• Economic and Environmental Geology
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• v.31 no.6
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• pp.463-472
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• 1998

The survey was carried out in order to delineate the occurrence of ore deposits and the mineralized characteristics in the Estancia de la Virgen area through the 1:2,000 scaled geological mapping and topographic measuring surveys. Gold-silver mineralization is in the fault block developed between the San Agustin Fault and Cabanas Fault. It is associated with ore bearing quartz veins controlled by the fault structure. The contents of Au and Ag range from traces up to 72 g/t and 180 g/t respectively. According to traversing the outcrops, the quartz veins are traced by 0.5 Km trended to north and south. In those extended part, they continue for 1,000 m intermittently. Gold-silver mineralization could be divided into three stages. In the first stage, pyrite, galena, sphalerite, and chalcopyrite were formed with the primary silver and gold associated with galena and copper sulfides respectively. In the second stage, Cu-Bi-Au-Ag bearing sulfides such as chalcocite, covellite, and linarite are formed and usually deposited on the cataclastic fractures of galena and/or chalcopyrite. In the third stage, both the carbonation of galena and sphalerite and the sulphatization of galena, took place in the surface environment. And then primary silver was carried away off and was deposited on galena and/or copper sulfides during oxidation near the water table. Low partitionings of Fe in sphalerite assist that the minerals were formed at the relatively low temperature, which is coincided with previously reported homogenization temperature of fluid inclusions.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.421-433
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• 2023

The final disposal of spent nuclear fuel(SNF) from nuclear power plants takes place in a deep geological repository. The metal canister encasing the SNF is made of cast iron and copper, and is engineered to effectively isolate radioactive isotopes for a long period of time. The SNF is further shielded by a multi-barrier disposal system comprising both engineering and natural barriers. The deep disposal environment gradually changes to an anaerobic reducing environment. In this environment, sulfide is one of the most probable substances to induce corrosion of copper canister. Stress-corrosion cracking(SCC) triggered by sulfide can carry substantial implications for the integrity of the copper canister, potentially posing a significant threat to the long-term safety of the deep disposal repository. Sulfate can exist in various forms within the deep disposal environment or be introduced from the geosphere. Sulfate has the potential to be transformed into sulfide by sulfate-reducing bacteria(SRB), and this converted sulfide can contribute to the corrosion of the copper canister. Bentonite, which is considered as a potential material for buffering and backfilling, contains oxidized sulfate minerals such as gypsum(CaSO4). If there is sufficient space for microorganisms to thrive in the deep disposal environment and if electron donors such as organic carbon are adequately supplied, sulfate can be converted to sulfide through microbial activity. However, the majority of the sulfides generated in the deep disposal system or introduced from the geosphere will be intercepted by the buffer, with only a small amount reaching the metal canister. Pyrite, one of the potential sulfide minerals present in the deep disposal environment, can generate sulfates during the dissolution process, thereby contributing to the corrosion of the copper canister. However, the quantity of oxidation byproducts from pyrite is anticipated to be minimal due to its extremely low solubility. Moreover, the migration of these oxidized byproducts to the metal canister will be restricted by the low hydraulic conductivity of saturated bentonite. We have comprehensively analyzed and summarized key research cases related to the presence of sulfates, reduction processes, and the formation and behavior characteristics of sulfides and pyrite in the deep disposal environment. Our objective was to gain an understanding of the impact of sulfates and sulfides on the long-term safety of high-level radioactive waste disposal repository.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.243-250
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• 2010

Froth flotation of complex copper ore from Indonesia Jambi mine has been carried out to produce high-grade Cu concentrate. Since the ore contained minor Cu sulfides in addition to major Cu carbonate (malachite), copper concentrate was recovered by two-stage process of flotation, which consisted of copper sulfide flotation using xanthate followed by copper oxide flotation using oleic acid. The copper sulfide concentrate of 57.5% Cu grade with 9.5% recovery was obtained by copper sulfide flotation under conditions of 300 g/t collector (1 : 1 mixture of xanthate series Aero Promoter 211 and Aero Promoter 242) and pH 6.0 pulp. In subsequent copper oxide flotation on sink products, the concentrate of 30.8% Cu grade with 92.1% recovery was obtained under the conditions of oleic acid 300 g/t, AF65 50 g/t, pH 8.0 and 2 times cleaning. The flotation techniques which can achieve a Cu grade of 36.1% and a recovery of 92.1% have been developed from the two-stage process of flotation.

• Economic and Environmental Geology
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• v.42 no.1
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• pp.1-8
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• 2009

The Haman mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Almost all occurrences in the Haman area are representative of copper-bearing polymetallic hydrothermal vein-type mineralization. Within the area are a number of fissure-filling hydrothermal veins which contain tourmaline, quartz and carbonates with Fe-oxide, base-metal sulfide and sulfosalt minerals. The Gunbuk, Jeilgunbuk and Haman mines are each located on such veins. The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage I, tourmaline + quartz + Fe-Cu ore mineralization; Stage II, quartz + sulfides + sulfosalts + carbonates; Stage III, barren calcite. Equilibrium thermodynamic data combined with mineral paragenesis indicate that copper minerals precipitated mainly within a temperature range of $350^{\circ}C$ to $250^{\circ}C$. During early mineralization at $350^{\circ}C$, significant amounts of copper ($10^3$ to $10^2\;ppm$) could be dissolved in weakly acid NaCl solutions. For late mineralization at $250^{\circ}C$, about $10^0$ to $10^{-1}\;ppm$ copper could be dissolved. Equilibrium thermodynamic interpretation indicates that the copper in the Haman-Gunbuk systems could have been transported as a chloride complex and the copper precipitation occurred as a result of cooling accompanied by changes in the geochemical environments ($fs_2$, $fo_2$, pH, etc.) resulting in decrease of solubility of copper chloride complexes.

• Korean Journal of Metals and Materials
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• v.49 no.3
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• pp.203-210
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• 2011

Bake hardening steels have to resist strain aging to prevent the yield strength increment and stretcher strain during press process and to enhance the bake hardenability during baking process after painting. The bake hardening steels need to control the solute carbon and the solute nitrogen to improve the bake hardenability. Ti and/or Nb alloying for nitride and carbide precipitation and low carbon content below 0.003% are used to solve strain aging and formability problem for automotive materials. However, in the present study, the effect of micro-precipitation of copper sulfide on the bake hardenability and fatigue properties of extremely low carbon steel has been investigated. The bake hardenability of Cu-alloyed bake hardening (Cu-BH) steel was slightly higher (5 MPa) than that of Nb-alloyed bake hardening (Nb-BH) steel, but the fatigue limit of Cu-BH steel was far higher (45 MPa) than that of Nb-BH steel. All samples showed the ductile fracture behavior and some samples revealed distinct fatigue stages, such as crack initiation, stable crack growth and unstable crack growth.

• Journal of Powder Materials
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• v.29 no.3
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• pp.252-261
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• 2022

Cobalt is a vital metal in the modern society because of its applications in lithium-ion batteries, super alloys, hard metals, and catalysts. Further, cobalt is a representative rare metal and is the 30th most abundant element in the Earth's crust. This study reviews the current status of cobalt extraction and recycling processes, along with the trends in its production amount and use. Although cobalt occurs in a wide range of minerals, such as oxides and sulfides of copper and nickel ores, the amounts of cobalt in the minerals are too low to be extracted economically. The Democratic Republic of Congo (DRC) leads cobalt mining, and accounts for 68.9 % of the global cobalt reserves (142,000 tons in 2020). Cobalt is mainly extracted from copper-cobalt and nickel-cobalt concentrates and is occasionally extracted directly from the ore itself by hydro-, pyro-, and electro-metallurgical processes. These smelting methods are essential for developing new recycling processes to extract cobalt from secondary resources. Cobalt is mainly recycled from lithium-ion batteries, spent catalysts, and cobalt alloys. The recycling methods for cobalt also depend on the type of secondary cobalt resource. Major recycling methods from secondary resources are applied in pyro- and hydrometallurgical processes.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.75-87
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• 2003

The Haman-Gunbuk mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Major ore minerals, magnetite, scheelite, molybdenite and chalcopyrite, together with base-metal sulfides and minor sulfosalts, occur in fissure-filling tourmaline, quartz and carbonates veins contained within Cretaceous sedimentary and volcanic rocks anu/or granodiorite (118{\pm}$3.0 Ma). The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage 1, tourmaline+quartz+Fe-Cu ore mineralization; Stage II, quartz+sulfides+sulfosalts+carbonates; Stage 111, barren calcite. Earliest fluids are recorded in stage I and early por-tions of stage II veins as hypersaline (35~70 equiv. wt.% NaCl+KCl) and vapor-rich inclusions which homogenize from ~30$0^{\circ}C$ to $\geq$50$0^{\circ}C$. The high-salinity fluids are complex chloride brines with significant concentrations of sodium, potassium, iron, copper, and sulfur, though sulfide minerals are not associated with the early mineral assemblage produced by this fluid. Later solutions circulated through newly formed fractures and reopened veins, and are recorded as lower-salinity(less than ~20 equiv. wt.% NaCl) fluid inclusions which homogenize primarily from ~200 to 40$0^{\circ}C$. The oxygen and hydrogen isotopic compositions of fluid in the Haman-Gunbuk hydrothermal system represents a progressive shift from magmatic-hydrothermal dominance during early mineralization stage toward meteoric-hydrothermal dominance during late mineralization stage. The earliest hydrothermal fiuids to circu-late within the granodiorite stock localiring the ore body at Haman-Gunbuk could have exsolved from the crystal-lizing magma and unmixed into hypersaline liquid and $H_2O$-NaCl vapor. As these magmatic fluids moved throughfractures, tourmaline and early Fe, W, Mo, Cu ore mineralization occurred without concomitant deposition of othersulfides and sulfosalts. Later solutions of dominantly meteoric origin progressively formed hypogene copper and base-metal sulfides, and sulfosalt mineralization.

• Journal of the Korean Chemical Society
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• v.11 no.1
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• pp.33-37
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• 1967

The influence of impurities contained in Marmatite ores on leaching of zinc was investigated. The zinc sulfide having the same crystal structure of natural Sphalerite was prepared by heating the zinc sulfide chemically precipitated, at $650^{\circ}C$ in nitrogen atmosphere. The activation energy of the sample was 25.8 kcal per mole in the leach test when oxygen partial pressure was 5 atm. and the value was exceedingly high compared to that obtained in Marmatite ores. Synthetic zinc sulfides added with small amount of each impurities were treated in same procedure. As a result, it was found that the leaching velocity was accelerated sharply when about 1 percent of $Cu^{++}$ was blended to the sample. Larger amount of iron has also same effect but the effect was minor compared to the copper. The other impurities indicated no appreciable catalytic action.

• Economic and Environmental Geology
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• v.31 no.3
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• pp.171-183
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• 1998

Early Tertiary volcanics, volcanoclastics and granodiorite occur in the Barton Peninsula, King George Island, Antarctica. In the granodioritic stock and volcanic rocks, propylitic alteration characterized by actinolite, epidote, chlorite and calcite is widespread, and disseminations and veinlets of sulfide minerals such as pyrite, chalcopyrite and bornite are ubiquitious. The study on the hydrothermal alteration near granodioritic stock can be summarized as follows; (1) granodiorite intrusion is a small, high level stock associated with calc-alkaline volcanism, and have high copper content, (2) high temperature type of propylitic alteration and common occurrence of copper sulfides in and around granodiorite intrusion, (3) low ${\delta}^{34}S$ values of pyrites by oxidational conditions of sulfide deposition, (4) low ${\delta}^{34}S$ values of quartz and feldspar in the granodiorite, and isotopic non-equilibrium by hydrothermal alteration. It suggest that hyrothermal alteration and mineralization near granodioritc stock should be genetically related to granodiorite intrusion in the Barton Peninsula.

• Resources Recycling
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• v.30 no.3
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• pp.18-29
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• 2021

Platinum group metals (PGMs) are used in a wide range of application fields such as catalysts, electronic devices, electrodes, electrical devices, fuel cells and high temperature materials due to their excellent electrical and thermal conductivity as well as chemical resistivity. Platinum group elements are generally associated with nickel-copper sulfides in magmatic rocks. Depending on the relative concentrations of the PGMs, they are produced either as the primary products or as by-products of the nickel and copper. However, PGMs natural resource deposits are strictly limited in countries such as South Africa and Russia. The annual supply of PGMs is only under 500 t. Considering the limited supply of PGMs, there will be a noticeable increase in the supply risk associated with PGMs in the near future. Therefore, it is extremely important to recover PGMs from secondary resources such as spent catalysts. This paper reviews on overview of PGMs extraction and recycling processes.