Sulfide Ore Flotation Research Articles

Unveiling the depression role of quercetin in selective flotation separation of chalcopyrite from pyrite at low alkalinity

In flotation, the separation and concentration of copper-iron sulfide ores are usually carried out at high alkalinity to depress pyrite, and plenty of lime could block the flotation pipeline and affect the recovery of precious metals during practical operation. Herein, the current research hotspot to achieve the separation of copper-iron sulfide ores under low alkalinity. This paper presented an eco-friendly reagent, quercetin, for the flotation separation of chalcopyrite and pyrite, and investigated the effect on the flotation performance of the two minerals. The interaction mechanism of quercetin with mineral was demonstrated using zeta potential measurements, atomic force microscopy (AFM), surface adsorption measurements, Fourier-transform infrared spectroscopy (FT-IR), and X-ray Photoelectron Spectroscopy (XPS). The flotation results showed that the depressive effect of quercetin on pyrite was more pronounced in comparison to its impact on chalcopyrite at pH 8.0, and the chalcopyrite recovery reached 90 %, whereas that of pyrite was under 10 %. The surface analysis revealed quercetin chemisorption on the mineral surface through interaction with metal sites. In the presence of quercetin, the quercetin significantly diminished the ability of pyrite to adsorb xanthan but had minor effects on the adsorption of chalcopyrite.

A comparison of dry and wet grinding on gold-bearing sulphide ore flotation

This study investigates the hypothesis that dry grinding prior to flotation can mitigate the adverse effects of galvanic interactions, improve the selectivity of gold flotation compared to wet grinding, and offer additional benefits due to water scarcity concerns and high water treatment costs. The effects of dry and wet grinding on the flotation behavior of gold-bearing sulphide ore were studied comparatively in terms of flotation test results and pulp chemistry parameters (pH, Eh, and dissolved oxygen). In addition, flotation tests without conditioning were also conducted following dry grinding in an attempt to minimize water contact further. Results demonstrated that dry grinding increased pulp potentials and dissolved oxygen levels, implying more oxidative conditions. Despite a lower mass pull with dry grinding, flotation recoveries and grades of gold and chalcopyrite were comparable to wet grinding, while dry grinding enhanced pyrite flotation at the rougher stage. Notably, flotation without conditioning effectively rejected pyrite and achieved higher grades for gold and chalcopyrite, indicating selective flotation. Therefore, dry grinding before flotation emerges as a viable alternative for gold and chalcopyrite flotation due to its improved selectivity while carefully optimizing flotation strategies and reagents to maximize recoveries.

Flotation of Copper Sulfide Ore Using Ultra-Low Dosage of Combined Collectors

Copper sulfide ores frequently co-occur with pyrite, presenting a significant challenge for their selective separation during beneficiation processes. Despite advancements in flotation technology, there remains a critical need for efficient methods to enhance copper recovery while suppressing pyrite interference, particularly without compromising the associated precious metals such as gold and silver. Current practices often struggle with achieving high selectivity and recovery while maintaining environmental sustainability. Here, we investigate the efficacy of a ternary collector mixture consisting of ammonium dibutyl dithiophosphate (ADD), butyl xanthate (BX), and ethyl xanthate (EX) for the selective flotation of copper sulfide from a complex ore containing 0.79% Cu and associated precious metals (0.233 g/t Au and 5.83 g/t Ag). A combination of lime and hydrogen peroxide as inhibitors was employed to suppress pyrite effectively under alkaline conditions (pH = 11.33). The results demonstrate that the optimized ternary collector system (ADD:BX:EX at a ratio of 1:0.5:0.5) significantly improves the copper grade and recovery at an ultra-low dosage of 10 g/t. The optimized flotation method using the combined collectors and inhibitors effectively separated chalcopyrite from pyrite, achieving a copper concentrate with 20.08% Cu content and a recovery of 87.73%. Additionally, the process yielded notable recoveries of gold (9.22%) and silver (26.66%). These findings advance the field by providing a viable and environmentally conscious approach to the beneficiation of sulfide ores, potentially serving as a blueprint for processing similar mineral deposits while minimizing reagent usage and costs.

Effect of low dissolved oxygen on chalcopyrite-molybdenite separation flotation at high altitude areas

Given the scarcity of conventional low-altitude high-quality copper–molybdenum resources, people gradually explore mining opportunities in elevated regions. Molybdenite in high-altitude ores is initially recovered with chalcopyrite, which is then separated and floated to produce refined molybdenite. There are few studies on the influence of the sulfide ore flotation process under high-altitude and low dissolved low-dissolved oxygen (DO) environments. In the present study, a flotation plant is designed and assembled to simulate the flotation of chalcopyrite at high altitudes by controlling the partial pressures of N2/O2 and DO under different altitude conditions, using the DO value as a standard. UV/VIS, electrochemical, and contact angle measurements were used to reveal the effect of conditions at 4600 m DO = 4.0 mg/L at altitude on chalcopyrite–molybdenite separation. Pure mineral flotation results indicate that a low DO environment at high altitudes favors the separation process and reduces the number of inhibitors. The mechanism of chalcopyrite inhibition at high altitudes still relies on the adsorption of large amounts of Fe(Ⅲ)-O/OH and hydrophilic polysulfides on the surface. Results reveal the reason for the relatively low inhibitor dosage in the chalcopyrite–molybdenite separation flotation process under low DO conditions at high altitudes. The findings also confirm that enhanced collector removal at high altitude altitudes is conducive to implementing a pathway toward a more efficient separation flotation process.

Upgrading of talc-bearing copper-nickel sulfide ore by froth flotation using sodium phytate as depressant

Copper-nickel sulfide ores, as important sources of copper and nickel metals, always have large amount of clay-type gangue minerals like talc. In this work, selective flotation of copper-nickel sulfide ore was achieved by using a selective depressant of sodium phytate. Microscale flotation results show that sodium phytate can selectively and effectively depress talc flotation, but has a minor effect on the floatability of chalcopyrite and pentlandite. In batch-scale flotation tests of feed ore, containing 0.35% Cu, 0.68% Ni and 24.57% MgO, potassium butyl xanthate was employed as the collector in rougher (200 g/t), scavenger-1 (100 g/t), scavenger-2 (50 g/t) and scavenger-3 (25 g/t), and sodium phytate depressant was used in rougher (300 g/t) and cleaner-1 (100 g/t) stages of closed-circuit flotation to obtain a concentrate containing 2.66% Cu (79.7% recovery), 5.38% Ni (83.01% recovery), and only 6.39% MgO. The contact angle analysis showed that sodium phytate significantly improved the hydrophilicity of talc, but it only slightly increased the hydrophilicity of chalcopyrite and nickelpyrite. The FTIR and XPS tests showed that chemisorption of sodium phytate occurred on talc surface by the interaction between P-O/PO and Mg active sites. This work indicates that sodium phytate has strong potential as an inhibitor for the selective separation of talc from copper-nickel sulfide ores.

SODIUM DITHIONITE AS A PYRITE DEPRESSANT IN GOLD ORE FLOTATION

Sodium dithionite (Na2S2O4) is a widely used reducing agent to control pulp potential (Eh) and pyrite depressant in sulfide ore flotation. In this study, the pyrite depressant effect of sodium dithionite on gold ore flotation was investigated at pH 8 and pH 10.5 comparatively in terms of gold, chalcopyrite, and pyrite recoveries and grades. The presence of sodium dithionite resulted in a drop of approximately 50–70 mV in the Eh values, regardless of the studied pH values, confirming the reducing effect of sodium dithionite. The effects of sodium dithionite on gold and chalcopyrite grades and recoveries were quite limited, especially at pH 10.5. At pH 8, the utilization of sodium dithionite slightly decreased gold and chalcopyrite recovery and grades, while the decrease in pyrite recovery and grades was remarkable. Both pyrite recovery and grade were reduced from 79.5% to 54.7% and 15.3% to 10.7% by the utilization of sodium dithionite at pH 8. In conclusion, it is considered that the selective flotation of gold and chalcopyrite from pyrite can be achieved at a lower pH accompanied by a slightly reduced Eh by the utilization of sodium dithionite.

Anisotropic adsorption of xanthate species on molybdenite faces and edges and its implication on the flotation of molybdenite fines

Utilizing xanthate in bulk flotation of Cu-Mo sulfide ores is inevitable, but the implication of xanthate on the flotation of molybdenite fines is barely understood. In this study, the influence of sodium butyl xanthate (SIBX) on the flotation of molybdenite fines and the interaction mechanism was comprehensively investigated by micro-flotation tests, contact angle, adsorption capacity, electrochemical tests, atomic force microscopy (AFM), Fourier Transform Infrared Spectrometer (FTIR), X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. Micro-flotation tests indicated that SIBX significantly enhanced the flotation of molybdenite fines across a wide pH range. Contact angle, adsorption capacity, Tafel curves, AFM, FTIR and XPS results suggested both xanthate and dixanthogen species adsorbed on molybdenite surfaces, thus improving the hydrophobicity of both edges and faces. Rest potential measurements clarified dixanthogen species dominated on faces while xanthate ions prevailed on edges. DFT calculations elucidated dixanthogen physically adsorbed (−66.06 kJ/mol) on faces while xanthate chemisorbed (−235.62 kJ/mol) on edges via the hybridization of two S atoms within SIBX with two Mo atoms to form highly covalent bonds. This work first clearly unveiled the anisotropic adsorption mechanism of SIBX species on faces and edges, significantly improving the flotation efficiency of molybdenite fines.

Control of Non-Ferrous Metal-Sulfide Minerals’ Flotation via Pulp Potential

Studies on the dependence of the technological results of non-ferrous sulfide ore (copper—arsenic-bearing and non-arsenic-bearing—lead–zinc, and polymetallic) flotation on the pulp potential Eh are reviewed. Findings on the relation of Eh and collectorless flotation are presented. Changes in the pulp potential due to different gas applications and various reagent additions are considered. The influence of the grinding medium on the pulp Eh and hence on the flotation results is presented through various examples. The relation between the oxidation–reduction potential and reagent effects is exhibited and explained. pH–Eh ranges of different minerals’ flotation, as recorded in various studies, are summarized and visualized jointly for all mentioned ores. It is concluded that the pulp Eh value, considered together with the pH value, is a useful means for flotation selection controlling and deserves further research, especially under industrial conditions. Some problems and difficulties in using pulp Eh for flotation control are discussed.

Flotation behavior and surface analytical study of synthesized (octylthio)aniline and bis(octylthio)benzene as novel collectors on sulfide minerals

Six novel collectors, 2-(octylthio)aniline (2-OA), 3-(octylthio)aniline (3-OA), 4-(octylthio)aniline (4-OA), 1,2-bis(octylthio)benzene (2-OB), 1,3-bis(octylthio)benzene (3-OB) and 1,4-bis(octylthio)benzene (4-OB) were synthesized and newly introduced as collectors in the flotation of copper sulfide ores. Collector PAX was used as a standard to evaluate the flotation performance of the novel collectors using two kinds of ore samples. The results showed that the novel collectors, especially collector 2-OA, had the strongest flotation capacity, with the highest copper recovery of 95.6% from the chalcopyrite sample at pH 9 and a collector dosage of 100 g/t, while PAX yielded only 66.5% under the same flotation conditions. Likewise in the flotation of copper sulfide ore sample, the flotation performance of the novel collectors was generally improved than that of PAX. The flotation kinetics study showed that the 2-OA novel collector had a faster reaction rate than PAX. The adsorption experiments revealed excellent adsorption characteristics of the novel collectors on the chalcopyrite surface with an adsorption rate of up to 99.3%. UV analysis showed that the novel collectors were more reactive to copper than iron, confirming that the novel collectors enhance the copper recovery in sulfide ore flotation. The infrared spectral analysis exhibited that the novel collectors were adsorbed on the surface of chalcopyrite with the generation of a new substance.

Synergistic Effect of Frequently Found Ions in the Flotation of Pb-Zn Sulfide Ores on Air/Water Interface

The aqueous ions influence the properties of air bubbles and, therefore, the recovery of flotation. This study aims to reveal the synergistic effect of frequently found ions in the flotation of Pb-Zn sulfide ores. In this context, dynamic surface tension measurements, bubble coalescence time, Sauter mean diameter (SMD), bubble size distribution (BSD), and dynamic foam stability (DFS) measurements were carried out using artificial process waters (APWs). APW with the minimum ion concentration is expressed as “APW1” with the ionic strength (I) of 0.03 mol/dm3. The concentration of the ions in APW1 was increased by 3, 5, and 10 times, and thus APW3 (I = 0.08 mol/dm3), APW5 (I = 0.13 mol/dm3), and APW10 (I = 0.26 mol/dm3) were prepared, respectively. The results of this study indicated that the surface tension increased slightly in the presence of APW related to the ion concentration. Potassium ethyl xanthate (KEX) at high concentrations was effective in the reduction of surface tension. As the APW concentration increased, finer bubbles were obtained with a narrower size range. The stability of the foam increased with butyl glycol (BG) and APW concentration. There was no need to use a frother (BG) for the flotation experiments in the presence of APW1 or APWs with higher ionic strength.

Effect of regulating dissolved oxygen concentration in pulp with aerated gas on pyrite flotation

Moderate oxidation is beneficial to the flotation of sulfide ores, but the exact dissolved oxygen (DO) concentration suitable for flotation is still unclear. In this work, a self–made vacuum aeration flotation equipment was designed and assembled to accurately control the DO concentration in pulp by adjusting the relative proportion of O2/N2 during aeration, and the effect of DO concentration on the floatability and surface properties of pyrite as well as the interaction between pyrite and xanthate was studied. Microflotation experiments, contact angle, time–of–flight secondary ion mass spectrometry, X–ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, electrochemical and localized electrochemical impedance spectroscopy measurements were conducted in this investigation. The results showed that the flotation recovery of pyrite could be remarkably affected by DO concentration in pulp; it increased first and then decreased with the increase of DO concentration; an optimal DO concentration (DO = 3.3 mg/L) was helpful for pyrite flotation recovery; both the formation of dixanthogen and the avoidance of excessive iron oxide/hydroxide formed on pyrite surface were the key to improve the pyrite recovery. This research is expected to be applied in optimizing the flotation separation by DO-pH combined detection and regulation, strengthening the green flotation of sulfide ore with low collectors, and the design and manufacture of new closed and efficient sulfide ore flotation equipment.

Comprehensive Utilization of Pyrite Concentrate Pyrolysis Slag by Oxygen Pressure Leaching

The preparation of high-purity sulfur and pyrrhotite by pyrolysis holds great potential to realize the high-value utilization of pyrite concentrate (FeS2), i.e., a by-product during the flotation of sulfide ore. In this study, the pyrrhotite obtained from the pyrolysis of pyrite concentrate was taken as the study object, and the effects of acid types, initial acidity, leaching time, leaching temperature, oxygen pressure, and liquid-to-solid ratio on the leaching behavior of pyrrhotite under oxygen pressure, were explored. The results show that elemental sulfur and hematite-based iron residue can be obtained by oxygen pressure leaching of pyrrhotite. It is found that the optimal experimental conditions for pyrrhotite oxygen pressure leaching are hydrochloric acid with 0.8 mol/L of initial acidity, 5 h of leaching time, 0.8 MPa of oxygen partial pressure, and 9:1 of liquid to solid ratio at 150 °C; moreover, the yield of sulfur reached 88.37%. Under optimal conditions, the leaching ratios of Fe, Pb, and Zn were 19.8%, 92.25%, and 99.11%, respectively. The sieved leaching residue was roasted at a low temperature of 500 °C, where the grade of Fe in the obtained hematite iron powder was 61.46%, and the grades of Pb, Zn, and S were 0.082%, 0.024%, and 0.1%. Clearly, the results meet well with the standard of the first grade of pyrite cinder, and this process realizes the comprehensive recovery of Fe and S resources in pyrolysis slag, which provides a superb technical route for the high-value utilization of pyrite concentrate.

Application of inverse gas chromatography to bench scale flotation of sulphide ore

ABSTRACT Inverse gas chromatography (IGC) is receiving increasing attention due to its high precision and ease of application in determining various characteristics of a wide variety of materials of different shapes and morphologies. This study details an experimental investigation into the application of the IGC technique to the flotation of sulphide minerals. Rather than giving the surface energy, the trends associated with the various concentrates and tailings are described. Bench-scale flotation experiments of a nickel-copper sulphide ore were conducted in a Denver flotation cell. The IGC analyses were carried out on the timed concentrates, as well as on the final tailings, in order to evaluate the correlation between surface energetics and the flotation response of the ore particles. The results indicated that the floatability of the concentrates was directly related to the surface energy of the particles. Both dispersive and specific components of surface free energy increased by increasing the necessary time for the particles to be floated, which was consistent with the obtained values for the work of adhesion to water. However, the flotation response of the tailings was not consistent with the expectations from the surface energy value. The significance of the sample composition, particle size distribution, and their consequences in surface energy-flotation response relationship were also observed.

Interfacial Adsorption Mechanism of Diethyldithiocarbamate in High-Sulfur Residue Flotation

Diethyldithiocarbamate (DDTC) is employed in the sulfide ore flotation process due to its excellent collection performance. Herein, we investigated the interfacial adsorption behavior of DDTC on the four main mineral phases of high-sulfur residue: sulfur, pyrite, sphalerite, and lead sulfate. The adsorption behavior of DDTC and H2O, namely, the adsorption structure and the energy and electron localization function cross section, were explored using density function theory calculation. The results were helpful in constructing a coadsorption model of DDTC and H2O, which was validated by pure mineral flotation and characterization of Fourier transform infrared spectra. The coadsorption model indicated that the adsorption of DDTC on sulfur, sphalerite, and lead sulfate was weak with physical bonding, while its adsorption on pyrite was strong with chemical bonding. Practical bench-scale high-sulfur residue flotation was performed, and the result was different from that obtained from pure mineral flotation. Our developed model predictions and mineral fugacity pattern analysis were synergistically used to explain this difference. Overall, this work proposes for the first time a coadsorption model of DDTC and H2O and provides important insights into interfacial adsorption in high-sulfur residue flotation.

Mineralogical characteristics of sulfuric acid formation during bacterial oxidation of flotation concentrate

The article presents the results of a study on the formation of sulfuric acid in the process of bacterial oxidation of sulfide ore flotation concentrate. The results are estimated from the point of view of the thermodynamics of the course of some bacterial oxidation reactions, calculating the standard enthalpies of formation - (ΔН0298), entropy (ΔS0298) and Gibbs energy of formation (ΔG0298) of some reactions and substances at 298 K. Conclusions about the formation of sulfuric acid based on X-ray phase and electron scanning microscope results of changes in mineralogical and elemental composition in the processes of bacterial oxidation of flotation concentrate are substantiated.

Comprehensive Utilization of Tailings in Quartz Vein-Hosted Gold Deposits

The aim of this study was to develop a comprehensive technology for the utilization of tailings from quartz vein-hosted gold deposits. We investigated the recovery potential and separation process for gold, feldspar, and quartz from tailings samples collected from the Jinqu gold mine in Henan province, China. The sequence of the principal flowsheet of the comprehensive utilization of gold, feldspar, and quartz from the tailings samples was determined according to the process mineralogy and corresponding experiments. The residual gold in the tailings was extracted, and both feldspar and quartz concentrates were recovered according to the flowsheet of selective desliming, flotation of gold-bearing sulfide ore, removal of iron-containing impurities, flotation separation of feldspar, and purification of quartz. The quartz concentrate met China’s industrial standard for raw-material quartz sand for producing high-grade glass, such as cover glass for touch electronics and TFT LCD liquid crystal substrate glass. The feldspar concentrate also met China’s ceramic industry standards. The established process provides an efficient way for recovering the main valuable minerals in tailings from quartz vein-hosted gold deposits. Moreover, this study demonstrates the synthetic recovery of the same type of gold tailings.

Improved visible-light-driven activity of micro graphite/BiOI nanocomposite for effective removal of xanthate from wastewater

The visible light responsive micro-powder graphite (Mic-g)/BiOI nanocomposite was prepared by hydrothermal method to effectively remove the xanthate residue in sulfide ore flotation wastewater. The effects of different weight ratios of graphite in composites on photocatalytic activity were investigated. Under visible light, the 5wt% Mic-g/BiOI composite exhibited the highest degradation efficiency (94.36%) and the largest rate constant (0.02273 min−1) which was about 4.3 times higher than that of pure BiOI. The enhanced photocatalytic activity was mainly due to the synergy of a good contact interface between BiOI and graphite with good conduction resulting in the carriers’ rapid transfer. In addition, the mechanism of enhanced photocatalytic activity during the reaction was also investigated. The free radical trapping experiment demonstrated that the main active species in the photocatalytic process are •OH. This work provides a simple and effective approach to synthesizing the visible-light-driven photocatalyst with high efficiency for xanthate wastewater treatment.

Effect and mechanism of the xanthate/H2O2 addition order on flotation separation of chalcopyrite and sphalerite

Oxidation will affect the flotation of sulfide ore, but both sulfide ore and xanthate are easily oxidized, the role of oxidation in the flotation separation of sulfide ore is still unclear. In this study, different single mineral flotation tests were designed to explore the role of hydrogen peroxide (H2O2) in the flotation separation of chalcopyrite and sphalerite, and artificial mixed minerals tests was conducted to verify the selective depression effect of H2O2. Ultraviolet–visible (UV–vis) spectrometer, inductively coupled plasma-mass spectrometry (ICP-MS) measurement, microcalorimetry measurement, contact angle measurement, and Fourier transform infrared (FTIR) spectrometer were used to discuss the depressive mechanism of H2O2 on sphalerite. Flotation tests with different dosing methods show that mineral self-oxidation is the main reason for its depression. Both the chalcopyrite and sphalerite can be oxidized by H2O2, and the PBX adsorbed on its surfaces can also be desorbed by H2O2. However, sphalerite is easier to oxidize than chalcopyrite, and the PBX adsorbed on the surface of sphalerite is also easier to be desorbed. Therefore, sphalerite is selectively depressed by H2O2 in the flotation of chalcopyrite in the order of “mineral + PBX + H2O2″.

Effect of the foaming performance of ammonium dibutyl dithiophosphate on the flotation of slime-containing copper sulfide ore

Effect of the foaming performance of ammonium dibutyl dithiophosphate on the flotation of slime-containing copper sulfide ore

The effects of ultrasonic wave on heterogeneous coagulation and flotation separation of pentlandite-serpentine

It is well known that in the flotation of copper-nickel sulfide ore, pentlandite and serpentine are easy to form hetero-aggregation, which makes it difficult to separate them. Therefore, dispersion operation is indispensable, including chemical and physical dispersion. Chemical dispersion is usually achieved by adding dispersing reagents, which is widely used in mineral flotation, while the study of ultrasonic dispersion in copper-nickel sulfide ores in physical dispersion is less reported. Thus ultrasonic dispersion technology was introduced to weaken the hetero-aggregation and to improve the floatability of pentlandite. Through the implementation of a series of conditional tests of influence factors including ultrasonic site, ultrasonic probe type, ultrasonic time, and ultrasonic power, the optimum ultrasonic dispersion system was demined, and the results showed that the ultrasonic power was the key factor affecting the dispersion of pentlandite-serpentine. Then the dispersion mechanism of ultrasonic was revealed by means of supernatant turbidity measurements, particle-size distribution (PSD) analyses, scanning electron microscopy (SEM), and atomic force microscope (AFM) in succession. Coupled with supernatant turbidity measurements, PSD analyses and SEM images of flotation concentrates all confirmed that the ultra-fine serpentine particles coating on the coarse pentlandite particles were effectively dispersed. AFM analyses depicted the morphological changes of surface roughness treated by different ultrasonic power, and confirmed that the ultrasonic power of 200 W could increase the surface roughness and floatability of pentlandite but decrease that of serpentine. Thus, the difference in floatability between the two minerals were enlarged so as to achieve efficient separation of the two minerals. The results of this research are helpful to understand clearly the mechanism of ultrasonic dispersion of pentlandite-serpentine, which provides an alternative dispersion technology and exhibits great potential for further study and application.