Arsenic Leachability of Coal Fly Ashes from Different Types of Coal Fired Power Plants

Journal of materials science & engineering Pub Date : 2017-08-28 DOI:10.17265/2161-6213/2017.7-8.001

S. Hartuti, S. Kambara, A. Takeyama

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引用次数: 3

Abstract

The leaching behavior of arsenic (As) in coal fly ash collected from two different types of coal fired power plants (unit 1 and unit 2: 600 MWe) has been investigated to understand their behavior during combustion and effect of different boiler types on arsenic leachability. To determine dominant factors on arsenic leaching from coal fly ash, the change of arsenic chemical during coal combustion was predicted from the perspective of thermodynamic equilibrium and leaching test under alkaline condition. It found that, arsenic leaching fractions in unit 1 were higher than that of unit 2, it is associated with the amount of reactive CaO (calcium oxide) containing in coal fly ash from unit 1 was lower than that from unit 2. As2O3(gas) formed in the boiler reacts with CaO in the fly ash to form calcium arsenate Ca3(AsO4)2 which is thermodynamically stable calcium-arsenic compound. Hence the coal fly ash from unit 2 having higher CaO/Ash ratios generates more Ca3(AsO4)2 and has lower As leaching fraction than that from unit 1. CaO/Ash ratios were a promising index to reduce arsenic leachability from fly ash.

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不同类型燃煤电厂飞灰的砷浸出性

研究了两种不同类型燃煤电厂(1号机组和2号机组:600 MWe)收集的煤飞灰中砷的浸出行为，以了解其在燃烧过程中的行为以及不同锅炉类型对砷浸出性的影响。为确定煤飞灰中砷浸出的主导因素，从热力学平衡和碱性条件下的浸出试验的角度预测了煤燃烧过程中砷的化学变化。研究发现，1号机组的砷浸出分数高于2号机组，这与1号机组飞灰中活性氧化钙含量低于2号机组有关。锅炉内形成的As2O3(气体)与粉煤灰中的CaO反应生成砷酸钙Ca3(AsO4)2，是一种热力学稳定的钙砷化合物。因此，CaO/灰分比较高的2号机组粉煤灰比1号机组粉煤灰产生更多的Ca3(AsO4)2, As浸出率较低。CaO/灰分比是降低粉煤灰中砷浸出率的理想指标。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Journal of materials science & engineering

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