Which Type of Polyacrylamide Should Be Used to Treat Coal Washing Wastewater?
Which type of polyacrylamide should be used to treat coal washing wastewater? Coal washing wastewater can be divided into two categories. One is coal washing wastewater produced when washing raw coal with better coal quality, and the other is coal washing wastewater with a shorter geological age and higher ash and impurity content. Coal washing wastewater produced during washing of raw coal. The former type of wastewater contains larger particles and lower concentration, so it is relatively easy to process. This kind of coal washing wastewater can be effectively treated using the physical method of concentration and precipitation, and the separated clean water can be reused for coal washing. The latter coal washing wastewater contains a large number of coal slime particles, which are not only small in size and high in concentration, but also have strong negative charges on the surface of the particles. It is a stable colloid system. Therefore, this kind of coal washing wastewater will not sink for a long time. It is difficult to treat. This kind of coal washing wastewater is currently generally treated by coagulation and sedimentation.
The main pollutants in coal washing wastewater are suspended solids, oily substances and organic chemicals.
1. Suspended matter
Coal washing wastewater contains a large amount of suspended solids, which is a major pollutant. This type of coal washing wastewater pollutant is composed of fine mineral particles such as kaolin and coal powder. Since the organic matter in coal is mainly black and has special discoloration, the color of the water changes and the light transmittance is poor.
2. Oil substances
The extensive use of flotation reagents such as light diesel and kerosene, as well as oil leakage and cleaning of equipment leave residues in coal. During the coal cleaning process, the coal washing water contains various amounts of oil substances.
3. Organic pharmaceuticals
Usually, during the coal washing process, coal slurry water will undergo closed-circuit circulation treatment such as filtration, dehydration, concentration and flotation. In this process, inhibitors, flocculants, foaming agents and other chemicals will be added, and during the cleaning process Remains in coal washing wastewater, causing water pollution.
Adding coagulants and flocculants to treat coal washing wastewater is a relatively common treatment method. The agents used mainly include: inorganic salt coagulants, organic polymer flocculants, and inorganic polymer flocculants. Commonly used inorganic salt coagulants mainly include aluminum salts, iron salts, etc. It is generally difficult to ensure the treatment effect of coal washing wastewater by adding inorganic salt coagulant alone. Commonly used organic polymer flocculants are mainly polymers or copolymers of polyacrylamide or its derivatives. In actual projects, inorganic salt coagulants and organic polymer flocculants are often used together, or inorganic polymer flocculants such as polyferric sulfate, polyaluminum chloride, polysilosulfate, and polyaluminum ferric chloride are used to treat coal washing wastewater. . After the combined use of polyaluminum chloride and polyacrylamide to treat coal washing wastewater, the particle aggregation effect is generally better, the sedimentation is faster, the treated water quality is clearer, and the treated circulating water can be recycled.