Experimental Study On Deashing Of Fine Slag From Coal Gasification By Grinding Flotation

Gasification ash slag is a typical industrial solid waste,This paper discusses the current development and utilization status of gasification ash slag,and studies the gasification fine slag with the purpose of recycling the gasification fine slag residue carbon.The fine slag of coal water slurry gasification is taken as the research object,and the basic properties of the fine slag are analyzed,including industrial analysis,granularity and density analysis,mineral composition,micro morphology,functional group composition and pore characteristics.It is shown that the organic carbon connection in the sample is porous,and the inorganic and carbon residues coexist in these pores or are mixed with each other.Average pore diameter of gasification fine slag pore is 3.99 nm,the specific surface area is 191.10 m2/g.After high temperature gasification,many-C=O,-OH and-COOH groups were formed on the coal surface,reducing the hydrophobic on the surface of coal particles.The inorganic impurities in the samples are mainly quartz,calcium carbonate and other minerals.The raw coal minerals with regular crystal structure after high temperature gradually turn into an amorphous state and integrate with the surrounding substances.For the physical and chemical characteristics of high ash,porous gasification slag and surface oxidation,the experiment was firstly studied and combined with flotation.Using wet ball mill and wet rod mill,three kinds of experiments were carried out on gasification fine slag:grinding-grading,grinding-desliming-regrinding-flotation and grinding-non-desliming-flotation.Grinding-grading experiments show that wet ball grinding and wet rod grinding concentrate on the granularity and ash.The rod grinding effect is better than that of the ball mill,and the best effect of ash concentration is different in the grinding time.From the perspective of grinding deash(sludge),gasification slag of 3min fine mud(-0.075mm material)of 70.38%and efficiency of 61.91%;ball grinding 2 min fine plaster can reach 70.10%and removal efficiency 59.03%.The flotation experiment of grinding fine slag showed that the grinding-desliming-regrinding-flotation can obtain yield of 8.16%,ash of 19.48%concentrate,improvement index is only 3.59%;grinding-non-desliming-flotation.can obtain yield of 15.66%,ash of 41.16%concentrate,the improvement index is 7.96%.The grinding ash experiment shows that the grinding mine has an enrichment effect on ash,but the buoyancy of gasification slag is not greatly improved,and the flotation improvement index is low,indicating that the granularity does not the main factor affecting the removal of gasification slag.In view of the poor flotation effect after grinding,flotation for desliming of gasification fine slag is carried out directly from the perspective of flotation reagents.The conventional flotation results show that the kerosene catch effect is better than that of diesel oil,and the foaming effect of methyl isobutyl methanol(MIBC)is significantly better than that of mesoctanol and No.2 oil.Optimum operating conditions:dosage of catch kerosene of 9k g/t,foaming agent MIBC dosage of 4k g/t,slurry concentration of 50 g/L,mixing speed of 2100 r/min and inflation capacity of 0.20 m3/h.Based on conventional flotation conditions,the flotation effect was optimized by adding self-carrier,inhibitor,inorganic salt and surfactant,and the results showed that the flotation effect was better by adding inorganic salt and non-ionic surfactant.The flotation process test was conducted by the combination regulation of CaCl2 and TX-100.The flotation improvement index was 45.92%and the recovery rate of combustible body was 75.87%.The process test shows that three groups of products can be obtained by the sorting-grading process of "one coarse and two fine+coarse tail grading".The yield of refined coal products is 22.39%,25.99%;medium coal yield of 49.84%and ash of 42.52%;yield of 27.77%and ash of 93.74%.The burning loss and fineness index of high ash tail coal can meet the requirements of national standard and grade fly ash mixing mortar and concrete respectively.