Abstract
The demand for lithium, tantalum, and niobium has soared in the past two decades leading to their classification as ‘critical metals’ in many jurisdictions. Lithium-Cesium-Tantalum (LCT) pegmatite deposits are an important source of these metals. Among the main challenges in the beneficiation of pegmatite deposits are hard mineral contents and finer liberation, which require fine grinding, increasing comminution costs. Therefore, it is necessary to develop an energy-efficient separation process to recover Li, Ta, and Nb-bearing minerals from these deposits. This project aims to apply the SelFrag (Selective Fragmentation) technology to improve the processing of an LCT pegmatite through pre-weakening of the ore prior to comminution. The ore was prepared using two methods: (1) direct mechanical fragmentation (jaw crusher, roll crusher, rod mill); and (2) pre-weakening by high voltage pulses (SelFrag), followed by mechanical fragmentation. For the conventionally ground ore, 15% of the Li, Ta, and Nb reported to the -20 µm fraction; after SelFrag, this was reduced to only 5%. Heavy liquid separation revealed that gravity concentration was promising as a means of pre-concentration only, and further processing was required to produce a salable concentrate. In the case of the SelFrag pretreated ore, shaking table tests resulted in Ta/Nb recovery of ~50% and Li2O recovery of 33%, compared with only 30% Ta/Nb recovery and 12% Li2O recovery when using directly ground ore. Thus, pretreatment by SelFrag reduced grinding energy, decreased the generation of fine particles during grinding, and improved mineral liberation, thereby increasing the separation performance.