桂西拜耳法赤泥静态淋溶碱释放影响因素试验

Experimental on Influence Factors of Static Leaching Alkali Release from Bayer Process Red Mud in Western Guangxi

为研究桂西拜耳法赤泥中碱的溶出规律及影响因素,采用浸出试验分析了赤泥中碱的赋存状态及含量,通过静态淋溶试验并改变初始溶液pH、固液比、粒径大小、环境温度、是否搅动等条件,研究赤泥中碱释放随时间变化的规律及溶出机制并使用正交分析法分析赤泥中碱释放主要影响因素。结果表明:赤泥中的可溶性碱占总碱含量的30.45%,主要赋存于氢氧化钠、碳酸钠、碳酸氢钠、硅酸钠及可溶钙霞石中;非可溶性碱占总碱含量的69.55%,主要赋存于方钠石及难溶钙霞石中。溶液中初始溶液pH、固液比、溶液温度对赤泥中碱释放影响较大,而是否搅动及赤泥粒径对其影响较小;影响赤泥溶液中碱浓度及碱溶出率的因素依次为液固比、环境温度、初始溶液pH。研究结论可为解决桂西拜耳法赤泥对周边环境效应影响及脱碱提供必要的科学依据。

In order to study the leaching law and influencing factors of alkali from Bayer red mud in Western Guangxi,the occurrence state and content of alkali in red mud were analyzed by leaching test.Through static leaching test and changing initial solution pH value,solid-liquid ratio,particle size,environmental temperature,agitation and other conditions,The variation of alkali release in red mud with time and dissolution mechanism were studied,and the main influencing factors of alkali release in red mud were analyzed by orthogonal analysis.The results show that the soluble alkali in red mud accounts for 30.45%of the total alkali content,and mainly occurs in sodium hydroxide,sodium carbonate,sodium bicarbonate,sodium silicate and soluble nepheline.The insoluble alkali accounts for 69.55%of the total alkali content,mainly occurs in sodalite and insoluble nepheline.The initial solution pH,solid-liquid ratio and solution temperature have great influence on the alkali release from red mud,while agitation and red mud particle size have little influence on it.The factors influencing the alkali concentration and alkali dissolution rate in red mud solution are liquid-solid ratio,ambient temperature and initial solution pH value in turn.The research results can provide the necessary scientific basis for solving the effect of Bayer red mud on the surrounding environment and dealkalization.