Study On Clay Minerals Of Southern Weathered Rare Earth Deposits

The weathered crust elution-deposited rare earth deposit is one of the important rare earth deposits in China.The identification of the main clay minerals,especially the identification of kaolinite and halloysite-7?,is especially important for the study of this type of deposit.Through actual tests,it can be found that the common methods are the scanning electron microscopy for shape identification and X-ray powder crystal diffraction technology for different sample preparation methods for comparative phase identification.Transmission electron microscopy,Raman spectroscopy and other means cannot be used as the main detection means due to their limitations.This paper is mainly aimed at the differentiation phenomenon of rare earth elements in the weathered crust elution-deposited rare earth deposit.Through the studies on the mineral characteristics and adsorption of kaolinite and halloysite-7?,we simulated the process of adsorption of rare earth elements,and can discuss the genesis of the deposit.According to the results of the experiments,the adsorption capacity of halloysite-7?to rare earth elements is far greater than kaolinite.And when the pH of the system is lower than the point of zero charge of the two minerals or there are metallic cations in the system,the adsorption capacities of both minerals are greatly affected.The results of lateral comparison experiments suggests that regardless of the change of pH or the addition of Na~+in the system,kaolinite and halloysite-7?will not show the characteristics of adsorption dissimilarity and the adsorption patterns to each rare earth elements is relatively similar.Only when K~+is there inside the system the adsorption patterns of both clay minerals to rare earth elements show divergence,among which MREE and HREE were mainly adsorbed by kaolinite while LREE were mainly adsorbed by halloysite-7?.Thus,K~+produced by weathering of rocks makes kaolinite and halloysite-7?having selective adsorptions,and further affects the distribution of REE in the REE deposits.On this basis,this paper selects the ore samples from Jiangxi,Fujian,Guangdong,Zhejiang and other important rare earth mining areas to identify and analyze the types of clay minerals,and uses some experimental methods to measure the contents.Based on the species and content of rare earth elements,the relationship between clay mineral types(mainly kaolinite and halloysite-7?)and rare earth enrichment was discussed.The test results show that all the soil samples in the weathered leaching rare earth ore samples contain kaolinite,and some soil samples containing halloysite-7?are compared with soil samples without halloysite-7?.It does not reflect the obvious characteristics of enriching light rare earth elements.However,the weathering conditions of core samples from different depths in Zhejiang Province are more similar to the original rock conditions and have more reference value.As the sample increases from the surface depth,the halloysite-7?is from nothing,and the content is gradually increased,while the kaolinite content is gradually decreased.At the same time,the surface layer samples contain relatively many medium and heavy rare earths,which is roughly consistent with the conclusion.In the actual metallogenic process,the weathered crust elution-deposited rare earth deposits have a great influence on the distribution of rare earth elements during the weathering process,and the interaction between the various factors affects each other,resulting in a complicated result.The influence of clay minerals on the distribution of rare earth elements is not significant under the interaction of original rock,groundwater,temperature and other factors,but it does have a certain degree of influence.This result is for the study of weathering and leaching rare earth deposits.Mineralization and prospecting are undoubtedly of certain significance.