富铝煤矸石低钙烧结法提铝的实验研究  

Experimental Study on Extraction of Aluminum from Aluminum-rich Coal Gangue by Low-calcium Sintering

作　　者：张维涛 陈延信[1] 赵博[1] 宋强[1] ZHANG Weitao;CHEN Yanxin;ZHAO Bo;SONG Qiang(College of Materials Science and Engineering, Xi’an University of Architecture and Technology, 710055 Xi’an, China)

机构地区：[1]西安建筑科技大学材料科学与工程学院,西安710055

出　　处：《煤炭转化》2022年第3期61-70,共10页Coal Conversion

基　　金：国家重点研发计划项目(2016YFB0303400);陕西省重点科技创新团队项目(2021TD-53);陕西省自然科学基础研究计划项目(2019JLZ-05).

摘　　要：以提取富铝煤矸石中的氧化铝为目的,采用低钙烧结法活化煤矸石,研究了烧结温度、烧结时间和碱比(n(Na_(2)O)/[n(Al_(2)O_(3))+n(SiO_(2))+n(Fe_(2)O_(3))])对烧结熟料矿物相、微观结构及氧化铝溶出效果的影响。其中,烧结温度设置6个水平(1000℃,1050℃,1100℃,1150℃,1200℃,1250℃),烧结时间设置6个水平(30 min,50 min,70 min,90 min,110 min,130 min),碱比设置5个水平(0.8,0.9,1.0,1.1,1.2)。根据钙比(n(CaO)/[n(SiO_(2))+n(TiO_(2))])为1.1、碱比为变量配料,在不同烧结温度和烧结时间下进行单因素试验;所得熟料研磨过筛后按照氧化铝标准溶出条件在集热式恒温磁力水浴锅中溶出,得到溶出固相,然后对熟料和溶出固相进行检测分析,得到不同条件下的氧化铝溶出率。对最佳配比的生料,做不同温度下的烧结试验,分析熟料矿物相和微观结构等的变化。结果表明:随温度升高,高岭石脱水生成偏高岭石,在686.71℃完成转变;偏高岭石优先与碳酸钠反应生成硅铝酸钠Na_(2-x)Al_(2-x)Si_(x)O_(4),在石灰石对Na_(2-x)Al_(2-x)Si_(x)O_(4)的分解作用下,Na_(2-x)Al_(2-x)Si_(x)O_(4)中硅的摩尔数x逐渐降低并趋于0,最终形成NaAlO_(2)和Na_(2)CaSiO_(4)矿物;在实验条件下,升高温度、延长时间或增加碱比可促使Na_(2-x)Al_(2-x)Si_(x)O_(4)向NaAlO_(2)转变;而高温、长时间和高碱比易使熟料烧结致密,导致NaAlO_(2)的溶解度下降。在钙比为1.1、温度为1150℃、时间为90 min、碱比为1.1的条件下,氧化铝溶出率达87.51%(质量分数)。In order to extract alumina from aluminum-rich coal gangue,coal gangue was activated by low-calcium sintering.The effects of sintering temperature,sintering time and alkali ratio(n(Na_(2)O)/[n(Al_(2)O_(3))+n(SiO_(2))+n(Fe_(2)O_(3))])on mineral phase,microstructure and alumina dissolution of sintered clinker were studied.Among them,the sintering temperature was set to 6 levels(1000℃,1050℃,1100℃,1150℃,1200℃,1250℃),and the sintering time was set to 6 levels(30 min,50 min,70 min,90 min,110 min,130 min),while the alkali ratio was set to 5 levels(0.8,0.9,1.0,1.1,1.2).Single-factor tests were carried out under different sintering-temperature and sintering-time conditions with calcium ratio(n(CaO)/[n(SiO_(2))+n(TiO_(2))])of 1.1 and alkali ratio as variable ingredients.After grinding and screening,the clinker was dissolved in a heat collection constant temperature magnetic water bath according to the standard dissolution conditions of alumina,and the dissolved solid phase was obtained.Then the clinker and dissolved solid phase were detected and analyzed to obtain the alumina dissolution under different conditions.Sintering tests were carried out with the optimal ratio of raw materials at different temperatures,and the characteristics of the clinker mineral phase,microstructure etc.were analyzed.The results show that kaolinite is dehydrated into metakaolin with the increase of temperature,and the transformation is completed at 686.71℃.Metakaolin reacts preferentially with sodium carbonate to form sodium aluminosilicate Na_(2-x)Al_(2-x)Si_(x)O_(4).Under the decomposition of Na_(2-x)Al_(2-x)Si_(x)O_(4) by limestone,the number of moles of silicon in Na_(2-x)Al_(2-x)Si_(x)O_(4) gradually decreases and tends to be zero,and finally NaAlO_(2) and Na2CaSiO4 minerals are formed.The transformation of Na_(2-x)Al_(2-x)Si_(x)O_(4) to NaAlO_(2) can be promoted by prolonging time,increasing temperature or alkali ratio.However,high temperature,long time and high alkali ratio easily lead to the densification of the clinker,wh

关 键 词：低钙烧结 富铝煤矸石 氧化铝 硅铝酸钠 偏铝酸钠 

分 类 号：TD849.5[矿业工程—煤矿开采]