浸矿开采对离子型稀土基岩力学特性的影响研究

为研究原地浸矿母液对离子型稀土矿收液底板的侵蚀影响，以离子型稀土矿基岩（半/弱风化花岗岩）为研究对象，开展了室内浸矿模拟试验。对比分析了不同浸矿时间岩样的应力−应变曲线、峰值应力、峰值应变和弹性模量，获取了不同浸矿历时岩样的孔隙度和细观形貌特征，并运用盒维法对岩样的非线性裂纹特征进行了定量化描述。结果表明：浸矿侵蚀作用对离子型稀土矿底板基岩力学性质的影响主要表现在前150 d，破坏形式由贯穿破坏转变为贯穿破坏与片状剥落并存；浸矿母液侵蚀作用下，基岩力学特性呈现先大幅减小后大幅回升，其后在小范围波动现象，浸矿约60 d对基岩力学特性的影响程度最大；浸矿母液侵蚀造成基岩内小孔隙增长，导致表面出现腐蚀及孔洞现象；浸矿时间不同将造成岩石不同的微观结构变化。

Experimental study of the influence of leaching mining on mechanical properties of ionic rare earth ore floor bedrock

In order to study the erosion effect of in-situ leaching mother liquor on the receiving floor of ionic rare earth ore, an indoor leaching simulation test was carried out with the bedrock of ionic rare earth ore (semi/weakly weathered granite) as the research object. The stress-strain curves, peak stress, peak strain and elastic modulus of rock samples for different leaching durations are compared and analysed, the porosity and micro morphology characteristics of rock samples for different leaching durations are obtained, and the nonlinear crack characteristics of rock samples are described quantitatively by box dimension method. The results show that the effect of leaching erosion on the mechanical properties of the bedrock of the floor of ionic rare earth ore is mainly manifested in the first 150 days, and the failure form changes from penetration failure to the coexistence of penetration failure and flaky spalling. Under the erosion of ore leaching mother liquor, the mechanical properties of bedrock first decrease greatly and then rise sharply, and then fluctuate in a small range. About 60 days of ore leaching has the greatest impact on the mechanical properties of bedrock. The erosion of ore leaching mother liquor causes the growth of small pores in the bedrock, resulting in corrosion and holes on the surface. Different leaching durations will cause different microstructure changes of rocks.