高硫铝土矿非等温分解动力学研究
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摘要
高硫铝土矿资源利用的前提是脱硫,开展高硫铝土矿焙烧反应动力学研究是焙烧脱硫技术开发的基础。在N_2+O_2混合气氛中,对贵州高硫铝土矿进行非等温热分析和红外联用分析试验,通过TG、DTG和FTIR分析高硫铝土矿的热分解反应的种类、反应过程和主要特征,采用Flynn-Wall-Ozawa法、Kissinger法、一般积分法和Satava-Sestak法求解反应机理、活化能和指前因子。研究结果表明:高硫铝土矿煅烧过程中主要包括脱羟、脱碳和脱硫三类化学反应。脱羟反应主要是铝土矿和高岭石的脱水,发生的温度范围为400～600℃。脱碳反应主要是有机碳的燃烧和方解石的分解,对应的温度范围分别为400～600℃和700～860℃。脱硫是黄铁矿的分解产生的,对应的温度范围是400～580℃。主要煅烧反应过程符合随机成核与生长机理,机理函数为A3/2,平均表观活化能为197. 05 kJ·mol~(-1)。
Desulfurization is the prerequisite of high sulfur bauxite comprehensive utilization. Researches on roasting reaction kinetics of high sulfur bauxite provide foundations for developing a new desulfurization technology. Coupling test of non-isothermal decomposition thermal analysis and Flourier transform infrared( FTIR) spectrum analysis was carried out in the mixed atmosphere of N2+ O2 for high sulfur bauxite from Guizhou. The types,process and main characteristics of reaction occurring during oxidation roasting process of high-sulfur bauxite were comprehensively analyzed and studied by TG,DTG,DSC and FTIR. The reaction mechanism,activation energy and pre-exponential factor were solved by Flynn-WallOzawa method,Kissinger method,general integral method and Satava-Sestak method. The results showed that the decomposition process mainly includes three kinds of chemical reactions, including dehydroxylation,decarbonization and desulfurization. Dehydration is mainly due to dehydration of bauxite and kaolinite,and the temperature range is 400-600 ℃. The decarburization reaction is mainly due to the combustion of organic carbon and the decomposition of calcite. The corresponding temperature ranges are400-600 ℃ and 700-860 ℃. Desulfurization is mainly due to pyrite decomposition, and the corresponding temperature range is 400-580 ℃. The main reaction process accords with the mechanism of random nucleation and growth. The mechanism function is A3/2,and the average apparent activation energy is 197. 05 kJ·mol~(-1).
Desulfurization is the prerequisite of high sulfur bauxite comprehensive utilization. Researches on roasting reaction kinetics of high sulfur bauxite provide foundations for developing a new desulfurization technology. Coupling test of non-isothermal decomposition thermal analysis and Flourier transform infrared( FTIR) spectrum analysis was carried out in the mixed atmosphere of N2+ O2 for high sulfur bauxite from Guizhou. The types,process and main characteristics of reaction occurring during oxidation roasting process of high-sulfur bauxite were comprehensively analyzed and studied by TG,DTG,DSC and FTIR. The reaction mechanism,activation energy and pre-exponential factor were solved by Flynn-WallOzawa method,Kissinger method,general integral method and Satava-Sestak method. The results showed that the decomposition process mainly includes three kinds of chemical reactions, including dehydroxylation,decarbonization and desulfurization. Dehydration is mainly due to dehydration of bauxite and kaolinite,and the temperature range is 400-600 ℃. The decarburization reaction is mainly due to the combustion of organic carbon and the decomposition of calcite. The corresponding temperature ranges are400-600 ℃ and 700-860 ℃. Desulfurization is mainly due to pyrite decomposition, and the corresponding temperature range is 400-580 ℃. The main reaction process accords with the mechanism of random nucleation and growth. The mechanism function is A3/2,and the average apparent activation energy is 197. 05 kJ·mol~(-1).
引文
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[3]彭欣,金立业.高硫铝土矿生产氧化铝的开发与应用[J].轻金属,2010(11):14-17.
[4]陈咏梅,李江江,许鑫,等.高硫铝土矿氧化焙烧脱硫的节能条件优化[J].河南大学学报,2014,44(3):286-291.
[5]陈延信,赵博,酒少武,等.高硫铝土矿分散态焙烧脱硫实验研究[J].轻金属,2013(12):9-13.
[6] Chen S H,Gong W Q,Mei G J,et al. Primary biodegradation of sulfide mineral flotation collectors[J]. Miner Engineering,2011,24(8):953-955.
[7]李名新,陈肖虎,王帅,等.高硫铝土矿微波脱硫机理研究[J].轻金属,2015(1):16-19.
[8]兰军,吴贤熙,解元承,等.铝土矿生产氧化铝过程脱硫方法的研究进展[J].应用化学,2018,37(4):446-448.
[9] Liu Z W,Li W X,Ma W H,et al. Conversion of sulfur by wet oxidation in the Bayer process[J]. Metallurgical and Materials Transactions B,2015,46(4):1702-1708.
[10] Hu X L,Chen W M,Xie Q L. Sulfur phase and sulfur removal in high sulfur-containing bauxite[J]. Trans Nonferrous Metals Society of China,2011,21(7):1641-1647.
[11]胡荣祖,史启桢.热分析动力学[M].北京:科学出版社,2001.
[12] Ptacek P,Kubatova D,Havlica J,et al. The non-isothermal kinetic analysis of the thermal decomposition of kaolinite by thermogravimetric analysis[J]. Powder Technology,2010,204(2-3):222-227.
[13] Kissinger D E. Reaction kinetic in differential thermal analysis[J]. Analytical Chemistry,1957,29(11):1702-1706.
[14] Ozawa T. Kinetic analysis of derivative curves in thermal analysis[J]. Jounal of Thermal Analysis,1970,2(3):301-324.
[15]李光辉.硅铝矿物的热行为及铝土矿石的热化学活化脱硅[D].长沙:中南大学,2002.
[16] Xu X H,Lao X B,Wu J F,et al. Microstructural evolution,phase transformation,and variations in physical properties of coal series kaolin powder compact during firing[J]. Applied Clay Science,2015,115(10):76-86.
[17]周红,曾文明,陈启元.合成一水硬铝石热分解动力学的DSC研究[J].中国有色金属学报,1993(4):40-43.