In recent years, China's coal washing and processing industry has made great progress with the development of the coal industry. The selection capacity of the national coal preparation plant is close to 600 million tons, and the proportion of raw coal is about 40%. At the same time, higher requirements are placed on the quality of the selected clean coal. It is hoped to produce clean coal with lower ash and moisture to meet the needs of the export and domestic markets. Reducing the moisture of coking coal is mainly to reduce the moisture of flotation clean coal, which is an urgent problem to be solved in today's coal preparation plant. In the past few years, the domestically developed pressure filter and fine coal filter press for flotation of clean coal have successfully developed satisfactory results. However, it should also be noted that these two devices still have shortcomings such as large investment, complicated system and large floor space. The sedimentation filter centrifuge is used in coal preparation plant for dehydration of coal slurry and flotation clean coal for many years. It has low product moisture, large processing capacity, small floor space, no auxiliary equipment, simple system and suitable for material concentration range. Great advantages.
I. Working principle and performance analysis of sedimentation filter centrifuge The sedimentation filter centrifuge is a continuous production of solid-liquid separation equipment. Its working principle is: when the material enters the drum of the centrifuge, under the action of centrifugal force, the material The solid particles in the sediment settle on the inner wall of the drum, and the liquid and a small amount of fine particles which are difficult to settle are discharged from the overflow port to become a centrifugal liquid. The solid particles are sent from the spiral to the filtration section. Due to a certain slip between the screw and the drum, the material is further dehydrated and the final product is discharged from the discharge port.
The main factors affecting the working effect of the sedimentation filter centrifuge are as follows: First, the centrifugal strength. That is, the ratio of the centrifugal force to the gravity of the material depends mainly on the rotational speed of the drum. The speed of the early centrifuge drum was 700-1000 r/min and the centrifugal strength was 500-700. With the continuous emergence of new materials and new technologies, the current drum speed of the centrifuge reaches 1500r/min, and its centrifugal strength can reach 1400. The rotating speed of the small centrifuge is 3000r/min, and the centrifugal strength reaches 2500 or more. Thereby greatly improving the solid-liquid separation effect and reducing the moisture of the product. The second is the structural parameters of the centrifuge. For example, the ratio of the length of the drum to the diameter, that is, the aspect ratio; the difference in rotational speed between the pusher screw and the drum; the height of the weir; the taper angle of the filter section and the size of the screw pitch, and the size of the mesh. The third is the nature of the material being separated. Mainly the particle size and viscosity of the material. As the content of fine fraction in the material increases, when the content of -0.045mm in the material exceeds 40%, the product moisture and centrate concentration increase rapidly, and the solid yield and dehydration efficiency decrease significantly. The viscosity increases and the centrifugal effect also deteriorates.
The sedimentation filter centrifuge can be applied to the recovery and dewatering of flotation clean coal and primary slime in the coal preparation plant. Under the same material conditions, the moisture content of the product is lower than that of the pressure filter, the vacuum filter and the filter press, and the relative processing capacity is large, which has satisfactory application effects.
Second, the development of sedimentation filter centrifuges in China Before the 1980s, domestic coal preparation plants only imported YIIM-1 and domestic WX-1 decanter centrifuges from the former Soviet Union, and applied to slime in some coal preparation plants. Dehydration with tail coal has achieved good results. However, due to the short life of components and the large amount of maintenance and repair work, it has not been well applied.
In order to solve the problem of high moisture in flotation clean coal, in the early 1980s, China began to study the sedimentation filter centrifuge. The first WLG900 prototype was put into use in Lingshan Coal Preparation Plant in 1983 and passed the technical appraisal. In the future, more than 20 sets were promoted and applied in the national coal preparation plant. However, due to some structural problems, the precision of machining is not enough, resulting in short use time of the differential, fast wear of the spiral and screen, and difficulty in overhaul. As a result, the centrifuge failed to be further promoted and applied. For the problems of this model, since 1986, China has developed the WLG-1100×2600 centrifuge. The machine is used for dewatering of flotation clean coal in Zhuzhou Coal Preparation Plant. When the average concentration of feed is 21%, the average ash content of the feed is 7.76%, and the average of -0.045mm grain material in the feed is 42.8%, the treatment is carried out. The capacity is 21.16t / h, the product ash is 7.12%, the moisture is 22.12%, 2 percentage points lower than the 58m2 disk vacuum filter, and the production capacity is 2.7 times higher. Although the machine works well, it has not been promoted due to the influence of the WLG900 model.
In the early 1980s, in order to improve the level of coal preparation machinery in China, the introduction of equipment, while introducing some of the equipment manufacturing technology, sedimentation filter centrifuge is one of them. China has introduced the drawings and technology of American BIRD company. The model of the product is TCL type sedimentation filter centrifuge, and it is applied in some coal preparation plants, but the quantity used is not much.
The Malan Coal Preparation Plant and the Slope Coal Preparation Plant in our province used dewatering by sedimentation centrifuges, which all received good dewatering effect and greatly improved the treatment capacity.
The sedimentation filter centrifuge has obvious advantages in the dewatering of coal slime and flotation clean coal. However, in recent years, it has not been widely promoted and applied. The reasons for analysis are as follows:
*, the WLG centrifuge designed and researched by our country has some problems in production and application due to the limitations of the technical level, materials and manufacturing processes at that time. The structural parameters of the centrifuge, the service life of the components, the processing capacity and the process parameters in use are all different from those of similar centrifuges in foreign countries.
Second, in terms of manufacturing precision, processing technology and materials, the design requirements are not met, and the manufacturing quality cannot be guaranteed, thus affecting the normal use and life of the centrifuge.
Third, research and manufacturing units can not continuously improve and improve the structure of products according to the problems that arise and the requirements of users, and improve the quality of products; some manufacturers can not keep up with the after-sales service, and problems can not be solved quickly, affecting The use of centrifuges.
III. Development Suggestions In order to promote the application of efficient slime dewatering equipment in coal preparation plants, it is recommended to do the following work:
1. On the basis of fully investigating the current situation of sedimentation filter centrifuges at home and abroad, fully affirm the advantages of previous models, analyze their shortcomings, find out the reasons, and optimize the main structural parameters of domestic centrifuges.
2. Strengthen the preliminary experimental research work of the centrifuge. In the conditional development unit, the on-site coal sample should be applied and sufficient tests should be carried out to further optimize the relevant structural parameters of the centrifuge.
3. In the process of research and determination of the program, it should be based on the reliable operation of the equipment, and the technological advancement is the premise. It is necessary to strengthen the combination of research, design, factory and coal preparation plant, fully listen to opinions from various parties, and organize experts to demonstrate to ensure the reliability and feasibility of the program.
4. The manufacturer shall improve the level of machining technology, ensure the manufacturing precision of the centrifuge, ensure the quality of the centrifuge, and technically reach the international advanced level.
5. The coal preparation plant that conducts industrial tests shall evaluate the main parameters of the centrifuge and conduct research on related processes to further reduce the concentration of the centrifugal liquid and product moisture, and improve the maintenance and repair level.
In short, the sedimentation filter centrifuge is an efficient dewatering equipment, which has a good prospect of popularization and application in the coal preparation plant. It is necessary to speed up the development of research and development, to reduce the slime of the coal preparation plant, reduce the moisture of the selected coal, and provide new and efficient equipment.
I. Working principle and performance analysis of sedimentation filter centrifuge The sedimentation filter centrifuge is a continuous production of solid-liquid separation equipment. Its working principle is: when the material enters the drum of the centrifuge, under the action of centrifugal force, the material The solid particles in the sediment settle on the inner wall of the drum, and the liquid and a small amount of fine particles which are difficult to settle are discharged from the overflow port to become a centrifugal liquid. The solid particles are sent from the spiral to the filtration section. Due to a certain slip between the screw and the drum, the material is further dehydrated and the final product is discharged from the discharge port.
The main factors affecting the working effect of the sedimentation filter centrifuge are as follows: First, the centrifugal strength. That is, the ratio of the centrifugal force to the gravity of the material depends mainly on the rotational speed of the drum. The speed of the early centrifuge drum was 700-1000 r/min and the centrifugal strength was 500-700. With the continuous emergence of new materials and new technologies, the current drum speed of the centrifuge reaches 1500r/min, and its centrifugal strength can reach 1400. The rotating speed of the small centrifuge is 3000r/min, and the centrifugal strength reaches 2500 or more. Thereby greatly improving the solid-liquid separation effect and reducing the moisture of the product. The second is the structural parameters of the centrifuge. For example, the ratio of the length of the drum to the diameter, that is, the aspect ratio; the difference in rotational speed between the pusher screw and the drum; the height of the weir; the taper angle of the filter section and the size of the screw pitch, and the size of the mesh. The third is the nature of the material being separated. Mainly the particle size and viscosity of the material. As the content of fine fraction in the material increases, when the content of -0.045mm in the material exceeds 40%, the product moisture and centrate concentration increase rapidly, and the solid yield and dehydration efficiency decrease significantly. The viscosity increases and the centrifugal effect also deteriorates.
The sedimentation filter centrifuge can be applied to the recovery and dewatering of flotation clean coal and primary slime in the coal preparation plant. Under the same material conditions, the moisture content of the product is lower than that of the pressure filter, the vacuum filter and the filter press, and the relative processing capacity is large, which has satisfactory application effects.
Second, the development of sedimentation filter centrifuges in China Before the 1980s, domestic coal preparation plants only imported YIIM-1 and domestic WX-1 decanter centrifuges from the former Soviet Union, and applied to slime in some coal preparation plants. Dehydration with tail coal has achieved good results. However, due to the short life of components and the large amount of maintenance and repair work, it has not been well applied.
In order to solve the problem of high moisture in flotation clean coal, in the early 1980s, China began to study the sedimentation filter centrifuge. The first WLG900 prototype was put into use in Lingshan Coal Preparation Plant in 1983 and passed the technical appraisal. In the future, more than 20 sets were promoted and applied in the national coal preparation plant. However, due to some structural problems, the precision of machining is not enough, resulting in short use time of the differential, fast wear of the spiral and screen, and difficulty in overhaul. As a result, the centrifuge failed to be further promoted and applied. For the problems of this model, since 1986, China has developed the WLG-1100×2600 centrifuge. The machine is used for dewatering of flotation clean coal in Zhuzhou Coal Preparation Plant. When the average concentration of feed is 21%, the average ash content of the feed is 7.76%, and the average of -0.045mm grain material in the feed is 42.8%, the treatment is carried out. The capacity is 21.16t / h, the product ash is 7.12%, the moisture is 22.12%, 2 percentage points lower than the 58m2 disk vacuum filter, and the production capacity is 2.7 times higher. Although the machine works well, it has not been promoted due to the influence of the WLG900 model.
In the early 1980s, in order to improve the level of coal preparation machinery in China, the introduction of equipment, while introducing some of the equipment manufacturing technology, sedimentation filter centrifuge is one of them. China has introduced the drawings and technology of American BIRD company. The model of the product is TCL type sedimentation filter centrifuge, and it is applied in some coal preparation plants, but the quantity used is not much.
The Malan Coal Preparation Plant and the Slope Coal Preparation Plant in our province used dewatering by sedimentation centrifuges, which all received good dewatering effect and greatly improved the treatment capacity.
The sedimentation filter centrifuge has obvious advantages in the dewatering of coal slime and flotation clean coal. However, in recent years, it has not been widely promoted and applied. The reasons for analysis are as follows:
*, the WLG centrifuge designed and researched by our country has some problems in production and application due to the limitations of the technical level, materials and manufacturing processes at that time. The structural parameters of the centrifuge, the service life of the components, the processing capacity and the process parameters in use are all different from those of similar centrifuges in foreign countries.
Second, in terms of manufacturing precision, processing technology and materials, the design requirements are not met, and the manufacturing quality cannot be guaranteed, thus affecting the normal use and life of the centrifuge.
Third, research and manufacturing units can not continuously improve and improve the structure of products according to the problems that arise and the requirements of users, and improve the quality of products; some manufacturers can not keep up with the after-sales service, and problems can not be solved quickly, affecting The use of centrifuges.
III. Development Suggestions In order to promote the application of efficient slime dewatering equipment in coal preparation plants, it is recommended to do the following work:
1. On the basis of fully investigating the current situation of sedimentation filter centrifuges at home and abroad, fully affirm the advantages of previous models, analyze their shortcomings, find out the reasons, and optimize the main structural parameters of domestic centrifuges.
2. Strengthen the preliminary experimental research work of the centrifuge. In the conditional development unit, the on-site coal sample should be applied and sufficient tests should be carried out to further optimize the relevant structural parameters of the centrifuge.
3. In the process of research and determination of the program, it should be based on the reliable operation of the equipment, and the technological advancement is the premise. It is necessary to strengthen the combination of research, design, factory and coal preparation plant, fully listen to opinions from various parties, and organize experts to demonstrate to ensure the reliability and feasibility of the program.
4. The manufacturer shall improve the level of machining technology, ensure the manufacturing precision of the centrifuge, ensure the quality of the centrifuge, and technically reach the international advanced level.
5. The coal preparation plant that conducts industrial tests shall evaluate the main parameters of the centrifuge and conduct research on related processes to further reduce the concentration of the centrifugal liquid and product moisture, and improve the maintenance and repair level.
In short, the sedimentation filter centrifuge is an efficient dewatering equipment, which has a good prospect of popularization and application in the coal preparation plant. It is necessary to speed up the development of research and development, to reduce the slime of the coal preparation plant, reduce the moisture of the selected coal, and provide new and efficient equipment.
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