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西部矿区高矿化度矿井水膜蒸馏处理技术

Technology of membrane distillation treatment for highly-mineralized mine water in western mining area

  • 摘要: 西部煤矿矿井水有相当比例为高矿化度矿井水,典型的处理工艺产品水符合再生水要求,但存在前期投资高、工艺复杂、处理成本高等问题。统计数据显示,西部7个大型煤炭基地太阳能和地热资源均属于丰富或较丰富。为实现高矿化度矿井水大规模低成本的处理,可充分利用西部太阳能、地热能和工业余热丰富的优势,采用膜蒸馏技术进行处理。其优势主要体现在:可利用低成本热源、浓缩倍数高、工艺流程短、产水水质好、膜污染(润湿)程度轻等。深入阐述了膜蒸馏与太阳能和地热能的结合工艺,指出太阳能膜蒸馏可用于反渗透浓水的地面深度浓缩;地热膜蒸馏则可直接在井下处理高矿化度矿井水,产水回用井下或地面,浓水井下封存,可大幅降低矿井水“零排放”的成本。以宁东地区100 t/h矿井水处理规模为例,分别测算了太阳能膜蒸馏所需的光热面积和地热膜蒸馏所需的换热器长度。结果显示反渗透串联膜蒸馏处理100 m3/h矿井水所需的光热面积约为8 257 m2,可充分利用处理站和蓄水池顶部空间,基本做到不新增占地。地热膜蒸馏井下直接处理100 m3/h矿井水所需的换热器长度约为9 435 m,所需的PTFE中空纤维疏水膜面积为8 333~12 500 m2,采煤工作面上覆层或下伏层的广袤岩土可满足地热膜蒸馏所需的换热空间。

     

    Abstract: A considerable proportion of mine water in western coal mines is high salinity mine water. Product water quality of typical treatment process meets the requirements of recycled water. But there are some problems with typical treatment process such as high up-front investment, complex process and high treatment cost. Statistics show that the solar energy and geothermal resources of the seven large-scale coal bases in the west are rich or relatively rich. In order to realize the large-scale and low-cost treatment of high-salinity mine water, the advantages of western solar energy, geothermal energy and industrial waste heat can be fully utilized, and membrane distillation technology can be used for treatment. Its advantages are mainly reflected in: low-cost heat source, high concentration ratio, short process flow, good water quality, and low degree of membrane fouling (wetting). The combination process of membrane distillation, solar energy and geothermal energy were described in detail, and it is pointed out that solar membrane distillation can be used for deep concentration of reverse osmosis concentrated water on the ground; eothermal membrane distillation could directly treat mine water with high salinity underground. The produced water can be reused underground or on the ground. Concentrated water can be sealed underground, resulting in significant cost reduction of “zero discharge” of mine water. Taking the 100 t/h mine water treatment in Ningdong Area as an example, the photothermal area required for solar membrane distillation and the heat exchanger length required for geothermal membrane distillation were measured. The results show that the photothermal area required for the treatment of 100 m3/h mine water by reverse osmosis series membrane distillation is about 8 257 m2, which can make full use of the space at the top of the treatment station and the reservoir, and basically do not occupy new land. Besides, the length of the heat exchanger required for direct treatment of 100 m3/h mine water under the geothermal membrane distillation is about 9 435 m. Vast rock and soil of underlying layer can meet the heat exchange space required for geothermal membrane distillation.

     

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