Introduction

Coal washing wastewater and slime wastewater is a multi-system composed of primary slime, secondary slime and water, which contains a large amount of suspended solids, slime and mud sand, so it is also…

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Coal washing wastewater and slime wastewater is a multi-system composed of primary slime, secondary slime and water, which contains a large amount of suspended solids, slime and mud sand, so it is also called slime water.This type of wastewater contains slime particles, minerals, clay particles, etc. It has the characteristics of high concentration of SS, CODcr and BOD5. Some untreated coal slime water can have a suspended solids concentration of more than 8000mg/L.

Main pollutants of coal washing wastewater: Coal wastewater contains a large amount of suspended solids, which is a major pollutant. This kind of coal washing wastewater pollutant is composed of fine mineral particles such as kaolin and coal powder.Because the organic matter in coal is mainly black and has special discoloration, the color of water quality changes and the light transmittance is poor. The large use of flotation reagents such as light diesel oil and kerosene, as well as equipment oil leakage and cleaning, remain in the coal, and in the coal cleaning process, the coal washing water contains various amounts of oily substances.Usually in the process of coal washing, it will go through closed-circuit circulation treatment of coal slime water such as filtration, dehydration, concentration and flotation. wastewater, causing water pollution.

Coal washing plant polyacrylamide is the most widely used in coal washing wastewater treatment process.In the specific treatment process, different flocculants should be used for different properties of coal washing wastewater.Coal washing flocculant has a good treatment effect in the treatment of coal washing wastewater, and the SS removal rate is high. Compared with the gravity concentration and sedimentation method, it can effectively ensure the closed-circuit circulation of washing water, and even if the waste water is discharged out, it can basically meet the discharge standard, which has many advantages.However, the amount of flocculant used in the general coagulation and sedimentation method is relatively large, so it is recommended to use coal washing wastewater to treat the flocculant product, which has fast sedimentation speed and tight flocculation.

Process flow: The coal mined in coal mining usually contains all impurities, and the separation efficiency of coal and impurities can be increased by adding a flotation agent. Clean coal flotation, tailings sedimentation.The clean coal in the tailings is then recovered by settling, filtration or centrifugation.Polyacrylamide PAM is used in the sedimentation process, thereby promoting solid-liquid separation. Then it is sent to the concentrator, and the clean water is recovered and recycled by the overflow of the concentrator.Powdered clean coal is recovered by filtration and centrifugation.Polyacrylamide was added again during filtration and centrifugation to increase separation efficiency.