Presence Of Chalcopyrite Research Articles

The galvanic interaction enhanced the flotation separation of chalcopyrite and galena with humic acid as galena depressant

Depression of galena remains a challenge in the flotation separation of the copper/lead sulfide ores. Current technologies still suffer from considerable drawbacks, primarily due to the utilization of numerous hazardous, expensive, and poorly selective inhibitors. In this work, the influence of galvanic interaction between galena and chalcopyrite on their flotation separation with humic acid as galena depressant was investigated using a combination of the flotation experiment, minerals dissolution experiment, zeta potential, XPS and electrochemical analysis. The results indicated that the recovery of galena rapidly decreased to 34.7% when the conditioning time was extended to 20 min, which was 50% lower than that without chalcopyrite. The dissolved Pb2+ in the pulp increased by 2.2 times in the presence of chalcopyrite. The galvanic interaction between galena and chalcopyrite enhanced the oxidation of galena, leading to an increase in oxysulfide and hydroxide components on the galena surface. The accelerated oxidation of galena is conducive to the humic acid adsorption, achieving an efficient depression of galena flotation at a short conditioning time. This work demonstrated that enhancing the galvanic interaction between galena and chalcopyrite by extending the conditioning time was a viable and eco-friendly approach to achieve the flotation separation of chalcopyrite and galena with humic acid as a depressant.

Impact of deformation and metamorphism on sphalerite chemistry – Element mapping of sphalerite in carbonate-hosted Zn-Pb sulfide deposits of the Kootenay Arc, southern British Columbia, Canada and northeastern Washington, USA

Sphalerites from the Kootenay Arc in British Columbia and Washington State were selected to represent three types of carbonate-hosted massive sulfide deposits, including Mississippi Valley-type (MVT), Irish-type, and fracture-controlled replacement type (FCR). These deposits were variably deformed and metamorphosed during the Cordilleran orogen. Laser ablation inductively coupled plasma mass spectrometric (LA-ICP-MS) analyses of the trace element distributions within the sphalerites are combined with petrography and sulfur isotope analyses to evaluate the influence of primary trace element signatures, along with the variable influence of post-ore metamorphism and deformation on sulfide remobilization and trace element redistribution.Mississippi Valley-type (Josephine orebodies) and Irish-type (Yellowhead orebodies) at Pend Oreille mine are only weakly deformed and recrystallized, so their sulfide minerals commonly retain primary ore textures. The sphalerite from the Irish-type deposit has positive narrow range of δ34S values (17.9–20.5‰, mean 19.2‰), and it is enriched in Ge, Tl and Pb, but depleted in Cd, Mn, and Cu relative to MVT and FCR deposits. Germanium is concentrated in dark-brown acicular-colloform bands where micro-inclusions of a germanium oxide mineral (argutite (GeO2)) and galena have been detected. Other MVT deposits of the Kootenay Arc (Reeves MacDonald, Jersey-Emerald, HB, Jackpot-Lerwick, Duncan) are more deformed and metamorphosed than the Irish-type deposit of the Pend Oreille mine and primary ore textures are only locally preserved. There is a progressive increase in deformation and degree of recrystallization from Reeves MacDonald, located away from intrusions, to deposits within the contact metamorphic aureoles of intrusions (HB, Jersey-Emerald, Jackpot-Lerwick). Sphalerite from the least metamorphosed Reeves MacDonald deposit has high Cd, Ga, Pb, and Tl contents, high Cd/Ge and Ga/In values, and the lowest δ34S values (7.4 to 11.1‰, mean 8.8‰). In contrast, sphalerites from contact metamorphosed HB, Jersey-Emerald and Jackpot-Lerwick deposits have higher δ34S values (13.3 to 28.5‰, mean 19.2‰), are enriched in Mn and Fe, with higher Zn/Cd and Mn/Fe values relative to Reeves MacDonald deposit. These enrichments and fractionations correspond to the breakdown of pyrite and pyrrhotite and the thermal annealing of sphalerite caused by contact metamorphism. Sulfide minerals from the FCR deposit (Abbott-Wagner) are undeformed (except for microfractures) and only weakly recrystallized. Sphalerite from the FCR Abbott-Wagner deposit is enriched in Cu, Ga, In, and Sn as primary source signatures relative to sphalerite from MVT and Irish-type deposits. This reflects the more complex mineral assemblage of galena, sphalerite, pyrite, chalcopyrite, and tetrahedrite in this deposit. The presence of chalcopyrite and tetrahedrite is consistent with a higher-temperature origin of the FCR deposit relative to the lower-temperature MVT and Irish-type deposits.This study demonstrates that the high spatial resolution of in-situ LA-ICP-MS analyses of trace element within sphalerites, in combination with petrography and other analytical techniques (e.g., electron microprobe, secondary ion mass spectrometry, field emission scanning electron microscopy) characterizes the behavior and distribution of trace elements in sphalerite for three deposit types and variable conditions of regional and contact metamorphism. Understanding the effects of metamorphism and deformation on trace elements can be very useful in exploration for deposits rich in critical metals.

Investigations into the flotation of molybdenite in the presence of chalcopyrite using (3S,4S,5S,6R)-3,4,5,6-tetrahydroxyoxane-2-carboxylate acid as a novel selective depressant: An experimental and theoretical perspective

(3S,4S,5S,6R)-3,4,5,6-tetrahydroxyoxane-2-carboxylate (TTC) acid was experimentally and theoretically investigated as a chalcopyrite (CPY) depressant during molybdenite-chalcopyrite (MLT-CPY) beneficiation. It was observed that the adsorption of TTC onto CPY was more than that onto MLT. The zero-point corrected complexation energies for complexes on mineral surfaces was calculated by using M06-2X/6–311++g(d,p)/def2-TZVPP level of theory in gas phase. It was established that Mo(OH)4-∙∙∙FeOH+∙∙∙TTC (S = 1) and FeOH+∙∙∙TTC (S = 0) complexes on MLT and CPY, respectively, of complexation energies of −189.0 kJ/mol and −831.0 kJ/mol, respectively, were the most stable complexes. The analyzed nature of bonding in complexes using Non-Covalent Interaction and Quantum Theory of Atoms in Molecules (QTAIM) suggested that the complexes were governed by traditional hydrogen bonding, as well as covalent, and other non-covalent interactions. Flotation tests carried out using a synthetic mixture of MLT and CPY (1:1) at pH 5.4 ± 0.1 1 in the presence an economical TTC depressant yielded a grade, recovery and separation efficiency of 58.7 %, > 97.6 % and 88.8 %, respectively. Therefore, TTC could be used as a potential depressant of CPY during the flotation of MLT.

Mineralogical and geochemical characteristics of near-vent metalliferous sediments: Implications for hydrothermal processes along the southern Mid-Atlantic ridge (12°S–28°S)

In this study, we present mineralogical and geochemical analyses of 50 unconsolidated submarine surface sediments collected from separate locations within six active hydrothermal fields (Zouyu, Taij, Caifan, Deyin, Xunmei, and Tongguan) along the southern Mid-Atlantic Ridge (SMAR) at 12°S–28°S. The samples consisted of 33 metalliferous sediments (MS) and 17 non-metalliferous sediments (non-MS). The study area was divided into a northern segment that contained the Zouyu, Taij, Caifan, and Deyin hydrothermal fields and a southern segment containing the Xunmei and Tongguan hydrothermal fields. The presence of chalcopyrite, octahedral pyrite, and cubic pyrite without streaks on the surface of the sediments reflected a stable high temperature mineralization environment with a small temperature gradient in the Xunmei hydrothermal field. Cubic pyrite with growth striations co-existing with pentagonal dodecahedon-form pyrite indicated an unstable ore-forming environment with large temperature gradient in the early stage and a more stable ore-forming environment in the late stage in the Tongguan hydrothermal field. Major and trace element geochemistry data indicated that the most important material source for the abiogenic component of the sediments along SMAR 12°S–28°S was hydrothermal materials, the second most important source was lithogenic components, and the third source was elements scavenged from seawater. The Xunmei and Tongguan hydrothermal fields may have recorded phase separation, a process that would have resulted in the formation of two separate hydrothermal fluids, thereby forming two types of sulfide-rich MS with rare earth element (REE) patterns with positive and absent Eu anomalies, respectively. The Si-Fe-Mn oxide-rich MS had positive Eu anomalies, which also indicated that these oxides in sediments were directly precipitated from initial hydrothermal fluids at high temperature. The chlorite-rich MS exhibited nearly flat REE patterns similar to the volcanic material-rich samples and mid-ocean ridge basalt (MORB), which reflected the origin of the hydrothermal alteration of volcanic materials. In the northern segment, most of the MS were derived from plume fall-out Fe oxide particles. In addition, the chlorite-rich MS was likely derived from hydrothermal alteration. In the southern segment, the hydrothermal materials in the MS were primarily derived from the collapse of sulfide-bearing chimneys and Si-Fe-Mn oxide debris directly precipitated from hydrothermal fluids.

Experimental characterization of chalcopyrite ball mill grinding processes in batch and continuous flow processing modes to reduce energy consumption

A mineralogy, rheology, and energy consumption-based experimental characterization of chalcopyrite ball mill grinding processes, in both batch and continuous flow processing modes, is carried out in this work. Accordingly, chalcopyrite ore samples are initially characterized in terms of mineralogical composition, particle size distribution, grindability characteristics, and work index. Next, a rheological characterization of actual and lab-created chalcopyrite mineral-slurries is performed. Finally, an energy consumption-based characterization of several chalcopyrite ball mill grinding processes is performed. The results from the initial mineralogical characterization indicate ore samples featuring 5% chalcopyrite. These results also highlight that 80% of the particles present in the chalcopyrite head ore have a diameter smaller than 1386 μm. In addition, they indicate that the Bond ball mill work index is equal to 15.3 kWh/ton, which corresponds to a mineral with the presence of chalcopyrite. The rheological characterization related results indicate that all actual and lab-created mineral-slurries exhibit a shear thinning rheological behavior. These results also show that, because of the higher number of particle interactions, the slurries’ apparent viscosity increases with the increase in their solids content. Finally, the energy consumption-based characterization results emphasize that energy consumption is more significantly affected by mill speed than by slurry solids content. Indeed, for the same percentage of mass passing through a 200 mesh, it is found that the specific grinding energy decreases with both the increase in slurry solids concentration and the decrease in mill speed. The results obtained in this work are consistent with findings made in previous studies.

Kinetics of Pyrite Oxidation in Simulated Mine Tailings Pond Conditions

Pyrite oxidation is the predominant source of acid mine drainage (AMD), which is one of the severe environmental impacts of mining. AMD destroys flora and fauna in the nearby ecosystem, and it causes grave health problems to the people. To further the understanding and help in the mitigation of AMD, this electrochemical study investigates the effect of the type and concentration of oxidant, and the presence of impurity (chalcopyrite) to the rate of pyrite oxidation, while simulating the conditions in tailings ponds. Open Cell Potential (OCP) and Electrochemical Impedance Spectroscopy (EIS) analysis were done using a three-electrode cell set-up, which is composed of a pyrite rotating disc electrode (RDE), mercury/mercurous sulfate reference electrode in saturated potassium sulfate, and a platinum counter electrode, with a sulfuric acid working electrolyte. Polarization resistance obtained after fitting an electrical circuit to the EIS data was related to the rate of pyrite oxidation, while OCP was used to describe its oxidation mechanism. It was found out that the oxidation of pyrite by ferric ions preferentially occurred rather than by dissolved oxygen. The parameter setting with the lowest relative oxidation rate were: electrolyte with no ferric addition, and with nitrogen purging; and RDE with 10 % chalcopyrite addition. Reaction orders calculated for the effect of ferric ions and dissolved oxygen were equal to 1; but ferric has a higher slope value in the plot. Presence of chalcopyrite in the RDE caused the preferential oxidation of chalcopyrite instead of the pyrite due to their galvanic interaction. To minimize pyrite oxidation, ferric and dissolved oxygen concentration should be minimized, and chalcopyrite impurities should be increased. Keywords: Electrochemical Impedance Spectroscopy, Acid Mine Drainage, Kinetics, Rotating-Disc Electrode, Pyrite

Kinetics and mineralogical analysis of copper dissolution from a bornite/chalcopyrite composite sample in ferric-chloride and methanesulfonic-acid solutions

Ore samples contain a variety of copper-bearing and gangue minerals that affect the leach kinetics. The kinetic behaviour of a natural ore sample (that contained 48.7% bornite and 15.8% chalcopyrite) in a solution of methanesulfonic acid and ferric chloride was studied. The dependence of the reaction kinetics on the acid and oxidant concentration, temperature and particle size was investigated. The reaction activation energy was calculated using two methods, by empirical kinetic equations and by the ‘time-to-a-given-fraction’ method. The shrinking-core-model was fitted according to diffusion through a product layer, and an average apparent activation energy of 79.3 kJ mol−1 was obtained. Three apparent activation energies were obtained by the ‘time-to-a-given-fraction’ method; that for a copper extraction below 20% was 15.6 kJ mol−1 for copper intermediate formation, that between 20% and 50% copper extraction was 42.3 kJ mol−1 associated with sulfur formation and that for dissolution above 50% was 76.5 kJ mol−1 for the final stage when the sulfur layer is covering the entire particle surface. The presence of chalcopyrite in the sample increased the average activation energy by 69% compared with a pure bornite sample. The leach products had different textures; the sulfur formed from chalcopyrite showed a more porous texture than that formed from bornite. These differences in texture are expected to affect the lixiviant access.

Mineralogical Characterization and Gravity Separation of Lean Grade Mixed Copper Ore of Malanjkhand Deposit

An in-depth mineralogical characterization has been carried out to develop a suitable beneficiation process route for a low-grade copper ore. Characterization and preliminary gravity separation studies were undertaken on low-grade Malanjkhand mixed copper ore to remove siliceous gangue and improve the copper grade. The characterization results indicated that the mixed copper ore was of very low grade (0.48% Cu) with a predominant amount of Quartz (74.12%) and with a moderate amount of feldspar and mica. The presence of chalcopyrite and pyrite in minor quantity along with malachite in traces was noted. Preliminary experiments were performed in a Mozley mineral separator by varying flow rate, amplitude and time to discard maximum quantity of liberated quartz. The optimum values of the variables for the efficient pre-concentration were determined based on the separation efficiency. The characterization and preliminary separation studies indicated that gravity-based separation could be opted for the pre-concentration of such mixed copper ore.

Geology, mineralogy, geochemistry and δ34S of sedimentary rock-hosted Au deposits in Song Hien structure, NE Vietnam

The Song Hien rift basin is considered to be one of the most important regions of gold mineralisation in North East Vietnam. A number of gold deposits in the Song Hien rift basin are hosted in Triassic and Devonian sedimentary formations of the basin. The largest among them are the Bo Va, Tham Riem and Khung Khoang deposits. The Bo Va deposit is hosted in carbonaceous sedimentary rocks of Triassic age, whereas the Tham Riem and Khung Khoang deposits are hosted in carbonaceous sedimentary rocks of Devonian ages. Based on the mineral composition of the ores, the deposits can be divided into to two types: (i) pyrite dominated and (ii) pyrite-arsenopyrite dominated. The Khung Khoang is of the first type and the Bo Va and Tham Riem deposits belong to the second type. The isotopic composition of pyrite and arsenopyrite in the Tham Riem deposit however, is close to that for the ores of the Bo Va deposit. The δ34S value for pyrite ranging from −3.7‰ to −7.4‰ and for arsenopyrite ranging from −3.2‰ to 7.4‰. The δ34S of pyrite in the ore from the Khung Khoang deposit however, has a much heavier isotopic composition of +18.9 to +20.2‰. A narrow range of the variation of sulfur isotopic composition of pyrite and arsenopyrite, the presence of visible gold as inclusions, the presence of chalcopyrite, sphalerite and other inclusions in arsenopyrite and pyrite, the large size of the grains of major ore minerals allow us to assume that the primary gold ores of the Bo Va and Tham Riem deposits underwent metamorphic transformations. The absence of arsenic, antimony, mercury and other characteristic elements in the ores of the Khung Khoang deposit, and substantially heavier isotopic composition of sulfur similar to the sulfur isotopic composition of marine sulfates in the Devonian, allow us to assume another source of the ore components, not connected with the Triassic sedimentary rocks of the Song Hien rift.

Review on Mackinawite and Valleriite: Formulae, Localities, Associations and Intergrowths of the Minerals, Mode of Formation and Optical Features in Reflected Light

Investigations of the two minerals concern their chemical compositions and formulae, their intergrowths with other minerals, typical minerals that occur in association with them, their mode of formation within defined types of ore deposits/occurrences and finally also their optical characteristics under reflected light. Mackinawite was observed at 16 localities distributed all over the world from which more than 50 polished sections were available and more than 70 analyses were carried out. Valleriite was found at six localities. Microscopic work was based on more than 40 polished sections and more than 30 analyses. In the literature, mackinawite is reported as a metal excess phase with the formula (Fe, Ni)1+xS and (x ≤ 0.07). Deduced from analyses of this study, mackinawite has a wider compositional range and the formula: (Fe, Ni, Co)1- xS to (Fe, Ni, Co)1+y S, where x=0.00–0.10 and y=0.00–0.10. Therefore, mackinawite may not only occur as a metal excess phase, but also as a metal deficiency one. The high-temperature (max. about 500°C) mineral mackinawite occurs in various types of sulphidic deposits, and is characteristically accompanied with chalcopyrite, pyrrhotite, sometimes pentlandite, pyrite, sphalerite and cubanite and occurs often in oriented intergrowth within chalcopyrite which is always twinned due to inversion. At lower temperature, mackinawite was also formed by the replacement of chalcopyrite (not twinned) and rarely by that of pentlandite and linneite. The formula of valleriite is (Fe, Cu)2S2 • 1.5 [(Mg, Al)1(OH)2]. The analyses of this study show, that valleriite has a wider compositional range and the proposed formula is: (Fe, Cu)2S2 • [(Mg, Fe)1(OH)2] • y [Al(OH)0] with x=1.20 – 2.10 and y=0 – 0.50. Identical with the latter formula, namely that Al and vacancies are constituents of the OH-layer, the formula inverts to: (Fe, Cu)2S2 • [(Mg2+, Fe2+, Al3+ y, ϒy/2)1(OH)2] where x=1.24–2.25 and y=0.00–0.26. Valleriite, formed under mesothermal up to low katathermal conditions, is always a newly-formed mineral. It occurs together with chromite and/or magnetite, mostly along their cracks and fissures, in ultramafic rocks that are serpentinized, but only in the presence of chalcopyrite. Valleriite was also observed as replacer of chalcopyrite. Valleriite decomposes under high-grade metamorphic conditions (e. g. in Outokumpu, Finland).

Geology, mineral chemistry and formation conditions of calc-silicate minerals of Astamal Fe-LREE distal skarn deposit, Eastern Azarbaijan Province, NW Iran

The Astamal Fe-LREE skarn deposit is the largest iron skarn in NW Iran. It is a unique case, as a distal skarn deposit which crops out approximately 600m from the associated Oligo-Miocene granodioritic pluton. This deposit formed in the south-southwest of the pluton where fractures and faults within the Upper Cretaceous volcano-sedimentary host rocks acted as conduits for the mineralizing fluids. The deposit contains three iron ore bodies: southern, northern and eastern. The main mineral assemblage within the ore zones is characterized by magnetite, pyrrhotite and pyrite, with lesser quantities of chalcopyrite, hematite, goethite and limonite. The skarn minerals predominantly comprise garnet, epidote, actinolite, calcite, quartz, clinopyroxene and chlorite (in order of abundance). Retrograde alteration is strongly developed in the skarn zone where most of the garnet has been pervasively altered to secondary minerals (e.g. epidote, calcite and quartz) both in the rims and the cores whereas the majority of the clinopyroxene has been replaced by a hydrous retrograde mineral assemblage (e.g. tremolite, actinolite and chlorite). Garnets with andradite–grossular compositions are the dominant mineral in the skarn zone, which are generally isotropic with a narrow compositional range along the growth lines (Adr94.3–64.5Grs21.9–2.7Alm11.1–0.2). These garnets are Fe-rich and have high Fe/(Fe+Al) ratios (between 0.96 and 0.78). Cu and Ni are enriched in the garnets. This suggests that these elements were enriched in the hydrothermal fluids from which the garnet precipitated. This is supported by the presence of chalcopyrite and Ni-bearing massive magnetite in the study area, which also suggests that Cu and Ni were enriched in the late stage ore-bearing hydrothermal fluids. Clinopyroxene with a hedenbergitic composition is generally homogenous and has particularly high Fe/Fe+Mg ratios (between 0.99 and 0.86) and is poor in TiO2, MnO and Cr2O3. High Zn concentrations were also detected in the clinopyroxenes (up to 1044ppm), despite an absence of significant Zn mineralization (such as sphalerite) in the district. Therefore, it is believed that the proportion of Zn in the hydrothermal fluids decreased significantly from the time of clinopyroxene formation to the period of the sulfide deposition phase. Allanite and LREE-bearing epidotes are the main LREE bearing minerals in this deposit. The epidote is also Fe-rich with high Fe/(Fe+Al) ratios (between 0.32 and 0.44). Due to a lack of replacement texture between both garnet and clinopyroxene and garnet and actinolite (which is formed by alteration of clinopyroxene), it is believed that these two minerals have grown simultaneously and are coexisting minerals. In the Astamal skarn, these minerals can be stable and coexisting at temperatures between 490 and 560°C and LogƒO2=−16 to −31.

Differential gene expression in Acidithiobacillus ferrooxidans LR planktonic and attached cells in the presence of chalcopyrite

Acidithiobacillus ferrooxidans is commonly used in bioleaching operations to recover copper from sulfide ores. It is commonly accepted that A. ferrooxidans attaches to mineral surfaces by means of extracellular polymeric substances (EPS), however the role of type IV pili and tight adherence genes in this process is poorly understood. Genes related to the formation of type IV pili and tight adherence were identified in the genome of the bacterium, and in this work, we show that A. ferrooxidans actively expresses these genes, as demonstrated by quantitative real-time PCR analysis using cells incubated with chalcopyrite for 2 h. Significant differences in gene expression were observed between planktonic and adhered cells, with the level of expression being much greater in planktonic cells. These results might indicate that planktonic cells can actively adhere to the substrate. A bioinformatics analysis of interaction networks of the tight adherence and type IV pilus assembly genes revealed a strong relationship between conjugation systems (tra operon) and regulatory systems (PilR, PilS).

Bioleaching of copper from pre and post thermally activated low grade chalcopyrite contained ball mill spillage

Bioleaching of a low grade chalcopyrite (ball mill spillage material) was tested for copper recovery in shake flasks. The original samples (as received) were thermally activated (600°C, 30 min) to notice the change in physico-chemical and mineralogical characteristics of the host rock and subsequently its effect on copper recovery. A mixed culture of acidophilic chemolithotrophic bacterial consortium predominantly entailing Acidithiobacillus ferrooxidans strain was used for bioleaching studies and optimization of process parameters of both original and thermally activated samples. Mineralogical characterization studies indicated the presence of chalcopyrite, pyrite in the silicate matrix of the granitic rock. Field emission scanning electron microscopy coupled with Energy dispersive spectroscopy (FESEM-EDS) and X-ray Fluorescence (XRF) analysis indicated mostly SiO2. With pH 2, pulp density 10% w/v, inoculum 10% v/v, temperature 30°C, 150 r·min−1, 49% copper could be recovered in 30 days from the finest particle size (−1 + 0.75 mm) of the original spillage sample. Under similar conditions 95% copper could be recovered from the thermally activated sample with the same size fraction in 10 days. The study revealed that thermal activation leads to volume expansion in the rock with the development of cracks, micro and macro pores on its surface, thereby enabling bacterial solution to penetrate more easily into the body, facilitating enhanced copper dissolution.

Ore mineralization in the Miedzianka area (Karkonosze-Izera Massif, the Sudetes, Poland): new information

AbstractThe Miedzianka mining district has been known for ages as a site of polymetallic ore deposits with copper and, later, uranium as the main commodities. Although recently uneconomic and hardly accessible, the Miedzianka ores attract Earth scientists due to the interesting and still controversial details of their ore structure, mineralogy and origin. Our examination of the ore mineralization from the Miedzianka district was based exclusively on samples collected from old mining dumps located in the vicinity of Miedzianka and Ciechanowice, and on samples from the only available outcrop in Przybkowice. In samples from the Miedzianka field, chalcopyrite, pyrite, galena, bornite, chalcocite, digenite, arsenopyrite, magnetite, sphalerite, tetrahedrite-tennantite, bornite, hematite, martite, pyrrhotite, ilmenite, cassiterite and covellite are hosted in quartz-mica schists and in coarse-grained quartz with chlorite. In the Ciechanowice field, the ore mineralization occurs mainly in strongly chloritized amphibolites occasionally intergrown with quartz and, rarely, with carbonates. Other host-rocks are quartz-chlorite schist and quartzites. Microscopic examination revealed the presence of chalcopyrite, pyrite, sphalerite, galena, tetrahedrite-tennantite, bismuthinite, native Bi, arsenopyrite, löllingite, cassiterite, cobaltite, gersdorffite, chalcocite, cassiterite, bornite, covellite, marcasite and pyrrhotite. Moreover, mawsonite and wittichenite were identified for the first time in the district. In barite veins cross-cutting the greenstones and greenschists in Przybkowice, we found previously-known chalcopyrite, chalcocite and galena. The composition of the hydrothermal fluids is suggested to evolved through a series of consecutive systems characterized, in turn, by Ti-Fe-Sn, Fe- As-S, Fe-Co-As-S, Cu-Zn-S and, finally, Cu-Pb-Sb-As-Bi compositions.

Fluid inclusion study of the Wunugetu Cu–Mo deposit, Inner Mongolia, China

Hydrothermal alteration and mineralization at the Wunugetu porphyry Cu–Mo deposit, China, include four stages, i.e., the early stage characterized by quartz, K-feldspar and minor mineralization, followed by a molybdenum mineralization stage associated with potassic alteration, copper mineralization associated with sericitization, and the last Pb–Zn mineralization stage associated with carbonation. Hydrothermal quartz contains three types of fluid inclusions, namely aqueous (W-type), daughter mineral-bearing (S-type) and CO2-rich (C-type) inclusion, with the latter two types absent in the late stage. Fluid inclusions in the early stage display homogenization temperatures above 510°C, with salinities up to 75.8 wt.% NaCl equivalent. The presence of S-type inclusions containing anhydrite and hematite daughter minerals and C-type inclusions indicates an oxidizing, CO2-bearing environment. Fluid inclusions in the Mo- and Cu-mineralization stages yield homogenization temperatures of 342–508°C and 241–336°C, and salinities of 8.6–49.4 and 6.3–35.7 wt.% NaCl equivalent, respectively. The presence of chalcopyrite instead of hematite and anhydrite daughter minerals in S-type inclusions indicates a decreasing of oxygen fugacity. In the late stage, fluid inclusions yield homogenization temperatures of 115–234°C and salinities lower than 12.4 wt.% NaCl equivalent. It is concluded that the early stage fluids were CO2 bearing, magmatic in origin, and characterized by high temperature, high salinity, and high oxygen fugacity. Phase separation occurred during the Mo- and Cu-mineralization stages, resulting in CO2 release, oxygen fugacity decrease and rapid precipitation of sulfides. The late-stage fluids were meteoric in origin and characterized by low temperature, low salinity, and CO2 poor.

Geology of the High Sulfidation Copper Deposits, Monywa Mine, Myanmar

AbstractThe 50 km2 Monywa copper district lies near the Chindwin River within the northward continuation of the Sunda‐Andaman magmatic arc through western Myanmar. There are four deposits; Sabetaung, Sabetaung South, Kyisintaung, and the much larger Letpadaung 7 km to the southeast. Following exploration drilling which began in 1959, production of copper concentrates from a small open pit started at Sabetaung in 1983. Since 1997, when resources totaled 7 million tonnes contained copper in 2 billion tonnes ore, a heap leach–electro‐winning operation has produced over 400,000 t copper cathode from Sabetaung and Sabetaung South. Ore is hosted by mid‐Miocene andesite or dacite porphyry intrusions, and by early mid‐Miocene sandstone and overlying volcaniclastics including eruptive diatreme facies which the porphyries intrude. District‐wide rhyolite dykes and domes with marginal breccias probably post‐date andesite porphyries in the mine area and lack ore‐grade copper. Host rocks to mineralization are altered to phyllic and advanced argillic hydrothermal assemblages within an outer chlorite zone; hypogene alunite is most abundant at Letpadaung and Kyisintaung. Most mineralization is structurally‐controlled with digenite‐chalcocite in breccia dykes, in steeply dipping NE‐trending sheeted veins, and in stockwork and low‐angle sulfide veins. A high‐grade pipe at Sabetaung grades up to 30% Cu, and much of the ore at Sabetaung South is in a NE‐trending zone of mega‐breccia and stockworked sandstone. The hydrothermal alteration, together with replacement quartz, alunite and barite in breccia dykes and veins, the virtual absence of vein quartz, and the presence of chalcopyrite and bornite only as rare veins and as inclusions within the abundant pyrite, indicate that the deposits are high sulfidation. Regional uplift, resistance to erosion and leaching of the altered and mineralized rocks have resulted in porous limonite‐stained leached caps over 200 m thick forming the Letpadaung and Kyisintaung hills. The barren caps pass abruptly downwards at the water table into the highest grade ore at the top of the supergene enrichment zone, within which copper grade, supergene kaolinite and cubic alunite decrease, and pyrite increases with depth; in contrast, marcasite is mostly shallow. Much of the copper to depths exceeding 200 m below the water table occurs as supergene digenite‐chalcocite and minor covellite. Disseminated chalcocite is mostly near‐surface and hence almost certainly supergene. We infer that during prolonged uplift at all four deposits, oxidation of residual pyrite at the water table generated enough acid to leach all the copper from earlier supergene‐enriched ore; below the water table the resulting acid sulfate solutions partly replaced enargite, covellite, chalcopyrite, bornite and pyrite with supergene chalcocite. Undeformed upward‐fining cross‐bedded conglomerates and sands of the ancestral Chindwin River floodplain overlie the margins of the Sabetaung deposits, form a major aquifer up to 40 m thick, and are a potential host for exotic copper mineralization. A mid‐Miocene pluton is inferred to underlie the Monywa deposits, but the possibility of porphyry‐type mineralization within the district is at best highly speculative.

Antioxidant enzyme activity in Acidithiobacillus ferrooxidans LR maintained in contact with chalcopyrite

The total protein content and activity of the enzymes glutathione reductase (GR), superoxide dismutase (SOD) and thioredoxin reductase (TrxR) were evaluated in Acidithiobacillus ferrooxidans LR cells maintained in contact with the metal sulfide chalcopyrite for 1 and 10 days. A significant decrease in total protein content was observed in cells maintained for 10 days in the presence of chalcopyrite, suggesting proteolytic breakdown due to exposure to the metal sulfide. Following 10 days of contact with chalcopyrite, increases in GR, SOD and TrxR activities were detected, suggesting the formation of reactive oxygen species. After ten days, there was a fivefold increase in GR activity, of which, isoenzyme IV represented approximately 82% of the total. An increase in Fe-SOD activity following ten days exposure to chalcopyrite was also determined, as measured on non-denaturing polyacrylamide gels. Also, after 10 days, an approximately 31-fold increase was observed for TrxR activity. The presence of oxidative stress when A. ferrooxidans is in the presence of chalcopyrite could have a negative impact on bioleaching.

The rus Operon Genes Are Differentially Regulated When Acidithiobacillus ferrooxidans LR is Kept in Contact with Metal Sulfides

Acidithiobacillus ferrooxidans is a gram-negative bacterium that obtains energy from the oxidation of ferrous iron or reduced sulfur compounds. In this bacterium, the proteins encoded by the rus operon are involved in electron transfer from Fe(II) to O(2), and the first two proteins in this pathway also participate in the electron transfer pathway from Fe(II) to NAD(P). In this work we analyzed the expression, by real-time PCR, of the eight genes from the rus operon when A. ferrooxidans LR was grown in the presence of iron (control) and then kept in contact with chalcopyrite (CuFeS(2)) and covellite (CuS). A small decrease in rus operon gene expression was observed in the presence of chalcopyrite, while in the presence of covellite the expression of these genes showed a remarkable decrease. These results can be explained by the absence of ferrous iron in covellite. To explain the expression difference observed between the gene cyc1 and the gene rus, we investigated the information content presented at the Translation Initiation Site (TIS) of both genes. cyc1 showed a highly information content (8.4 bits) that can maximize translation, and rus showed a less favorable context (5.5 bits). Our hypothesis is that the energetic metabolism in A. ferrooxidans may be controlled at the transcriptional and posttranscriptional level by different mechanisms.

Leaching of silver sulfide with ferricyanide–cyanide solution

Significantly lower silver extraction than gold has been commonly observed in traditional gold-silver cyanidation process, especially in heap leaching operations. The different mineralogy of gold and silver in the ores is suspected to be the main reason, e.g., the occurrence of low solubility acanthite (Ag 2S) typically results in low overall silver extraction. Leaching of silver sulfide with ferricyanide–cyanide has been investigated with the purpose of increasing the silver extraction. Ferricyanide proved to be an effective oxidant to dissolve silver sulfide in cyanide solution. The main reaction involved under the experimental leaching conditions was determined, indicating the formation of thiocyanate as the sulphur reaction product. The dissolution rate of Ag 2S in ferricyanide–cyanide leaching system (0.5 g/L Fe as ferricyanide) in a rotating disc experiment gives the value of 21 μmol m − 2 s − 1 (0.78 μm/h), much higher than that in aerated cyanide solution (13 μmol m − 2 s − 1 , or 0.38 μm/h). The effect of pH, temperature, ferricyanide and cyanide concentration, and rotating speed on the dissolution rate of Ag 2S were examined. A diffusion-controlled process was confirmed with an activation energy of 6.7 kJ/mol. Study on the leaching kinetics of several mixed sulfide minerals in ferricyanide–cyanide solution shows that the presence of non-silver sulfide minerals may decrease silver extraction from silver sulfide to different extents. A significant decrease in silver extraction is observed in the presence of chalcopyrite (CuFeS 2) and pyrrhotite (Fe 7S 8). It is believed that chalcopyrite and pyrrhotite consume ferricyanide, making it unavailable for silver sulfide leaching.

Simultaneous leaching of a deep-sea manganese nodule and chalcopyrite in hydrochloric acid

Hydrochloric acid leaching of chalcopyrite and a manganese nodule, in combination, was studied using powder samples. Chalcopyrite, which does not dissolve well in HCl, was effectively leached in the presence of a manganese nodule at 3 to 4 M HCl. The rates of dissolution of metal values from the nodule were also enhanced in the presence of chalcopyrite. Dissolution was found to occur through three routes: (1) the galvanic interaction between CuFeS2 and MnO2, (2) the action of the Fe3+/Fe2+ redox couple, and (3) the action of Cl2 gas generated from the MnO2-HCl reaction on CuFeS2. The last route appeared to make the major contribution to the dissolution. The combined leaching of a nodule and chalcopyrite appears to be promising from both technical and economic points of view.