渗流问题和边坡稳定性问题是离子型稀土矿床原地浸矿工艺面临的两个基本问题,而颗粒粒度分布被认为是土壤最基本的物理性质之一,对土壤水流动、溶质和颗粒迁移以及水土流失等起关键作用.通过浸矿实验、筛分分析和激光粒度分析研究了离子型稀土矿石颗粒粒度分布特征及其影响因素和变化规律.研究结果表明,离子型稀土矿石颗粒粒度分布受成矿母岩、风化程度、水土流失和颗粒垂向迁移、原地浸矿活动等因素的影响,呈如下变化规律:(1)当成矿母岩为中、粗粒结构,且石英含量高时,稀土矿石颗粒易呈双峰式粒度分布,即微粒组分(＜0.2 mm)和中、粗粒组分(＞2 mm)含量较高,细粒组分(0.2 mm～2 mm)含量相对较低,原地浸矿活动过程中容易造成水土流失和颗粒垂向迁移,并易诱发滑坡灾害;(2)受风化程度和颗粒垂向迁移的影响,稀土矿石微粒组分的含量随深度增大常呈先升后降的抛物线形态;(3)原地浸矿活动可促进稀土矿石的进一步风化,并加剧较细颗粒的垂向迁移,从而影响稀土矿石颗粒粒度分布.
Percolation of extraction solvent and slope stability are the two basic issues confronted by in-situ leaching mining technology of ion-adsorption type of REE deposit.Particle size distribution is considered as one of the most fundamental physical properties of the soil and one of key factors for soil water and grain movement,soil erosion and soil solute migration.It has been studied particle size distribution of ion-adsorption rare earth ore and its influence factors and change rule by leaching experiment,sieving and laser particle size analyzer.It is shown that particle size distribution of ion-adsorption rare earth ore is influenced by parent rock,degree of weathering,soil erosion,grain downward movement,and in-situ leaching mining activity,and the change rule of it is as follows:(1) When parent rock is medium to coarse textured and highly in quartz content,the rare earth ore is often of a bimodal particle size distribution,i.e.,highly in both the finest(＜0.2 mm) and medium to coarse (＞ 2mm) particle components while relatively low in the fine (2 ～ 0.2 mm)particle component,which made it more likely to suffer soil erosion and downward movement of finer grains during the process of in-situ leaching mining activity;(2) Affected by the degree of weathering and downward movement of finer grains,the content of the finest component increases first and decreases afterwards with the increase of depth;(3) In-situ leaching mining activity promotes further weathering of the REE ore and intensifies downward movement of finer grains and thus influences the particle size distribution of the REE ore.
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