Mine water treatment process mainly includes 5 parts: suspended matter removal process, iron and manganese removal process, advanced treatment process, disinfection process, concentrated water and sludge disposal process.
(1) Suspended matter removal process
Removal of suspended solids in the mine mainly adopts coagulation, sedimentation and filtration processes. Combined with engineering design experience, the design uses the process of pre-settling adjustment tank-pipe mixing-integrated water purifier-intermediate pool to complete the removal of suspended solids. The mass concentration of suspended solids in Yanzishan mine is relatively low, and the sedimentation performance of the raw water is not good. In addition, the drainage of underground water storage is generally discontinuous drainage. In order to ensure the continuity of the operation of the mine water treatment station, the entire mine water treatment system is enhanced. The adaptability of the inlet water quality, so the adjustment tank is designed as a pre-settling adjustment tank, which adopts the form of advection sedimentation tank. First-stage purification and removal of coal dust particles and suspended solids, using XCT-type full-automatic chemical pre-settler, downhole drainage is promoted by the first-stage pump, and after adding flocculant, it enters the reaction section, and the reaction section adopts unpowered hydraulic control. The CT value is maintained between 41,000 and 50,000. After the multi-stage cyclone reaction is fully mixed, the wastewater enters the sedimentation area for sedimentation and separation treatment. Its suspended solids removal rate reaches 90% to 95% or more. The clarified separation uses an inclined pipe. Increase the contact specific surface area and improve the separation effect.
(2) Iron and manganese removal process
It can be known from the water quality data that most of the iron in the mine water exists in a divalent form, and the exceeding limit of manganese is not very large. At present, the most commonly used technology for removing iron and manganese is aeration contact oxidation. Studies have shown that the catalytic effect of manganese sand filter material has a certain effect on accelerating the oxidation rate of iron and manganese. For raw water with P (iron) <5mg / L, exposure is used. The process of gas-single-stage filtration, the quality of the treated water can completely reach the standard of drinking water ((P iron) ≤ 0.3mg / L). The mass concentration of water and iron in this mine is relatively small (up to 3.5mg / L), so a single stage manganese sand filtration process using compressed air oxidation is used to remove iron and manganese from the water. Natural manganese sand with a mass fraction of manganese (calculated as Mn02) of not less than 35% is used as a filter material.
(3) Deep processing technology
The advanced treatment of mine water is mainly desalination. At present, the commonly used desalination methods are distillation, ion exchange, electrodialysis, reverse osmosis, and nanofiltration. Each method has its scope. Based on various factors, this design uses the reverse osmosis process for advanced treatment and desalination. This process can be suitable for various salinity water sources. It is more economical when the salinity is greater than 300mg / L, and the equipment is simple, the land is small, the operation is simple, and the salt is removed. The rate is high, generally 99%; but the disadvantages are that the membrane is easy to block, the cycle is short, and the water inlet pretreatment is required, and a suitable water inlet pretreatment process is required. There are two commonly used pretreatment methods: one is a traditional chemical pretreatment process; the other is a membrane pretreatment process. Microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) are commonly used. the way. Membrane pretreatment process is obviously superior to traditional treatment method in treatment effect, and has less negative impact on the environment. The nanofiltration membrane has the smallest pore size, high pollution interception rate and strong decontamination ability, but the membrane flux is small, the system's water production capacity is low, and the cost of water production is high. Compared with ultrafiltration, the membrane flux of microfiltration is not much different, but the decontamination ability is not as good as that of ultrafiltration. Therefore, this design uses the ultrafiltration method for water pretreatment, that is, the dual membrane ultrafiltration and reverse osmosis are determined as the advanced treatment process.
(4) Disinfection process
Using Cl02 as a disinfectant, it has the advantages of high efficiency, low consumption, safety, stable operation and simple management. Disinfection gas is pumped under negative pressure. The gas is sucked in by a water ejector, mixed with water, and added to a clear water tank.
(5) Disposal of concentrated water and sludge
The recovery rate of the reverse osmosis device is 70%, so 30% of the concentrated water needs to be discharged. The desalted concentrated water has a very high salt content, especially the CaSO4 content is very large. It is most suitable for extinguishing fires in Shishishan, because after the water is evaporated to dryness, a layer of CaSO4 gypsum film can be wrapped on the surface of the gangue to isolate it from the air. , To achieve the purpose of extinguishing the fire, while concentrated water can also reduce dust flying in the Shishishan.
A large amount of coal slime is settled in the pre-settling regulating tank and the automatic chemical pre-settler, which are discharged from the sludge pipe at the bottom of the tank. The main component is pulverized coal, and the mass fraction is about 1% to 2%. After the slime is processed by the sludge dewatering system, it is exported together with the mine slime, and the discharged filtrate is sent back to the pre-sinking tank for reprocessing, which achieves the purpose of "zero emissions" in the entire plant.