Zinc Ore Research Articles

Zinc leaching from smithsonite ore in lactic acid solution: Studies on parametric optimization, kinetic and mechanism

ABSTRACT. The solubility of low-grade zinc ores with a selective leaching environmentally friendly reagent has become a focus of great interest since zinc and its compounds have found wide application. For this purpose, lactic acid was used to investigate the selective leaching kinetics of smithsonite ore obtained from Kayseri region. The effects of particle size (137.5-725 µm), acid concentration (0.5-5 M), solid/liquid ratio (0.5/250-3/250 g mL-1), stirring speed (500-800 rpm) and temperature (40-70 °C) parameters on the smithsonite dissolution rate were experimentally studied. The results obtained show that leaching of about 99.8% of zinc is achieved using 425 µm particle size at a reaction temperature of 70 °C for 45 min reaction time with 2 M lactic acid, the solid/liquid ratio of 1/250 g mL-1 and stirring speed of 600 rpm. The statistical analysis of the experimental data obtained from the parameters revealed that smithsonite dissolution was the surface reaction-controlled with an apparent activation energy of 53.62 kJ.moL-1. The kinetic model describing the process was found as 
 
 KEY WORDS: Smithsonite, Dissolution kinetics, Lactic acid, Zinc lactate
 Bull. Chem. Soc. Ethiop. 2023, 37(3), 735-744. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i3.15

Temperature Dependence of Metals Accumulation and Removal Kinetics by Arabidopsis halleri ssp. gemmifera.

Cadmium (Cd), which is present in zinc (Zn) ore, is a toxic metal and causes contamination globally. Phytoremediation is a promising technology for the remediation of sites with low and moderate contamination. Temperature is an important factor in phytoremediation because it has an impact on both plant biomass and the accumulation of heavy metals. However, little is known about the influence of temperature on heavy metal accumulation by the Cd and Zn hyperaccumulator Arabidopsis halleri ssp. gemmifera. The effect of temperature on the distribution of Cd and Zn in A. halleri ssp. gemmifera and the mechanism of metal removal from solution were investigated in this study. Our results showed that the temperature dependence of the distribution of Cd and Zn in the plant was different, which may suggest that the mechanisms of xylem loading were different between Cd and Zn. Although Cd and Zn have partially similar transport pathways, the removal kinetics based on the first-order reaction rate constant revealed that the temperature which maximized rate of absorption was different between Cd and Zn. This study suggests a potential for efficient Cd phytoextraction using A. halleri ssp gemmifera in Cd and Zn co-existing environments.

Application of the Microwave and Ultrasonic Combined Technique in the Extraction of Refractory Complex Zinc Ore

This paper proposes a combined microwave and ultrasonic technique that aims to extract the refractory mineralogical properties of complex zinc ore. This technique consists of two steps: microwave-assisted phase transformation and ultrasonic-assisted complexation leaching. During the microwave-assisted phase transformation step, the refractory zinc phases transform into manageable phases using doping oxidation agents. In the ultrasonic-assisted complexation leaching step, the effect of NTA3 on Zn2+ species distribution is explored. The results show that microwave roasting with 20% Na2O2 at 600 °C for 15 min adequately transforms ZnS, ZnCO3 and Zn2SiO4 into ZnO and avoids the generation of Zn2SiO4. Further, 0.5 mol/L NTA3− (nitrilotriacetic acid) is especially effective as a complex additive for complexes with Zn2+ as Zn (NTA)24−. The ultrasonic technique can reduce the diffusion resistance and open the products in the leaching process, improving zinc leaching by 4.7%. The degree of zinc recovered from zinc ore can reach 91.4% when leach is assisted with 225 W ultrasonic force at 80 °C for 75 min. This paper shows great potential for the green extraction of non-traditional zinc-containing resources.

S-wave velocity characteristics and mineralization of the southern tibet detachment system-yalaxiangbo dome

A series of extensional structures, including the southern Tibet detachment system (STDS), the north-south trending rifts (NSTR), and the northern Himalayan gneiss dome (NHGD), developed from the collision and compression between the Indian and Eurasian plates. These tectonic movements were accompanied by magmatism and polymetallic mineralization. Cuona Rift (CR) is located on the STDS next to the Yalaxiangbo Dome (YD) and passes through the Zhegucuo-longzi fault (ZLF), the Lhozhag fault (LZF), the Rongbu-Gudui fault (RGF), the Cuonadong dome (CD), and the YD. The study area contains numerous metal deposits, such as rare metal ore, lead zinc ore, gold deposits, and two geothermal fields, i.e., the Cuona geothermal field (CGF) and the Gudui geothermal field (GGF). Current research on the geological structures from the STDS to the YD is mainly based on magnetotelluric and natural seismic imaging. These surveys have a low resolution, making it impossible to image the shallow crust in detail. This study obtained about a 112 km S-wave velocity profile from the STDS to the YD using the multichannel surface wave imaging method. The profile results indicated that the average thickness of the sedimentary layer from the STDS to the YD is 400–500 m, while it is more than 800 m at certain fault zones. The CD is connected to the high-velocity body below the Zhaxikang ore concentration area (ZOCA) and may have the same provenance. The thermal conductivity reveals that the CGF, the GGF, and the ZOCA have high values and a more intense thermal radiation capacity. This drives the migration and circulation of the thermal fluids in the CGF and the GGF, causing them to continuously transmit heat to the shallow surface along the fault system. The migration of the thermal fluids extracts useful elements from the geological bodies through which it flows. When these elements mix with the atmospheric infiltration water, it precipitates to form the Zhaxikang hydrothermal superimposed transformation type lead-zinc polymetallic deposit.

Zinc ore supplier evaluation and recommendation method based on nonlinear adaptive online transfer learning

<p style='text-indent:20px;'>Purchasing decisions determine the purchasing cost, which is the largest section of the production cost of zinc smelting enterprise(ZSE). An excellent supplier recommendation is significant for ZSE to reduce the cost. However, during the supplier recommendation process, the nonlinear demand feature of purchasing department varies with the production environment, and there are wrong samples that can affect the supplier recommendation effect. To handle these problems, the recommendation strategy based on a multiple-layer perceptron adaptive online transfer learning algorithm(AOTLMLP) are proposed. In this method, the original prediction function is modified based on MLP nonlinear projective function and adaptive loss function, which enables the AOTLMLP algorithm to tackle the nonlinear classification problems and efficiently follow the demand change of purchasing department, thereby improving the result of the recommendation. The performance of the AOTLMO algorithm is evaluated through a common dataset and a purchasing dataset from a zinc smelter that generated by a supplier evaluation model. It can be assumed that AOTLMLP can ignore the influence of wrong samples and provide an effective recommendation confronting the characteristic of zinc ore purchasing.</p>

Stability analysis of the integrated waste dumps of the open pits Žuta Prla and Brskovo near Mojkovac

The lead and zinc ore are expected to be mined at the open pits Žuta Prla and Brskovo near Mojkovac, Montenegro. During ore mining and flotation processing, the waste from the open pits and tailings from pre-concentration (DMS) and flotation tailings are produced. Two integrated waste dumps are planned in the immediate vicinity of the open pits for disposal of these materials. This paper presents the geotechnical tests of the base of these waste dumps, as well as the tests of deposited materials, and calculation of their stability in accordance with the current legal regulations.

Optimization of magnetic separation of hematite contained in the depressed product from vazante mine s zinc ore flotation

The mining industry has seen a significant decline in mill feed grade in recent years, resulting in an ongoing build-up of materials not recovered at the mineral processing plants whose economic value has not yet been determined. Tailings dams have been the preferred method of disposal of such materials. However, recent dam breach events and the growing demand for mineral goods have enhanced the appeal of a more effective use of mined materials to prevent tailings accumulation and reduce social and environmental impacts, in line with the environmental, social and governance (ESG) principles that most companies have adopted. Different techniques can be used to recover economically valuable minerals contained in such materials, among which magnetic separation stands out for reasons of cost, production capacity, and recent developments of new equipment and matrices for wet high-intensity magnetic separators. The outcome includes gains in capacity, grade, and recovery yield. This paper assessed the use of a matrix developed by the company Gaustec, called BigFlux, in the magnetic separation of depressed product from the flotation process at Nexa Resources’s Vazante mine. Laboratory-scale magnetic separation tests were conducted using standard and an optimized matrix. For a 59% iron concentrate, the metallurgical recovery using such optimized matrix reached 72.6%, up 4% from the figure resulting from the use of the standard matrix, thus indicating that the use of the optimized matrix can improve the magnetite recovery process of the studied material.

Effect of composition of metal-bearing surface modifiers for sulfide minerals of base heavy metals in copper–zinc ore flotation

Effect of composition of metal-bearing surface modifiers for sulfide minerals of base heavy metals in copper–zinc ore flotation

Evaluating the performance of an industrial-scale high pressure grinding rolls (HPGR)-tower mill comminution circuit

This paper presents the commercial implementation of a novel comminution circuit with high pressure grinding rolls (HPGR) followed by tower mill in a copper–lead–zinc ore dressing plant. With a throughput of 650 t/d, the comminution circuit comprises three stages of crushing by a jaw crusher, cone crusher, and HPGR as primary, secondary, and tertiary crushers and one stage of grinding by tower mill. Closed with a flip-flow screen, the HPGR reduces the feed size from −12 to −1 mm, and the tower mill circuit produces a flotation feed with a fineness of 85 % passing 0.074 mm. This comminution circuit has HPGR for partial coarse grinding and uses tower mill to replace the energy-inefficient ball mill for primary grinding. The circuit has been operated for more than 7000 h without the replacement of rolls and is projected to reach its design service life of over 13,000 h. Compared with a conventional dressing plant handling similar ores using an SABC circuit, 20.16 % energy savings and improved separation are realised. Opportunities and considerations for this novel comminution configuration are discussed.

Germanium speciation in experimental and natural sphalerite: Implications for critical metal enrichment in hydrothermal Zn-Pb ores

The critical metal germanium (Ge) is recovered as a by-product of mining other commodities, such as zinc and thermal coal. We investigated the Ge incorporation mechanism in sphalerite synthesized under hydrothermal conditions like those of sediment-hosted Zn-Pb deposits. Sphalerite ± galena ± barite formed via reactions of Ge ± Fe ± Cu ± Ba-bearing brine with calcite and reduced sulfur at 200 °C and water vapor-saturated pressure. The products were examined using backscattered electron (BSE) imaging, electron probe microanalysis (EPMA), electron backscattered diffraction (EBSD), synchrotron X-ray fluorescence (SXRF) and micro-X-ray absorption near-edge structure (μ-XANES). We show that Ge(IV) is incorporated into sphalerite and bonded with reduced sulfur, both in the experimental sphalerite and in natural zinc ore samples from the MacArthur River Zn-Pb-Ag deposits, Australia. Copper K-edge XANES spectra show that copper occurs as Cu(I) in the experimental sphalerite, consistent with previous studies on Cu in natural sphalerite. The experiments reveal that Ge(IV) substitution in sphalerite occurs with and without the presence of other metal ions (e.g., Cu(I)), indicating that Ge(IV) substitution can be accommodated via charge balance by vacancies as well as by coupled substitution in the synthesized sphalerite. Ab initio quantum chemical simulations confirm that sphalerite can readily accommodate Ge, with the crystal structure and average Zn-S, Zn-Zn, S-S distances retained when replacing > 3 mol% of the Zn sites with Ge(IV), Ge(II), Cu(I) or Fe(II), demonstrating the resilience and flexibility of the sphalerite crystal structure. These Ge incorporation mechanisms explain the previous observations of multiple ways of Ge incorporation in natural sphalerite. The study provides experimental and molecular simulation insights for understanding the processes related to the formation and extraction of Ge in zinc ores.

Direct electroseparation of zinc from zinc sulfide in eco-friendly deep eutectic solvent: Highlighting the role of malonic acid

Zinc sulfide (ZnS), one of the main ingredients of zinc ore and emerging materials, partly processes environmental risk. Deep eutectic solvents (DESs) are green solvents to efficiently separate metals with less emission. In this study, a novel route for direct electroseparation of Zn from ZnS in eco-friendly choline chloride-urea DES with the addition of malonic acid (MA) is studied for the first time. The role of MA and the reduction behavior of Zn(II) are systematically analyzed by cyclic voltammetry. The reduction of Zn(II) is quasi-reversible and follows one-step two-electron transfer process. Pure Zn with nanostructure is obtained with the current efficiency of 86.5 % and energy consumption of 2621.8 kW·h·t−1 at the optimized parameters of 10 mA·cm−2, 353 K and 100 mM·L-1 ZnS. Mechanisms analyses indicate that in the presence of 60 mM·L-1 MA, besides [ZnCl−3]- and [ZnCl−5]3-, some ZnS are dissolved to form stable [Zn(MA)2-Cl−2]4-, [Zn(MA)2-Cl-]3- and other MA based ligands, which causes a higher Zn ion solubility of 0.13 mol·L-1 and may promote the subsequent electroseparation of ZnS. Results from this study are expected to propose a simplified route to directly separate Zn from ZnS without oxidation pretreatment to achieve hazardous waste minimization.

Engineering geology and subsidence mechanism of a mountain surface in the Daliang Lead–zinc Ore Mine in China

Engineering geology and subsidence mechanism of a mountain surface in the Daliang Lead–zinc Ore Mine in China

Modeling of Atmospheric Dispersion of Jarosite Particles from Tailing Waste in Mitrovica, Kosovo

Most of the zinc producers in the world use the jarosite process to improve zinc recovery and to remove iron as an undesirable constituent of zinc ores. Jarosite waste released from the zinc extraction process in Mitrovica, Kosovo has led to severe environmental problems due to toxic heavy metals. This industrial waste from the Zn hydrometallurgy process was abandoned on an open field, being exposed to meteorological conditions and aging. The chemical composition and grain size distribution of the jarosite waste deposit was determined. Microwave digestion procedures were used on whole jarosite samples for use in inductively coupled plasma optical emission spectrometry trace metal analysis (ICP-OES). In addition, different weathering conditions were considered for testing the emission rate of the particles in the laboratory, including relative humidity, wind speed, and temperature. Terrain properties, urban infrastructure, source formation, and location were used for modeling with the AERMOD View-Gaussian air dispersion model. The modeling results showed a range of pollution exceeding the maximum limits in an area of 3 km in the conditions of southeast wind direction and wind speed exceeding 10 m s−1, heavily polluting the city of Mitrovica.

Indium Recovery by Adsorption on MgFe2O4 Adsorbents.

Indium and its compounds have many industrial applications and are widely used in the manufacture of liquid crystal displays, semiconductors, low temperature soldering, and infrared photodetectors. Indium does not have its own minerals in the Earth’s crust, and most commonly, indium is associated with the ores of zinc, lead, copper and tin. Therefore, it must be recovered as a by-product from other metallurgical processes or from secondary raw materials. The aim of this study is to investigate the adsorption properties for recovering indium from aqueous solutions using iron–magnesium composite (MgFe2O4). In addition, the results show that the material offers very efficient desorption in 15% HCl solution, being used for 10 adsorption–desorption cycle test. These results provide a simple and effective process for recovering indium. Present study was focuses on the synthesis and characterization of the material by physico-chemical methods such as: X-ray diffraction, FT-IR spectroscopy, followed by the adsorption tests. The XRD indicates that the MgFe2O4 phase was obtained, and the crystallite size was about 8 nm. New prepared adsorbent materials have a point of zero charge of 9.2. Studies have been performed to determine the influence of pH, initial indium solution concentration, material/solution contact time and temperature on the adsorption capacity of the material. Adsorption mechanism was established by kinetic, thermodynamic and equilibrium studies. At equilibrium a maximum adsorption capacity of 46.4 mg/g has been obtained. From kinetic and thermodynamic studies was proved that the studied adsorption process is homogeneous, spontaneous, endothermic and temperature dependent. Based on Weber and Morris model, we can conclude that the In (III) ions takes place at the MgFe2O4/In (III) solution–material interface.

Potential of phytomining in Bulgaria

Phytomining has been gaining more and more popularity in recent years. Scientific information is being accumulated and technologies are being developed that could make phytomining an applicable technology for the extraction of rare and noble metals.In Bulgaria, the mining industry is well developed. Copper, lead, zinc, gold and polymetallic ores are mainly mined. The waste generated during the mining process of these ores has a great potential for phytomining. There are many existing, abandoned and closed dumps, tailings ponds and landfills that have the potential to be used for phytomining.This paper analyzes the possibility of using phytomining technology for the extraction of noble and rare metals in Bulgaria. An overview of the level of development of phytomining technologies and the available resources in Bulgaria for which it is applicable has been made.

Synthesis of zinc oxide derived from wastewater of glove manufacturing via adsorption-desorption-precipitation path

The demand for ZnO significantly increased over the past decades. Extraction and refinement of zinc ores results in the release of hazardous wastes to the environment. In particular, the tremendous demand for disposable nitrile gloves during the Covid-19 pandemic has spiked superior demand for ZnO used as a crosslinking agent in the manufacturing process and leads to the generation of zinc containing wastewater traditionally removed via chemical precipitation. This paper focuses on the application of adsorption for zinc removal which opens an opportunity to recycle zinc to synthesize secondary zinc oxide. This study evaluated the feasibility of zinc oxide synthesis via the adsorption-desorption-chemical precipitation pathway. Palm shell activated carbon (PSAC), a low-cost adsorbent, was used for the removal of zinc from the synthetic and industrial wastewaters. Subsequently, zinc desorption was carried out using 0.3 M HCl. Then ZnO was synthesized from the desorption solutions via chemical precipitation using potassium hydroxide. Average zinc conversion rate of 98 % was achieved in this study. The synthesized ZnO exhibited high surface area of 97.4 m2/g after calcination (400 °C, 3 hr), high purity and crystallinity. The results confirmed the feasibility of zinc ions recovery for recycling to produce secondary good quality zinc oxide.

Calcareous Materials Effectively Reduce the Accumulation of Cd in Potatoes in Acidic Cadmium-Contaminated Farmland Soils in Mining Areas.

The in situ chemical immobilization method reduces the activity of heavy metals in soil by adding chemical amendments. It is widely used in farmland soil with moderate and mild heavy metal pollution due to its high efficiency and economy. However, the effects of different materials depend heavily on environmental factors such as soil texture, properties, and pollution levels. Under the influence of lead–zinc ore smelting and soil acidification, Cd is enriched and highly activated in the soils of northwestern Guizhou, China. Potato is an important economic crop in this region, and its absorption of Cd depends on the availability of Cd in the soil and the distribution of Cd within the plant. In this study, pot experiments were used to compare the effects of lime (LM), apatite (AP), calcite (CA), sepiolite (SP), bentonite (BN), and biochar (BC) on Cd accumulation in potatoes. The results showed that the application of LM (0.4%), AP (1.4%), and CA (0.4%) had a positive effect on soil pH and cations, and that they effectively reduced the availability of Cd in the soil. In contrast, the application of SP, BN, and BC had no significant effect on the soil properties and Cd availability. LM, AP, and CA treatment strongly reduced Cd accumulation in the potato tubers by controlling the total ‘flux’ of Cd into the potato plants. In contrast, the application of SP and BN promoted the migration of Cd from the root to the shoot, while the effect of BC varied by potato genotype. Overall, calcareous materials (LM, CA, and AP) were more applicable in the remediation of Cd-contaminated soils in the study area.

Genesis of the Florida Canyon Nonsulfide Zn Ores (Northern Peru): New Insights Into the Supergene Mineralizing Events of the Bongará District

Abstract The Florida Canyon Zn deposit in the Bongará Province of northern Peru consists of sulfide and nonsulfide mineralizations within dolomitized strata of the Triassic Chambará Formation, a member of the Triassic-Jurassic Pucará Group. The nonsulfide mineralization, which represents one third of the total resource, formed by supergene alteration of Mississippi Valley-type sulfide bodies. The nonsulfide assemblages occur in stratabound or fault-related, discordant zones that mimic the shapes of the former sulfide zones. Two nonsulfide facies can be distinguished: facies 1 – red zinc ores, which are characterized by smithsonite, or hemimorphite-dominant bodies that formed by direct replacement of primary sulfide assemblages, and facies 2 – white zinc ores, which are characterized by masses of colloform smithsonite formed by replacement of wall rock. The facies are distinct in bulk chemical composition and stable isotope geochemistry. Facies 1 shows high concentrations of Zn, Pb, Fe, Ge, Mn, and As, whereas facies 2 shows only high Zn and Cd concentrations. Enrichments in Ge, which have been reported in other Zn deposits of the Bongará Province, are associated with hemimorphite, Fe hydroxides, and remnant sphalerite in facies 1. The δ13C and δ18O signatures of smithsonite in both facies suggest that meteoric waters infiltrating the precursor sulfide bodies were affected by kinetic fractionation and originated from multiple sources at different altitude.

Optimized Neural Network for Research Evaluation of Mineral Resources Carrying Capacity in Southern Shaanxi

Evaluation of the carrying capacity of mineral resources is one of the important research content in the implementation of sustainable development. Based on analyzing the metallogenic geological characteristics, distribution, and resource status of mineral resources in southern Shaanxi, this paper establishes an analysis model of mineral resources and mineral advantages based on the analytic hierarchy process and applies them to evaluate the advantages of mineral resources. To provide optimal and efficient results, an improved model of an artificial neural network based on the bat optimization algorithm has been utilized. Through model analysis, the potential value and carrying capacity of mineral resources in three major prefecture-level cities in southern Shaanxi are comprehensively evaluated and analyzed. The results show that the main dominant minerals in southern Shaanxi are gold, lead zinc, and molybdenum ore. There are three grades of mineral resources carrying capacity: Shangluo City is an excellent grade, Hanzhong City is a good grade, and Ankang City is a general grade.

Distribution, Assessment, and Source of Heavy Metals in Sediments of the Qinjiang River, China.

Heavy metals are toxic, persistent, and non-degradable. After sedimentation and adsorption, they accumulate in water sediments. The aim of this study was to assess the extent of heavy metal pollution of Qinjiang River sediments and its effects on the ecological environment and apportioning sources. The mean total concentrations of Mn, Zn, Cr, Cu, and Pb are 3.14, 2.33, 1.39, 5.79, and 1.33 times higher than the background values, respectively. Co, Ni, and Cd concentrations are lower than the background values. Fe, Co, Ni, Cd, Cr, Cu, and Pb are all primarily in the residual state, while Mn and Zn are primarily in the acid-soluble and oxidizable states, respectively. Igeo, RI, SQGs, and RAC together indicate that the pollution status and ecological risk of heavy metals in Qinjiang River sediments are generally moderate; among them, Fe, Co, Ni, Cd, Cr, and Pb are not harmful to the ecological environment of the Qinjiang River. Cu is not readily released because of its higher residual composition, suggesting that Cu is less harmful to the ecological environment. Mn and Zn, as the primary pollution factors of the Qinjiang River, are harmful to the ecological environment. This heavy metal pollution in surface sediments of the Qinjiang River primarily comes from manganese and zinc ore mining. Manganese carbonate and its weathered secondary manganese oxide are frequently associated with a significant amount of residual copper and Cd, as a higher pH is suitable for the deposition and enrichment of these heavy metals. Lead–zinc ore and its weathering products form organic compounds with residual Fe, Co, Cr, and Ni, and their content is related to salinity. The risk assessment results of heavy metals in sediments provide an important theoretical basis for the prevention and control of heavy metal pollution in Qinjiang River.