Galena Surface Research Articles

Influence of surface oxidation rate on the flotation of sphalerite and galena inhibited by gum arabic

Differences in the flotation behavior of galena and sphalerite using potassium permanganate (KMnO4) and gum arabic (GA) alone and using a mixture of KMnO4 and GA were investigated. The single mineral flotation tests revealed that when KMnO4 and GA were used individually, galena and sphalerite flotation were inhibited, but the reagent dosages required were large. Sphalerite was strongly inhibited by the addition of a tiny amount of GA after oxidation with KMnO4 while galena was not inhibited under the same conditions. Following oxidation by KMnO4, galena and sphalerite exhibited a significant 83 % difference in flotation recovery when 10 mg/L GA was used, which clearly showed the potential for the combined use of KMnO4 and GA to achieve flotation separation of galena from mixed lead-zinc ores. The inhibitory effect of GA on sphalerite was investigated through a combination of analytical techniques, including Microcalorimetry, Fourier Transform Infrared (FTIR) Spectroscopy, contact angle measurements, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray (EDS) analysis. The results displayed that sphalerite had a much higher oxidation rate than galena, resulting in more oxides and hydroxides. As a result, the sphalerite surface exhibits an increased availability of active sites favorable to GA adsorption, thereby impeding Butyl xanthate (PBX) adsorption. However, the galena surface was able to absorb PBX, resulting in mineral separation.

Release Behavior of Pb(II) Ions on the Galena Surface: Dissolution Experiment, DFT Calculation, and MD Simulation

In this study, the release behavior of Pb(II) ions from the galena surface and their occurrence forms in the migration process under acid and alkaline conditions were investigated by dissolution experiment, the density functional theory (DFT) calculation, and molecular dynamics (MD) simulation. The dissolution experiments indicated that acidic and high alkaline conditions are more beneficial for the release of Pb(II) rather than neutral and weak alkaline conditions. The quantum chemical calculations indicated that under acidic conditions, H+ can destroy the surface structure of galena, leading to the dissolution of Pb2+ from the mineral surface into the liquid phase. OH− can also damage the galena surface to a certain extent under alkaline conditions. Additionally, MD simulations were further utilized to study the occurrence forms of Pb(II) ions in alkaline solutions. The results suggested that with a certain concentration of OH−, Pb2+ ions will form lead hydroxide aggregates, while excessive OH− could lead to the dispersion and dissolution of the lead hydroxo complexes. The surface morphological observation by SEM can well support the calculation and simulation results.

Exploring the Mechanism of 4-Hydroxy-1,3,5-triazine-6-thiol Collector on Depressant-Free Flotation Separation of Galena from Sphalerite.

The flotation separation of galena from sphalerite was commonly implemented under pH > 10.5, which led to the consumption of lime. In this paper, 2-diethylamine-4-hydroxy-1,3,5-triazine-6-thiol (DEHTT) was synthesized and introduced as a highly selective collector to perform the depressant-free flotation separation of Pb/Zn sulfide minerals. The microflotation results indicated that 8.0 × 10-7 mol/L DEHTT recovered 94.17% galena and 26.67% sphalerite from their mixture at pH 8.5 regulated by Na2CO3, and under the same conditions, sodium isobutyl xanthate (SIBX) floated out 94.94% galena and 50.41% sphalerite, deducing a superior flotation selectivity of DEHTT in comparison to SIBX. In situ AFM images displayed the more preferable adsorption of DEHTT on galena in comparison to that on sphalerite. The results of adsorption thermodynamics and kinetics inferred that the adsorption of DEHTT onto the galena surface was a spontaneous endothermic chemical process. XPS further indicated that DEHTT combined with interface Pb atoms to form the -S-Pb and -O-Pb bonds. The special affinity of DEHTT to galena achieved the selective flotation separation of galena from sphalerite without the addition of lime and depressants.

Enhancing flotation efficiency: Optimizing galena and chalcopyrite separation through high-temperature pre-oxidation with recycled sulfuric acid

Galena and chalcopyrite pose challenges in their separation owing to their similar surface chemistry. The flotation separation of galena and chalcopyrite significantly depends on the use of depressants. However, conventional depressants are often associated with several drawbacks, such as toxicity and inefficiency. Hence, exploring efficient and environmentally friendly techniques to separate galena and chalcopyrite is vital. This study investigated the use of sulfuric acid as a surface oxidant for the pre-oxidation treatment of galena and chalcopyrite at high temperatures. This approach facilitated acid recycling and eliminated the need for multiple flotation chemicals. The floatability of galena and chalcopyrite was investigated through micro-flotation. The results revealed that at a pre-oxidation temperature of 100℃, galena exhibited a recovery rate of only 9.98 %, while chalcopyrite maintained a recovery rate of 96 % across the temperature range. The selective depressant mechanism of sulfuric acid in the flotation separation of galena and chalcopyrite was investigated through scanning electron microscopy, zeta potential measurements, X-ray photoelectron spectroscopy, thermodynamic calculations, and electrochemical analyses. The results indicated that the high temperature facilitated the dissolution of the sulfide layer on the galena surface. Consequently, S2− ions underwent oxidization into SO42− to form a stable oxide film on the galena surface through interaction with Pb2+. Conversely, the high-temperature pre-oxidation had a minimal effect on the surface of chalcopyrite, indicating selective oxidation benefits. Findings from the pre-oxidation floatation separation test of galena–chalcopyrite mixtures revealed the efficient and thorough separation of the two minerals under high-temperature pre-oxidation conditions. The lead concentrate obtained from the floatation process exhibited a Pb grade of 79.38 % and a recovery rate of 97.17 %, while the Cu concentrate featured a Cu grade of 32.14 % and a recovery rate of 97.06 %. Additionally, the sulfuric acid solution was recycled. Overall, this study provides a sustainable and cost-effective approach for the green separation of copper–lead sulfide ores.

Study on flotation behavior and mechanism of galena flotation separation from chalcopyrite by sodium periodate depressant

The successful separating galena and chalcopyrite by flotation presents difficulties owing to their analogous surface chemical properties. This study investigated sodium periodate (SP) as a novel depressant for selectively oxidizing and modifying chalcopyrite and galena surfaces, enabling successful flotation separation. In micro-flotation tests were carried out at pH 8.5 and SP concentration of 5 × 10−4 mol/L. The grades of Cu and Pb in the copper concentrate were 27.87 % and 23.13 % with recoveries of 81.22 % and 27.78 %, respectively. SP selectively inhibited galena floatability while preserving chalcopyrite floatability. The selective depression mechanism research of SP in flotation separation process showed that galena surface hydrophobicity was significantly reduced by SP, which in turn prevented the collecting agent from adhering to galena. In the presence of SP, hydrophilic species such as PbSO4 and Pb(OH)2 were generated on the surface of galena, which decreased its ability to float. Conversely, on the chalcopyrite surface, hydrophobic products such as CuS2, CuSn, and S0 were formed, having little effect on its floatability. A model was developed to elucidate the mechanism underlying the selective flotation separation of the chalcopyrite and galena using SP.

Separation of galena and pyrite via green organic macromolecules at low alkalinity: Flotation response and surface adsorption mechanisms

Pyrite must be separated from galena during the beneficiation stage because it releases toxic gases during pyrometallurgy. However, the separation of the two minerals presents a huge obstacle as they have comparable hydrophobicity. This work offers an environmentally friendly pyrite depressant, pullulan polysaccharide (PP), for concentrating galena. Single mineral flotation showed that the ability of PP to deteriorate floatability was significantly stronger for pyrite than for galena within the pH range of 6.00 − 12.00. PP preadsorption assisted in separating galena from pyrite in a low-alkalinity pulp. The recovery of galena was 71.20 % higher than that of pyrite in the binary mineral flotation system. Characterization results confirmed that the Fe sites of pyrite were more susceptible to forming a stable coordination with the O atoms of PP’s C−O−H group compared to the Pb sites of galena. PP can impede the sodium butyl xanthate (BX) sorption on the pyrite surface, thus effectively depressing the pyrite. By contrast, the sorption of BX onto the galena surface was unaffected by PP, and the galena remained floatable. Thus, PP could be considered as an alternative to conventional inorganic depressants in the galena–pyrite flotation system. This work provides a scientific reference for the green and sustainable exploitation of non-ferrous metal resources.

Separation of copper-lead using 2,5-dimercapto-1,3,4-thiadiazole as chalcopyrite depressant: Adsorption and hydrophilicity studies

Galena separation from chalcopyrite poses a notable challenge in mineral processing, owing to the involvement of high dosages of traditional process reagents and substantial environmental impact. This study addresses this challenge by introducing 2,5-dimethoxy-1,3,4-thiadiazole (DMTD) as a chalcopyrite depressant using sodium ethyl xanthate (NaEX) as a collector. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses showed that DMTD can be adsorbed on the surfaces of chalcopyrite and galena, but the adsorption on chalcopyrite is stronger than that on galena. UV–vis, zeta potential and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses revealed that DMTD impeded the adsorption of NaEX on chalcopyrite; moreover, NaEX could desorb the DMTD adsorbed on galena and re-adsorb it on galena. Surface hydrophilicity tests revealed that DMTD significantly enhanced the hydrophilicity of chalcopyrite in the presence of NaEX, and galena was selectively separated from chalcopyrite using 1×10− 4 mol/L DMTD at pH exceeding 5. The recovery of galena remained >90 %, while that of chalcopyrite drastically decreased to <5 %. Furthermore, artificial-mixing experiments confirmed the separation effect of DMTD as a chalcopyrite depressant. Notably, this study avoids environmental pollution caused by traditional depressants, offering a potential green approach to achieve effective flotation separation of copper–lead sulfide ore.

The flotation separation of galena from pyrite with 2-dialkylamino-s-triazine-4-thiol-6(1H)-thione sodium at pH ∼8.0: Emphasize on adsorption mechanism

To achieve an eco-friendly flotation separation of galena from pyrite under the low alkaline and depressant-free conditions, the triazine-dithione surfactants, such as 2-dimethylamino-s-triazine-4-thiol-6(1H)-thione sodium (DMN), 2-diethylamino-s-triazine-4-thiol-6(1H)-thione sodium (DEN) and 2-dibutylamino-s-triazine-4-thiol-6(1H)-thione sodium (DBN) were designed as the special collectors for galena. The micro-flotation results showed that the collecting capacity of these three collectors towards galena was in the order of DBN > DEN ≫ DMN, being consistent with their hydrophobization ability. In-situ AFM observed the aggregation of DBN on the whole surface of galena, which significantly enhanced the contact angle of galena. UV spectra and zeta potential recommended that the affinity of DBN towards lead ions and galena was much stronger than ferrous/ferric ions and pyrite. DFT (density functional theory) calculation revealed DBN’s two exo-S atoms were of its electron-donating center. And XPS confirmed the bonding interaction of the two exo-S atoms with Pb(Ⅱ) atoms on/in galena surface. DBN owned the mild electron-donating capacity and strong electron-accepting ability, and realized the eco-friendly flotation separation of galena from pyrite at pH ∼8.0.

Density Functional Theory Study on Structure and Properties of Sulfurized Cerussite (110) Surface

Cerussite is an essential lead oxide mineral with increasing economic importance as lead sulfide resources deplete. This study utilizes density functional theory (DFT) to investigate the structural and electronic properties of the sulfurized cerussite (110) surface. The results show that when the cerussite crystal cleaves along the (110) plane, only the surface layer atoms undergo relaxation to reconstruct the surface, while the atoms located deeper have almost no impact on the reconstructed surface structure. The Pb atoms on the cerussite (110) surface react with the sulfurizing agent to form a PbS deposition layer with a structure similar to galena. This PbS deposition layer is tightly adsorbed onto the lead oxide layer through Pb-S bonds formed by S and subsurface lead oxide structure Pb atoms. The chemical reactivity of Pb atoms in the PbS layer on the sulfurized cerussite (110) surface is more potent than that of Pb atoms on the galena surface; additionally, the Pb atoms closer to the lead oxide layer exhibit slightly higher chemical reactivity than those farther away. This study provides insight into sulfurized cerussite surfaces’ structure and properties at an atomic level and assists in explaining the floating behavior of cerussite.

Electrochemistry and DFT study of galvanic interaction on the surface of monoclinic pyrrhotite (0 0 1) and galena (1 0 0)

The electrochemical interaction between galena and monoclinic pyrrhotite was investigated to examine its impact on the physical and chemical properties of the mineral micro-surface. This investigation employed techniques such as electrochemistry, metal ion stripping, X-ray photoelectron spectroscopy, and quantum chemistry. The electrochemical test results demonstrate that the galena surface in the electro-couple system exhibits a lower electrostatic potential and higher electrochemical activity compared to the monoclinic pyrrhotite surface, rendering it more susceptible to oxidation dissolution. Monoclinic pyrrhotite significantly amplifies the corrosion rate of the galena surface. Mulliken charge population calculations indicate that electrons are consistently transferred from galena to monoclinic pyrrhotite, with the number of electron transfers on the mineral surface increasing as the interaction distance decreases. The analysis of state density revealed a shift in the surface state density of galena towards lower energy levels, resulting in decreased reactivity and increased difficulty for the reagent to adsorb onto the mineral surface. Conversely, monoclinic pyrrhotite exhibited an opposite trend. The XPS test results indicate that galvanic interaction leads to the formation of hydrophilic substances, PbSxOy and Pb(OH)2, on the surface of galena. Additionally, the surface of monoclinic pyrrhotite not only adsorbs Pb2+ but also undergoes S0 formation, thereby augmenting its hydrophobic nature.

Improving separation of sphalerite and galena by surface oxidation behavior regulation using calcium lentisulfonate as depressant

BackgroundSphalerite and galena often exist in mixed form and are difficult to separate effectively. The effect of surface oxidation behavior regulation on the depression of calcium lentisulfonate (CLS) was studied in galena and sphalerite. MethodsFlotation experiment, contact angle experiment, X-ray photoelectron spectroscopy (XPS) analysis and microcalorimetric experiment were used to study the effect and mechanism of modulation of surface oxidation behaviour on CLS on the depression of galena flotation. Significant findingsThe results show that CLS can depress both galena and sphalerite. The oxidizing agent H2O2 oxidizes galena significantly faster than sphalerite. The treatment with H2O2 induces the formation of more oxidation products, such as PbSO4, on the surface of galena, enhances the adsorption of CLS and makes the surface of galena hydrophilic, thus reducing the recovery of galena in the flotation process. On the other hand, the treatment of the activator ethylenediaminetetraacetic acid (EDTA) reduces the amount of oxidation products ZnSO4 on the sphalerite surface, and CLS loses the active site that can be adsorbed on the galena surface, making the galena surface hydrophilic. In view of the huge hydrophobicity difference between sphalerite and galena, flotation separation is achieved.

Galvanic interaction between galena and pyrite with dithiothreitol and its effects on flotation performance

With the advancement of green mine construction and the increasing difficulty of lead–sulphur resources, the traditional lime high-alkalinity lead–sulphur separation technology has exposed many shortcomings. In this study, based on the galvanic interaction of galena and pyrite, an environmental-friendly depressant dithiothreitol (DTT) was used to separate pyrite and galena under low alkalinity. In addition, the mechanism of DTT was revealed by electrochemical, ion dissolution, contact angle, zeta potential and DFT calculation. The results indicated that the galvanic interaction between galena and pyrite promoted the oxidation of galena and the dissolution of Pb2+ from the surface of galena, and Pb2+ would be adsorbed on the pyrite surface and increase the floatability of pyrite. DTT could selectively depress pyrite at low alkalinity. The interaction mechanism of DTT was that DTT could weaken the galvanic interaction of galena and pyrite and complex lead ions. In addition, DTT was adsorbed on the pyrite surface through the Fe-S bond, and the pre-adsorbed DTT hindered the adsorption of DDTC on the pyrite surface, thus the pyrite flotation was depressed.

Mechanism of Cu-Pb selective flotation separation based on quercetin as a novel depressant

This study presents an organic reagent, quercetin, as a flotation depressant used to effectively separate chalcopyrite and galena. Quercetin and O-isopropyl-N-ethyl thionocarbamate (IPETC) are used as depressants and collectors, respectively, and results of micro-flotation tests showed that quercetin can depress galena and has less effect on chalcopyrite. Tests of artificially mixed samples of the chalcopyrite and galena show that the separation effect of quercetin as a depressant is better than that of sodium sulfate and sodium silicate combined depressant, it is close to that of potassium bichromate as a depressant, that is, it has the potential to be a depressant to achieve selective separation of chalcopyrite and galena. The X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy results demonstrate that quercetin can chemisorb with oxidized metal sites on minerals’ surfaces. Results of the contact angle, adsorption capacity, and Atomic Force Microscope show that quercetin has comparable adsorption amounts on both minerals’ surfaces, and can hinder the IPETC adsorption on the mineral surface, but the amount of IPETC adsorb on chalcopyrite is much higher than on galena surfaces. The differences in the adsorption of the collector on their surface are the main reason for realizing the separation of chalcopyrite from galena.

Utilizing phosphonyl carboxylic acid copolymer as an efficient depressant for flotation separation of chalcopyrite from galena: Experimental and DFT study

The research proposes an innovative galena depressant, known as Phosphonyl carboxylic acid copolymer (POCA), to enhance the efficiency of flotation separation between chalcopyrite and galena. Mineral flotation tests were conducted to investigate the flotation performance of chalcopyrite and galena. The inhibition mechanism of POCA on galena was studied using multiple characterization techniques including Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) testing, Zeta potential testing, X-ray photoelectron spectroscopy (XPS) analysis, atomic force microscopy (AFM) testing, contact angle testing, time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis, and density functional theory (DFT) calculations. In the flotation test, at a concentration of 10 mg/L sodium butyl xanthate (SBX) and pH 9, adding 50 mg/L POCA can reduce the flotation recovery of galena from 83.50 % to below 5 %, whereas the recovery of chalcopyrite was almost influenced. The testing conducted via ICP-OES revealed that POCA promotes the dissolution of Pb2+ from the galena surface. The adsorption of POCA on the galena surface was confirmed through zeta potential testing, XPS testing, contact angle, AFM testing, and ToF-SIMS analysis, it was noted that POCA exhibited high levels of adsorption on the galena surface. Density Functional Theory (DFT) calculations suggest that the chemical interaction between the sulfonic acid present in POCA and the Pb2+ active site of galena is regarded as the primary inhibition mechanism.

Weak alkaline flotation separation of galena from sphalerite with 6-butylamino-1,3,5-triazine-2(1H)-thione-4-thiol sodium

The reduction of lime usage in flotation separation of lead–zinc sulfide ores has an interesting topic for protecting environment and recovering valuable metal minerals. In this study, BN (6-butylamino-1,3,5-triazine-2(1H)-thione-4-thiol sodium) was introduced for the first time as a selective collector for galena flotation. The results of UV spectra, adsorption capacity, zeta potential and in-situ AFM manifested that BN exhibited the selective affinity towards Pb2+ over Zn2+ ions, and preferred to adsorb on galena surface, not on sphalerite. The FTIR and XPS further uncovered that BN assembled on galena via bonding its sulfur atoms with lead ions of galena to form the surface BN-Pb complexes. The micro-flotation findings revealed that BN returned the stronger collecting power and higher selectivity than isobutyl xanthate during flotation separation of galena from sphalerite, and achieved their effective separation at low alkaline conditions (pH ∼ 8.0). This study also offers an enlightenment for the design of chelating collectors suitable for use under weak alkaline conditions.

Green separation of galena from molybdenite by flotation using DL-dithiothreitol as a depressant

Developing an environment-friendly depressant to separate galena from molybdenite by flotation remains greatly challenging. Herein, the nontoxic DL-dithiothreitol (DLD) was used as a galena depressant in a molybdenite–galena flotation system. Flotation experiments showed that a recovery difference of 88.45 % was achieved in a binary mixed-mineral system with a DLD dosage of 40.00 mg/L at pH 8.00, indicating that DLD significantly reduced the floatability of galena while barely altering that of molybdenite. The adsorption mechanism of DLD on the surfaces of galena and molybdenite were investigated by various characterization techniques. Results showed that DLD can coordinate with unsaturated lead ions on the galena surface through its sulfhydryl groups. DLD stably adsorbed onto the galena surface because of the presence of chemical bonding (Pb–S), which significantly changed the surface potential of galena. Molybdenite cannot chemisorb DLD because only saturated sulfur atoms were exposed on its cleavage surface. Hence, the selective adsorption of DLD enhanced the hydrophilicity of the galena surface without affecting the hydrophobicity of the molybdenite surface. Evidently, DLD was a high-performance and promising industrial application of galena depressant. This study provided new insights into the separation of molybdenite and galena, thereby facilitates the sustainable development of the mining industry.

The effects of NaCl addition on the particle-bubble interactions of galena in the presence of xanthate

This work investigated the effects of NaCl addition on galena flotation in the presence of xanthate. The micro-flotation experiments were performed using NaCl solutions which also included xanthate, at pH 9 (±0.1). Our results indicated that galena recovery improved for higher NaCl as well as higher xanthate concentrations.A pH-dependent chemisorption model for the galena surface, with the addition of xanthate adsorption was calibrated using measured zeta potential values. We propose that xanthate adsorption on galena can take place via two separate mechanisms. The first mechanism involves direct xanthate chemisorption to specific surface sites. The second mechanism involves lead/xanthate complexes formed in the bulk solution. These lead/xanthate complexes attach on the galena surface as hydrophobic lead xanthate salts.The galena-air bubble interactions are repulsive in 1 mM NaCl, with or without xanthate, consistent with the lower galena recovery measured experimentally. An increase to 100 mM NaCl, irrespective of the xanthate addition, resulted in attractive galena-air bubble total interaction energies. The agreement with the experimental results shows the effectiveness of the charge regulated model for estimating the galena and air bubble behaviours during flotation in NaCl solutions.

Experimental and computational study on the adsorption mechanism of silver ions on galena surface

With the increased use of silver in industry, a lot of wastewater containing silver is produced. If this wastewater is not treated, it will seriously impact both the ecological environment and human life. In order to effectively remove Ag+ from silver-containing wastewater, this study innovatively developed a natural mineral-based adsorption material (galena). The effects of reaction time, galena dosage, starting concentration, initial particle size, temperature, and solution pH on Ag+ removal were first studied using batch studies. The outcomes demonstrated that the initial Ag+ concentration of 50 mg/L reduced to 0.086 mg/L with the reaction duration of 15 min, the galena dose of 5 g/L, the initial particle size of −400 mesh (38 μm), the reaction temperature of 25 °C, and the pH of 5. The adsorption results show that the removal behavior of Ag+ by galena is consistent with the pseudo-second-order adsorption kinetic model and the Freundlich isothermal adsorption model, with the maximum adsorption amount of 18.78 mg/g. Solution chemical analysis shows that in the Ag+-NO32−-Pb2+-S2− system, Ag+ mainly reacts with S2− and forms a precipitate at pH = 5–6. SEM-EDS, FT-IR, and XPS analysis also showed that S2− and Ag+ are bound together as Ag2S in the galena surface. Orbital hybridization of the 4d orbitals of Ag+ with the S2− 3p orbitals occurs during the adsorption process according to density functional theory (DFT) calculations. During the adsorption process, Ag+ undergo charge transfer with S2− in the surface of galena.

The role of temperature on collector adsorption in galena flotation: Implications of seasonal temperature and climate change

This research focuses on studying the effects of the operating temperature and preconditioning time on the adsorption kinetics of sodium diisobutyl dithiophosphinate and sodium isopropyl xanthate collectors on the surface of galena, using contact angle measurements. The results indicate a strong correlation between higher operating water temperature and increased contact angles, suggesting faster adsorption kinetics and heightened hydrophobicity. Statistical analysis underscores the significance of temperature and preconditioning time, both factors being statistically significant. This study delves into the intricate interaction between temperature fluctuations and collector adsorption, contributing to a deeper understanding of flotation processes within the Pb/Cu circuit during seasonal temperature variations.Graphical abstract

Correction: Selective Adsorption Mechanism of Zinc Ions on the Surfaces of Galena and Sphalerite in the Flotation Separation of Pb-Zn

Correction: Selective Adsorption Mechanism of Zinc Ions on the Surfaces of Galena and Sphalerite in the Flotation Separation of Pb-Zn