Extraction Of Zinc Research Articles

Carbon-Free Selective Extraction of Zinc and Lead from EAF-Dust

In electric-arc furnace dust, zinc content can reach 43%, lead and content can reach 4%. The ecotoxicant content such as dioxins and furans (D&F) adsorbed on dust particles achieve 500 ng/kg of dust. Generally, zinc and lead are reduced from their oxides by dint of carbon (an average of 500 kg/t dust). The results of thermodynamic calculations and experimental studies have shown that these metals can be extracted from dust without the participation of carbon or at its low content (less than 3%) [1]. Temperature of about 1400 K is required to extract lead, and about 2000 K is required for zinc extraction. The temperatures of their extraction depend on the dust composition, in particular, on the carbon content, chlorine and the O/C ratio [2]. They can also depend on phase and dispersed dust composition. A physicochemical analysis of the dust formation processes in electric arc furnaces (EAF) has been carried out, the composition and properties of dust have been investigated, and experimental studies of the zinc and lead selective extraction process in laboratory conditions have been leaded. A dust processing technology has been developed and the possible innovative potential of the expected results has been assessed. The approaches are based on the study of a continuous two-stage process of carbon-free and zinc and lead selective extraction from EAF dust of different composition. One of the main results of the work, along with the creation of a technology that ensures the selective zinc and lead extraction up to 99%, is the development of a process for neutralizing EAF dust from D&F to an environmentally safe level.

Experimental Study on the Dissolution Behavior of Calcium Fluoride

The presence of halogens has an adverse effect on the zinc extraction process through electrowinning, the last phase of the RLE (Roasting, Leaching and Electrowinning) zinc extraction route. Fluoride (F−) may be present as calcium fluoride (CaF2) and this is, for example, the case in double leached Waelz oxide (DLWO). Efficient removal of F− from primary and secondary raw materials for zinc extraction results in a simplified process and increases flexibility in the selection of raw materials. Understanding of the solubility behavior of pure CaF2 can give valuable information on treatment for maximized halogen removal. Dissolution of CaF2 was studied with the addition of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3). Dissolution studies were combined with thermodynamic calculations to understand the solubility behavior of CaF2 under different conditions. Results from the experiments and the thermodynamic calculations show that Na2CO3 and NaHCO3 have similar behavior if the pH is controlled at the same value. The available carbonate (CO32−) ion in the system limits the concentration of calcium (Ca2+) ion by precipitation of CaCO3, which enhances the dissolution of CaF2. At higher temperatures and pH, calcite, vaterite, and aragonite were formed and co-precipitation of CaF2 along with calcium carbonate (CaCO3) was observed. At lower temperatures and lower pH levels, only calcite and vaterite were formed and a coating by CaCO3 on CaF2 was found to hinder complete dissolution reaction. The results of this study indicate that the temperature along with the reagents used for the dissolution tests have a significant impact on the CaCO3 polymorph mixture (calcite, vaterite and aragonite) formation.

STUDY OF LOW TEMPERATURE TECHNOLOGIES OF PROCESSING ZINC CAKES WITH THE METHOD OF THERMO-STEAMING

The paper deals with efficient processing of zinc cakes wiht the method of thermo-steaming, which is intended to additional extraction of zinc and a number of non-ferrous metals, as a basis for increasing the complex using of raw materials.

Poly(styrene)-co-2-vinylpyridine copolymer as a novel solid-phase adsorbent for determination of manganese and zinc in foods and vegetables by FAAS

The aim of this study is to extract zinc and manganese from foods and vegetables using an amphiphilic copolymer adsorbent, poly(styrene)-co-2-vinylpyridine which was synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization from styrene and 2-vinyl pyridine in the presence of a trithiocarbonate and 2,2′-azo-bis isobutyro nitrile (AIBN) in toluene solution under argon at 80 °C. Fourier Transform Infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy were used in the characterization of the obtained copolymer. Under the optimum conditions, several validation variables such as uncertainty measurement, selectivity, robustness, precisions, matrix effects and accuracy were investigated. Taking an adsorption time of 15 min, detection limits of 0.04 μg L −1 and 0.2 μg L−1and 7.9 μg L−1and enrichment factors of 145 and 110 were obtained for Mn(II) and Zn(II), respectively.The method was successfully applied to the analysis of Mn(II) and Zn(II) in foods and vegetables.

Bioleaching of Sulfide Concentrates with Different Copper and Zinc Contents and Evaluation of Bioleach Residue Grade

Bioleaching of sulfide concentrates with different copper and zinc contents using two cultures of acidophilic chemolithotrophic microorganisms, which were grown at 30 and 35°C, was studied. The average leaching rate of copper was shown to be directly dependent on the copper content in the concentrate. The leaching rate of zinc was found to depend not only on the zinc content but also on the copper content. At the same time, the specific leaching rate of copper varied insignificantly (28–45 mg/(g day)), while the change in the specific leaching rate of zinc was much more pronounced (107–319 mg/(g day)) and depended on the metal contents in the concentrates. Under all conditions of bioleaching, the specific rate of zinc extraction into the aqueous phase increased significantly with an increase in the copper content in the concentrates, which indicated galvanic interactions between sulfide minerals. The possibility of the obtainment of the copper concentrates containing negligible amounts of zinc after bioleaching of the concentrates, in which the content of copper exceeded that of zinc and was not less than 10%, was shown. Bioleaching of the concentrates containing more zinc than copper is impractical.

Continuous bio-hydrometallurgical extraction of zinc from a bulk lead-zinc flotation concentrate on a pilot scale

The high interlock between the fine particles of sphalerite and galena in some parts of the Goushfil mine (Isfahan, Iran) ore has significantly reduced the flotation efficiency. According to the acceptable capability of bioleaching in the recovery of metals from the complex mineralogical resources, the feasibility of zinc extraction from a low-grade (34% Zn) bulk flotation concentrate was investigated. The applied concentrate was processed using a large-scale continuous bioleaching system, including three 50 l stirred bioreactors in series. After 15 days, 83% of zinc was recovered by implementing a mixed culture of moderately thermophile bacteria at pH = 1.8 and 15% solid content. In the next stage, 83% of the accompanying iron impurity was removed from the leachate by jarosite precipitation. Then, about 99.9% of zinc was gained by solvent extraction using 25% saponified D2EHPA at pH = 3.5, O/A = 1 at two steps. Consequently, bioleaching, in combination with bulk flotation, can be successfully applied to recover zinc from the complex lead-zinc ore of the examined deposit.

Study on the improvement of the zinc pressure leaching process

The first two-stage zinc pressure leaching plant with 100 kt-Zn/a capacity in China was put into production in 2009, to recover zinc, rare metals, germanium and gallium. However, the total extraction of zinc is limited to just 93% in initial production. To improve the co-recovery of metals, pressure leaching tests were carried out on the first-stage leach residue from the initial flowsheet. The effects of Fe(III) concentration, oxygen partial pressure, reaction time, sulfuric acid dosage, and particle size of the residues were investigated. The results showed that particle size and acid dosage greatly affected the zinc, iron, gallium, and germanium extraction. The particles of size above 74 μm are the main obstacles to improve extraction. Grinding can effectively improve the recovery of the main metals. The zinc extraction can reach 96.7% after grinding the coarse particles (> 74 μm) prior to leaching. The extraction of other metals are 84.7%, 81.7% and 81.4% for iron, gallium, and germanium, respectively. The total recovery of the two-stage leaching is 98.2%, 90.0%, 86.3% and 87.8% for zinc, iron, gallium, and germanium, respectively.

Multiple regression analysis for the prediction of extraction efficiency in mining industry with industrial IoT

Manufacturers and industrialists have a significant opportunity at hand in automation for the complex processes involved in manufacturing rather than labor-intensive based system analysis and control. Especially industrial IoT (IIoT) technology provides far more intricate details to the industrial automation for prompt decisions automatically through a web server. Hence in this present work, online data monitoring of important attributes associated with the mining industry during the extraction of zinc and lead are analyzed using IIoT. The real-time analysis of the extraction efficiency rate of zinc and lead concerning temperature, pH and a particle size parameter in mining sectors is carried out by storing data in the cloud. It is accomplished by using an integrated IoT module holding Revolution-Pi IIoT (IIoT) gateway with AC500 PLC to afford enhanced data communication from the mining field to the cloud server to increase the performance of the processes. Based on the retrieval of historical data from the cloud, a multivariate regression model for extraction efficiency of zinc and lead is formulated by using pH, temperature and particle size as influencing parameters to estimate the predictions.

Оценка технико-экономической эффективности пирометаллургической технологии переработки пылей электросталеплавильного производства

An evaluation of technical and economic efficiency parameters of a previously proposed technological solution for processing dust from electric steel production by the pyrometallurgical method is presented. The technological approach consists in the reduction of iron and zinc from their oxygen-containing forms (ZnFe 2 O 4 and ZnO) by active carbon-containing materials. Experiments were carried out on samples with a 26.02 and 37.7%wt. of ZnO and Fe 2 O 3 , respectively, to evaluate the processing of industrial dust of PJSC Magnitogorsk Iron and Steel Works in a laboratory facility based on the LHT 08/17 high-temperature furnace (Nabertherm, Germany). "Small long-flame nut" brand charcoal was applied as a carbon reducing agent, with lime and quartz sand serving as sources of slag-forming components. Commercial products were obtained in the form of granular cast iron (96.75 and 2.92%wt. of Fe and C, respectively) and a zinc oxide product (90.21%wt. of ZnO). The extraction of iron and zinc in cast iron comprised the values of 94.0 and 91.0%, respectively. As a result, an annular hearth furnace is recommended as the main technological unit for the industrial implementation of the process. The basic technological scheme is proposed including dosing raw materials, preparing charge briquettes, performing reduction smelting, separation of smelting products (cast iron and slag) and trapping zinc-containing sublimates. To assess the technical and economic efficiency of the developed technology on an industrial scale, the costs of building a dust processing plant involving one annular furnace with an average diameter of 12 m having a steel production capacity of 15 000 tonnes per year were taken into account. The proposed technology was shown to be capable of supporting commercial granular cast iron and zinc oxide products in the amount of 33264 and 4435 tonnes per year, respectively. Considering the investment period, the estimated payback period is determined to be 34 months with the expected net profit equal to 535.59 million rubles/year.

RESEARCH ON COPPER-67 SEPARATION OBTAINED BY PHOTO-NUCLEAR FROM ZINC OF NATURAL COMPOSITION

In the world, it is planned to produce promising for the manufacture of radiopharmaceuticals of radioisotope copper-67 by the reaction of its production from zinc-68 under the influence of γ-radiation on an electron accelerator. The next major issue is the separation of copper and zinc. Extraction, ion exchange and thermal distillation of zinc have already been studied in detail. Co-precipitation of copper with low zinc and thermal distillation of organic compounds of metals is promising.

Impact of Foliar Application with Iron, Zinc, Silicon Nano Particles and Yeast on Growth, Yield and Water Use Efficiency of Tomato Plants under Water Stress Conditions تأثیر الرش الورقی بجزیئات نانو الحدید والزنک والسیلیکون والخمیرة على النمو والمحصول وکفاءة الاستهلاک المائى لنباتات الطماطم تحت ظروف الإجهاد المائى

Two filed experiments were conducted during the two summer seasons of 2015 and 2016 in a private Farm at Gemiana village near Belqas City Dakahlia Governorate, Egypt, to study the effect of interaction between deficit irrigation water (60%, 80%, 100% of ETc) and some foliar spray treatments (nano iron, nano zinc, nano silicon and yeast extract) on plant growth parameters, chemical composition of leaves as photosynthetic pigments (Chl. a, Chl. b, total Chl. a+b), leaf mineral percentages (N, P, K) proline, yield and water use efficiency (WUE) of tomato plants (Fayruz hybrid) under drip irrigation system. A strip-plot design with three replicates was used. The vertical plots were allocated to the deficit irrigation, whereas the horizontal-plots were devoted to foliar spray treatments. Results revealed that the interaction among irrigation tomato plants at the level of 80 % Etc and spraying with different nano particles at different concentration or yeast extract significantly increased all aforementioned parameters, meanwhile deficit irrigation water treatments improved leaves proline content and WUE in both growing seasons. The best interaction treatment for increasing plant growth parameters, chemical constitutes of leaves as photosynthetic pigments (Chl. a, Chl. b, total Chl. a+b) leaf mineral percentages (N, P, K) early and total yield is irrigation treatment with 80 % Etc and spraying with nano Si at 12 ppm and can be recommended to increase growth and productivity tomato plants of under similar conditions of this study.

Recovery of Metal Values from Ni-Cd Cake Waste Residue of an Iranian Zinc Plant by Hydrometallurgical Route

This paper concerns the development of an environment-friendly hydrometallurgical flowsheet dedicated to the recovery of zinc and nickel from a waste residue collected from an Iranian zinc plant. In particular, valuable metals from Ni-Cd cake waste generated at this plant were recovered by a simple hydrometallurgical process using minimum acid for leaching, and solvent extraction step was designed such that addition of sodium hydroxide was not required and the effluent generated is safe to dispose off. The waste was leached with a mixture of hydrochloric acid and sulfuric acid in the presence of hydrogen peroxide in order to achieve a good selectivity towards iron and calcium. Afterwards, cementation was performed at pH 5 in order to remove cadmium. Liquid–liquid extraction was then implemented to produce high-purity solutions of zinc and nickel. Zinc-nickel separation was obtained at pH 2 by using a mixture of bis-(2-ehtyl-hexyl)-phosphoric acid (HDEHP) and tris-2-ethylhexyl amine (TEHA) diluted in an aliphatic kerosene. TEHA did not directly participate but helped in the extraction of zinc by scavenging the protons released by HDEHP. Therefore, no alkaline solution was necessary for maintaining the equilibrium pH during liquid–liquid extraction. Finally, this flowsheet allowed to recover more than 95% of zinc and nickel from the residue with more than 99% purity.

Features of Zinc Extraction from Sulfide Forms

Zinc can be found in oxide and sulfide forms in technogenic formations. Zinc oxide extraction from technogenic formations is widely used in industry. Removing zinc sulfide from technogenic formations is difficult and is currently almost never used. In the present work, the physicochemical features of zinc extraction from sulfide are considered. Process thermodynamic features and possible ways to extract zinc sulfide are shown. Also, ways of valuable commercial products, obtaining from the roasting products, are considered.

Phyto-extraction of zinc, lead, nickel, and cadmium from a zinc leach residue

Zinc leach residue is one of the substantial industrial wastes containing large quantities of heavy metals, releasing toxic elements into the environment. Phyto-extraction was applied to extract zinc, lead, nickel, and cadmium by Amaranthus retroflexus plant. Through three stages of screening, soil amendment, and modification, the bio-concentration factor, weight of biomass, and lifetime of Amaranthus retroflexus were enhanced. Due to the high salinity of the residue, following screening tests, mixture of 25 wt% zinc leach residue +75 wt% soil, was determined as the optimum condition. For further reduction of the salinity, the soil amendment was carried out both by draining and leaching of the residue with distilled water. In the leached condition, the plant illustrated better results. Finally, soil modification was performed by adding two levels of citric acid (0.005 M and 0.1 M) to the previous optimum conditions. Using the lower level of citric acid, bio-concentration factor of zinc, lead, nickel, and cadmium were obtained as 0.6838, 0.3042, 1.1027, and 2.3621, respectively and the plant survived 5 weeks. Phyto metal extraction index (ratio of concentrations of metal in dried plant to concentration of metal in tailing) for zinc, lead, nickel, and cadmium at the final optimum condition were obtained as 17.09%, 7.60%, 27.57%, and 59.05%, respectively. The separation factors showed that Amaranthus retroflexus’s tendency to extract heavy metals was in ascending order for lead, zinc, nickel, and cadmium.

Lowering the Energy Consumption of Zinc Electrowinning By Electrocatalysis of Oxygen Evolution Reaction Using Manganese Oxides

Zinc has a wide range of commercial applications including but not limited to galvanizing iron and steel and production of various metal alloys such as brass and bronze. In hydrometallurgical processes, zinc electrowinning from sulfate-based electrolytes is the last step of zinc extraction in which high purity metallic zinc is electrodeposited from a highly acidic solution on an aluminum cathode. The electrowinning stage is very energy-intensive and responsible for approximately 80% of the power requirement of a zinc refinery (1). Thus, improving the energy efficiency and lowering the operating costs of zinc electrowinning are of primary significance. The oxygen evolution reaction (OER) overpotential on conventional lead-silver (Pb-Ag) anodes contributes to nearly 25% of the total electrowinning cell potential (2). Therefore, the high anodic OER overpotential places a heavy financial burden on zinc refining plants.The present study aims to evaluate novel anodic electrocatalysts incorporating MnO x in order to lower the anodic OER overpotential of the zinc electrowinning process. Anodically electrodeposited MnO x catalysts on Pb-Ag electrodes were prepared using galvanostatic and potentiodynamic polarizations. The OER catalytic activity and stability of MnOx electrodeposited Pb-Ag electrodes were evaluated in 160 g/L sulphuric acid solution with 3 g/L of manganese (II) and in the absence and presence of 0.3 g/L of chloride ion at 35°C, using a standard three-electrode setup. The electrolyte composition and operating conditions were selected such that to be directly applicable to the industrial zinc electrowinning process. The OER activity of the MnOx electrodeposited electrodes was investigated through potentiodynamic polarization and 72-hour galvanostatic electrolysis at 50 mA/cm2 superficial current density. Finally, the activity of MnOx electrodeposited Pb-Ag electrodes was explored in a full zinc electrowinning cell through 24-hour galvanostatic electrolysis at 50 mA/cm2 superficial current density.The OER potential variations of the bare Pb-Ag and MnO x electrodeposited Pb-Ag anodes during the 72-hour galvanostatic polarization are shown in Fig. 1. In the absence and presence of chloride ions, the three MnO x electrodeposited Pb-Ag electrodes are observed to reduce the anodic potential by maximum of 150 mV and 90 mV, respectively. Investigation of these novel electrodes in the full-cell zinc electrowinning operation corroborated the half-cell experiments, revealing a maximum of 80 mV reduction in cell potential at 50 mA/cm2 superficial current density and in the presence of 0.3 g/L of chloride ion. Thus, this work demonstrates that MnO x electrodeposited Pb-Ag anodes have great capacity to lower the power consumption of the zinc electrowinning process.Fig. 1. OER activity and stability comparison under galvanostatic polarization for four anodes: bare Pb-Ag (baseline) and three MnOx electrodeposited Pb-Ag anodes prepared via linear scan voltammetry (LSV), constant current density (CCD), and cyclic voltammetry (CV). Superficial current density: 50 mA/cm2. Electrolyte:160 g/L H2SO4 with 3 g/L Mn2+ and 0.3 g/L Cl- at 35°C.

Dispersive micro-solid-phase extraction using chitosan/polymethacrylate/clay bionanocomposite followed by UV–Vis spectrophotometry for determination of zinc

A novel chitosan-poly(methacrylate)-clay (CTS-pHEMA-MMT) superabsorbent bionanocomposite was prepared by radical copolymerization method and characterized by Fourier-transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction analysis and scanning electron microscopy. The CTS-pHEMA-MMT composite was applied as a sorbent in dispersive micro-solid-phase extraction (D-µ-SPE) of zinc before its spectrophotometric determination after eluting with 4-(2-pyridylazo) resorcinol solution. Under the optimized experimental conditions, the developed D-µ-SPE method with aqueous standard Zn solutions presented a linear working range from 10 to 1000 ng mL−1 with a correlation coefficient of 0.996, a detection limit of 3.1 ng mL−1 and a relative standard deviation better than 3.5% (n = 5) for 10 ng mL−1 and 50 ng mL−1 of Zn(II). The preconcentration factor and the sorption capacity of the synthesized sorbent for zinc were 100 and 5.04 mg g−1, respectively. The recoveries for zinc in tap water, drinking water, milk, butter, and vitamin tablet samples were obtained in the range of 93.7–102.5% for spiked 10 ng mL−1 and 50 ng mL−1 of Zn(II).

In-situ XRD study of the structure and electrochemical performance of V2O5 nanosheets in aqueous zinc ion batteries

Rechargeable zinc ion batteries that use mild aqueous electrolyte are attracting extensive attention for large scale energy storage due to cost and safety concerns. However, the research for the suitable cathode materials in which host zinc ions reversibility insert and extract is still under developing. In this work, we report V2O5 nanosheets as cathode material for zinc ion battery with mild aqueous ZnSO4 electrolyte. The V2O5 nanosheets were synthesized by freeze-drying process using sol-gel as precursor. The structures and morphology of the materials were characterized by XRD and FESEM analysis. FESEM demonstrated that the sample displayed leaf-like sheet morphology. The XRD was indexed to an orthorhombic V2O5 phase. The electrochemical performance of V2O5 nanosheets cathode in aqueous zinc ion battery was measured by galvanostatic charge-discharge test and cyclic voltammetry. As a result, the cathode delivered a maximum specific discharge capacity of 318.4 mAh g−1 at a current density of 1.0 A g−1 and a long cycle life up to 2000 cycles. Meanwhile, in-situ and ex situ XRD analysis showed that the structure of V2O5 nanosheets underwent an irreversible phase transformation after the initial charge and discharge process.

Mineralogical and Chemical Characteristics of Slags from the Pyrometallurgical Extraction of Zinc and Lead

The slags derived from the fire refining of lead bullion, differ distinctly in the mineral composition, which results from the fact that these slags are end products of a series of chemical reactions (of both reduction and oxidation). The most common phases included in the refining slags are sulphates and hydrated sulphates (anglesite, gypsum, ktenasite and namuvite), oxides and hydroxides (wustite and goethite), nitrates (gerhardtite) and silicates (kirschsteinite and willemite). The other phases are sulphides and hydrated sulphides (sphalerite and tochilinite), metals (metallic Pb) and glass. Among the mineral components of these slags can be distinguished—primary mineral constituents, phase constituents formed in the ISP process and lead refining, secondary mineral constituents, formed in the landfill. The slags contain, in chemical terms, mainly FeO, CuO and SO3, PbO, in smaller contents SiO2, Al2O3 and CaO, TiO2, MnO, MgO, K2O, P2O5. The mineralogical and chemical composition indicate that slags may be a potential source of metals recovery and pyrometallurgical processing of these wastes seems to be highly rational.

Comprehensive use of products generated during acid leaching of basic oxygen furnace sludge

A novelty process based on acid leaching basic oxygen furnace sludge by means of medium of 2,5M H2SO4 and 1M HCl was proposed. The new medium used in the study leaches franklinite ZnFe2O4 present in the tested sludge, which is hardly soluble in weak sulphuric acid solutions and well soluble in HCl solutions. This allows for 100% zinc extraction from the basic oxygen furnace sludge. The component of the leaching medium in the form of a sulphuric acid solution transforms the calcium compounds contained in the basic oxygen furnace sludge into insoluble calcium sulphate. The study examined the effect of solid to liquid ratio S/L (g/mL), temperature, time and rotational speed of stirrer on zinc and iron extraction from the sludge. Optimal leaching conditions were: t = 120 min, T = 60 °C, n = 500 min−1, S/L: 0.2. The leached solid filtration product obtained after leaching, dried and magnetically processed is separated into pure iron-bearing concentrate, which contains 77% Fe3O4 and 23% Fe2O3 and calcium sulphate waste. Their composition is confirmed by the X-ray diffraction analysis. The use of ethyl alcohol to precipitate sulphate iron compounds is a new alternative to recover and reuse the precipitant. The pure iron sulphate compounds with different hydration are obtained, which is confirmed by the X-ray diffraction analysis. The utilitarian aim of the study was to specify technological guidelines of the presented process and its material balance. Acid leaching of basic oxygen furnace sludge helps solve the problem of lack of selectivity in acid leaching of zinc and iron. This suggests the possibility of comprehensive use of the obtained products.

Direct Acid Leaching of Sphalerite: An Approach Comparative and Kinetics Analysis

The present work reports the direct leaching of zinc from a sphalerite concentrate in acid media. Lab-scale and pilot-scale experiments were conducted in atmospheric-pressure and low-pressure reactors, respectively. Leaching of zinc and precipitation of iron was achieved in the same stage using different reagents like Fe3+, O2, O3, and Fe2+ (which is continuously oxidized in the leaching solution by H2O2 and O2). The highest percentage of zinc extraction (96%) was obtained in pilot-scale experiments using H2SO4, Fe2+, and O2. Experimental results were compared with those of other researchers to provide a better understanding of the factors influencing the dissolution of zinc. In the first instance, it was determined from analysis of variance that leaching time and the use of an oxidant agent (O2 or O3) were the most influential factors during the direct leaching of zinc from the sphalerite concentrate. Kinetic models were also evaluated to determine the rate-limiting step of the sphalerite leaching; it was concluded that the type of the sulfur layer formed in the residue (porous or non-porous) depends on the type of the oxidant used in the leaching media, which determines the dissolution kinetics of zinc.