Mine wastewater refers to all the water infiltrated into the underground excavation space in the process of coal mining, sometimes including a small amount of surface water infiltrated.

Mine wastewater discharge is one of the pollution sources with industrial characteristics in coal industry.It is large in size and wide in range.The annual inflow of mine wastewater in China's coal development exceeds 2 billion cubic meters.Its characteristics depend on the geological environment of the coal seam and the mineral chemical composition in the coal seam.When mine waste water flows through the coal face and roadway, due to the influence of human activities, pulverized coal and some organic matter enter the water.The mine wastewater in our country usually contains suspended solids which are mainly composed of coal powder and soluble inorganic salts.Contaminants are few and often contain no toxic substances.Therefore, the purification and utilization of mine wastewater will produce huge economic and social benefits.The treatment of coal mine water depends on its quality.

Coal mine water treatment technology mainly includes: acid water neutralization, flocculation treatment to remove suspended particles, reverse osmosis removal of soluble salt and other technical combination.Adopts a variety of methods to remove or reduce the harmful substances in the mine wastewater, so that it can meet the discharge standards and the environmental quality standards of the receiving water body, or according to various needs to treat the target water quality.

Different types of mine wastewater treatment methods are:

(1) clean mine waste water.Can set up special water pipeline use, and need to carry on the disinfection treatment of drinking water.

(2) General mine water.The sedimentation method is used to remove suspended solids from the ground or above.One is to use an underground collecting tank, which is divided into sections, and a flocculant is added before the mine waste water enters the collecting tank.It will settle and overflow in each part of the catchment tank and eventually meet discharge standards.The other is to build a sedimentation tank on the ground, mine waste water after sedimentation into the sedimentation tank.When this type of water is used for domestic use and production, conventional purification processes are usually used.

When the mine wastewater treatment capacity is small, can also use the combined water purifier.It is a device that integrates condensation, precipitation, filtration and other processes in one.It has the characteristics of saving one-time investment, small footprint and convenient operation.

(3) Mine wastewater with high salinity.The commonly used treatment methods mainly include distillation, electrodialysis and reverse osmosis.Most of the electrodialysis method is used in our country, and the electrodialysis device must undergo strict pretreatment.The turbidity of the water entering the electrodialysis device is controlled below 3°, and Fe, Mn, Cl and so on meet the specified requirements.Electrodialysis uses more electricity and costs more to process.

(4) acidic mineral water.The neutralization method is used, using lime or limestone as the neutralizer.There are usually three processes: direct lime addition, limestone neutralization drum and open flow variable filtration rate expansion neutralization.The method of adding lime directly: make lime into lime milk, put it into the reaction tank, and then flow into the reaction tank.The Fe2 in the water must be inflated and oxidized.After settling in a sedimentation tank, the neutralized products Ca-SO4 and Fe (OH) 3 were removed.