Characteristics and Difficulties of Mine Waste Water Treatment
The wastewater from this project primarily includes: natural groundwater drained from underground geological seepage into tunnels for safe production, as well as waste water containing coal dust generated during the underground coal mining process, including water sprinkling for dust suppression, fire extinguishing grouting, fire protection, and hydraulic equipment. Therefore, it possesses characteristics of groundwater but is also contaminated by human activities. The characteristics of mine wastewater depend on the geological environment of coal formation and the mineral chemical composition of the lower coal seams, with the hydrogeological conditions and water-filling factors of the mining area having a decisive impact on the quality and quantity of wastewater during the mining process. Consequently, the treatment of mine wastewater must consider the changes in water quality and quantity during the mining process.
Mine wastewater solutions and treatment process features
Based on actual field investigation and data research of the coal mine area, we have compiled test data on mine water and groundwater over the years, as well as comprehensive analysis of the local city environmental monitoring station's data. In response to this situation, our technical team has formulated a corresponding process for the coal mine area, effectively addressing the issue of daily wastewater treatment.
The mine wastewater is pumped to the grouting pond by underground drainage pumps, part of which is used for mud grouting, while the rest flows into the aeration pond by gravity. After oil removal by air flotation, it enters the inclined plate sedimentation pond for preliminary sedimentation. It is then lifted by a pump into the coagulation sedimentation equipment, where coagulant is added. After sedimentation through inclined pipes, the flocs settle to the bottom and are removed, with clear water overflowing from the top and flowing into the sand filter tank by gravity. The filtered water flows into the clear water tank by gravity, and chlorine dioxide is added at the tank to sterilize and disinfect. The backwash water from the sand filter tank flows into the sludge pond by gravity, while the supernatant flows into the aeration pond to enhance the utilization of mine wastewater resources. If the effluent is to be used for domestic purposes, the water from the sand filter tank is treated by an activated carbon adsorption unit before flowing into the clear water tank for domestic use.
Processed effect
The wastewater treatment system designed for this coal mine area produces excellent effluent quality. The main water quality indicators meet the discharge standards and can effectively adapt to fluctuating influent water quality. The effluent can reach the comprehensive sewage discharge standards, effectively addressing the issue of some indicators exceeding the standard in this type of wastewater. Based on the actual requirements and design process, a combined approach of coagulation and sedimentation with filtration is adopted to improve water quality, meet the effluent standard requirements, and ensure the long-term stable operation of the wastewater treatment system.
