基于浮选-化学联合作用对高炭煤的深度脱灰效应研究

Study on deep demineralization effect of high carbon coal based on flotation combined with chemical treatment

煤炭作为化工原材料的应用途径正逐步向精细化、高端化利用转变,将高炭煤深度脱除矿物质制备成超纯煤可以作为高附加值先进炭素材料的原料。以太西无烟煤为原料,采用自制的微泡浮选柱通过Box-Behnken试验设计方法优化浮选试验,借助XRF,XRD和SEM-EDS分析了最佳浮选条件下的浮选精煤,进一步明晰微泡浮选方法深度脱除矿物质的过程和不同矿物质对无烟煤深度脱矿的影响。同时也采用了NaOH-HCl方法深度脱除无烟煤中的矿物质,通过XRD,SEM-EDS分析脱矿样品的性质,明确无烟煤中矿物质的脱除机理以及限制深度脱矿的因素。微泡浮选试验表明,当捕收剂用量3.36 kg/t、起泡剂用量1.81 kg/t和调浆强度4560 r/min时,浮选效果最佳,能得到灰分0.52%、产率66.25%的浮选精煤,由测试表征可知细泥罩盖和粒度小于2μm、有机质占95%以上的连生体颗粒是限制微泡浮选方法深度脱矿主要原因。NaOH-HCl脱灰试验表明,随着样品粒度减小,样品灰分显著降低,当样品的体积平均粒径为8.01μm时,脱矿效果最佳,能得到脱矿率86.81%、灰分0.36%的脱矿样品。而无烟煤中低反应活性的石英和伊利石以及被煤基质包裹的微细硅酸盐矿物影响太西无烟煤的化学深度脱灰。基于微泡浮选方法和NaOH-HCl方法在高炭煤深度脱矿过程中存在的极限问题,提出浮选-化学联合深度脱灰方法对太西无烟煤进一步深度脱灰,首先通过浮选预处理减少石英和伊利石等低反应活性的矿物质总量,再将浮选精煤中存在的矿物质与NaOH反应生成水溶性的硅酸钠和易溶于酸的硅铝酸钠而被脱除,并以此构建了浮选-化学联合方法深度脱灰历程描述模型,最终得到超低灰(0.12%)、高碳、高发热量能制备成高附加值炭材料的超纯煤样品。

The application of coal as raw material for the chemical industry is gradually shifted to the fine and high-end utilization.Ultra clean coal can be prepared by the deep removal of minerals from high carbon coal,which can be used as the raw material of high value-added advanced carbon materials.Using Taixi anthracite as raw material,the flotation experiment equipped by the self-made microbubble flotation column is optimized by Box-Behnken design method.The flotation concentrate under the optimum flotation conditions is analyzed by XRF,XRD and SEM-EDS.The process of deep demineralization by microbubble flotation method and the influence of different minerals on deep demineralization are further clarified.At the same time,NaOH-HCl method is used to deeply remove the minerals in anthracite.XRD and SEM-EDS are used to analyze the properties of de-mineralization samples,and the mechanism of demineralization and the reasons for limiting deep demineralization are further clarified.The microbubble flotation experiment shows that the optimum conditions are as follows:the dosage of collector is 3.36 kg/t,the dosage of frother is 1.81 kg/t,the agitation rate is 4560 r/min,the ash content of concentrate is 0.52%,and the yield of concentrate is 66.25%.The limit of deep demineralization in microbubble flotation are attributed to slime coatings and the existence of composite particles with the particle size of less than 2μm and the organic matter of more than 95%.The results of NaOH-HCl demineralization experiment show that the ash content of sample is decreased significantly with the decrease of sample size.When the average volume size of sample is 8.01μm,the demineralization effect is optimum.The demineralization of 86.81%and ash content of 0.36%can be obtained.The low reactive quartz and illite of Taixi anthracite and the fine silicate minerals coated by coal matrix mainly affect the deep chemical demineralization.Based on the limitation of deep demineralization of high carbon coal in both microbubble flotation methods and NaOH-HCl method,the deep demineralization method of flotation combined with chemical treatment is proposed for further deep demineralization of Taixi anthracite.Firstly,the total amount of minerals with low reactivity such as quartz and illite are reduced by flotation pretreatment.Then the minerals in flotation concentrate react with NaOH to form water-soluble sodium silicate and acid-soluble sodium aluminate silicate.Based on this mechanism,the descriptive model of deep demineralization process is further built up.The ultra-clean coal with ultra-low ash(0.12%),high carbon and high calorific value is finally obtained,which can be used to prepare high value-added carbon materials.