In the application of mine water treatment technology, as drinking water after treatment, it must be purified and then desalinated. my country’s mine water purification treatment technology started in the late 1970s, and is currently used for purification treatment structures that treat surface rivers and lakes with a processing capacity of less than tens of thousands of tons per day. Most of them are used in coal mine water treatment processes. Past, such as pre-sedimentation tank, reaction sedimentation tank (or clarification tank), filter tank, etc. After the mine water is purified, it can be used as industrial water or domestic water. The purification treatment technologies that have been put into use mainly include: sedimentation, coagulation sedimentation, coagulation sedimentation filtration (coagulation clarification filtration) and so on. The mine water directly discharged after treatment usually adopts sedimentation or coagulation sedimentation technology. After treatment, it is usually used as process water or other water by coagulation sedimentation filtration (coagulation clarification filtration) treatment technology. After treatment, it is used as domestic water and must be disinfected after filtration. Some mine waters containing suspended solids have high salt content, and must be purified and then desalinated as drinking water after treatment.
Status of mine water treatment technology
(1) Coagulant and mixed form.
The purification treatment of mine water containing suspended solids usually uses aluminum salt or iron salt coagulant. At present, polyaluminum chloride is more commonly used, and polyaluminum iron is also useful. The flocculant mainly uses polyacrylamide. In mine water treatment, coagulant mixing methods usually adopt water pump mixing, pipeline mixer mixing and mechanical mixing. Among them, water pump mixing is more commonly used.
(2) Precipitation and clarification.
Mine water purification treatment uses sedimentation tanks or clarification tanks as the main processing unit. The sedimentation tank adopts advection sedimentation and inclined tube (plate) sedimentation, and its treatment energy consumption is small, but there are disadvantages such as large area of the treatment facility, easy clogging of sedimentation sludge and poor sludge discharge. Mechanically accelerated clarifiers and hydraulic circulation clarifiers are all water treatment facilities that integrate the coagulation reaction and precipitation process. The hydraulic circulation clarifier has low power consumption during the treatment process, strong load impact resistance, simple facility maintenance and convenient operation, etc. advantage. The mechanically accelerated clarification tank occupies a small area, but the processing energy consumption is large, and the equipment maintenance workload is large. In practical applications, the treatment effect is not as good as the hydraulic circulation clarification tank. Air flotation tanks are also used, but there are fewer applications.
Commonly used filtering facilities for mine water treatment are fast filter and gravity valveless filter. The pipeline and valve system of the fast filter is complicated, and the backwashing operation is cumbersome; the gravity-type valveless filter can automatically backwash, which is easy to operate, easy to manage and maintain. The filter usually uses a double-layer filter material of anthracite and quartz sand.
After the mine water is purified, it must be disinfected as domestic water. Generally, chlorine dioxide is used for disinfection, and sodium hypochlorite and liquid chlorine are less used.
(5).Mine water mainly contains suspended solids mainly composed of coal dust, which has the characteristics of black color, loose structure of alum blooms formed after dosing, and slow settlement speed.
Many suspended solids-containing mine water treatment projects, after being put into operation, the designed water volume and water quality did not meet the design requirements, mainly because of insufficient response, advection or large surface load of the inclined pipe sedimentation tank. On the other hand, because the lifting pump, water supply pump, dosing equipment, disinfection equipment, control system and auxiliary buildings (structures) are all designed to treat water according to the design, this causes a huge waste of project investment.
(6). The concentration of suspended solids in the mine water of different coal mines is quite different, which determines that the types and amounts of coagulants added are not the same.
Due to improper selection and dosing of coagulant, some coal mine water treatments fail to achieve the expected results. Due to the inability to monitor the incoming and outgoing water quality, treatment flow rate, dosage, and tank level in time, many mine water treatment projects only have pumps and simple chemical dosing devices. Therefore, the water volume and water quality after the mine water treatment cannot be obtained. ensure.
(7). The mining machinery used in underground coal mine production needs to use emulsified oil and motor oil. Oily substances enter the mine water. Conventional coagulation, inclined pipe precipitation and filtration technologies cannot effectively remove the oily substances in the mine water.
Features of mine water treatment technology
Determine the technical parameters of the process according to the characteristics of the water quality of the mine, and use the one-time upgrade to the hydraulic circulation clarification tank, and then flow into the subsequent treatment structures by itself. The effluent water quality is stable and reliable, with less power equipment and lower energy consumption.
It adopts the process technology that combines the hydraulic circulation clarifier and the gravity valveless filter tank. The main treatment structure adopts the reinforced concrete structure, which has a small footprint, long service life, low engineering investment, simple technology, convenient operation and management, and low operating cost Features.
The floating oil in the mine water is destabilized after being put into the electrolyte coagulant, and is effectively removed by being trapped and adsorbed by a large amount of return sludge in the hydraulic circulation clarifier.
The mine water purification and treatment system realizes the whole process monitoring of automatic dosing, automatic mud discharge, and automatic backwashing, including the electric control system, the upper monitoring system, the PLC system and the instrument detection system. The instrument detection system includes continuous automatic detection of dosing flow, processing flow, pool level and dosing tank level, and turbidity of incoming and outgoing water.
The mine water is lifted by the underground drainage pump to the pre-sedimentation tank, flows into the suction well by itself, and is lifted by the lift pump into the hydraulic circulation clarification tank. The coagulant is added before the pump and the flocculant is added after the pump. The effluent of the hydraulic circulation clarification tank flows into the gravity type by itself. There is no valve filter, the effluent from the filter flows into the clean water tank by itself, and chlorine dioxide is added before the clean water tank for sterilization and disinfection. Recoil of the valveless filter tank The water flows into the collection tank by itself, and is lifted by the submersible sewage pump into the pre-sedimentation tank to improve the utilization rate of the mine’s water resources. The slime water in the mud bucket in the hydraulic circulation clarification tank is regularly discharged to the slime thickening tank, and after concentration, it is lifted by the slurry pump into the filter press system for processing.