Gold In Copper Research Articles

Improving the technology of copper-zinc ore beneficiation of a Uralian-type pyrite deposit

Introduction and research objective. Copper-zinc ore of pyrite deposits of the Uralian type are refractory. Difficulties in beneficiation are due to their material composition: fine coarseness and emulsion impregnation of ore minerals in each other, a large amount of flotation-active pyrite, a high content of finely dispersed and submicroscopic gold in sulfides, etc. In the course of pyrite ore processing at dressing mills, 83–91% of copper and 10–45% of gold are extracted into copper concentrates, and 46–78% of zinc and 5–15% of gold are extracted into zinc concentrates. Increasing the process performance of pyrite deposit ore processing is a promising and urgent task. Methods of research included copper-zinc pyrite ore material composition study through quantitative chemical analysis, chemical phase analysis for the forms of copper, zinc, gold and silver compounds, and mineralogical analysis. Technological studies were carried out by flotation and gravity methods using a centrifugal concentrator and a concentration table. Conclusions. In the course of pyrite deposit copper-zinc ore beneficiation at the dressing mill, the effect of circulating concentration of gold in the coarse copper concentrate regrinding cycle was established. The results of studies on the centrifugal concentration of gold in a centrifugal concentrator with further secondary cleaning of its heavy fraction on a concentration table show the possibility of obtaining a gravity product with a mass fraction of gold up to 200 g/t under its operational extraction up to 29%. It was noted that the integrated flotation-gravity technology for copper-zinc ore beneficiation will increase the through extraction of gold into marketable mineral products by more than 1.5%. The use of a combination of butyl potassium xanthate and FRIM-2920 reagent-collector in the copper-zinc pyrite ore flotation technology contributes to increased extraction of copper and gold into copper concentrate by 0.87% and 3.22%, respectively, and zinc into zinc concentrate by 0,4%. Increasing the pulp temperature in the zinc flotation cycle to 40–45 °C and returning the control zinc flotation concentrate and tailings from the first cleaning flotation of zinc to the II main zinc flotation allows increasing the mass fraction of zinc in the zinc concentrate from 48.5 to 51.1% under a simultaneous increase in the extraction of zinc into zinc concentrate from 62.6 to 65.6%.

Metal requirements for road-based electromobility transitions in Sweden

This research investigated the metal requirements for electrifying Swedish cars and heavy-duty trucks and refueling infrastructure. We assessed vehicle and infrastructure metal use given four cornerstone scenarios: battery electric vehicles and chargers, conductive and inductive electric road systems, and fuel-cell vehicles, besides an internal combustion engine scenario. Twenty-seven metals were evaluated. To our knowledge, this study presents a first attempt to develop a detailed inventory of prevailing and prospective charging infrastructures. Our study estimated total metal requirement at 7400–9600 kt and infrastructure share at 6%–25% (200–2400 kt). Infrastructure requires about 15% of gold, 30%–40% of silver and copper, and 40%–60% of molybdenum. Results revealed that the following metal flows contribute the most to long-term resource scarcities: rhodium in fossil-fueled vehicles; gold in electric vehicles; palladium and gold in conductive and copper and palladium in inductive electric road systems; as well as platinum in fuel cells.

Study of inter-diffusion of gold in copper in the presence of single layer graphene

• Graphene acts as a diffusion barrier for interdiffusion of Au in Cu upto 220°C. • From 240°C to 280°C, grain boundary diffusion is dominant in Au/Gr/Cu. • Slower ion beam mixing is observed in Au/Gr/Cu compared to Au/Cu sample. • Disorder is more in graphene upon annealing and amorphization upon irradiation. Rutherford backscattering spectrometry (RBS) has been used to examine the inter-diffusion behaviour in Au thin films (∼30 nm) deposited on CVD grown monolayer Graphene on copper (Au/Gr/Cu) with reference to gold film deposited on copper (Au/Cu), under thermal annealing and ion beam irradiation processes. Graphene is acting as a diffusion barrier in Au/Gr/Cu upto 220 °C for the inter-diffusion of Au in Cu in thermal annealing process, while interdiffusion occurs below 200 °C in Au/Cu. In high temperature regime, bulk diffusion mechanism is dominant in Au/Cu system whereas grain boundary diffusion is dominant in Au/Gr/Cu system. The dominant grain boundary diffusion in Au/Gr/Cu indicates that grain boundary defects in graphene play a major role in inter-diffusion process. Upon 9 MeV Si 6+ ion irradiation, there is no ion beam mixing upto 5 × 10 15 ions/cm 2 and at the ion fluence of 3 × 10 16 ions/cm 2 , ion beam mixing is observed in both Au/Cu and Au/Gr/Cu samples, with lower ion beam mixing rate and mixing efficiency for Au/Gr/Cu sample. This implies that graphene interlayer can prevent ion beam mixing to a certain extent due to its impermeable nature. The blue shift of Raman spectroscopy peaks G and 2D and the splitting of G-peak from graphene barrier layer signifies the compressive strain in Au deposited and thermally annealed Gr/Cu samples. Even though interlayer graphene can reduce the interdiffusion in Au/Cu system modestly, it becomes disordered with the formation of sp 3 carbon bonds with increase in annealing temperatures and ion fluences, thereby loosing its impermeable nature.

Effect of tetrathionate on thiosulfate leaching of gold in copper–ammonia system

AbstractGold thiosulfate leaching have the best prospects for industrial application; however, the effect of polythionate on this system is complicated. Effect of tetrathionate on thiosulfate leaching of gold in a copper–ammonia system over a prolonged period of time was studied in detail. The results show that the gold concentration is higher in the tetrathionate‐added solution at the end of experiment. Scanning electron microscope and surface‐enhanced Raman spectroscopy were utilized to study the passive layer on gold surface. The results show that the blue material adsorbed on gold surface in tetrathionate system is copper hydroxide species. Besides that, the UV‐visible spectrophotometer absorbance peak of Cu(II) complex in tetrathionate‐added solution locates at higher wavelength.

Thermodynamic modeling of native formation of Au–Ag–Cu–Hg solid solutions

It is difficult to interpret the significance of some types of gold alloys without thermodynamic data describing the Au–Ag–Cu–Hg systems. Literature data on the content of copper and mercury in native gold and silver and that of silver and gold in native copper and mercury from gold deposits of different genesis were collected and analyzed. Activity coefficients of the solid solutions in Au–Ag–Cu–Hg quaternary system were estimated. The corresponding calculation module prepared for a “Selektor-C” software package allows calculation of the composition of quaternary solid solutions depending on the change in T,P,X-parameters. Ore formation scenarios were modeled for two objects: i) “hydrothermal” – on the example of formation of quaternary solid solutions in hydrothermal conditions at the Aitik Au–Ag–Cu porphyry deposit (Sweden); ii) “hydrothermal-hypergene” – on the example of formation of Au–Cu intermetallics at the Wheaton Creek placer deposit (Canada). The approach described in our work can be used as an additional tool for the analysis of the genesis of gold deposits and estimation of formation conditions of natural solid solutions of noble metals that are in many cases the main carriers of ore components.

Comparison and statistical evaluation of neutron activation methodologies for the determination of gold in copper concentrate

Uncertainty, the most important characteristic of an analytical result, has been evaluated using a bottom-up approach during NAA determination of Au in copper concentrate. The sampling constant has been calculated to arrive at a representative sample size of copper concentrate.

A rapid ICP-OES strategy for determination of gold and silver in blister copper by nitric acid digestion

A rapid strategy for the analysis of gold and silver in blister copper by inductively coupled plasma optical emission spectrometry (ICP-OES) was firstly proposed. Nitric acid was used to digest blister copper instead of commonly used sulfuric acid. This prevented forming the salt of copper sulfate in the filtration process when the volume of the mixture is very small. Thus, the time of filtration was saved. After filtrating, aqua regia was used to digest the residue and acidize the filter liquor. Two parts of gotten solution were directly determined by ICP-OES. The cycle of analysis was shortened compared with sulfuric acid-fire assay. The proposed method was successfully applied to determine gold and silver in blister copper, and the results were in good agreement with those obtained by lead fire assay.

Rapid analysis of gold and sliver in blister copper by nitric acid digestion prior to determination by atomic absorption spectrometry

A rapid method for the analysis of gold and sliver in blister copper by atomic absorption spectrometry was proposed. Nitric acid was used to digest blister copper instead of commonly used sulfuric acid. This avoided forming the salt of copper sulfate in the filtration process when the volume of the mixture is very small. Thus, the time of filtration was saved. After filtrating, aqua regia was used to digest the residue and acidize the filter liquor. Two parts of gotten solution were directly determined by atomic absorption spectrometry. The cycle of analysis was shortened compared with sulfuric acid-fire assay. The proposed method was successfully applied to determine gold and sliver in blister copper, and the results were in good agreement with those obtained by lead fire assay.

The effect of different collectors on recovery of copper and precious metals of the ore body Tenka 3

This work presents a part of technological testing that were conducted in order to define the optimum conditions of flotation concentration of the ore from the deposit Tenka 3 - North Mining District, Majdanpek copper mine. Provided description refers to testing the effect of collectors NaIPX, 3418 and AP5500 as well as the pH value of pulp to the certain technical indicators (recovery of copper and precious metals) of the rough flotation process. It was found that generally the best recoveries of copper and gold in the basic copper concentrate are obtained using a combination of collectors 3418 and AP5500, while the best silver recovery in the basic copper concentrate is obtained using the sodium isopropyl xanthate. In addition, higher recoveries of gold and silver were obtained at lower pH value of pulp, while, on the other hand, a clear dependence of copper recovery on pH value was not observed in tested pH range (10.0 to 11.5).

Interatomic interaction in solid solutions of gold in copper

It is supposed that not only pairwise but also many-particle interaction exists between metal atoms in binary solid solutions. Therefore, the mixing energy in the solid solution V i that is determined from the data on the parameters of short-range order in terms of the model of pairwise interaction has no direct physical sense and proves to be dependent on the concentration of the solute c:V i = V i (c). Only the pair potential h i = V i (0) for impurity atoms to approach each other in the lattice of solvent, which is determined by extrapolation of the V i (c) dependence to zero concentration, is physically meaningful. The potential h i can be used for the calculation of the Wagner interaction parameter and first-order enthalpy parameter. These considerations have been applied to solid solutions of gold in copper. For the Wagner parameter of interaction e Au Au and enthalpy parameter η Au Au in copper-based alloys at 800 K, a satisfactory agreement of the theory and experiment has been obtained.

The role of ligands and oxidants in thiosulfate leaching of gold

The widely used cyanidation technology is not applicable to some gold ores due to economic or technical reasons when the cyanidation gives very low gold extractions. Despite the fact that the gold mining industry accounts for only 13% of total cyanide consumption there is growing public concern over the use of toxic cyanide for gold extraction. Many researchers have identified that thiosulfate leaching is the most likely alternative to cyanidation due to nontoxicity, low cost and other benefits. This article describes the current information on stoichiometric relationships, equilibria, reaction rates and mechanisms related to anodic or chemical oxidation of gold in thiosulfate, ammoniacal thiosulfate and ammoniacal copper(II) thiosulfate solutions in the presence or absence of oxygen.

Kinetics and Mechanism of High-Temperature Oxidation in Air of Au - Cu Alloy

We have used thermogravimetry to study the kinetics of high-temperature (up to 800 °C) oxidation of the alloy 58.3 mass% Au - 41.7 mass% Cu with isothermal heating of the specimens. Using petrographic analysis of the oxide layers, we determined the reaction products. We have shown that up to 200 °C, the indicated alloy is not oxidized at all. More rapid oxidation of the alloy is observed at temperatures above 400 °C. Up to 500 °C, an inner layer consisting of Cu2O predominates in the two-layer scale on the alloy, while the outer CuO layer has a significantly smaller thickness. At 600 °C, the upper layer of scale contains Cu2O while the lower layer contains Cu2O and gold. At higher temperatures, all the way up to 800 °C, the scale is two-layer as before but its upper layer contains CuO while its lower layer contains Cu2O and small gold rods distributed in that oxide. Thus we have established three oxidation regions characterized by different scale phase compositions and different mechanisms for the process, mainly due to transition from an ordered state of the alloy (intermetallic AuCu3) to a completely disordered solid solution of gold in copper. We used the Arrhenius equation to calculate the apparent activation energy for oxidation: E1 = 20.4 kJ/mole for the temperature range 400–500 °C and E2 = 9.5 kJ/mole for 600–800 °C.

ICP-AES による粗銅中の金の定量分析

ICP-AES による粗銅中の金の定量分析

Determination of gold and silver in copper concentrates, using k0 based neutron activation analysis

Procedures for the determination of gold and silver in copper concentrates, using k0 based neutron activation analysis, were developed and tested. The effects of gamma-ray self attenuation, neutron self-shielding and spectral interference were considered; precision, accuracy, and detection limits were studied by repeated analysis of copper concentrate internal reference materials. The analytical results have shown good precision and satisfactory accuracy in concordance with the detection limit and range of concentration.

Diffusion bonding and brazing of high purity copper for linear collider accelerator structures

Diffusion bonding and brazing of high purity copper were investigated to develop procedures for joining precision machined copper components for the Next Linear Collider (NLC). Diffusion bonds were made over a range of temperatures from 400 \ifmmode^\circ\else\textdegree\fi{}C to 1000 \ifmmode^\circ\else\textdegree\fi{}C, under two different loading conditions [3.45 kPa (0.5 psi) and 3.45 MPa (500 psi)], and on two different diamond machined surface finishes. Brazes were made using pure silver, pure gold, and gold-nickel alloys, and different heating rates produced by both radiation and induction heating. Braze materials were applied by both physical vapor deposition (PVD) and conventional braze alloy shims. Results of the diffusion bonding experiments showed that bond strengths very near that of the copper base metal could be made at bonding temperatures of 700 \ifmmode^\circ\else\textdegree\fi{}C or higher at 3.45 MPa bonding pressure. At lower temperatures, only partial strength diffusion bonds could be made. At low bonding pressures (3.45 kPa), full strength bonds were made at temperatures of 800 \ifmmode^\circ\else\textdegree\fi{}C and higher, while no bonding (zero strength) was observed at temperatures of 700 \ifmmode^\circ\else\textdegree\fi{}C and lower. Observations of the fracture surfaces of the diffusion bonded samples showed the effects of surface finish on the bonding mechanism. These observations clearly indicate that bonding began by point asperity contact, and flatter surfaces resulted in a higher percentage of bonded area under similar bonding conditions. Results of the brazing experiments indicated that pure silver worked very well for brazing under both conventional and high heating rate scenarios. Similarly, pure silver brazed well for both the PVD layers and the braze alloy shims. The gold and gold-containing brazes had problems, mainly due to the high diffusivity of gold in copper. These problems led to the necessity of overdriving the temperature to ensure melting, the presence of porosity in the joint, and very wide braze joints. Based on the overall findings of this study, a two-step joining method is proposed for fabricating the NLC structures. The structure would be assembled with pure silver braze inserts using a self-aligning step joint design, then the assembly would be vacuum diffusion bonded at 700 \ifmmode^\circ\else\textdegree\fi{}C and 3.45 MPa pressure to seal the critical inner portion of the assembly. Finally, during the same furnace cycle, the temperature would be increased to 800 \ifmmode^\circ\else\textdegree\fi{}C in order to react the silver with the copper to form a liquid braze alloy that would join and seal the outer portion of the cells together.

Extraction–atomic absorption spectrometric method for the determination of the platinum group elements and gold in copper–nickel ores using an autoclave sample decomposition technique

An ETAAS method was developed to determine the platinum group elements and gold in copper–nickel ores using a single sample. It is based on an approach involving interconnected consideration of the main components of analytical procedure (autoclave decomposition of sample; collective extractive preconcentration of metals with a mixture of alkylaniline hydrochloride and petroleum sulfides; and atomic absorption spectrometric analysis of the extract). The concentrations of elements determined in standard reference materials (lode and impregnation copper–nickel sulfide ores) were found to be in accordance with the certified values, within experimental error. The relative standard deviation varied between 2 and 17% at 0.05–10 mg kg–1 element concentrations. The determination limits were 0.001–0.06 mg kg–1 for a 5 g sample and an extract volume of 5 ml.

Grain-boundary diffusion and segregation of gold in copper: Investigation in the type-B and type-C kinetic regimes.

Grain-boundary (GB) impurity diffusion of Au in Cu has been investigated by the radiotracer serial-sectioning technique using the $^{195}\mathrm{Au}$ isotope with high specific activity. Measurements in the temperature ranges 618 to 1036 K and 450 to 526 K were carried out in Harrison's type-B and type-C regimes, respectively. In the type-B regime, the product P=${\mathit{sD}}_{\mathrm{GB}}$\ensuremath{\delta} was determined (s being the segregation factor, ${\mathit{D}}_{\mathrm{GB}}$ the GB-diffusion coefficient, \ensuremath{\delta} the GB width), while in the type-C regime ${\mathit{D}}_{\mathrm{GB}}$ values were measured directly. Combining the obtained P and ${\mathit{D}}_{\mathrm{GB}}$ values and assuming \ensuremath{\delta}=0.5 nm, the Au GB-segregation factor was evaluated. From the temperature dependence of s, the segregation enthalpy ${\mathit{H}}_{\mathit{s}}$=-9.7 kJ ${\mathrm{mol}}^{\mathrm{\ensuremath{-}}1}$ has been obtained. GB self-diffusion in Cu in the type-B regime has also been studied by the same experimental technique using the tracer $^{64}\mathrm{Cu}$. The obtained ${\mathit{D}}_{\mathrm{GB}}$=P/\ensuremath{\delta} values for self-diffusion are systematically larger than ${\mathit{D}}_{\mathrm{GB}}$ values for Au in Cu, whereas for lattice diffusion the opposite interrelation holds. This observation is discussed in terms of a trapping of Au atoms during impurity GB diffusion.

Simulation of point defects and threshold displacements in pure Cu and a dilute Cu-Au alloy.

The influence of solute atoms on point-defect properties and defect generation by radiation damage in alloys is known to be important, and hence it is desirable to understand their effect on the basic mechanisms involved. Most computer modeling of these phenomena has only considered pure metals, but as part of a project to investigate displacement cascades in alloys, we have simulated dilute solutions of gold (Au) in copper (Cu), treating this as a «model» for a heavy, oversized solute alloy system. In the present paper, modified many-body interatomic potentials for the Cu-Au system are described that are suitable for modeling high-energy atomic collisions. The properties of point defects in pure copper and the dilute alloy, including solute-defect binding energies, are presented

Reductive coprecipitation and extraction as separation methods for the determination of gold in copper concentrates by AAS and ICP-AES

Simple methods for the determination of gold in copper concentrates are presented. Two separation procedures for gold are proposed. The first preconcentration procedure is based on the reductive coprecipitation of Au using part of the matrix copper as collector. The second implies selective quantitative extraction of Au using the extraction system 0.2 mol/l HCl/IBMK. Flame AAS or ICP-AES are used as instrumental methods and permit the determination of 0.1–50 μg/g gold with a relative standard deviation of 3–12%.

Gold-rich porphyry systems in the Maricunga Belt, northern Chile

The Maricunga belt is a linear metallogenic unit defined by at least 14 zones of gold and/or silver mineralization between latitudes 26 degrees and 28 degrees S in the Andean Cordillera of northern Chile. After 10 years of exploration, three precious metal deposits are in production, two more have proven reserves, and others are being drilled. Total geologic reserves are 420 metric tons of gold and about 14,000 metric tons of silver divided between intrusion-hosted porphyry-type deposits and volcanic-hosted epithermal deposits of high sulfidation, acid sulfate type.Precious metal mineralization is related to a belt of Miocene volcanic rocks, most of which constitute a series of large compound stratovolcanoes of calc-alkaline composition. The volcanic rocks overlie unconformably and largely conceal an igneous and sedimentary basement of Paleozoic and Mesozoic age. Volcanic rocks and contained alteration and mineralization are subdivided on the basis of K-Ar dating into partly overlapping, western early Miocene (24-20 Ma) and eastern middle Miocene (14-13 Ma) subbelts. High-angle reverse faulting occurred between these two epochs in response to regional compression induced by subduction zone flattening. A northwest alignment is also prominent in the belt as reflected by the strike of several components of the alteration and mineralization zones.Nine zones of porphyry-type mineralization have been discovered in the Maricunga belt, where they are present in both western and eastern subbelts. The porphyry-type mineralization was generated beneath andesitic-(dacitic) stratovolcanoes, which were dissected more extensively in the western than in the eastern subbelt. Volcanic rocks were intruded by isolated, composite porphyry stocks which are dioritic in the eastern subbelt but include quartz dioritic phases in the western subbelt. Weakly porphyritic microdiorite and associated intrusion breccia are prominent stock components. Minor inter- to late mineralization hydrothermal breccias are commonly present.Gold-copper mineralization is believed to have been introduced with K silicate alteration, which is well preserved only at the Amalia, Refugio, and Casale Hill (Aldebaran) prospects. K silicate alteration is overprinted and commonly obliterated by sericite-clay-chlorite assemblages of intermediate argillic type. Much of the gold is present in quartz stockworks. Iron oxides, both early magnetite and late hematite, constitute 5 to 10 vol percent of mineralized zones. Sulfides are dominated completely by pyrite but include minor chalcopyrite and trace bornite and molybdenite. Supergene leaching of copper is developed to various degrees, but enrichment is developed only incipiently.Several porphyry-type stockworks are overlain by pyrite- and alunite-rich advanced argillic alteration, which carries barite, native sulfur, enargite, and at La Pepa, high-grade, vein-type gold mineralization of high sulfidation, epithermal type. The quartz stockworks and advanced argillic caps are telescoped at Marte, Valy, Santa Cecilia, and La Pepa but are separated by a chloritized zone transected by a swarm of gold-poor, polymetallic veins with quartz-alunite selvages at Aldebaran.Marte and Lobo are rich in gold (1.43 and 1.6 ppm) and poor in copper (0.05 and 0.12%) and molydenum (46 and approximately 10 ppm), and may be designated as porphyry gold deposits. However, gold contents are lower (0.6-1 ppm) and hypogene copper contents probably higher at Refugio and Casale Hill. Zinc tends to occur as a geochemical halo to the Au-Cu-Mo mineralization, which is always deficient in silver (<0.1 ppm). Arsenic and mercury are enriched in the advanced argillic caps, and along with lead, are also weakly anomalous at Marte in the underlying, shallow-level quartz stockwork.The depth of erosion of Maricunga porphyry-type systems is believed to decrease from the K silicate zones exposed at Refugio and in the Casale Hill sector at Aldebaran, through Marte, Valy, Santa Cecilia, and La Pepa where remnants of advanced argillic caps are present, to the highest, mercury-rich part of the Cathedral Peak sector at Aldebaran and zones higher than and west of Marte which comprise advanced argillic alteration rich in native sulfur. Reconstruction of the porphyry systems suggests that gold-bearing quartz stockworks were generated 600 to 1,000 m beneath paleosurfaces.Gold-rich porphyry mineralization in the Maricunga belt is closely comparable to that in the Philippines because of the association with dioritic to quartz dioritic porphyry stocks intruded into andesitic-(dacitic) stratovolcanoes, the widespread distribution of intermediate argillic assemblages as partial or complete overprints to K silicate alteration, the abundance of hypogene iron oxides with ore, and the common preservation of advanced argillic caps. The Maricunga porphyry-type mineralization stands in contrast to the porphyry deposits else-where in northern Chile, which are associated with more felsic intrusions lacking coeval volcanic rocks, contain large volumes of sericitized rocks, lack abundant ore-related iron oxides, are molybdenum rich, gold poor, and more than ten times larger, and include major supergene enrichment blankets. However, both the gold-rich Maricunga belt and the molybdenum-rich deposits in northern Chile are underlain by thick continental crust, whereas the Philippine copper-gold province is in an island-arc setting.