Discussion on the treatment and utilization of coal mine sewage

I. Introduction

As we all know, although China is a big country in the world, it has been a big land since ancient times. However, China is actually a country with very serious water shortage. How to solve this problem has become an urgent matter. To solve the shortage of water resources, the main methods are nothing more than water transfer, water storage and water saving. Obviously, water conservation is the most economical and most feasible. In terms of water saving, it mainly uses two measures of recycling and total control. With the unremitting efforts and exploration of the treatment and utilization of coal mine sewage, it has become a reality to treat and reclaim the mine water in the coal mine and the domestic sewage in the mining area. This is not only an effective measure to alleviate the shortage of water resources in coal mines, but also a good move to solve the shortage of water resources in China.

Second, the status quo of China's coal mine sewage

In the process of coal mining, due to the natural drainage of the coal-bearing aquifer caused by the water-conducting fissure generated during the mining process and the artificial drainage and drainage for ensuring safety, the water resources in the underground coal mine are jointly polluted and destroyed. . At the same time, due to the large amount of untreated coal mine water containing rock powder, coal powder and other pollutants, it also affects the environment of the mining area and its surroundings.

At present, the utilization of mine water in coal mines in China is extremely pessimistic. According to statistics, the annual discharge of mine water in China's coal mines has reached 2.2 billion tons, but the resource utilization rate of mine water is only about 20%, resulting in a large number of untreated The direct discharge of coal mine sewage not only pollutes the environment, but also wastes the mine water resources of the coal mine.

In addition, there is also a major focus on domestic sewage. Domestic sewage refers to the large amount of sewage generated by coal mine management personnel and workers in daily life. It is mainly composed of cooking, kitchen, washing clothes, bathing wastewater, and sewage after flushing the toilet. In domestic sewage, the main pollutants are organic impurities, including fat, protein and its decomposition products, carbohydrates, cellulose and soap, synthetic detergents, etc., as well as some soluble salts. Inorganic impurities such as cuttings and sand. It can be seen that the main pollution of coal mine sewage to the water environment is the odor of organic impurities in the process of degradation, the consumption of dissolved oxygen and the eutrophication.

Third, the treatment and utilization technology of coal mine sewage

1. Treatment and utilization technology of coal mine production sewage

The first step is the choice of coagulant and its mixed form. For the purification of coal mine water containing suspended solids, is generally used iron salts or aluminum salts of coagulant, of course, the most popular is the use of polymeric aluminum, there are some places use of ferric polymerization. In the process of coal mine water treatment, the mixing method of coagulant is generally mechanical mixing, pipe mixer mixing and water pump mixing. The second step is precipitation and clarification. At this time, the purification treatment of coal mine water mainly uses sedimentation tank or clarification tank as its treatment link. Sedimentation tanks generally use inclined tubes, sloping plates for precipitation and flat flow precipitation. The hydraulic cycle clarifier and the mechanically accelerated clarifier are both efficient water treatment facilities that integrate the coagulation reaction with the sedimentation process. The third step is to filter. In the processing of coal mine water, the commonly used filtration equipment includes gravity type valveless filter and quick filter. Among them, the valve and pipeline system of the quick filter are complicated, and the operation of backwashing is cumbersome: the gravity-type valveless filter can automatically perform backwashing, convenient maintenance and management, and easy operation. The filter is generally made of quartz sand and anthracite double-layer filter. The fourth step is disinfection. After the coal mine water is purified, if it is to be used as domestic water, it must be disinfected. Usually, chlorine dioxide is used for disinfection, while liquid chlorine and sodium hypochlorite are used less.

However, since coal mine underground mining machinery also needs to use engine oil and emulsified oil, oil substances will enter the mine water, and the above-mentioned coagulation, sedimentation, clarification, filtration and disinfection techniques can not effectively remove coal mine water. Among the oil pollutants. Therefore, the underground mine water should be lifted to the pre-sinking adjustment tank by the underground drainage pump, and flow into the water absorption well by the self-flowing, and then lifted into the clarification tank of the hydraulic circulation by the lift pump, and the appropriate coagulant is added before the pump, After the pump, add appropriate flocculant, effluent in the clarification tank of the hydraulic circulation and flow into the gravity-type valveless filter. Then the filter effluent will flow into the clear water pool and the chlorine dioxide will be injected before the clear water tank. Add to disinfection. The backwash water in the valveless filter flows into the collecting tank and is lifted by the submersible sewage pump into the pre-sinking regulating tank, thereby finally realizing the treatment and utilization of the coal mine water resources. As for the coal slurry water in the clarification tank of the hydraulic circulation, it is regularly discharged to the slime concentration tank, and after concentration, it is lifted into the filter press system by the slurry pump for treatment.

2. Treatment and utilization technology of coal mine domestic sewage

For the domestic sewage of coal mines, the deep process and technology combined with oxidative adsorption and enhanced clarification can be used to treat the domestic sewage in the coal mining area and then use it as circulating cooling water and boiler water for the power plant. Alternatively, the combined process and technology of adsorption and microflocculation filtration can be used to further treat the domestic sewage in the coal mining area and then use it as circulating cooling water.

In addition, because China is a water-deficient country, the rational use of coal mine sewage resources is also an important link in China's water pollution prevention and control measures. Because coal mines are mostly located in rural areas, according to their natural conditions, geographical location and the great demand for water and fertilizer in agriculture, it provides a good precondition for the use of coal mine sewage for irrigation. The irrigation water can pass through the soil and the natural purification which crop roots and microorganisms, so many contaminants can reach a very high removal rate, research shows that for P, BoD, SS, trace metals, hydroxides The removal rate of contaminants such as acid can generally exceed 95%, while for COD, potassium and nitrogen, it is about 80%. At the same time, the use of coal mine sewage for irrigation can also gradually reduce the decreasing groundwater, and can also significantly reduce the pollutant load in its receiving water. Of course, the most important thing is to make full use of the organic fertilizer in the coal mine sewage and its sufficient water, so that the crop can effectively increase production.

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