摘要
为研究向煤中添加碳酸钙混燃对煤灰中铀赋存形态及矿物组成的影响,选取两种云南临沧煤样进行室内燃烧试验,基于逐级提取方法,采用电感耦合等离子体质谱仪(ICP-MS)分析原煤及煤灰中铀的赋存形态,并结合X射线衍射(XRD)分析、X射线荧光光谱(XRF)分析和差示扫描量热法(DSC),研究了煤中添加碳酸钙混合燃烧对煤灰中铀的赋存形态、化学组成和矿物组成的影响机理。结果表明:随着碳酸钙添加剂量的增加,煤灰中以残渣态形式存在的铀会逐渐转化为碳酸盐结合态铀或铁锰氧化物结合态铀;煤燃烧过程中,碳酸钙的分解产物与赤铁矿反应生成可被盐酸羟胺还原的黑钙铁矿,增加了铁锰氧化物结合态铀,且钙可能进入硅铝酸盐矿物晶格破坏硅氧键,并与之结合生成较石英、长石更易溶的钙铝硅酸盐。因此,煤中添加碳酸钙可以通过改变燃烧后的煤灰中铀的赋存形态和矿物组成来增加其酸溶性,有利于煤灰中铀的回收与利用。
This paper takes two kinds of Lincang uranium-bearing coals as the experimental samples to analyze the influence of calcite mixed coal combustion on uranium occurrence and mineral composition in coal ash.Based on the Tessier sequential extraction method,the paper uses inductively coupled plasma - mass spectrometry (ICP-MS) to detect the uranium contents of different occurrence forms in raw coal and coal ash.Further,the paper applies the X-ray diffraction (XRD),X-ray fluorescence (XRF) and differential scanning calorimeter (DSC) analysis to exploring the CaCO 3 influencing mechanism on the uranium occurrence,chemical composition and mineral composition in coal ash.The results show that the residual uranium decreases by transforming into the carbonate bound uranium and Fe-Mn oxides bound uranium as calcite adding dosage increases,which can be attributed to the reaction between the decomposition product of calcite and hematite.Moreover,the acid solubility of coal ash increases and residual uranium transfers to other leachable forms as the formation of more soluble calcium aluminosilicate.Overall,calcite mixed coal combustion can improve the acid solubility of coal ash and leachable uranium by changing the carbonate and Fe-Mn oxides bound uranium and mineral composition in coal ash.
作者
汤烨
李义连
宁宇
TANG Ye;LI Yilian;NING Yu(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430074,China)
出处
《安全与环境工程》
CAS
北大核心
2019年第4期99-105,共7页
Safety and Environmental Engineering
基金
国家自然科学基金项目(41572233)
关键词
碳酸钙
煤灰
铀赋存形态
矿物转化
calcite
coal ash
uranium occurrence
mineral transformation
