Chalcopyrite Surface Research Articles

The Dissolution Behavior of Pyrite and Chalcopyrite During Low-Temperature Pressure Oxidation: Chalcopyrite Influence on Pyrite Oxidation

The research of this paper was carried out on the low-temperature (100 ± 2 °C) pressure (0.2–0.8 MPa) leaching of pyrite, chalcopyrite and their mixture. According to experiments on chalcopyrite dissolution, increasing the oxygen pressure from 0.2 up to 0.8 MPa had a slight effect on chalcopyrite dissolution. Oxygen pressure and initial sulfuric acid concentration in the range of 10–50 g/L had the greatest positive effect on the pyrite oxidation. The SEM and EDX mappings indicate the chalcopyrite and pyrite surfaces to be passivated by elemental sulfur. The oxidation degree of pyrite in its mixture with chalcopyrite increased significantly from 54.5 up to 80.3% in 0–240 min. The reaction time is relative to the dissolution of the individual mineral, while the dissolution of chalcopyrite remained virtually unchanged. The addition of Cu (II) and Fe (III) ions does not influence pyrite dissolution when chalcopyrite is added in a leaching process, which can be explained by the formation of an electrochemical link between the minerals. The positive effect of chalcopyrite addition is associated with a decreased formation of elemental sulfur on the surface of pyrite. The described method can be used for the hydrometallurgical processing of copper raw materials with increased pyrite content, as well as for the pretreatment of copper concentrates with gold-rich pyrite concentrates to increase the recovery of gold and silver.

The application of KMnO4 in reverse flotation separation of chalcopyrite and talc and its selective depression mechanism

Talc exhibits excellent floatability and, as a major silicate gangue mineral associated with chalcopyrite, significantly obstructs the purification and smelting of chalcopyrite. This study investigates the reverse flotation separation of chalcopyrite and talc using KMnO4 as a depressant and DDA (dodecylamine) as a collector within a reverse flotation system. Single mineral flotation experiments show that after adding KMnO4, the recovery of chalcopyrite in 38–74 μm is only 6.86 %, whereas the recovery of talc in 45–106 μm and 25–45 μm are 93.47 % and 89.25 %, respectively. Further experiments with artificially mixed ores demonstrate that KMnO4 effectively achieves the separation of chalcopyrite and talc. The depression mechanism of KMnO4 on chalcopyrite and talc was analyzed using Zeta potential, contact angle measurement, AFM (atomic force microscopy), FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), and DFT (density functional theory) calculations. Mechanistic analysis indicates that in an alkaline environment, chalcopyrite can undergo a redox reaction with KMnO4, forming hydrophilic hydroxide species (Cu(OH)2, Fe(OH)3) on the chalcopyrite surface, which depresses chalcopyrite flotation. In contrast, the surface properties of talc are relatively stable and difficult to react with KMnO4, which cannot depress the flotation of talc. Therefore, KMnO4 can be used as an efficient and selective depressant for the reverse flotation separation of chalcopyrite and talc.

Lattice defects and surface adsorption properties of gold-bearing chalcopyrite: A theoretical study based on DFT

Chalcopyrite (CuFeS2), as one of the carrier minerals of gold, undergoes significant alterations in lattice and surface properties upon doping with gold impurities. These changes markedly influence its separation and purification techniques, especially flotation. Using Density Functional Theory (DFT) based on first-principles, we analyze the influence of gold impurities on the lattice defects and surface properties of chalcopyrite. We developed an adsorption model using prop-2-yn-1-yl diethylcarbamodithioate (PDEC), a sulfur ester collector with an ethynyl group, on gold-infused chalcopyrite to elucidate the adsorption mechanism. Our findings indicate that the Au atom primarily occupies interstitial sites within the chalcopyrite lattice, resulting in an expanded lattice structure. Despite the doping, the lattice remains a p-type semiconductor with increased conductivity, facilitated by Au 6 s orbitals contributing to impurity levels within the conduction band from 2 to 4 eV. Additionally, there is a marked rise in spin-up electrons, with Integrated |Spin Density| results showing greater electron localization in Cu15Fe16S32Au and Cu16Fe16S32Au compared to ideal chalcopyrite crystal (Cu16Fe16S32). The Au atom exhibits maximum stability when adsorbed onto the S-Fe bonds on chalcopyrite surfaces, primarily forming covalent bonds through electron acceptance from Fe 3d orbitals. The presence of gold impurities decreases the collector's adsorption energy on the chalcopyrite (112) surface. However, PDEC exhibits enhanced adsorption performance relative to Al-DECDT and Z-200, primarily due to the chelation between thiocarbonyl and ethynyl groups of PDEC and the gold-bearing chalcopyrite (112) surface. Electron donation from Fe 4p orbitals of surface to the S 3 s and 3p orbitals of collector forms a sigma bond, while the ethynyl group undergoes hybridization with the Au 5d orbitals from −5 to −2.5 eV, fostering stable electron transfer.

Novel Synergistic Mechanism of Oxalic Acid -CMC at the Solid-Liquid Interface: For Selective Depression of Talc from Chalcopyrite

Flotation separation of chalcopyrite and talc is challenging due to their surface hydrophobicity, requiring a selective depressant for talc to achieve high-quality copper concentrate. This study is the first to use oxalic acid (OA) and carboxymethyl cellulose (CMC) as combined depressants for talc, and investigated the depression mechanism through flotation tests and various analysis techniques. Mixed minerals-flotation results showed that with 60+60 mg/L OA+CMC, talc was strongly depressed (10.16% recovery) with slight chalcopyrite (86.54% recovery) impact. The selective depression effect of OA+CMC was further verified through actual ore flotation experiments. Contact angle and zeta potential test indicated that OA+CMC significantly increased the hydrophobicity difference between talc and chalcopyrite surfaces. Adsorption capacity and atomic force microscope(AFM) results further confirmed that OA promotes CMC adsorption on talc surface, forming a dense CMC layer, whereas CMC adsorption on chalcopyrite was relatively low. Scanning electron microscope energy spectrum spectroscopy (SEM-EDS), fourier transform infrared Spectroscopy(FTIR), and molecular dynamics (MD) results indicate that the synergistic depression mechanism of OA and CMC involves the formation of multiple adsorption layers at the solid-liquid interface, leading to an increased presence of hydrophilic groups on the talc surface, which results in its depression.

The influence of NaCl on xanthate adsorption on chalcopyrite surface and chalcopyrite flotation

Due to freshwater scarcity, mineral flotation plants have been using alternative water resources including seawater together with water recycling resulting in the accumulation of salts in process water. However, how salts affect the adsorption of xanthates on the surfaces of sulphide minerals and subsequent sulphide mineral flotation is unclear. To address the knowledge gap, this study investigated how NaCl affected the adsorption of potassium amyl xanthate (PAX) on chalcopyrite surface and chalcopyrite flotation. Cyclic voltammetry (CV) tests identified that NaCl increased the oxidation of PAX and its adsorption on chalcopyrite surface due to elevated ionic strength and electrical conductivity of water, facilitating charge transfer among PAX, chalcopyrite surface and oxygen. NaCl also increased chalcopyrite surface oxidation to produce more CuS, facilitating the formation of copper-xanthate complexes. Flotation tests identified that the increased adsorption of PAX by NaCl was only translated into improved true flotation of chalcopyrite at a low PAX concentration such as 50 ppm in NaCl solutions with low and medium concentrations (0.1 and 0.7 M, respectively). At a high PAX concentration such as 150 ppm, the coexistence of high concentrations of PAX and NaCl led to strong froth destabilisation, resulting in a dramatic reduction in water recovery and true flotation recovery of chalcopyrite. The findings from this study will be able to guide the flotation plants to maximise mineral flotation by choosing collector dosage based on the ionic strength of process water.

Mechanism of pyrite depression by marine Fe(II)-oxidizing bacteria in seawater flotation

Seawater flotation is a promising technique to reduce environmental and economic loads in mineral processing. This study attempted to depress pyrite, a common gangue sulfide mineral, using two marine iron (Fe) oxidizing bacteria (MFeOB), Thalassospira sp. TF-1 and Mariprofundus sp. E-4, in seawater flotation without pH control; the MFeOB could contribute to hydrophilization of the pyrite surface by oxidation and/or adhesion of bacterial cells. Pyrite or chalcopyrite samples were preconditioned in seawater containing MFeOB for different times (15 min or 30 min). As a result of flotation experiments, the recovery of pyrite preconditioned without MFeOB (i.e., control sample) decreased to 64.2 % after 30 min reaction. The same recovery was observed when pyrite was preconditioned with Thalassospira sp. TF-1, whereas the recovery was successfully decreased to 20.2 % after preconditioning with Mariprofundus sp. E-4 for 30 min. X-ray photoelectron spectroscopy analysis of preconditioned pyrite samples showed no significant difference of Fe-oxidizing compounds between with and without MFeOB reaction, suggesting that the formation of hydrophilic substances such as Fe(OH)3 derived from pyrite oxidation by MFeOB is unlikely to be the main reason for the pyrite depression by Mariprofundus sp. E-4. The adhesion experiment revealed that MFeOB cells could cover the pyrite surface but not the chalcopyrite surface, showing that the hydrophilicity of Mariprofundus sp. E-4 cell caused the pyrite depression. This result suggests that the hydrophilic/hydrophobic properties of bacterial cells are a significant determining factor in pyrite recovery in seawater flotation in the case of MFeOB.

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.

Three novel dithiocarbamate surfactants: Synthesis, DFT calculation and flotation mechanism to chalcopyrite

Three novel dithiocarbamate surfactants including 2-hydroxypropyl diethyldithiocarbamate (HPD-2), 3-hydroxypropyl diethyldithiocarbamate (HPD-3), and 2-(2-hydroxyethoxy)ethyl diethyldithiocarbamate (HED-2) were prepared and characterized by FTIR, 1H/13C NMR and HRMS. They were first employed as collectors to float chalcopyrite. DFT calculations were performed to anticipate the structure–reactivity of the novel dithiocarbamates, revealing that the reaction sites were primarily distributed in CS and OH groups. Compared with HPD-2 and HPD-3, HED-2 possessed a higher chemical reactivity owing to the C-O-C group. Microflotation results indicated that the collecting ability of the three dithiocarbamate collectors towards chalcopyrite followed as HPD-3 > HED-2 > HPD-2. FTIR and XPS demonstrated that HED-2 chemisorbed onto the surface of chalcopyrite through newly generated CuS and CuO bonds.

Quantitative evaluation of the difference in residual collectors in sulfide and non-sulfide flotation processes

In this study, three separate flotation systems were studied to define the residual collectors found in different recycled water for sulfide (xanthate-chalcopyrite), non-sulfide with anionic (NaOL-dolomite) and cationic (DTAB-quartz) collector processes. The adsorption/desorption of collectors and the adsorption morphology were studied by the zeta potential and atomic force microscopy (AFM) measurements, the adsorption energy and configurations were simulated by the density functional theory-based first principal calculations. It was found that butyl xanthate (BX) was adsorbed on chalcopyrite surface with pronounced protrusions by chemisorption, and the residual BX in slurry was 5.79 %. While sodium oleate (NaOL) formed scattered protrusions on dolomite surface by weak adsorption, the residual NaOL in slurry was 30.74 % that reacted with the Ca2+ or Mg2+ cations. The dodecyl trimethyl ammonium bromide (DTAB) adsorbed on quartz surface through hydrophobic aggregations and the residual DTAB in slurry was 16.57 %. This work might provide a guidance for understanding reagent consumption and flotation performance in typical mineral flotation systems.

The depressant-free flotation separation of Cu/Zn sulfide minerals with an environmentally friendly triazine-thiol collector

The depressant-free flotation separation of chalcopyrite from sphalerite in the lower alkaline (pH<10) environment will contribute to reduce carbon emission and benefit the recovery of precious metal minerals. However, it is almost impossible for traditional collectors such as xanthates due to their weak selectivity for chalcopyrite against sphalerite. In this paper, a novel triazine-thiol collector, 2-diethylamine-4-hydroxy-1,3,5-triazine-6-thiol (DEHTT), was first introduced in flotation separation of chalcopyrite from sphalerite. The micro-flotation results elucidated that in the absence of depressants, the recoveries of chalcopyrite and sphalerite from their mixture with 2.0 × 10−6 mol/L DEHTT at pH 9.45 (Na2CO3 as regulator) were 91.83 % and 28.84 %, respectively, while those with sodium isobutyl xanthate (SIBX) were 96.11 % and 78.00 % under the same conditions. In situ AFM and contact angle exhibited that DEHTT assembled on chalcopyrite surface to form lots of aggregates which increased its hydrophobicity, while an insignificant change of sphalerite surface was observed. FTIR, zeta-potential and XPS explored that DEHTT chemisorbed the Cu sites of chalcopyrite surface through its S or O atoms. The specific flotation affinity of DEHTT to chalcopyrite might contribute the cleaner recovery of copper sulfide ores with the lower carbon emission.

Investigation of pullulan polysaccharide as a sphalerite depressant for chalcopyrite separation: Flotation behavior and interfacial adsorption mechanism

The remarkable differences in the metallurgical processes of copper and zinc require their host minerals to be separated as far as possible during beneficiation. For chalcopyrite and sphalerite, the primary host minerals of copper and zinc, their green and efficient separation in the beneficiation stage remains a great challenge. This work is the first to employ environmentally friendly pullulan polysaccharide (PP) as a sphalerite depressant to assist in the concentration of chalcopyrite. Flotation experiments have revealed that PP possesses a selective depression action on sphalerite without having a large influence on the recovery of chalcopyrite. Characterization analysis has revealed that PP can be adsorbed onto chalcopyrite and sphalerite surfaces, but with a different response to subsequent sorption collectors. PP adsorbs to the Zn atoms on sphalerite surfaces via its O atoms in the C−O−H group and thus prevents the adsorption of sodium butyl xanthate (BX). The Fe sites on the chalcopyrite surface can adsorb PP, but this process does not affect the BX adsorption as the Cu sites remain exposed. Hence, PP can enhance the hydrophilicity of sphalerite without interfering with the hydrophobicity of chalcopyrite, resulting in a desirable separation effect. Overall, this work offers a promising scheme for the concentration of chalcopyrite from sphalerite during beneficiation, thereby contributing to the efficient exploitation of copper and zinc resources.

Efficient flotation separation of chalcopyrite from molybdenite and adsorption mechanism by green depressant pyrogallic acid

Chalcopyrite and molybdenite are the primary minerals from which copper and molybdenum are extracted. However, the separation of chalcopyrite and molybdenite is restricted because of their inherent floatability. This study explores the separation effects of the addition of a green depressant, pyrogallic acid (PA), on chalcopyrite and molybdenite. The feasibility of flotation separation was verified by flotations tests with chalcopyrite and molybdenite under weak acid conditions at pH 6. The zeta potential and total organic carbon (TOC) illustrated that PA could have strong chemical adsorption on the surface of chalcopyrite and weak adsorption on the surface of molybdenite. Fourier-transform infrared (FTIR) spectroscopy illustrated that PA had a strong redox reaction at the surface of chalcopyrite. X-ray photoelectron spectroscopy (XPS) results illustrated that the reaction occurred through the generation of Cu/Fe-OH complexes covered on the chalcopyrite surface to reduce the active adsorption sites, which led to a decrease in the collection capacity for chalcopyrite. Moreover, time-of-flight secondary ion mass spectrometry (ToF-SIMS) results showed that the Cu and Fe sites on the surface of chalcopyrite were oxidized by PA. The intensities of FeOH− and CuOH− were found to be enhanced in the fragmentation peaks. Accordingly, a new selective adsorption model of PA on chalcopyrite and molybdenite was proposed.

Study on the selective separation mechanism of tannin acid in chalcopyrite and talc: Insights from adsorption morphology and electrochemical analysis

A key strategy for achieving the selective separation of talc and chalcopyrite is the development of chemical depressants with high solubility and strong selectivity. Tannic acid (TA), a polyphenol found in green plants and has good solubility, contains abundant phenolic hydroxyl groups. Moreover, the adsorption mechanism of TA with chalcopyrite and talc was examined after TA was chosen as the separation depressant for chalcopyrite and talc. Single-mineral flotation test results found that at optimal pH and TA and sodium butyl xanthate (SBX) dosages, the flotation recoveries of talc and chalcopyrite were 9% and 92.17%, respectively, and the difference in recovery between them was 83.17%. Results from real ores and artificially mixed minerals tests also confirmed that TA can achieve selective separation of chalcopyrite and talc. Since chalcopyrite has distinct electrochemical properties, the results of atomic force microscope and electrochemical tests demonstrated that there are significant differences in the adsorption behavior of TA on the surface of chalcopyrite and talc. And the adsorption selectivity of SBX on the chalcopyrite surface is better than that of TA on the chalcopyrite surface, which is an important reason for the selective separation of chalcopyrite and talc.

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.

A brief review on computer simulations of chalcopyrite surfaces: structure and reactivity.

Chalcopyrite, the world's primary copper ore mineral, is abundant in Latin America. Copper extraction offers significant economic and social benefits due to its strategic importance across various industries. However, the hydrometallurgical route, considered more environmentally friendly for processing low-grade chalcopyrite ores, remains challenging, as does its concentration by froth flotation. This limited understanding stems from the poorly understood structure and reactivity of chalcopyrite surfaces. This study reviews recent contributions using density functional theory (DFT) calculations with periodic boundary conditions and slab models to elucidate chalcopyrite surface properties. Our analysis reveals that reconstructed surfaces preferentially expose S atoms at the topmost layer. Furthermore, some studies report the formation of disulfide groups (S22-) on pristine sulfur-terminated surfaces, accompanied by the reduction of Fe3+ to Fe2+, likely due to surface oxidation. Additionally, Fe sites are consistently identified as favourable adsorption locations for both oxygen (O2) and water (H2O) molecules. Finally, the potential of computer modelling for investigating collector-chalcopyrite surface interactions in the context of selective froth flotation is discussed, highlighting the need for further research in this area.

A new insight into the mechanism of MNB-assisted flotation of copper: A link between chalcopyrite and its-bearing bulk ore

The present study systematically explores the relationship between chalcopyrite mono-mineral and copper-bearing ore flotation in the presence and absence of micro- and nano-bubbles (MNBs). Ultrafine bubbles were generated through a cavitation mechanism, and their stability, size, and zeta potential were monitored over a period of 0–25 days. Micro-flotation and batch rougher kinetic flotation experiments were carried out with and without ultrafine bubbles using a modified Hallimond tube and 2.5 L Denver® flotation cell, respectively. The results showed that the presence of MNBs improved the recovery of chalcopyrite mono-mineral and its ore by 24.5 % and 7 %, respectively. Furthermore, the adsorption behavior of sodium isopropyl xanthate (SIPX) collector at various concentrations was analyzed in the presence and absence of stable MNBs using UV–visible spectroscopy, FTIR analysis and kinetic models. The adsorption studies supported the micro-flotation findings, demonstrating that the presence of MNBs not only boosted collector adsorption on the chalcopyrite surface (by an average of 73.8 %) but also improved the adsorption kinetics (by 69.44 %). The sorption kinetics followed the pseudo 2nd order model in the presence of MNBs, while in the absence of MNBs, both pseudo 1st order and pseudo 2nd order models were observed. The sorption of SIPX onto chalcopyrite was identified as a chemisorption process in the presence of MNBs, whereas it was a physicochemical sorption in the absence of MNBs.

Study on Chalcopyrite Dissolution Mechanism and Bioleaching Community Behavior Based on Pulp Concentration Gradient at 6 °C

Low-temperature bioleaching is relevant to the recovery of metals in alpine mines, but its development has been constrained by low bioleaching rates at high pulp concentrations. To this end, the bioleaching effect of the microbial community after the domestication of pulp concentration at 6 °C was studied. Domestication improved the bioleaching rate of copper. Environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD), and electrochemical measurements revealed that the domestication process aggravated the corrosion of the chalcopyrite surface by accelerating its dissolution reaction. High-throughput sequencing technology indicated that Acidithiobacillus spp., Leptospirillum spp., and Acidiphilium spp. were the major lineages of the domesticated microbial community. The analysis of the microbial community revealed that domestication changed the microbial structure, enhancing the adaptability of the microbial community to pulp concentrations and acidic conditions. This study uncovered the mechanism by which domestication enhanced the bioleaching efficiency of the microbial community at low temperatures.

Effects of biodegradable dispersants on the separation flotation of chalcopyrite and serpentine

The presence of serpentine slime coating on the chalcopyrite surfaces severely affects the chalcopyrite floatability. In this study, three biodegradable polymers, namely polyaspartic acid (PASP), polyepoxy succinic acid (PESA), and hydrolyzed polymaleic (HPMA) were used as dispersants to disperse the chalcopyrite and serpentine particles. The micro-flotation experiments demonstrated that the application of dispersants in the flotation effectively reduced the negative impact of serpentine over a wide pH range, restoring the recovery rate of chalcopyrite to about 85%. The XPS analysis revealed that the dispersants could be adsorbed onto the mineral surfaces through the binding of carboxyl groups with the magnesium or copper sites. As a result, the surface potentials of serpentine changed from positive to negative, while that of the chalcopyrite became even more negative, resulting in a strong electrostatic repulsion between them, which effectively eliminated the covering of the serpentine on the chalcopyrite surface. The AFM force measurements indicate a weak interaction of the polycarboxylic acids dispersants with the surface of chalcopyrite. Consequently, the adsorption of dispersants on the chalcopyrite surface has an insignificant impact on the subsequent adsorption of collectors, which is further supported by the adhesion force measurements between the air bubble and mineral surfaces. Therefore, the application of polycarboxylic acid dispersants in the flotation significantly enhanced the floatability of chalcopyrite in the presence of the serpentine fines.

Selectively improves chalcopyrite hydrophobicity to achieve copper and arsenic separation: Interfacial reaction and application research

The efficient separation of chalcopyrite and arsenopyrite is significant for preventing and controlling arsenic pollution. Herein, sodium diisobutyl dithiophosphate (SDD) selectively improves chalcopyrite hydrophobicity to achieve copper and arsenic separation in low alkali. The flotation test results show that SDD is stronger than butyl xanthate and ethyl thiocarbamate regarding selective collection ability. SDD accurately separates chalcopyrite and arsenopyrite under low alkali conditions. Frontier orbit analysis shows that the feedback π and positive σ bonds between SDD and arsenopyrite surface are the weakest among the three collectors. Surface wettability, adsorption capacity, FTIR, XPS, and adsorption simulation calculations reveal more detailed collecting mechanisms. Analysis shows that SDD can selectively improve the hydrophobicity of the chalcopyrite surface. The above results were attributed to SDD breaking the CaOH+ adsorption barrier on the chalcopyrite surface. On the contrary, the interaction between SDD and arsenopyrite is weak, resulting in SDD being unable to break through the cover of CaOH+ on the surface of arsenopyrite.