In order to strengthen the leaching procedure,the chemical processes of leaching rare earths (RE) from the weathered crust elution-deposited rare earth ore were investigated frow the viewpoints of kinetics,hydrodynamic and mass transfer.The results show that the leaching hydrodynamics follows the Darcy law.The leaching kinetics can be described by the shrinking core model;the leaching process is controlled by diffusion of porous solid layer;and the mass transfer can be described with Van Deemter equation.This provides a theoretic basis and a scientific approach with high efficiency and optimized extraction conditions in industrial practice.
The rare earth(RE)in weathered crust ores mainly exists as ion-exchangeable phase,approximately 80%.The correlation analysis on partition of 376 samples in ion-exchangeable phase from weathered crust ores was conducted.The results show that partition both among heavy RE elements and light RE elements with high partition appears positive correlation,but partition sums between the heavy RE elements and the light RE elements appear close negative correlation obviously.Clear negative correlations exist between the light RE elements(except Ce)and yttrium(Y).Matrix of correlation analysis on this partition can be divided into three zones.The correlated coefficient variation from negative to positive in zones B and C occurs at Gd,so does that in zones B and A(except Ce,Eu,and Sm),suggesting that RE elements can be divided into two groups with Gd as border.This phenomenon is called Gadolinium-broken effect.
The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores canbe divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaesite and monazite, andthe weathering crust type. Both the Bayan Obo rare earth ore and the Zhushan rare earth ore are a kind of mixed ore, con-sisting of bastnaesite and monazite. Their rare earth partitionings are strongly enriched in light rare earths, where CeO2 is50% and the light rare earth partitioning is totally over 95%. The Mianning rare earth ore as well as the Weishan rare earthis a kind of rare earth ore only having bastnaesite. Their rare earth partitionings are also strongly enriched in light rare earths,in which CeO2 is 47% and the light rare earth partitioning is totally over 94%. For the weathering crust type rare earth ore,there are the Longnan rare earth ore, the Xunwu rare earth ore, and the middle yttrium and rich europium ore. In the Long-nan rare earth ore, which is strongly enriched in heavy rare earths, Y2O3 is 64.83%, and the heavy and light rare earthpartitionings are 89.40% and 10.53%, respectively. In the Xunwu rare earth ore, which is strongly enriched in light rareearths, CeO2 is 47.16%, and the light rare earth partitioning is totally 93.25%. Y and Eu are enriched in the middle yttriumand rich europium ore. Its middle rare earth partitioning is totally over 10%, and Eu2O3 and Y2O3 are over 0.5% and 20%,respectively, which are mainly industrial resources of the middle and the heavy rare earths.
CHI Ru ＇anLI ZhongjunPENG CuiZHU GuocaiXU Shengming
