• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.357-366
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• 2007

Microorganisms participate in a variety of geochemical processes such as weathering and formation of minerals, leaching of precious metals from minerals, and cycling of organic matter The objective of this study was to investigate biogeochemical processes of iron leaching from magnetite ore by iron-reducing bacteria isolated from intertidal flat sediments, southwestern part of Korea. Microbial iron leaching experiments were performed using magnetite ore, Shinyemi magnetite ore, in well-defined media with and without bacteria at room temperature for a month. Water soluble Fe and Mn during the leaching experiments were determined by ICP analysis of bioleached samples, and the resulting precipitated solids were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The extent of iron leaching from magnetite in the aerobic conditions (Fe = 15 mg/L and Mn = 3.41 mg/L) was lower than that in the anaerobic environments (Fe = 32.8 mg/L and Mn = 5.23 mg/L). The medium pH typically decreased from 8.3 to 7.2 during a month incubation. The Eh of the initial medium decreased from +144.9 mV to -331.7 mV in aerobic environments and from -2.3 mV to -494.6 mV in anaerobic environments upon incubation with the metal reducing microorganisms. The decrease in pH is due to glucose fermentation producing organic acids and $CO_2$. The ability of bacteria to leach soluble iron from crystalline magnetite could have significant implications for biogeochemical processes in sediments where Fe(III) in magnetite represents the largest pool of electron acceptor as well as to use as a novel biotechnology for leaching precious and heavy metals from raw materials.

• Economic and Environmental Geology
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• v.8 no.1
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• pp.25-56
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• 1975

Most fluorite deposits of South Korea are distributed in three metallogenic zones namly as: Hwacheon, Hwangangni and Geumsan metallogenic zones. Fluorite deposits of each zone show The characteristic features owing to the geological setting, the structural patterns and their forming processes. deposits of the Hwacheon metallogenic zone are wholly fissure filling hydrothermal veins emThe bedded in shear fractures of the granite gneiss or schists of Precambrian age or in the cooling fractures of the granite and acidic hypabyssal rocks which are assumed to be a differentiated sister rock of the granite. Localization of most fluorite veins of the region is structurally controlled by NW and EW fracture systems and genetically related to the granite intrusion which ascertained as motivating rock of the fluorite mineralization. Fluorites are in most cases accompanied by quartz, chalcedony mainly and rarely agate, calcite, barite and sulphide base metals in some localities. The deposits of the Hwangangni metallogenic zone were formed at the last stage of hydrothermal polymineralization of W, Mo, Cu, Pb, Zn. The majority of the fluorite ore bodies were originated from replacement in limestone beds of Great Limestone Series or in calcareous interbeds of metasediments, whereas some cavity-filling ore bodies were embedded in phyllites and schists of the Ockcheon system and along the fissures in the replaced beds which were originated by volume decrease. The localization of fluorite deposits in this region is genetically related to the Moongyong granite which has been dated as middle Cretaceous, and controlled structurally by the $N20^{\circ}{\sim}50^{\circ}W$ extension fracture system or axial planes of folds, and by faults of NE direction that acted as paths of ore solution. The deposits of the Geumsan metallogenic zone are seemed to be formed through the similar process as that of Hwangangni metallogenic zone, but characteristic distinctions are in that they are more prevailing fracture filling veins and large number of the deposits are localized in roof-pendants or xenolithes of limestone in granites and porphyries. Igneous rocks that presumably motivated the mineraltzation are middle Cretaceous Geumsan granite and porphyries. Metallogenic epoch of the fluorite mineralization of South Korea are puesumably limited in early-middle Cretaceous. Studies of the fluid inclusions in fluorites of the region reveal that the homogenization temperature of the fluorite deposits are as follows: Hwacheon metallogenic zone : $95^{\circ}C{\sim}165^{\circ}C$; Hwangangni metallogenic zone : $97^{\circ}C{\sim}235^{\circ}C$; Geumsan metallogenic zone : $93^{\circ}C{\sim}236^{\circ}C$. Judging from the above results, the deposits of the Hwancheon region were formed at the epithermal stage, and those in the Hwangangni and Geumsan regions, were deposited at epithermal stage preceded by mesothermal mineralization of small scale in which some sulphide minerals were deposited. The analytical data of minor elements in the fluorites reveal that ore solutions of Hwangangni metallogenic zone seemed to be emanated in more acidic stage of magma differentiation than Hwacheon metallogenic zone did.

• Economic and Environmental Geology
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• v.29 no.5
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• pp.597-613
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• 1996

The tonnage of copper and tungsten produced at Dalseong mine by Taehan Tungsten Mining Company from 1961 to 1971 was 48,704 tons (M/T) of 4 wt.% Cu and 1,620 tons (S/T) of 70wt.% WO, but the mine was closed in 1974. Kyeongsan mine is a small abandoned cobalt mine with no data of production. To investigate the pollution level of the mine areas, soils, plants (Ohwi and Pampanini), stream waters and stream sediments were taken and Fe, Mn, Cu, Pb, Zn, Ni, Co, Cd and Cr were analysed by ICP. Soils are considerably contaminated by the heavy metals related to ore deposits, The heavy metal contents in plants vary with the species and parts of plants. Stream waters are anomalously high in heavy metals in the vicinity of the mines but the contents decrease downstream in the process of dilution and precipiation. However, heavy metal contents increase very high in stream sediments due to precipiation. To protect environmental damages caused by acid mine drainages wetlands must be constructed outside pits, and it is necessary to fill pits with waters, limestone chips and organic materials, which give reducing and alkaline condition to ores. Under the condition pyrite is protected from oxidation and aqueous iron sulphates precipitate to form stable secondary pyrite.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.2
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• pp.61-65
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• 1971

It is well known that shellfish absorb and accumulate heavy metals in the water environment. When the concentration of the heavy metals in the water is above guideline, we find abnormal accumulation of them in the body of shellfish. This study on green oysters is an instance showing the relationship between the abnormal accumulation of heavy metal and industrial wastewaters containing it. The influence of the industrial wastewaters upon shellfish has been discussed from the statistical, physiological, and saprobiensystematic points of view, and the author wants to make clear of the absorption and accumulation mechanism of the heavy metals and physiological situation. This paper deals with the copper-contents in the meat of oysters which were collected in Changhang Bay and Daechun area, the latter being not supposed to be influenced by the water of the Kum River during the period from October 1970 to february 1971. The mean value of the copper contents in oysters caught at the sampling station in the Changhang Bay area is ranged from 851.5 to 143.1mg Cu/kg wet base, and that of Daechun area varied from 13.0 to 27.4mg Cu/kg wet base, so an evident difference is seen at a significance of $0.1\%$. It appears that one of the environmental factors making copper concentrated in the oysters of the Changhang area is due to the copper-contaning slug being discharged into the sea water by the Changhang Ore Refinery.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.149-156
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• 1998

Enoronmental problems caused by certain geologic conditions Include pollution of soil by heavy metal, acidization of souls , acid mine drainage, Pound-water pollution, and natural radioactivity, as well as zoo-logical hazards such as landslide and subsidence. The acrid mine drainage contains large amount of heavy metals nO, therefore. cause serious pollution onto the nearby drainage systems and soils. In spite of this prospective environmental danger, few studies have been done on the acid mine drainage derived from non-metallic ore deposits such as pyrophyllitefNapseok) deposits. The sudo-bearing pyrophyllite ores, alteration zones, and mine talllngs of pyrophylllte deposits produce acrid mine drainage by the okidation of weathering. Compared to the fresh host rocks, the ores and altered rocks of pyrophyllite deposits produce acidic solution which contain higher amount of heavy metals because of OeP lower buffering capacity to acrid solution. The pus of urine water and nearby stream water of pyrophyllite deposits are 2.1~3.7, which are strong- ly acidic and much lower than that (6.2~7.2) of upstream water and than that (6.8~7.6) of the stream water derived from the non-mineralized area. This study reveals that this acrid mine drainage can affect the downstream area which is 8km far from the pyrophyllite deposits, even though the drain Is diluted with abundant non-contaminated river water This suggmists that not only acid mine drainage but also the sulfide-bearing sediments originated from the pyrophyllite deposits move downstream and form acidic water through continuous oxidation reaction. The heavy metals such as Pb, Zn, Cu, Cd, Nl, Mn and Fe are enriched In the mine water of low pH, and their contents decrease as the pH of mine water Increases because of the Influx of fresh stream wainer. SoUs of the Pyrophyulte deposits are characterized by high contents of heavy metals. The stream sediments containing the yellowish brown precipitates formed by neutralization of acid mine drainage occur in all parts of the stream derived from the pyrophyllite deposits, and the sediments also contain high amounts of heavy metals. In summary, the acid mine drainage of the pyrophyllite deposits is located in the upstream part of Hoidong water reservoir in Pusan contains large amounts of heavy metals and flows into the Holdong water reservoir without any purification process. To protect the water of Holdong reservoir, the acid mine drainage should be treated with a proper purification process.

• Resources Recycling
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• v.7 no.5
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• pp.3-12
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• 1998

The most recent research in precious metal processing is found in the increasing use of heap leaching for the extraction of gold from low grade ores and tailing dumps because heap leaching has several advantages compared to traditional milling. They include simplicity, lower capital and operating costs, faster starter-up time and environmental safety. In this paper, an attempt has been made to provide an overview of important factors involved in the implementation of heap leaching technology as a vehicle for gold extraction from its low grade ores. Brief discussions of the various important elements to this process has been made to ascertain the heap leaching characteristics, such as heap leaching chemistry, natural factors, ore preparation, heap and pad construction, solution collection system, pond system, metal extraction, and economical consideration.

• Journal of Powder Materials
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• v.28 no.2
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• pp.164-172
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• 2021

Titanium is the ninth most abundant element in the Earth's crust and is the fourth most abundant structural metal after aluminum, iron, and magnesium. It exhibits a higher specific strength than steel along with an excellent corrosion resistance, highlighting the promising potential of titanium as a structural metal. However, titanium is difficult to extract from its ore and is classified as a rare metal, despite its abundance. Therefore, the production of titanium is exceedingly low compared to that of common metals. Titanium is conventionally produced as a sponge by the Kroll process. For powder metallurgy (PM), hydrogenation-dehydrogenation (HDH) of the titanium sponge or gas atomization of the titanium bulk is required. Therefore, numerous studies have been conducted on smelting, which replaces the Kroll process and produces powder that can be used directly for PM. In this review, the Kroll process and new smelting technologies of titanium for PM, such as metallothermic, electrolytic, and hydrogen reduction of TiCl₄ and TiO₂ are discussed.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.183-189
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• 2010

It is of importance to separate Ni(II) and Co(II) from Mg(II) in solution which was leached from nickel laterite ore. In order to investigate the possibility of separating Ni(II) and Co(II) from Mg(II), adsorption behavior of the three metals from individual and mixed sulfate solutions was investigated by using Diphonix resin. The concentration of each metal in solution was fixed at 100 ppm and the pH of the sulfuric acid solution was changed from 5 to 7. At ambient temperature, the adsorption behavior of the three metal ions followed Langmuir adsorption isotherm. The loading capacity of Diphonix resin for the three metal ions was obtained from the Langmuir isotherm. Since adsorption behavior of the three metal ions from the mixed solution was similar to each other, it was found to be difficult to separate Ni(II) and Co(II) from Mg(II) by using Diphonix resin.

• Resources Recycling
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• v.20 no.2
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• pp.30-44
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• 2011

This review describes the involvement of different microorganisms for the recovery of uranium from the ore. Mainly Acidithiobacillus forrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans are found to be the most widely used bacteria in the bioleaching process of uranium. The bioleaching of uranium generally follows indirect mechanism in which bacteria provide the ferric iron required to oxidize $U^{4+}$. Commercial applications of bioleaching have been incorporated for extracting valuable metals, due to its favorable process economics and reduced environmental problems compared to conventional metal recovery processes such as smelting. At present the uranium is recovered through main bioleaching techniques employed by heap, dump and in situ leaching. Process development has included recognition of the importance of aeration of bioheaps, and improvements in stirred tank reactor design and operation. Concurrently, knowledge of the key microorganisms involved in these processes has advanced, aided by advances in molecular biology to characterize microbial populations.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.21-34
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• 1989

Chindong granites are classified into granodiorite, tonalite and quartz-diorite, and Yucheon - Eonyang granites into monzo-granite by the Streckeisen diagram. These granitic rocks of Cretaceous age show trend of calc-alkaline magma, and the magmatic evolution from basic to acidic rocks is consistant with the general crystallization path of the Cretaceous granitic rocks in the Gyeongsang basin. On the basis of petrological and petrochemical data, variation of major elements (K, Na, Ca, Mg) and trace elements (Rb, Sr, Ba) including ore metals (Cu, Pb, Zn) in the Cretaceous granitic rocks were studied in detail in order to investigate geochemical difference of the granitic rocks in relation to mineralization between Cu province and Pb-Zn province in the Gyeongsang basin. There is clear difference in content of the major elements between Chindong granites and Yucheon-Eonyang granites : Chindong granites have low content of K (1.62%) and Na (2.53%), and high content of Ca (3.75%) and Mg (1.42%) whereas Yucheon-Eonyang granites have high content of K (3.56-3.60%), and low content of Ca (0.96-0.26%) and Mg (0.26-0.21%). There is also clear difference in content of trace lithophile elements between Chindong granites and Yucheon-Eonyang, granites : Chindong granites have low content of Rb (86ppm) and Ba (330ppm), and high content of Sr (405ppm) while Yucheon-Eonyang, granites have high content of Rb (144-161ppm) and Ba (983-1030ppm), and low content of Sr (157-136ppm). The lithophile trace elements of Rb and Sr vary with close relationship to major elements of K and Ca, respectively. Therefore, Chindong granites are much easily distinguished from Yucheon-Eonyang granites by using relationship of K with Rb and Ca with Sr : K<3%, Rb<100ppm, Ca<2% and Sr>200ppm for Chindong granites, and K>3%, Rb>100ppm, Ca<2%, and Sr<200ppm for Yucheon-Eonyang granites. There is not clear difference in content of trace ore metals between Chindong granites and Yucheon-Eonyang granites : Chindong granites of the Cu province have low Cu content (15ppm) which is nearly equal to 13-14ppm of Yucheon-Eonyang granites of the Pb-Zn province, and Yucheon-Eonyang granites have Pb content (29-27ppm) which is rather lower than 37ppm of Chindong granites. But Cu is anomalously high in the mineralized part of Chindong granites in Gunbuk-Haman area, and Zn is apparently higher in Yucheon-Eonyang granites (51-37ppm) than in Chindong granites (29ppm). K/Pb ratio is also c1early distinguishable between Chindong granites (<850) and Yucheon-Eonyang granites (>850). Thus, it may be possible to apply geochemical difference of the granites to distinguish whether a Cretaceous granitic body is Cu related rock or Pb-Zn related rock, and whether it belongs to Cu province or Pb-Zn province in the Gyeongsang basin.