Search Results (27)

The increasing demand for critical raw materials such as copper and cobalt highlights the need for efficient beneficiation of low-grade ores. This study investigates a copper–cobalt sulfide ore (0.99% Cu, 0.028% Co) using froth flotation to produce high-grade concentrates. Various types of surfactants are applied in different ways, each serving an essential function such as acting as collectors, frothers, froth stabilizers, depressants, activators, pH modifiers, and more. A series of flotation tests employing different collectors (SIPX, PBX, AERO, DF 507B) and process conditions was conducted to optimize recovery and selectivity. Methyl isobutyl carbinol (MIBC) was consistently used as the foaming agent, and 700 g/L was used as the slurry density at 25 °C. Dosages of 30 and 100 g/t¹ were used in all tests. Notably, adjusting the pH to ~4 using HCl significantly improved cobalt concentrate separation. The optimized flotation conditions yielded concentrates with over 15% Cu and metal recoveries exceeding 80%. Mineralogical characterization confirmed the selective enrichment of target metals in the concentrate. The results demonstrate the potential of this beneficiation approach to contribute to the European Union’s supply of critical raw materials. Full article

The prevention of bubble coalescence is essential in various industrial processes, such as mineral flotation, where the stability of air–liquid interfaces significantly affects performance. The combined influence of multiple physicochemical parameters on bubble coalescence remains insufficiently understood, particularly under conditions relevant to flotation. This study explores the key factors that influence the inhibition of bubble coalescence in aqueous solutions containing methyl isobutyl carbinol (MIBC), providing a systematic comparative analysis to assess the effect of each variable on coalescence inhibition. An experimental method was employed in which two air bubbles were formed from identical capillaries and brought into contact either head-to-head or side-by-side, then held until coalescence occurred. This setup allows for reliable measurements of coalescence time with minimal variability regarding the conditions under which the bubbles interact. The study examined the effects of several factors: temperature, pH, salt concentration and type, bubble approach speed, contact area, and contact configuration. The results reveal that coalescence is delayed at lower temperatures, alkaline pH conditions, high salt concentrations, and larger interfacial contact areas between bubbles. Within the range studied, the influence of approach speed was found to be insignificant. These findings provide valuable insights into the fundamental mechanisms governing bubble coalescence and offer practical guidance for optimizing industrial processes that rely on the controlled stabilization of air–liquid interfaces. By understanding and manipulating the factors that inhibit coalescence, it is possible to design more efficient and sustainable mineral flotation systems, thereby reducing environmental impact and conserving water resources. Full article

Flotation was investigated to treat incineration fly ash with diesel, kerosene, TX-100, or SDS as a collector and methyl isobutyl carbinol (MIBC) or 2-Octyl alcohol as a frother. Fly ash was separated into light and residual materials. Comparison of yield, carbon and sulfur removal showed that kerosene and MIBC showed the best performance. The results revealed that flotation was a method that could simultaneously achieve the removal of organics and S-containing compounds. Specifically, approximately 7.63–9.45% of the total mass was collected as light material, which was enriched with organic carbon. Contents of organic carbon reached 14.35 wt%–14.56 wt% in the light materials from those of 2.74 wt%–3.52 wt% in the original fly ash. Elemental analysis further proved that sulfur was also accumulated in light material. Approximately 78.84–81.69% of the organic carbon and 80.47–82.66% of the sulfur were removed. Decarbonization was primarily achieved through the flotation of organic materials, while desulfurization resulted from both flotation and the dissolution of soluble salts. Furthermore, the contents of the chloride and heavy metals in the residual fly ash also decreased. Particle size analysis showed that flotation was effective in the removal of smaller particles, and those particles were also rich in heavy metals. Overall, by selecting the right collector and frother, flotation was also able to reduce the leaching toxicity of heavy metals. The residual fly ash was safe for further disposal. Organic carbon, sulfur and heavy metals were accumulated in the light materials, which accounted for less than 10% of the original mass. The portion of fly ash needing further treatment was therefore greatly reduced. Full article

The aim of this study is to explore the feasibility of using flotation wastewater from copper–porphyry ore processing to synthesize a gel that serves as a precursor for a polymer nanocomposite used in supercapacitor electrode fabrication. These wastewaters—characterized by high acidity and elevated concentrations of metal cations (Cu, Ni, Zn, Fe), sulfates, and organic reagents such as xanthates, oil (20 g/t ore), flotation frother (methyl isobutyl carbinol), and pyrite depressant (CaO, 500–1000 g/t), along with residues from molybdenum flotation (sulfuric acid, sodium hydrosulfide, and kerosene)—are byproducts of copper–porphyry gold-bearing ore beneficiation. The reduction of Ni powder in the wastewater induces the degradation and formation of a gel that captures both residual metal ions and organic compounds—particularly xanthates—which play a crucial role in the subsequent steps. The resulting gel is incorporated during the oxidative polymerization of aniline, forming a nanocomposite with a polyaniline matrix and embedded xanthate-based compounds. An asymmetric supercapacitor was assembled using the synthesized material as the cathodic electrode. Electrochemical tests revealed remarkable capacitance and cycling stability, demonstrating the potential of this novel approach both for the valorization of industrial waste streams and for enhancing the performance of energy storage devices. Full article

Electronic waste stream grows day by day; printed circuit boards are a kind of solid waste that accounts for 6% of electronic waste. When these are discarded, they can cause soil, water, and air contamination; however, if recycled, these can be considered as a secondary source of metals. Physical comminution of printed circuit boards generates particles with sizes smaller than 250 µm, which are typically not included in the recycling process because they are considered as dust and unvaluable; nevertheless, precious and base metals can be found in these particles. The concentration of metals like silver, among others, from these particles can be achieved by reverse froth flotation in a flotation column followed by magnetic separation of the tails products. A mass balance of the flotation column feed, concentrate, and tails indicates that using a pulp modified with 5 ppm methyl isobutyl carbinol plus 5 g/ton oleic acid (both biodegradable reagents), the concentration of the products improved, resulting in recoveries of 86.13 and 13.87% in the concentrate and tails zones, respectively, with a grade of 74.4% in the tails flow. Magnetic separation of the tails product increases slightly the concentration of silver, reaching a silver grade of 74.5%, a recovery amount similar to those obtained employing complex and environmentally unfriendly processes. Full article

Steelmaking processes inevitably generate large amounts of byproducts, including slags, specks of dust, etc., and their treatment has been a critical issue for the steelmaking industry. Kish graphite is a valuable substance existing in steelmaking byproducts, and the recovery of Kish graphite has attracted more attention in recent years. The purpose of this study was to use a multi-stage froth flotation process for the beneficiation of Kish graphite and to investigate the influence of flotation conditions on the mass distribution of graphite and impurities. The results showed that the dust D2 contained ~34 wt.% of graphite and thus had the highest potential for the recovery of Kish graphite. The dosages of frother (methyl isobutyl carbinol, MIBC) at 0.005 kg/t and collector (kerosene) at 1 kg/t were optimal for the flotation of Kish graphite. After three-stage froth flotation, the graphite content of the concentrate was progressively increased to 84.09 wt.%, and the entire recovery rate was 93.05%. During the multi-stage froth flotation process, most of the impurities were separated in stage I, but the Fe-containing impurities were mainly separated in stage II. Some Ca²⁺, Na⁺, and K⁺ were leached out, and there were barely any heavy metals in the liquid phases. Full article

The molecular structure of the liquid–vapor interfaces of aqueous solutions of alkali metal halides and methyl isobutyl carbinol (MIBC, (CH₃)₂CHCH₂COCH₃) is determined by using molecular dynamics simulations with polarizable force fields for the first time. The salts are chlorides, and iodides, some of which are found in raw and partially desalinated seawater increasingly used in flotation operations in regions affected by severe and prolonged drought. The density profiles at the interfaces show that all ions prefer the interface; however, with MIBC, non-polarizable ions, generally small ones, are increasingly pushed into the liquid bulk. A few ions of comparatively less ionic NaCl than KCl and CsCl, persist at the interface, consistent with spectroscopy observations. On the other hand, strongly polarizable ions such as I⁻ always share the interface with MIBC. In the presence of chlorides, the frother chains at the interface stretch slightly more toward vapor than in freshwater; however, in the presence of iodides, the chains stretch so much that they become orthogonal to the interface, giving rise to a well-packed monolayer, which is the most effective configuration. The dominant water configurations at the interface are double donor and single donor, with hydrogen atoms pointing toward the liquid, consistent with studies with sum-frequency generation experiments and extensive ab initio simulations. This picture changes radically in the presence of MIBC and salts. Depending on the halide and MIBC concentration, the different molecular configurations at the interface lead to very different surface tensions. The structure and properties of these new salt-rich interfaces and their impact on the location and arrangement of frother molecules should serve the flotation practitioner, especially in the search for the best frother and dosing in poor-quality water. Full article

In recent years, most of the studies have been adapted to determine the optimum conditions for the flotation of very fine minerals. In this context, besides parameters such as particle size, morphology, and pH, the effects of frother type and its concentration present a very significant role in optimizing the flotation conditions. Therefore, the effects of froth stability during flotation can be considered one of the most important issues. Considering that knowledge in mind, in this study, the foamability and froth decay rate of six frothers (PPG200, PPG400, PPG600, BTEG, BTPG, and BDPG) having different molecular weights but similar polyglycol structures were investigated. In addition, methyl isobutyl carbinol (MIBC) which is a well-known frother type in the industry was also used as a reference. Additionally, a series of tests were also performed in the presence of collectors (Dodecylamine hydrochloride, DAH, and sodium oleate, NaOL) + frother mixtures to mimic the flotation conditions. The results of these tests indicated that the bubble size became finer at even low concentrations of PPG600 and PPG400 frothers. Following that, a significant decrease in bubble size was also found for the collector + frother mixtures system regardless of the concentration of the frothers. Full article

The present study investigates the optimization and advanced simulation of the flotation process of coarse particles (–425 + 106) using micro-nanobubbles (MNBs). For this purpose, flotation experiments in the presence and absence of MNBs were performed on coarse quartz particles, and the results were statistically analyzed. Methyl isobutyl carbinol (MIBC) was employed as a frother for generating MNBs through hydrodynamic cavitation. The significance of the operating variables, including impeller speed, air flow rate, together with the bubble size, and particle size on the flotation recovery was assessed using historical data (HD) design and analysis of variance (ANOVA). The correlation between the flotation parameters and process response in the presence and absence of MNBs was modeled using hybrid convolutional neural networks (CNNs) and recurrent neural networks (RNNs) as the deep learning (DL) frameworks to automatically extract features from input data using a CNN as the base layer. The ANOVA results indicated that all variables affect process responses statistically and meaningfully. Significant interactions were found between air flow rate and particle size as well as impeller speed and MNB size. It was found that a CNN-RNN model could finally be used to model the process based on the intelligent simulation results. Based on Pearson correlation coefficients (PCCs), it was evident that particle size had a strong linear relationship with recovery. However, Shapley additive explanations (SHAP) was considerably more accurate in predicting relationships than Pearson correlations, even though the model outputs agreed well. Full article

Can the DLVO theory predict the foamability of flotation frothers as MIBC (methyl isobutyl carbinol)? The flotation froth is a multi-bubble system, in which the bubbles collide, thus either coalescing or rebounding. This scenario is driven by the hydrodynamic push force, pressing the bubbles towards each other, the electrostatic and van der Waals forces between the bubbles, and the occurrence of the precipitation of the dissolved air between the bubbles. We studied the foamability of 20 ppm MIBC at constant ionic strength I = 7.5 × 10⁻⁴ mol/L at different pH values in the absence and presence of modified silica particles, which were positively charged, thus covering the negatively charged bubbles. Hence, we observed an increase in the foamability with the increase in the pH value until pH = 8.3, beyond which it decreased. The electrostatic repulsion between the bubbles increased with the increase in the pH value, which caused the electrostatic stabilization of the froth and subsequently an increase in the foamability. The presence of the particles covering the bubbles boosted the foamability also due to the steric repulsion between the bubbles. The decrease in the foamability at pH > 8.3 can be explained by the fact that, under such conditions, the solubility of carbon dioxide vanished, thus making the aqueous solution supersaturated with carbon dioxide. This caused the precipitation of the latter and the emergence of microbubbles, which usually make the bubbles coalesce. Of course, our explanation remains a hypothesis. Full article

The separation of graphites and cathode materials from spent lithium-ion batteries (LIBs) is essential to close the loop of material used in LIBs. In this study, the roasting characteristics of the spent LIB materials are carefully analyzed, and the effects of roasting on the surface morphology and elemental chemical states of electrode materials are fully investigated by thermogravimetric analysis, SEM-EDS, and XPS to explore the roasting–flotation enhancement mechanism. Then, froth flotation is utilized to separate the graphites and cathode materials from the spent LIB materials. The optimal roasting temperature is determined by thermogravimetric analysis and the SEM-EDS analysis of the spent LIB materials. The results suggest that the organic binder can be effectively removed from the spent LIB materials at the roasting temperature of 500 °C, and there is almost no loss of graphite. The XPS results indicate that, in the process of roasting, the decomposition products of the organic binder can easily react with valuable metals (Ni, Co, and Mn) to produce corresponding metal fluoride. The flotation results of the spent LIB materials after roasting at the optimal conditions indicate that graphites and cathode materials can be efficiently recovered through roasting–froth flotation. When the dosage of kerosene is 200 g/t and the dosage of methyl isobutyl carbinol (MIBC) is 150 g/t, the cathode materials grade is 91.6% with a recovery of 92.6%, while the graphite grade is 84.6% with a recovery of 82.7%. The roasting–froth flotation method lays the foundation for the subsequent metallurgical process. Full article

Methyl isobutyl carbinol (MIBC) is a high-performance surfactant with unusual interfacial properties much appreciated in industrial applications, particularly in mineral flotation. In this study, the structure of air–liquid interfaces of aqueous solutions of MIBC-NaCl is determined by using molecular dynamics simulations employing polarizable and nonpolarizable force fields. Density profiles at the interfaces and surface tension for a wide range of MIBC concentrations reveal the key role of polarizability in determining the surface solvation of Cl⁻ ions and the expulsion of non-polarizable Na⁺ ions from the interface to the liquid bulk, in agreement with spectroscopic experiments. The orientation of MIBC molecules at the water liquid–vapor interface changes as the concentration of MIBC increases, from parallel to the interface to perpendicular, leading to a well-packed monolayer. Surface tension curves of fresh water and aqueous NaCl solutions in the presence of MIBC intersect at a reproducible surfactant concentration for a wide range of salt concentrations. The simulation results for a 1 M NaCl aqueous solution with polarizable water and ions closely capture the MIBC concentration at the intercept. The increase in surface tension of the aqueous MIBC/NaCl mixture below the concentration of MIBC at the intersection seems to originate in a disturbance of the interfacial hydrogen bonding structure of the surface liquid water caused by Na⁺ ions acting at a distance and not by its presence on the interface. Full article

This paper studies the effect of the type and concentration of selected frothers, the gas flowrate, and the pore size of the porous frit on the bubble sizes (Sauter mean diameter, SMD) of bubbling flow produced in a micro-flotation cell, and the determination of bubble size distribution (BSD) in the presence of the frothers. The commercial frothers polypropylene glycols (PPG 200, 400, and 600), tri propylene glycol (BTPG), triethylene glycol (BTEG), dipropylene glycol (BDPG), and Methyl Isobutyl Carbinol (MIBC) were used in the present investigation. The frother concentration varied from 1 to 1000 ppm. The flow rate varied in the range of 25 to 100 cm³/min. The pore sizes of the frit were selected as 10–16 μm, 16–40 μm, and 40–100 μm. Each frother exhibited its own unique ability in preventing coalescence of the bubbles in the order of BTEG < BDPG < PPG 200 < MIBC < BTPG < PPG 400 < PPG 600. The factorial experiments established that the type of the frother and its concentration have a major effect on the size of the bubbles. The bubbles decreased twice their size when the frother concentration was increased from 1 ppm to 1000 ppm. The pore size of the frit is a significant factor as well. The size of the bubbles can be reduced from about 10% to about 40% by decreasing the pores from 40–100 μm to 10–16 μm but the level of this decrease depends on the type of the frother. The increase of the flowrate from 25 cm³/min to 100 cm³/min produced bubbles smaller by 25% to 50% for the case of BTEG, BDPG, PPG 200, MIBC, BTPG, while a minimum of the bubble sizes was reached for the case of PPG 400 and PPG 600, beyond which the bubbles enlarged their size. The BSD in the presence of PPG 600 varied around 0.3 mm, whereas BTEG gave a wider BSD which indicated that the type of frother affected the bubble production. Our analysis shows that the first group of frothers adsorbs instantly on the bubbles, once they leave the porous frit, thus reaching equilibrium. PPG 400 and PPG 600 adsorb significantly slower on the bubbles, possibly not reaching equilibrium during their resident time. Full article

Considering sustainable mining, the use of seawater in mineral processing to replace conventional water is an attractive alternative, especially in cases where this resource is limited. However, the use of this aqueous medium generates a series of challenges; specifically, in the seawater flotation process, it is necessary to adapt traditional reagents to the aqueous medium or to propose new reagents that achieve better performance and are environmentally friendly. In this research, the technical feasibility of using recycled vegetable oil (RVO) as a collector of copper sulfide minerals in the flotation process using seawater was studied. The study considered the analysis of the metallurgical indexes when different concentrations of collector and foaming reagent were used, considering as collectors the RVO, potassium amyl xanthate (PAX) and mixtures of these, in addition to the methyl isobutyl carbinol (MIBC) as foaming agent. In addition, it was evidenced that the best metallurgical indexes were achieved using 40 g/t of RVO and 15 g/t of MIBC, which corresponded to an enrichment ratio of 6.29, a concentration ratio of 7.01, a copper recovery of 90.06% and a selectivity index with respect to pyrite of 4.03 and with respect to silica of 12.89. Finally, in relation to the study of the RVO and PAX collector mixtures, it was found that a mixture of 60 g/t of RVO and 40 g/t of PAX in the absence of foaming agent presented the best results in terms of copper recovery (98.66%) and the selectivity index with respect to pyrite (2.88) and silica (14.65), improving PAX selectivity and recovery compared to the use of RVO as the only collector. According to these results, it is possible to conclude that the addition of RVO improved the selectivity in the rougher flotation for copper sulfides in seawater. This could be an interesting opportunity for the industry to minimize the costs of the flotation process and generate a lower environmental impact. Full article

This paper investigates the effect of sodium hexametaphosphate (SHMP) depressant/dispersant in the presence of methyl isobutyl carbinol (MIBC) frother and soluble starch (SS) depressant on the flotation kinetics of talc ore. Emphasis is on a comparison between the evaluation of a custom design of experiment (DoE) using the multilinear regression analysis (MRA) and response surface methodology (RSM) approach. Although analysis of variance (ANOVA) is a good first step in the evaluation of the effect of factors on froth flotation processing, it nonetheless only reveals the effects that are the same under all conditions. In the case of SHMP, its effect on separation efficiency is positive; however, if it is used along with SS, the effect is negative. Moreover, if a higher frother dosage is used, the effect of SHMP on separation efficiency is negligible. Full article