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An integrated hydrometallurgical process was used for the zinc leaching and purification from a zinc ore containing 9.75 wt% zinc. The zinc minerals in the ore were hemimorphite, willemite, and calcophanite. Main gangue minerals were quartz, goethite, hematite, and calcite. Central composite design (CCD) method was used to design leaching experiments and the optimum conditions were found as follows: 30% of solid fraction, 22.05% sulphuric acid concentration, and the leaching temperature of 45 °C. The PLS containing 35.07 g/L zinc, 3.16 g/L iron, and 4.58 g/L manganese impurities was produced. A special purification process including Fe precipitation and Zn solvent extraction was implemented. The results showed that after precipitation of iron, Zn extraction of 88.5% was obtained with the 2 stages extraction system composed of 30 vol% D2EHPA as extractant. The overall Zn recovery from the ore was 71.44%. Therefore, an appropriate solution containing 16.6 g/L Zn, 0.05 g/L Fe, and 0.11 g/L Mn was prepared for the electro-winning unit without using the roasting and calcination steps (conventional method), which result in environmental pollution.

The advent and development of new technologies that will provide better yields, cleaner and a safer environment is a global challenge for the researchers. Traditional solvents used in extraction of minerals are at many times hazardous thereby constituting threats to the ecology. The work reports the direct bioleaching of zinc sourced from Abakaliki-Ishiagwu complex zinc sulphide ore deposit. The sphalerite ore is predominant in Zn with other associated metals Pb, Cu, Fe, Ni, Sb, As, Cd, Au, V, Co, Ag, K, Al and Ca. It covers the pre extraction processes of mineral comminution (crushing and grinding); separation by froth flotation; and roasting. Agro-cyanide was extracted from cassava plant (Manihot esculenta Crantz) leaves and was used as leachant without any additive. The result of atomic absorption spectrometry (AAS) analysis of the leached liquor (pregnant solution) shows that lead, copper and iron in addition to Zinc, were obtained from the leached ore roast at 149.25 ppm (Zn), 79.25 ppm (Pb), 0.25 ppm (Cu) and 4.25 ppm (Fe) extraction after 21 days. Elongated contact of ZnO ore is not encouraging for Zn extraction as there is a decline in the quantity of Zn, Fe and Cu as the leaching time (days) increases. The mechanism of the Leach next faction is yet to be fully ascertained, hence the need for further work in the area.

The hexagonal plate lead iodide (PbI2), with band gap energy of 2.31 eV, was firstly synthesized from mixed sulfide-oxide lead and zinc ore by an in-situ reduction-selective leaching-precipitation ...

The present study deals with a microwave-assisted oxidation roasting oxide–sulphide zinc ore technology of with addition of manganese dioxide. Effects of roasting parameters such as MnO2 addition level, roasting temperature, and holding time are studied by using the Central Composite Design (CCD). Meanwhile, zinc calcines are characterized by phase compositions analyses(XRD), structure characteristics of minerals (FT-IR), micro-area chemical analyses (SEM-EDAX) and elemental valence bonding analyses (XPS), which prove to be in accordance with the CCD results. The optimum roasting conditions are decided as MnO2 addition level being 85.14 %, roasting temperature 680 °C, and holding time 41 mins, and oxidation degree of zinc can reach 88.22 %. Besides, when MnO2 addition level reaches a certain value, zinc will aggregate in a form of ZnMn2O4, one battery material.

The reuse of minerals from tailings is essential to generate less impact on the environment. The investigation of methods that aim to recover elements that can generate by-products from mining tailing has been studied, such as, for example, the zinc beneficiation tailing. The tailing acquired in the flotation step of the zinc beneficiation was initially characterized to investigate alternatives routes to obtain by-products from the gangues found in this tailing. The gangue of zinc tailing may contain dolomite, hematite, and impurities that are considered toxic elements, e.g. lead and cadmium. This work aimed to obtain MgSO4 and CaSO4 from real flotation tailing generated in zinc beneficiation. Thus, using physical processing, thermodynamic simulation (FactSage software), and hydrometallurgical route from dolomite. The following composition was identified in the characterization of zinc tailing by inductively coupled plasma optical emission spectrometry (ICP-OES): 7.96% Fe, 10.3% Mg, 17.4% Ca, 1.47% Si, 1.74% Zn, 0.2% Pb, 0.33% Al, 0.02% Cd, and 0.07% Mn. X-ray diffractometry (XRD) identified the phases of dolomite, hematite, and quartz. In the SEM-EDS analyses, it was possible to observe the disintegrated hematite, dolomite, and quartz particles, which allow the physical processing of these phases. Therefore, a dolomite concentration was investigated in the magnetic and gravity separation to eliminate mainly iron from the material understudy. The magnetic separation with the rougher cleaner route showed a better concentration of dolomite (90.3%) found in the non-magnetic fraction. The non-magnetic fraction was characterized by ICP-OES and presented a composition of 0.34% Al; 21.6% Ca; 0.04% Cd; 2.7% Fe; 11.9% Mg; 0.08% Mn; 0.2% Pb; 1.37% Si; and 1.73% Zn. Subsequently, a simulation was performed with the FactSage software to evaluate the leaching conditions varying the S:L ratio, the sulfuric acid concentration, and temperature were studied. Initially, pure dolomite was used in the simulation as a reference. Afterward, the composition was provided in the non-magnetic fraction of 90.3% and the other phases found in the zinc tailing were considered. The conditions for the pure dolomite were selected in 1.2mol.L-1 in a S:L ratio equal to 1:10, at room temperature showed 100% Mg extraction. Then, the simulation with 90.3% dolomite had 100% Mg extraction in 1.0mol.L-1 H2SO4 in a S:L ratio equal to 1:10 at room temperature. The leaching tests were performed using these conditions, varying the temperature in 25 - 50 - 75 and 90°C and the time from 5 to 180min, which a Mg and Ca extraction yield of 72% ± 5% and 2%, respectively, were obtained at 50°C in 35min. Using the cementation step, the purification method resulted in a 92.3% cadmium removal in the liquor from leaching with zinc powder in a 100:1 ratio in 5min at 25°C. The by-products obtained were MgSO4 and CaSO4, to be used in agriculture, magnesium sulfate (40% of MgSO4·7H2O for each 1kg) as a fertilizer (secondary macronutrient), and calcium sulfate as a soil conditioner (7.5% for each 1kg). O reaproveitamento de minerais a partir de rejeitos é fundamental para gerar menos impactos ao meio ambiente. A investigação de métodos que visam recuperar elementos que possam gerar subprodutos a partir de rejeitos de mineração vêm sendo estudada, como por exemplo, o rejeito do beneficiamento do zinco. O rejeito da etapa de flotação do beneficiamento do zinco foi caracterizado, inicialmente, para investigar novas rotas para obtenção de subprodutos a partir de gangas. A ganga do rejeito do zinco contém dolomita, hematita e impurezas, que são consideradas elementos tóxicos, ex.: chumbo e cádmio. O trabalho teve como objetivo a obtenção de sulfato de magnésio e sulfato de cálcio a partir do rejeito utilizando processamento físico, simulação termodinâmica (software FactSage) e rota hidrometalúrgica a partir da dolomita. Identificou-se na caracterização do rejeito de zinco, por espectrometria de emissão óptica por plasma acoplado indutivamente (ICP-OES) a seguinte composição: 7,96% Fe, 10,3% Mg, 17,4% Ca, 1,47% Si, 1,74% Zn, 0,2% Pb, 0,33% Al, 0,02% Cd, e 0,07% Mn. A difratometria de raios-X (DRX) identificou as fases de dolomita, hematita e quartzo. Nas análises realizadas no MEV-EDS foi possível visualizar as partículas desagregadas de hematita, dolomita e quartzo o que permitiu uma separação física dessas fases. Portanto, a concentração de dolomita foi investigada na separação magnética e gravítica para eliminar principalmente o ferro do material em estudo. A separação magnética rougher cleaner apresentou uma melhor concentração da dolomita encontrada na fração nãomagnética a qual foi caracterizada por ICP-OES e apresentou uma composição de 0,34% Al; 21,6% Ca; 0,04% Cd; 2,7% Fe; 11,9% Mg; 0,08% Mn; 0,2% Pb; 1,37% Si; e 1,73% Zn. Posteriormente, realizou-se uma simulação com o software FactSage para avaliar as melhores condições de lixiviação referente a relação S:L, variação da concentração de ácido sulfúrico e da temperatura. Inicialmente, utilizou-se na simulação, como referência, a dolomita pura e, em seguida, considerou-se a composição obtida na fração não-magnética (90,3%) e os demais elementos encontrados. As condições da dolomita pura foram selecionadas em 1,2mol.L-1, em uma relação S:L igual a 1:10, e temperatura a 25°C, obtendo-se uma extração de 100% do Mg na simulação. Em seguida, a simulação com 90,3% de dolomita obteve uma extração do Mg de 100% utilizando 1,0mol.L-1 de H2SO4 na relação S:L igual 1:10 a 25°C. Os ensaios de lixiviação foram realizados utilizando essas condições, variando-se a temperatura em 25 - 50 - 75 e 90°C e o tempo de 5 a 180min. Obteve-se um rendimento da extração de Mg de 72%± 5% a 50°C em 35min. Na etapa de purificação, utilizando o método de cementação, houve uma remoção do cádmio de 90,2% no licor da lixiviação com o pó de zinco numa relação de 100:1 em 5min a 25°C. Os subprodutos obtidos a partir da rota hidrometalúrgica foram MgSO4 e CaSO4, com o intuito de serem utilizados na agricultura, sendo o sulfato de magnésio (40% de MgSO4·7H2O para cada 1kg) como fertilizante (macronutriente secundário) e o sulfato de cálcio como condicionador do solo (7,5% para cada 1kg).

In this work, the dissolution properties of a dolomite containing zinc carbonate (smithsonite) oresample having 24.22% ZnO were determined in sodium hydroxide solutions using X-ray diffraction(XRD), Fourier-transform infrared spectroscopy (FT-IR), thermal (TG/DTA) and chemical analysesmethods. It was observed that the dissolution efficiency value of zinc continuously increased withthe increase of sodium hydroxide concentration from 1 to 4 M and the highest zinc dissolutionefficiency of 70.7% was reached after dissolution in 4 M NaOH solution at temperature of 298 K.The XRD, FT-IR, TG/DTA and chemical analyses of undissolved solids obtained after dissolutionof ore sample in 4 M NaOH solution at 298 K revealed that the smithsonite phase in the samplecompletely dissolved whereas the main gangue mineral dolomite remained practically unaffected,showing the selectivity of sodium hydroxide solution considering zinc dissolution. Although thesmithsonite phase in the sample totally dissolved, hundred percent zinc dissolution efficiencycould not be reached, which may indicate the presence of zinc in the gangue components, i.e.dolomite, clay minerals etc., of the studied ore sample., Bu çalışmada, dolomit içeren bir çinko karbonat (simitsonit) cevher numunesinin (%24,22 ZnO)sodyum hidroksit çözeltilerindeki çözünme özellikleri X-ışını kırınımı (XRD), Fourier dönüşümlükızılötesi spektroskopisi (FT-IR), ısıl (TG/DTA) ve kimyasal analiz yöntemleri kullanılarakbelirlenmiştir. Sodyum hidroksit derişiminin 1’den 4 M’ye artırılmasıyla çinko çözünme verimideğerinin sürekli olarak arttığı gözlenmiş ve %70,7’lik en yüksek çinko çözünme verimine 298K sıcaklıktaki 4 M NaOH çözeltisinde yapılan çözme işlemi sonrasında ulaşılmıştır. Cevhernumunesinin 298 K’deki 4 M NaOH çözeltisinde çözündürülmesi sonrasında elde edilençözünmemiş katıların XRD, FT-IR, TG/DTA ve kimyasal analizleri, numune içindeki simitsonitfazının tamamen çözündüğü halde ana gang minerali dolomitin büyük ölçüde çözünmeden kaldığınıortaya çıkarmakta, bu durum da çinko çözünmesi dikkate alındığında sodyum hidroksit çözeltisininseçiciliğini göstermektedir. Numunedeki simitsonit fazının tümünün çözünmesine rağmen yüzdeyüz çinko çözünme verimine ulaşılamaması, çalışılan cevher numunesi içinde bulunan dolomit, kilmineralleri vb. gibi gang bileşenlerindeki muhtemel çinko varlığını işaret etmektedir.

In Viet Nam, non-sulfide zinc ore in the Cho Dien deposit has been exploited for a long time. Up to the present, zinc ore remains the major exploited ore in Cho Dien. There are numerous studies of Pb-Zn ore in Cho Dien. However, most of the studies have dedicated only to description of mineralogical and chemical composition of Pb-Zn ore. There has been no publication on this non-sulfide zinc ore. Based on the mineralogical studies, the content of Pb and Zn in groundwater determined by reflective microscope, SEM, EPMA and ICP-MS methods, the study explained the formation of secondary non-sulfide zinc ore in the Cho Dien deposit. Strong weathering process makes the upper part of ore bodies completely oxidized. Difference in geochemical behavior of lead (Pb) and zinc (Zn) in the oxidation process of Pb-Zn ore is the reason to form non-sulfide zinc ore in the Cho Dien deposit. Oxidation of primary Pb-Zn ore is mainly sphalerite, pyrite, galena minerals which creates a low pH environment and transforms of zinc from immobile (sphalerite - ZnS) to mobile (Zn2+) and retained in solution under acid pH conditions whereas lead has the tendency to form soluble minerals (anglesite, cerussite). The acid neutralization actions of the surrounding rocks make zinc precipitate, to form secondary non-sulfide zinc minerals.ReferencesAndreas Nuspl, 2009. Genesis of nonsulfide zinc deposits and their future utilization (www.geo.tu-frei berg.de/oberseminar/OS_09/Andreas_Nuspl.pdf.Boland M.B., et al., 2003. The Shaimerden supergene zinc deposit, Kazakhstan: Economic Geology, 98(4), 787-795.Chau N.D., Jadwiga P., Adam P., D.V. Hao, L.K. Phon, J. Paweł, 2017. General characteristics of rare earth and radioactive elements in Dong Pao deposit, Lai Chau, Vietnam, Vietnam J. Earth Sci., 39(1), 14-26.Dao Thai Bac, 2012. 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Society for geology applied to mineral deposits (SGA) News, Number 15. https://www.e-sga.org/fileadmin/sga/newsletter/news15/art01.html.McPhail D.C., et al., 2003, The geochemistry and mobility of zinc in the regolith: in Roach, I.C., ed., Advances in Regolith, 287-291.Murray W. Hitzman, et al., 2003. Classification, genesis, and exploration guides for non-sulfide zinc deposits: Economic Geology, 98(4), 685-714.Nguyen V.P., 2013. Wet tropical wethering in Viet Nam. Natural Science and Technology Publisher.Nicola Mondillo, 2013. Supergene Nonsulfide Zinc-Lead Deposits: The Examples of Jabali (Yemen) and Yanque (Peru). Doctoral thesis.Nordstrom D.K., Alpers C.N., 1999. Geochemistry of acid mine waste. Review in Economic Geology, the environmental geochemistry of ore deposits/Eds. G.S.Plumlee, M.J. Logsdon. Part A: Processes, techniques, and health issues, 6A, 133-160.Reynolds N.A., et al., 2003. The Padaeng Supergene Nonsulfide Zinc Deposit, Mae Sod, Thailand. Economic Geology, 98(4), 773-785.Sangameshwar S.R., Barnes H.L., 1983. Supergene Processes in Zinc-Lead-Silver Sulfide Ores in Carbonates: Economic Geology, 78, 1379-1397.Stumm W., Morgan J.J., 1996. Aquatic Chemistry, Third Edition. John Wiley & Sons, New York, NY.Takahashi T., 1960. Supergene alteration of zinc and lead deposits in limestone: Economic Geology, 55, 1083-1115.Thornber M.R. and Taylor G.F., 1992. The mechanisms of sulphide oxidation and gossan formation, in: Butt, C.R.M., and Zeegers H., (Eds.)., Regolith exploration geochemistry in tropical and subtropical terrains, in Govett G.J.S., ed., Handbook of exploration geochemistry: Amsterdam, Elsevier, 4, 119-138.Tran Trong Hoa, 2005. Potential assessment of By- products in lead-zinc and copper deposits of Northeast Vietnam. Final report.Tran Tuan Anh, 2010. 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The pre-treatment of zinc oxide bearing ores with high slime content is important to ensure that resources are utilized optimally. This paper reports an improved process using hydrocyclone de-sliming, dispersion reagents, and magnetic removal of iron minerals for the pre-treatment of zinc oxide ore with a high slime and iron content, and the benefits compared to traditional technologies are shown. In addition, this paper investigates the damage related to fine slime and iron during zinc oxide flotation, the necessity of using hydrocyclone de-sliming together with dispersion reagents to alleviate the influence of slime, and interactions among hydrocyclone de-sliming, reagent dispersion, and magnetic iron removal. Results show that under optimized operating conditions the entire beneficiation technology results in a flotation concentrate with a Zn grade of 34.66% and a recovery of 73.41%.

Photocatalysis is an advanced oxidation process that can degrade and mineralize organic pollutants in wastewater to carbon dioxide and water which was employed in this study. Tannery effluent was treated via batch photoreduction using Zinc oxide photocatalyst supported on y-Al2O3 and irradiated under visible light at the ambient condition of temperature. Zinc oxide obtained from Zinc ore and y-Al2O3 prepared from local kaolin were used to synthesize the ZnO/y-Al2O3. The synthesized photocatalyst was characterized by Brunnaer Emmett Teller (BET), X-ray Diffraction Spectroscopy (XRD), Scanning Electron Microscope (SEM), and X-ray Fluorescence (XRF). The result of the analysis reveals that the total surface area, total pore volume and mean pore size of the photocatalyst prepared were 65.452 m2g-1, 0.151 cm3g-1 and 9.892 nm respectively. The photocatalyst is crystalline and the SEM image shows the presence of pores. The ZnO/y-Al2O3 was used as a photocatalyst to reduce Chromium (VI) of a typical tannery wastewater. 96% reduction of 20 mg/L of Cr (VI) was achieved at 60 min, pH of 3, and a photocatalyst dosage of 2.5 g/L under visible light of 400 W intensity. The kinetic study revealed that the photoreduction was fitted into the pseudo-first-order Lagmuir-Hinshelwood kinetic model. This research demonstrated that ZnO/y-Al2O3 photocatalyst was effective in the photoreduction of the selected response for the treatment of tannery wastewater.

International audience; The numerous non-sulfide zinc ore deposits were the historical basis for the development of zinc mining in Iran. They include the Mehdiabad, Irankouh and Angouran world-class deposits, as well as the Zarigan and Haft-har deposits. These deposits were formed by supergene oxidation of primary sulfide minerals during the complex interplay of tectonic uplift, karst development, changes in the level of the water table, and weathering. Zn (Pb) carbonates, Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities along fractures related to uplift tectonics. Direct replacement of primary sulfides is accompanied by distal precipitation of zinc non-sulfide minerals in cavities or internal sediments filling. The mineralogy of the non-sulfide mineralization in all six deposits is generally complex and consists of smithsonite, hydrozincite, and hemimorphite as the main economic minerals, accompanied by iron and manganese oxy-hydroxides and residual clays. Commonly, non-sulfide minerals in these deposits consist of two types of ore: red zinc ore (RZO), rich in Zn, Fe, Pb-(As) and white zinc ore (WZO), typically with very high zinc grades but low concentrations of iron and lead. Typical minerals of the RZO are Fe-oxyhydroxides, goethite, hematite, hemimorphite, smithsonite and/or hydrozincite and cerussite. Common minerals of the WZO are smithsonite or hydrozincite and only minor amounts of Fe-oxyhydroxides and hemimorphite. Ó 2017, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

In our study, a detailed survey was conducted with the aim to determine the distribution and possible anthropogenic sources of molybdenum in river and stream sediments in the central Upper Silesian Industrial Region (Southern Poland), where for many years, iron and zinc smelters as well as coking and thermal power plants were operating. At the same time, this has also been a residential area with the highest population density in the country. Sediments (1397 samples in total) were collected from rivers and streams, and analysed for the content of molybdenum and 22 other elements. ICP-AES and CV-AAS methods were applied for the determination of the content of elements. The studies revealed molybdenum content in the range of < 0.5–204.8 mg·kg−1with the average content 1.9 mg·kg−1. About half of the samples contained < 0.5 mg·kg−1of molybdenum, and only 4.6% of the samples showed values > 5 mg·kg−1. The spatial distribution of molybdenum demonstrated by the geochemical map has indicated that the principal factor determining its content in sediments is the discharge of wastewater from steelworks and their slag heaps. Another source of this element in sediments has been the waste of the historical mining of zinc ore and metallurgy of this metal. Additionally, molybdenum migration from landfills of power plants, coal combustion and Mo emission to the atmosphere and dust fall-out have been significant inputs of Mo pollution to the sediments.

Life cycle assessment was carried out via ReCiPe H method to evaluate environmental impact of the hydrometallurgical zinc production chain in China. National statistical data and process-based life cycle inventory (LCI) were used to build a zinc production LCI at the macro level. To confirm the credibility of this study, an uncertainty analysis was conducted via Monte-Carlo simulation. The impacts of climate change, human toxicity, marine ecotoxicity, freshwater ecotoxicity, metal depletion, and fossil depletion categories on the overall environmental burden were examined. The overall environmental burden was dominated by key processes, such as zinc ore mining and energy (i.e., electricity and natural gas) consumption. In 2013, the amounts of carbon dioxide, sulfur dioxide, nitrogen oxide, particulate matter, zinc, and copper generated by hydrometallurgical zinc production were 2.60 × 10 7 , 4.29 × 10 4 , 6.77 × 10 4 , 1.23 × 10 4 , 1.38 × 10 3 , and 3.20 × 10 2 t. The first four substances accounted for 0.25%, 0.21%, 0.30%, and 0.10% of the overall national emission. Effective approaches to reduce the overall environmental impact of hydrometallurgical zinc production include improving the efficiencies of electricity, natural gas, and zinc ore consumption; substituting clean energy for coal-based electricity production; reducing the direct emission of zinc and copper; and increasing the national zinc recycle rate.

Pre-concentration consists of the preliminary discarding of a fraction of the mineral processing plant feed which contains little or none of the mineral of interest, reducing the mass to be processed in downstream operations (e.g. milling, concentration and dewatering), as well as the capital and operational costs. In this context, this study investigates the performance of density and sensor-based sorting separation methods in the removal of carbonate gangue of a zinc ore, in size fractions typical of crusher products, using sink and float tests with heavy liquids, jig stratification and laboratory scale ore sorting tests using an X-Ray Transmission (XRT) sensor. The best results were obtained through sink and float in heavy liquids, which indicated the possibility of discarding 30% of the feed mass, removing over 60% of the carbonates (CaO and MgO) and losing only 2% of the zinc. The ore sorting tests also presented positive results, with approximately 93% of metallurgical recovery in 70% of the mass for both size fractions tested. The jig stratification results were worse, since the zinc content discarded with this method was high. The results indicate significant reduction potential for Capex and Opex costs using pre-concentration strategy.

In this paper, a novel combination of phase transformation and leaching is proposed to recover zinc from an oxide–sulphide zinc ore. Accordingly, various analytical technologies, such as X-ray diffraction, chemical analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, are employed. The phase transformation of a raw ore and the effects of microwave heating and Na2O2 addition on zinc leaching are investigated. The results show that the addition of a strong oxide Na2O2 can directly transform the refractory phases, particularly zinc sulphide, into zinc sulphate. As a result, SO2 emissions are avoided and an environmentally friendly zinc recovery process is realised. Both microwave heating and the Na2O2 level have significant effects on phase transformation and zinc leaching. The zinc leaching rate can reach 82.06% under the following conditions of microwave heating: adding Na2O2 at a mass ratio of 25%, leaching in an ammonium chloride solution with a total ammonium concentration of 7.5 mol/L and an ammonia/ammonium chloride molar ratio of 1:1, adding NaClO as an aid-leaching reagent and leaching for 1 h. By contrast, the zinc leaching degree for the ore samples roasted in a traditional electric resistant furnace is only 30.62%. Moreover, at the same oxidation degree, the total energy consumption by the proposed process is 0.78 kWh/(kg·ore), which is lower than that by traditional heating (same power). Thus, the combination technology of microwave-heated phase transformation and leaching is effective in treating oxide–sulphide zinc ore.

Toya-Takarada mine is Au- and Ag-rich Kuroko-type deposit located in Takarada, Toya-mura, southwest Hokkaido, Japan. The deposits were hosted in rhyolitic tuff and mudstone of Middle Miocene age. Ore samples of fine-grained black ore, vuggy black-yellow ore, granular vuggy black ore, quartz-sulfide ore and massive quartz-barite ore were studied to identify the ore minerals association in the Toya-Takarada mine. The ore minerals are dominated by sphalerite, galena, chalcopyrite and pyrite with fewer amounts of electrum, tetrahedrite-tennantite, and other sulfosalt minerals with secondary mineral of covellite.The quantitative chemical analysis of ore minerals by EPMA indicated that FeS contents in sphalerite is low (0.3-1.2 mol.%) in all kinds of ore samples. Small grains of electrum as inclusions in pyrite are identified in vuggy black-yellow ore with Ag content around 32-33 atm %.In general, the silver minerals in Kuroko-type deposits occurred mainly in the black and yellow ores zone dominantly composed of sphalerite, galena, pyrite, chalcopyrite and barite as a form of electrum and/or argentian tetrahedrite-tennantite series. Thus, the massive quartz-barite ore sample of Toya-Takarada mine are also contain some rare silver sulfosalt minerals such as proustite, Cu-rich pearceite, geocronite-jordanite and fizelyite. Those minerals were found together in association with sphalerite. It seems that sphalerite was crystallized first followed by proustite and Cu-rich pearceite, then geocronite-jordanite and fizelyite are crystallized later.Sphalerites from quartz-sulfide ore of Toya-Takarada contain some fluid inclusions and measured homogenization temperatures are in the range of 164-247°C (av. 208°C) with salinity ranging from 1.9 to 4.7 wt.% NaClequiv. (av. 3.9 wt.% NaClequiv.). The mineral assemblage, iron content in sphalerite and silver content in electrum were indicated that sulfur fugacity was slightly higher during ore mineralization in Toya-Takarada mine.

The constantly increasing global demand of zinc metal along with the decreasing zinc ore reserves has led to an upward trend of zinc production from secondary sources. Galvanizing industry generates byproducts and wastes containing zinc in the form of intermetallic compounds or oxides (zinc dust). One such byproduct, waste pickling liquor (WPL) is generated in galvanizing industry during the pickling of defective galvanized material. WPL contains Zn and Fe in ionic form and is discarded after neutralization. In the present work, chemical precipitation method is used to recover zinc from WPL; with an objective to retain maximum possible iron within the WPL solution. The effect of precipitating agent concentration, number of reactions steps, temperature and stirring speed were considered to determine process parameters for maximum zinc recovery. The iron rich WPL solution with negligible quantities of zinc is a valuable ingredient for production of red oxide pigment. Thereby, two products are obtained by adopting this technique: (i) Zinc rich precipitates and (ii) iron rich pickling liquor. X-ray diffraction (XRD) analysis of precipitates (heated at elevated temperature), shows that zinc oxide and zinc ferrite phases were formed from the zinc rich precipitates.

Cementation is a prominent purification technique used for removal of copper, cadmium, cobalt, and nickel from impure zinc sulphate solution obtained after leaching of zinc ore. Zinc dust is primarily used for this purpose still the extent of purification is limited. The present study represents the encouraging result in context to utilization of zinc dust for better purification by altering its dosage, size and morphology. The investigations showed that 300% excess zinc dust dosage than stoichiometric results in enhanced cement formation. The study also revealed that fine size and ball milling of zinc dust favors cementation. Zinc dust of −300 mesh (BSS) after 2 h ball milling highly purifies the impure solution within 2 h contact time. The yield of the impurities removal after the optimized cementation is 100, 99.99, 100 and 15% for Cu, Cd, Ni and Co respectively. The kinetics of cementation has been also studied and revealed that the reaction is in mixed controlled mechanism for copper and cadmium cementation. At the same time, for nickel, it is considered to be chemically controlled. The activation energy for the cementation of copper, cadmium and nickel were 38.19, 30.87 and 68.15 kJ /mol, respectively. The estimated activation energies were found within the range which corroborates with the mixed and reaction model and ensures industrial feasibility of the proposed process.

This paper gives an overview of development the modern trends of geodetic measurements in the underground mine of lead and zinc ore 'Sasa' in Makedonska Kamenica. The precise geodetic measurements are of crucial importance, especially in the mines with underground exploitation. The precise geodetic data have a very big impact on safety in preparation the underground mine facilities, as well as in every working process in the mine exploitation.

The article describes the geological structure of the Amur stratiform zinc deposit, including ore-bearing flysch and overlying volcanic strata, the position of the sulfide ore body in geological section. Given the fact that a large part of the main ore body lies among carbonaceous deposits, in the latter by means of thermal analysis was estimated the degree of metamorphic change with the introduction of large Suunduk granite massif, as well as the study of content in them tungsten. Rare metal specialty of granite was previously proved by works of many researchers. We found that the ore-bearing carbonaceous shales contain industrial concentration of tungsten. In some cases they reach hurricane levels (up to 2200 g/t). However, analysis of the results of studies of black shale formation showed a high content of tungsten only in the eastern, closest to Suunduk massif, part of the geological allotment, but west of the boundary of the amphibolite and greenschist metamorphism facies, that we have identified according to thermal analysis. This allowed us to identify the promising area within which an attempt was made to estimate inferred resources of tungsten by category P 2 . The main parameters for calculation of resources are the average content of metal in carbonaceous deposits and the average thickness of the ore zones, which were calculated on the basis of data sturry and furrow samples. The result is a medium-scale object with resources of about 5 thousand tons of tungsten. It is known that zinc ore of Amur deposit currently classified as off balance ore, uneconomical to develop. However, given the estimated inferred resources of such an important associated metal such as tungsten in ore-bearing carbonaceous shales, the field may be attributed to the group of complex and ore to balance.

The Proterozoic Vazante zinc silicate district in Minas Gerais, Brazil, hosts world-class hypogene willemite deposits in dolomitic rocks interbedded with siliciclastic rocks deposited in subtidal to supratidal environments. Willemite ore bodies are structurally controlled along regional NE-trending structures which are interpreted as being active during the Neoproterozoic Brasiliano orogeny. The hydrothermal alteration is characterized by an early stage of Fe-dolomite, which replaced the host dolomitic rocks, followed by precipitation of minor sphalerite and then hematite and willemite. Elements commonly enriched in the zinc ore include As, Ba, Be, Bi, Cd, Co, Fe, Ge, In, Mo, Ni, Sb, Se, U, V and W. Mineralogical, fluid inclusion and isotopic data indicates that mixing of S-poor metalliferous saline fluids with meteoric water favored the formation of willemite ore. Carbonaceous phyllites from the underlying thick siliciclastic sequence show evidence of early enrichment in zinc (and ore-related metals) and remobilization, respectively, prior to and during the Brasiliano orogenic event. This unit is interpreted as a possible source of ore-related elements. It is proposed that during the Brasiliano orogeny, hot (T > 170 °C) saline fluids (>15 wt % eq. NaCl) leached metals from siliciclastic source rocks and precipitated willemite ore in the overlying dolomitic sequence along structures that favored mixing with oxidizing meteoric water.

The Proterozoic Aravalli-Delhi orogenic complex hosts a large number of economically important stratabound base metal sulphide deposits. In the present work, rock samples taken from Outcrop and Underground Mine of Sindeskar Kalan, Vedanta Group, Rajpura-Dariba-Bethumni Belt which are located at a distance of 76 Kms from Udaipur District (Rajasthan) have been studied. The chief litho units of the group are identified which contain sulfide-bearing calc-silicate and graphite mica schist, dolomite marble, calc-biotite schist and quartzite. Importance to the ore minerals like galena and sphalerite which have been reported in association with the buffer minerals like pyrite and pyrrhotite occurr in the host rocks of the study area. Ore petrography denotes two types of sphalerites, 1) highly deformed and dark brown colour, 2) less deformed and with light yellow colour. Galena shows high reflectance and a network of triangular pits. Pyrite shows high reflectance and anomalous anisotropism because of high brittleness.

In a VMS ore at Al Amar gold mine (level 640 FW-E), sulfide minerals are paragenetically ordered as follows: pyrite(I)–sphalerite–chalcopyrite–galena–pyrite(II), deformations vary from brittle to ductile deformation fabrics. Microscopically, the massive sulfides have pyrite porphyoblasts (up to ∼80%) that show evidence of creep dislocation as a result of low-temperature plastic deformation rather than brittle failure, whereas high-temperature annealment is completely lacking. Softer minerals such as chalcopyrite fill into fractures in pyrite as narrow slivers. Needle-shaped or lamellar morphology of chalcopyrite, together with the chemical composition of Fe-poor sphalerite (with maximum 0.99 wt% Fe) suggest a combined replacement–coprecipitation mechanism of chalcopyrite disease formation rather than an exsolution texture. Greenschist facies metamorphism produces an ore with distinct chalcopyrite disease into a stratified ore with microbands of chalcopyrite and sphalerite. Ore microfabrics and uncommon occurrence of epithermal stringers suggest noticeable effect of the Najd tectonics in the studied level. The EMPA analyses indicate that all sulfide minerals in the VMS ore are auriferous and the Au contents are considerable (up to 0.94, 1.31, 0.16 and 1.20 wt%; in sphalerite, chalcopyrite, galena and pyrite, respectively). Gold in pyrite is “invisible” whereas it occurs as submicroscopic inclusions in sphalerite, chalcopyrite and galena. The VMS ore of Al Amar deep horizons are characterized by the occurrence of “invisible gold”, Ag-free galena, Fe- and Ni-poor sphalerite, negligible hydrothermal alteration, plastic deformation of pyrite and non-exsolution origin of the chalcopyrite disease intergrowth which are together strong indicators of low-temperature (250–300 °C).

This study was conducted to build up the inventories of Pb isotopic compositions of major Pb pollution sources in South Korea. Since non-ferrous metal smelters are one of major anthropogenic sources, two smelters for zinc, each one of smelter for lead and copper were selected for the study. The Pb concentrations and isotopic compositions of metal ores, wastewater, sludge, metal rod and produced sulfuric acid were analysed to understand the Pb isotopic patterns in environment. The isotopic ratio, , of zinc ores from zinc smelter were in the range of 1.179~1.198 and the ratio of waste, flue gas and products samples were 1.105~1.147. This results implied that the isotopic patterns of output samples showed mixing patterns between two distinct metal ore soerces. In 2011, major importing countries of zinc ore were Australia, Peru and Mexico. Thus Pb isotopic patterns from zinc smelter is originated from the mixing patterns between less radiogenic Australian ores and more radiogenic South America`s ores. Lead smelters also showed the same mixing patterns with those of zinc smelters. However copper smelter showed same Pb isotopic patterns with more radiogenic South America`s ores.

The unusually high grade hypogene zinc ore at Angouran in northwestern Iran (40.4% Zn, 1.9% Pb in the sulfide ore, 28.1% Zn, 4.4% Pb in the carbonate ore, and 110 g/t Ag) formed from an initially highly saline, reduced, relatively acid hydrothermal brine at two successive sulfide and carbonate ore stages. The early ore stage consists of multiple phases of sphalerite dominated sulfide ore breccia with subordinate amounts of galena (± Pb sulfosalts), minor pyrite, and abundant barite. Sphalerite precipitated at moderate temperatures (≥ 155 °C) because of pH increase in the presence of hangingwall marble. Smithsonite precipitated at a higher pH value (≥ 7) and at lower temperatures (≤ 120 °C) from dilute solutions (salinities close to zero) by mixing of the Zn bearing brines with cool, HCO 3 − bearing waters. The first melting points of the primary (LV) fluid inclusions in sphalerite and in hydrothermal quartz are unusually low (≤ − 60 °C), close to the eutectic point of the ZnCl 2 –H 2 O system (− 62 °C). Total salinities taken from the ZnCl 2 –H 2 O system as a best approximation correspond to 26–41 eq mass % ZnCl 2 . The initial brine evolved to a CaCl 2 –NaCl rich solution with 27 eq mass % salinity. Gas densities (≤ 0.1 g cm − 3 for water vapor and ≤ 0.18 g cm − 3 for CO 2 ) in the fluid inclusions indicate low pressure (≤ 5 bar for water vapor, and ≤ 100 bar for CO 2 ) at the entrapment temperatures. At the first carbonate ore stage sulfides continued to precipitate characteristically as arsenopyrite with minor amounts of galena and pyrite. The abrupt change of the fluid composition at the sulfide–carbonate boundary was accompanied by a change of the fluid temperature and pressure that produced brecciation of the sulfide ore matrix and an almost total dissolution of barite and replacement by the hypogene smithsonite. Alteration is restricted to ore deposition and consists of weak sericitization and silicification with local dolomitization at the sulfide ore stage, and pervasive dissolution of the hangingwall marble, in particular at the carbonate ore stage. The breccia orebody at Angouran is sited at the crestal portion of a domed antiform at the lithological and thrust boundary of Neoproterozoic–Lower Cambrian footwall schists and the hangingwall marble in rapidly uplifted and exhumated Angouran Block east of the Geynardjeh Thrust Fault. The footwall schists occupy a detachment fault zone above imbricated nappe sheets of the basement metamorphic complex of the Sanandaj–Sirjan zone. During the Pliocene, the nappe sheets were thrust toward the southwest onto the Miocene felsic volcanic rocks of the Urumieh Dokhtar Volcanic Belt that are intruded by 10 Ma late Miocene basalts. The 11.9 Ma and 18.4 Ma zircon ages of the felsic volcanic rocks indicate the lower age limit of the ore body emplacement. The associations with large scale, mid-late Miocene, felsic volcanism along the active Tethyan belt, as well as the ubiquitous presence of the volcanic rock clasts in the sphalerite ore matrix, provide strong evidence of the involvement of hydrothermal processes at Angouran. Ore fluids were successively and pulsatorily generated within the seismically active region. A following geothermal activity appears to have had a significant input in the formation of the carbonate ore of the hypogene, as well as the supergene stage. Stable isotope data suggest complex interaction of element sources and processes. Allowing a broad interpretation, the sulfur isotopic composition of the sulfides δ 34 S (3.9 to 7.4‰) suggests that the sulfur could be sourced from evolving, mixed magmatic–basinal brine. The isotopic composition of the hypogene smithsonites (δ 13 C: 2.72 to 5.51‰, δ 18 O: 18.4 to 22.8‰) broadly supports the local geology and field relationships, which comply with a marble wallrock source for the carbonate ores. They lend support to the assumption that smithsonite was deposited from solutions with isotopic composition similar to those involved in the hydrothermal dolomitization of the marbles. The excess of dissolved marble precipitated as large volumes of travertine and as late calcite veins (δ 13 C: 18.8 to 20.3‰, δ 18 O: 3.1 to 6.4‰) at the mineralization site. Isotope values of the travertine (δ 13 C: 4.5 to 6.6‰, δ 18 O: 20.1 to 21.1‰ V-SMOW) are consistent with the involvement of CO 2 derived from thermogenic decarbonization of the host marble by waters of dominantly meteoric origin, most likely concomitantly with ore forming processes. The Angouran deposit is the only reported case of a two stage, hypogene zinc sulfide–zinc carbonate mineralization, and represents a new style of nonsulfide zinc mineralization.

The application of comminution technology such as the high-pressure grinding rolls (HPGRs), which is able to generate a high density of cracks in the ore particles, is favourable for leaching processes. Extraction of metallic values by the heap leach process, can take place on the particles with partial exposure of mineral grains, if it can provide sufficient surface front for chemical attack by leaching solution. The aim of this study was to assess the benefits of high crack density in the ore particles produced using the HPGR and how it could diminish due to inadequate percolation of the leaching agent. A zinc ore was comminuted using HPGR at three different pressure settings and with a cone crusher for the control experiment. Subsamples from the (+23/−25, +14/−16, +5.25/−6.75 mm) size fractions were characterized and packed into leach reactors. The reactors were stopped from time to time to investigate the progress of crack and micro-crack growth and its effect on metal extraction using the X-ray computed tomography (CT). The results are validated with those obtained using traditional techniques such as SEM and QEMSCAN. Investigation of the leach reactors residue indicated significant changes in the particle size distribution (PSD) of initial feed toward the fine size fraction. The residues from the reactors leaching the material prepared using the HPGR product contained more fine particles than the reactors, which were fed by cone crusher product. These differences were up to 10.3%.

The processing mineralogy characteristics of an oxidized lead-zinc ore from Sichuan were studied systematically using numerous modern instruments. Results showed that lead and zinc oxide content in the ore exceeded the minimum industrial grade, and also included a relatively high concentration of silver and iron. This ore is composed of many different minerals. Major zinc-containing minerals include sphalerite, hemimorphite, smithsonite, hydrozincite, zinc-containing baileychlore, and zinc-containing dolomite and calcite. Lead-containing minerals are primarily galena and cerussite with small amounts of dechenite, cesaronite, anglesite, limonite and coronadite. Gangue minerals include dolomite and calcite. Dissemination size for the main minerals ranges from medium (0.04 mm) to fine (0.02 mm). All the valuable minerals are well liberated, including galena, sphalerite, cerussite, calamine, and smithsonite. However, the dissemination relationships are complex. Lead is concentrated mainly in galena and cerussite, while zinc occurs primarily in sphalerite, calamine, and smithsonite. The theoretical recovery for lead and zinc were estimated at 72% and 67%, respectively.

Streszczenie Występowanie złóż rud cynku i ołowiu w skałach dolomitowych sprawia, że otrzymane koncentraty sfa-lerytowe zawierają domieszkę dolomitu. Praktyka wskazuje, że znaczna część wprowadzanego magnezu z su­rowcami cynkowymi przechodzi do ostatniej fazy produkcji, elektrolizy cynku. Obecność magnezu w elektrolicie obniża przewodnictwo elektryczne elektrolitu i powoduje pogorszenie wskaźników techniczno-ekonomicznych. Celem opisanych w tym artykule badań było opracowanie metody usuwania magnezu z surowego koncentratu sfalerytowego na drodze chemiczno-flotacyjnej, stosując zużyty elektrolit pochodzący z elektrolizy cynku. Opracowanie ukierunkowano wokół doświadczalnego zobrazowania istniejących zależności i ustalenia opty­malnych warunków zaproponowanej procedury. Stopień wyługowania magnezu wynosił około 80%. Straty cynku wynosiły poniżej 2%, natomiast stężenie magnezu w roztworze wynosiło 20%. Z tych roztworów można odzys­kiwać magnez i cynk, co będzie przedstawione w następnej publikacji.

The hydrometallurgical zinc extraction from the willemite concentrate is impaired by the presence of high carbonate content. A stiff froth is produced causing zinc losses and acid consumption. A standard procedure was developed to deÞ ne the acceptable froth layer height in a laboratory test. Froth layers shorter than 2 cm resulted from carbonate content in the concentrate below 10.8%. The feasibility of adding a carbonate a otation stage to the circuit was tested in laboratory and pilot scales. Among the collectors investigated, only those presenting a saponiÞ cation degree above 189 mg KOH/mg were effective in the laboratory experiments. Oleine and rice bran oil soaps were selected for the pilot scale experiments. The Þ nal stage was a one month long industrial trial performed in a circuit consisting of three pneumatic cells G18. A comparison between the average results of the industrial trial including the carbonate a otation stage and data of the raw industrial concentrate indicated that the MgO content in the concentrate dropped from 3.7%–3%. Concurrently, the carbonate content in the concentrate dropped from 11%–10.6%, the zinc grade in the concentrate increased from 41.4%–42% and the zinc recovery increased from 86.6%–89.8%. The concentrate was processed in the hydrometallurgical plant with no frothing problems.

Uytenbogaardtite has been observed when examining the ores of the Konechnoe gold ore occurrence, West Taimyr, which is the first find for the entire Taimyr-Severnaya Zemlya region. It is associated with native gold (fineness 520–560‰), pyrite, and sphalerite. Sphalerite is characterized by Fe, Cd, Ag, and Cu impurities. Zinc is present in siderite. In the ores of the Konechnoe ore occurrence, there is also native gold of the early generation with sphalerite, the latter containing chalcopyrite lamellae and being in association with arsenopyrite, pyrite, and galena. The peculiar compositions of microinclusions and impurities in sphalerite and other minerals and the presence of accessory minerals, such as monazite and apatite, reflect the specific metallogenic and geochemical characteristics of the Minina-Bol’shevik structural-metallogenic zone and serve as indicators of the potential of the North Taimyr area in terms of gold, silver, zinc, copper, lead, cadmium, strontium, thorium, and lanthanides.

This paper aims to beneficiation of Um Gheig nonsulfide Zinc ore from its associated gangues using the gravity separation “shaking table” technique. The different operating parameters affecting of the efficiency of the separation process is evaluated. The zinc locality of Um Gheig represents one of the important nonsulfide zinc deposits along the coastal plain of the Red Sea Coast, Egypt. These zinc ores are called “calamines” and consist mainly of a mixture of zinc carbonates (smithsonite, hydrozincite) and zinc silicates (hemimorphite), with a variable content of calcite, goethite and Pb bearing minerals. Extensive mineralogical (using XRD, XRF) and petrographic studies have been carried out on the selected samples from Um Gheig Mine. Theses investigations show that, the nonsulfides mineral association in the deposit consists mainly of smithsonite (50.74%), hydrozincite (18.78%) and hemimorphite (14.78%) replacing both primary ore minerals and carbonate host rocks. Smithsonite occurs in two generations, cryptocrystalline mixed with goethite and rhombohedral crystals, precipitate in vugs and open space of the high grade ore. The main gangue minerals are calcite and goethite. XRF analysis indicates that the sample contains 47.50% ZnO, 1.55% PbO and about 29.28% L.O.I. Liberation and mineralogical investigation showed that higher degree of liberation (over 90%) between the valuable zinc bearing minerals and their gangues can be achieved below the size 0.106 mm. The results of gravity separation showed that the best operating parameters to obtain a concentrate with high assay and recovery are at inclination angle (4 degree), stroke length (2.5 cm), feed rate (150 gm / min), and water flow rate (25 l / min). At these optimum conditions a concentrate assaying 60.85 % ZnO was obtained with a recovery of ~90 %.

Pressure acid leaching of zinc silicate ores selectively separates valuable zinc from silica and iron, replacing conventional pyrometallurgical and hydrometallurgical methods. This study determines the optimum conditions for the dissolution of zinc silicate concentrates and achieves a higher zinc extraction (> 97%), lower iron (

Prior to the mastering of metallic zinc production in the mid-19th century, brass making in Europe was based on the so-called cementation process: within a more or less closed vessel, gaseous zinc is produced by the carbothermic reduction of zinc ore at around 1,000°C (±100°C), and simultaneously diffuses into metallic copper. Few ancient brass objects dated before the Industrial Revolution analyzed so far bear more than 30 wt.% zinc, so that this zinc content value has become a dating criterion for these artifacts. The systematic laboratory-scale experimental simulations of the ancient process presented here permit the multiple influences of temperature, isothermal treatment duration, and initial Zn/Cu ratio on the zinc content of the final products, and on the zinc recovery rates as well, to be investigated for the first time.

A new mathematical model was developed for leaching of zinc ores containing silicates such as hemimorphite which produce a gel during leaching with sulfuric acid. This model is based on the shrinking core model in which the particle size and the reacting core shrink simultaneously. It was shown that the actual dissolution time of the ore particles is longer than the time corresponding to the dissolution of chemical zinc oxide itself. It was suggested that because of the existence of silicates in the ore, a gelatinous layer was formed around the reacting core. Since the gel product is soft, it breaks apart when the particles collide and as a result, the particles shrink. However, a thin gelatinous layer always covers the reacting core which increases the mass transfer resistance and increases the leaching time. This model was applied to leaching of a zinc-rich tailing containing hemimorphite and the thickness of the gelatinous layer as well as the diffusion coefficient in this layer was determined.

Affecting factors, such as ore size, leaching temperature, holding time, alkaline concentration and liquid: solid ratio (volume/weight) (L/S), were studied to leach refractory hemimorphite [Zn4(Si2O7)(OH)·H2O] zinc oxide ores with NaOH solution in this paper. The impact of leaching recovery of Zn and its concomitant metals was checked through experiments. Results showed that when the ores of 65–76 µm size were leached for 2 h at 358 K in the presence of 5 mol/L sodium hydroxide and liquid:solid ratio of 10:1, the leaching rate of Zn, Al, Pb and Cd were about 73%, 45%, 11% and 5%, respectively, but that of Fe was less than 1‰. Moreover, the leaching experiments were repetitive and reliable. And the kinetic study indicates that the calculated activation energy is 45.7 kJ/mol, which illuminates that alkaline leaching the refractory hemimorphite [Zn4(Si2O7)(OH)⁎H2O] zinc oxide ores is controlled by the chemical process of the reaction of leach liquor and ores in the whole leach process.

The inhibition kinetics of iron oxidation was studied in a Leptospirillum ferriphilum -dominated, fluidized bed bioreactor culture, which was challenged with various concentrations of Fe 3+ , Zn 2+ and Ni 2+ . Iron(II) was oxidized in the presence of binary combinations of 40 g/L Fe 3 + + 10 g/L Ni 2+ , 30 g/L Fe 3 + + 40 g/L Zn 2+ , 60 g/L Zn 2+ + 10 g/L Ni 2+ and 60 g/L Ni 2+ + 10 g/L Zn 2+ . The data showed that L. ferriphilum was insensitive to the test metals, suggesting that the bacterium has application in ferric ion regeneration processes in circuits involving tank bioleaching of zinc and nickel sulfide concentrates. A combined method for determining the type and coefficients of inhibition was developed and validated with data from batch Fe 2+ oxidation experiments at pH 1.1 ± 0.2. Iron(III) competitively inhibited Fe 2+ oxidation, whereas Zn 2+ and Ni 2+ conformed to non-competitive inhibition model with inhibition coefficients ( K ii ) of 49.1 and 62.7 g/L, respectively. However, Mg 2+ and Na + had a compounding effect on Zn 2+ toxicity. The combined competitive and non-competitive inhibition model was applied for data on iron oxidation in the presence of Fe 3+ + Zn 2+ , Fe 3+ + Ni 2+ and Zn 2+ + Ni 2+ and good agreement was generally found between the model predictions and experimental data. The combined model can be used to predict the kinetics of bacterial iron oxidation in ferric ion regeneration for zinc and nickel concentrate tank leaching.

The proposed metallogenetic model presented in this paper is based on observations from the Iranian non-sulphide zinc deposits Mehdi-Abad, Iran-Kuh, and Kuh-e-Surmeh. The emplacement of non-sulphide ore can be generally subdivided into an ‘oxidation stage’ followed by a ‘post-oxidation stage’. The formation of carbonate-hosted non-sulphide zinc deposits is primarily controlled by three factors: climate, protore composition, and geology (lithology and structure) of the wall rocks. The climate controls the oxidation and metal transport, predominantly through the amount of meteoric water and the availability of oxygen, which indirectly is controlled through the thickness of the soil cover and biogenic oxygen consumption. Favourable conditions for oxidation are an arid climate with minimal biogenic activity within the soil. As a consequence, oxygen can reach the sulphides easily, resulting in higher metal concentrations of the supergene aqueous solutions. Dry climates are associated with a low water table, preventing descending Zn-bearing fluids from contact with the aquifer and thus from dilution, dispersion and removal of metals. Commonly, non-sulphide zinc deposits consist of two types of ore: red zinc ore, rich in Zn (> 20%), Fe (> 7%), Pb-(As) and white zinc ore, typically with very high zinc grades (up to 40%) but low concentrations of iron ( 4 2− ions during the oxidation stage leads to the precipitation of highly insoluble anglesite, which results in low Pb 2+ concentration within the fluid. Most of the zinc (up to 80% at pH 6 or 97% at pH 5) leaves the oxidation zone and precipitates as zinc carbonates in adjacent parts of the carbonate host rock. The neutralisation processes of the sulphuric acid with the carbonates of the host rock during the ‘oxidation stage’ lead to the formation of CO 2 (g). Consequently, the CO 2 partial pressure (P CO2(g) ) increases drastically and forms a “CO 2 (g)-halo” around the active oxidation zone. Thus, most of the zinc precipitates as smithsonite, which is stable and occurs exclusively in a high P CO2(g) environment. The P CO2(g) decreases during the ‘post-oxidation stage’ and reaches the level of atmospheric P CO2(g) . Under these conditions, hydrozincite becomes stable and starts to replace smithsonite. Most of the stage-I smithsonite becomes corroded and is altered to stage-II hydrozincite. The ‘post-oxidation stage’ is also associated with the successive formation of local zinc (hydro-) silicates, depending on the availability of SiO 2 within the solution. Generally, arid climates provide the best conditions for the preservation of non-sulphide deposits. The limited availability of meteoric water and deep to very deep water tables protect the non-sulphide ore from subsequent dissolution.

Jarosite is a leach residue that can be produced by industrial bulk metal treatment processes and typically has the chemical formula Mx Fe3 (SO4 )2 (OH)6 , where M normally represents a metal cation. The largest source of jarosite is electrolytic zinc processing [1], which worldwide has an annual production of 11-12 Mt and an associated jarosite waste of 5-6 Mt that can cause important challenges due to its classification as a problem waste. Moreover, as zinc ore typically contains many other commercial/critical metals, the content of valuable materials in this material is significant. An analysis of jarosite from Kokkola, Finland shows that it contained as much metal as many present day commercial ores: ~15% iron, 2% zinc, 3 % lead, 150 g/t silver, 0.5 g/t gold, 100 g/t indium and 40 g/t gallium. Until now, jarosite related research has concentrated on its use in landfill and construction purposes [2], though there is increasing interest in finding methods to efficiently reprocess/recycle jarosite into valuable products [3, 4]. The hydrometallurgical process currently under development by VTT and Aalto University exploits jarosite powdery nature to undertake wet chemical processing. This low cost and energy efficient operation is targeted at the recovery of concentrates which contain the major value-added metals.

In the Meža valley, lead – zinc ore has been exploited and processed for more than 300 years, which has strongly influenced the environment. Previous investigations have shown increased concentrations of lead and some other metals. At the end of the 20th century, the Meža River was considered a stream with the highest concentrations of heavy metals in Slovenia. When the mine and processing plants ceased to operate, the direct transfer of heavy metals into the environment has strongly decreased. However, the deposits of poor ore and wastes from ore processing have remained as an indirect source of heavy metal pollution. From those places heavy metals have been washed out into the nearby streams, and carried into the Meža River and further into the Drava River. Chemical analysis of the Meža River and its tributaries has shown heavy pollution of the upper Meža River sediments with lead, zinc, molybdenum and cadmium, and partly with arsenic. In the lower Meža valley, those concentrations are mildly decreased. Concentrations of cobalt, chrome, copper and nickel are increased in the area around Ravne as a result of the ironworks industry. Mu{enik and Jan~arjev potok, both tributaries of the Meža River, contribute a high portion of heavy metal load to the Meža River. A specific case is Helenski potok, in which the concentrations of heavy metals strongly surpass the concentrations measured at all other locations. Although more than 10 years have passed since the mine and ore processing plant in the upper Meža valley were closed, the production has ceased and the rehabilitation measures have been taken, the environment in the upper Meža valley is still highly polluted. doi:10.5474/geologija.2007.025 348 Julija Fux & Mateja Gosar

Low grade powdery zinc oxide ores (5.2% Zn, − 2 day − 1 , 8.09 × 10 − 3 day − 1 , 4.74 × 10 − 3 day − 1 respectively.

This work reports the effect of microwave irradiation on extraction of zinc from a bulk sphalerite (ZnS)/pyrrhotite (FeS) concentrate produced by flotation of tailings from the Rampura Agucha Lead–Zinc mines in India. This material could not be treated economically by conventional hydrometallurgy or pyrometallurgical methods due to low zinc concentration. Consequently, microwave assisted leaching was tested. Zinc leaching in sulphuric acid was rapid with > 90% dissolution after 6 min, further irradiation increased the zinc to 96% after 16 min. Iron dissolution increased up to 12 min irradiation and then decreased due to precipitation. Power consumption for > 90% Zn recovery was 0.36 kWh/kg concentrate. The leach solution contained 50–55 g/L zinc and 18–20 g/L iron which could be reduced to 0.54 g/L by jarosite precipitation. The ratio of Zn/Fe leached was 3.4 compared with the ratio of 0.6 for the concentrate showing significant selectivity for zinc over iron using this method.

DOI:10.17014/ijog.2.3.167-184Strong mineralized carbonate rock-bearing Pb-Zn-Cu-Ag-(Au) ores are well exposed on the Latong River area, Madina Regency, North Sumatra Province. The ore deposit is hosted within the carbonate rocks of the Permian to Carboniferous Tapanuli Group. It is mainly accumulated in hollows replacing limestone in the forms of lensoidal, colloform, veins, veinlets, cavity filling, breccia, and dissemination. The ores dominantly consist of galena (126 000 ppm Pb) and sphalerite (2347 ppm Zn). The other minerals are silver, azurite, covellite, pyrite, marcasite, and chalcopyrite. This deposit was formed by at least three phases of mineralization, i.e. pyrite and then galena replaced pyrite, sphalerite replaced galena, and pyrite. The last phase is the deposition of chalcopyrite that replaced sphalerite. The Latong sulfide ore deposits posses Pb isotope ratio of 206Pb/204Pb = 19.16 - 20.72, 207Pb/204Pb = 16.16 - 17.29, and 208Pb/204Pb = 42.92 - 40.78. The characteristic feature of the deposit indicates that it is formed by a sedimentary process rather than an igneous activity in origin. This leads to an interpretation that the Latong deposit belongs to the Sedimentary Hosted Massive Sulfide (SHMS) of Mississippi Valley-Type (MVT). The presence of SHMS in the island arc such as Sumatra has become controversial. For a long time, ore deposits in the Indonesian Island Arc are always identical with the porphyry and hydrothermal processes related to arc magmatism. This paper is dealing with the geology of Latong and its base metal deposits. This work is also to interpret their genesis as well as general relationship to the regional geology and tectonic setting of Sumatra.

The Soripesa prospect area is located at Maria village, Wawo district, Bima region in the East Sumbawa Island, Indonesia. Lithology is dominantly composed of a lithic-crystal tuff of andesitic and dacitic composition and bedded limestone. The polymetallic epithermal quartz veins are hosted by andesitic volcaniclastic rocks. Within these veins, multiphases, colloform-crustiform, bedding to massive textures with pyrite, sphalerite, galena, chalcopyrite, chalcocite, azurite, and malachite are observed. Selected samples were analyzed by using ore microscopy and SEM-EDX. Ore minerals show replacement, ex-solution, colloform, and zonal textures. The paragenesis diagram was made from a careful study of polished sections and thin sections. Textures of ore minerals such as banded, exsolution, replacement, and zone, have been interpreted to correspond to the order of deposition. In pyrite, the average content of Co (0.45 wt.%) is higher than Ni content (0.14 wt.%) and it means that their origin may be hydrothermal origin. Average content ratio, Co:Ni is 2.81. Galena shows a low Ag content of 0.07 %in average. But they show a high Au content of 1.48 %in average. Sphalerite shows a low Fe content of 1.04 %in average and occasionally chalcopyrite inclusion/disease also occurred. Ga and Ge contents are also high in sphalerite. Co>Ni in pyrite, low content of Ag in Galena, low content of Fe and mole % FeS in sphalerite, high content of Ga and Ge, and log (Ga/Ge) in sphalerite, show that pyrite, galena, and sphalerite from Soripesa prospect area were formed under low temperature condition of hydrothermal fluid. Keywords: Ore textures, paragenesis, deposition, hydrothermal fluid, low temperature

Zinc exists as smithsonite and hemimorphite in the lead flotation tailings from the Dandi mineral processing plant in north western Iran. In this research, zinc-rich tailings produced in the Dandi plant were characterized mineralogically and a leaching study was carried out to assess the effect of several parameters on the kinetics of zinc dissolution. Parameters studied included: sulfuric acid concentration, reaction time, temperature and slurry density. It was found that leaching is controlled by a single rate-controlling step with an activation energy of 23.5 kJ/mol. To overcome some of the filtration problems associated with polymerization of silicic acid, lime was added as a coagulant. The optimum pH, holding time and temperature required to maximize the filtration rate were determined.

The Vazante Group, located in the northwestern part of Minas Gerais, hosts the most important zinc mine in Brazil, the Vazante Mine, which represents a major known example of a hypogene nonsulfide zinc deposit. The main zinc ore is represented by willemite and differs substantially from other deposits of the Vazante-Paracatu region, which are sulfide-dominated zinc-lead ore. The age of the Vazante Group and the hosted mineralization is disputable. Metamorphosed mafic dikes (metabasites) that cut the metasedimentary sequence and are affected by hydrothermal processes recently were found and may shed light on the geochronology of this important geological unit. Zircon crystals recovered from the metabasites are xenocrystic grains that yield U–Pb conventional ages ranging from 2.1 to 2.4 Ga, so the basement of the Vazante Group is Paleoproterozoic or has metasedimentary rocks whose source area was Paleoproterozoic. Pb isotopes determined for titanite separated from the metabasites have common, nonradiogenic Pb compositions, which prevents determination of their crystallization age. However, the Pb signatures observed for the titanite crystals are in agreement with those determined for galena from the carbonate-hosted Zn–Pb deposits hosted by the Vazante Group, including galena from minor sulfide ore bodies of the Vazante deposit. These similarities suggest that the metalliferous fluids that affected the metabasites may have been those responsible for galena formation, which could imply a similar lead source for both nonsulfide and sulfide zinc deposits in the Vazante–Paracatu district. This common source could be related to deep-seated, basin-derived, metalliferous fluids associated with a long-lived hydrothermal system related to diagenesis and deformation of the Vazante Group during the Neoproterozoic.

This study investigates the bioleaching of the complex Pb/Zn ore/concentrate using mesophilic (at 30 °C), moderate (at 50 °C), and extreme thermophilic (at 70 °C) strains of acidophilic bacteria. The effects of bacterial strain, pH, iron precipitation, and external addition of Fe2+ on the extraction of zinc were evaluated. The results have shown that the ore is readily amenable to the selective extraction of zinc and lead using the acidophilic strains of bacteria [i.e., majority of lead (>98%) reports to the residue]. Moderate thermophiles displayed superior kinetics of dissolution of zinc compared with the other two groups of bacteria. The pH was found to exert a profound effect on the leaching process controlling the bacterial activity and precipitation of ferric iron mainly as K-jarosite. The K+ released presumably from the alteration of the silicate phases such as K-feldspar present in the ore appeared to promote the formation K-jarosite in moderately thermophilic leaching systems. The external addition of iron was shown to be required for the bacteria to efficiently drive the extraction of zinc from the bulk concentrate. These findings place the emphasis on the prime importance of ferric iron for the dissolution of zinc and of mineralogical properties (i.e., iron and silicate content) of an ore/concentrate to be treated via bioleaching processes.

A study has been undertaken on the bacterial and ferric sulphate leaching of sphalerite, with the aim of observing the relative importance of both diffusion and reaction control, across a range of operating conditions. To facilitate this kinetic analysis a mixed-control rate equation was developed based upon the shrinking particle and shrinking core models, featuring both an intrinsic rate of zinc extraction and a product layer diffusion coefficient. The ferric sulphate oxidation of a pure sphalerite sample was first studied, and the process was found to be mainly controlled by surface diffusion, thought to be due to formation of the elemental sulphur product layer. The mesophilic bacterial oxidation of a high-grade zinc ore was studied at 35 °C, and the process was observed to be controlled by both chemical reaction and diffusion. However, during the mesophilic bacterial oxidation of a low-grade zinc ore at 25 °C, diffusion was found to be rate limiting. It was proposed that this diffusion resistance arises from an unreacted layer of gangue material.

The chalcopyrite bioleaching mechanism was studied to determine its direct or indirect nature. At the same time, a study of possible causes that diminish the dissolution rate and inhibit the attack of this sulphide mineral was carried out. An electrochemical study of the mineral was also performed, which included the elimination or dissolution of possible diffusion barriers formed on the mineral surface. Results of these studies showed that the oxidation state of the dissolved iron (Fe3+) was fundamental to chalcopyrite bioleaching because Fe3+ controlled the relative rate of the oxidation reactions. In addition, the attack of chalcopyrite was controlled by elemental sulphur and intermediate, nonstoichiometric, copper sulphides forming on the chalcopyrite surface, which are less reactive than the original sulphide. Intermediate sulphides caused an important barrier effect at low temperature (35 °C). At higher temperature (68 °C), these intermediate sulphides do not constitute a diffusion barrier due to their dissolution. Microbial attachment to the pyritic phase of the copper ore was related to the dissolution rate of the mineral due to the liberation of Fe2+ after the attack of the pyrite by contact bioleaching. It was concluded that the bioleaching of chalcopyrite concentrate is a cooperative effort involving the simultaneous contact bioleaching of the pyritic phase of the mineral, possibly by an indirect mechanism via thiosulphate, and the indirect bioleaching of chalcopyrite, probably by a mechanism by way of polysulphide and elemental sulphur.