Copper Sulfide Minerals Research Articles

Limitations of conventional sulphidisation in restoring the floatability of oxidised chalcocite

The secondary copper sulphide mineral, chalcocite, is the second most important copper mineral and its flotation is significantly affected by the surface oxidation. There is scarcity of reports on sulphidisation of oxidised chalcocite and literature suggests that the conventional sulphidisation experiences difficulties in activating sulphides that are prone to oxidation. Thus the objective of this study was to understand the sulphidisation of chalcocite, the copper sulphide most prone to surface oxidation. To achieve this, surface analysis by Cryogenic X-ray photoelectron spectroscopy, Cyclic Voltammetry measurements and flotation tests were adopted. It was found that the lower flotation recovery of the oxidised chalcocite after sulphidisation at 0.10 V vs. standard hydrogen electrode was attributed to partial sulphidisation, 36.2%, of the Cu(II) oxidation species to form the desired Cu(I)-S product, while 62.8% of the species remained unsulphidised. It was revealed that all the Cu(II) oxidation species on chalcocite were sulphidised to the desired Cu(I)-S product at the lower potential of −0.20 V. Intriguingly, the flotation recovery was even lower than that obtained at 0.10 V. The limited improvement in flotation even though the surface was fully sulphidised was attributed to the high electrochemical activity and re-oxidation of the Cu(I)-S product formed.

Sedimentology, Metallographic Characteristics and Geodynamic Evolution of the Merija Copper Deposit (Marginal Folds Basin, Eastern High Atlas, Morocco)

The Merija copper deposit is located in the Marginal Folds of the Moroccan Eastern High Atlas. It is a stratiform deposit hosted in sandstone-conglomerate formations of the Infra-Cenomanian, consisting of copper carbonate and sulphide mineralization (malachite, azurite, traces of chalcopyrite, chalcocite, and covellite). This mineralization exhibits different forms: dissemination in the sandstone-conglomerate host rocks and fillings of centimetric veins, sometimes with calcite. Moreover, microscopic examination shows that the mineralization is disseminated in the carbonate matrix, filling of the inter-granular spaces of the sandstone-conglomeratic material. The mineralogical association is composed of: a primary paragenesis with chalcopyrite ، a secondary cementation paragenesis with chalcocite and covellite and a secondary oxidation paragenesis with malachite. This latter is the most dominant mineral presenting a micro-fibrous texture surrounding the sulphides of the primary and secondary paragenesis, composed of chalcopyrite, chalcocite and covelite. It is associated with a quartz-calcite gangue. The copper mineralization at Merija is heterogeneously distributed within the surrounding sandstone-conglomerate formation due to the diversity of paleocurrents carrying the leached copper. The rich paleocurrents trends S, SW, and SE, whereas the poor ones present an N and NW directions. These paleocurrents are derived from a fluvio-deltaic channel system that controlled sedimentary deposition in the area during the Infra-Cenomanian. This sedimentary type mineralization is probably related to a process of alteration and deposition of detrital materials loaded with copper minerals and derived from a protore copper-bearing. This alteration process gave rise to the malachite and azurite mineralization resulting from the replacement phenomenon of chalcopyrite, chalcocite and covellite.

The Challenges and Prospects of Recovering Fine Copper Sulfides from Tailings Using Different Flotation Techniques: A Review

Flotation is a common mineral processing method used to upgrade copper sulfide ores; in this method, copper sulfide mineral particles are concentrated in froth, and associated gangue minerals are separated as tailings. However, a significant amount of copper is lost into tailings during the processing; therefore, tailings can be considered secondary resources or future deposits of copper. Particle–bubble collision efficiency and particle–bubble aggregate stability determines the recovery of target particles; this attachment efficiency plays a vital role in the selectivity process. The presence of fine particles in the flotation circuit is because of excessive grinding, which is to achieve a higher degree of liberation. Complex sulfide ores of markedly low grade further necessitate excessive grinding to achieve the maximum degree of liberation. In the flotation process, fine particles due to their small mass and momentum are unable to collide with rising bubbles, and their rate of flotation is very slow, further lowering the recovery of target minerals. This collision efficiency mainly depends on the particle–bubble size ratio and the concentration of particles present in the pulp. To overcome this problem and to maintain a favorable particle–bubble size ratio, different techniques have been employed by researchers to enhance particle–bubble collision efficiency either by increasing particle size or by decreasing bubble size. In this article, the mechanism of tailing loss is discussed in detail. In addition, flotation methods for fine particles recovery such as microbubble flotation, column flotation, nanobubble flotation, polymer flocculation, shear flocculation, oil agglomeration, and carrier flotation are reviewed, and their applications and limitations are discussed in detail.

Efficiency of using ozone for extraction of metals from mineral raw materials

The paper summarizes the results of studies on the use of ozone for the extraction of non-ferrous, rare and noble metals from ores, beneficiation concentrates and technogenic raw materials identified from world scientific publications and in patent literature since the early 20th century. Ozone is a strong oxidizing agent with an oxidizing potential 1.5 times higher than the potential of chlorine in an acidic environment. Even refractory metals and minerals dissolve with ozone. Metal extraction from mineral raw materials using ozone does not contaminate processed products or generate any hazardous waste. The paper presents a significant number of studies on the use of ozone to dissolve gold and other noble metals in mineral acids showing an increase in the extraction of metals into the solution. The cyanide and thiourea leaching of gold from mineral raw materials with the replacement of oxygen with ozone was investigated. The paper provides the results of the vat and heap leaching of non-ferrous and noble metals using ozone obtained by air or oxygen irradiation with ultraviolet light, in particular with the use of photoelectrochemical treatment. These results were used as a basis for patenting new technologies. The effectiveness of ozone used in the flotation concentration of mineral raw materials, purification and detoxification of solutions and solid products of metallurgical processing, regeneration of other oxidants, metal extraction from process solutions was evaluated. The results of studies on using ozone for the vat leaching of metals from refractory sulfide ores and sulfide beneficiation concentrates in an acid solution, and the study of the ozone-assisted oxidation kinetics of copper, iron, zinc, and molybdenum sulfide minerals are summarized. The paper provides and analyzes the results of using ozone in a combination with other oxidants – hydrogen peroxide and iron (III) ions – for metal extraction from sulfide mineral raw materials in a sulfuric acid. According to the results of most of the studies carried out, it can be concluded that the use of ozone is effective for metal extraction from mineral raw materials as it improves process performance (metal extraction into the solution, selectivity of metal extraction from complex raw materials), and reduces processing time.

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

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

Depression Effect of Thioglycolic Acid (TGA) on Flotation Separation of Molybdenite from Copper Sulfides with different Collectors: An Experimental and Theoretical Study

AbstractIn the present study, the depression effect of thioglycolic acid (TGA) on chalcopyrite and pyrite in the presence of different collectors, including potassium ethyl xanthate (PEX), sodium isopropyl xanthate (SIPX), and mercaptobenzothiazole (MBT) in the flotation separation of molybdenite from copper and iron sulfide minerals was evaluated by micro‐flotation and bench‐scale flotation experiments. Surface characterization and adsorption mechanism were investigated by the density functional theory (DFT) method. The flotation experiment results demonstrated that the depression effect of TGA depends on the type of collector applied in the previous stages. DFT calculation provided strong evidence for the results of experiments. It was found that both chalcopyrite and pyrite were effectively depressed in the selective flotation of molybdenite from copper and iron sulfides by TGA when PEX was used as the collector in the bulk flotation stage. It was also found that the use of MBT causes effective flotation of chalcopyrite and molybdenite in the bulk flotation stage, however, its removal from the mineral surface by TGA was not as convenient as PEX.

Nitric Acid Dissolution of Tennantite, Chalcopyrite and Sphalerite in the Presence of Fe (III) Ions and FeS2.

This paper describes the nitric acid dissolution process of natural minerals such as tennantite, chalcopyrite and sphalerite, with the addition of Fe (III) ions and FeS2. These minerals are typical for the ores of the Ural deposits. The effect of temperature, nitric acid concentration, time, additions of Fe (III) ions and FeS2 was studied. The highest dissolution degree of sulfide minerals (more than 90%) was observed at a nitric acid concentration of 6 mol/dm3, an experiment time of 60 min, a temperature of 80 °C, a concentration of Fe (III) ions of 16.5 g/dm3, and an addition of FeS2 to the total mass minerals at 1.2:1 ratio. The most significant factors in the break-down of minerals were the nitric acid concentration, the concentration of Fe (III) ions and the amount of FeS2. Simultaneous addition of Fe (III) ions and FeS2 had the greatest effect on the leaching process. It was also established that FeS2 can be an alternative catalytic surface for copper sulfide minerals during nitric acid leaching. This helps to reduce the influence of the passivation layer of elemental sulfur due to the galvanic linkage formed between the minerals, which was confirmed by SEM-EDX.

Application of double-pulse laser-induced breakdown spectroscopy (DP-LIBS), Fourier transform infrared micro-spectroscopy and Raman microscopy for the characterization of copper-sulfides.

The combined application of the structure sensitive techniques Fourier transform infrared μ-spectroscopy and Raman microscopy in conjunction with different approaches of laser-induced breakdown spectroscopy (LIBS) including the two-color double pulse (DP-LIBS) have been applied towards the characterization of whole ore copper-sulfide minerals. Discrete information from the surface of the whole ore minerals that lead to the establishment of infrared marker bands and from the surface of bioleached samples that allow the monitoring of jarosite and biofilm formation are provided by FTIR mapping experiments. Raman data can provide information related to the type of the mineral and of the secondary minerals formed on the surface of the ore. Of the four different LIBS approaches applied towards the characterization of the composition of the whole ore minerals, the DP-LIBS shows the highest sensitivity with increasing signals for both the Fe and Cu metals in the whole ore samples.

Copper sulfides leaching assisted by acidic seawater-based media: Ionic strength and mechanism

• Acidic seawater-based media (ASM) could be utilized as an alternative of industrial freshwater. • ASM improve leaching kinetics of copper sulfide via reaction activation energy and ORP . • The mineral dissolution was sensitive to the ionic type and its concentration of ASM. • Effect of ionic ratio (e.g. ferric to ferrous) on ORP and activation energy was significant. The seawater is purified or pre-treated to obtain the acidic seawater-based media (ASM), which has been gradually utilized in copper hydrometallurgical industries, resulting in desirable copper recovery efficiency. In the chemical/bio leaching of chalcocite, chalcopyrite, and other low-grade copper sulfide minerals, the ASM is proved to have a good catalytic effect and it could potentially intervene the leaching reaction and interface condition. In this regard, to further understand the effects of ASM, this paper critically discussed the pivotal ions (ferric/ferrous ions, cupric/cuprous ions, elemental sulfur, passivation ions, silver catalytic ions, etc.) and its compounds, regeneration behavior in the leaching reaction. The current studies tightly related to the effects of these pivotal ions on the redox potential, reaction activation energy, and leaching kinetics were also comparatively analyzed. The tolerances of microorganisms and reactions to ASM were carefully explored. Relied on the previous studies and reviewing in this paper, it inferred that as an efficient, potential alternative of freshwater, the ASM could provide a good expected possibility to accelerate copper sulfide leaching, especially in areas with scarce water resources.

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

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

Thermal analysis of Indonesian copper sulphide

The development of extracting hydrometallurgical process for copper sulphide mineral becomes one of the promising fields, not only for the copper production but also for the production of metal by-products. The advantage of the thermal analysis is to get the phase form of the minerals on a certain temperature. With this result, the chosen metal can be selectively extracted. The goal of this study is to understand the thermal reaction of the copper sulphide as the basic data to develop a process flowsheet of extracting copper and other important metals from the copper concentrates by using an alternative new hydrometallurgy process to increase the value of the minerals. The thermal behaviour was investigated by simultaneous thermal analysis consisting of differential scanning calorimetry (DSC) in combination with thermo gravimetry (TG) and fourier transform infrared (FTIR) spectroscopy. Samples were pre-treated by roasting at the several temperature transitions and subsequently characterized by XRD and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS).

Biofilm Formation Is Crucial for Efficient Copper Bioleaching From Bornite Under Mesophilic Conditions: Unveiling the Lifestyle and Catalytic Role of Sulfur-Oxidizing Bacteria.

Biofilm formation within the process of bioleaching of copper sulfides is a relevant aspect of iron- and sulfur-oxidizing acidophilic microorganisms as it represents their lifestyle in the actual heap/dump mining industry. Here, we used biofilm flow cell chambers to establish laminar regimes and compare them with turbulent conditions to evaluate biofilm formation and mineralogic dynamics through QEMSCAN and SEM-EDS during bioleaching of primary copper sulfide minerals at 30°C. We found that laminar regimes triggered the buildup of biofilm using Leptospirillum spp. and Acidithiobacillus thiooxidans (inoculation ratio 3:1) at a cell concentration of 106 cells/g mineral on bornite (Cu5FeS4) but not for chalcopyrite (CuFeS2). Conversely, biofilm did not occur on any of the tested minerals under turbulent conditions. Inoculating the bacterial community with ferric iron (Fe3+) under shaking conditions resulted in rapid copper recovery from bornite, leaching 40% of the Cu content after 10 days of cultivation. The addition of ferrous iron (Fe2+) instead promoted Cu recovery of 30% at day 48, clearly delaying the leaching process. More efficiently, the biofilm-forming laminar regime almost doubled the leached copper amount (54%) after 32 days. In-depth inspection of the microbiologic dynamics showed that bacteria developing biofilm on the surface of bornite corresponded mainly to At. Thiooxidans, while Leptospirillum spp. were detected in planktonic form, highlighting the role of biofilm buildup as a means for the bioleaching of primary sulfides. We finally propose a mechanism for bornite bioleaching during biofilm formation where sulfur regeneration to sulfuric acid by the sulfur-oxidizing microorganisms is crucial to prevent iron precipitation for efficient copper recovery.

Analysis of the Dynamics of Rougher Cells on the Basis of Phenomenological Models and Discrete Event Simulation Framework

Due to the increase in the amount of copper sulphide minerals processed through concentration processes and the need to improve the efficiency of these production processes, the development of theoretical models is making an important contribution to generating a better understanding of their dynamics, making it possible to identify the optimal conditions for the recovery of minerals, the impact of the independent variables in the responses, and the sensitivity of the recovery to variations in both the input variables and the operational parameters. This paper proposes a method for modeling, sensitizing, and optimizing the mineral recovery in rougher cells using a discrete event simulation (DES) framework and the fitting of analytical models on the basis of operational data from a concentration pilot plant. A sensitivity analysis was performed for low, medium, and high levels of the operative variables and/or parameters. The outcomes of the modeling indicate that the optimum mineral recovery is reached at medium levels of the flow rate of gas, bubble size, turbulence dissipation rate, surface tension, Reynolds number of bubble, bubble–particle contact angle, superficial gas velocity and gas hold-up in the froth zone. Additionally, the optimal response is reached at maximum levels of particle size and density and at minimum levels of bubble speed, fluid kinematic viscosity and fluid density in the sampled range. Finally, the recovery has an asymptotic behavior over time; however, the optimum recovery depends on an economic analysis, examining the marginalization of the response over time in an operational context.

Dissolution kinetics and solubilities of copper sulfides in cyanide and hydrogen peroxide leaching: Applications to increase selective extractions

Accurate quantification of secondary and primary sulfide minerals is fundamental for resource evaluation, ore processing, and long-term sustainability of mining operations. In addition to visual mapping and automated mineral quantification, chemical analysis can also be harnessed to characterize the mineralogy of ore deposits. By evaluating the conditions in which certain minerals can be selectively dissolved from others, a chemical evaluation could provide geochemical speciation data of low-abundance minerals, such as copper/iron sulfides present in low-grade copper ores. The selective dissolution of copper sulfide minerals is, however, understudied. Here, we evaluate the use of potential selective dissolution conditions to differentiate supergene copper sulfides from hypogene copper sulfides. By characterizing the dissolution kinetics of chalcocite, covellite, bornite, enargite, chalcopyrite, and pyrite concentrates, we found that alkaline cyanidation (and not hydrogen peroxide or acid leaching in the presence of oxidizing agents) selectively dissolves supergene copper sulfides, which can be applied in a sequential extraction scheme to estimate the sulfide mineralogy of tailings samples. Cyanide completely dissolved chalcocite and covellite within 5–15 min, whereas dissolution in acid oxidative media only partially dissolved copper sulfides. Pyrite, chalcopyrite, enargite, and bornite under 0.5% KCN leaching (1 mg/mL) for 10 min showed approximately 1, 10, 30, and 40% of copper recovery, respectively. Cyanide leaching applied in sequential extractions of porphyry copper tailings samples from the Piuquenes impoundment, La Andina, Chile, improved the selective dissolution of secondary sulfides compared to a previously proposed hydrogen peroxide dissolution method, thus allowing their differentiation from primary sulfide minerals. The selective leaching of supergene sulfides by cyanidation provides a cheap and efficient method to estimate the copper sulfide mineralogy in copper ores, facilitating the sustainability and resource evaluation of mining operations.

Rare Crucible from Medieval Karelian Hillfort: Mineralogical Fingerprints of Functional Use

A rare crucible with an unusually large volume and a pot-shaped bottom was excavated at the Tiversk hillfort (late 13–14th century—1411 AD) in the North-Western Ladoga region (Russia). ICP-MS data showed that the crucible might be attributed to local technical ceramics. Because of its specific volume and shape, which are not typical for crucibles used in non-ferrous metallurgy in medieval Karelia, earlier it had been attributed to the technical ceramics used for the cementation of iron. The present research has revealed tin bronze metal alloy along with copper sulfide minerals recorded on the crucible walls, suggesting it might have been used in non-ferrous metal working. Thermal treatment of the crucible at temperatures above 1050 °C is evidenced by the heterogeneous composition of quartz, the thermal breakdown of biotite, recorded in the temper of the ceramic fabric, and Raman spectra characteristics of hematite.

Understanding the hetero-aggregation mechanism among sulfide and oxide mineral particles driven by bifunctional surfactants: Intensification flotation of oxide minerals

To promote the separation and enrichment efficiency of oxide minerals from the sulfide-oxide ores through froth flotation has become a challenging issue. In this paper, the driving role of S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dibutyl-dithiocarbamate (HABTC) in facilitating the aggregation of copper sulfide and oxide minerals particles was explored through atomic force microscope (AFM) force measurements and the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory calculation. AFM imaging, contact angle measurement and surface energy computation showed that the self-assembly of HABTC on chalcopyrite and malachite improved the hydrophobicity of their surfaces and reduced their interaction free energies. AFM force measurements observed that the “jump in” attachment occurred at 8.6 ~ 12.5 nm during the approaching chalcopyrite towards malachite in HABTC solution, which was mainly attributed to the hydrophobic interaction between them. And the adhesion force between them in HABTC solution was much larger than that in OHA solution, being contributed to HABTC’s bridging role driven by its uncoordinated dithiocarbamate or hydroxamate groups to bond with the surface copper atoms of different minerals. The two-step hetero-aggregation among chalcopyrite and malachite particles sequentially-induced by HABTC’s nonpolar and bipolar groups built a carrier flotation platform where the floatability of malachite particles was significantly promoted by chalcopyrite particles with a superior hydrophobicity, resulting in an improved flotation recovery of malachite.

A Comparative Kinetic Study of Chalcopyrite Leaching Using Alternative Oxidants in Methanesulfonic Acid System

ABSTRACT Methanesulfonic acid was proven to be an alternative lixiviant for copper leaching from chalcopyrite with hydrogen peroxide as an oxidant. Two alternative oxidants, dichromate and nitrate, were studied for the copper dissolution from chalcopyrite, a refractory copper sulfide mineral. During chalcopyrite leaching tests, both oxidants achieved the copper extraction above 90% in 30 g/L methanesulfonic acid at 75oC. The activation energies in dichromate and nitrate leaching systems were 23 and 43 kJ/mol, classified as mass transfer and chemical reaction-controlled mechanism, respectively. The XRD analysis of a leached residue showed a formation of K-Cr-jarosite from methanesulfonic acid-dichromate system. Methanesulfonic acid with nitrate leaching system could be the most effective and sustainable for chalcopyrite leaching based on the comparative investigation.

Hydrophobic agglomeration flotation of oxidized digenite fine particles induced by Na2S and butyl xanthate

Secondary copper sulfide mineral fine particles are easily oxidized, and their effective recovery by froth flotation is extremely challenging. This study investigated the roles of sodium sulfide (Na2S) and sodium butyl xanthate (SBX) in the hydrophobic agglomeration flotation of oxidized digenite fine particles. The microflotation experiments of the study showed that the simultaneous addition of Na2S and SBX is beneficial for improving the floatability of heavily oxidized digenite fine particles. In addition, the recovery at pH 7.0 was apparently higher than that of the unoxidized digenite fine particles, indicating that hydrophobic agglomeration of digenite fine particles may occur. The results of the zeta potential measurements, X-ray photoelectron spectroscopy analyses, and contact angle measurements suggested that negatively charged hydrogen sulfide ion and xanthate ion respectively hydrolyzed from Na2S and SBX adsorbed on the surface of digenite. Moreover, they significantly decrease the amount of hydrophilic copper sulfate and oxides/hydroxides on the surface, thus improving the surface hydrophobic degree of digenite. The results of the optical microscopy analysis, particle size analysis, and extended Derjaguin–Landau–Verwey–Overbeek theory calculations provided strong evidence for the roles of Na2S and SBX in promoting the hydrophobic agglomeration of the digenite fine particles. After treatment with Na2S and SBX, the total interaction energies between the digenite fine particles were negative, indicating that the strong hydrophobic attractive forces promote the formation of large-sized agglomerates, enabling the digenite fine particles to be more easily captured by bubbles than those without the treatment. Therefore, effective recovery of heavily oxidized digenite fine particles can be realized by the hydrophobic agglomeration flotation technology induced by Na2S and SBX.

Development of a grinding model based on flotation performance

Usually, the concentration of minerals is carried out with a set of flotation and grinding units. Most of the modeling strategies for the flotation and grinding stages have followed separate developmental paths. This paper presents a strategy based on using flotation studies to model flotation and grinding via an integrated approach. The methodology, which is an approximate method that allows one to study of the effects of grinding on flotation circuits, is applied to a copper sulfide mineral with appropriate results. Given its nature, the application of this method will help preliminary studies on the design, improvement, and simulation of flotation circuits. The major advantages of this method are its simplicity and low cost. Thus, the main contribution of this work is a new strategy to model grinding for integration into the modeling of flotation circuits. This new strategy can be extended to other concentration technologies that include grinding.

Flotation performance, structure–activity relationship and adsorption mechanism of a newly-synthesized collector for copper sulfide minerals in Gacun polymetallic ore

This study investigated the flotation performance, structure–activity relationship and adsorption mechanism of a newly-synthesized collector N-ethyl-N'-isopropoxycarbonyl thiourea (EICTU) for copper sulfide minerals in Gacun polymetallic ore. The bench-scale flotation test indicated that EICTU exhibited superior flotation performance to the copper sulfide minerals compared with conventional butyl xanthate (BX) and O-isopropyl-N-ethyl thionocarbamate (IPETC) collectors. The results of comparative test showed that among the three collectors EICTU had the strongest collecting ability and optimal selectivity for Cu2+/chalcopyrite. The structure–activity relationship study based on density functional theory (DFT) calculation supported the above conclusion. The adsorption mechanism analysis indicated that EICTU adsorption on copper sulfide mineral surfaces was a chemical process by separately generating normal covalent bond between carbonyl S atom and Cu atom and back donation covalent bond between carbonyl O atom and Cu atom, which was confirmed by FTIR spectrum analysis results. The lattice impurity iron is unfavorable to EICTU adsorption on tetrahedrite surface while zinc, arsenic and silver impurities had little effect. EICTU presents excellent collecting power and selectivity for copper sulfide minerals and thus it has great potential to be applied industrially.