Selective Leaching Of Zinc Research Articles

Selective leaching of zinc from carbonate source using glycine as an ecofriendly lixiviant

In the present study, a selective leaching process of zinc from a low-grade carbonate source is proposed by the use of a green lixiviant, namely glycine. Response surface methodology (RSM) coupled with central composite design (CCD), was applied to optimize the levels of glycine concentration, pH and temperature and to quantify the significance of the factors and the interactions among them. Under optimum conditions, glycine concentration = 1.5 M, pH = 9.5 and temperature = 70 ℃, more than 90% of zinc was leached while the leaching percentages of main impurities were negligible. Finally, zinc was removed from the leaching solution through the precipitation process by Na2S solution in the form of ZnS. The thermodynamic aspect of the leaching process was elucidated and it was attempted to justify the results obtained from statistical modeling.

Toward high recovery and selective leaching of zinc from electric arc furnace dust with different physicochemical properties

Toward high recovery and selective leaching of zinc from electric arc furnace dust with different physicochemical properties

Comparison of Butyric Acid Leaching Behaviors of Zinc from Three Basic Oxygen Steelmaking Filter Cakes

The selective leaching of zinc from three different basic oxygen steelmaking (BOS) filter cakes by butyric acid was investigated to compare the leaching behaviors of zinc and further to establish the correlation of the zinc leaching performances and the chemical compositions. The effects of acid concentration and the acid to solid (L/S) stoichiometric ratio were studied, with different optimal leaching conditions obtained. BOS-1 showed the lowest leachability with only less than 10% of zinc removed by 0.5 M acid concentration and 90% of the L/S stoichiometric ratio in 10 h. The best zinc selectivity was achieved with BOS-2 at 51.2% of zinc leaching efficiency, with only 0.47% of iron loss under optimal conditions of 1.5 M acid concentration and a 70% stoichiometric ratio. BOS-3 showed the highest leaching of zinc but the optimal conditions depend on the priority consideration. Using 1.0 M acid and 90% stoichiometric ratio for 10 h, the leaching efficiency of zinc was 84.6% with 20% iron loss. The filter cakes and the leaching residues were characterized. The results indicate different zinc and iron leaching behaviors, which were probably related to the storage conditions, zinc containing phases and the leaching parameters.

Effect of Addition of Other Acids into Butyric Acid on Selective Leaching of Zinc from Basic Oxygen Steelmaking Filter Cake

The selective leaching of zinc over iron from basic oxygen steelmaking (BOS) filter cake was investigated using mixtures of butyric acid with acetic and/or propionic acid, HCl, or H2SO4. The main focus was to assess the effects of other acids on the zinc and iron leaching in butyric acid. The results show that slight reduction of zinc leaching and increase in iron leaching may take place with addition of acetic and propionic acids, causing a minor decrease in the selectivity of zinc leaching over iron. Intermittent addition of H2SO4 and HCl was required to control the pH to be not less than that of pure butyric acid solution. Overall, an excellent selectivity can be maintained with the butyric acid–other acid mixtures. The results demonstrate the feasibility to use raw butyric acid without purification or waste butyric acid containing other impurity acids for leaching of zinc from the BOS filter cake to be recycled. Using high content of H2SO4 in leaching is not recommended because it has a more detrimental effect on the selectivity of zinc leaching and may cause deposition of CaSO4 in the leaching residue which may increase the SO2 or CO2 emission in later high-temperature recycling processes.

Selective leaching of zinc from electric arc furnace dust by a hydrothermal reduction method in a sodium hydroxide system

Electric arc furnace (EAF) dust is a hazardous waste material containing valuable elements, such as zinc (Zn) and iron (Fe), as well as other environmentally harmful elements. In the conventional process, the existence of zinc ferrite (ZnFe2O4) in EAF dust results in a low recovery ratio of zinc and can induce high energy consumption or difficulties utilizing iron resources. In this article, a hydrothermal reduction method in a NaOH system is proposed to recover Zn selectively from EAF dust. First, when pure ZnFe2O4 was used as the input material to test the feasibility of the new method, 70% Zn leaching efficiencies and the isolation of Fe in the residue through the formation of ferroferric oxide (Fe3O4) were achieved at the optimal conditions of 260 °C, 6 M [NaOH], 10 g/L [C6H12O6]n and 50 mL/g of L/S. Second, a leaching process of EAF dust was proposed using the following two procedures: (i) first leaching under normal pressure to dissolve zinc oxide (ZnO); and (ii) second leaching of the first leach residue under hydrothermal reduction conditions to dissolve ZnFe2O4. The leach liquor from the second step was recycled to the first step. Under optimum conditions, the leaching efficiencies of Zn during the first and second leaching were 66.4% and 69.3%, respectively. The total Zn leaching efficiency was calculated to be 89.7%, producing Zn-impregnated leach solution and a leach residue rich in Fe (up to 39.4 wt%) that are suitable as resources for a steel-making plant. However, this process also has its shortcomings owning to larger liquid-solid ratio in the leaching process. Overall, the study technically provides an alternative approach to improve the recycling of zinc and iron and effectively reduce environmental risks from EAF dust.

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.

Synthesis and microstructural properties of zinc oxide nanoparticles prepared by selective leaching of zinc from spent alkaline batteries using ammoniacal ammonium carbonate

Two different precursors of zinc oxide were prepared via the ammoniacal ammonium carbonate leaching of the black mass obtained during the recycling of alkaline batteries. For a concentration of 0.1 mol/L of ammonium in the leaching solution, zinc basic carbonate, was obtained, while for higher ammonium concentrations (0.5 and 1 mol/L), zinc ammonium carbonate was the final product. These precursors were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA/DTG) and Scanning electron microscopy (SEM), and calcined to obtain ZnO. Raman spectroscopy, X-ray diffraction and Transmission electron microscopy (TEM) analysis of the resulting zinc oxide samples indicated a wurtzite hexagonal lattice with a parameter values ranging from 3.23 Å to 3.30 Å, and c parameter values from 5.18 Å to 5.21 Å (values close to typical). The room temperature photoluminescence spectra of the zinc oxide samples showed two main bands: a high energy UV-blue band centred at either 412 or 382 nm (depending on the NH3 concentration of the leaching solution used), and a green band centred at 527 nm. These emission bands are comparable to those reported for pure zinc oxide.

Selective leaching of zinc from blast furnace dust with mono-ligand and mixed-ligand complex leaching systems

The nonferrous metals in blast furnace dust, especially zinc, which used to be categorized as hazardous components for blast furnace, are worthy of recovery in this economy. In this paper, a novel processing for extracting zinc from blast furnace dust by using a coordination reaction between the organic ligand and zinc ions was proposed. When blast furnace dust was leached in a 0.2M iminodiacetic acid (Ida) solution at 20°C for 2h with a liquid-to-solid ratio of 10mL/g, the leaching rates of zinc and iron were 62.78% and 6.07%, respectively. To accomplish the maximum separation of zinc from iron during the leaching process, a mixed-ligand complex leaching system consisting of Ida as the primary ligand and ammonium as the secondary ligand was developed. The optimal conditions for the leaching process with a mixed-ligand complex leaching system were investigated. We found that 65.58% of zinc was extracted by the solution with Ida:NH4Cl:NH3·H2O at 0.2:2:2M and a 20:1 liquid-to-solid ratio at 40°C for 2h.

Selective leaching of zinc from copper-zinc concentrate

Biooxidation of copper-zinc concentrate with the use of consortia of mesophilic and moderately thermophilic acidophilic chemolithotrophic microorganisms was studied. Pyrrhotite, sphalerite, and chalcopyrite were the main sulfide minerals of the concentrate. The possibility in principal of complete selective leaching of zinc from sulfide concentrate coupled with minimal recovery of copper (less than 20%) was demonstrated. Selective leaching of zinc could be caused by galvanic interactions between minerals of the concentrate during the biooxidation. The results can be used as the basis for the development of the technologies for production of grade copper concentrate not containing zinc from sulfide copper-zinc concentrate obtained from refractory ores.

Selective leaching of zinc from hazardous As-bearing zinc plant purification filter cake

This article is part of a continuing endeavor to decrease environmental conflicts and industrial hazards of As-bearing zinc plant hot purification filter cakes (ZPHPFC’s) and to break through this problem and extract Zn selectively from filter cakes to obtain a filtrate containing Zn capable of feeding to zinc electrowinning stage. In this part of research, a process was investigated with a view to selective Zn leaching from ZPHPFC, as well as diminishing the quantity of the ZPHPFC to be dumped. Firstly, pH-dependent leaching tests were done by H2SO4 or NaOH solution with the pH ranging from 1 to 13 to monitor Zn and impurities leaching behaviors and finding suitable pH zone for selective Zn leaching. Then, orthogonal array (OA) of Taguchi's method was employed to arrange the experimental runs in order to distinguish the most notably affecting factors and the optimum leaching conditions for maximizing Zn extraction with minimum impurities dissolution. OA L16 (45) consisting of five factors, each with four levels, was utilized to scrutinize the effects of reaction temperature [T=303, 313, 323, 333 (30, 40, 50, 60) K (°C)], reaction time (t=30, 60, 90, 120min), pH (pH=4.5, 5, 5.5, 6), pulp density (S/L=50, 100, 150, 200g/L), and stirring speed (R=375, 500, 625, 750rpm), on leaching efficiency of the individual metals. Statistical analysis of variance (ANOVA) was done to conclude the relationship between experimental conditions and metals leaching efficiencies. The results showed that increasing pH reduced Zn, Fe and Cd leaching efficiencies. Likewise, increasing of temperature declined extraction of impurities such as Ni, Cd, and Co. Also, time increasing, especially in high temperature, decreased Ni and Co leaching efficiencies. This is due to that conditions in leaching media are suitable for cementation of Ni and Co by metallic zinc that exists in the ZPHPFC in the presence of As. The experimental results for selective leaching showed that under ultimate optimal leaching conditions (T4: 333K (60°C), t4: 120min, pH2: 5, (S/L)3: 150g/L, R3: 625rpm), the leaching efficiency of Zn could be almost 95%, with low dissolution of impurities.

Reductive leaching of zinc, cobalt and manganese from zinc plant residue

Zinc plant residue known as hot filter cake (HFC) contains a significant quantity of zinc oxide (ZnO). In addition, it holds cobalt hydroxide Co(OH)3, manganese dioxide (MnO2) and minor amounts of nickel, copper, iron and lead containing species. The process consists of three unit operations: (i) selective leaching of zinc; where the effects of parameters such as acid concentration (0–1.0M), temperature (40–70°C), time (15–90min) and solid to liquid ratio (S/L) (0.01–0.1gmL−1) are investigated. At this stage, 81.5% of zinc, 2.0% of cobalt and 1.7% of manganese were extracted at the optimum conditions determined. (ii) Reductive leaching of cobalt and manganese; where the leaching residue of step (i) was leached with 1M sulfuric acid solution in the presence of citric acid (C6H8O7.H2O) as a reducing agent. The investigated independent leaching parameters were citric acid content (30–60% more than the stoichiometric ratio), S/L ratio (0.02–0.1gmL−1), temperature (75–95°C) and time (45–75min). Response surface methodology (RSM) was used to optimize the parameters. In the optimum conditions, recovery of cobalt, manganese and zinc was 96.43%, 90.26% and 64.12%, respectively. (iii) Sulfide precipitation; at this stage, in order to separate Co(II), Zn(II) and Mn(II), sodium sulfide (Na2S) 1M was added to the solution from the reductive leaching, at the optimum conditions investigated. Recovery of zinc, cobalt and manganese was 93.45%, 95.15% and 100%, precipitated at pH=2, pH=3 and pH=8, respectively. Finally, based on this research work, a conceptual flowsheet was developed.

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.

Hydrometallurgical extraction of zinc from CaO treated EAF dust in ammonium chloride solution

Zinc in Electric Arc Furnace dust or EAF dust mainly exists as ZnFe2O4 and ZnO. While ZnO can be simply dissolved into either an acidic or alkaline solution, it is difficult to dissolve ZnFe2O4. In our previous work, we introduced a process called “CaO treatment”, a preliminary pyrometallurgical process designed to transform the ZnFe2O4 in the EAF dust into ZnO and Ca2Fe2O5. The halogens and others heavy metals were favorably vaporized during CaO treatment with no essential evaporation loss of zinc and iron, leaving CaO treated dust which consisted mainly of ZnO and Ca2Fe2O5 and no problematic ZnFe2O4 compound. In this work, the selective leaching of zinc over iron and calcium in the CaO treated dust was investigated using an NH4Cl solution. The effects of temperature, reaction time and NH4Cl concentration on dissolution behavior were examined. While most of the zinc in the CaO treated dust was extracted after 2h at 70°C with 2M NH4Cl, only about 20% of calcium was leached in NH4Cl solution. However, the iron did not dissolve and remained as Ca2Fe2O5 in residue. It was confirmed that zinc can be effectively recovered using NH4Cl solution.

Optimization of selective leaching of Zn from electric arc furnace steelmaking dust using response surface methodology

The aim of this work is to investigate and optimize the effects of the leaching parameters on the selective leaching of zinc from electric arc furnace steelmaking dust (EAFD). The response surface method was applied on the basis of a three-level Box–Behnken experimental design method for optimization of selective leaching parameters of zinc from EAFD. The leaching recoveries of zinc (YZn) and iron (YFe) were taken as the response variables, where the concentration of sulphuric acid (X1, mol/L), leaching temperature (X2, °C), leaching time (X3, min), and liquid/solid ratio (X4, mL/g) were considered as the independent variables (factors). The mathematical model was proposed. Statistical ANOVA analysis and confirmation tests were applied. A maximum of 79.09% of zinc was recovered while the minimum iron recovery was 4.08% under the optimum conditions of leaching time 56.42 min, H2SO4 concentration 2.35 mol/L, leaching temperature 25 °C and liquid/solid ratios. By using ANOVA, the most influential factors on leaching of zinc and iron were determined as H2SO4 concentration and leaching temperature, respectively. The proposed model equations using response surface methodology show good agreement with the experimental data, with correlation coefficients (R2) of 0.98 for zinc recovery and 0.97 for iron recovery.

Electrodeposited Nano-flakes of Manganese Oxide on Macroporous Ni Electrode Exhibiting High Pseudocapacitance

A porous nickel (P-Ni) substrate was prepared by selective leaching of zinc from pressed pellets containing powders of Ni & Zn in 4 M NaOH solution. Anodic deposition of manganese oxide onto the porous Ni substrate (/P-Ni) formed nano-flakes of manganese oxide layers as revealed in SEM studies. Pseudocapacitance of this oxide electrode was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CHP) in 2 M NaOH solution. The specific capacitance of the Mn oxide electrode was as high as 1515 F , which was ten times higher than Mn oxide deposited on a flat Ni-ribbon. 80% of capacity was retained after 200 charge/discharge cycles. The system showed no loss of activity in dry form over period of days. The impedance studies indicated highly conducting /P-Ni substance and the obtained specific capacitance from impedance data showed good agreement with the charge/discharge measurements.

Selective leaching of zinc from zinc ferrite with hydrochloric acid

Zinc ferrite is a major constituent of the steel-making dust and sludge. In the present work the hydrometallurgical extraction of zinc from this material was studied. ZnFe 2O 4 and the sludge were leached in hydrochloric acid at atmospheric and elevated pressure using the microwave heating. More than 90% of zinc can be extracted with diluted acid when the temperature is 250 °C retaining iron in the new oxide matrix. The product resulting from the synthetic zinc ferrite contained 91% of hematite and 9% of zinc ferrite. Dried sludge from an oxygen open hearth furnace was converted into hematite containing 0.18% of zinc and 0.05% of lead. This material can be directly recycled or used as a pigment. Over 99% of the zinc was extracted from the sludge with 0.3 M HCl solution but the amount of iron in the solution was higher than for the pure ferrite treatment because the sludge contained also some magnetite and wustite.

Selective Leaching of Zinc from Spent Zinc-Carbon Battery with Ammoniacal Ammonium Carbonate

This paper describes the ammoniacal ammonium carbonate leaching behavior of zinc and manganese from spent zinc-carbon batteries. For selective extraction of Zn from the spent zinc-carbon battery, leaching tests were carried out as a function of process parameters such as concentration of (NH4)2CO3, ammonia, temperature, time and pulp density. Physical methods of separation such as crushing was applied to reduce the material to 10–20 mm size followed by magnetic separation to separate iron with a recovery about 10 mass% leaving most of Zn and Mn in the non-magnetic fraction. Non-magnetic fraction was further subjected to sieving to separate 2.46 mm over and under size fractions. The oversize material was processed by eddy current separation to recover zinc sheet and carbon rods and plastics. The under size material with chemical composition of Zn 15.5 mass%, Mn 17.5 mass%, and Fe 1.4 mass% was used for leaching studies. Under the optimum leaching conditions (2.0 kmol/m 3 (NH4)2CO3 and 4.0 kmol/m 3 ammonia, 40 � C, 100 g/L pulp density, 30 min and 250 rpm), the leaching efficiency of zinc and manganese was 80.2% and less than 0.1%, respectively, indicating the selective recovery of zinc from the spent zinc-carbon battery. An overall zinc recovery is about 88%. [doi:10.2320/matertrans.MRA2008164]

Thermal Treatment of Waste Tire Fly Ash with Polyvinyl Chloride: Selective Leaching of Zinc with Water

Thermal treatment of waste tire fly ash (TFA) with poly(vinyl chloride) (PVC) at temperatures ranging from 160 to 300 °C has been examined for the recovery of metals from TFA in a subsequent leaching process. Thermogravimetric and differential thermal analyses showed that TFA absorbs hydrogen chloride (HCl) released from PVC. X-ray diffraction measurements also indicated that crystalline ZnO contained in TFA converts into chlorides when the mixtures of TFA and PVC are heat-treated at 180 °C or higher temperatures. By heating the mixture (TFA/PVC = 1.5 by weight) at 250 °C for 1 h, the percentage of dechlorinated PVC reaches more than 95%, and more than 90% of the Zn originally contained in TFA is leached from the residue with water. On the other hand, the leaching of Fe in TFA is much suppressed. Compared to a conventional acid-leaching process, satisfactory Zn leaching and selectivity in metal leaching from TFA were realized. This selectivity for Zn is reasonably explained by a difference in the reactivi...

Development of a hydrometallurgical route for the recovery of zinc and manganese from spent alkaline batteries

A hydrometallurgical route is proposed in this paper for the selective separation of zinc and manganese from spent alkaline batteries. The recycling route comprises the following steps: (1) batteries dismantling to separate the spent batteries dust from other components (iron scraps, plastic and paper), (2) grinding of the batteries dust to produce a black homogeneous powder, (3) leaching of the powder in two sequential steps, “neutral leaching with water” to separate potassium and produce a KOH solution, followed by an “acidic leaching with sulphuric acid” to remove zinc and manganese from the powder, and (4) selective precipitation of zinc and manganese using the KOH solution (pH around 11) produced in the neutral leaching step. For the acidic leaching step, two alternative routes have been investigated (selective leaching of zinc and total leaching) with regard to the following operational variables: temperature, time, sulphuric acid concentration, hydrogen peroxide concentration and solid/liquid ratio. The results obtained in this study have shown that the proposed route is technically simple, versatile and provides efficient separation of zinc and manganese.

Hydrometallurgical recovery of zinc from ashes of automobile tire wastes

Study has been performed on the investigation of metal leaching behavior for fly and bottom ashes from automobile tire wastes using acid and alkaline solutions from both viewpoints of environmental protection and resource utilization. The two ashes were found to contain substantial amounts of zinc and iron along with small quantities of cobalt, manganese, magnesium, copper, titanium and aluminum. The fly ash contained a much larger amount of zinc than the bottom ash, and seems to be a promising secondary source for the metal. Effects of such experimental parameters as temperature, time and solid–liquid ratio on the leaching behavior were investigated. Using three mineral acids and citric acid, selective leaching of zinc was successfully attained; the concentration of zinc in the leach liquors from the fly ash reached as high as 20 g l −1 while the iron leaching was much suppressed. Selective separation of zinc was also attained in the leaching with alkaline solutions, though the percent leaching was lower than that in the acid leaching. Moreover, solvent extraction and precipitation were applied to the metal-loaded leach liquors as downstream processing to evaluate the feasibility of zinc recovery.