Zinc Industry Research Articles

Lead-silver anode behavior for zinc electrowinning in sulfuric acid solution

Abstract In recent years, a renewed interest in studying the electrochemical corrosion behavior of lead anodes during zinc electrowinning is probably due to the particularly high sulfuric acid concentrations in zinc electrolyte where lead alloy anodes have high cell voltage and high corrosion rate of lead. The high corrosion rate of lead alloy resulted in Pb contamination on zinc deposit. In zinc electrometallurgy, the electrolyte from a zinc-rich ore contains a significant amount of Mn2+. Mn2+ in the zinc electrolyte results in forming an oxide film on lead anodes during electrolysis. Pb-0.7% Ag anode is generally used in the zinc industry. To improve the technical performance and decrease product cost, other anodes, such as Pb-Ca or Pb-Ag-Ca or Pb-Ag-Ti or Pb-Ag-Se alloys were tested. Till now, none of them has succeeded in the substitution of Pb-Ag anodes in the zinc electrowinning. As an alloying element, silver in small quantities is considered because of the benefits that generates on the anode during electrolysis. During zinc electrolysis, lead dissolution into the zinc electrolyte can be harmful to the quality of zinc deposit. However, the lead silver alloy anode can decrease the lead content in the zinc deposit by pre-treated methods such as blasting and preconditioning.

Methanesulfonic acid: a sustainable acidic solvent for recovering metals from the jarosite residue of the zinc industry

Leaching the industrial jarosite residue with pure methanesulfonic acid resulted in a solid–liquid separation of iron from dissolved lead and zinc by precipitation.

Recovery of Hg from mercury sludge enhanced by oxidizing roasting in a microwave field

The management of residues from the metallurgical industry is an integral part of waste management. Mercury sludge is a by-product of the acid-making step and has a high content of Hg in the form of HgS and HgO. With the development of zinc industry, proper utilization of the high-risk mercury sludge has drawn great attention. In this paper, a new technology for recovery of Hg from mercury sludge enhanced by NaClO addition and microwave heating is proposed. By adopting various analysis techniques, effect of NaClO addition and microwave-assisted drying in the pre-treatment process are demonstrated. Results showed that microwave-assisted drying can increase the oxidation of mercury sludge, and NaClO can react with HgS to produce HgO and Hg, two volatile materials. The pre-treatment effect is optimum when mixing ratio of NaClO to mercury sludge is 1:2. Moreover, upon roasting this sample in microwave equipment at 450 °C for 20 min, Hg recovery can reach 92.31%.

Characterisation of jarofix for use in geotechnical projects

A detailed laboratory study was carried out to evaluate the physical, chemical and geotechnical characteristics of jarofix (a waste material generated by the zinc industry) before assessing its applicability for embankment construction. Mineralogical and morphological properties, shape, crystallinity and the concentration of inorganic and heavy metals were evaluated. The stress–displacement behaviour of jarofix was studied by conducting a series of direct shear tests at different normal stresses and dry densities. The parameters studied were the shear stress, shear stress ratio, horizontal and vertical displacements, peak and critical friction angles and dilation. These parameters were compared with those of other suitable embankment materials. It was found that jarofix has a polycrystalline structure with cuboidal particles and a non-hazardous nature. The peak shear stress values at higher density were significantly higher than those at lower density. The stress–strain and volume-change behaviour of the jarofix was found to be similar to those of silty soil, fly ash, sandy soil and dense sand. It is concluded that jarofix can be utilised as an alternative embankment material for sustainable road construction.

Preparation of ZnFe2O4/α-Fe2O3 Nanocomposites From Sulfuric Acid Leaching Liquor of Jarosite Residue and Their Application in Lithium-Ion Batteries.

Recycling Zn and Fe from jarosite residue to produce high value-added products is of great importance to the healthy and sustainable development of zinc industry. In this work, we reported the preparation of ZnFe2O4/α-Fe2O3 nanocomposites from the leaching liquor of jarosite residue by a facile chemical coprecipitation method followed by heat treatment at 800°C in air. The microstructure of the as-prepared ZnFe2O4/α-Fe2O3 nanocomposites were characterized by X-ray diffraction (XRD), Mössbauer spectroscopy, scanning transmission electron microscope (STEM), and X-ray photoelectron spectrum (XPS). The results demonstrated that the ZnFe2O4/α-Fe2O3 composites are composed of interconnected ZnFe2O4 and α-Fe2O3 nanocrystals with sizes in the range of 20–40 nm. When evaluated as anode material for Li-ion batteries, the ZnFe2O4/α-Fe2O3 nanocomposites exhibits high lithium storage activity, superior cyclic stability, and good high rate capability. Cyclic voltammetry analysis reveals that surface pseudocapacitive lithium storage has a significant contribution to the total stored charge of the ZnFe2O4/α-Fe2O3, which accounts for the enhanced lithium storage performance during cycling. The synthesis of ZnFe2O4/α-Fe2O3 nanocomposites from the leaching liquor of jarosite residue and its successful application in lithium-ion batteries open up new avenues in the fields of healthy and sustainable development of industries.

Significantly enhanced dehalogenation selectivity in near-neutral zinc sulfate electrolytes by diffusion dialysis

For industries around the world, the hydrometallurgical roast–leach–electrowin process is the most common means of producing zinc metal. Dechlorination from the highly-concentrated zinc sulfate electrolyte is of vital importance to the zinc industry. In a recently published work, we innovatively employed diffusion dialysis (DD) to selectively remove Cl- and F- from a highly-acidic spent electrolyte, which extended the application of DD from acid recovery to selective ion separation. In the current paper, we greatly enhance the dechlorination selectivity by adjusting the acidity of feed electrolytes. The Cl-/SO42- permselectivity increases from 2.56 to 42.8 when the acidity is reduced from 160 to 0 g/L as free H2SO4, and meanwhile the removal ratio of Cl- impurity is basically retained (from 55.1% to 46.6%). The competitive permeation of different ions and the interplay between anions and cations are carefully investigated. It is believed that the distinct diffusivity of anions (Cl-, F-, HSO4- and SO42-) originates from their different hydrated sizes. This excellent selectivity observed here is unprecedented and has never been observed in any practical DD processes. It not only remarkably improves the cost-effectiveness of the dechlorination process in zinc production, but also puts forward a new possibility to regulate the permselectivities between ions with the same charge sign and provides new insights into the DD process in the selective ion separation.

Production of low-sulfur hematite by hydrothermal oxydrolysis of ferrous sulfate

Hematite produced by the zinc industry exhibits a high sulfur content, being mainly contaminated by jarosite as the main sulfur-containing phase, and is thus of limited use for the steelmaking industry. Herein, we investigate the effects of parameters such as temperature (170–200 °C) and initial concentrations of sulfuric acid (0–19.6 g/L), sodium sulfate (0–35.5 g/L), hematite seeds (0–30 g/L), and Zn2+ (80–120 g/L) on the formation and conversion of jarosite during hematite precipitation from a ferrous sulfate solution, obtaining high-quality hematite with a low sulfur content.We reveal that increased temperature not only benefits jarosite conversion but also reduces the sulfur content of precipitates and enriches them in iron. Sulfuric acid concentrations of 4.9–19.6 g/L greatly decrease the fraction of precipitated iron and produce sulfur-rich precipitates containing significant amounts of both hematite and jarosite, whereas sodium sulfate increases the iron removal efficiency and the sodium content in hematite precipitates. Hematite seeds prompt the precipitation of hematite and affect the composition of the obtained precipitates, promoting the precipitation of hematite in preference to jarosite at relatively low temperatures. Finally, zinc sulfate concentrations of 80–120 g/L have a positive effect on iron removal as hematite.

Assessing the policy impacts on non-ferrous metals industry's CO2 reduction: Evidence from China

Abstract The nonferrous metals industry (NMI) consumes a great amount of energy, and is a typical high CO2 emission sector. The NMI is one of the eight most concerning industries in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report. In this study, we summarized policies that impact Chinese NMI's development and grouped them into three types: energy structure policies, energy efficiency improving policies and production-scale policies. Based on those quantitative policy goals, a bottom-up model has been developed to study the CO2 emissions of five NMI's major sub-sectors from 2010 to 2030. The results showed that if China's central government could stick to the CO2 reduction policy strength of 13th Five-Year Plan (2016–2020), then the copper, lead and zinc industries can reach their emissions peak before 2030. Furthermore, if the Chinese government restricts the production of primary aluminum of 46.2 million tons in 2025, then the CO2 emissions of China's non-ferrous industry could reach the peak in that year, when the CO2 emissions peak is 297 million tons. Having benefited from the effective CO2 reduction policies of NMI, China may reach its ambitious CO2 peaking goals more easily.

Development of Waelz-Oxide Hydrometallurgical Processing Technology with Preparation of Carbonized Lead Cake

Comprehensive processing of ore and technogenic raw material containing zinc and lead requires improvement of lead-containing product quality provided by zinc industry enterprises for lead extraction by a pyrometallurgical method. Research and development are conducted for Waelz-oxide pyrometallurgical treatment technology with preparation of carbonized lead cake containing more than 45% lead, not more than 5% sulfur, and with a moisture content after filtration less than 35% suitable for black lead preparation in short-drum kilns with good technical and economic efficiency. Carbonization and pyrometallurgical treatment of carbonized lead cake make it possible to reduce soda consumption and sulfur compound concentration considerably in waste gases. Introduction of contemporary technology for preparing Waelzprocess charges drawing on treatment of copper production zinc- and lead-containing dust, and also optimizing process parameters for cake preparation and carbonizing make it possible to increase the lead content in carbonized cake from 40–43 to 46–50%. In order to resolve the problem of increasing lead content and reducing lead cake moisture content, filtered in filter-presses, research is conducted in the course of which the phase composition of sulfate and carbonized products and thermal effects proceeding during carbonized cake drying and heating are studied. Optimum parameters are determined for introducing the technology on the bases of industrial tests. Washing lead sulfate cake before carbonization makes it possible to increase the lead content by 2–4% in carbonized cake. A reduction in pH during lead cake carbonization from 8.5–9.0 to 7.0–7.5 makes it possible to reduce the filtered product moisture content from 35–36 to 27–30%.

The Impact of Innovative Products in the Metallic Zinc Market Growth in Brazil

ABSTRACT International market movements have been stimulating the recent process of industrialization in Brazil, with an increasing growth in the offer and demand of higher added value products in various sectors and segments. Metallic zinc plays a significant role in the Brazilian exports and in the automotive and building industries as well. Further to the availability of new technologies, the zinc industry in Brazil has been commercializing zinc alloys, perceived as higher added value products, for several applications. This study aims at analyzing how innovation and the zinc alloys may influence the metallic commodities market development in Brazil. It was carried a nationwide survey with a non-probabilistic sample of either employees or owners of companies that use zinc and its alloys. For the answers analysis it was used the Discourse of the Collective Subject, a qualitative and quantitative methodology. Zinc alloys influence positively the metallic zinc market growth, though their high prices were considered as a restriction factor for their use.

Selective removal of halides from spent zinc sulfate electrolyte by diffusion dialysis

Zinc metal is mainly produced by a hydrometallurgical process, in which zinc electrolyte is recirculated, and impurities especially halides are accumulated then, which have dreadful impacts on the process and product. Until now numerous efforts have been made to remove halides from the electrolyte, but none of them are fully satisfying, and it is still a big issue for the industry. As a conventional membrane technology, diffusion dialysis (DD) is originally designed to recover free acid from acid-salt mixture by concentration gradient. In this work, we proposed a novel process to selectively remove these halide impurities from the spent zinc electrolyte by DD directly. Significant Cl- and F- permselectivities over HSO4- are observed in this process. The removal efficiencies are as high as 50–70% and 30–42% for chloride and fluoride, respectively, while the zinc loss is less than 1%. The flow intensity in the current work is much higher than that in conventional DD, which reduces the overall cost immensely. The mechanism of this selective mass transfer is also studied intensively to understand influence of flow intensity, charge number and hydrated radii of ions on the permselectivity. The results here are not confined to provide a superior method to remove halide impurities for the zinc industry, but also extend new applications and deepen understandings for the well-established DD process in selective ion separation. This capability is very likely to become a new growth point and future direction for the DD process besides acid/alkali recovery.

Successful sulfur recovery in low sulfurate compounds obtained from the zinc industry: Evaporation–condensation method

The improvement of an evaporation–condensation method allows for successful recovery of elemental sulfur from sulfide concentrates from the zinc industry. Elemental sulfur can be obtained with this method in samples with a low (60%) sulfur content. The effects of heating temperature between 150°C and 250°C and heating time up to 120min on the recovery of sulfur are also studied. Elemental sulfur obtained in this way is of high purity and therefore, there is no need for further purification. The treatment of these industrial residues would help removing sulfur from the environment.

Assessment of Studying Books as the Original Source of Knowledge Acquisition by the Top-Level Managers in Zinc Industry

Which are the main acquisition resources of formal and informal knowledge for Top-level industrial managers? How are these resources utilized and when are they get used? How are the quality and quantity of these knowledge acquisition resources assessed? This research tries to explore these three questions.

Review of oxide coated catalytic titanium anodes performance for metal electrowinning

Conventional lead alloys are widely used in the zinc industry, in spite of their high overpotential and Pb contamination of the deposit during zinc electrowinning. The Oxide Coated Catalytic Anodes (OCAs) are considered to improve cathodic zinc purity and decrease cell voltage during zinc electrowinning. Considering the Ti substrate and its coatings such as (70%) IrO2+(30%) Ta2O5 coatings, the composites of OCAs have low overpotentials 400–500mV less than Pb-Ag anode. It was found that the oxygen evolution potential of the Ti/(Ir-Co) is 370mV lower than that of the lead alloy anode. Ta2O5 has more electric resistance than cobalt oxide and can lead to higher overpotentials. Also, RuO2 is an excellent electro-catalytic rutile structure. Considering generally a low cost coating of Ti substrate, Ni is more appreciable than that of zinc for the two systems of Co-Ni and Co-Zn coated over titanium. Addition of certain chemicals to the zinc electrolyte can decrease MnO2 deposition on the OCA anodes during zinc electrolysis. Moreover, the performance of OCA anodes increased with the nanoparticles addition of both IrO2 and the Sb-doped SnO2. To improve the service life of Ti substrate, procedures such as recrystallization, annealing treatment and surface anodic treatment could be employed. A conductive carbon-polymer has been developed to replace the titanium substrate, which is composed of graphite fibre, carbon black and polyolefin. Finally, aluminum has been studied for matrix because of its good electrical conductivity and mechanical strength.

Sulfidation Roasting of Hemimorphite with Pyrite for the Enrichment of Zn and Pb

With the increasing consumption of zinc and the depletion of zinc sulfide ores, the exploitation of low-grade zinc oxide ores may be important for the sustainability of the zinc industry. Hemimorphite, a zinc hydroxyl silicate hydrate, is a significant source of Zn and Pb. It is difficult to obtain Zn and Pb from the hemimorphite using traditional technology. In this work, for the first time, sulfidation roasting of hemimorphite with pyrite was studied for the enrichment of Zn and Pb by a flotation process. Four stages of sulfidation roasting were determined based on x-ray diffraction and thermogravimetry analysis. Then, the effects of sulfidation temperature, pyrite dosage and reaction time on the sulfidation percentages were investigated at the laboratory scale. The experimental results showed that the sulfidation percentages of Pb and Zn were as high as 98.08% and 90.55% under optimum conditions, respectively. Finally, a flotation test was performed to enrich Zn and Pb in the sulfidation product. A flotation concentrate with 8.78% Zn and 9.25% Pb was obtained, and the recovery of Zn and Pb reached 56.14% and 75.94%, respectively.

Development of zinc, tin, and lead recovery process from secondary technogenic raw materials

The raw-material base of non-ferrous metal production can be extended now as a result of recycled material and technogenic product processing. For the zinc industry, a special interest can concern polymetallic dusts of the copper production containing a complex of valuable components including zinc, lead, tin, and copper. An actual problem is selective extraction of the metals in the course of industrial processing of dusts. The work describes the copper processing practice now in force at OAO "Chelyabinsk Zinc Works"; the basic technical problems concerned with inhomogeneity of properties of various zinc-containing raw materials are presented. The phase and element compositions of the subject of inquiry – dusts of allowing powder materials – are given. Based on the results of the thermodynamic simulation of the pyrometallurgical copper dust processing practice, the principal reactions promoting the distillation of volatile zinc, lead, and tin compounds at the conditions of high temperatures have been analyzed. The results of kinetic parameter determination for sublimation reactions of the said metals are given. From the results of some laboratory researches, the basic optimum conditions are developed for the maximum transit of zinc, lead, and tin compounds into gas phase at the Waelz process of dusts of the copper production.

Supply Chain Optimization of Zinc Industry: Opportunities, Strategies and Challenges

Purpose: The contemporary manufacturing and manufacturers competitive priorities and leadership serves customers who are demanding customized products with squeezed lead time. Detailed study on supply chain management in Zinc Industry have been limited. The Industry has been active only during the last decade. The supply chain management and logistics management in Zinc Industry had been largely confined to distribution activities i.e. outbound logistics as the part of inbound logistics is limited. The present paper focuses on the framed part, mainly considering zinc refiners and their respective customers i.e. Galvanizers, die casting companies. Such model excluded secondary zinc producers, who generally act independent of other factors and the customers they supply. The concentration of production of non ferrous metal ores raises the important issue of supply vulnerability.

Evaluation of waste slags produced by zinc industry in bituminous hot mixtures

Owing to the large amount of waste slags produced by zinc industry, it has become necessary to recycle it in some areas. Road construction has significant potential for the use of waste materials because more material is always needed. In this study, the engineering behaviour of asphalt concrete was investigated using mineral aggregates with waste slag, which is a by-product of the zinc–lead production industry. The asphalt concrete tested in this study was fabricated using 25, 50, 75 and 100 % mixing ratios instead of the conventional fine mineral aggregate (11, 22, 33 and 44 % rate of total aggregate mixture) to determine the possibility of using slags in the binder course of bituminous hot mixtures. The asphalt concretes, made of waste slags and conventional asphalt concrete, were evaluated in terms of their fundamental engineering properties such as Marshall stability, flow, Marshall quotient (MQ), bulk specific gravity, air voids and voids filled with bitumen in the total mix characteristics. The results indicate that the addition of waste slag as mineral aggregate improves the engineering characteristic performance and that it can be used in bituminous hot mixtures. In addition, principal component analyses were applied to examine the significance of each Marshall parameter, and a regression model was developed to estimate the MQ value using effective parameters.

Mineralising effect of jarosite: a zinc industry by-product in the manufacturing of cement

The presence of mineral phases bearing iron, sulfur, sodium, potassium and zinc in jarosite, a residual by-product of the zinc industry, showed its suitability for use as a mineraliser in the development of clinker mineral phases. Different cement raw mixes RM-1 to RM-5, prepared by incorporating 0·5–1·75 wt% jarosite, maintaining clinker parameters LSF: 0·92, SM: 2·14–2·22, AM: 1·09–1·13, potential phases C3S: 57·73–58·84, C2S: 17·37–17·97, C3A: 5·57–6·00 and C4AF: 14·06–14·42 and fired at temperatures of 1300, 1350, 1400 and 1450°C showed the mineralising effect of jarosite in terms of rapid lime assimilation and improved clinker mineral phase formation as compared to a control mix prepared without using jarosite. The optimum clinkerisation temperature was reduced by ∼50°C. The physical characteristics of the cement sample (OPC-4) prepared with 1·5 wt% optimised dose of jarosite showed a 18–25% increase in compressive strength development at early ages as compared to the control cement. As jarosite contains heavy elements such as barium, cobalt, copper, lead, manganese, strontium, zinc and so on, a leaching study was taken up by immersing 28-d hardened neat cement cubes in aggressive mediums such as sulfate, chloride and alkaline solutions along with lean water over a period of 24 months. The leachates contents were found to be in negligible amounts, indicating fixation of heavy elements in clinker mineral phases.

Highly cadmium tolerant fungi: their tolerance and removal potential.

BackgroundSoil and effluent of lead and zinc industries contain high concentration of cadmium. The present study was conducted to isolate tolerant fungal strains from cadmium -polluted sites in Zanjan province, Iran.MethodsCadmium tolerance and bioremediation capacity of seven isolates including Aspergilus versicolor, Aspergillus fumigatus, Paecilomyces sp.9, Paecilomyces sp.G, Terichoderma sp, Microsporum sp,Cladosporium sp were determined.ResultsMinimum inhibitory concentration values among 1,000-4,000 mg lˉ1proved great ability of isolated strains to survive in cadmium polluted environments. The most tolerant fungi, Aspergilus versicolor, showed tolerance index of 0.8 in 100 mg lˉ1 cadmium agar media. Fungal resistance against cadmium is depended directly on strain’s biological function.A. versicolor was found to bioaccumulate over7 mg of cadmium per 1 g of mycelium, followed by 5.878, 5.243, and 5.075, 4.557 by Paecilomyces sp, Aspergilus fumigatus, Microsporum sp and Terichoderma sp, respectively.ConclusionIt can be noted that tolerance of the strains appears to be independent from bioaccumulation capacity. Finally, the results indicated that A. versicolor could be a prospective candidate for bioremediation processes.