Chalcopyrite Concentrate Research Articles

Catalytic effect of light illumination on bioleaching of chalcopyrite

The influence of visible light exposure on chalcopyrite bioleaching was investigated using Acidithiobacillus ferrooxidans. The results indicated, in both shake-flasks and aerated reactors with 8500-lux light, the dissolved Cu was 91.80% and 23.71% higher, respectively, than that in the controls without light. The catalytic effect was found to increase bioleaching to a certain limit, then plateaued as the initial chalcopyrite concentration increased from 2% to 4.5%. Thus a balanced mineral concentration is highly amenable to bioleaching via offering increased available active sites for light adsorption while eschewing mineral aggregation and screening effects. Using semiconducting chalcopyrite, the light facilitated the reduction of Fe3+ to Fe2+ as metabolic substrates for A.ferrooxidans, leading to better biomass, lower pH and redox potential, which are conducive to chalcopyrite leaching. The light exposure on iron redox cycling was further confirmed by chemical leaching tests using Fe3+, which exhibited higher Fe2+ levels in the light-induced system.

Continuous Bioleaching of Chalcopyritic Concentrate at High Pulp Density

The main objective of the present study was to investigate the continuous bioleaching of chalcopyrite concentrate at a high pulp density by moderate thermophilic microorganisms. Using a flotation concentrate containing 46% chalcopyrite and 23% pyrite, bioleaching tests were carried out at a high pulp density (15%) and temperature of 47°C using a setup consisting of three continuous stirred tank bioreactors in series. A two-level full factorial design of experiments was used to assess the effects of residence time, particle size and acidity of the leaching solution on the copper recovery. From the results of these tests, we concluded that under the best process conditions (d80 = 30 μm, T = 47°C, and acidity of 130 kg/ton) more than 54% of copper was extracted from the concentrate after 7 days. Also, the concentration of copper in the final solution was higher than 20 g/L.

Determination of the Optimum Conditions for Copper Leaching from Chalcopyrite Concentrate Ore Using Taguchi Method

The optimum conditions for the extraction of copper from chalcopyrite concentrate into SO2-saturated water were evaluated using the Taguchi optimization method. High level copper recovery was obtained in an environmentally friendly process that avoids sulfur dioxide emission into the atmosphere because SO2 forming in the roasting is used in the dissolution. Experimental parameters and their ranges were chosen as follows: reaction temperature, 293–333 K; solid-to-liquid ratio, 0.025–0.15 g/mL; roasting time, 30–90 min; roasting temperature, 773–973 K; stirring speed, 400–800 rpm; and reaction time, 10–60 min. The particle size and gas flow rate were 63 µm and 10 cm3/min, respectively. The optimum conditions of the dissolution process were determined to be reaction temperature of 318 K, a solid-to-liquid ratio of 0.025 g mL−1, a roasting time of 75 min, a roasting temperature of 773 K, a stirring speed of 400 rpm, and a reaction time of 30 min. Under optimum conditions, dissolution yield of copper was 91%.

A Moderately Thermophilic Mixed Microbial Culture for Bioleaching of Chalcopyrite Concentrate at High Pulp Density

Three kinds of samples (acid mine drainage, coal mine wastewater, and thermal spring) derived from different sites were collected in China. Thereafter, these samples were combined and then inoculated into a basal salts solution in which different substrates (ferrous sulfate, elemental sulfur, and chalcopyrite) served as energy sources. After that, the mixed cultures growing on different substrates were pooled equally, resulting in a final mixed culture. After being adapted to gradually increasing pulp densities of chalcopyrite concentrate by serial subculturing for more than 2 years, the final culture was able to efficiently leach the chalcopyrite at a pulp density of 20% (wt/vol). At that pulp density, the culture extracted 60.4% of copper from the chalcopyrite in 25 days. The bacterial and archaeal diversities during adaptation were analyzed by denaturing gradient gel electrophoresis and constructing clone libraries of the 16S rRNA gene. The results show that the culture consisted mainly of four species, including Leptospirillum ferriphilum, Acidithiobacillus caldus, Sulfobacillus acidophilus, and Ferroplasma thermophilum, before adapting to a pulp density of 4%. However, L. ferriphilum could not be detected when the pulp density was greater than 4%. Real-time quantitative PCR was employed to monitor the microbial dynamics during bioleaching at a pulp density of 20%. The results show that A. caldus was the predominant species in the initial stage, while S. acidophilus rather than A. caldus became the predominant species in the middle stage. F. thermophilum accounted for the greatest proportion in the final stage.

Biogenesis of Nanoparticles with Potential Applications as Semiconductor from Chalcopyrite Concentrate

Nanostructure forms of semiconductor materials are of great interest. Among these compounds, copper sulfide as a variable stoichiometric composition attracts considerable attention. In the present study, copper sulfide nanoparticles were synthesized biologically from a chalcopyrite concentratemainly containing chalcopyrite (46%) and pyrite (23%). Firstly, the copper contents of the concentrate were bioleached using thermophile bacteria, then the grownFusarium oxysporumwas added to the prepared solution and the biosynthesized nanoparticles collected and their characteristics compared with the product derived from the pure copper sulfate solution. The characterization was performed by UV spectrometry, Fourier Transform Infrared Spectroscopy (FTIR), Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetery (TG), Differential Scanning Calorimetery (DSC), Mass Spectrometery (MS), and Transmission Electron Microscopy (TEM). Finally, it wasproved that the produced nanoparticles had a covellite composition and their size was about 5-40 nm.

Bioleaching and Electrochemical Leaching of a Pyritic Chalcopyrite Concentrate

Moderately thermophilic bioleaching of a pyritic chalcopyrite concentrate was mimicked in an electrochemical vessel. The bioleaching was carried out for 28 days at 45°C with 2.5% (wt/vol) solid content at pH 1.5. Data from the redox potential development was used to program a redox potential controller in an electrochemical vessel to reproduce the same leaching conditions in the absence of microorganisms. Despite precipitation of iron as jarosite and formation of elemental sulphur in the electrochemical experiment, the copper recoveries were almost the same in both experiments.

Substrate Utilisation and Chalcopyrite Concentrate Bioleaching at 60°C in the Presence of Nitrate

In batch cultures, the presence of nitrate inhibited iron (II) oxidation by iron (II)- or tetrathionate-adapted Acidianus (A.) brierleyi and Sulfolobus (S.) metallicus cells and tetrathionate oxidation by iron (II)-adapted A. brierleyi cells. Tetrathionate-adapted cell lines of A. brierleyi and S. metallicus oxidised tetrathionate in the presence of up to 40 mM nitrate but cell numbers were lower than those in uncontaminated tests. The results of the bioleaching tests indicated a possible window of enhanced copper extraction in the presence of 2030 mM nitrate that might be exploited in tank bioleaching. The build up of nitrate above 40 mM in bioleaching solutions must be avoided

Characterization of Cu-SiO2 Composite Synthesized by Hydrogen Reduction of Chalcopyrite Concentrate Followed by Acid Leaching

A Ghatshila chalcopyrite concentrate (average particle size, 50 μm) containing primarily CuFeS2 and SiO2 (Cu 16 pct, Fe 26 pct, S 14 pct, Si 5 pct, and O 33 pct) was reduced by a stream of hydrogen in a horizontal tube furnace at 1323 K (1050 °C), producing a mixture of Cu (26 pct), SiO2, Fe2O3, Fe3O4, Cu2O, and Fe. Subsequent acid leaching with 1 M HCl solution of the reduction product removed all iron oxides and iron, and other impurities too, leaving a Cu (53.3 pct) + SiO2 mixture, with a small percentage of Cu2O in it. This result compares well with the predicted final mixture of Cu (59 pct)-SiO2 based on a mass balance on the starting concentrate. Elemental chemical analyses were done by energy-dispersive X-ray spectroscopy, which were crosschecked by atomic absorption spectroscopy in the majority of cases. The phase identification and microstructural characterization of Cu-SiO2 mixtures were done by X-ray diffraction, Fourier transform infrared spectroscopy, Rietveld analysis, scanning electron microscopy, and high-resolution transmission electron microscopy (HRTEM). It was found that Cu-SiO2 composites were formed in the final product, with a copper grain size of 385 nm.

Leaching of Chalcopyrite Concentrate with Hydrogen Peroxide and Sulfuric Acid in an Autoclave System

In this study, leaching of chalcopyrite concentrate was investigated in an autoclave system using hydrogen peroxide and sulfuric acid. By decomposition of hydrogen peroxide, the active oxygen formed can provide both high oxidation potential and high pressure in a closed vessel for leaching. Preliminary studies showed that hydrogen peroxide can be used as an oxidant instead of oxygen gas in the autoclave. Central composite design (CCD) was used to examine the effects of the experimental parameters on the copper and iron extraction as a response. The proposed model equation using CCD showed good agreement with experimental data, the correlation coefficients R2 for copper and iron being 0.84 and 0.86, respectively. The optimum conditions to obtain the main goal of maximum copper and minimum iron extraction from chalcopyrite were determined as to be sulfuric acid concentration of 2.5 M, hydrogen peroxide concentration of 2.3 M, leaching time of 24 minutes, chalcopyrite amount of 3.17 g (in 50-mL solution), stirring speed of 630 rpm, and leaching temperature of 351 K (78 °C). Under the optimum condition, 76 pct of copper and 9 pct of iron were extracted from chalcopyrite concentrate. Extraction yield results of metals indicate that selective leaching of chalcopyrite can be achieved using hydrogen peroxide and sulfuric acid in an autoclave system.

A research on the Extraction of Metals from Küre Chalcopyrite Concentrate in the Pressure Reactor System

A research on the Extraction of Metals from Küre Chalcopyrite Concentrate in the Pressure Reactor System

COPPER RECOVERY FROM CHALCOPYRITE CONCENTRATE ACID LEACH SOLUTIONS BY ACORGA M5397

Chalcopyrite concentrate from Hajar Mine, Morocco, was leached with nitro-fluosilicic acid leach solution. The pregnant leach solution obtained contained 19.3 g/dm 3 Cu, 18.1 g/dm 3 Fe, 4.5 g/dm 3 Zn and 0.03 g/dm 3 Pb. Copper recovery from this pregnant leach liquor was performed by solvent extrac- tion using Acorga M5397 diluted in Escaid 110. McCabe-Thiele distribution isotherms showed that at pH 1.7 complete and selective copper extraction can be achieved with φo/φa =1.5/1 in 3 stages of extraction. Stripping of the loaded copper by treating the organic phases by a fresh sulphuric acid solution was easily realized.

Re–Os sulfide (chalcopyrite, pyrite and molybdenite) systematics and fluid inclusion study of the Duobaoshan porphyry Cu (Mo) deposit, Heilongjiang Province, China

The Duobaoshan porphyry deposit, located in the northwestern part of the Lesser Hinggan Range, is one of the biggest porphyry Cu (Mo) deposits in the Central Asian orogenic belt in China. The Duobaoshan porphyry deposit occurs in granodiorite and volcanic rocks of the Middle Ordovician Duobaoshan Formation. Six types of veins have been identified in three ore-forming stages as follows: a quartz–potassic feldspar vein in the early ore-forming stage, an early stage quartz–molybdenite vein, late stage quartz–molybdenite and quartz–chalcopyrite–pyrite veins in the middle ore-forming stage, and quartz–pyrite and calcite–quartz veins in the late ore-forming stage. The following four types of fluid inclusions are distinguished from various quartz veins: two-phase aqueous, pure gas phase, CO2-bearing and daughter mineral-bearing inclusions.The ore-forming fluid for the early ore-forming stage belongs to the H2O–CO2–NaCl system, which is characterized by high temperatures (>550°C), intermediate salinities (16.2–18.1wt% NaCl eqv.) and high CO2 content. The ore-forming fluid from the middle ore-forming stage evolved to the H2O–CO2–NaCl system, which is characterized by intermediate to high temperatures (230–450°C) and high/low salinities (0.8 to >65.3wt% NaCl eqv.) and is also rich in CO2 and metals. The ore-forming fluid finally reached cool temperatures (110–200°C), low salinities (3.9–8.4wt% NaCl eqv.) and was CO2-poor. Intensive fluid immiscibility or boiling occurred when the ore-forming fluid with temperatures of 230–450°C and pressures of 10–41MPa ascended to 4.1km, inducing the escape of CO2, depressing the solubility of fluid, and depositing abundant metal sulfides.The total Re and Os concentrations of chalcopyrite and pyrite range from 0.15 to 2.95μg/g and 0.74 to 15.01ng/g, respectively. Analyses of seven chalcopyrite and pyrite samples yielded isochron ages of 482–486Ma, and the model age of one molybdenite sample is 485.6±3.7Ma. The mineralization age of the Duobaoshan deposit is between 482 and 486Ma, and mantle fluid and materials were involved in the mineralization process. The Duobaoshan deposit is a classic porphyry Cu (Mo) deposit that formed in an early Palaeozoic island arc tectonic setting.

Abandoned mine slags analysis by EPMA WDS X-ray mapping

Mining activity on the Iberian Pyritic Belt (Portugal and Spain) started before Phoenician times, became particularly intense during the Roman occupation of the Iberian Peninsula (for gold), and after the industrial revolution (for gold, copper, zinc, lead and sulphur).The commonest ore of this region is a massive polymetalic sulphide accumulation, where pyrite (FeS2) is the main mineral, with variable concentrations of chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), arsenopyrite (FeAsS2), other sulphides and sulfosalts which include minor elements like Mn, Co, Ni, Se, Cd, Sb, Te, Hg and Bi. Some of the main and minor elements of these ores are hazardous and the drainage basins of pollutant source areas often induce health concerns in the resident population. Electron probe microanalysis study followed previous optical and XRD analysis of the slags. The study focused on the identification of phases how sulphide and metallic phases are distributed within the material and infer about leachable elements during weathering. Electron probe X-ray maps show evidences of different behaviour between the elements: Ca and Zn are completely leached; iron is retained in oxyhydroxides, lead and arsenic precipitate as sulphates.Electron probe microanalysis studies are essential to understand complex materials as earth materials. Nevertheless, care is required to a correct interpretation of data and most quantitative compositional data are not trustworthy.

The measurement of chalcopyrite content in rocks and slurries using magnetic resonance

A prototype mineral analyser using magnetic resonance has been configured with two sensors for measurement of the copper sulphide mineral chalcopyrite (CuFeS 2) in ores and slurries. In the first configuration, a sensor was optimised to quantify chalcopyrite content in rock fragments. The detection limit for these measurements was estimated at 15 mg of contained chalcopyrite in rock fragments of mass range of 1.4–3.7 g. The magnetic resonance results correlated with separate quantitative X-ray diffraction measurements of chalcopyrite content. The second configuration was used to quantify chalcopyrite content in mineral slurries. Tests on prepared slurry samples with known chalcopyrite concentration were performed, yielding a standard error of 0.1 wt% across the sample range of 0.5–4.0 wt%. Measurements on a commercial mineral slurry were also performed. The design of an online industrial analyser is discussed with reference to processing slurries with high solid loadings, containing phases such as chalcopyrite and other minerals.

Optimization of the use of carbon paste electrodes (CPE) for electrochemical study of the chalcopyrite

The use of carbon paste electrodes (CPE) of mineral sulfides can be useful for electrochemical studies to overcome problems by using massive ones. Using CPE-chalcopyrite some variables were electrochemically evaluated. These variables were: (i) the atmosphere of preparation (air or argon) of CPE and elapsed time till its use; (ii) scan rate for voltammetric measurements and (iii) chalcopyrite concentration in the CPE. Based on cyclic voltammetry, open-circuit potential and electrochemical impedance results the recommendations are: oxygen-free atmosphere to prepare and kept the CPE until around two ours, scan rates from 10 to 40 mV s-1, and chalcopyrite concentrations > 20%.

Bioleaching of chalcopyrite by mixed culture of moderately thermophilic microorganisms

A mixed culture of moderately thermophilie microorganisms was enriched from acid mine drainages(AMDs) samples collected from several sulphide mines in China, and the bioleaching of chalcopyrite was conducted both in shake flask and bioreactor. The results show that in the shake flask, the mixture can tolerate 50 g/L chalcopyrite after being acclimated to gradually increased concentrations of chalcopyrite. The copper extraction increases obviously in bioleaching of chalcopyrite with moderately thermophilic microorganisms supplemented with 0.4 g/L yeast extract at 180 r/min, 74% copper can be extracted in the pulp of 50 g/L chalcopyrite after 20 d. Compared with copper extractions of mesophilic culture, unacclimated culture and acclimated culture without addition of yeast extract, that of accliniated culture with addition of yeast extract is increased by 53%, 44% and 16%, respectively. In a completely stirred tank reactor, the mass fraction of copper and total iron extraction reach up to 81% and 56%, respectively. The results also indicate that it is necessary to add a large amount of acid to the pulp to extract copper from chalcopyrite effectively.

Archaeal diversity in two thermophilic chalcopyrite bioleaching reactors

This study used a culture-independent molecular approach to investigate the archaeal community composition of thermophilic bioleaching reactors. Two culture samples, MTC-A and MTC-B, grown with different concentrations of chalcopyrite (CuFeS2), a copper sulfidic ore, at a temperature of 78 degrees C and pH 1.6 were studied. Phylogenetic analysis of the 16S rRNA genes revealed that both cultures consisted of Archaea belonging to the Sulfolobales. The 16S rRNA gene clone library of MTC-A grown with 4% (w/v) chalcopyrite was dominated by a unique phylotype related to Sulfolobus shibatae (69% of total clones). The remaining clones were affiliated with Stygiolobus azoricus (11%), Metallosphaera sp. J1 (8%), Acidianus infernus (2%), and a novel phylotype related to Sulfurisphaera ohwakuensis (10%). In contrast, the clones from MTC-B grown with 12% (w/v) chalcopyrite did not appear to contain Sulfolobus shibatae-like organisms. Instead the bioleaching consortium was dominated by clones related to Sulfurisphaera ohwakuensis (73.9% of total clones). The remaining microorganisms detected were similar to those found in MTC-A.

Copper Recovery from Chalcopyrite Concentrate by an Indigenous Acidithiobacillus ferrooxidans in an Air-Lift Bioreactor

In this study, effects of solid concentration, temperature, and initial Fe 2+ concentration on bioleaching of sulfide mineral (chalcopyrite) obtained from Sarcheshmeh Copper Mine in the region of Kerman located in the south of Iran were investigated. A mesophilic iron oxidizing bacterium, Acidithiobacillus ferrooxidans has been isolated from a typical chalcopyrite copper concentrate of the mentioned mine. Bioleaching experiments were carried out in two batch air-lift bioreactors with recycling stream. One reactor contained 2 liters of medium and 10% (v/v) inoculum while in the other reactor, control bioleaching tests were carried out with sterilized concentrate without inoculum by the addition of 40 ml of 0.5% (v/v) formaline in ethanol. The results indicate that the efficiency of copper extraction is dependent on all of the aforementioned variables. In addition, results show that the effects of solid concentration and temperature had more effect compared to the initial Fe 2+ concentration. Maximum copper recovery was achieved 70% at pH=1.5, initial Fe 2+ concentration=7g/L and pulp density = 10% (w/v) in bioreactor, after 10 days.

Mechanism of influence of chloride ions on electrogenerative leaching of sulfide minerals

A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leaching system are similar, and chlorine ion is involved in the electrogenerative leaching process of sulfide minerals directly. The output power increases with the increase of Cl− concentration. The influence on the electrogenerative leaching rate decreases when the Cl− concentration reaches a certain value. The mechanisms of anodic reaction are deduced based on the reasonable hypothesis, and kinetic equations with respect to chlorine ions for each sulfide mineral are obtained. The kinetic equations show that when concentration of Cl− is relatively low, the electrogenerative leaching rates are predicted to have 2/5, 2/7, 1/3 and 1/3 order dependence on Cl− concentration for chalcopyrite concentrate, nickel concentrate, sphalerite and galena. As concentration of Cl− increases, the correlative dependence of electrogenerative leaching rate on concentration of Cl− becomes weak.

Auriferous mineralizations in the Murgul-Artvin-Maradit area northeastern Turkey

The auriferous mineralizations, as the subject of this paper, are placed in the Murgul, Artvin and Maradit surroundings, in the extreme northeastern part of the Turkey. The area is between Black Sea coast to the northwest and Coruh river to the east, northerly bordered by the Georgian - Turkish border and by the Artvin - Fýndýklý line to the south, including spring of the Murguldere. The field is made up of volcanic, volcanic-sedimen- tary, sedimentary and granitoid formations, from Jurassic to Quaternary time. In that period numerous composite petrogenetic complexes had been formed. The oldest is volcanic and volcanic-sedimentary complex including vol- canic rocks of andesitic or intermediate-acidic character, Jurassic in age. They are accompanied by the Iskalka koprusu and Budiyet koprusu copper mineralizations. Gold in this complex has not been studied yet. This rock assemblage is overlain by the acidic rhyolitic and rhyodacitic volcanic and volcanic-sedimentary complex, asso- ciated with large copper deposits and a large number of still not explored or partly investigated copper occur- rences, formed during the Upper Jurassic - Lower Cretaceous. The gold-bearing, related to this complex, is not distinctly developed. According to the present knowledge, precious metals as trace elements are registered in copper deposits in the Murgul surroundings (Anayatak, Cakmakkaya, Aduca dere, Kilise tepe etc), then in the Artvin vicinity (Kuvarshan, Irsa Maden, Sinkot, Seyitler and Umasen). The similar gold and silver appearances are to be expected in the other copper mineralizations, particularly in the Hopa circles (Peronot, Sivrikaya, Kutunit and others). These copper occurrences and deposits are characterized by relatively low gold grades (mostly less than 0.5 ppm) and variable silver contents, with locally high grades (from traces to 180 ppm). However, if large copper reserves are taken into consideration, amounting more than 100 million tons, low grades became signifi- cant; at least 50 tons of gold and several hundred tons of silver is expected to be found. The next petrogenic complex was formed during the Upper Cretaceous - Paleogene time. This is a composite petrogenic unit, en- closing volcanic, volcanic-sedimentary and sedimentary formations. They represent a complete development, beginning from basalts and spilites, throughout andesites, to dacites and rhyolites. The most important rocks in this complex, bearing precious metals, associated with copper, zinc and lead mineralizations, are andesites, part- ly sediments, composed of re-deposited products of andesitic volcanism. In this petrogenic rock assemblage in the related metallogenic stage, two types of gold-bearing mineralizations are distinguished. These are the Akarþen, Hohur sýrtý and Madenkoy base metal deposit near Cayeli, with gold grading up to 11,43 ppm (in Madenkoy) and silver contents ranging from several tens grams per ton of ore up to 241 ppm, including even 350 ppm in Akarþen galena. In the same complex, including the potentially ore-bearing sediments, such as tuffaceous sandstones, contents of 0,11 ppm gold and 2,25 ppm silver have been found. To the next precious metals type belong mineralizations nearby Pehlivan koy near Maradit. They occur in the highly hydrothermally altered andesites, with pyrite and copper minerals. As a special alteration type, adularization is remarkable, indicating the epithermal copper origin and accompanying the gold mineralizations. In only one sample 0,72 ppm gold and 50 ppm silver were detected. These features indicate it as a special mineralization type. The third of auriferous mi- neralizations is found in the Melo dere ravine (Gorge) near Artvin. This is the quartzdiorite, Eocene in age, local- ly bearing high chalcopyrite concentrations, with low gold grades (up to 0,03 ppm), but with higher silver (7,2 ppm). As it is visible from the presented facts, the Murgul - Artvin - Maradit area is considered as very interesting for the gold-bearing copper, zinc and lead mineralizations.