Optimization Study On The Preparation Process Of Ultra-clean Micronized Coal-oil-water Slurry

Based on the study on the proximate analysis, particle size distribution, densitycomponents, surface structure and physical and chemical properties of the coal, thepossibility of preparation of ultra-clean coal from the coal sample was explored. In thecourse of the preparation of ultra-clean coal by flotation, reagent system, pulp densityand grinding were optimized for research. For the prepared ultra-clean coal, additive,grinding density and grinding time were optimized in the course of ultrafine grinding.And then, pulping study was conducted using ultra-fine ultra-clean coal, in which typeand amount of additives and slurry density were optimized for research.By analyzing coal quality characteristic, we got a few conclusions as follows.Overall, the raw coal has a low ash content. In terms of size distribution, the sizesuitable for flotation recovery has a high content and a low ash, while less selectivefine particles has a high ash and a low content. In terms of density components, rawcoal’s-1.35g/cm3density levels have a higher content accounting for about half andhave a less than1%ash content, at the same time every size level’s+1.425g/cm3density level have a less than10%content and a higher ash except-0.074mm sizelevel. In terms of surface properties, coal particle’surface is relatively dense, uniform,flat, smooth, and has a low mineral content.Ultra-clean coal preparation process was optimized by flotation, in which reagentsystem, flotation crafts, pulp density and grinding were studied. The results showedthat ultra-clean coal with less than1%ash content cannot be obtained through onefloatation and the flotation flowsheet of one roughing and one cleaning must be used.In the roughing process, n-dodecane was chosen as collector with100g/t dosage, and2-octanol was chosen as frother with100g/t dosage. In the cleaning process,100g/twas chosen as collector dosage, and50g/t was chosen as frother dosage. In this case,we can obtained ultra-clean coal with73.46%yield and0.91%ash content. Inaddition, through the grinding process, we can effectively improve the clean coalyield to85.20%with only0.93%ash content.Coal ultrafine grinding process was optimized by using a QM-2laboratory rollermill, in which additive, grinding density and grinding time were studied. The resultsshowed that the CMC is the best additive among CMC, sodium pyrophosphate andSpan-80. Through the test,1.5%was chosen as the CMC dosage and60%was chosenas the grinding density. In this case, we can make grinding products’ D50less than 10μm and D95less than45μm in about3.5hours.Pulping study was conducted using ultra-fine ultra-clean coal, in which type andamount of additives and slurry density were studied. The results showed thatultra-clean micronized coal-oil-water slurry has a lower viscosity and a better stabilitywhen using2%CMC. Under this condition, the slurry density was optimized and theresults showed that the slurry viscosity can still meet the requirements and has a betterstability when the slurry density rises to55%.