气氛对煤矸石中矿物质高温碳热还原反应的影响
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摘要
利用煤矸石制备复合耐火材料是实现煤矸石高值利用的有效途径之一。以山西平朔煤矸石为研究对象,利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分别研究了1200~1500℃氩气(Ar)和氮气(N_2)气氛下煤矸石中矿物质的碳热还原反应情况,并通过变换两种气体通入次序,研究了气氛通入次序对矿物质碳热还原反应的影响。结果显示,只通入Ar时,高温样品中的莫来石在1300℃时开始发生碳热反应生成碳硅石(SiC);只通入N_2时,莫来石在1300℃时发生碳热还原氮化反应生成β-Sialon相(Si_5AlON_7)和刚玉相(Al_2O_3);当先通入Ar并停留1 h后通入N_2停留2 h时,样品中生成的碳硅石在通入N_2后转化为β-Sialon相,而且中间体碳硅石的生成能够明显促进莫来石向β-Sialon相的转化。当煤矸石中碳含量较低时,热处理过程中难以同时生成SiC相和Sialon相。高温下煤矸石样品中β-Sialon相的生成使样品表面的棒状颗粒增多。
Producing refractory material by coal gangue is one of the effective ways to realize the highvalue utilization of coal gangue. The carbothermal reduction reaction of mineral matters in Pingshuo coal gangue at high temperature( 1200-1500 ℃) under different atmospheres and effect of atmosphere on the mineral transformation were investigated by X-ray diffraction and scanning electron microscopy. Results show that the mullite in high-temperature coal gangue samples reacts with carbon to form moissanite( SiC) above 1300℃ under argon atmosphere; while,the mullite transforms to β-Sialon( Si_5AlON_7) and corundum( Al_2O_3) above 1300 ℃ under nitrogen atmosphere. The formation of moissanite in samples could accelerate the transformation of mullite to β-Sialon when the coal gangue was firstly heated under argon atmosphere and then was heated continuously under nitrogen atmosphere. The moissanite and β-Sialon were difficult to be formed simultaneously in the coal gangue with low carbon content at high temperature. The β-Sialon in the high-temperature samples presents rod shape.
Producing refractory material by coal gangue is one of the effective ways to realize the highvalue utilization of coal gangue. The carbothermal reduction reaction of mineral matters in Pingshuo coal gangue at high temperature( 1200-1500 ℃) under different atmospheres and effect of atmosphere on the mineral transformation were investigated by X-ray diffraction and scanning electron microscopy. Results show that the mullite in high-temperature coal gangue samples reacts with carbon to form moissanite( SiC) above 1300℃ under argon atmosphere; while,the mullite transforms to β-Sialon( Si_5AlON_7) and corundum( Al_2O_3) above 1300 ℃ under nitrogen atmosphere. The formation of moissanite in samples could accelerate the transformation of mullite to β-Sialon when the coal gangue was firstly heated under argon atmosphere and then was heated continuously under nitrogen atmosphere. The moissanite and β-Sialon were difficult to be formed simultaneously in the coal gangue with low carbon content at high temperature. The β-Sialon in the high-temperature samples presents rod shape.
引文
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[2]薛向欣,张淑会,段培宁.工业固体废弃物作为合成Si基陶瓷原料的开发与利用[J].硅酸盐通报,2005,24(2):72-75.
[3]段锋,刘民生,马爱琼,等.由煤矸石制备塞隆材料的反应条件研究[J].西安建筑科技大学学报(自然科学版),2013,45(5):744-748.
[4]Luo X Y,Sun J L,Deng CJ,et al.Synthesis ofβ-Sialon from coal gangue[J].Journal of Material Science and Technology,2003,19(1):93-96.
[5]张海军,刘战杰,钟香崇.煤矸石还原氮化合成O'-Sialon及热力学研究[J].无机材料学报,2004,19(5):1129-1137.
[6]马刚,岳昌盛,郭敏,等.采用煤矸石和用后Al2O3-Si C-C铁沟料合成β-Sialon[J].耐火材料,2008,42(4):274-278.
[7]岳昌盛,郭敏,张梅,等.高纯β-Sialon粉料的可控合成[J].无机材料学报,2009,24(6):1163-1167.
[8]曹珍珠,潘伟,房明浩,等.碳热还原氮化煤矸石制备β-Sialon结合复相陶瓷粉体[J].稀有金属材料与工程,2002,31(9):28-31.
[9]韩兵强,李楠,杨立平.用煤矸石和煤合成β-Si C-Al2O3的研究[J].耐火材料,2000,34(4):207-209.
[10]王长春,叶方保,钟香崇.用煤矸石制备Al2O3-Si C复相粉体的研究[J].耐火材料,2008,42(4):241-245.
[11]Wang J,Morishita K,Takarada T.High-temperature interactions between coal char and mixtures of calcium oxide,quartz and kaolinite[J].Energy&Fuels,2001,15(5):1145-1152.
[12]Ma Z B,Bai J,Wen X D,etal.Mineral transformation in char and its effect on coal char gasification reactivity at high temperatures,part 3:Carbon thermal reaction[J].Energy&Fuels,2014,27(8):3066-3073.
[13]Reifenstein A P,Kahraman H,Coin C D A,et al.Behaviour of selected minerals in an improved ash fusion test:quartz,potassium feldspar,sodium feldspar,kaolinite,illite,calcite,dolomite,siderite,pyrite and apatite[J].Fuel,1999,78:1449-1461.
[14]马志斌,白进,李文,等.高温弱还原气氛下煤灰中矿物质的定量研究[J].燃料化学学报,2016,44(6):641-647.