Coal slime water treatment

Coal slime water is the industrial tail water produced by wet coal preparation, which contains a large number of coal slime particles and is one of the main pollution sources of coal mines. Mucus water is a complex polydisperse system. It is composed of particles of different sizes, shapes, densities and lithofacies mixed in different proportions.

source:

Coal mine slurry water can be divided into two categories: one is produced by washing raw coal with a shorter geological age and higher ash and impurity content; the other is produced during the washing process with a longer geological age and better quality coal of raw coal production.

feature:

The mineral composition of coal slime is relatively complex

The particle size and ash content of coal slime have a great influence on the flocculation and sedimentation performance

Stable in nature, difficult to handle

It involves a wide range of areas, requires a large investment, and is difficult to manage

harm:

Suspended solids in coal washing wastewater pollute the water body and affect the growth of animals and plants

Coal Washing Wastewater Residue Chemical Pollution Environment

Pollution of Residual Chemical Substances in Coal Washing Wastewater

Due to the complexity and diversity of the slime water system, the treatment methods and effects of the slime water are different. Common slime water treatment methods mainly include natural sedimentation method, gravity concentration sedimentation method and coagulation sedimentation method.

natural precipitation method

In the past, coal preparation plants mostly discharged the slime water directly into the slime sedimentation tank for natural precipitation, and the clarified water was recycled. This method does not require the addition of chemicals, reducing production costs. With the development of science and technology and the improvement of coal mining mechanization, the content of fine coal in the selected raw coal increases, which brings difficulties to the treatment of slime water. It often takes days or even months for a large number of fine particles to settle completely in the slime water. Generally speaking, coal slime water with large particle size, low concentration, and high hardness is easy to precipitate naturally, while the content of fine particles and clay minerals is large, and natural precipitation is difficult.

concentration of gravity

At present, most coal preparation plants use the gravity concentration sedimentation method to treat the slime water, and the gravity concentration sedimentation method often uses the thickener process. All the slime water enters the thickener to concentrate, the overflow is used as circulating water, and the underflow is diluted and then flotation, and the flotation tailings can be discharged outside the plant for disposal or coagulation and sedimentation treatment. Compared with natural precipitation, the gravity concentration precipitation method has a large processing capacity and high efficiency. Commonly used equipment includes thickeners, filter presses, and filters.

coagulation sedimentation method

The content of low metamorphic coal in my country is relatively high, and most of the low metamorphic coal is high muddy raw coal. The resulting coal slime has high water content and fine particles, making it difficult to settle. Coagulation is often used in coal preparation plants to treat slime water, that is, by adding chemicals to settle and separate suspended solids in the slime water in the form of larger particles or loose flocs, which is one of the main means of deep clarification of slime water. . The coagulation treatment with inorganic coagulants is called coagulation, and the coagulation treatment with polymer compounds is called flocculation. The combined use of coagulant and flocculant can improve the effect of coal slime water treatment. Commonly used agents include inorganic flocculants, polymer flocculants, and microbial flocculants.

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