In this study, mineralogical and strategic magnetic beneficiation tests were undertaken on a complex low grade saprolite ore to assess the feasibility of recovering valuable rare earth elements (REE) minerals. Mineralogical characterisation tests revealed that bastnäsite was the main REE mineral, with significant amount of La-Nd-Si/Fe intergrowths. The bulk of the ore was occupied by clay and silicate minerals including mica, quartz, K-silicates, and Na-silicates. Subsequently, magnetic separation tests were conducted on the ore using a wet high intensity magnetic separator (WHIMS), where the relative effects of applied magnetic field intensity, matrix type, feed mass, feed desliming, and concentrate regrinding on REE minerals recovery were investigated. Experimental results showed that increasing magnetic field intensity and using fine expanded metal matrix enhanced REE minerals recovery, although concentrate grade was compromised. Additionally, different magnetic separation flowsheets employing regrinding and desliming stages were tested. The highest concentrate grade of 9.12 % total rare earth oxide (TREO) was achieved when the deslimed feed was processed at 1.7 T with the WHIMS fitted with the medium expanded metal matrix mesh, where 86 % REE recovery was observed. A beneficiation process flow sheet for recovering and upgrading REE minerals in the low-grade saprolite ore has been proposed, which recovered 74 % REE assaying a concentrate grade of 9.12% TREO . It was observed that the recovery of mica, entrainment recovery of liberated and unliberated silicate minerals and the presence of bastnäsite/REE-silicates intergrowths limited the extent of TREO upgrade that could be achieved although recoveries were high. The present study provides information on the process mineralogical data of the ore, whiles establishing the technical feasibility of employing magnetic preconcentration conditions to recover valuable REE minerals and identifying other preconcentration strategies which could be utilized in subsequent studies.

中文翻译：

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用于稀土元素矿物回收的复杂低品位腐泥石矿石的表征和磁选

在这项研究中，对复杂的低品位腐泥岩矿石进行了矿物学和战略磁选矿测试，以评估回收有价值的稀土元素 （REE） 矿物的可行性。矿物学特征测试表明，氟碳铈矿是主要的稀土矿物，具有大量的 La-Nd-Si/Fe 共生。大部分矿石被粘土和硅酸盐矿物占据，包括云母、石英、钾硅酸盐和钠硅酸盐。随后，使用湿式高强度磁选机 （WHIMS） 对矿石进行磁选测试，研究了施加磁场强度、基质类型、进料质量、进料脱泥和精矿重磨对稀土矿物回收的相对影响。实验结果表明，增加磁场强度和使用细膨胀金属基体可以提高稀土矿物的回收率，尽管精矿品位受到影响。此外，还测试了采用重研磨和脱泥阶段的不同磁分离流程。当脱泥进料以 1.7 T 的速度加工脱泥进料时，达到 9.12% 的总稀土氧化物 （TREO） 的最高精矿品位，其中安装了中等膨胀金属基网，观察到 86% 的稀土回收率。提出了一种用于回收和提纯低品位腐泥石矿石中稀土矿物的选矿工艺流程，其中回收了 74% 的稀土元素，精矿品位为 9.12% TREO。据观察，云母的回收、释放和未释放的硅酸盐矿物的夹带回收以及氟碳铈矿/稀土-硅酸盐共生的存在限制了尽管回收率很高，但可以实现的 TREO 升级的程度。 本研究提供了有关矿石过程矿物学数据的信息，同时确定了采用磁性预浓缩条件回收有价值的 REE 矿物的技术可行性，并确定了可用于后续研究的其他预浓缩策略。