Sphalerite Recovery Research Articles

The Effect of Novel Submicronic Solid Activators on Sphalerite Flotability

In this study, we examine the effect of novel submicronic activators made from copper minerals and copper-rich concentrate on sphalerite flotability. The copper minerals and copper concentrate are ground in a vibratory micromill and ultrasonically treated to obtain submicronic sphalerite activators. Histograms show that the concentration of copper particles in the activator after treatment is 92%–94%, with particle sizes of 105–115 nm. The results concerning monomineral flotation showed that sphalerite flotation is possible with the use of submicronic copper particles as an activator. At the same time, the consumption of mineral copper is much lower (by 10 times) than that of copper sulfate. The best results are achieved when submicronic particles of covellite and bornite (with a 60% concentration of particles 300–500 nm in size) were used. Sphalerite recovery amounted to 80%, which is higher than the recovery obtained with the use of copper sulfate by 2% but is 2% lower compared to the use of copper oxyhydroxide. The flotation effect of the submicronic activators on sphalerite was tested in laboratory conditions using polymetallic ore from one of Kazakhstan’s deposits. It is shown that the novel submicron activators based on bornite and copper concentrate exhibit much lower consumption rates and can replace the more expensive copper sulfate at the same Zn content (54.8%–54.9%), obtaining recovery rates of 95.69%–96.57%.

The mechanism of surface activation in sphalerite by metal ions with d10 electronic configurations: Experimental and DFT study

The activation mechanism of metal ions with d10 inert electronic configurations on sphalerite (ZnS) were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS), combined with density functional theory (DFT). Flotation experiments showed that the addition of activators increased sphalerite recovery by 50–70 %. The XPS results indicated that these inert cations with d10 electronic configurations formed stable metal sulfides (Cu2S, CuS, Ag2S, CdS, and HgS) on the sphalerite surface. The FTIR results demonstrated that the activated sphalerite enhanced the adsorption stability of butyl xanthate on the sphalerite surface. DFT studies found that metal ion introduction reduced surface relaxation and decreased the band gap on the sphalerite surface, both of which increased butyl xanthate adsorption. Finally, it was suggested in this study that the energy required for the d10 to d9s1 electron transition and the polarization could be used to predict the potential sphalerite activator.

Selective depressing mechanism of H-acid monosodium salt on flotation separation of graphite and sphalerite

Micro-flotation experiments, Fourier transform infrared spectroscopy (FT-IR) tests, Zeta potential tests, X-ray photoelectron spectroscopy (XPS) analysis and molecular dynamics simulation were used to study the flotation behavior, separation and depressing mechanisms of graphite and sphalerite in the presence of H-acid monosodium salt (HAMS). Under the optimum flotation conditions, the recovery of sphalerite and graphite in the concentrate of mixed mineral flotation was 93.37% and 4.98%, respectively. Zeta potential tests and XPS analysis indicated that HAMS was considerably adsorbed on graphite surfaces but virtually absent on sphalerite surfaces. The FT-IR tests revealed that HAMS had no significant chemisorption on graphite surfaces. Molecular dynamics simulation inferred that the hydrophobic interaction between the naphthalene ring in HAMS and graphite was responsible for the adsorption of HAMS on the graphite surface.

Optimization of shape factor by the response surface method, and the effect on sphalerite flotation recovery

Various morphological parameters that affect the flotation recovery of sphalerite were modelled and optimized using the response surface method (RSM). The effects of roughness value, shape factor, and collector concentration were investigated using the central composite full design method. The results were evaluated by analysis of variance. The optimum roughening time was found to be 25 minutes, the optimum roughness value was 2.9071 um, and the optimum collector concentration was 0.001 M. Using these values, a flotation recovery of 98.01% was obtained. Similarly, in shape factor studies, the optimum grinding time was 15 seconds, the optimum roundness value 0.7421, and the optimum collector concentration 0.0009 M, which resulted in a flotation recovery of 94.30%. The average error between the optimization results and the experimental results was estimated to be less than 6%, and the R2 values were greater than 90%. The study shows that RSM can be effectively applied in finding the economic optimum condition for obtaining maximum flotation recovery with minimum reagent consumption.

Flotation Recovery of Sphalerite in Sea Water: A Feasibility Study

Mining and mineral processing industry adversely affects ecosystems and communities in nearby areas, including high freshwater consumption and scarcity. That is why the emerging global trend is to use sea water in flotation to recover valuable minerals from finely disseminated base metals ores. Recent studies investigate sea water flotation of copper, molybdenum, nickel sulphides and pyrite, while flotation of sphalerite, the main valuable mineral for zinc production, remains uncovered. This paper examines the feasibility of sphalerite flotation by conventional collectors in artificial sea water using a bubble-particles technique and frothless flotation tests. Potassium isopropyl xanthate (PIPX) and sodium isopropyl dithiophosphate (SIDTP) were used as collectors, and copper sulphate was introduced as the activator, while zinc sulphate and sodium sulphide were used as depressants. We examined the most common size fractions of sphalerite: medium (−74 + 44 μm) and fines (−44 μm). The findings showed the feasibility of sphalerite flotation in artificial sea water. We also established correlations between the rate of bubble-particle attachment and the sphalerite flotation recovery resulting in the growth of flotation recovery with the increase of the bubble-particle attachment rate. The results can be used as guidelines in choosing flotation reagents for sphalerite flotation in sea water. Another practical application of the results is the potential for sustainable development of the industrial sector, ecosystems and societies due to the replacement of fresh water by sea water, although further technological and environmental studies are required.

Thermodynamics and Electrochemistry of the Interaction of Sphalerite with Iron (II)-Bearing Compounds in Relation to Flotation

The flotation recovery of sphalerite depends on the inorganic reagents concentrations in the liquid phase of suspension and pH. This paper presents the results of studies of the interactions of iron (II) containing ions with the sphalerite surface in water solutions at different pH levels. The thermodynamic and electrochemical studies were carried out to analyze possible interactions of sphalerite with iron (II) sulfate in a water environment and relate them to sphalerite flotation with potassium butyl xanthate and sodium dibutyl dithiophosphate. The results of the thermodynamic calculations revealed the possibility of interaction of the sphalerite surface with iron (II) hydrolysis products. The effect of the hydroxide ions concentration on precipitation of iron (II) hydroxides was examined. The findings showed that at pH = 8 there were no precipitates observed in water solutions of FeSO4. Increasing pH of the solutions from 8 to 12 resulted in the formation of iron (II) hydroxides. The potentiometric studies revealed that in slightly alkaline solutions the Fe2+ and FeOH+ cations are potential-determining. In conclusion, the flotation tests with thiol collectors show the activation effect of iron (II) sulphate on sphalerite at low dosage and pH 12. This is evident by a higher flotation recovery of sphalerite at these conditions.

Mechanism of germanium doping in sphalerite on copper ion activation: A DFT study

In this study, density functional theory was used to calculate the activation of Cu ions on germanium-bearing sphalerite (110) surfaces and the difference in the activation of Cu ions in sphalerite with different Ge concentrations. The results show that, with an increase in Ge content, the projected density of states on the germanium-bearing sphalerite (110) surface moves toward lower energy, and the energy gap between the Cu 3d and S 3p orbitals on the surface of the germanium-bearing sphalerite becomes larger, and the covalency and bonding strength of the CuS bond weaken. Through calculation and analysis of three different Cu activation models, namely Cu substitution, Cu(II) adsorption, and Cu(OH)2 adsorption, it is concluded that an increase in Ge content can hinder the Cu activation of sphalerite and can adversely affect the recovery of sphalerite and the enrichment of valuable elements in the flotation process.

Ore mineral characteristics as rate-limiting factors in sphalerite flotation: Comparison of the mineral chemistry (iron and manganese content), grain size, and liberation

A sphalerite deportment study using QEMSCAN® was conducted to understand the distribution of the sphalerite grains with varying iron and manganese content during a multi-stage Zn-Pb-Cu flotation of a complex ore. In addition, the study aims to understand the effect of sphalerite chemistry in relation to grain size and liberation. Mineral chemistry, grain size, and degree of liberation were extracted for 497,704 sphalerite grains, composed of approximately 31 million energy-dispersive spectrometer (EDS) analysis points. Bulk chemical assay and electron probe microanalysis (EPMA) were used to validate the extracted sphalerite chemistry data from QEMSCAN®. Sphalerite recovery in the final zinc concentrate improved with increasing iron and manganese content for sphalerite grains containing up to 9% Fe and 2% Mn. At higher iron and manganese content, sphalerite recovery decreased or plateaued. Conversely, an opposite trend was observed for losses to the copper-lead concentrate. The obtained results indicated that considering the ore mineral characteristics, physical factors such as grain size and liberation have a more significant effect on sphalerite flotation than the presence of iron and manganese.

Effect of Magnesium on the Hydrophobicity of Sphalerite

The use of untreated recycled water has negative effects in the flotation of zinc sulfide ores due to the presence of dissolved species, such as magnesium and calcium. Although it has been found that magnesium is a more potent depressant than calcium, it has not been investigated in this role or for the effect of adding sodium carbonate. The results of an investigation to evaluate the effect of magnesium on the hydrophobicity of Cu-activated sphalerite conditioned with Sodium Isopropyl Xanthate (SIPX) are presented. Zeta potential of natural and Cu-activated sphalerite as a function of the conditioning pH and Cu(II) concentration, respectively, was first evaluated. Later, the effect of pH and presence of magnesium on the contact angle of Cu-activated sphalerite conditioned with SIPX was studied; it was also evaluated the effect of sodium carbonate to counteract the effect of magnesium. Cu-activation enhances the zeta potential of sphalerite up to a concentration of 5 mg/L. Contact angle tests, thermodynamic simulation, and surface analysis showed that magnesium hydroxide precipitates on the sphalerite surface at pH 9.6, decreasing its hydrophobicity. Addition of sodium carbonate as alkalinizing agent precipitates the magnesium in the form of a species that remained dispersed in the bulk solution, favoring the contact angle of Cu-activated sphalerite and, consequently, its hydrophobicity. It is concluded that the use of sodium carbonate as alkalinizing agent favors the precipitation of magnesium as hydromagnesite (Mg5(OH)2(CO3)4∙4H2O) instead of hydroxide allowing the recovery of sphalerite.

The flotation separation of sphalerite from pyrite through a novel flotation reagent system of FeCl3-CuSO4-aminotriazolethione

To reduce the consumption of lime in mineral processing means reducing CO2 emission. Herein, a novel FeCl3-CuSO4-APTT (4-amino-5-pentyl-1,2,4-triazole-3-thione) approach was first developed to replace the common CaO-CuSO4-xanthate technology during flotation separation of sphalerite from pyrite. APTT exhibited a stronger collecting power towards pyrite than sphalerite, while the attendance of ferric chloride significantly depressed the floatability of pyrite and sphalerite, and its inhibition against pyrite was stronger than that to sphalerite. The addition of cupric sulfate not only removed the inhibition of ferric chloride against sphalerite, but also promoted its floatability. Nevertheless, the floatability of the FeCl3-depressed pyrite was hardly recovered by cupric sulfate. Using FeCl3 as the depressor against pyrite and CuSO4 as the activator for sphalerite, APTT realized a selective and efficient flotation recovery of sphalerite from pyrite in the weakly-acidic medium. FTIR (Fourier Transform Infrared Spectroscopy) and contact angle indicated that the pretreatment with FeCl3 and CuSO4 in sequence significantly weakened APTT adsorption on pyrite, while benefited sphalerite adsorption towards APTT, resulting in creating a dramatical difference of surface hydrophobicity and flotation recovery between the two minerals. XPS (X-ray photoelectron spectroscopy) elucidated that after modifying sphalerite surface successively through FeCl3, CuSO4 and APTT, the Cu-APTT complexes were detected on sphalerite, which were of significance to hydrophobizing its flotation.

Interaction mechanism of the adopted reagents in the flotation recovery of sphalerite and pyrite from a galena flotation tailing: First-principles calculations

Sphalerite (ZnS), galena (PbS) and pyrite (FeS2) are the important metallic sulphide minerals. These three sulphide minerals are often associated with each other, and large amounts of sphalerite and pyrite are lost in the galena flotation tailings. In this study, the flotation method was employed to recover sphalerite and pyrite from a galena flotation tailing waste. The reagent scheme, including Cu2+ activator and butyl xanthate (BX) collector, can efficiently recover sphalerite and pyrite to obtain a two-mineral mixed concentrate with the Zn and Fe grades of ∼17 % and ∼26 %, respectively, in the sphalerite-pyrite bulk rough flotation. Quicklime (CaO) depressant in combination with BX collector can efficiently separate sphalerite and pyrite to obtain the two products in the sphalerite/pyrite separation rough flotation: the sphalerite concentrate with the Zn grade of ∼33 % and the pyrite concentrate with the Fe grade of ∼36 %. The first-principles calculations were employed to study the interaction mechanism of the adopted reagents in the recoveries of sphalerite and pyrite from the galena flotation tailing. This study provides an important reference for the recoveries of sphalerite and pyrite from similar galena tailings.

Influence of Terpenic Oil on Flotation Behavior of Sphalerite and Implication for the Selective Separation

Terpenic oil (TO) is commonly used as a flotation frother for the selective separation of sulfide minerals. As a frother, most reports have mainly focused on its effect on froth stability and froth entrainment, whereas its influence on the floatability of sulfide minerals has received little attention. In this work, the influence of TO on the flotation behavior of sphalerite was investigated by using microflotation tests, contact angle and zeta potential measurements, and FT-IR and SEM-EDS analyses. Microflotation tests conducted in a modified Hallimond tube indicated that compared with the collector potassium butyl xanthate (KBX), the flotation recovery of sphalerite was significantly increased when TO was added to the pulp, but the recovery of Cu-activated sphalerite with the addition of TO was lower than that with the addition of KBX. Contact angle measurements demonstrated that the contact angle of sphalerite was distinctly increased by the addition of TO, but the contact angle of sphalerite treated with TO was lower than that treated with KBX after Cu activation. Zeta potential measurements demonstrated that the zeta potential of sphalerite particles was slightly decreased when treated with TO, and the isoelectric point (IEP) was decreased from 3.3 to 3.1 due to the interaction of TO with sphalerite particles. FT-IR and SEM-EDS confirmed that TO could be adsorbed on the sphalerite surface on the formation of the oil film due to its low solubility, thereby increasing the surface hydrophobicity of the sphalerite. In addition, the TO absorbed on the surface acts as a bridging role and promotes the hydrophobic agglomeration of sphalerite particles. These results suggest that except for froth entrainment, the influence of TO on the flotation behavior of sphalerite may be another reason for the misreporting of sphalerite in concentrates.

Electrocoagulation: A Promising Method to Treat and Reuse Mineral Processing Wastewater with High COD

Mineral processing wastewater contains large amounts of reagents which can lead to severe environmental problems, such as high chemical oxygen demand (COD). Inspired by the wastewater treatment in such industries as those of textiles, food, and petrochemistry, in the present work, electrocoagulation (EC) is applied for the first time to explore its feasibility in the treatment of wastewater with an initial COD of 424.29 mg/L from a Pb/Zn sulfide mineral flotation plant and its effect on water reuse. Typical parameters, such as anode materials, current density, initial pH, and additives, were characterized to evaluate the performance of the EC method. The results showed that, under optimal conditions, i.e., iron anode, pH 7.1, electrolysis time 70 min, 19.23 mA/cm2 current density, and 4.1 g/L activated carbon, the initial COD can be reduced to 72.9 mg/L, corresponding to a removal rate of 82.8%. In addition, compared with the untreated wastewater, EC-treated wastewater was found to benefit the recovery of galena and sphalerite, with galena recovery increasing from 25.01% to 36.06% and sphalerite recovery increasing from 59.99% to 65.33%. This study confirmed that EC is a promising method for the treatment and reuse of high-COD-containing wastewater in the mining industry, and it possesses great potential for wide industrial applications.

Effect of a Small Amount of Iron Impurity in Sphalerite on Xanthate Adsorption and Flotation Behavior

Through industrial testing at the Huize lead-zinc mine, it was found that the floatability of sphalerite varied greatly with the iron impurity content. Three kinds of Huize sphalerites with iron contents of 2.30 wt.%, 3.20 wt.% and 4.66 wt.%, were used to study the influence of small amounts of iron impurity in the sphalerite on xanthate adsorption and flotation behavior. The flotation experiments showed that the flotation recovery increased with the increase in iron impurity content. Fourier Transform infrared spectroscopy (FTIR) and Ultraviolet–visible (UV-VIS) spectra showed that the adsorbed products of xanthate on the surface of three kinds of sphalerite were metal xanthate. The adsorption capacity measurements showed that the saturation absorption of xanthate on sphalerite increased with the increase in iron impurity content. The cyclic voltammetry curve and Tafel curve showed that with the increase in iron impurity content, sphalerite was more easily oxidized and the adsorption rate of xanthate on the surface of sphalerite increased obviously. To summarize, a small amount of iron impurity was beneficial to the recovery of sphalerite.

Recovery of sphalerite from a high zinc grade tailing

In this work, the flotation recovery of sphalerite and pyrite from an old high zinc grade tailing was studied. In particular, the effect of different flotation reagents such as collector, auxiliary collector, depressant, activators, and frother on the flotation performance were investigated. The synergic effect of the collector blends, as well as frother blends were also studied. In addition, the effect of the pre-conditioning of flotation pulp with scrubbing or ultrasonic on the selective separation of sphalerite and pyrite minerals were studied. More than 73% of the sphalerite was recovered from the accumulated tailings in the rougher stage. The pulp viscosity was considerably increased by increasing the pH from 5.5 to 10.5. As a result, sphalerite recovery and Zn selective separation were both considerably dropped. It was also found that frothers (MIBC and A65) have a synergic effect, and their mixture showed better metallurgical results than when each frother were solely used. The pre-conditioning with scrubbing or ultrasonic resulted in a major increase in the sphalerite floatability.

Contribution to Improve Water Process Recycling in the Flotation Plant of a Complex Zn-Pb-Cu Sulphide Ore

Moroccan Mining Company of Guemassa (MCG) produces from a complex sulphide ore three concentrates using Aerophine 3418A in the flotation circuits of galena and chalcopyrite and potassium amyl xanthate for sphalerite recovery. Water scarcity in the flotation plant area imposes to think of reducing fresh water use by recycling the tailing water process. Substitution of PAX by Aerophine 3418A in the zinc circuit will result in a tailing water process containing one kind of collector which could be easily controlled and recycled in the overall MCG plant. Optimizing and modeling study using experimental design methodology showed that the targeted substitution of PAX in MCG plant is possible: at flotation time of 5 min; 40 g/t of collector; 200 g/t of CuSO4 and pH of 12, Aerophine 3418A is more selective toward Fe than PAX. Zinc recovery reached 72% when flotation time was extended to 15 minutes.

Effect of copper ions on surface properties of ZnSO4-depressed sphalerite and its response to flotation

The activation mechanism of copper sulfate (CuSO4) for sphalerite surfaces depressed with zinc sulfate (ZnSO4) and their interactions were investigated through microflotation experiments, zeta-potential determination, X-ray photoelectron spectroscopy (XPS), xanthate adsorption experiments, time-of-flight secondary-ion mass spectrometry (TOF-SIMS) and local electrochemical impedance spectroscopy (LEIS). The microflotation experimental results indicated that addition of ZnSO4 decreased sphalerite recovery and that CuSO4 can activate sphalerite depressed with ZnSO4 during flotation. The highest negativity of the zeta potential was achieved after adding xanthate + ZnSO4 + CuSO4, indicating that the addition of copper ions can improve adsorption of the collector on depressed sphalerite surfaces. XPS was used to identify the mechanisms of the interactions of ZnSO4 and CuSO4 with the sphalerite surface. Xanthate adsorption experiments showed that the xanthate adsorption capacity increased greatly after treatment of depressed sphalerite with copper ions. TOF-SIMS indicated that copper ions were adsorbed on the surface of the depressed sphalerite. LEIS analysis showed that, copper ion can replaces zinc ion on mineral surface. These results show a sphalerite surface depressed with ZnSO4 can be activated by copper ions, thereby increasing its hydrophobicity and floatability.

Density functional theory study of cyanide adsorption on the sphalerite (1 1 0) surface

Cyanidation tailings in gold plants often contain lots of sphalerites that are difficult to recycle by flotation because of the strongly depressive effect of the residual cyanide. To reveal the depression mechanism of cyanide on sphalerite, the adsorption of isolated cyanide molecule (CN) at different coverages on the sphalerite (1 1 0) surface were studied by means of density functional theory. The calculated results show that the adsorption energy of per CN molecule drops as the increase of adsorbed CN molecule coverage, indicating that the adsorption structure becomes more thermodynamically stable. Cyanide molecule adsorption on sphalrite (1 1 0) surface prior occurs on the atop site of surface Zn atom, in which the Zn 3d orbital donates electrons to the 2p orbital of C forming a d-p back donating bond, leading to the production of hydrophilic zinc cyanide complexes that serve as strong obstacles to the flotation recovery of sphalerite in cyanidation tailings. Electron transfer from mineral surface to the adsorbed CN molecules takes place during the process of CN adsorption, and the surface atoms lose more electrons when the coverage of adsorbed CN molecules is high, weakening the reactive activity of Zn and S atoms on the sphalerite (1 1 0) surface.

Reprocessing of a Southern Chilean Zn Tailing by Flotation—A Case Study

The reprocessing of tailings can have economic and environmental benefits compared to the processing of primary ore deposits. In this paper we present the characterization of a tailings dam in southern Chile by means of mineralogical and geochemical investigations, focusing on sphalerite and trace elements with the aim to investigate a potential reprocessing. The assessment is followed by a flotation study, focusing on the recovery of sphalerite with a high selectivity towards sulfidic and non-sulfidic gangue minerals. An in-depth analysis of a selected test based on mineral liberation analysis data is used to refine the liberation, concentration and flotation weighting function for future investigations.

A ToF‐SIMS investigation on correlation between grinding environments and sphalerite surface chemistry: implications for mineral selectivity in flotation

AbstractChanges in mineral surface properties during grinding play a key role in flotation performance. Time of flight secondary mass spectrometry (ToF‐SIMS) surface chemical analytical studies have shown that flotation separation of sphalerite from chalcopyrite is significantly affected by the oxidation of metal species on the surface of sphalerite. The intensity of iron oxyhydroxyl species on the surface of sphalerite has a positive correlation with poor recovery of sphalerite. Given the link between the presence of oxide species on the surface of sphalerite and a lower recovery during copper flotation, a laboratory study was initiated to evaluate the potential for sphalerite surface oxidation control and improving recovery through grinding. For the investigation, a ball mill that allowed for monitoring pulp chemistry during grinding was utilized to study the impact of grinding conditions on selective flotation of sphalerite. ToF‐SIMS was used to identify and measure the variability in sphalerite surface species as a result of the different test parameters. Variable mill parameters include two types of grinding media, aeration conditions, addition of FeSO4, and altering the pyrite content in the feed ore. ToF‐SIMS analyses of mill discharge samples identified higher intensities of iron oxyhydroxyl species on sphalerite surface subsequent to grinding with mild steel balls, in condition of aeration, use of FeSO4, and by increasing the pyrite content of the feed ore. The higher adsorption of iron oxyhydroxyl species on the surface of sphalerite should be consistent with the lower recovery. To verify this, bench‐scale flotation tests in the presence and absence of FeSO4 were performed; results correlated iron oxyhydroxyl species with the poor sphalerite recovery. Copyright © 2017 John Wiley & Sons, Ltd.