In the daily operation of a coal washing plant, the treatment of suspended sludge is a crucial task. Suspended sludge not only makes the coal washing water turbid and affects the coal washing efficiency, but also may cause pollution to the environment. To achieve rapid sedimentation of suspended sludge and clarity of coal washing water, the selection of appropriate sludge dewatering agents is particularly crucial. This article will provide you with a detailed introduction to the key points for selecting sludge enhancers in the treatment of suspended sludge in coal washing plants, helping you achieve the goals of rapid sedimentation and clear water.

Raw mud vs. filtered

I. Characteristics Analysis of Suspended Sludge in Coal Washing Plants

The suspended sludge in coal washing plants mainly consists of coal powder, sludge-like particles, impurities, as well as possible heavy metal ions and residues of flotation reagents. These suspended particles are fine and their surfaces are mostly negatively charged. The repulsive force between like charges keeps the particles dispersed in water, making it difficult for them to settle naturally even after standing for several months. In addition, the characteristics of sludge-water produced by different coal qualities vary significantly. The high concentration of suspended solids (SS) and chemical oxygen demand (COD) makes the conventional treatment methods inefficient.

Ii. Mechanism of Action of Sludge Efficiency Enhancers

Sludge enhancer is a kind of chemical agent specifically used to improve the dewatering performance of sludge. In the treatment of suspended sludge in coal washing plants, sludge enhancers mainly function through the following ways:

Youdaoplaceholder0 destruction of colloidal structure ‌ : Sludge enhancers can destroy the colloidal structure in suspended sludge, making it easier for coal powder particles to separate and settle.

Youdaoplaceholder0 Reduce viscosity ‌ : By reducing the viscosity of suspended sludge, sludge enhancers can make it easier for suspended sludge to remove water in equipment such as filter presses or centrifuges, and also facilitate the rapid sedimentation of particles.

Youdaoplaceholder0 Increase solid content ‌ : After using the sludge enhancer, the solid particles in the suspended sludge are more likely to aggregate together, thereby increasing the solid content, reducing the moisture content, and promoting the sedimentation of the particles.

Iii. Key Points for Selecting Sludge Enhancers

To achieve rapid sedimentation of suspended sludge in coal washing plants and clear coal washing water, the following aspects should be given particular attention when choosing sludge enhancers:

Youdaoplaceholder0 selection based on sludge properties ‌ :

The content of organic and inorganic substances in the suspended sludge of coal washing plants will affect the selection of chemicals. For suspended sludge with a high organic matter content, cationic polyacrylamide is usually more effective. Moreover, the higher the organic matter content, the higher the degree of polymerization of cationic flocculants should be selected. For suspended sludge mainly composed of inorganic substances, anionic agents can be considered.

The fineness of suspended sludge particles also affects the dosage of chemicals. The finer the particles, the greater the consumption of sludge enhancers may be.

Youdaoplaceholder0 consider the pH of the sludge ‌ :

The pH value of sludge will affect the form of hydrolysis products of sludge enhancers, and thus influence the treatment effect. For instance, the hydrolysis reaction of aluminium salts is significantly influenced by pH levels, and the optimal pH range for their coagulation reaction is 5 to 7. High-speed iron salt conditioning agents are less affected by pH levels, and the optimal pH range is 6 to 11. Therefore, when choosing a sludge enhancer, the specific pH value of the dewatered sludge should be taken into account. If the pH value deviates from the optimal range for the coagulation reaction of the agent, it is advisable to consider adjusting the pH value of the sludge or replacing the agent.

Youdaoplaceholder0 pay attention to the concentration of the reagent and the mixing effect ‌ :

The concentration of the sludge enhancer not only affects the conditioning effect, but also influences the consumption of the agent and the output rate of the sludge cake. Generally speaking, it is appropriate for the concentration of organic polymer flocculants to be between 0.05% and 0.1%. At the same time, it is necessary to ensure that the reagent is thoroughly mixed with the suspended sludge. The mixing time is generally 10 to 30 seconds, and usually no more than 2 minutes, to guarantee that the reagent can fully exert its effect.

Youdaoplaceholder0 consider the temperature factor ‌ :

The temperature of sludge directly affects the hydrolysis of sludge enhancers. In a low-temperature environment, the hydrolysis process slows down, which may affect the treatment effect. Therefore, in winter or low-temperature areas, sludge enhancers suitable for low-temperature environments should be selected or corresponding heating measures should be taken.

Iv. Conclusions and Prospects

Selecting the appropriate sludge enhancer is the key to achieving rapid sedimentation of suspended sludge in coal washing plants and clear coal washing water. By conducting a comprehensive selection based on factors such as sludge properties, pH value, reagent concentration and mixing effect, as well as temperature, the most suitable sludge enhancer for the actual situation of the coal washing plant can be found. In the future, with the continuous improvement of environmental protection requirements and the continuous progress of technology, coal washing plants should keep paying attention to the application of new products and new technologies of sludge enhancers, constantly optimize the treatment process of suspended sludge, and contribute to achieving green, low-carbon and efficient coal washing production.