General contracting of the mine water treatment project for the construction project of the mine sewage treatment station in Shanyang Coal Mine
1. Introduction
The General contracting of the mine water treatment project for construction project of the mine sewage treatment station in Shanyang Coal Mine includes the design, procurement, construction, equipment debugging, personnel training, joint operation, environmental protection and other acceptance and all other work contents necessary for a mine sewage treatment station.
Mine sewage is composed of mine water and production wastewater. The main pollutant in mine wastewater is the suspended solids. The production wastewater comes from the wastewater of the emulsion pump station, dustfall sprinkling and grouting in the working face, which contains emulsified oil and suspended solids. Because of the unstable water inflow in the mine, and the water contains a lot of suspended solids. It is a difficult and fundamental problem for the project to achieve good treatment effect, that is, how to choose reasonable treatment unit operation and correct combination process, and realize the recovery and utilization of mine water and the water quality meeting the national discharge standard.
2. Treatment solution
After sampling mine water at different times and carrying out water quality analysis and testing, on the basis of comparing the water quality reports of analysis and testing, according to the weight of the influence of the over-standard water quality indicators (mainly TDS, SS, COD, etc.) on the process design, the influence of the most unfavorable water quality indicators is comprehensively considered as the design inlet water quality. From the analysis of mine water quality characteristics, the suspended solids in water are high, and direct reuse cannot meet the production requirements, so the focus of mine water treatment is to remove suspended solids.
For mine water treatment with high suspended solids, the traditional process is "coagulation sedimentation+filtration", which has been proved to be the most economical and practical process for mine water treatment. Therefore, the improved treatment method based on the traditional treatment process is still adopted in this project. According to the characteristics of unstable inflow of mine water and high content of the suspended solids in water, an adjustment pre-sedimentation tank is added before coagulation sedimentation. The process flow is as follows: the underground discharge flows to the regulation pre-sedimentation tank through the pipeline mixer, and coagulant is added into the pipeline mixer. Adjust a part of the effluent from the pre-sedimentation tank as yellow mud grout water, and pressurize and lift the rest by the pump. After adding coagulant (PAC basic aluminum chloride) again through the pipeline mixer, it will enter the high-density labyrinth inclined plate water purifier, and add flocculant in the mixing area for coagulation, reaction and precipitation, demulsification and oil removal to remove suspended solids (SS) and emulsified oil in the incoming water. The effluent from the water purifier enters the traveling filter, and after filtering, the suspended solids in the effluent meet the design requirements, the effluent enters the clean water tank, and is reused for water in the mine production system after disinfection. A small amount of oil-water mixture separated by the high-density labyrinth inclined plate water purifier is treated by the oil-water separator, and the effluent flows back to the discharge pool, and the oil is periodically recycled by the waste oil recycling company.
3. Construction situation
The total construction period of the general contracting of the mine water treatment project for the construction project of the mine sewage treatment station in Shanyang Coal Mine is 400 days. The scale of mine water treatment station is 1400m3/h(33600m3/d), the civil engineering part was completed at one time, and the equipment part was constructed in two phases, and the first phase of 700 m3/h can be met this time. According to the treatment design of the water treatment station, the civil pretreatment works mainly included four semi-underground reinforced concrete structure adjustment pre-settling ponds (50m×10m×4.5m) and two frame structure pump houses, which are matched with corresponding dosing rooms, power distribution rooms, pharmacy warehouses, duty rooms, etc., with a building area of 2965m2. The main body of the comprehensive water treatment workshop is a single-story portal frame light-weight building steel structure, and the ancillary buildings are two-story reinforced concrete frame structures. The eaves height of the main body is 9.4m, and the eaves height of affiliated buildings is 8.4m. The workshop mainly consists of reinforced concrete sludge thickening tank, filter press, high-density labyrinth inclined plate water purifier and other equipment foundations. The attached building on the second floor includes the underground pump house and various underground pools with a total volume of 2790m3; on the ground buildings include dosing room, distribution room, disinfection room, control room and office, etc., with a total construction area of 3234m2. Its main equipment includes: traveling-type mud scraper (oil skimmer), floating oil collector, labyrinth inclined plate water purifier, oil-water separator, traveling-type filter, concentrated integrated belt dehydrator, etc. and corresponding supporting electrical instruments.
This project is a large-scale water treatment structure group project, and the impermeability and crack prevention of hydraulic structures is a very important problem. The adjustment pre-settling tank is a semi-above-ground reinforced concrete structure, and other structures such as overflow wastewater tank, sludge tank, filtration backwashing tank and reuse tank are all underground structures, so the impermeability requirements are particularly important. In the design of this project, firstly, the water tank structure is designed for impermeability according to the specifications. In order to prevent concrete from cracking and damage under the influence of temperature and environmental humidity, expansion joints are set along the length direction of the water tank. At the same time, waterproof measures such as coating cement-based permeable crystalline coating and epoxy glass fiber reinforced plastic on the inner side of the pool wall, bottom and top, and adopting SBS waterproofing membrane on the outer side of the pool wall and bottom.
Traveling-type mud scraper (oil skimmer)Floating oil collector
Automatic dosing (PAM) system Automatic dosing (PAC)system
High density labyrinth inclined plate water purifier in water treatment workshop
Oil-water separator Sludge concentration tan
Sludge concentration and dosing system Sludge concentration and squeezing machine
4. Achieved accomplishment
In this project, the underground sewage is comprehensively treated according to the requirements of "discharging up to standard" and "production and domestic reuse". The water quality of mine water: COD ≤ 80mg/L ,SS ≤ 3000mg/L; COD 6-9mg/L SS 7-9mg/L after treatment; All indexes of water quality meet the relevant standards specified in Integrated Wastewater Discharge Standard of Yellow River Basin (Shaanxi Section), Water Quality Standard for Urban Miscellaneous Water for Urban Wastewater Recycling (GB/T18920-2002) and Code for Design of Coal Mine Industry GB50215-2005. About 70% of the effluent from water treatment stations is used as reuse water for underground fire sprinkler, ground fire water, coal washing plant water, etc. The recovery and utilization of mine water not only avoids the pollution of water source and surrounding environment caused by direct discharge, but also solves the dependence of coal mine production on external water sources, saving a large amount of water cost for coal mine production, resulting in great economic and environmental benefits.
5. FAQ
Q1. How does the project deal with the instability of mine water quantity?
A: According to the characteristics of unstable water inflow and a large amount of suspended solids in the mine, an adjustment pre-settling tank is set before coagulation and sedimentation, and the size of the adjustment tank is calculated according to the design water quantity to ensure that the water retention time is not less than 6 hours. The adjustment tank is used to balance the incoming water quality, water quantity and pre-settling, and it also reduces the load of the subsequent treatment section to ensure the stable and efficient operation of the subsequent treatment unit.
Q2. Commonly used sedimentation tanks include horizontal sedimentation tank, vertical sedimentation tank, radial sedimentation tank and labyrinth sedimentation tank. Why choose high density labyrinth inclined plate water purifier for this project?
A: Labyrinth sedimentation tank is also called winged inclined plate sedimentation tank. When water flows through winged inclined plate, it forms main flow zone (sedimentation zone), vortex zone (exchange zone) and cyclone zone (separation zone). The separation in swirl zone is not a simple gravity separation, but a separation process under the action of swirl. Another main reason of the labyrinth sedimentation tank is the existence of vortex area between the main flow area and the fins. The forced transportation and dynamic separation of vortex make the labyrinth inclined plate have high efficiency.
Q3. What is the function of labyrinth inclined plate water purifier?
A: The labyrinth inclined plate water purifier is equipped with reaction zone, oil separation zone and sedimentation zone. After coagulation, reaction, sedimentation, demulsification and oil removal, most suspended solids and oil in mine water are removed, and sludge is automatically discharged through the electric sludge discharge valve equipped with the equipment.
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