摘要
在氯化物和醋酸盐体系中,pH=3—9的不同介质条件下,粘粒组分对某些稀土元素的人工吸附实验,其结果得出:粘粒组分对稀土元素不存在明显的选择吸附;pH=3—6氯化物体系中最利于吸附R^(3+),pH=3—4醋酸盐体系中最利于吸附RE^(3+);铈族稀土的水解能力较钇族稀土更强。稀土元素在风化过程中有逐渐向铈族稀土相对富集方向演化趋势。
Described in this paper is a certain REE deposit of ion-adsorption type occurring in the weathered crust of acid volcanic rocks, which is one of the largest REE deposits of commercial impoirtam.ee discovered recently in China. This paper focuses on REE ad-sorption on clay minerals, characteristics of REE distribution, the mechanism of REE variation in the vertical direction, and REE source. Some interesting experimental re-sults have also been obtained on the mechanism of hydrolysis, decomposition-aibsorpltion and adsorption of REE.Experimental data show that the Ce-family REE are more accessible to hydrolysis than the Y-family REE, and the optimum pH conditions for REE adsorption vary from one system to another. For example, the pH values range from 3 to 6 for the chloride system, and 3 to 4 for the acetate system. At pH=3-6, no obvious selective REE adsor-ption is observed in both the systems. Prom the deep levels of the weathered crust two-ards the surface the percent content of the Ce-family REE tends to increase progressive-ly, whereas that of the Y-family REE tends to decrease, with La/Ce varying from, <1 -->1--><1. More or less fractionation would take place among the rare-earth elements due to their different geochemical behaviors. Nevertherless, the REE distribution pat-terns in the weathered crust can still reflect the REE distribution patterns in the pa-rent rocks. Relatively unstable independent REE minerals, such as bastinaesite, parisite and britholite are considered as the main souirce of rare-earth demerits in the weatthered crust of this region.
出处
《地球化学》
CAS
1986年第3期225-234,共10页
Geochimica
