家能源集团2030重大项目先导资助项目(GJNY2030XDXM-19-04.1)。
关键词
煤矿矿井水
水处理
膜蒸馏
膜污染
膜清洗
coal mine water
water treatment
membrane distillation
membrane fouling
membrane cleaning
