Study on formation mechanism of akermanite in Zhundong coal ash

doi:10.11949/j.issn.0438-1157.20180751

Abstract

Abstract:

The formation mechanism of coal ash minerals in the three typical quasi-east coal processes of burning Tianchi South Mine, Wucaiwan and Yihua was studied at different temperatures by means of tubular furnace test bench. The mineral composition was analyzed by XRD. At 1100℃, there is a large amount of calcium, magnesium and feldspar formation, which is an important mineral in coal ash at 1100℃. The results show that the first step in the formation mechanism of akermanite is the generate of CaSiO₃,then it react with MgO to form the akermanite.Based on the experimental results, the formation mechanism of akermanite was reserached by density functional theory at the B3LYP/6-311G++(d,p), and the kinetic analysis was studied.The results show that the second path during the formation of the wollastonite is easier to carry out,and the decisive step of this reaction is the O atom transfer step of SiO₂ after CaO is bonded to SiO₂. After that, CaSiO₃ is complexed without barrier to form 2CaSiO₃ and reactes with MgO, finally forming Ca₂MgSi₂O₇, in this process, the maximum potential barrier occurs in the rotational step of the atoms after the bonding of 2CaSiO₃ with MgO.

Key words: Zhundong coal, akermanite, density functional theory, kinetic analysis

摘要：

借助管式炉实验台在不同温度下研究了燃烧天池南矿、五彩湾、宜化三种典型准东煤过程中煤灰矿物质的形成机理，并利用XRD手段分析矿物质组成，结果表明：1100℃时有大量钙镁黄长石生成，是1100℃下煤灰中的重要矿物质；钙镁黄长石生成路径的第一步是形成硅灰石，然后再与氧化镁反应形成钙镁黄长石。基于实验结果，采用密度泛函理论在B3LYP/6-311G++（d，p）水平上对钙镁黄长石的生成路径进行研究，并进行动力学分析。结果表明，硅灰石的形成过程中路径2更容易进行，且该反应的决速性步骤是CaO与SiO₂相连成键后，SiO₂上的O原子转移步骤；之后，CaSiO₃进行无势垒络合，形成2CaSiO₃后再与MgO发生反应，最终形成Ca₂MgSi₂O₇，该反应中的最大势垒出现在2CaSiO₃与MgO相连成键后各原子的转动过程中。

关键词: 准东煤, 钙镁黄长石, 密度泛函理论, 动力学分析

CLC Number:

TK16

ZHAI Zhongyuan, JIN Jing, WANG Yongzhen, HOU Fengxiao, YANG Haoran, LI Huanlong. Study on formation mechanism of akermanite in Zhundong coal ash[J]. CIESC Journal, 2018, 69(12): 5266-5275.

翟中媛, 金晶, 王永贞, 侯封校, 杨浩然, 李焕龙. 准东煤灰中的钙镁黄长石生成机理研究[J]. 化工学报, 2018, 69(12): 5266-5275.

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