An overview of coarse particle beneficiation of lithium ores

Spodumene [LiAl(Si2O6)] is the most common and desirable economic lithium-bearing mineral due to its high lithium content. In Canada, there are several spodumene deposits at the development stage that have the potential to help narrow the forecast lithium supply gap stemming from the widespread acceptance and increasing use of electric vehicles. Spodumene processing can be conducted using Dense Media Separation (DMS), flotation or combination of both. If spodumene liberation is sufficient at coarse particle sizes, DMS can be used for primary lithium concentrate production and silicate gangue minerals rejection. If liberation is not sufficient, flotation is then the main processing route for spodumene concentration. Even in cases where DMS is a viable beneficiation option, flotation may still be required to process the DMS middlings and/or the undersize fraction which is outside the particle size range for DMS. Considering flotation as a technique for spodumene beneficiation, there are several alternatives including the use of mechanical flotation cells, column flotation cells, coarse particle flotation cells, and/or Staged Flotation Reactors (SFR), either alone or in combination. Ore sorting can be incorporated at the start of the spodumene flowsheet to remove gangue minerals, particularly amphibole and pyroxene in the early stages. The main objective of flowsheet development for hard rock lithium deposits is to evaluate the ability of these options to produce a spodumene concentrate with a concentrate grade above 6% Li2O, lithium recovery of above 80%, and with the minimum operating and capital cost. This paper aims to describe the various processing options available for the beneficiation of spodumene from hard rock deposits and compare the associated operating and capital costs for each.

• Froth flotation of fine and coarse particles is studied, focusing on cell designs. • Generating micro-bubbles, intensive turbulence, and high gas hold-up are advantages of intensified cells. • Scaling up/down procedures for the intensified cells are found unclear. • Positioning the optimum location of discussed cells in flotation circuits is found challenging. After more than a century applying flotation to the mining industry, two completely different strategies have been introduced for processing purposes. One is the classical approach viz. grinding ores to a certain extent (fine particles) and floating them via conventional mechanical and pneumatic cells i.e., Jameson, Imhoflot™ and Reflux™. This strategy continues because mines face declining cut-off grades, complex and poly-mineralized ores, and they are required to achieve an acceptable degree of mineral liberation. The other school of thought deals with coarse particle processes mainly owing to the low energy requirements, that includes SkimAir® flash, fluidized bed and HydroFloat™ cells. There is no study in the literature to comparatively present the recent developments of flotation apparatuses versus the conventional mechanical cells. To cover this knowledge gap in the literature, the present paper endeavors to critically evaluate these concepts from several points of view, including existing technological advancements, water and energy usage, kinetics, and circuit design. A brief introduction of advanced technologies, along with their applications is presented. The data from literature and case studies showed that the Jameson, Imhoflot™ and recently developed Reflux™ flotation cells can be very effective for recovering fine particles owing to their specific hydrodynamic designs, intensive energy dissipation rate and generation of micron-sized bubbles (100–700 µm). Very low (less than a few minutes) mean particle residence time, high gas-hold up (ca. 50–70 %), no agitation and high efficiency of particle-bubble collision were identified as their main advantages compared to traditional mechanical flotation cells. In addition to their common applications in cleaner stage, these cells were used in pre-flotation and scalping (producing final concentrate from the rougher feed) duties. Their main challenges were recognized as relatively unclear procedure on their scale up/down, optimization and simulation. The HydroFloat™ cell was indicated as a promising technology for recovering coarse particle fraction sizes by taking advantage of the fluidized-bed concept with plug-flow dispersion regime, high particle residence time, and limited cell turbulence. We finally concluded that fine particle flotation may remain as the main focus of re-processing tailings dams, while coarse particle treatment should be the focus of this century to reduce total energy consumptions.

After more than a century applying flotation to the mining industry, two completely different strategies have been introduced for processing purposes. One is the classical approach viz. grinding the ores to a certain extent and floating them via conventional mechanical and recently pneumatic cells e.g. Jameson and ImhoflotTM cells. This strategy continuous because mines face up to declining cut-off grades, complex and poly-mineralized ores, and they require to achieve an acceptable degree of mineral liberation. The other school of mind deals with the coarse particle processes mainly owing to the low energy needs, that includes flash, fluidized bed and HydroFloatTM cells. The third and newest system proposes processing both fine and coarse sizes by flotation machines like oscillating grid flotation (OGC) and Reflux flotation cells. The present paper endeavours to critically evaluate these concepts from several points of view including existing technological elaborations, water and energy usages, kinetics and circuit design. Brief introduction of advanced technologies, along with their applications, were presented. It was revealed that the incorporation of coarse grinding apparatuses, mineralogical techniques together with the technologically applicable classification systems and adapted simulator tools are urgent needs for coarse flotation as the future requirements for mining industries. However, fine particle flotation may remain as the main focus of re-processing tailings dams.

Research on the mechanisms of particle-bubble interaction has provided valuable information on how to improve the flotation of fine (<20 µm) and coarse particles (>100 µm) with novel flotation machines which provide higher collision and attachment efficiencies of fine particles with bubbles and lower detachment of the coarse particles. Also, new grinding methods and technologies have reduced energy consumption in mining and produced better mineral liberation and therefore flotation performance.

Lithium, known as the energy metal of the twenty-first century, has become a fundamental element due to its recent use in rechargeable lithium-ion batteries and electronic devices. It is anticipated that the global demand for lithium will be more than quadruple, from around 700,000 metric tons in 2022 to over 3 million metric tons in 2030. Lithium resources exist in different deposits, including brines, hard-rock pegmatites, and volcanic clays. Among them, hard rock ores are found worldwide, giving them geostrategic advantages over other types of deposits. Typically, the mineral processing of hard-rock lithium ores includes comminution to achieve a high degree of mineral liberation and a combination of dense media separation (DMS), magnetic separation, and froth flotation. This review paper aims to provide a comprehensive overview of mineral processing technologies used for the beneficiation of hard rock lithium ores, focusing on recent advances and identifying areas for further research and development towards a more sustainable lithium production. Also, the need for life cycle assessment (LCA) studies to assess the environmental impacts associated with responsible mining and beneficiation of lithium ores is briefly discussed. LCA results may assist in the acquirement of social license to operate (SLO) by the mining industry and accelerate the implementation of sustainable exploration and mining projects related to energy transition minerals, most of which are located near indigenous people’s land and environmentally sensitive areas.

New directions in flotation machine design

Froth flotation is the dominating mineral beneficiation technique and has achieved great commercial success. This process has also found many applications in other industries where physical separation of materials is needed. However, its high process efficiency is often limited to a narrow particle size range of approximately 10–100 µm. Considerable efforts have been made to extend this size range to the lower limit of a few microns, even submicrons, and the upper limit of 1–2 mm, in response to increased needs for higher process efficiency and expanded applications of flotation. The particle–bubble collision, attachment, and detachment are the most critical steps in the flotation process. These individual elementary processes (microprocesses) and their effects on flotation efficiency are discussed and the most recent findings are reviewed. The low flotation recovery of fine particles is mainly due to the low probability of bubble–particle collision, while the main reason for poor flotation recovery of coarse particles is the high probability of detachment of particles from the bubble surface. Fundamental analysis indicated that use of smaller bubbles is the most effective approach to increase the probability of collision and reduce the probability of detachment.

Beneficiating the low-grade lithium ores to remove the gangue minerals and enhancing their grade is an attractive proposition today. The beneficiation of a low-grade spodumene ore from Eastern Kazakhstan is investigated by dense media separation (DMS) and froth flotation to obtain a concentrated lithium product. DMS processed the −1000/+850 µm and −850/+500 µm size fractions, while fine particle of −74/+38 µm of composite samples was carried out by froth flotation. The lithium content of the ore varies between 0.3 and 0.5% Li2O. In the 1000/+500 µm size fraction of DMS testwork, the highest lithium grade of 6.7% was achieved with a recovery rate of about 35% at a separation specific gravity of 3.0, while 90% of the lithium oxide was recovered in 8% of the mass, with a grade of 5.1% Li2O at a separation specific gravity of 2.8. Most of the gangue (over 90%) was effectively removed at a specific gravity of 2.7 for both coarse size fractions. A maximum lithium recovery of approximately 53% with a highest lithium grade of 1.2% was obtained under reverse flotation condition of 1000 g/t NaOL/DAA, mixture ratio of 1:5, pH 10, and dextrin concentration of 4000 g/t. The zeta potential and XPS measurements revealed that the mixed NaOL/DAA system exhibited limited interaction with the spodumene surface, primarily through weak chemisorption and electrostatic adsorption, which led to a reduction in the thickness of the DAA multilayer.Graphical

Lithium, a vital metal for modern technology, has become a highly sought-after commodity in Nigeria. The country is endowed with significant lithium deposits, particularly in Kaduna, Kwara, and Niger states. These deposits have the potential to support Nigeria's economic growth and meet the increasing global demand for lithium-ion batteries, which are crucial for electric vehicles and renewable energy systems. In Nigeria, lithium-bearing minerals such as spodumene, petalite, and micas have been identified in pegmatites and granites. The deposits in Kaduna, Kwara, and Niger states are particularly promising, with spodumene being the most abundant and economically viable mineral due to its high lithium content (approximately 8 wt% Li2O). The beneficiation of these hard rock lithium deposits in Nigeria is crucial to unlock their economic potential. This paper reviews the current state of lithium beneficiation in Nigeria, including the use of flotation, dense media separation, magnetic separation, and roasting techniques to process spodumene-bearing ores. By leveraging these technologies, Nigeria can position itself as a significant player in the global lithium market, supporting the growth of the electric vehicle industry and renewable energy sector.

Flotation behaviour in reflux flotation cell – A critical review

Forecariah Guinea Mine SA (FGMSA) in Guinea - Conakry mines and processes Iron ore. About 0.5 Mt of tailings material has already been generated with additional 4000 tons generated daily. This paper presents a re-treatment technology for the Iron tailings obtained from the processing plant of FGMSA. Metallurgical tests were carried out on the tailings to determine which process route gives the most satisfactory result in terms of recovery and cost. Two representative samples (FCOPD-01 and FCDOP-02), taking from the tailings, were investigated. Particle Size Distribution (PSD) and chemical composition of various size fractions of representative samples of the tailings were performed. Dense Medium Separation (DMS) and Magnetic Separation (WHIMS) were also performed on a number of size fractions. The initial chemical composition of the various size fractions shows that the highest Fe grades were present in the +1 mm fractions at 58.8% and 58.6% for FCOPD-01 and FCOPD-02 respectively. The PSD of the tailings also indicated a mass yield of 77.9% for the +1 mm fraction and 22.1% for the -1 mm fraction. Contaminant Oxides, such as Al 2 O 3 and SiO 2 tend to be higher in the finer size fractions (-1 mm) of both samples. Result from the DMS analysis performed on the (-4 +0.5) mm fraction shows an underflow mass yields of 45.98% with Fe grade of 65.55% and overflow mass yield of 53.08% with Fe grade of just 13.5%. Magnetic separation (WHIMS) results on the (-4 +0.5) mm samples also gave varied mass yield and Fe grade at different magnetic intensities (3000 Gauss, 6000 Gauss and 10,000 Gauss). However, the highest Fe mass yield and grade produced from the magnetic separation were 18.10% and 50.8% respectively. The results show that DMS technique has the potential to re-treat the tailings at FGMSA. Keywords : Treatment, Iron ore, Tailings, Magnetic separation, Dense Medium Separation

Forecariah Guinea Mine SA (FGMSA) in Guinea - Conakry mines and processes Iron ore. About 0.5 Mt of tailings material has already been generated with additional 4000 tons generated daily. This paper presents a re-treatment technology for the Iron tailings obtained from the processing plant of FGMSA. Metallurgical tests were carried out on the tailings to determine which process route gives the most satisfactory result in terms of recovery and cost. Two representative samples (FCOPD-01 and FCDOP-02), taking from the tailings, were investigated. Particle Size Distribution (PSD) and chemical composition of various size fractions of representative samples of the tailings were performed. Dense Medium Separation (DMS) and Magnetic Separation (WHIMS) were also performed on a number of size fractions. The initial chemical composition of the various size fractions shows that the highest Fe grades were present in the +1 mm fractions at 58.8% and 58.6% for FCOPD-01 and FCOPD-02 respectively. The PSD of the tailings also indicated a mass yield of 77.9% for the +1 mm fraction and 22.1% for the -1 mm fraction. Contaminant Oxides, such as Al2O3 and SiO2 tend to be higher in the finer size fractions (-1 mm) of both samples. Result from the DMS analysis performed on the (-4 +0.5) mm fraction shows an underflow mass yields of 45.98% with Fe grade of 65.55% and overflow mass yield of 53.08% with Fe grade of just 13.5%. Magnetic separation (WHIMS) results on the (-4 +0.5) mm samples also gave varied mass yield and Fe grade at different magnetic intensities (3000 Gauss, 6000 Gauss and 10,000 Gauss). However, the highest Fe mass yield and grade produced from the magnetic separation were 18.10% and 50.8% respectively. The results show that DMS technique has the potential to re-treat the tailings at FGMSA. Keywords: Treatment, Iron ore, Tailings, Magnetic separation, Dense Medium Separation

The diamond-bearing gravels found along South Africa's West Coast are being beneficiated by means of dense medium separation (DMS) to reclaim the alluvial diamonds. Granular ferrosilicon (Fe–Si) is used as the DMS material and at the end of each operation the Fe–Si is reclaimed from the process stream using a magnetic separator and is then recycled but losses of Fe–Si due to attrition, adhesion to the separation products, density changes and changes to the magnetic properties can occur. The gravel obtained from the mining operation is washed and screened before heavy mineral separation. The concentrate, tailings and Fe–Si samples were investigated by means of SEM and Mossbauer spectroscopy to determine where changes to the Fe–Si, or contamination could occur. The composition of the Fe–Si was determined to be Fe (76.1 at.%), Si (20.3 at.%), Mn (1.5 at.%), Al (1.5 at.%) and Cr (0.6 at.%) resulting in a more or less ordered DO3 phase with a calculated composition of Fe3Si for this Fe–Si, consistent with the Mossbauer results where two sextets with hyperfine magnetic fields of 18.6 T and 28.4 T were observed. After DMS, magnetite and ilmenite, the minerals found in the gravel, were still present in the concentrate. In the tailings virtually no magnetite or ilmenite was found and only a doublet, identified as an oxihydroxide, due to the abrasion of the Fe–Si, was found. After magnetic separation, to wash and clean the Fe–Si for re-use, it was found that magnetite and ilmenite were still present in the Fe–Si, which results in a change in density of the Fe–Si, resulting in a higher density and loss of valuable diamonds.

Since the grinding and chemical reagents required for flotation are expensive, coarse particle flotation reduces grinding costs and makes the subsequent process more accessible and cheaper. Recent studies suggest that the flotation of coarse particles using microbubbles has some advantages. However, a thorough analysis of the effectiveness of various flotation parameters and the impact of their interactions on the recovery of coarse particles in the presence and absence of microbubbles has yet to be fully understood. In the current study, the two-level factorial and Box-Behnken experimental designs were performed to characterize, assess, and optimize the implications of seven numerical (sodium oleate, collector; calcium oxide, activator; MIBC, frother; impeller speed; froth depth; pulp concentration; fine particles) and one categorical (microbubbles) independent parameters on the coarse quartz particles. Characterization revealed that froth depth did not significantly affect the flotation recovery of coarse particles in the mechanical laboratory cell. The effects of the variables in the presence of microbubbles revealed that sodium oleate and impeller speed significantly impacted recovery, followed by calcium oxide and fine particles, both of which had a medium influence, and MIBC and pulp concentration, which had a minimal impact. The recovery of coarse particles increased by 92.714% when microbubbles were used, compared to the estimated maximum recovery under ideal conditions of 62.258% without them. From this, it can be concluded that a high coarse particle flotation recovery is possible by optimizing the hydrodynamic conditions and the chemical environment using microbubbles.

Dense medium separation (DMS) using a waste iron powder from a powder metallurgical plant as solid medium was studied to produce a coarse andalusite concentrate from Kuerle andalusite ore. A high-grade, coarse, andalusite concentrate assaying over 92% andalusite was produced by DMS and magnetic separation, which satisfies the market for the production of a high-duty refractory material. It was also found that the viscosity of waste iron powder suspension could be greatly reduced by adding sodium silicate, leading to better DMS efficiency. The main parameters in DMS of Kuerle andalusite ore, namely feed medium density, underflow spigot diameter and feed pressure, have been studied.