模拟原地浸出过程中离子吸附稀土矿孔隙结构和渗透性的变化:新形成的粘土颗粒及其膨胀的影响

IF 4.8 2区 材料科学 Q1 METALLURGY & METALLURGICAL ENGINEERING
Lian Zhang , BaoPing Wen , Lingkang Chen , Haixia Chen , Kaixing Wu
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引用次数: 0

摘要

要从离子吸附型稀土(RE)矿石中开采稀土元素(REE),就地沥滤是必不可少的。稀土开采的效率取决于离子吸附型稀土矿石的渗透性,而渗透性受其孔隙结构的控制。然而,目前对浸出过程中稀土矿石的孔隙结构和渗透率的了解还很有限,尤其是对其动态变化、不同孔隙结构参数对渗透率的控制作用、影响因素的作用以及导致变化的机理等方面的了解还很有限。为了研究上述问题,我们通过恒定水头渗透试验,对未扰动离子吸附 RE 矿石样品进行了不同条件下的模拟原位浸出试验研究。浸出条件包括(NH4)2SO4 溶液的浸出时间、浓度和水头。通过 X 射线计算机断层扫描构建了 RE 矿石在浸出前、浸出过程中和浸出后的三维(3-D)孔隙结构,并利用三维图像计算测量了其孔隙结构参数。实验结果表明,RE 矿石的孔隙结构参数和渗透系数的动态变化分为三个不同的阶段:快速还原、不太快速还原和少量还原。实验结果还表明,RE 矿石的渗透系数主要取决于七个孔隙结构参数中的平均配位数,直径大于 30 μm 的孔隙是 RE 矿石中最有效的渗流通道。与浓度相比,浸出液的水头对孔隙结构和渗透率的变化影响更大。对沥滤前后 RE 矿石的颗粒/集料粒度分布和矿物成分进行的分析表明,孔隙结构参数和渗透率的降低主要是由于迁移的粘土和新形成的粘土堵塞了孔口和孔隙,以及后者的膨胀造成的。新形成的粘土是 K 长石和云母与沥滤溶液发生化学反应而分解的产物。这两种来源的粘土呈解离状和聚集状。该研究结果为通过沥滤法开采可再生矿石提供了重要参考。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Variations in pore structures and permeabilities of ion adsorption rare earth ores during simulated in-situ leaching: Effect of newly formed clay particles and their swelling

In-situ leaching is essential for mining rare earth elements (REEs) from ion-adsorption rare earth (RE) ores. The efficiency of RE mining is dependent on the permeabilities of ion-adsorption RE ores, and the permeabilities are controlled by their pore structures. However, the current understanding of the pore structures and permeabilities of the RE ores during leaching is limited, particularly their dynamic variations, the controlling roles of different pore structure parameters on the permeability, the roles of the influencing factors and the mechanisms causing the variations. To investigate the above-mentioned issues, we conducted an experimental study of simulated in-situ leaching on undisturbed ion-adsorption RE ore samples under different conditions via constant waterhead permeability tests. The leaching conditions included leaching time, concentration and waterhead of the (NH4)2SO4 solution. Three-dimensional (3-D) pore structures of the RE ores before, during, and after leaching were constructed via X-ray computed tomography, and their pore structure parameters were measured using 3-D image computation. It was observed that the dynamic variations in both the pore structure parameters and permeability coefficients of the RE ores occurred in three distinct stages: rapid reduction, less rapid reduction, and little reduction. The experimental results also revealed that the permeability coefficients of the RE ores were primarily dependent on the average coordination number among the seven pore structure parameters examined, and that the pore throats larger than 30 μm in diameter served as the most effective seepage channels within the RE ores. The waterhead of the leaching solution had a stronger influence on the variations in pore structures and permeabilities compared to that of the concentration. Analysis of the particle/aggregate size distribution and mineralogical compositions of the RE ores before and after leaching indicated that the decreases in the pore structure parameters and permeabilities were largely attributed to clogging of the pore throats and pores by migrated and newly formed clays, as well as swelling of the latter. The newly formed clays were the products of the decomposition of K-feldspar and mica resulting from chemical reactions with the leaching solution. The clays from the two sources occurred in disaggregated and aggregated forms. The results of this study provide an important reference for the mining of RE ores via leaching.

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来源期刊
Hydrometallurgy
Hydrometallurgy 工程技术-冶金工程
CiteScore
9.50
自引率
6.40%
发文量
144
审稿时长
3.4 months
期刊介绍: Hydrometallurgy aims to compile studies on novel processes, process design, chemistry, modelling, control, economics and interfaces between unit operations, and to provide a forum for discussions on case histories and operational difficulties. Topics covered include: leaching of metal values by chemical reagents or bacterial action at ambient or elevated pressures and temperatures; separation of solids from leach liquors; removal of impurities and recovery of metal values by precipitation, ion exchange, solvent extraction, gaseous reduction, cementation, electro-winning and electro-refining; pre-treatment of ores by roasting or chemical treatments such as halogenation or reduction; recycling of reagents and treatment of effluents.
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