Study On Preparation Technology And Chemical Mechanism Of Ultra-pure Coal Prepared By Haishiwan Coal

Haishiwan coal is a low metamorphic weak coal,which has the characteristics of extra low internal ash,extra low sulfur and extra high calorific value.For a long time,Haishiwan coal production is still based on the simple and extensive production mode of "digging and selling coal".Commodity coal is mainly used as power coal and coking coal blending High-quality coal resources have not been fully utilized.Studying the technology of preparing ultra-low ash pure coal from Haishiwan coal is of great significance for improving the level of coal processing and transformation,speeding up the transformation of coal from single fuel to both raw material and fuel,and giving full play to the advantages of high-quality coal resources.In this paper,Haishiwan coal is taken as the research object.After screening floatation and sinking experiments,it is found that the ash content of raw coal with 6-0.5mm grain size is between 10%and 11%,which accounts for 30%of the yield of raw coal.Floating and sinking tests showed that the density grade of-1.4g/cm3 accounted for 78.63%of the yield while ash content was only 3.1%.It is an ultra-low ash clean coal.Then the ultra-low ash clean coal with density less than-1.4g/cm3 was used as time research object,which was crushed to below 0.5,and its particle size analysis,density analysis,infrared analysis,X-ray analysis,microscopic analysis and wettability analysis were carried out.The experimental results show that the minerals in the Haishiwan coal mainly include quartz,silicate minerals and pyrites,the main way to prepare ultra-pure coal is to separate these inorganic minerals from organic matter,while the hydrophobic degree of raw coal decreases due to the presence of these minerals.The particle size analysis shows that inorganic minerals are more easily broken than organic matter,and the finer the particle size,the higher the degree of coal sample dissociation.Therefore,in order to effectively enhance the separation of inorganic minerals and organic matter,the first step is to fully dissociate them.Then,by optimizing the surface properties of clean coal particles,the clean coal can be effectively sorted.In order to separate inorganic minerals from organic minerals effectively,grinding of the original sample is the first step.The results of grinding test show that the wet grinding with dispersant additions takes 4 hours,and the grinding medium ratio is higher when the relative content of grinding medium with small particle size is higher,the grinding effect is better.In order to effectively separate inorganic minerals from organic minerals,it is first necessary to grind the original.The results of grinding test showed that the grinding effect is better when the wet grinding is carried out for 4 hours with dispersant and the grinding medium ratio is higher with small particle size.The results of conventional flotation experiments show that the amount of collector diesel is 1000g/t,the amount of foaming agent is lkg/t,the concentration of coal slurry is 50g/L,the aeration amount is 0.25m,/h,and the stirring strength is 2500r/min.The yield was 59.34%,the ash content was 0.81%,the tail coal yield was 40.66%,the ash content was 9.61%,and the flotation improvement index was 50.58%,which was the highest compared with the surrounding point data.The flotation effect of surfactant added during the flotation experiment was significantly better than that of the conventional agent.The yield of clean coal increased from 59.04%to 74.33%,and the flotation improvement index increased from 50.64%to 59.41%.The results of selective flocculation flotation experiments showed that the foaming agent octanol was 1kg/t,the coal slurry concentration was 50g/L,the aeration amount was 0.25m3/h,the stirring strength was 2800r/min,the stirring time was 2min,and the flocculation stirring speed was 2500r/min,flocculation stirring time 4min,using 8 million anionic PAM dosage 20g/t,flocculation flotation effect is best,the flotation improvement index is 59.40%,clean coal yield 71.84%,clean coal ash 0.92%.According to the experimental results,the addition of the nonionic surfactant Triton X-100 has a better flotation effect on the preparation of ultrapure coal,and the process is simple,but the cost of the medicament is high;The selective flocculation flotation experiment also has a better flotation effect,and the cost of the medicament is lower,but the process is more complicated than the former.If industrial production is required,further experimental optimization is needed to determine the most reasonable preparation process.