Experimental Study and Mechanism Analysis of Modified Limestone by Red Mud for Improving Desulfurization
Red mud is a type of solid waste generated during alumina production from bauxite,and how to dispose and utilize red mud in a large scale is yet a question with no satisfied answer.This paper attempts to use red mud as a kind of additive to modify the limestone.The enhancement of the sulfation reaction of limestone by red mud (two kinds of Bayer process red mud and one kind of sintering process red mud) are studied by a tube furnace reactor.The calcination and sulfation process and kinetics are investigated in a thermogravimetric (TG) analyzer.The results show that red mud can effectively improve the desulfurization performance of limestone in the whole temperature range (1073-1373 K).Sulfur capacity of limestone (means quality of SO2 which can be retained by 100 mg of limestone) can be increased by 25.73％,7.17％ and 15.31％ while the utilization of calcium can be increased from 39.68％ to 64.13％,60.61％ and 61.16％ after modified by three kinds of red mud under calcium/ metallic element (metallic element described here means all metallic elements which can play a catalytic effect on the sulfation process,including the Na,K,Fe,Ti) ratio being 15,at the temperature of 1173 K.The structure of limestone modified by red mud is interlaced and tridimensional which is conducive to the sulfation reaction.The phase composition analysis measured by XRD of modified limestone sulfated at high temperature shows that there are correspondingly more sulphates for silicate and aluminate complexes of calcium existing in the products.Temperature,calcium/metallic element ratio and particle diameter are important factors as for the sulfation reaction.The optimum results can be obtained as calcium/metallic element ratio being 15.Calcination characteristic of limestone modified by red mud shows a migration to lower temperature direction.The enhancement of sulfation by doping red mud is more pronounced once the product layer has been formed and consequently the promoting effect of red mud becomes greater once the sulfation reaction becomes diffusion controlled.This study indicates that red mud from alumina plant is a favorable additive for improving the desulfurization performance of limestone,and the effect of red mud on limestones desulfurization activity is due to superposition of improvement in solid-state ionic diffusion and surface chemical reaction.
red mud additive modification desulfurization kinetics
Hongtao Liu Kuihua Han Shengli Niu Chunmei Lu Mengqi Liu Hui Li
School of Energy and Power Engineering,Shandong University,Jinan 250061,Shandong Province,China
国际会议
The 7th International Symposium on Coal Combustion(第七届国际煤燃烧学术会议)
哈尔滨
英文
318-327
2011-07-19（万方平台首次上网日期，不代表论文的发表时间）