Zinc Production Research Articles

Life cycle impact assessment of metal production industries in Australia

Metal production industries are associated with positive economic benefits, however their activities are significantly resource and energy intensive, contributing to emission of pollutants and greenhouse gases to the environment. The balance between the economic inputs and environmental footprint of the metal production industries determines their contribution to sustainability. This work provides environmental impact assessment of the production of aluminium, copper, gold, iron and steel, lead, nickel and zinc, and considers their contribution to the economy. The emissions of selected representative industries in Australia were sourced from public national emission inventories and used as input parameters in the openLCA software. ReCiPe midpoint and endpoint hierarchist impact assessment methods were used to investigate the environmental impacts of the selected industries. The results indicate that lead, followed by aluminium and nickel production had the largest environmental impacts. The work further revealed the specific emissions for better control for each industry taking into consideration their relative environmental and economic impacts. For instance, adoption of renewable energy sources would significantly decrease the greenhouse gas emissions and the associated environmental impacts of the copper, zinc, gold, and iron and steel production industries. Improvement of sustainability of the production of lead would require further control of trace metal emissions, while for aluminium and nickel production, improved control of emissions of particles and the acidic gases SO2 and NOx.

Research progress in anodes for zinc electrowinning

Traditional lead anodes are widely used in production of zinc by electrowinning due to their low cost, good conductivity and easy processing. However, the corrosion of lead anodes during the electrolytic process has also lead to the pollution of zinc products and electrolyte and increase of anode use costs. Improving the electrochemical activity and corrosion resistance of the anodes has become one of the important research directions of zinc electrowinning technology. In recent years, based on the corrosion-resistant mechanism in zinc electrowinning processes, a variety of corrosion-resistant anodes with excellent electrochemical performance have been developed, including lead alloy, PbO2, and transition metal oxide coated anodes. This article reviews the research progress of zinc electrowinning anodes such as lead alloy, PbO2 and transition metal oxide coated anodes, and give a prospect of their future development.

Purification of Zinc Oxide from Chlorides Using Microwave Radiation

Waelz oxide is a secondary zinc raw material and a product of Electric Arc Furnaces (EAF) dust, copper smelters dust and zinc production residues. The use of Waelz oxide in the traditional RLE (Roasting-Leaching-Electrowinning) zinc production scheme requires the removal of halogens (fluorides and chlorides). Waelz oxide is mainly composed of zinc oxide, also contains zinc chloride. Zinc chloride is removed into the gas phase at heating. Microwave heating is one of the promising methods. Test experiments of microwave heating of a ZnO-ZnCl2 mixture were carried out. It was shown that zinc chloride absorbs microwave radiation; zinc oxide does not absorb microwave radiation. The degree of zinc chloride removal from ZnO-ZnCl2 mixture was 100%.

The Study of the Melting of Waelz Oxide with an Increase in the Temperature of the Calcination Process

Waelz-oxide is a raw material for the production of metallic zinc. Waelz-oxide contains impurities of zinc and lead chlorides and fluorides. Halides have a negative effect on the process of zinc electrolysis. Halides have a relatively low boiling point; therefore, they are removed into the gas phase by calcining Waelz-oxide at 800–850 °С. To intensify the process, calcination is sometimes carried out at elevated temperatures of 1100–1250 °С. However, an increase in temperature leads to partial melting and granulation of the calcined product. In the present work, the chemical and phase composition of the initial and calcined Waelz-oxide was studied. Thermodynamic modeling of phase and chemical transformations of Waelz-oxide components during heating has been performed. Experiments on calcination of Waelz-oxide in laboratory conditions at temperatures of 600–1250 °C were carried out. It was found that partial melting and granulation of Waelz-oxide is the result of the formation of fusible eutectics containing lead oxide. Lead oxide is formed as a result of decomposition of lead sulfate when heated above 1100 °C. A similar effect is not observed at a standard calcination temperature of 850 °C.

Factors affecting multiple persistent organic pollutant concentrations in the air above Japan: A panel data analysis

Numerous reports have elucidated different statistical approaches to identify temporal trends in atmospheric persistent organic pollutant (POP) time series. However, the correlation of industrial activity with concentrations of atmospheric POPs in Japan has not yet been determined. Herein, a panel data analysis of a 16-year monitoring program (2003–2018) conducted by the Japanese Ministry of Environment was used to investigate a range of POPs in the atmosphere above Japan. This work focuses on polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB), and pentachlorobenzene (PeCBz) collected each year at 53 sites across Japan. The panel analysis revealed that PCB, PCN, and PBDE concentrations were influenced by a combination of factors including year, industrial activity (municipal and industrial waste incinerators, cement kilns, steel industry, and secondary zinc production), population, temperature, and atmospheric boundary layer. However, HCB and PeCBz were not significantly affected by these factors. Industrial activity showed stronger positive correlations with all homologues of PCBs, PCNs, and PBDEs as compared to those demonstrated by population. Significant decreasing trends were identified for the atmospheric ∑PBDEs (half-life t1/2 = 9.4 years), ∑PCNs (t1/2 = 8.9 years), and ∑PCBs (t1/2 = 13.5 years) concentrations, while HCB and PeCBz showed slightly increasing or steady levels. As a statistical tool, panel data analysis can contribute to the assessment of spatial and temporal trends of POPs at a national scale, while elucidating different behavioral responses to numerous environmental variables.

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.

Production of Zinc and Copper as Nanoparticles by Green Synthesis Using Pseudomonas fluorescens.

<b>Background and Objective:</b> Nanoparticles with a little size to an enormous surface (1-100 nm) have expected clinical, mechanical and agricultural applications. This study aimed to produce nano Zinc Oxide (ZnO) and nano Copper Oxide (CuO) particles by green synthesis. <b>Materials and Methods:</b> Two strains of <i>Pseudomonas fluorescens</i> i.e., PSI and PSII, both cell culture supernatants and cell pellets from the two strains were examined separately in CuSO<sub>4</sub> or ZnSO<sub>4</sub> solutions. The supernatants from both strains produced color changes in both solutions referring to the formation of nano CuO or ZnO particles. The solutions were examined for nano-particle characteristics using UV-spectroscopy, particle size and morphology were tested using a scanning electron microscope and transmission electron microscopy. <b>Results:</b> UV-Vis absorption spectrum of solutions at a wavelength range 200-800 nm exhibits a distinct absorption peak in the region of 238-331 and at 303-366 nm for CuO or ZnO NPs, respectively. Absorption bands and the characteristic Surface Plasmon Resonance (SPR) spectra confirm the existence of CuO and ZnO NPs. SEM analysis micrographs indicated that CuO NPs were formed as spherical particles, while the exact shape of ZnO NPs could be identified as oval aggregates. <b>Conclusion:</b> Changes of color occurred in both solutions of two strains referring to the formation of nano CuO or ZnO particles.

Studies of Soils and Vegetation on Non-ferrous Metallurgy Slag Dumps

The metallurgical industry is one of the major pollution sources of natural ecosystems. Now the slag dumps of non-ferrous industries occupy huge areas all over the world. The purpose of this literature review was to assess the knowledge degree of the soils and vegetation formed on the non-ferrous metallurgy slag dumps. Most of the research was carried out for the dumps of the copper-smelting (including old dumps) and lead-zinc industries, the dumps of the nickel and aluminum industries have been studied to a lesser extent. The composition of non-ferrous metallurgy slags, the issues of soil pollution with heavy metals, their bioavailability were discussed. The influence of heavy pollution on the biodiversity of pioneer plant communities on the slag dumps of non-ferrous metallurgy and the floristic composition for abandoned copper ore deposits are noted. The experience of Russian scientists in the reclamation of an aluminum sludge dump and Chinese scientists in the reclamation of zinc production slag dumps are considered. The possibility of introducing waste from the copper smelting slag recycling waste into natural ecosystems was discussed. The analysis of literature revealed gaps in knowledge about the gradual formation of the soil and vegetation on man-made landscapes, about the plant biodiversity in conditions of heavy pollution, ways of their adaptation, and the heavy metals accumulation by different plant species.

Hydrometallurgical extraction of antimony from lead refining slags

Today, in order to optimize the production of copper, zinc, and lead, as well as to reduce the circulation of associated metal impurities (such as antimony, tin, bismuth and others) between the processing facilities, an ever greater attention is given to the development and implementation of processing schemes that would enable to extract associated metals and use them to produce commodities. In connection with the above, a process has been developed and tested for processing lead refining slags which include, %: 25–30 Sb, 2–10 Pb, 1–8 Sn, 3–12 As, 0.1–0.2 Cu. The resultant products included the Su-2, Su-1 and Su-0 grades of antimony or antimonous oxide. It was found that the forms in which antimony was present in the untreated slag included Sb2O3, Sb2O4, Sb2O5 and NaSb(OH)6. A hydrometallurgical process based on the use of sulphide alkaline solutions was taken as the basic slag processing technique. It is proposed to wash the slag additionally before leaching to remove arsenic from antimony, and to use the electrowinning stage to separate tin from antimony. Regimes have been identified for obtaining cathode deposits containing 96–99% Sb, with the recovery of antimony from untreated slag being 67%. The cathode deposits were refined with the help of pyrometallurgical methods and electrolysis in sulphate-fluoride media. The paper also considers the possibility of obtaining antimonous oxide by oxidizing the antimonous oxide melt and recovering Sb2O3 from exhaust gases. Based on the findings and the results of the tests, Uralelectromed is now working on designing a slag processing facility.

Properties of calcium aluminate blended cement incorporating iron-rich slag: Evolution over a curing period of 1 year

With an outlook directed towards circular economy, the valorization of municipal waste streams and industrial residues has recently conveyed a variety of novel industrial by-products to various applications such as supplementary cementitious materials (SCM) in cement blends or as precursors to inorganic polymers. Despite the synergistic benefits on recycling, reducing the cost and the carbon footprint of cements, the use of such non-conventional SCM is often limited to ordinary Portland cement (OPC)-based formulations. This study investigates the properties of a calcium aluminate cement (CAC)-based blend incorporating 30 wt% of iron (Fe)-rich slag produced at pilot scale from an industrial lead–zinc production. Compressive and flexural strength (EN 196-1 standard mortars), setting time, dimensional stability (Walter + Bai shrinkage measuring test), early hydration reactions (isothermal calorimetry), and phase assemblage evolution (XRD and TGA) were followed from 1 day to 1 year of curing period for both the slag-containing- and a corresponding reference cement formulation. Additionally, a fast non-destructive technique for quantifying the degree of slag hydration is demonstrated using a combination of X-ray computed tomography (XCT) and volume analysis based on grayscale threshold segmentation. The results from the different techniques suggest the long term (>28 days) reactivity of the slag with the slag-containing mortars attaining a comparable compressive strength of 39 MPa versus 41 MPa of the corresponding reference mortars at 90 days. Likewise, the prominent contribution of the slag to the hydration reactions is manifested by the differences in the evolution of the phase assemblage of the two formulations. The degree of slag hydration was calculated to progressively increase over time reaching up to 49% after 1 year of hydration based on the XCT scans. These results along with the long term dimensional stability of the slag-containing formulation support the potential for valorization of the Fe-rich slag as SCM in the CAC-based blend.

Cladosporium sp. Isolate as Fungal Plant Growth Promoting Agent

Cladosporium species are active in protecting plants against different biotic and abiotic stresses. Since these species produced a wide range of secondary metabolites responsible for the adaptation to new habitats, plant health and performance, they are of great interest, especially for biostimulants in agriculture. Cladosporium sp. produces protein hydrolysates (PHs), a class of biostimulants, by cultivation on medium with keratin wastes (feathers) as carbon and energy sources. The aim of this study was to select a Cladosporium isolate with potential to be used as plant growth promoting agent. The characteristics of Cladosporium isolates as plants biostimulants were evaluated through several tests, such as: antagonism versus plants pathogens, effect on plant growth of secreted volatiles produced by isolates, secretion of hydrolytic enzymes, production of 3-indole acetic acid, zinc and phosphorous solubilization, capacity to promote tomato seedlings growth (pot experiments). Cladosporium isolate T2 presented positive results to all tests. Encouraging results were obtained treating tomato seedlings with PHs from isolate Cladosporium T2 cultured on medium supplemented with 1% (w/w) chicken feathers, for which growth parameters, such as stem weight, stem height, and root weight were significantly higher by 65%, 32%, and 55%, respectively, compared to those treated with water.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ТЯЖЕЛЫХ МЕТАЛЛОВ НА ПОЧВЕННЫЙ ПОКРОВ И МЕТОДЫ ИХ БИОРЕМЕДИАЦИОННОГО КОНТРОЛЯ

The article provides information on literature and patent information on the analysis of heavy metals formed during the extraction and processing of various types of raw materials for the production of non-ferrous metals and chemical products. The influence of heavy metals on the environment and living organisms, fauna and flora, as well as people living in different industrial regions of Kazakhstan is shown. Migration of heavy metals in the soil cover hydrosphere and atmosphere is shown. Based on the analytical review, the goals and objectives of the study are outlined, the chemical composition of raw materials for the main heavy metals formed in solid and dust - like production waste, and for technological processing in the production of lead and zinc in the East Kazakhstan and Turkestan regions is shown. Information is provided on the presence of heavy metals in the soil and their purification by various bioremediation methods. The data of soil analysis on the territory of the Turkestan region in recreation areas of people and in non-ferrous metallurgy enterprises nearby to the mining complex are presented. The dependence of the distribution of heavy metals and the chemical composition of the analyzed samples taken in various points of the Turkestan region and the city of Shymkent is shown. Data on the maximum content of heavy metals in the soil at which experimental worms die are established.

<p class="Body"><strong>Injurious status of <em>Schizotetranychus schizopus </em>(Zacher, 1913) (Acari: Tetranychidae) on Indian Thorny Bamboo</strong></p>

Spider mites, especially members of Schizotetranychus represent a common and dominant group of bamboo pests, enjoying worldwide distribution. The present paper highlights the feeding attributes of a notorious species of bamboo spider mite, viz. Schizotetranychus schizopus (Zacher, 1913) infesting the Indian Thorny Bamboo, Bambusa bambos (L.) Voss. Observations on feeding behavior of the mite were completed in the laboratory by collecting mite specimens from infested leaves of bamboo plants grown in Calicut University Botanical Garden. The species showed initial colonization on the abaxial surface of bamboo leaves, adjacent to the midrib and feeding activity of the members of the colony resulted in the development of damage symptoms like chlorotic spots, white patches, yellowing etc. Comparative analysis of the biochemical constituents of mite infested and uninfested leaves of B. bambos revealed significant alterations. Mite infested bamboo leaves presented significantly reduced values of chlorophyll fluorescence (30.10% loss in Fv/Fm ratio) thereby indicating a decline of photosynthetic efficiency. Significant reduction in total carbohydrate (58.87%) and total protein (21.02%) contents also could be accounted in mite infested leaves. Meanwhile, mite infestation was found to enhance the production of stress compounds such as Total Phenol (22.86%) and Proline (69.05%). An increase in the uptake of micro and macronutrients like Potassium (18.87%), Calcium (36.66%), Copper (48.76%) and Zinc (19.62%) was also observed in mite infested leaves. Despite this, the uptake of nutrients such as Phosphorus (8.22%), Magnesium (3.55%), Sulphur (1.54%), Iron (11.46%), Manganese (13.64%) and Boron (30.09%) significantly decreased owing to mite infestation. Significant decrease in moisture content also was evident in the mite infested bamboo leaves. The results of the study helped to evidence the biotic stress induced by the mite on its bamboo host, by promoting enhanced production of Total Phenol, Proline, Potassium, Calcium, Copper and Zinc which would play a substantial role in the defense mechanism of the plant.

Carbon footprint of the hot-dip galvanisation process using a life cycle assessment approach

This work presents the carbon footprint (CF) of two hot-dip galvanisation (HDG) installations located in Spain with differences in the galvanising capacity and in the manufacturing process. The study determines the influence of the direct emissions (scope 1), emissions from electricity production (scope 2), and indirect emissions from upstream and downstream processes (scope 3). The results showed that steel and primary zinc production were the principal contributors to the CF. So, efforts should be focused on reducing the impact of the raw material production included in scope 3. Furthermore, two sensitivity analyses are presented: i) the production of one kg of two types of zinc products, special high-grade and redistilled zinc; ii) the use of two coatings: zinc for galvanisation and paint for pre-printed steel. The environmental impacts in SHG zinc were higher than in redistilled zinc, for all the impact categories due to the great influence of heavy metals emission. The results for zinc and paint protections showed that under the same level of corrosion, a greater thickness of paint is needed to protect steel pieces, compared to zinc coating. This sustainability assessment of the HDG industry recommends the sought of technology alternatives aimed at resource efficiency, such as zinc recovery from spent pickling baths, that could provide the desirable reduction of the environmental impacts associated to primary resource usage and waste treatment.

Material flow analysis of zinc during the manufacturing process in integrated steel mills in China

The steel manufacturing process involves not only the substance flow of iron from iron‐bearing materials to steel products but also the circulation and movement of many additional elements. In this study, the flow and circulation of zinc during coking, sintering, blast furnace (BF) ironmaking, basic oxygen furnace (BOF) steelmaking, and continuous casting processes, which has been neglected, was analyzed in an integrated iron and steel mill throughout 2013. The results indicated that approximately 2,317 tonnes (t) of zinc from steelmaking raw materials were input into the studied steel mill in 2013, of which 58.8% originated from iron ore fines, 22.3% from pellets, and 8.8% from lumps. Although 1,212 t of zinc was discharged along with coking chemical products and steel slag after magnetic separation or iron‐bearing dust and sludge, 1,105 t of zinc remained within the circulation. According to this research, we inferred that approximately 142 kilotonnes of zinc, 2.7% of China's zinc production in 2013, and approximately 1.5 million tonnes in total from 2000 to 2017 were concentrated in BF and BOF dust or sludge. This large amount of zinc has been ignored by Chinese steelmakers and zinc producers, although it should be used as a resource for zinc recycling. Thus, integrated steel mills should develop pertinent treatments targeting these fractions to prevent and handle the hazards from the circulation and concentration of zinc inside their premises.

Reductive leaching of indium from zinc-leached residue using galena as reductant

Large quantities of indium-bearing zinc-leached residue (ZLR) are produced constantly in the hydrometallurgical production of zinc, including zinc, indium, iron and other valuable metals. In order to recover valuable metals from the residue, a new reductive leaching process using galena as reductant has been developed, in which the extensive leaching of zinc and indium is achieved. A shrinking core model under the control of surface chemical reaction best fitted the leaching of indium from the residue. The apparent activation energy of indium leaching was calculated to be 64 kJ/mol, and the reaction orders were determined as −0.34 and 1.47 with respect to particle size and initial H2SO4 concentration, respectively. The extent of leaching was 87% for zinc, 91% for iron and 88% for indium after 90 min at 85 °C, using an initial H2SO4 concentration of 140 g/L and a molar ratio of lead sulfide to zinc ferrite of 1:1. The reductive leaching process of the residue achieved high dissolution of zinc and indium, and iron existed as Fe2+ in solution would prove beneficial for the subsequent iron removal stage.

Comparative Life Cycle Impact Assessment between the Productions of Zinc from Conventional Concentrates versus Waelz Oxides Obtained from Slags

(1) Background: The importance of Zinc in today’s world can hardly be exaggerated—from anticorrosion properties, to its durability, aesthetic, and even medicinal uses—zinc is ever-present in our daily lives ever since its discovery in ancient times. The natural, essential, durable, and recyclable features of zinc make it a prized material with uses in many applications across a wide array of fields. The purpose of this study was to compare two life cycle impact assessments of zinc production by using two different main raw materials: (A) zinc concentrates (sulfide ore) and (B) Waelz oxides (obtained through recycling existing imperial smelting process furnace slags). The Waelz oxide scenario was based on a case study regarding the existing slag deposit located in Copsa Mica town, Sibiu county, Romania. (2) Methods: consequential life cycle impact assessment methods were applied to each built system, with real process data obtained from the case study enterprise. (3) Results: Overall, the use of slags in the Waelz kiln to produce zinc oxides for use in the production of zinc metal is beneficial to the environment in some areas (acidification, water, and terrestrial eutrophication), whereas in other areas it has a slightly larger impact (climate change, photochemical ozone formation, and ozone depletion). (4) Conclusions: The use of slags (considered a waste) is encouraged to produce zinc metal, where available. The results are not absolute, suggesting the further need for fine-tuning the input data and other process parameters.

Study on recovery of copper and zinc from cyanide lean solution in a smelting company

In the process of cyanidation of gold concentrate from a smelting company, the content of copper and zinc in the liquid gradually increased. In production, acidizing process is used to treat the lean solution from high copper concentrate, and mixed products containing copper, zinc and other metals are produced. In this paper, the pH value of zinc precipitation is 6.0 and the pH value of copper precipitation is 3.0 through theoretical calculation and experiment. The separation of copper and zinc in the lean solution is realized successfully. The zinc product with grade of 42.97% and the copper product with grade of 58.33% are produced.

Pedeset godina metalurške proizvodnje cinka i kadmijuma u Srbiji

Serbia has plenty of rich sites and active excavation mines of polymetallic ores of lead and zinc and centuries-old practice of their exploitation. In Serbia, the metallurgical processing of zinc concentrate started in 1955 at Zorka company in Šabac, while in the town of Kosovska Mitrovica, it began in 1967 at the Trepča combine. Several factors, including the fall o Yugoslaviam general societal circumstances and ownership transition, lead to a significant decline in production since 1992. It developed to the final halt of zinc's metallurgical production in 1999 at Trepča and in 2002 at Zorka. During the work-life o both production sites, since they opened till they closed, there were several reconstructions and capacity expansions, and all the while, the normalization and renewal of zinc production in Serbia hasn't been realized till 2021.

Lead release kinetics and film transformation of Pb-MnO2 pre-coated anode in long-term zinc electrowinning

Lead pollution precaution caused by lead-based anode corrosion is a hot and challenging issue for zinc electrowinning. A novel functional lead-based anode (MnO2 pre-coated anode-MPA) was precisely fabricated and its long-term performances were studied compared with typical Pb−1%Ag anode (TPA). Results indicated that MPA posed excellent effects on synergistic inhibiting lead dissolution and reducing hazardous pollutants generation, and decreasing the lead content of zinc products by 81%. Further, the underlying mechanism of film growth and transformation in structure, composition and crystal phase, the migration and distribution of lead and anode slime during electrolytic, were clarified in-depth. Dynamic material flow analysis confirmed that MPA reduced the entire lead migration amount by over 92% compared with TPA. The compact multilayer structure of the MPA film and self-reparation effects of local structure provided better and persistent protection for the lead matrix, which greatly retarded the high-speed corrosion of lead anode. Compared with α-MnO2 in TPA, the formation and maintenance of γ-MnO2 in MPA accelerated the oxygen evolution reaction and inhibited the anode slime generation. This finding provides new insights in pollution precaution and control by designing and tuning new functional anode in hydrometallurgy process.