Research On The High-efficiency Separation And Extraction Of Associated Rare Earths In Phosphate Rock

Rare earth elements（repersenting by“RE”）have excellent properties of light,electricity,magnetism and heat due to their special atomic structure.They can be used to prepare a variety of high and new technology materials,which scientists call"the treasure house of new materials in twenty-first Century".China contains a large number of intermediate and low grade associated rare earth phosphate ores.How to efficiently separate the rare earth and improve the comprehensive utilization rate of the associated rare earth phosphate ore is a hot spot of research.In this study,the associated rare earth phosphate ore in Zhijin,Guizhou was selected.The extraction of rare earth from its phosphate leaching solution was studied by emulsion liquid membrane method and flocculation precipitation method respectively.Because it contains large amounts of metal ions in phosphate rock,and its content is much higher than that of rare earth ions,so when studying the extraction rate of rare earth ions,we must guarantee it has good selectivity at the same time.Based on the extraction rate of rare earth ions,the best experimental conditions were determined considering the extraction rate of rare earth ions and other metal ions.This paper studies the extraction of rare earth ions in the leaching solution of phosphate ore from the emulsion liquid membrane method with LYQ-2 as the flow carrier,and adding iron pretreatment before the emulsion liquid membrane method,it can greatly improve the proportion of the extracted rare earth ions,and greatly reducing the effect of Fe³⁺on the experiment.The influence of the flow carrier,surface active agent,internal water phase and internal oil ratio on the extraction rate and selectivity of rare earth ions was compared.The optimum liquid film formula was determined:LYQ-2 volume fraction 20%,surface active agent T154 volume fraction4%,diluent sulfonated kerosene volume fraction 76%,internal water phase 16 mol.L^-1CH₂O₂,and 1:1 in oil ratio.The effects of water ratio and extraction time at room temperature on the extraction rate and selectivity of rare earth ions were studied.When the ratio of milk to water was 1:10,the extraction rate of RE³⁺could reach85.42%,and it has good selectivity,and the extraction rate of Ca²⁺,Mg²⁺,Al³⁺and Fe³⁺is very low.Meanwhile,after iron removal pretreatment,the extraction rate of impurity Fe³⁺is only 0.79%.When the ratio of milk to water was 1:5,the extraction rate of RE³⁺could reach 92.10%,and after iron removal pretreatment,the extraction rate of impurity Fe³⁺is only 1.24%.In addition,this paper also studied the more convenient flocculation and precipitation method to extract the rare earth ions in the leaching solution of phosphate rock.LYQ-1 was chosen as precipitator,and the complex precipitates formed by LYQ-1 and Fe³⁺had good flocculation and adsorption effect on RE³⁺.The effects of LYQ-1 dosage,pH value of phosphate leaching solution,reaction temperature,stirring intensity and reaction time on the extraction rate were studied.The optimum process conditions were determined:LYQ-1 volume fraction 2.5%,no adjustment of pH value（pH=-0.3）,room temperature condition reaction,reaction time15min.At this time,the extraction rate of rare earth ions can reach 84.26%.In addition,when the pH value is 1.5,the extraction rate of RE³⁺can reach 91.72%,but at the same time,it will improve the extraction rate of Mg²⁺.The separation and recovery of RE³⁺were carried out.When the pH value of the recovered liquid was 1,the content of RE³⁺in the recovery solution was 73.22%of the phosphate leaching solution,and the content of Fe³⁺and Mg²⁺was very low.Rrare earth oxide was20.96%of the solid products obtained after drying and burning.The content of RE³⁺dissolved in this product is 61.37%of the leaching solution of phosphate rock.