论文部分内容阅读
Experimental data show that the Ce-family REE are more accessible to hydrolysis than the Y-familyREE,and the optimum pH conditions for REE adsorption vary from one system to another,for example,pH=3—6 for the chloride system,and 3—4 for the ac■tate system.At pH=3—6,no obvious selectiveBEE adsorption is observed in both the systems.From the deep levels of the weathered crust towards thesurface the percent content of the Ce-family REE tends to increase progressively,whereas that of the Y-family BEE tends to decrease,with La/Ce varying from<1→>1→<1.More or less fractionation wouldtake place among the rare-earth elements due to their different geochemical behaviors.Nevertheless,theREE distribution patterns in the weathered crust can still reflect the REE distribution patterns in the parentrocks.Relatively unstable independent REE minerals,such as bastinaesite,parisite and britholite areconsidered as the main source of rare-earth elements in the weathered crust of this area.
Experimental data show that the Ce-family REE are more accessible to hydrolysis than the Y-familyREE, and the optimum pH conditions for REE deposition vary from one system to another, for example, pH = 3-6 for the chloride system, and 3 -4 for the ac ■ tate system. At pH = 3-6, no obvious selectiveBEE adsorption is observed in both the systems. Flash the deep levels of the weathered crust towards the surface of the percent content of the Ce-family REE tends to increase progressively , that that of the Y-family BEE tends to decrease, with La / Ce varying from <1 →> 1 → <1. More or less fractionation wouldtake place among the rare-earth elements due to their different geochemical behaviors. Yet, theREE distribution patterns in the weathered crust can still reflect the REE distribution patterns in the parentrocks.Relatively unstable unstable REE minerals, such as bastinaesite, parisite and britholite areconsidered as the main source of rare-earth elements in the weathered crust of this area.