粉煤灰中稀土元素的浸出及动力学分析

Leaching of rare earth elementsfrom fly ash and kinetics analysis

以粉煤灰为原料,经过碳酸钠焙烧活化,以盐酸为浸出剂,探究了浸出温度、浸出盐酸的浓度、浸出时间、焙烧时间以及浸出固液比对粉煤灰中镧、铈、钕3种稀土元素的最佳浸出实验条件,并进行了浸出过程动力学分析。实验结果表明:粉煤灰在850℃条件下和碳酸钠以质量比为1∶1混合焙烧180 min后,在90℃的条件下,用5 mol/L的盐酸溶液且固液比为1∶25浸出120 min,镧、铈、钕最佳浸出率分别可达到56.4%、99.99%和99.99%。采用缩心模型对浸出动力学数据进行拟合,结果显示,浸出过程受扩散控制。从粉煤灰中发现并提取稀土元素可以“化害为利,变废为宝”,同时也为稀散金属资源提供了来源,这对于中国矿产资源的保护和清洁高效利用具有重要的实际意义。

Fly ash is a kind of solid waste discharged from coal after combustion.China is a major coal-burning country.Therefore,fly ash is also one of the main pollutants in China.If it is not handled properly,it will cause damage to the environment of our country.,The ecology,the people have serious harm.However,fly ash is rich in various valuable metals and trace rare earth elements.In recent years,my country’s rare earth resources are in urgent need,so fly ash is a potential mineral rare earth resource.It mainly introduces the best roasting and leaching experimental conditions for the recovery of lanthanum,cerium and neodymium from fly ash,and the kinetic analysis during the leaching process.In this experiment,from the five aspects of leaching temperature,leaching hydrochloric acid concentration,leaching time,roasting time and solid-liquid ratio of leaching,it is concluded that fly ash and anhydrous sodium carbonate are combined in a tube furnace at a temperature of 850℃.Roast a homogeneously mixed mixture with a mass ratio of 1∶1 for 180 minutes,and the resulting calcined sample is leached for 120 minutes with a 5mol/L hydrochloric acid solution and a solid-to-liquid ratio of 1∶25 at 80℃.It has the best leaching effect on lanthanum,cerium and neodymium.The kinetic model of acid leaching reaction shows that the leaching process is controlled by diffusion.