Flotation Of Sulfide Minerals Research Articles

Treatment Technology and Research Progress of Residual Xanthate in Mineral Processing Wastewater

Xanthate is the most widely used and effective collector in the flotation of sulfide minerals. However, the residual xanthate in flotation wastewater may cause serious environmental pollution and even human health hazards. At present, a variety of treatment technologies have been developed to degrade xanthate pollutants in wastewater, with the aim of meeting safe discharge standards. This work reviews the research status of xanthate wastewater treatment technologies in recent years. Treatment technologies are evaluated, including coagulation flocculation, adsorption, microbiological, Fenton, ozone oxidation, and photocatalytic methods. The reaction mechanisms and advantages, as well as disadvantages, of the various treatment technologies are summarized. Future research on the treatment of xanthate wastewater should focus on combined methods, which will be conducive to achieving a high efficiency and low cost, with no secondary pollution, and with the aim of generating further original and innovative technologies.

In situ Raman investigation of dissolved constituent and its evolution in pulp during Zn-S selective flotation with two-step pulp regulation

Redox potential (Eh) of the pulp dominates Zn-S selective flotation, and regulating Eh can maximize Zn grade and recovery of Zn rougher concentrates. However, reasons accounting for the beneficial results of Eh regulation in flotation have not been previously elucidated. This study investigated the inherent causes of macro flotation results by inductively coupled plasma optical emission spectrometer (ICP-OES), Raman spectra and X-ray diffraction (XRD) analyses. The ICP-OES data showed that the levels of calcium and sulfur in the pulp increased considerably after lime regulation. The Raman spectra confirmed that calcium polysulfide (CaSn, n = 2–8) was generated and maintained long-term stability in the pulp regulated by lime without Eh regulation. However, under Eh regulation, CaSn only kept momentary existence in the pulp. Polysulfide reacted quickly with the added copper sulfate and formed brown precipitates, whose main component identified by XRD was CuS, leading to the ineffectiveness of copper-activation for Zn flotation. These findings provide a new insight into the role of Eh in sulfide mineral flotation and partially explain the main reasons to hinder the high-efficiency selective separation of sphalerite from pyrrhotite-containing sulfide ores.

Selective flotation of pyrite from serpentine using phytic acid as the depressant

The flotation of sulfide minerals has been always a problem due to the slime coating of serpentine. In this study, phytic acid (PA) was introduced as a selective depressant to eliminate the adverse effect of serpentine on the flotation of pyrite. Micro-flotation tests showed that the flotation performance of pyrite depressed by serpentine could be regained with the addition of PA. In addition to micro-flotation tests, the action mechanism of PA was systemically investigated based on a series of analyses including zeta potential tests, adsorption measurements, turbidity studies and X-ray photoelectron spectroscopy (XPS) analyses. It was found that PA could chemically react with the active Mg sites and then selectively adsorb onto serpentine surface. In this case, the surface potential of serpentine was shifted from positive to negative at pH 9, thus resulting in the transformation of electrostatic interaction between pyrite and serpentine from electrostatic attraction to electrostatic repulsion. Hence, the slime coating of serpentine on pyrite surface was removed and the adsorption amount of potassium butyl xanthate (PBX) onto pyrite surface was regained. In this way, the adverse effect of serpentine on the flotation of pyrite was eliminated.

Electrochemical and XPS investigations on the galvanic interaction between pentlandite and pyrrhotite in collectorless flotation system

Pentlandite and pyrrhotite are ubiquitously symbiotically aggregated with each other, and the galvanic interaction between them inevitably occurs in flotation process. However, there were few detailed researches regarding this galvanic interaction and its effect on the surface oxidation of pentlandite and pyrrhotite that has been reported. In this work, the galvanic interactions and its influence on the surface oxidation and collectorless flotation behaviors of pentlandite and pyrrhotite were systematically researched at pH 8.5. Results of electrochemical measurements showed that pentlandite had a higher OCP value than pyrrhotite, indicating that pentlandite would act as the cathode, while pyrrhotite acted as the anode in the galvanic couple. Compared to the minerals oxidized solely, a more passivated surface was found for both pentlandite and pyrrhotite. ICP-OES and XPS analyses demonstrated that in the presence of pyrrhotite, a thicker iron oxide/hydroxide film was obtained with a decrease in the species of sulfate and nickel oxide/hydroxide on pentlandite surface. For pyrrhotite, within the galvanic interaction, the oxidation and metal dissolution of pyrrhotite was accelerated. However, the hydrogen ion generated in the anodic reaction would hinder the precipitation of iron oxide/hydroxide and sulfate on pyrrhotite surface. Micro-flotation results further confirmed that the galvanic interaction between pentlandite and pyrrhotite significantly affected their collectorless flotation behaviors, which was also affected by the relative content ratio between them. This work systematically studied the galvanic interaction and its role in the surface oxidation in pentlandite/pyrrhotite collectorless flotation system, which could also provide reference for the further study on complex Ni-bearing sulfide minerals flotation.

A molecular analysis on nitrile-based collectors and their application to chalcopyrite flotation

In this research, one of the newest nitrile-based collectors so-called Tecflote-S10, was re-structured to increase its application in the flotation of copper-bearing sulfide minerals. For this purpose, a systematic theoretical study was conducted using a self-consistent periodic density functional theory (DFT) calculation to identify the adsorption properties of several new-designed nitrile-based collectors on the chalcopyrite (100) surface. In the new collector design, the long hydrocarbon chain of the Tecflote-S10 was replaced with a phenyl ring having several functional groups in different positions to address the electron-donating effect on the strength of the adsorption. The electronic properties and reactivity of new-designed collectors were evaluated, and a proper synthesis route was proposed. Collector-surface interaction and adsorption efficiency of new collectors on chalcopyrite surface were investigated using adsorption energy, the Fukui function (FF), and partial density of state (PDOS) analyses. It was found that replacing phenyl ring in the collector structure instead of a long hydrocarbon chain lead to an improvement in the collector adsorption efficiency. Accordingly, all new-designed collectors showed higher adsorption ability on chalcopyrite than the Tecflote-S10. However, collectors with the acronyms Tf(Ph)-3-R5, Tf(Ph)-N-2R1, and Tf(Ph)-N-2R2 with higher adsorption energies compared to others could be potentially used as a proper alternative in chalcopyrite flotation. To verify the results experimentally, futuristic adsorption, wettability, and floatability tests will be examined for this study.

Recovery of valuable elements from pyrite pyrolysis slag using magnetic separation-flotation technique

Pyrite concentrate is a common by-product obtained after Pb and Zn sulfide minerals flotation. Pyrolysis at 600 ∼ 700 °C in an inert atmosphere is an effective way to comprehensively utilize pyrite concentrate. However, the content of Pb and Zn in pyrolysis slag is relatively high, which is not conducive to subsequent utilization. The pyrrhotite in the pyrolysis slag is magnetic, and lead and zinc mainly exist in the form of sulfide, which has good floatability. This inspired us to purify pyrolysis slag by magnetic separation and flotation method. The results show that when the grinding particle size of −0.040 mm accounts for 80.1 %, the content of Pb and Zn in pyrolysis slag decreased to 0.32 % and 0.17 %, respectively, by only using the magnetic separation method. Then the combined method of magnetic separation and flotation is used. Lead and zinc can be reduced to 0.14 % and 0.10 %, while the iron grade increased to 57.32 %. Then pyrrhotite concentrate is oxidized and roasted at 900 °C to obtain a product that meets the first grade of pyrite cinder. At the same time, the phase, coexistence relationship, and dissociation degree of iron, lead, and zinc minerals in the samples were characterized by MLA and chemical methods to analyze the transformation mechanism of pyrolysis slag in the process of magnetic separation and flotation. The results of this study provide an economical and green process for the comprehensive utilization of pyrite concentrate.

Improved flotation separation of sulfide minerals by synthesized surfactant based on para-position methyl effect

Flotation, as one of the greatest technologies in the 21st century, enables humans to utilize the mineral resources on a large scale. The key to a successful flotation separation is the surfactants with unique selectivity towards different minerals. A flotation surfactant has both chelating side and hydrophobic side. In the past decades, the selectivity of the flotation surfactants has been always attributed to the chelating side. Inspired by an interesting ‘magic methyl effect’ in the field of pharmaceutical chemistry that introducing a methyl group on the hydrophobic side can significantly improve the medicine’s selectivity. In this work, based on an archetype collector sodium benzenesulfinate (SBS) which bears inconspicuous selectivity towards galena and pyrite, a methyl group was introduced to synthesize a novel collector sodium p-toluenesulfinate (SPTS). The flotation tests confirmed that SPTS has much better selectivity than SBS and ethyl xanthate (EX), a commonly used collector for galena flotation against pyrite, which was supported by the results of FTIR, XPS, adsorption capacity and contact angle measurements. DFT calculations revealed that the selectivity of SPTS stems from its desolvation effect and the difference in hydration layers of galena and pyrite. The SPTS can destroy the S···H hydrogen-bonded water molecules via desolvation effect and adsorb on galena surface to make it hydrophobic, but cannot repel the FeO chemically bonded water molecules on pyrite surface. However, the SBS or EX can realize co-adsorption with the water molecules on both minerals with no selectivity. This study provided a new strategy for designing the selective surfactants for successful sulfide minerals flotation.

Oxidation-reduction effects in the flotation of copper sulfide minerals and molybdenite – A proof of concept at industrial scale

Redox potential (Eh) control plays a significant role during sulfide mineral flotation by influencing the reactions on the surface of the minerals and accordingly the flotation behaviour. In this study, the metallurgical performance of typical copper sulfide minerals, molybdenite as well as gangue minerals (e.g., pyrite, tennantite, and enargite) under different pH and Eh conditions of the flotation cell were investigated. The copper and molybdenum processing plant at the Sungun complex-Iran were selected as a case study. For this purpose, Eh of flotation cells of phases 1 and 2 of copper and molybdenum processing circuits – Sungun complex – were measured by off-line method. After performing chemical analysis, the mineralogical study of the input load and products of each of the aforementioned flotation circuits in the rougher, cleaner, re-cleaner, and scavenger stages was performed. Based on the results, the potential in cells of phases 1 and 2 of copper concentration plants is in the range of −60 to −100 mV; and for the molybdenum plant, is in the range of −500 to −700 mV. The potentials of more than −100 mV in the phases of copper concentration plants have created suitable conditions for the separation of copper sulfide and molybdenite minerals from gangue minerals, especially pyrite. Adjustment of Eh in the range of −500 to −700 mV in the molybdenum processing plant has also led to the depression of copper minerals and the flotation of molybdenite, resulting in the effective separation of these minerals. However, grade analysis and mineralogical studies indicate the misplaced copper minerals into tailings, the passage of chalcopyrite and pyrite to molybdenum concentrate, the misplaced molybdenite to copper concentrate, and also the presence of minerals containing harmful elements such as arsenic in copper concentrate. Eh fluctuations in phase 1 and 2 of copper plants, the interaction of copper sulfide minerals, especially chalcopyrite with pyrite (and the depression of pyrite in Eh more than −100 mV), are reasons for the misplaced copper minerals into tailings. The interaction of chalcopyrite and pyrite with molybdenite and the high flotation tendency of molybdenite at the potential of +600 mV is the main factor in increasing the Cu and Fe grade in molybdenite concentrate. The interaction of copper minerals with arsenic-bearing minerals and the similar flotation behavior of these minerals in the potential of the rougher cells of the molybdenum processing plant has increased the arsenic grade in the copper concentrate or molybdenum tailings.

Effect of Cu(II) ions on millerite (β-NiS) flotation and surface properties in alkaline solutions

The presence of copper(II) ions in the process water used in the mineral processing industry has an impact on iron and nickel sulphide mineral flotation in both acidic and alkaline environments. Millerite (β-NiS) – a nickel sulphide mineral, has been found misreported to Cu concentrate, which negatively impact the performance of Cu/Ni separation. In this paper, we present a fundamental study on the effect of Cu(II) ions on millerite flotation and surface properties in alkaline solutions. Micro-flotation tests indicated that millerite flotation can be activated by conditioning with copper ions prior to KEX addition at both pH 9 and 12. The surface chemistry of millerite in the presence of Cu(II) was studied by mineral dissolution and EDTA extraction tests as well as XPS analysis to probe the underlying activation mechanism. At alkaline pH, the main copper species on millerite surface was Cu(I) sulphide with minor Cu(II) sulphide and Cu(II) oxide/hydroxide. The Cu(I) sulphide arose from the adsorption and reduction of Cu(II) species. Meanwhile, sulphur oxidation was affected upon the reduction of Cu(II) to Cu(I). Monosulphide species (S2-) at the surface was oxidized into disulphide species (S22-), resulting in less sulphoxy species (SxOy2-). There was no remarkable increase in nickel dissolution and growth in nickel hydroxide passivation layer upon the adsorption of Cu. In essence, copper ion activated millerite flotation under alkaline pH through affecting millerite surface oxidation.

Quantum-chemical substantiation of collecting properties of acetylene reagents in flotation of sulphide minerals

The paper presents the analysis results of known data and performed adsorption and spectral IR studies of MIG-4E, DMIPEK and DC-80 acetylene reagents in interaction with galena (PbS) and molybdenite (Mo2S) sulphide minerals. The IR spectra analysis of pure reagents and products of their interaction with the surface of sulphide minerals has showed that the adsorption of MIG-4E molecules takes place on the surface of lead sulphides, and DMIPEC molecules are adsorbed on the surface of molybdenite. Quantum-chemical calculations of the total potential energy of the complexes have shown that the complex formed by a molecule of MIG-4E – PbS of (HUMO) complexes by nucleophilic mechanism has 2514.0873 kcal/mol, which is almost an order of magnitude greater than the total potential energy (270.0439 kcal/mol) of MIG-4E – PbS (HUMO) complex formed by electrophilic mechanism. Analysis of the calculated data of the total potential energy of complexes formed by MIG-4E reagent molecules with PbS surface and DMIPEC molecules with Mo2S surface has showed that the total energy of π-complexes formed by reagents by electrophilic mechanism differs by 47.7% among reagent molecules and amounts to 270.0439 kcal/mol for (MIG-4E + PbS) complex, and 141.9386 kcal/mol for (DMIPEC + Mo2S) complex in the (HUMO) state. Such a difference in the values of total energies of the complexes can correlate with the conformational ability of DMIPEC reagent molecules. Usage of acetylene alcohols as additional selective collectors during flotation of a number of non-ferrous and precious metal ores has shown a significant increase in the extraction of target metals, which makes it possible to consider the reagents based on acetylene derivatives as promising for industrial applications.

Synergistic effects of frothers, collector and salt on bubble stability

This work investigates synergistic and antagonistic effects of flotation reagents and salt on the air–liquid interface and stability of air bubbles under quasi-static conditions. Frothers of different families (aliphatic alcohol, polypropylene glycol and propylene glycol methyl ether), potassium amyl xanthate (PAX), a common collector used in the flotation of sulphide minerals, and sodium chloride (NaCl) were employed in the study. Adsorption of frother and collector molecules from individual and mixed solutions was studied through surface tension and Quartz Crystal Microbalance with Dissipation (QCM–D) measurements, while bubble stability was examined by the coalescence time of the bubble pairs in these solutions. The results show that NaCl enhanced the adsorption of frothers, while PAX's impact on the adsorption of the frother was found to be rather insignificant compared to the salt. The bubble coalescence time measurements, however, pointed to a significant synergistic effect between PAX and two frothers i.e., Methyl Iso Butyl Carbinol (MIBC) and Di Propylene Glycol (DPG) as reflected in the improvement of bubble stability. In the ternary solution systems (frother/NaCl/PAX), the concentration of salt in the MIBC mixture solution was found to have an opposite impact on the bubble lifetime in the DPG and DPM solutions. For instance, bubble lifetime increased with higher NaCl concentrations added to the DPG and DPM solutions, whereas it decreased in the MIBC solutions.

Flotation separation mechanism for secondary copper sulfide minerals and pyrite using novel collector ethyl isobutyl xanthogenic acetate

Ethyl isobutyl xanthogenic acetate (EIBXAC) was used as a novel collector in the flotation of secondary copper sulfide minerals owing to its ability to separate copper and sulfur. The collectivity and selectivity mechanisms of this novel collector were investigated using single-mineral and artificial mixed-mineral tests, combined with adsorption tests, fourier transform infrared spectroscopy (FTIR) tests, and density functional theory (DFT) calculations. The results of the flotation indicated that EIBXAC had a better collecting effect than ammonium dibutyl dithiophosphate (ADD) on covellite and digenite, which had an insignificant effect on pyrite. The artificial mixed-mineral experiment indicated that EIBXAC could improve the grade of the copper concentrate while maintaining the same recovery, it had higher efficiency and selectivity. Based on the results of the adsorption and FTIR tests, the adsorption capacities of EIBXAC on the surfaces of covellite, digenite, and pyrite were quite different: Cu-S bonds were formed on covellite and digenite, and Fe-O bonds were formed on pyrite, which was also verified that EIBXAC was chemically adsorbed on the mineral surface. DFT calculations indicated that the adsorption capacity of EIBXAC for covellite and digenite was stronger than that of ADD, which had a weaker adsorption capacity for pyrite. This study can provide theoretical guidance for the application of EIBXAC.

Flotation separation of molybdenite from talc using a new inhibitor Artemisia sphaerocephala Krasch gum

In the flotation of sulfide minerals, the separation of molybdenite and talc is a difficult problem. Talc is the main gangue mineral of molybdenite, it has good natural hydrophobicity and a similar layered structure as molybdenite, so inhibitors are often used to separate them. But the reverse flotation method is often used to inhibit molybdenite, and the separation effect is not satisfactory. Therefore, an effective inhibitor is greatly needed. Here we showed a new inhibitor ASKG to separate molybdenite from talc. In microflotation tests, it was found that ASKG has a good depression effect on both molybdenite and talc. By adding collector SBX, the floatability of molybdenite can be enhanced without affecting the depression of ASKG on talc, and the effective separation of the two can be realized. The FTIR analyses and adsorption measurements revealed that the adsorption of ASKG on the talc surface occurred through hydrogen bond and hydrophobic interaction in physical adsorption. In addition, the competitive adsorption of ASKG and SBX on the surface of molybdenite was explored, and it was found that the first reagent reacted with molybdenite will hinder the adsorption of the later reagent on molybdenite and affect the floatability of molybdenite. The results showed that ASKG plays an excellent role in the separation of molybdenite and talc by positive flotation, which is of great significance for the separation of other minerals in mineral processing.

Synthesis and Characterization of Lead Dibutyl Dithiophosphate Nanoparticles

We examined the interaction of aqueous solutions of lead nitrate and sodium dibutyl dithiophosphate and showed the formation nanoparticles of lead dibutyl dithiophosphate. The effect of reaction parameters on the synthesis of nanoparticles was studied and the optimal conditions for the formation of their stable hydrosols were determined. The obtained products were investigated by methods of optical spectroscopy, dynamic light scattering. The average size of 15–20 nm, but due to the low surface charge, they are combined into larger aggregates. The UV‑vis spectra has absorption maximum at about 320 nm. TEM micrographs and Pb 2p, S2p XAS spectra revealed a composition and structure of the particles. These nanoparticles can play an important role in the flotation of sulfide minerals of nonferrous metals

Efficient flotation recovery of lead and zinc from refractory lead-zinc ores under low alkaline conditions

In this study, a new flotation approach, a low-alkaline and non-desliming process, was introduced for improving lead and zinc recoveries, lowering production cost and reducing environmental pollution. Lab-scale experiments results show that the new process contributed to the flotation of the complex mixed sulfide-oxide lead and zinc ore regarding two aspects: (1) High alkaline process (pH = 12±) was replaced by low alkaline process (pH = 9±) by using collector WS (a mixture of ethyl thiocarbamate, ammonium dibutyldithiophosphate and dithiophosphate-25) and combined depressant Na2S/ZnSO4/Na2SO3 for lead sulfide flotation; (2) Non-desliming process was successfully achieved by using collector MA (a mixture of ether amine, hydroxyethyl cellulose and polyacrylic acid) and combined depressant SHP/SS (sodium hexametaphosphate/sodium silicate) for zinc oxide flotation. And 43.37% Pb in the Pb concentrate was recovered, the corresponding Pb grade was 52.73%, total 84.42% Zn was recovered by the flotation of zinc sulfide minerals and zinc oxide minerals. Moreover, the two aspects of the new approach were systematically verified from lab-scale to industrial-scale application. The industrial-scale flotation tests show that Pb recovery in Pb concentrate increased by 1.86% compared with that of original system during industrial-scale tests period, and the Pb recovery increased by 4.09% compared with that of original system before industrial-scale tests period, while the Zn operating recovery in zinc oxide concentrate improved by 19.52%. Moreover, the total reagent cost of the whole new process significantly declined by 3.93 yuan per ton of ore.

Selective separation of chalcopyrite and talc using pullulan as a new depressant

As a gangue mineral, talc is usually associated with chalcopyrite. Therefore, the depression of talc is required in the field of sulphide mineral flotation. Herein, the depression mechanism of pullulan in the flotation separation of chalcopyrite from talc was investigated via flotation tests and characterisation techniques, such as Fourier transform infrared analysis (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The flotation test results showed that chalcopyrite can be selectively separated from talc with 20 mg/L pullulan as a depressant, and that the separation effect remains unaffected when the depressant dosage is increased to 80 mg/L. Additionally, the zeta potential, FTIR and adsorption measurements indicated that pullulan is selectively adsorbed on talc surfaces, and that talc surfaces adsorb more depressants than chalcopyrite. The XPS results indicated that the pullulan adsorption on talc surfaces is physical. The AFM results indicated that pullulan adsorption on talc surfaces forms polymer layers. Therefore, pullulan is considered a potential depressant of talc in the flotation industry.

Evaluation of the Use of Recycled Vegetable Oil as a Collector Reagent in the Flotation of Copper Sulfide Minerals Using Seawater

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.

Reaction behaviors of Pb and Zn sulfates during reduction roasting of Zn leaching residue and flotation of artificial sulfide minerals

To evaluate the feasibility of recovering Pb and Zn sulfides and Ag-containing minerals from Zn leaching residue by the process of reduction roasting followed by flotation, the reaction behaviors of Pb and Zn sulfates during this process were investigated. Chemical analysis showed that the transformation ratios of PbSO4 and ZnSO4 could reach 65.51% and 52.12%, respectively, after reduction roasting, and the introduction of a sulfidation agent could improve the transformation ratios of these sulfates. scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) revealed that temperature obviously affects the particle size, crystal growth, and morphology of the artificial Pb and Zn sulfide minerals. Particle size analysis demonstrated that the particle size of the materials increases after roasting. Flotation tests revealed that a flotation concentrate composed of 12.01wt% Pb, 27.78wt% Zn, and 6.975 × 10−2wt% Ag with recoveries of 60.54%, 29.24%, and 57.64%, respectively, could be obtained after roasting.

The Effect of Complexing Reagents on Flotation of Sulfide Minerals and Cassiterite from Tin-Sulfide Tailings

ABSTRACT Using a combination of UV-spectrophotometry, IR-Furie spectroscopy, analytical scanning electron (LEO 1420VP INCA OXFORD ENERGY 350) and laser (KEYENCE VK-9700) microscopy the effect of complexing reagents DBDTC, TMPPh, TOFA, and IM-50 on adsorption layer on the surface of chalcopyrite, galena, arsenopyrite, and cassiterite was studied. The individual formation character of the adsorption layer on each of the listed minerals was identified and the sizes of thin discrete films of the newly formed reagent phase, the strength of their fixation, and the coverage area of the mineral surface were determined. Kinetic photometry established the effective flocculation of cassiterite slimes by a thermomorphic polymer with a phosphine group TMPPh, which helps to reduce the loss of tin with fine fractions. TOFA is a selective tin collector and has advantages over IM-50 in terms of the fixation contrast on cassiterite and quartz. Tests of the developed reagent modes using a composition of complexing reagents have shown the possibility of obtaining sulfide and tin concentrates that met the requirements of metallurgical processing.

The role of non-frothing reagents on bubble size and bubble stability

Xanthates are widely used for the flotation of most sulphide minerals. As well as xanthates, various reagents (e.g. sodium hydrosulphide, NaHS) are used in sulphide mineral flotation to improve selectivity. Both xanthates and NaHS target the solid–liquid interface and modify the surface to achieve sufficient difference in wettability between the gangue and target mineral. This study examines the role of potassium amyl xanthate (PAX) and NaHS at the air–liquid interface in the presence of a frother, methyl isobutyl carbinol (MIBC). The separate and joint effects of these reagents on the stability of bubbles were studied by measuring bubble size in a batch flotation cell and the lifetime of bubble pairs using a bubble coalescence apparatus. The results of the bubble coalescence experiment with the PAX/MIBC mixture showed that the presence of PAX in a concentration as low as 1 ppm significantly increased the bubble lifetime compared to the MIBC only solution. The lifetime of the bubbles was longer in the NaHS/MIBC mixture, although this might be due to the gain in the liquid viscosity in the presence of high NaHS concentrations. Depending on the concentration of PAX in the solution, the bubbles showed unstable, metastable and ultra-stable behaviors. The influence of PAX and NaHS on the Sauter mean diameter of bubbles was studied and both had a notable effect on inhibiting bubble coalescence, reducing the bubble size by 26%, while in the PAX/MIBC mixture, the size of the bubbles was largely dominated by the concentration of MIBC. Overall, the results strongly suggested that the role of PAX and the synergistic effect of PAX, NaHS and MIBC in modifying the air–liquid interface should be considered when using these reagent combinations.