Search Results (5)

Due to the increasing demand for lithium resources, the efficient exploitation and utilization of low-grade hard-rock deposits has become an inevitable trend. This study conducted comprehensive heavy liquid separation (HLS), numerical simulation, and dense medium separation (DMS) tests using a laboratory dense medium cyclone (DMC) on a low-grade spodumene ore to demonstrate the potential role of DMS technology in this task. HLS tests verified the feasibility of directly producing qualified concentrate and rejecting waste under different separation densities. A two-stage DMS circuit was then proposed, with the influence of key parameters investigated by numerical simulations using the two-fluid model and dispersed model. The optimized set of structural and operational parameters was finally identified by DMS tests. A continuously operated test conducted on −8 + 0.5 mm ore produced a spodumene concentrate grading 5.68% Li₂O with over 80% lithium recovery while rejecting 0.13% Li₂O waste to tailings with ~70% disposal rate but only 7.44% lithium losses. The middling with a yield of 12.66% can be further subjected to a traditional grinding-flotation process. The findings underscore the importance of parameter matching in the DMS and demonstrate the application potential of DMS in the development of low-grade spodumene from other hard-rock occurrences. Full article

This paper investigated pre-concentration of a low-grade Upper Group 2 (UG2) ore to assess the possibility of rejecting waste at a typical discard Platinum Group Metals (PGMs) grade of <0.4 g/t at mass rejection to floats greater than 16% by comparing feed prepared by High pressure grinding rolls (HPGR) to Conventional crushers (Cone crushers). Heavy Liquid Separation (HLS) was conducted as a benchmark test to Dense Medium Separation (DMS) to determine the expected grade, recovery, and mass yield for various size classes and crusher. The comparison between fine size classes −9.5 + 1.18 mm and −6.7 + 1.18 mm crushed by HPGR and conventional crushing showed that, under the conditions tested, the conventional crusher outperformed HPGR in terms of high sinks grade and a higher percentage of material exposed to pre-concentration. Looking at coarser size fractions (+12 mm), HLS results showed that under the conditions tested, size fraction −20 + 1.18 mm crushed by a conventional crusher at an optimum density of 3.4 g/cm³ is an optimized size fraction to run the DMS plant. The pilot DMS cyclone testwork showed that 61.1% by mass could be rejected to the floats stream based on Run of Mine (ROM) feed at 1.12% Cr₂O₃ and 0.42 g/t Total PGMs + Au grade, a typical discardable PGMs grade. Full article

There is a growing demand for lithium as it is primarily used in the production of batteries. Two lithium bearing ores, namely spodumene and lepidolite, underwent gravity separation via heavy liquid separation (HLS) laboratory tests to determine the amenability of each ore to upgrade by gravity processes, such as dense medium separation (DMS). Each sample was crushed to −20 mm, and the −1 mm fraction was screened out to produce a −20 + 1 mm feed for HLS testwork. A 50/50 composite sample was also created to determine the performance when both ores are treated simultaneously. At a cut point of 2.9 g/cm³, lepidolite, spodumene and the composite achieved %Li₂O grades of 4.28%, 3.38% and 4.59%, at recoveries of 24.6%, 2.77% and 10.1%, respectively. The grade of the composite samples is greater than the theoretical calculated grade, which may be due to the nugget effect of spodumene. At a cut point of 2.8 g/cm³, recoveries are significantly improved (>73%); however, the grade is then compromised. Full article

In coming years, global lithium production is expected to increase as the result of widespread electric vehicle adoption. To meet the expected increase in demand, lithium must be sourced from both brine and hard-rock deposits. Heavy liquid separation (HLS) and dense media separation (DMS) tests were conducted on the pegmatites from Hidden Lake, NWT, Canada to demonstrate the potential role of this technology in the concentration of spodumene (LiAlSi₂O₆) from hard-rock sources. A continuously operated DMS circuit test, conducted on +840 µm material, produced a concentrate grading 6.11% Li₂O with ~50% lithium recovery. The circuit rejected 50% of the original mass to tailings, with only 8% lithium losses. Sensitivity analysis showed that minor changes (+/−0.05) in the DMS-specific gravity cut point resulted in significant changes to the mass rejected and to the concentrate grade produced; this may limit the feasibility and operability of the downstream grinding and flotation circuits. The results demonstrate the potential for DMS in the concentration of spodumene from the Hidden Lake pegmatites, and by extension, the potential for DMS in the concentration of spodumene from other hard-rock occurrences. Full article

The historic Penouta mine in northwest Spain is the focus of efforts to extract tantalum from tin mining waste. This paper describes the characterisation of the tantalum mineralogy of waste material from the deposit. Characterisation was realised using quantitative mineralogy and geochemistry. This paper further identifies other phases of interest and investigates the potential for extraction using gravity separation techniques. The gravity concentrate obtained through these tests was analysed using quantitative mineralogy and electron probe microanalysis. Following characterisation of the sample material to identify the key Ta-bearing mineral phases and assess liberation, a series of gravity separation trials were conducted using Heavy Liquid Separation (HLS), Mozley table, Knelson concentrator separation and shaking table. The laboratory shaking table used to conduct a rougher test and a rougher/cleaner test to simulate a spiral-table circuit using the Penouta material. Mass balance calculations were carried out to calculate the contained metal content of the feed material and concentrate products in order to assess recovery rates for Ta, Sn and Nb across a range of grains sizes. Ta was found to be present predominantly in the solid-solution columbite-group mineral, along with minor Ta present as microlite and as impurities within cassiterite. It was found that over 70% of the Ta is contained within the −125 μm fraction, with the Ta-bearing minerals tantalite and microlite being closely associated with quartz. Mozley table separation resulted in recoveries of 89% Ta and 85% Nb for the −125 μm fraction. The Knelson Concentrator trial was carried out on the −625 μm size fraction, thereby eliminating low grade material found in the coarsest fractions. Size analysis of the recovery rate for each product, shows that the Knelson concentrator is most efficient for recovery of −125 μm particles. Full article