Zinc Calcine Research Articles

Selective Lead Extraction from Zinc Calcine and Zinc Leaching Residue by Leaching with Monoethanolamine Solvent Systems

Selective Lead Extraction from Zinc Calcine and Zinc Leaching Residue by Leaching with Monoethanolamine Solvent Systems

Selective extraction of zinc from high iron-bearing zinc calcine by reduction and magnetization roasting

A novel process that combined reduction roasting with magnetization roasting was developed to intensify the decomposition of zinc ferrite for the selective extraction of zinc from high iron-bearing zinc calcine. The decomposition mechanism of zinc ferritewas investigated in detail by thermodynamics analysis and roasting experiments. The results indicated that 94.65% of the zinc ferrite was decomposed into zinc oxide and ferrous oxide under the optimal reduction roasting conditions of 8 vol.% CO, 750 °C, 50 vol.% CO/(CO+CO2), and 90 min. The generated ferrous oxide was further converted to ferriferrous oxide by magnetization roasting under an air atmosphere at 450 °C for 30 min. After that, 93.62% of zinc contained in the calcine could be selectively extracted by low acid leaching, whereas more than 90% of iron was concentrated in the leaching slag in the form of magnetite, which could be recovered by the subsequent magnetic separation.

Zinc efficiently extracted from zinc calcine by reduced wet grinding: ZnFe2O4 to ZnO and Fe3O4

In traditional zinc metallurgy, the unique spinel structure of zinc ferrite (ZnFe2O4) leads to low zinc leaching efficiency. The reduced wet grinding is adopted to selectively decompose ZnFe2O4 to ZnO, which is easily leached out, and Fe3O4 which is difficult to leach out. The results show that zinc leaching efficiency reached 90.78% under the optimum conditions: mass ratio of H2C2O4·2H2O and ZC 3.60 wt%, ball-to-material ratio 2:1, sulfuric acid concentration 70 g L−1, and liquid-to-solid ratio 10:1 mL g−1, and reduced wet grinding of 60 min and 40 Hz. It is 3, 8, and 10 percentage points higher than that of dry ball milling, reduced leaching (with H2C2O4·2H2O but without mechanical activation), and leaching (without H2C2O4·2H2O and mechanical activation). Reduced wet grinding leads to a reduction in particle size and an increase in the specific surface area of ZC. This further causes a distortion of the ZnFe2O4 lattice, and approximately 42% ZnFe2O4 is reduced to ZnO and Fe3O4. Meanwhile, 92% Zn2SiO4 is also leached. Reduced wet grinding, an enhanced leaching process, results in a higher zinc leaching efficiency and reduces the production of hazardous waste, providing a novel approach for the zinc metallurgic industry in the future.

Research of characterization of zinc ferrite, titanium dioxide and their composites

In this paper, zinc calcines, sulfuric acid, ferric nitrate nine-hydrate, zinc nitrate hexahydrate, titanium oxide sulfate, sodium hydroxide and ammonia water were selected as raw materials, and the methods of sulfuric acid leaching and chemical coprecipitation were used to prepare purified zinc ferrite, synthetic zinc ferrite, synthetic titanium dioxide and its composite with purified zinc ferrite. And characterized by BET, UVVis and FTIR. The results showed that: SO42- existed in purified zinc ferrite. Purified zinc ferrite, synthetic zinc ferrite and purchased had different specific surface area, pore volume and average pore size. The specific surface area of synthetic zinc ferrite decreased with the increase of calcination temperature. The three kinds of zinc ferrite had good absorption of ultraviolet light and visible light. Purchased ferric acid had the strongest absorption of UV light and synthetic zinc ferrite had the strongest absorption of visible light, and purified zinc ferrite had the absorption of UV light and visible light between the two. The specific surface area of titanium dioxide prepared by chemical coprecipitation method was greatly affected by calcination temperature. With the increase of calcination temperature, the specific surface area decreased from 123.633 to 28.036m2·g-1, and the average pore diameter was less affected by calcination temperature. For the zinc ferrite/titanium dioxide composite prepared by chemical coprecipitation method, a certain amount of purified zinc ferrite was added to facilitate the absorption of visible light by titanium dioxide.

Study on preparation and properties of zinc ferrite and titanium dioxide

In this paper, sulfuric acid leaching high iron zinc calcine was used to prepare and purify zinc ferrite, high temperature roasting method was used to prepare synthetic zinc ferrite, and sol-gel method was used to prepare TiO2. The properties of the prepared samples ware characterized by XRD, FT-IR, BET, SEM and other methods. The results show that the synthetic zinc ferrite is pure zinc ferrite, and the purified zinc ferrite contains impurities PbSO4. The TiO2 crystal form prepares at the calcination temperature of 300~550°C is basically the same, and the crystal form transformation occurs at the calcination temperature of 550~600°C. TiO2 samples calcines at 400°C (T400) have higher specific surface area, larger total pore volume and average pore diameter. The crystalline degree of synthetic zinc ferrite is high, the micropores on the crystal surface are closed, and the grains bond with each other. The specific surface area, total pore volume and average pore diameter of purified zinc ferrite are larger than those of synthetic zinc ferrite. The effects of specific surface area, pore volume and pore structure on the adsorption capacity and catalytic efficiency are as follows: T400> purified zinc ferrite > synthesized zinc ferrite.

Study on preparation and properties of zinc ferrite product by leaching from zinc calcine

In this paper, zinc ferrite was prepared from zinc calcine by sulfuric acid leaching, and its properties were studied by the methods of XRD, XRF and SEM/EDS. The results show that sulfuric acid leaching of zinc ferrite from zinc calcine is mainly affected by the initial concentration of sulfuric acid and leaching temperature. If the initial concentration of sulfuric acid and leaching temperature are too low, the soluble oxides in zinc calcine can not be completely dissolved. The prepared zinc ferrite was not suitable for application for too many impurities. However, the higher initial concentration of sulfuric acid and leaching temperature are, the lower recovery of zinc ferrite is. The suitable conditions for preparation of zinc ferrite from zinc calcine by sulfuric acid leaching are liquid-solid ratio 7:1, stirring speed 400rpm, sulfuric acid concentration 160g/L, leaching temperature 85°C, leaching time 120min. The particle size of zinc ferrite is fine, most of them is between 2~5μm. The impurity content of zinc ferrite is less. Zinc ferrite particles are composed of spherical and irregular shape, and they are agglomerate and encase each other.

Microstructure, Mineralogical Characterization and the Metallurgical Process Reconstruction of the Zinc Calcine Relics from the Zinc Smelting Site (Qing Dynasty)

The smelting of zinc is considered as one of the most challenging technologies in ancient civilization. Compared with non-sulfide zinc ores, the smelting of zinc sulfide ores is more complicated since they have to be roasted before smelting. The technological smelting process of the ancient zinc metallurgy technology has been studied and partly reconstructed. However, the roasting technology, including the roasting conditions and involved metallurgical processes, is still unclear. The discovery of the zinc smelting site of Doulingxia dates back to the Qing dynasty (CE 1636–1912), and for the first time provides us with critical archeological evidence to gain an insight into the roasting technology in ancient zinc metallurgy technology. In this paper, the microstructure and mineralogical features of the zinc calcine relics found at the Doulingxia site were characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with X-ray energy dispersive spectrometer (SEM-EDS). To reconstruct the metallurgical process, the original roasting temperature of the unearthed zinc calcine was estimated by thermogravimetric analysis and differential thermal analysis (TG-DTA), combined with reheating experiments and phase composition analysis as well as microstructural analysis. The simulation experiments were conducted to reconstruct the roasting process. The results indicated that the original roasting temperature of the unearthed zinc calcine should be in a range of 650–850 °C, most probably near 750 °C. As long as the retention time is long enough, all sphalerite can be oxidized when the roasting temperature is above 650 °C. The final roasting products mainly include tiny porous particles of ZnFe2O4, Fe2O3, PbSO4, and ZnO. These findings are helpful to reconstruct the ancient zinc metallurgy technology of zinc sulfide ores.

Effects of Operational Parameters on the Low Contaminant Jarosite Precipitation Process-an Industrial Scale Study.

Jarosite precipitation process (JPP) is the most frequently used procedure for iron removal in the hydrometallurgical zinc extraction process. However, there is a gap in the knowledge of the relationship between operational parameters and the low contaminant JPP on the industrial scale. This study will address these issues by investigating the behavior of zinc calcine (ZC) as a neutralizing agent, exploring the source of zinc and iron through leaching experiments, and simulating the Jarosite process of the Bafgh Zinc Smelting Company (BZSC). The results showed that the zinc dissolution efficiency was 90.3% at 90 °C, and 73% of the iron present in the calcine can be solubilized. The main outcome was the iron removal of about 85% by alkaline ions present in ZC without the addition of any precipitating agent. The second target was to evaluate the effect of operational parameters on jarosite precipitation. Results revealed that increasing the temperature to 90 °C and the stirring rate to 500 RPM as well as adjusting the ZC’s pH during the jarosite precipitation remarkably improved iron removal. Considering all these factors in the plant could improve Fe precipitation to around 80% on average.

Isothermal reduction kinetics of zinc calcine under carbon monoxide

Abstract The reduction kinetics of zinc calcine under a CO atmosphere was evaluated by isothermal reductive roasting in a temperature range of 600−800 °C. The extent of reaction of zinc calcine was measured using thermogravimetry (TG), and the decomposition mechanism of zinc ferrite in zinc calcine was analyzed based on variations in the soluble zinc and ferrous contents. The results indicate that the reaction was controlled by the nucleation of the products, with an apparent activation energy of 65.28 kJ/mol. The partial pressure of CO affected the reaction rate more strongly than the CO intensity (defined as PCO/(PCO+PCO2)). The generation rate of zinc oxide was higher than that of ferrous oxide; therefore, the nucleation of ferrous oxide is the rate-determining step of the reaction.

Distilling zinc with zinc sulfide ores: The technology of Qing Dynasty zinc production in Guiyang, Central South China

It is difficult to distill metal zinc partly due to the reduction temperature of zinc oxide ores close to the boiling point of metallic zinc. The treatment of zinc sulfide ores is more complicated since they have to be roasted before smelting. Previous archaeometallurgical studies on zinc smelting technology in China mainly focus on the distillation of zinc oxide ores. This paper, for the first time, presents analytical results of archaeological evidence about the distillation of zinc sulfide ores in Guiyang in southern China dated back to the Qing Dynasty (CE 1636–1912). The smelting remains including ores, distillation retorts and slags, especially the roasting hearths and zinc calcine firstly discovered and confirmed in zinc smelting sites were characterized comprehensively by p-XRF, OM, SEM-EDS and XRD. It was revealed that the zinc smelting technology in the Tongmuling site and the Doulingxia site was mainly based on the distillation of zinc sulfide ores, which should be oxidized by a lengthy roasting processing at the lower temperature before the distilling. In order to enhance the condensation efficiency, the height of the condensers in the distillation retorts has been significantly increased. Most of the zinc products were ordered by the Minting sub-Bureau of Baonan in Changsha.

PURIFICATION PHASES OF ZINC SULPHATE SOLUTION OBTAINED FROM NEUTRAL LEACHING PROCESS OF ZINC CALCINE

The aim of this paper is based in analyze of the zinc sulphate solution obtained from neutral leaching process of zinc calcine in Trepca and its purification from impurities. This solution besides zinc contains also and other impurities such as (Cu, Cd, Co, Ni, As, Ge, Sb, Se, Te, Ag etc.), which are with different concentrations. The sulphate solution can released from metal impurities based on the fact that they have higher electro - chemical potential than zinc and, as such, during the refining process they separate and precipitate in metallic form .Treatment of solution with appropriate technological methods technologically is very important in continuation of the electrolysis process and is accompanied by economic effects, because of non-ferrous and rare metals benefit. In this paper are described the phases of the purification process including acidic purification, cooling, needed materials and equipments for the refining process. Also, special attention is dedicated to the factors that have influence in the process development such as concentration, temperature, time, compressed air, etc.

Extraction of Valuable Metals from High-Iron Zinc Sulfide Concentrate by Reductive Leaching

This study was conducted as part of the development of a new process to recover valuable metals of zinc, copper and indium from high-iron zinc sulfide concentrate (HIZSC) by the reductive leaching of high-iron zinc neutral leaching residue (HIZNLR) with zinc concentrate precipitation of copper with iron powder, neutralization of free sulfuric acid with zinc calcine, precipitation of indium with zinc powder and hematite precipitation to reject iron. Among these stages, reductive leaching is the crucial step, which makes that valuable metals in the materials can be effectively leached and ferric iron in the solution is reduced to ferrous iron. The reductive leachate enables copper, indium and iron separation from the solution in the subsequent process. The results show that by increasing the sulfuric acid concentration, HIZSC addition and prolonging the reaction time, the leaching efficiency of zinc, copper, indium and iron in the sample materials was significantly increased. The maximum metal-leaching efficiency was obtained; 84.3% of the iron was in its soluble ferrous state, and zinc ferrite in the HIZNLR was almost entirely dissolved under the experimental conditions of an H2SO4-to-HIZNLR mass ratio of 1.6, a liquid-to-solid ratio of 11.34 mL/g, a temperature of 90°C, an HIZSC addition of 1.05 times of the stoichiometric amount and a reaction time of 5 h.

Optimization of Microwave-Assisted Oxidation Roasting of Oxide–Sulphide Zinc Ore with Addition of Manganese Dioxide Using Response Surface Methodology

Abstract The present study deals with a microwave-assisted oxidation roasting oxide–sulphide zinc ore technology of with addition of manganese dioxide. Effects of roasting parameters such as MnO2 addition level, roasting temperature, and holding time are studied by using the Central Composite Design (CCD). Meanwhile, zinc calcines are characterized by phase compositions analyses(XRD), structure characteristics of minerals (FT-IR), micro-area chemical analyses (SEM-EDAX) and elemental valence bonding analyses (XPS), which prove to be in accordance with the CCD results. The optimum roasting conditions are decided as MnO2 addition level being 85.14 %, roasting temperature 680 °C, and holding time 41 mins, and oxidation degree of zinc can reach 88.22 %. Besides, when MnO2 addition level reaches a certain value, zinc will aggregate in a form of ZnMn2O4, one battery material.

Sulfuric acid leaching of high iron-bearing zinc calcine

Sulfuric acid leaching of high iron-bearing zinc calcine was investigated to assess the effects of sulfuric acid concentration, liquid- to-solid ratio, leaching time, leaching temperature, and the stirring speed on the leaching rates of zinc and iron. The results showed that the sulfuric acid concentration, liquid-to-solid ratio, leaching time, and leaching temperature strongly influenced the leaching of zinc and iron, whereas stirring speed had little influence. Zinc was mainly leached and the leaching rate of iron was low when the sulfuric acid concentration was less than 100 g/L. At sulfuric acid concentrations higher than 100 g/L, the leaching rate of iron increased quickly with increasing sulfuric acid concentration. This behavior is attributed to iron-bearing minerals such as zinc ferrite in zinc calcine dissolving at high temperatures and high sulfuric acid concentrations but not at low temperatures and low sulfuric acid concentrations.

Role of manganese dioxide in the recovery of oxide–sulphide zinc ore

In this article, the role of MnO2 in the recovery of oxide–sulphide zinc ore discussed. Through adopting various modern analysis techniques (such as X-ray diffraction pattern, X-ray photoelectron spectroscopy, scanning electron microscope, energy dispersive X-ray analysis, and fourier transform infrared spectroscopy), the function and mechanism of MnO2 during the phase transformation process is found out. Thermodynamic mechanisms involved in the phase transformation process with or without addition of manganese dioxide investigated by exploiting the Equilib module of FactSage. What’s more, XRD patterns, XPS spectra and SEM-EDAX analyses of zinc calcines verify well the calculations of FactSage. Results reveal that the addition of MnO2 will produce an aggregation of ZnMn2O4, a valuable energy material, while roasting on its own, results in generating undesirable Zn2SiO4, the oxidation degree being relatively low. Moreover, XRD pattern of zinc calcine and FT-IR spectrum of yellow product collected in the calcination process prove that the sulphur-fixing value of the additive MnO2, which can promote transforming to the elemental sulphur. The volatile S can be collected through a simple guiding device. In this process, the emission of SO2 effectively avoids, thus MnO2 deems as a potential additive in the recovery of oxide–sulphide zinc ore.

Leaching kinetics modelling of reductively roasted zinc calcine

ABSTRACTThe kinetics of the acid leaching of reductively roasted zinc calcine was studied on sample particles with a fine-grained sediment structure. This structure has a porous surface during acid leaching, and the leaching behaviours of roasted zinc calcines are complicated. The leaching of iron is controlled by reactions at the solid–liquid interface with an active energy of 51.40 kJ mol−1, the kinetics model is described by The extraction of zinc could be expressed as with an active energy of 10.01 kJ mol−1 and this process is controlled by diffusion through the porous structure. Temperature is a key factor for the iron extraction, while acidity particle size may play an important role in the leaching of zinc. It is concluded that the selective leaching of zinc is favoured at a high acidity above 90 g L−1 and a low temperature.

Comprehensive recovery of Fe, Zn, Ag and In from high iron-bearing zinc calcine

A beneficiation-metallurgy combination process is developed to recover Zn, Fe and to enrich In, Ag from high iron-bearing zinc calcine based on our former researches. In gaseous reductive roasting process, the roasting conditions were tested by magnetic separation of roasted product. It is found that the \({V_{CO}}\left( {{{{P_{CO}}} \mathord{\left/ {\vphantom {{{P_{CO}}} {{P_{CO + C{O_2}}}}}} \right. \kern-\nulldelimiterspace} {{P_{CO + C{O_2}}}}}} \right)\) in roasting atmosphere should be maintained below 30% to avoid the generation of zinc iron solid solution (Fe0.85-x Zn x O), which can bring a decrease of iron recovery in magnetic separation. After roasting, acid leaching and multistage magnetic separation are carried out for the recovery of Zn, Fe and enrichment of Ag and In. About 90% of zinc is extracted and 83% of iron is recovered in the whole process. The Ag mainly enters the tailings with a recovery of 76%, the Ag grade increases from 0.12 g/t in raw materials to 1.18 g/t in the tailings. However, the In mainly enters the iron concentrations and the recovery reaches 86%. This process was proved to be technically feasible and may be a favorable option in the treatment of high iron-bearing zinc material with high Ag or In content.

Reductive roasting and ammonia leaching of high iron-bearing zinc calcines

ABSTRACTThe separation of iron and zinc is a considerable challenge in the zinc smelting processes. A reduction roasting-ammonia leaching process is proposed in this paper. In roasting experiments, the apparent active energy of the reductive roasting of zinc ferrite is 31-35kJmol−1, and the diffusion of the reactant is the rate-determining step. Zinc ferrite was well decomposed into ZnO and Fe3O4 in reductive roasting. However, byproducts including FeO and Fe0.85−xZnxO were also detected. To achieve a high zinc recovery and to avoid the leaching of FeO, ZnO was selectively extracted via ammonia leaching, while magnetite and ferrous oxide were left in residues and recovered through magnetic separation (MS). The optimal operations of the proposed process were 750°C for 45min under a CO concentration of 8% and a CO intensity of 20%, and leached at 30°C for 1 h with a solid/liquid ratio of 1:7 and a stir speed of 200 revmin−1. A total of 88.56% of the zinc was extracted, and just 1.2% of the iron was extracted. The recovery and grade of iron reached 86.46 and 46.5%, respectively, after MS. This reduction roasting-ammonia leaching process is a favourable option for efficient zinc recovery from high iron-bearing zinc ores.

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.

Optimization Study on the Leaching of High Iron-Bearing Zinc Calcine After Reduction Roasting

The selective leaching of zinc from high iron-bearing zinc calcine after reduction roasting was optimized by Taguchi experimental design method. The experimental parameters and their ranges were 303 to 343 K (30 to 70 °C) for leaching temperature (T), 7 to 15 mL/g for liquid/solid ratio (L/S), 70 to 150 g/L for H2SO4 concentration (C), 5 to 25 minutes for time (t), and 100 to 500 rpm for stirring speed (R). The results show that the optimum conditions were 303 K (30 °C), 9 mL/g, 110 g/L, 20 minutes, and 400 rpm, respectively. Under these conditions, about 92.81 pct Zn was extracted and more than 86 pct Fe was reported into the leach residue. L/S and C had significant effects on the extractions of zinc and iron, while t and R had no significant effects, and T had significant effect on iron extraction but negligible effect on zinc extraction. This indicates that diffusion was not a major control step of the leaching process, and the dissolution of iron was controlled by chemical reaction. The interactive effects of parameters were negligible. The leach residue was mainly composed of Fe3O4 and ZnS, and its particle size was very fine.