Mechanical Flotation Cell Research Articles

Statistical Evaluation of Flotation Behavior of Chalcopyrite in the Presence of SIPX and Acetoacetic Acid n-Octyl Ester as a Novel Collector Blend: A Sustainable Approach

The chalcopyrite deposit in Malanjkhand, India, is the largest copper ore producer in the country. However, its flotation performance has room for improvement. This study used standard flotation experiments using a mechanical flotation cell using a conventional collecting reagent and a collector blend consisting of xanthate and ester. A three-factor, three-level Box-Behnken design was used to statistically evaluate the experimental design. The obtained data were analyzed using an ANOVA, cubic plots, and response surface methods. The goal was to evaluate the effects and interactions of three key process parameters in chalcopyrite flotation: the dosages of sodium silicate (depressant), sodium isopropyl xanthate (collector), and acetoacetic acid n-Octyl ester (co-collector/modifier). The results implied that introducing acetoacetic acid n-Octyl ester along with minor tweaks in the dosages of sodium isopropyl xanthate helped increase copper grades by at least 15%, with good recovery percentiles. Among the three parameters tested, the copper’s grade and recovery were considerably positively influenced by the AoE dosage in the collector blend. Employing 0.006 kg/t sodium silicate and 0.0065 kg/t sodium isopropyl xanthate with 0.005 kg/t of acetoacetic acid n-Octyl ester, an optimum copper recovery of 88.87% could be achieved. However, with a sodium silicate dosage of 0.0048 kg/t, a SIPX dosage of 0.008 kg/t, and an AoE dosage of 0.005 kg/t, optimized copper grade (1.55%) could be achieved, which is a 78.1% increase from the feed sample grade. To validate the expected results, verification experiments were carried out, and the experimental findings were found to be on at par with the statistical model predictions. Furthermore, the calculated SPI value of 0.0000147cap Kg−1 for a global index per resident lies between 0 and 1.

The bubble size produced in a pilot HydroFloat® cell and its effects on flotation

Unlike a traditional mechanical flotation cell, Eriez’s HydroFloat® is a fluidized-bed flotation device that can recover much coarser and less liberated particles. This is a new flotation machine where the effects of parameters such as bubble size are yet to be established. To address this problem, JKMRC has built a pilot HydroFloat® rig which it deployed to a copper–gold plant in New South Wales, Australia. Tests were performed at a range of operating conditions and bubble size images were collected and analysed using a novel newly created bubble size measurement method. In conventional flotation, a finer bubble size increases flotation rates because it increases the probability of bubble-particle collision and attachment. In this pilot HydroFloat® test program, however, flotation performance was optimal at an intermediate bubble size. Using the comprehensive test program data, the operating parameters that significantly affect bubble size were established, and an empirical model to predict bubble size was developed.

Selective aggregation of hematite from quartz using charged polyacrylamides: In-situ sizing

Recovering fine valuable material has been a significant challenge in minerals processing. This primarily stems from insufficient collision opportunities between fine particles and bubbles, specifically when utilising traditional recovery methods such as froth flotation. This research endeavours to address this challenge by exploring the use of various commercially available, high molecular weight polymers- specifically polyacrylamide (PAM)- to selectively aggregate hematite from quartz. Investigation of the conditions in which selective aggregation of hematite over quartz occurs, with the goal to achieve aggregate sizes of between 20 and 150 μm, were undertaken. Targeting this size range ensure that conditions are optimised for future use in conventional mechanical flotation cells as an efficient mineral recovery method. The study investigates the selectivity of charged PAM towards hematite and quartz at pH 10, using adsorption studies. Anionic PAM demonstrates a preference for hematite, with a range of charge density studies, highlighting stronger adsorption capacity with lower charge density polymers. Using BlazeMetrics probe technology for in-situ sizing and imaging, it was observed that conditioning 50–300 g APAM per t of hematite resulted in aggregates in the range of 30–230 μm after 5 min. Interestingly, the charge density of APAM does not markedly affect the size of the hematite aggregates, although altering the charge density of the polymer impacts the selectivity towards quartz. Additionally, cationic PAM results in the simultaneous aggregation of both hematite and quartz, not demonstrating selectivity. To mitigate heterocoagulation between minerals, a common dispersant, sodium hexametaphosphate (SHMP), was employed, which notably prevents quartz aggregation. Separation of aggregated hematite from quartz by sedimentation was only slightly effective with the majority of quartz settling with the hematite. Adding up to 1000 g of dispersant per t of hematite reduced the amount of quartz in the sediment bed by 23 %. The dispersant increased the magnitude of the negative zeta potential of the two minerals, particularly hematite, lowering heterocoagulation and improving effectiveness of hematite flocculation.

Exploring the impact of thiol collectors system on copper sulfide flotation through machine learning-driven modeling

Collector selection is a critical step in flotation, as it has a direct impact on product quality, flotation recovery, and selectivity. Collectors can consist of different components, and their effectiveness can vary depending on the type of ore being processed. The general practice in both literature and in industry is to use a mixture of collectors rather than a single collector. However, the use of a collector mixture introduces several complex issues. It is challenging to determine the specific effects of each collector on different minerals, as well as to understand the synergistic effects of mixed collectors in flotation. This study presents a novel investigation focusing on the impact of blends of NAX, AEROPHINE® 3422, and AERO® MX 5149, in varying dosages and combinations, on the flotation performance of Kupferschiefer copper ore. Kinetics flotation tests were conducted using a mechanical flotation cell with various combinations and dosages of listed collectors. For this investigation, different predictive models such as machine-learning (ML) and conventional regression analyses were developed. For model construction, a database including the results of comprehensive experimental results was constructed. The best performing model was selected considering statistical performance indicators and their performance on unseen data. A sensitivity analysis was conducted on the model to justify contributions of collectors on the copper recovery and grade. The results showed that the ML-based models provide compatible results with the expert opinions and have higher statistical performance than conventional modelling tools. According to the experimental results and models’ findings, it has shown that AEROPHINE® 3422 (a blend of isopropyl ethyl thionocarbamate and dithiophosphinate) was the most influential collector for the copper recovery. In addition, two ternary graphs were generated from the modeled data to formulate mixtures for different grades and recovery priorities.

ImhoflotTM Flotation Cell Performance in Mini-Pilot and Industrial Scales on the Acacia Copper Ore

The present work investigates a comparative study between mechanical and ImhoflotTM cells on a mini-pilot scale and the applicability of one self-aspirated H-16 cell (hybrid ImhoflotTM cell) on an industrial scale on-site. The VM-04 cell (vertical feed to the separator vessel with 400 mm diameter) was fabricated, developed, and examined. The copper flotation experiments were conducted under similar volumetric conditions for both the ImhoflotTM and mechanical flotation cells keeping the rest of the parameters constant. Further, one H-16 cell was positioned at four different stages in the Gökirmak copper flotation circuit of the Acacia (Türkiye) copper beneficiation plant, i.e., at (i) pre-rougher flotation, (ii) rougher concentrate, (iii) cleaner-scavenger tailing, and (iv) first cleaning concentrate aiming at enhancing the flotation circuit capacity through flash flotation in the rougher stage, reducing copper grade in the final tailing, and increasing cleaning throughput, respectively. Comparative copper flotation tests showed that ultimate recoveries using the ImhoflotTM and mechanically agitated conventional cells were 94% and 74%, respectively. The industrial scale test results indicated that locating one pneumatic H-16 cell with the duty of pre-floating (also known as flash flotation) led to the enrichment ratio and recovery of 4.84 and 89%, respectively. Positioning the H-16 cell at the cleaner-scavenger tailings could diminish the copper tailings grade from 0.43% to 0.31%. Further, a relatively greater enrichment ratio and copper recovery were obtained using only one ImhoflotTM cell (1.76 and 64%) in comparison with employing four existing mechanical cells (50 m3, each cell) in series (1.45 and 60%) at the first cleaner stage.

Research on resource comprehensive utilization of granite-type sulfide mine tailings

In order to recover and utilize mica and quartz from the tailings of a granite-type sulfide ore in Jiangxi Province, the technique of separating mica and quartz from the tailings by flotation without acid was investigated. Pyrite flotation was performed on a 500 g tailing sample to remove pyrite. And the middlings were acquired by desliming of the unfloated products. Finally mica and quartz was separated from the middlings in the mechanical flotation cell. Under conditions of pH=10.3 with a pulp concentration of 35% and a collector concentration of 180 g/t, a yield of 12.89% mica and 42.73% quartz was obtained, with silica grades as high as 71.50% in the quartz. The mica and quartz products can be used in construction ceramics and construction sand, respectively. It is believed that the outcomes of this work could provide ideas for comprehensive utilization of sulfide tailings.

Effects of operating parameters on residence time distribution in a REFLUX flotation cell

Residence time distribution (RTD) is a critical parameter in design and optimization of flotation processes and machines. RTD measurements provide valuable indication into the distribution of residence times experienced by particulates (e.g., particles, oil droplets) within the system, enabling the identification of flow regimes and potential issues such as short-circuiting, dead zones or inadequate mixing. While previous studies in the literature have generally focused on RTD measurements in mechanical flotation cells, there are limited experimental studies available for pneumatic flotation cells. In this study, RTD measurements were performed to characterize the type of flow regime in the REFLUXTM Flotation Cell (RFC), and to investigate the impacts of operational parameters, including bias, feed flux, and gas flux, using a laboratory-scale RFC-100. An impulse-response methodology was employed with a KCl solution used as a tracer in a two-phase (liquid–gas) system. Large and Small Tanks in Series (LSTS), N-mixer in Series, and Perfect Mixer models were applied to a database created by experimental results. The results revealed that the fluid behavior in RFC-100 approached a plug-flow pattern rather than perfect mixing in the two-phase (liquid–gas) system. Furthermore, an increase in bias resulted in a decrease in mean residence time (MRT), and the tracer concentration inside the cell could be adjusted by varying the gas flux under the same feed flux.

Ultrafine Particle Flotation in a Concept Flotation Cell Combining Turbulent Mixing Zone and Deep Froth Fractionation with a Special Focus on the Property Vector of Particles

Froth flotation faces increasing challenges in separating particles as those become finer and more complex, thus reducing the efficiency of the separation process. A lab flotation apparatus has been designed combining the advantages of agitator-type froth flotation for high turbulences and column flotation with a deep froth zone for a fractionating effect, also enabling a study on the effect of different particle property vectors. A model system of ultrafine (<10 µm) particles was used for flotation to study how the separation process is influenced by the ultrafine property vectors of shape and wettability. To evaluate the new apparatus, flotation tests were carried out in a benchmark mechanical flotation cell under comparable conditions. Higher wettabilities result in higher recoveries, but the results show that optimum levels of hydrophobicity vary for different particle shapes. Different behaviours are observed for differently shaped particles, depending on their wettability state. The entrainment of unwanted gangue is reduced with increasing froth depth. While higher recoveries are obtained for the benchmark cell, the newly developed apparatus produces concentrates with higher grades. Our findings contribute to ultrafine flotation techniques and especially our understanding of the complex effect of particle shape in combination with the other property vectors.

Effect of nanobubbles on flotation of El-Maghara coal

ABSTRACT To extensively explore the advantage of using nanobubbles in the El-Maghara coal flotation process, the effect of nanobubbles on both column and mechanical flotation was investigated under different operating parameters such as diesel oil collector dosage, MIBC frother concentration, superficial feed velocity, superficial air velocity, and superficial wash water velocity in column flotation; besides the slurry flow rate through nanobubbles generator into a 25-liter mechanical flotation cell. The representative coal flotation feed acquired from the El-Maghara deposit located in Sinai, Egypt with chemical characterization using proximate analysis containing 25.27% mineral matter forming ash during coal combustion and with particle size distribution measurement using laser particle size analyzer is 57 µm d90. Also, the flotation kinetic experiments were done to show the influence of nanobubbles on the flotation time required to obtain high-quality coal products with high combustible recovery. Nanobubbles enhanced the flotation performance and kinetics by up to 24% combustible recovery based on the operation parameters reducing flotation time from 4 to 2.25 min for 80% combustible recovery.

Improved Separation between Recycled Anode and Cathode Materials from Li-Ion Batteries Using Coarse Flake Particle Flotation

Separation between two recycled electrode active materials from spent Li-ion batteries by a conventional froth flotation method has been challenging due to similarity in their surface hydrophobicity. In this study, a new coarse flake particle flotation technology has been developed to separate the electrode active materials from Li-ion batteries. The new process separates the recycled electrode flake particles effectively at a size range of 212–850 μm by taking advantage of a significant difference in densities between the anode flake materials and cathode flake materials. At a feed size of 212 μm or less, a fraction of recycled cathode particles is floated in the froth layers resulting in a loss of cathode materials in the sink product. At a feed size of 850 μm or above, a small fraction of anode flakes becomes non-floatable, resulting in a decrease in the grade of cathode materials in the sink product. The mechanism has been investigated by induction time measurements, bubble–flake detachment, contact angle measurements, and force analysis. The anode flakes are more hydrophobic than cathode flakes, which is consistent with the result obtained from induction time measurements. A force analysis reveals that the critical size for electrode flake particles being attached to air bubbles varies with advancing contact angle and density. Maintaining a desirable feed size is essential to achieve an optimum separation performance. In this regard, a flotation column is superior to mechanical flotation cells in minimizing size reduction during the flotation process. Lab-scale column flotation trials showed that a good separation between anode and cathode flake particles has been achieved by column flotation with 98–99% purity of cathode flake materials in the sink product at a recovery rate of 96–99%. The present study demonstrates a new process in separating two electrode flake materials from spent Li-ion batteries.

The surface energy and surface charge of microbubbles generated by frother surfactants

Microbubbles (MBs) in froth flotation have the important function of facilitating the collision and attachment between air bubbles and hydrophobic materials and subsequently recovering the hydrophobic materials. However, whether MBs can be generated in a flotation cell by adding frother surfactants is unknown. This study was designed to determine whether the two widely used frothers, methyl isobutylcarbinol (MIBC), representing alcohol frothers, and Dowfroth 250 (DF250), representing polyglycol ether frothers, could help generate MBs in a mechanical flotation cell. The underpinning air/water interfacial properties were also studied in the presence of the two frothers. The real time bubble size measurement demonstrated that MBs could be generated in the mechanical flotation cell in the presence of MIBC or DF250, and DF250 produced more and smaller MBs than MIBC. Air/water interfacial tension and microbubble zeta potential measurements indicated that the generation of MBs by MIBC and DF250 was primarily controlled by their ability in reducing surface tension. While DF250 formed premicellar aggregates at air/water interfaces and reduced surface tension significantly, MIBC only formed monolayers at air/water interfaces and reduced surface tension slightly. However, the slower adsorption of DF250 at air/water interfaces inhibited the generation of MBs to some extent. Compared with surface tension, surface charge played a secondary role in generating MBs. The adsorption of MIBC reduced the magnitude of surface charge of MBs, thus inhibiting the generation of MBs, while the adsorption of DF250 increased the magnitude of surface charge of MBs, enhancing the generation of MBs. The different behaviours of MIBC and DF250 in modifying interfacial properties and forming MBs were attributed to their unique structures. DF250 possesses a larger hydrophilic head and a longer hydrophobic chain than MIBC, and thus has a stronger ability to assist with the generation of MBs.

A Review on Froth Washing in Flotation

In the attempt to process lower-grade ores, mineral flotation has taken centre stage as the preferred recovery route. However, in many instances, the froth product does not have a high grade due to the entrainment of gangue minerals. Industry has solved this challenge by introducing froth washing mechanisms. Clean wash water is introduced into or on top of the froth to reduce the amount of entrained gangue in the final concentrate. This article reviews froth-washing systems in detail and highlights the advantages and disadvantages of each wash-water delivery mechanism. Comments on industrial uptake are provided. The indications are that froth washing improves the grade of the concentrate and influences froth stability and mobility. Other researchers have reported an improvement in recovery—especially of coarse particles—with wash water being added, while others have reported a reduction in recovery, especially with composite particles. Froth washing is generally applied in mechanical flotation cells by washing at the lip. In column flotation cells and Jameson cells, wash water is added to the entire froth surface. The literature also indicates that the wash-water rate, wash-water quality, type of wash-water delivery/ distribution mechanism and the area covered by wash water are critical parameters that dictate the efficacy of the washing system. Further research is necessary on the impact of wash-water quality on the froth phase sub-processes including froth rheology.

Multi-phase CFD modelling of Slurry Column Flotation – Validation of both Hydrodynamic and Kinetic Parameters

Column flotation is widely used for the beneficiation of fines in the mineral processing industry. The kinetics in the column flotation is mainly influenced by the hydrodynamics and the flotation sub-processes such as bubble particle collision, attachment, and detachment. Computational fluid dynamics (CFD) is a popular tool that can be used to evaluate flotation kinetics. However, most of the published works on the flotation kinetics with CFD were limited to mechanical flotation cells. In the current investigation, a CFD model is applied to explore both the hydrodynamics and kinetics of the column flotation. CFD simulations are performed for two-phase systems of column flotation on the Eulerian-Eulerian framework. The standard k-ε turbulence model is utilized in this methodology along with the drag, lift, and virtual mass forces. The hydrodynamic parameters such as axial, and radial gas holdup and its distribution were predicted from the CFD simulations and validated with Electrical Resistance Tomography (ERT) experimental results. In the kinetic study, the flotation kinetic sub-processes, such as bubble-particle collision, adhesion, and detachment were also predicted. The error between the ERT experimental and CFD simulations was found to be 2.71 and 6.75%, respectively at 0.006 and 0.018 m/s superficial air velocities. The effect of particle contact angle and particle size on the kinetic constants of attachment (

Influence of hydrodynamic variables on scaling up of mechanical flotation cells

Flotation performance is influenced by many hydrodynamic variables, such as impeller speed, airflow rate, and cell geometry. These variables’ effects and interactions remain unsatisfactorily explored, especially concerning scaling-up procedures. As an innovative approach, this study considered factorial-designed experiments to explore the effects of hydrodynamic factors (impeller tip speed and superficial gas velocity) on scaling up the Outotec GTK LabCell™ mechanical flotation machine cells, common equipment used as a benchmark for many industrial pre-feasibility studies. Therefore, the influence of hydrodynamic variables and their interactions on flotation performance was evaluated in two cells (2 L and 7.5 L). The evaluation was based on the flotation rate constant “k” calculated by first- and second-order equations. Analysis of the particle size distribution indicated that the performance of the two cells was different, as shown by the finer concentrate for the 2-L cell compared to the 7.5-L cell. The outcomes demonstrated that symmetrical design in the geometry of mechanical flotation cells would lead to an accurate scaling up based on the metallurgical responses. Otherwise, the scaling procedure could only be accurate under some specific conditions. As a criterion, the results showed that using k, the scaling-up process between these two GTK LabCell™ mechanical flotation machine cells (2 L and 7.5 L) would be possible only under a specific superficial gas velocity (0.14 cm/s) apart from the impeller tip speed (R2 = 1). These results could potentially be key for the future design and development of mechanical flotation cells.

The Use of Radioactive Tracers to Detect and Correct Feed Flowrate Imbalances in Parallel Flotation Banks

This work presents the application of radioactive tracers to detect and correct feed flowrate imbalances in parallel rougher flotation banks. Several surveys were conducted at Minera Los Pelambres concentrator, in banks consisting of 250 m3 mechanical flotation cells. The feed pulp distribution was estimated from the mean residence times, which were obtained from residence time distribution measurements. The tracer was injected in the feed distributor and the inlet and outlet tracer signals of cells 1 and 2 were measured by on-stream sensors. The baseline condition for the pulp distribution was defined by the valve settings in the feed distributor, which led to an unbalanced condition for two parallel rougher banks, with 34% of the pulp being fed to bank A and 66% to bank B. New valve configurations were evaluated, with a fraction of the feed being directed to the rougher bank C, which was not initially fed from the same distributor. The feed distribution was finally balanced with 49% of the pulp being fed to bank A versus 51% to bank B. Thus, the radioactive traces proved to be a powerful tool to industrially detect and improve feed distributions in parallel flotation circuits.

Improvement of dynamic foam stability with low-frequency acoustic sound

Exposing the froth phase of a flotation system to low-frequency acoustic sound was reported to improve the process efficiency, which was thought to be due to the improvement in the froth stability. However, no direct evidence of the stabilization effect of sound on froths or foams is available to date. The present work aims to resolve this issue by experimentally studying the effect of low-frequency acoustic sound on the stability of a foam, the two-phase counterpart of flotation froth, across a wide range of experimental conditions. Three different setups consisting of a flotation column or a bottom-driven mechanical flotation cell, with the foam being exposed to sound from above or below, were tested. The equilibrium height of the foam with a given flow rate of air supply was measured at steady state using the Bikerman’s method. The equilibrium foam height was found to increase within certain ranges of sound frequencies and amplitudes, and at various surfactant concentrations (3–50 ppm) and superficial gas velocities (0.3–2.0 cm·s−1). An increase in sound amplitude or superficial gas velocities was also found to broaden the range of sound frequency that led to the stabilization effect. These findings were largely common for the three different setups tested, suggesting that this is a versatile method for improving the stability of foams. A strong correlation was also found between the stabilization of foam demonstrated in the present work and the stabilization of froth reported in a previous study, implying that the stabilization mechanisms could be similar.

Mechanical Flotation of Mineral Particles with an Underwater Speaker

ABSTRACT This paper aims to demonstrate a safe, non-chemical approach for improving the efficiency of froth flotation. Laboratory scale flotation tests for quartz particles of different sizes (< 20 µm, 20–38 µm, 38–75 µm, 75–106 µm, 106–150 µm, 150–212 µm) with an ether amine collector at different dosages were conducted in batch mode by using a bottom-driven mechanical flotation cell. An underwater loudspeaker was placed in the flotation pulp phase. The solids concentrations tested were 5% and 20% by weight. The results showed that acoustic sound (at 375 Hz and 77 decibels) increased the flotation recovery by at least 6% over a broad particle size range (i.e. 20–212 micron). The results also suggested applying acoustic sound in a flotation system can improve flotation recovery to a larger extent at a lower reagent dosage. An advantage of having the loudspeaker immersed in the pulp phase rather than in air above the flotation cell was the substantially reduced noise level. The present study provides a potential approach for improving flotation performance and reducing the chemical reagent consumption in flotation cells.

Technological assessments on recent developments in fine and coarse particle flotation systems

• 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.

Combined Column and Mechanical Flotation Cell Process for the Beneficiation of Sanshandao Gold Ore.

Semi-industrial tests were conducted to investigate the feasibility and efficiency of a combined column and mechanical flotation cell process for the beneficiation of Sanshandao low-grade gold ore. The results showed that the performance of the combined flotation process of the cyclonic-static microbubble flotation column (FCSMC) and mechanical flotation cells was superior to that of the mechanical flotation cell, while the flowsheet was simplified. FCSMC is efficient when used on fine particles, whereas a mechanical flotation cell is effective for coarse particles. Thus, the combined flotation process exhibited a better separation performance by employing the strengths of both methods. The use of the combined FCSMC and cell flotation process showed promising results for a producing grade of 48.24 g/t gold with 96.13% recovery. The combined column and cell flotation process introduces a new approach for the separation of low-grade gold ore.

Influence of surface dissolution on reagents’ adsorption on low-grade phosphate ore and its flotation selectivity

A preliminary study was conducted on the Hallimond tube to find routes for the direct flotation of fluorapatite. Carboxymethylcellulose-sodium oleate and sodium alginate-sodium oleate were the most promising depressant-collector combinations. Apatite recovery exceeded 95%. Conversely, replication of these findings in the mechanical flotation cell proved to be different. The results show a flotation of the calcite, while the fluorapatite remains in the tailings. Grades of 27.63% P2O5 with a recovery of 69.9% and 28.22% P2O5 with a recovery of 73.93% were obtained in the non-floated fraction using 1500 g/t of sodium oleate and 25 g/t of sodium alginate and carboxymethylcellulose as depressants, respectively.The effects of metal ions on the flotation behavior of fluorapatite, calcite, and quartz were investigated through micro-flotation tests and bench-scale flotation experiments. The findings were further elucidated by dissolution study, zeta potential measurements, and FTIR analyses. The results demonstrated that pulp water containing large amounts of Ca2+, Mg2+, and Fe3+ directly influences the performance of apatite flotation. Fluorapatite recovery substantially dropped from 97.27% in deionized water, reaching values below 11.11% at alkaline pH. These ionic species interfere in the interfacial processes and perturb selective adsorption. Ca2+ ions favor the precipitation of CaCO3, hence forms a coating on the apatite surface, rendering it unavailable for NaOL chemisorption. Ca2+, Mg2+, and Fe3+ complex with the reagents and the precipitates adsorb onto the minerals’ surfaces, impairing their floatability. Also, their presence activates the quartz surface, increasing its recovery. Zeta potential curves overlap, implying a similar build-up of negative charge on the three mineral surfaces. The most intense peaks in FTIR spectra indicated more adsorption, suggesting that the detrimental species Ca2+, Mg2+, Fe3+ must be involved in adsorption mechanisms and explain flotation trend change.