内蒙古西部干旱地区煤矿反渗透浓盐水的综合利用

Comprehensive utilization of reverse osmosis concentrated brine in coal mines in the arid areas of Western Inner Mongolia

  • 摘要: 内蒙古西部地区气候干旱,煤炭资源丰富,但矿区地下水和矿井水的矿化度普遍偏高,淡水资源严重短缺。矿区水处理厂利用反渗透技术处理大量的高矿化矿井水,尽管该技术能够解决矿区生活用水的问题和提高矿井水综合利用水平,但是反渗透设备持续产生的浓盐水引发了存放和综合利用的新问题。介绍了反渗透浓盐水的各种处理技术及其优缺点,包括排放入海、蒸发池浓缩、零排放技术、离子提取技术等。以内蒙古西部干旱区上海庙矿区的反渗透浓盐水为例,基于矿区浓盐水水质和水量特征、矿区自然条件和太阳池原理,综合评估了浓盐水离子的回收利用可行性和太阳池的应用前景。研究结果表明:矿区反渗透浓盐水中Na+、K+和Mg2+含量与海水和盐湖中对应离子质量浓度低1~2个数量级,提取钠盐、钾盐、氧化镁技术成熟,但经济可行性较低;反渗透浓盐水中Li离子质量浓度尽管高于海水和浓海水,但与工业提取的最低质量浓度(30 mg/L)和盐湖中锂的质量浓度相差30多倍,浓盐水中锂的回收利用需要未来提取技术的提升;矿区浓盐水中铀的质量浓度同样高于海水和浓海水,但与盐湖中铀的质量浓度相差1个数量级。矿区所在的内蒙古西部属于“太阳能资源丰富带”,年总太阳辐射大于6 300 MJ/m2,具有建造太阳池的先天优势,反渗透浓盐水也为太阳池提供足够的盐资源,利用反渗透浓盐水建造太阳池能提供非常可观的热能,经济可行性高。

     

    Abstract: The western region of Inner Mongolia has an arid climate and abundant coal resources, but the high degree of mineralization of groundwater and mine water in mining areas leads to a severe shortage of freshwater resources. Reverse osmosis technology is utilized by some sewage treatment plants in the mining areas to treat considerable highly mineralized mine water. This technology solves the problem of domestic water shortage in the mining areas and improves the comprehensive utilization of mine water, whereas, it raises a new issue about the storage and comprehensive utilization of the concentrated brine continuously produced by reverse osmosis plants. Various treatment technologies for reverse osmosis concentrated brine and their advantages and disadvantages are discussed, including discharge into the sea, evaporation pond concentration, zero discharge technology, and ion extraction technology. Taking the reverse osmosis concentrated brine from the Shanghai Miao mine in the western arid region of Inner Mongolia as an example, based on the water quality and quantity characteristics of the concentrated brine, the natural conditions and the principle of solar ponds in the mine, the study provides a comprehensive assessment of the feasibility of recycling concentrated brine ions and the prospects for the application of solar ponds. The results has shown that the Na+, K+ and Mg2+ ions in mine reverse concentrated brine are 1−2 orders of magnitude lower than that in salt lake and seawater. The extraction of sodium salt, potassium salt, and magnesium oxide is technically mature, but economically unfeasible. Although the Li+ ion content in reverse osmosis concentrated brine is higher than that in seawater and seawater concentrate, it is 30 times lower than the lowest industrial extraction concentration (30 mg/L) and lithium concentration in the salt lake. The technology of recycling and extracting lithium in concentrated brine needs to be improved in the near future. The uranium content in the concentrated brine of the mining area is also higher than that of seawater and seawater concentrate, but it is one order of magnitude lower than that of the salt lake. The western part of Inner Mongolia, where the mining area is located, belonging to the“abundant solar resource area”, with a total annual solar radiation above 6 300 MJ/m2, has the inherent advantage of building solar power plants. In the meantime, reverse osmosis concentrated brine provides a sufficient source of salt for the solar pond. The utilization of reverse osmosis concentrated brine for solar pond construction can provide very substantial thermal energy and is very economically viable.

     

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