Study On Reducing Coal Slime Yield By Deep Screening Of Steam Coal

China is rich in coal resource,and differences in coal quality exists among many areas.Coupling with the degree of mechanization in the process of coal mining is getting higher and higher,the content of fine size grade powder coal in raw coal alters with the change of the differences.Due to the poor quality of coal washed in the thermal coal preparation plant of Huaibei mining area,both the content and ash of powder coal are relatively high.If the screening performance of raw coal classification screen is poor,the washed clean coal products ash will not be able to meet customer requirements.Additionally,the slightly high yield of coal slurry makes economic benefits of coal preparation plant damaged.So it is necessary to choose raw coal classification equipments with better screening effect,which is the relaxation sieve,to screen deeply.This step could reduce the sieving particle size,increase the proportion of coal into the re-election,and reduce the coal yield,which makes a certain percentage of slurry products into commercial coal and thereby enhances the economic efficiency of the whole plant.In this study,based on raw coal data and equipment testing data of three thermal coal preparation plant of Huaibei Ming Area,the model of particle size distribution curve and the distribution curve model were established before and after the classification of raw coal,and sieving performance evaluation parameters were calculated out and comparatively analyzed.By analyzing design scheme of raw coal shunt classification and washing project in Zhu Xianzhuang Coal Preparation Plant,the design scheme of shunt grading with reduced slime yield was summarized on the premise of meeting customers’requirement about quality including heat and ash of washed coal.The results of studies indicates that the effect of original raw coal classification equipment screening in Zhu Xianzhuang Coal Preparation Single Plant is poor,and 0-0.5mm grain grade end coal in the sieve coarse grain products in the distribution rate is as high as 30.1%,which makes fine-grained coal not be effectively sieved resulting in high coal slime yield and low screening efficiency.After replacing Zhu Xianzhuang Coal Preparation Plant Raw Coal Classification Equipment by Relaxation Screen,the sieving particle size can be as follows to 4.5 mm and the distribution rate of 0-0.5 mm granular slurry in coarse grain products is 19.4%,which also effectively reducing the slime production,screening efficiency has also been significantly improved,the distribution rate is 10.7%lower than that before replacing.Slurry depth sieving is the key technology in the production process of thermal coal preparation plant,and relaxing sieve is the key equipment to reduce the yield of coal.And relaxing sieve has the advantages of small particle size,high screening efficiency and simple maintenance.After application of different relaxation sieve in three thermal coal preparation plant of Huaibei mining area,it was found that the KRL(V)/ED 3000x8-R45 type relaxation screen used in the Taoyuan Coal Preparation Plant has the most significant screening effect in the case of raw coal screening the most difficult circumstances.The design scheme of split into the washing is carried out in Zhu Xianzhuang Coal Preparation Plant,in which 90%of the raw coal into the relaxation sieve for 4mm grading,and sieve material and coal shunt 10%into the three products dense cyclone to sort.The program not only meets the customer’s quality requirements for commercial coal,but also has good adaptability.