Zinc Production Process Research Articles

Evaluation of Mesophilic Species Performance in Extraction of Cobalt and Manganese from Hot Filter Cake of Zinc Processing Plant

ABSTRACT Cobalt, recognized as one of the scarcest industrial metals, is typically discarded during the zinc production process in the high-temperature refining section, along with manganese. This waste product is colloquially referred to as ‘hot cake.’ The present study endeavored to segregate cobalt and manganese from the hot cake and transition them into the liquid phase via bioleaching, a method that is both economically and environmentally superior to pyrometallurgical techniques. In the hot cake, cobalt exists as Co (III) and manganese as Mn (IV). Given their oxidized states, both cobalt and manganese are insoluble in acid and necessitate reduction for dissolution. The study employed Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans bacteria to create an environment conducive to the reduction of cobalt and manganese. Under optimal conditions, this biotechnological approach facilitated the recovery of 62.8% of cobalt and 91.6% of manganese. Subsequently, a model was developed to predict the optimal method for processing cobalt from hot cake, based on the recovery rates of cobalt and manganese. This research contributes to the broader goal of resource recovery and waste minimization in the metal industry.

Providing Practical Instruction for Solving Environmental Problems from Residue (cake) of Cold Purification Process in Zinc Production Process

Background and Objective: In the waste from the cold treatment process in zinc production plants, there is about 40 to 50% of zinc and other harmful heavy metals such as cadmium and nickel. Cadmium and nickel are among the heavy metals that are harmful to human health in high concentrations. Removal of bio-pollutants from these wastes is one of the concerns of the zinc industry. The purpose of this study is to remove nickel and cadmium as impurities in the zinc production process by cementation method. Methodology:The procedure consists of three steps: cold purification cake leaching, impurity purification and electrolysis. The cake is first liquefied with sulfuric acid and the resulting solution contains zinc ions along with nickel and cadmium impurities. Optimal conditions for the removal of impurities were obtained by the surface response method (RSM), then the filtration process was performed by the cementation method and the impurities were removed and finally the solution was electrolyzed to produce zinc. Using Design Expert (DOE) test design software, the parameters affecting the filtration process such as temperature, zinc powder concentration, retention time and additive concentration were investigated. Findings: It was found that most influences related to contact time, temperature, zinc powder amount and additive concentration, respectively. So, optimum conditions for removal of nickel and cadmium containing temperature of 85 centigrade, concentration of 6.63 mg L-1 of zinc powder, contact time of 100 min and concentration of 10.29 mg L-1 for additive were obtained. At these conditions, impurities amounts were reached to the allowed limit for electrolysis and zinc in the cake was recovery. Conclusions: Using cementation method by removing impurities and then recovering zinc, in addition to solving some of the environmental problems caused by the cake, the recovery of these metals is of great economic importance.

Simultaneous removal of Co, Cu, Cd and Ni from zinc sulfate solution by zinc dust cementation

Instead of conventional two or three-stage zinc dust cementation purification, one-stage purification was proposed to remove copper, cadmium and nickel as well as cobalt by CuSb activation simultaneously from solution for an electrolytic zinc production process under development by MMG Limited. Copper was rapidly removed, forming a porous copper shell around a zinc particle. The shell acted as a cathode for the reduction of cobalt, cadmium, and nickel while the zinc particle dissolved anodically. The measurement of hydrogen evolution as well as slurry potential explains how the reduction and re-dissolution of cobalt, cadmium and nickel as a function of time is influenced by temperature, pH, and antimony and zinc dust dosages, providing a deeper understanding of impurity removal. Cobalt, cadmium and nickel were initially removed without back reaction. When zinc dissolved to a certain degree, the shell potential exceeded their redox potentials and the impurities started to re-dissolve. The shell potential was determined by the electrical contact between a zinc particle and the shell, the portion of the remaining zinc and the surface product on the zinc particle. The zinc dissolution weakened the electrical contact and therefore increased the shell potential. Temperature, pH, and antimony and zinc dust dosages not only affect the impurity reduction but also zinc dissolution, the shell potential and finally the impurity re-dissolution in different degrees. Copper, cadmium, cobalt and nickel can be completely removed in one step. The optimal conditions for impurity removal are recommended.

One Step Interface Activation of ZnS Using Cupric Ions for Mercury Recovery from Nonferrous Smelting Flue Gas.

The flue gases with high concentration of mercury are often encountered in the nonferrous smelting industries and the treatment of mercury-containing wastes. To recover mercury from such flue gases, sorbents with enough large adsorption capacity are required to capture and enrich mercury. ZnS is a cheap and readily prepared material, and even can be obtained from its natural ores. In this work, a simple controllable oxidation method-soaking in cupric solution-was developed to improve the interfacial activity of ZnS and its natural ores for Hg0 adsorption. The gaseous Hg0 adsorption capacity of ZnS was enhanced from 0.3 to 3.6 mg·g-1 after such treatment. Further analysis indicated that a new interface rich in S1- ions was formed and provided sufficient active sites for the chemical adsorption of Hg0. In addition, the cyclic Hg0 adsorption and recovery experiments demonstrated that the adsorption performance of spent activated-ZnS was recovered after reactivating sorbents with Cu2+, indicating the recovery of activated interface. Meanwhile, the high concentration of adsorbed mercury at the surface can be collected using a thermal treatment method. Utilization of raw materials from a zinc production process provides a promising and cost-effective method for removing and recovering mercury from nonferrous smelting flue gas.

Clean recycling of zinc from blast furnace dust with ammonium acetate as complexing agents

ABSTRACTBlast furnace dust (BFD) from ironmaking and steelmaking process is important secondary sources of zinc and other valuable metals. To realize recycling utilization of zinc secondary resource, a clean zinc production process using NH3-CH3COONH4-H2O as leaching agent has been developed. It was found that the addition of CH3COONH4 to NH3-H2O system promotes the zinc extraction, and 77.79% (8.23g/L) of Zn could be dissolved. The leaching process is controlled by the diffusion and interface transfer, and the corresponding activation energy Ea is 22.32 kJ/mol. The results of Fourier transforming infrared spectrum (FT-IR) and Electrospray ionization mass spectrometry (ESI-MS) analysis showed that zinc can combine with the carboxylate anion to form Zn-complexes.

Analysing the characteristics and application potentials of jarosite waste in Kosovo

<div> <p>Jarosite waste released from the zinc production process during the hydrometallurgical leaching of concentrates in Trepça lead-zinc smelter, Kosovo has serious environmental problems due to the presence of toxic metals such as Pb, Cd, Zn, As etc. Its disposal in open tailing damps has become a major environmental concern with contamination effects of water, soil and vegetation. The current paper considers the jarosite waste in Mitrovica Industrial Park, Kosovo in order to evaluate the characteristics of jarosite waste, identify the potential environmental impacts and understand its potential for recycling or utilization as a challenge for the development of a positive “green” image environmental protection and sustainable hazard waste management in future. XRD, SEM and TG/DTA were used to analyze the characterization features of jarosite. The results give an initial understanding of the jarosite strengths and application potentials as recycled material. The potential application provides useful contribution towards proper environmental, social and economic management development. </p> </div> <p> </p>

Fluoride removal from Double Leached Waelz Oxide leach solutions as alternative feeds to Zinc Calcine leaching liquors in the electrolytic zinc production process

The most important limitation of leached Waelz Oxide from the pyrometallurgical treatment of Electric Arc Furnace Dust (EAFD) is its high fluorine content. This work deals with the reduction of the harmful effects of the Double Leached Waelz Oxide fluorine content in the hydrometallurgical process for electrolytic zinc production process when it is used as raw material directly in the leaching stage. The resulting process is a purification treatment of Double Leached Waelz Oxide leach solution to remove the dissolved fluoride in this unpurified zinc liquor. Leached fluorides from this liquor are precipitated in order to reduce their concentration until the specified values, avoiding cathode corrosion in the electrowinning cells. In this paper a selective precipitation process to maximize the fluoride removal and to minimize the zinc losses is presented, achieving the industrially specified solution composition when the Zinc Calcine is the used raw material. The formation of aluminium-fluoride complexes and the variation of their solubilities with the pH evolution are the basis of the proposed treatment. In addition, this fluoride removal has also been improved and optimized in order to be integrated in the overall industrial hydrometallurgical process and the obtained results are presented and discussed proving the viability of this improved stage.

Reductive clean leaching process of cadmium from hydrometallurgical zinc neutral leaching residue using sulfur dioxide

Large quantities of cadmium-containing zinc neutral leaching residues (ZNLR) are produced constantly in the electrolytic production of zinc, creating serious cadmium pollution. In order to solve the problem and realize a clean zinc production process, a new reductive cleaning leaching process using sulfur dioxide as reducing agent has been developed, in which the beneficiation of cadmium pollution factor is solved. The cadmium leaching mechanisms were briefly analyzed and the effects of temperature, initial sulfuric acid and partial pressure of sulfur dioxide on the kinetics of cadmium dissolution in the mixed SO2+H2SO4 system was investigated. The order of reaction with respect to particle size, initial sulfuric acid concentration and partial pressure of sulfur dioxide at the fixed liquid/solid ratio and stirring speed were determined as −0.98, 1.49 and 0.51, respectively. Diffraction peak of zinc ferrite or cadmium-bearing zinc ferrite disappeared and the main compositions of the reductive leaching residue were lead sulfate (PbSO4), zinc sulfide (ZnS) according to the XRD analysis.

Investigation of thermal decomposition of jarosite tailing waste

During the zinc production process from sulfidic ores, the jarosite residue is produced within the precipitate containing ammonia, iron, zinc and other metal sulfates. The process yield jarosite which has been dumped as a waste despite its acidity presents environmental hazard while high content of iron, zinc, lead, cadmium and other heavy metal compounds additionally presents further utilization possibilities. In this paper, the thermal decomposition of jarosite tailing waste collected in Mitrovica Industrial Park situated in Kosovo is investigated in order to get better understanding of its possible utilization as a source of valuable raw materials. Samples of jarosite tailing waste were taken at depths of 0.2, 1 and 2 m. The samples were characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectrometer (SEM/EDS), thermogravimetric analysis (TG) and differential thermal analysis (DTA). The results obtained from XRD confirmed the presence of ammonium jarosite in the investigated tailing waste samples. Results of TG–DTA indicated that the decomposition of jarosite samples occurs in four consecutive stages up to the temperature of 500 °C. On behalf of SEM/EDS analysis, jarosite samples yield poorly defined micron-sized morphology associated with high content of Fe and S, but also Pb, Cd, Zn and As. Composition of jarosite tailing waste was found depth dependent which should facilitate jarosite waste reuse at the investigated site.

On the Development of a Zinc Vapor Condensation Process for the Solar Carbothermal Reduction of Zinc Oxide

In the conventional Imperial Smelting Process, the dominating pyrometallurgical zinc production process, zinc vapor is recovered from the furnace off-gas by absorption into an intense spray of molten lead droplets in a splash condenser, followed by separation of zinc from the Zn-Pb alloy upon cooling from 550°C to 450°C by taking advantage of the decrease in the solubility of zinc in lead at lower temperatures. The adaptation of this condenser technology into a solar-driven thermochemical plant using concentrated solar energy faces several drawbacks owing to its mechanical complications and the continuous recirculation of large quantities of lead. An alternative zinc condenser concept involving gas bubbling through a zinc liquid bath of the off-gas evolved from the carbothermal reduction of ZnO is thus proposed and numerically modeled for transient heat and mass transfer. Condensation of bubbles containing 53.5% of noncondensable gases yielded chemical conversions of Zn(g) to Zn(l) in the range of 95.6–99.8% for operation in the temperature range 500–650°C while conversions of Zn(g) to ZnO in the order of 10−6 were obtained, thus predicting successful suppression of Zn(g) reoxidation by CO2 and CO.

Analysis of steel production in Thailand: Environmental impacts and solutions

Steels were the upstream of various products. The environmental performance of steel can affect those of the downstream products. In this work, environmental impacts of individual steels, i.e. slab, hot-rolled, cold-rolled, hot-dipped galvanized, and electro-galvanized steels, were studied, via life cycle assessment. The impact assessment methods of IPCC 2007 GWP 100a and Eco-indicator 99 (H) were used to cover the impact categories of Global warming potential, Fossil fuels, Ecotoxicity, Minerals, Carcinogens, and Respiratory inorganics. In all categories, the slab showed the lowest impacts and the hot-dipped galvanized steel showed the highest impacts. The main causes of the impacts were attributed to these inputs; steel, energy, and zinc. The emissions from steel production plants showed relatively low impacts. Small amount of zinc input can cause huge environmental impacts. The impacts of Fossil fuels, Minerals, and Ecotoxicity, of 1-kg zinc were 2.9, 116.9, and 39.6 times of those caused by 1-kg cold-rolled steel, respectively. The reduction of zinc consumption and the improvement of zinc production process, in terms of reduction of heavy metal emissions, could largely improve environmental performance of the galvanized steels.

Peroxidase, phenolics, and antioxidative capacity of common mullein (Verbascum thapsus L.) grown in a zinc excess

Common mullein (Verbascum thapsus L.) is the dominant plant species at a disposal site polluted with metal from the hydrometallurgical jarosite zinc production process. Seeds collected at the site were germinated and plants were grown hydroponically under controlled conditions in a excess of Zn. Induction of total soluble POD activity in the root occurred at 1, 5, and 10 mM Zn, indicating Zn accumulation within the root. Accumulation of Zn in leaves was not accompanied by changes in POD activity, but resulted in gradual increase of total antioxidative capacity, which could be partly attributed to accumulation of soluble phenolics. The role of the phenolics/POD system in defense of V. thapsus against zinc is discussed.

Conversion of zinc chloride to zinc sulphate by electrodialysis—a new concept for solving the chloride ion problem in zinc hydrometallurgy

The results presented in this paper describe the course and conditions of electrodialytic conversion of zinc chloride to zinc sulphate using mono- and bipolar ion exchange membranes. The object of this work was to find if such a process can be applied to produce zinc sulphate solutions with low concentrations of chloride ions from solutions of zinc sulphate–zinc chloride obtained from raw materials containing high concentration of chloride. As a result of this work, the influence of the technological parameters on the effectiveness of the process has been determined. The parameters studied include the chemical composition of the working solutions over a wide range of concentrations of individual constituents, the current load of the electrodialytic apparatus, the linear flow velocity of the solution feed, as well as the character of membranes applied in the apparatus. Empirical equations describing the current efficiency of the process, the increase in concentration of chloride ions in the sulphate solution and the selectivity coefficient of the process have been devised, as a function of four independent variables: the current load of the electrodialytic apparatus, the concentration of zinc as zinc sulphate and zinc chloride in the inlet sulphate–chloride solution and the initial concentration of zinc in the sulphate solution, based on the results of complete factorial experimental technique. Analysing the empirical equations has shown that a one-stage electrodialysis process may be applied to produce zinc sulphate solution, with a low enough concentration of chloride ion to meet the requirements of the electrolytic zinc production process, from solutions obtained by leaching zinc-bearing raw materials containing up to 1% concentration of chloride with sulphuric acid.

調合亜鉛製造工程の改善

調合亜鉛製造工程の改善