Coal is still the main body of energy in China. Although coal mine water is defined as industrial sewage, its essence is groundwater and belongs to an unconventional water resource. Du Song, director of the Institute of Geological Storage Technology of the General Institute of Survey and Research of the China Coal Geology Administration, interpreted it as a participant in the "Guiding Opinions on Strengthening the Protection and Utilization of Mine Water".

Coal is still the main body of energy in China. Although coal mine water is defined as industrial sewage, it is essentially groundwater and belongs to unconventional water resources. According to statistics, the total water inflow from China's coal mines is about 8 billion cubic meters per year, which is equivalent to the total water transfer capacity of the first phase of China's South-to-North Water transfer Project. In recent years, the protection and utilization capacity of mine water in China has been continuously improved, and the utilization has continued to increase, but it is still faced with some problems, such as uneven regional development, unclear statistical base, imperfect policy standards, incomplete technical equipment, inadequate protection and utilization, and so on. In order to further promote the protection and utilization of mine water, alleviate the shortage of water resources, protect the ecological environment, and support the high-quality development of energy and resources industry The National Development and Reform Commission, the Ministry of Water Resources, the Ministry of Natural Resources, the Ministry of Ecological Environment, the Ministry of Emergency Management, the General Administration of Market Supervision, the State Energy Administration and the State Administration of Mine Safety jointly formulated and issued the guidance on strengthening the Protection and Utilization of Mine Water (Development and Reform (2024) No. 226) (hereinafter referred to as the guidance). The guiding opinions are mainly aimed at the protection and utilization of coal mine water and non-coal mine water.

In fact, on October 20, 2023, the General Office of the National Development and Reform Commission issued the "Guiding Opinions on Strengthening the Protection and Utilization of Mine Water (Draft for Comments)"(hereinafter referred to as the "Draft for Comments"), and solicit opinions from the Ministry of Science and Technology, the Ministry of Industry and Information Technology, the Ministry of Justice, the Ministry of Natural Resources, the Ministry of Ecology and Environment, the Ministry of Housing and Urban-Rural Development, the Ministry of Water Resources, the Ministry of Agriculture and Rural Affairs, the Ministry of Emergency Management, the State Administration of Taxation, the General Office (Office) of the National Forestry and Grassland Administration, the Development and Reform Commission of relevant provinces (autonomous regions, municipalities), and large coal enterprises and industry associations.

The author participated in the proposal of the "Draft for Comments" and compared it with the "Guiding Opinions" officially issued this time to gain some new understanding and share it with the industry.

From the perspective of overall requirements, it is emphasized that "key core technology equipment and industrial application levels have been significantly improved." In the "Guiding Opinions","taking improving the level of technical equipment as the starting point" was changed to "taking technological innovation" as the driving force, and the "basic principles" part was deleted from the official document because the expression "source reduction, limited water conservation, unified allocation, and scientific and technological support" in the basic principles part of the "Draft for Comments" has been reflected in the guiding ideology. The "Draft for Comments" proposes a requirement to increase the overall utilization rate of mine water to 60%, but it is not mentioned in the official document. It only mentions that the utilization rate of mine water in the Yellow River Basin will be increased to 68%. This is consistent with China's basic national conditions of the dominant position of coal production capacity in the Yellow River Basin, and also reflects China's emphasis on the ecological environment of the Yellow River Basin.

In the second part,"Strengthening the Protection of Mine Water Sources", the "Draft for Comments" specifically emphasizes the role of "planning environmental assessment" in controlling the source of mine water management, but it is deleted from the "Guiding Opinions" and more emphasis is placed on Specific working methods and means. In addition, the "Implementation of safety supervision" has been added to the "Guidance Opinions". Strengthen the supervision measures of 'one mine, one policy' for coal mine water, carry out special inspections for water damage prevention and control, and focus on inspecting the construction of mine water inflow monitoring facilities, drainage facilities, waterproof and sealing facilities, etc. Strengthen the construction of coal mine emergency response capabilities, establish a coal mine safety Incident Response Service mechanism, build a coal mine safety production risk monitoring and early warning platform, and organize regular emergency drills." This shows that the national level attaches great importance to safety supervision and emphasizes the guarantee role of emergency measures.

In the third part, "promoting the quality and classification treatment of mine water", "draft for soliciting opinions" and "guidance" are three specific contents, which give guidance and suggestions from three aspects: suspended solids, salinity (salinity), acidity and other special pollutants. The "downhole hierarchical treatment and quality utilization" is clearly encouraged in the "guidance", and the supermagnetic separation technology recommended in the "draft for soliciting opinions" is not reflected in the official draft. The suggestions for improving the intelligent control system in the "draft for soliciting opinions" are reflected in the "guidance", which shows that the downhole intelligent control is an inevitable development trend; at the same time, the requirements for emergency plans have been added to the "guidance". "desalination" is the key link to realize zero discharge of mine water, but the energy consumption of thermal evaporation technology is too high. A new term "green desalination" is put forward in both "draft for soliciting opinions" and "guidance". That is, the use of renewable energy combined with low energy consumption technology to achieve the separation of salt and water; in the guidance, it is proposed to "encourage the exploration of natural restoration" for the closure of mining areas and closed mines. Evaporation ponds are recommended in the guidelines for the disposal of high salt water.

In the fourth part of the "Promoting the Comprehensive Utilization of Mine Water" section, the four articles in the "Draft for Comments" were revised to three articles in the "Guiding Opinions". The "exploration and implementation of the mine water quota system" proposed in the "Draft for Comments" has been deleted. The author believes that the current concept of "quota system" is still vague and involves various policy support, which needs to be studied in depth. The "Guiding Opinions" adopt "scientific allocation of water" and put forward suggestions to "support the construction of large-scale mine water treatment facilities and supporting pipe network projects such as centralized water supply pipe networks, joint debugging and joint supply pipe networks"; the "Draft for Comments" and the "Guiding Opinions" both propose "strict water intake permits", especially in special areas, requiring priority to use mine water resources. The technologies of "ectopic recharge or storage of mine water" and "deep geological storage of high salt water" proposed in the "Draft for Comments" are not mentioned in the "Guiding Opinions", which shows that the reliability of such technologies is not yet fully recognized at the national level., research and demonstration needs to be continued.

The four opinions in the "Implementation of Key Projects for Mine Water Protection and Utilization" in the "Draft for Comments" are "Key Projects for Co-mining of Coal and Water","Key Projects for Underground Mine Water Treatment and Utilization","Key Projects for Mine Water (Near) Zero Emission","Key Projects for Mine Water Supporting Pipe Network" were deleted from the "Guiding Opinions".

In the section "Improving the Mine Water Utilization System and Mechanism", all five suggestions mentioned in the "Draft for Comments" were adopted. Among the suggestions on "improving the statistical measurement assessment system", the "Guiding Opinions" emphasize the importance of mine water statistics, measurement and monitoring, and suggest improving the data system and statistical mechanism to build a "mine water big data" system. Regarding "improving policy standards," the "Guiding Opinions" are almost consistent with the "Draft for Comments". In the "Guiding Opinions", emphasis has been added to the local standards of "nine provinces (regions) in the Yellow River Basin and the base regions of the Xinjiang Uygur Autonomous Region."

With regard to the suggestion of "perfecting the price and tax mechanism", the expressions of "opening up the government pricing of mine water" and "encouraging the use of government purchase services or subsidies" in the "draft for soliciting opinions" were deleted in the "guidance". Encourage both supply and demand to negotiate pricing independently At the same time, the suggestion of "steadily promoting the reform of water resources tax, no additional levy of water resources tax on mine water supplied to downstream users, and simplifying the examination and approval process of mine water access permission for downstream users" was not adopted in the "guiding opinions". However, it has adopted the suggestion of "implementing the preferential tax policies such as value-added tax on the use of reclaimed water from mine water production by enterprises in accordance with the current regulations". The proposal of "sound and standardized third-party governance market" mentioned in the draft for soliciting opinions has been deleted, but the guiding opinion has adopted the suggestion of "exploring the mode of eco-environment-oriented development (EOD)", which is in line with the new trend of ecological environment construction in China. Among the suggestions of strengthening scientific and technological support, the guiding opinions have adopted almost all the contents of the draft for soliciting opinions, especially the proposal of "supporting the construction of scientific and technological innovation bases related to the protection and utilization of mine water". The author believes that it will become a new direction for the construction of mine water scientific research team and platform.

Through comparative analysis of the Guiding Opinions, the author focuses on analyzing the following issues:

(1) Is it difficult to achieve a "68%" utilization rate?

The "Guiding Opinions" propose that "by 2025, the utilization of mine water across the country will continue to increase and the utilization rate will continue to increase. Among them, the Yellow River Basin will strive to reach more than 68%, and the policy system and market mechanism for mine water protection and utilization will be basically established." The 68% utilization rate indicator is consistent with the "Implementation Plan for the Conservation and Intensive Utilization of Water Resources in the Yellow River Basin" jointly issued by the National Development and Reform Commission, the Ministry of Water Resources and other five ministries and commissions in 2022, which clearly states that "promoting energy sources such as eastern Gansu, eastern Ningxia, western Mongolia, northern Shaanxi, and western Shanxi. The goal of comprehensive utilization of coal mine water in the Yellow River Basin will reach more than 68% by 2025." The utilization rates of mine water in coal production bases in China's Yellow River Basin vary greatly. Although most Kuangqu mining areas have long proposed the goal of utilizing 80% to 85% mine water, they have rarely been achieved so far.

The central environmental protection inspector found that the comprehensive utilization rate of mine water in Ningdong Base in 2020 was only 26%, and in 2021 it was 37%, far lower than the "Ningdong Energy and Chemical Industry Base 2015 - 2022 Environmental Protection Action Plan" proposed by 2020 The mine water reuse rate reaches the target requirement of more than 85%. However, there are also reports that the mine water utilization rate of Shendong Coal Base has reached more than 90%.

Gu Dazhao, an academician of the Chinese Academy of Engineering, believes that the current average utilization rate of mine water in China's coal mines is about 35%. Overall, the utilization rate of water-deficient Kuangqu is higher than that of mining areas without water shortage. The utilization rate of mining areas with good mine water quality is higher than that of mining areas with poor water quality. The utilization rate of supporting industries near mining areas with high density is higher than that of supporting industries in mining areas. If the degree is low, the utilization rate of large state-owned coal mines is higher than that of local small and medium-sized coal mines. Based on this, the author believes that it is difficult to achieve the overall mine water utilization rate of 68% in the Yellow River Basin.

(2) How to deal with mine water?

China's mine water treatment technology has reached the international leading level. The suggestions of "large-scale intelligent treatment","hierarchical green treatment" and "efficient and directional treatment" put forward in the "Guiding Opinions" are higher requirements for mine water treatment. This is consistent with the goal of China's coal industry to vigorously promote the construction of smart mines and green mines in recent years. The author believes that on the basis of overall water resource allocation and coal mine water big data construction, hierarchical treatment and differentiated utilization will be achieved. Eliminating substandard treatment while avoiding excessive treatment is an inevitable trend in mine water treatment and resource utilization in the future.

(3)"Unblocking" the evaporation pond

On May 27, 2015, the former Ministry of Environmental Protection issued the "Guiding Opinions on Strengthening Environmental Protection in Industrial Parks", which clearly stated that:"All types of parks are not allowed to replace standardized sewage treatment facilities with drying ponds, evaporation ponds, etc., and existing drying ponds, evaporation ponds, etc. that do not meet relevant environmental protection requirements should be cleaned up and rectified immediately." This "Guiding Opinions" clearly state that "The treated high-salt wastewater should be disposed of in strict standards, and ground evaporation ponds can be built and operated for disposal in accordance with relevant regulations to avoid environmental pollution risks." This means that the ban on evaporation ponds for nearly 10 years has been lifted. Therefore, the author believes that the disposal ideas for high salt water in coal mines will change.

(4) Resource allocation

The author believes that the key problem in improving mine water utilization is not technical, but resource allocation. China's current water treatment equipment and technical level are sufficient to ensure mine water treatment to industrial reuse, surface Class III water and even drinking water standards. However, the key problem is that the coal mine itself cannot use up so much water resources. If the remaining water is sold to enterprises that need water, it involves a series of issues that exceed the coordination capabilities of coal mining companies, such as license approvals, resource taxes, and pipe network infrastructure. All contents in the "Improving the Mine Water Utilization System and Mechanism" section of the "Guiding Opinions", including "assessment and measurement","policy standards", and "price and tax mechanism", are all aimed at ensuring the optimization of the allocation of mine water resources. It can be seen that the country will Vigorously promote the allocation and utilization of mine water resources, including policies and infrastructure.

(5) Big data on mine water resources

The reconfiguration of unconventional water resources is inseparable from the support of big data platforms. The "Guiding Opinions" emphasize the importance of mine water statistics, measurement and monitoring. The author believes that the application of "big data" will better solve the problems of mine water treatment and resource utilization.