Zinc Plant Residue Research Articles

A New Feasible Opportunity for Recycling Lead and Silver from Zinc Plant Residues by Flotation.

Millions of tons of zinc plant leach residues (ZPLR) have been stockpiled in Iranian hydrometallurgical zinc plants during the last few decades. Due to the low grades of zinc, lead, and silver in these residues, these residues have been abandoned without treatment. The authors of this paper studied zinc plant leach residues (ZPLR) to propose a flotation process for separating and producing lead and silver concentrate. A response surface methodology (RSM) was employed to obtain six models for optimizing the best conditions for lead recovery, lead grade, zinc recovery, zinc grade, silver recovery, and silver grade. In these models, the effect of the different main variables, including density, flotation time, pH, sodium sulfide dosage, and potassium amyl xanthate dosage, was investigated to optimize grades and recoveries. The studied ZPLRs were categorized into two types based on the disposal time, including new and old residues. The chemical analysis showed that the grades of lead, zinc, and silver in the new residues are higher than in the old residues. In a previous mineralogical study, it was found that silver forms in lead and zinc minerals as a solid solution within their structures. The resulting 3D graphs showed that the interacting variables have significant effects on responses. The ANOVA analysis exhibited the order of model significance to be lead grade (F-value of 36.46) > silver grade (19.76) > lead recovery (7.88) > zinc grade (5.63) > silver recovery (5.58) > zinc recovery (4.83). Based on these models, under the conditions of 1126.26 g/cm3 density, 20.83 min retention time, 9.9 pH, 6 kg/t sodium sulfide, and 749.66 g/t potassium amyl xanthate dosage for a new residue type, the recoveries of lead, zinc, and silver were determined to be 51.10%, 11.13%, and 72.85%, with grades of 38.87% Pb, 8.46% Zn, and 1209.11 g/t Ag, respectively. According to the feasibility study results, the presented work is reasonable in terms of technical, economic, and investment potential.

Exploring Sustainable Pb Recovery from Zinc Plant Residues via Hydrometallurgical Processes: Comparative Analysis of Zinc and Aluminum Powder Cementation

Exploring Sustainable Pb Recovery from Zinc Plant Residues via Hydrometallurgical Processes: Comparative Analysis of Zinc and Aluminum Powder Cementation

Greener and Sustainable Production: Production of Industrial Zinc (II) Acetate Solution and Recovery of Some Metals (Zn, Pb, Ag) from Zinc Plant Residue by Ultrasound-Assisted Leaching

Zinc plant residue (ZPR) contains significant amounts of valuable metal (Zn, Pb, Ag, etc.) compounds, as well as various heavy metals and harmful compounds that pollute the environment. Processing such residues allows for the recovery and reuse of valuable metals, which is crucial for sustainable resource management. This study investigated a two-stage leaching process of Zn, Pb, and Ag recovery from ZPR. The first stage of ultrasonic-assisted leaching of ZPR was applied to produce an industrial selective zinc acetate solution. Leaching experiments were carried out with an ultrasonic device in the presence of acetic acid, known as organic acid. Under optimum leaching conditions, the extraction of Zn and Fe metals was obtained as 76.13% and 1.32% Fe, respectively. According to the Brunauer–Emmett–Teller (BET) analysis results on the original sample and ultrasonic leaching residue (ULR), the BET surface area and micropore area increased. However, the mean adsorption pore width decreased. In the second stage, conventional sodium chloride leaching was applied to recover lead and silver from the remaining solid after the first stage. Under the optimum conditions in this stage, 80.12% of Pb and 96.2% of Ag were extracted. The presence of coordination between Zn2+/AcO− (acetate) and Pb2+/Cl− complexes in the leaching solution was revealed by Raman spectroscopy. Finally, according to the characterization analysis of the final leaching residue, it was determined that iron oxides and silicate species accumulated in the solid. In conclusion, a significant reduction in the rate of pollution and toxic metals in ZPR was noticed.Graphical

Recovery of high-grade cobalt oxide from zinc plant residue (ZPR) generated at zinc processing plants

In the present study, a method for cobalt recovery from Zinc Plant Residue (ZPR) has been developed. First, the residue was leached in a dilute sulfuric acid solution. >90% cobalt and 95% zinc were leached in two hours at room temperature. Then, leach liquor was purified before cobalt precipitation. First, copper and cadmium were removed using zinc dust. >99% copper and 80% cadmium were removed in 30 min at room temperature with slow agitation. Then, dissolved iron was removed using sodium persulfate as an oxidizing agent, and lime was used to maintain pH. Iron was precipitated (∼99%) in 1 h at 60 °C temperature by maintaining pH at 3.5 and Eh at 700 mV. After iron removal, cobalt was precipitated by using sodium persulfate as an oxidizing agent, and sodium hydroxide was used to maintain pH. The cobalt precipitate was calcined and then the final product was obtained with 58% Co. The filtrate, obtained after cobalt precipitation, had a zinc concentration of approximately 69 g/L. About 82% cobalt and 90% zinc were recovered in the entire process.

Insights on hazardous metal bioaccessibility, and groundwater impacted by Zn residues from a legacy mine and risk evaluation of adjacent soils.

This study explored the legacy impact of Zinc plant residues (ZPRs) in Kabwe, Zambia, on the environment and human health, particularly in light of the town's reputation for Pb pollution. ZPRs solid samples and groundwater within and around ZPRs zone were collected from the legacy mine, along with soils in a 10km radius from the mine site. Bioaccessible fractions of Pb and Zn were elucidated by Japanese leaching test (JLT) and simple bioaccessibility extraction test (SBET). Cationic speciation of Pb and Zn from inhalable and ingestible ZPRs particles was investigated via sequential extraction. Groundwater in the ZPRs area showed higher Zn levels (1490mg/L) compared to Pb (1.7mg/L). Elevated Zn concentration were facilitated by the presence of soluble Zn sulfates while Pb was constrained due to its precipitation as anglesite. Groundwater sampled outside the ZPRs area was within the Zambia regulatory limits (< 0.5mg/L for Pb and < 1mg/L for Zn). Inhalation exposure to < 30µm dust particles from ZPRs and soils near the mine indicated negligible risk, with < 3% of bioaccessible Pb in artificial lysosomal fluid. Meanwhile, oral intake of ZPRs particles < 250µm revealed elevated bioaccessible fractions (36% for Pb and 70% for Zn). ZPRs cationic speciation of ingestible particles < 30µm, 30-75µm, 75-150µm and 150-250µm indicated that the bioaccessible Pb predominantly emanated from labile Pb fractions under gastric conditions with pH < 1. This was due to the dissolution of Pb associated with the exchangeable phase, carbonates and iron/manganese oxides; however, only exchangeable/carbonate Pb was bioaccessible at pH < 2. Hazard quotients indicated increased risks of Pb intoxication through the ingestion of ZPRs and soils near the legacy mine, with higher risks observed in children, emphasizing the need to remediate legacy mine wastes to reduce health risks and protect groundwater through monitoring in mining-affected regions.

A New Approach to Nickel Recycling from Zinc Plant Residue: A Morphological and Crystallographic Study on the Effects of Zinc Impurity on the Electrowinning of Nickel

A New Approach to Nickel Recycling from Zinc Plant Residue: A Morphological and Crystallographic Study on the Effects of Zinc Impurity on the Electrowinning of Nickel

Applied novel functionality in separation procedure from leaching solution of zinc plant residue by using non-aqueous solvent extraction

Traditional solvent extraction (SX) procedures limit metal separation and purification, which consist of the organic and aqueous phases. Because differences in metal ion solvation lead to distinct distribution properties, non-aqueous solvent extraction (NASX) considerably expands the scope of solvent extraction by replacing the aqueous phase with alternate polar solvents. In this study, an experimental design approach used non-aqueous solvent extraction to extract cobalt from zinc plant residue. The aqueous phase comprises ethylene glycol (EG), LiCl and metal ions. In kerosene, D2EHPA, Cyanex272, Cyanex301, and Cyanex302 extractants were used as a less polar organic phase. Various factors were investigated to see how they affected extraction, including solvent type, extractant type and phase ratio, pH, Co(II) concentration, and temperature. The results revealed that at a concentration of 0.05 M, the Cyanex301 extractant could achieve the requisite extraction efficiency in kerosene. The optimal conditions were chosen as the concentration of Cyanex 301 (0.05 M), the concentration of cobalt (833 ppm), the pH (3.5), and the percent of EG (80%). As a result, during the leaching process, these systems are advised for extracting and separating a combination of various metal ions.

Selective Hydrochloric Acid Leaching of Zinc, Lead and Silver from Mechanically Activated Zinc Plant Residue

Selective Hydrochloric Acid Leaching of Zinc, Lead and Silver from Mechanically Activated Zinc Plant Residue

Optimization of Cobalt Reductive Leaching from Zinc Plant Residue (ZPR) Using Taguchi Experimental Design Method

Optimization of Cobalt Reductive Leaching from Zinc Plant Residue (ZPR) Using Taguchi Experimental Design Method

Sustainable Management Strategy for Solidification/Stabilization of Zinc Plant Residues (ZPR) by Fly Ash/Clay-Based Geopolymers

Solidification/stabilization (S/S) of acid waste using Ordinary Portland Cement (OPC) is widely implemented, but, due to the impact on climate change, alternative methods are being investigated. In this work, first, the feasibility of using coal fly-ash/clay-based geopolymers for the S/S of Zn plant residues (ZPR), Cadmium Sponge (CS), and Anode Mud (AM) is proposed as a treatment prior to disposal in landfills. Different variables, such as the type of processing, molding (as-received waste), and pressing (dried waste), and activators, a commercial and an alternative residual sodium carbonate, have been studied. The technical and environmental assessments of the S/S process by means of compressive strength and the leaching of critical pollutants have been monitored. Immobilization efficiencies of Cd and Zn higher than 99% have been obtained by dosing 50% of the acid waste, 6 M NaOH solution (20 min contact time), cured at 75 °C (48 h) and at room temperature (28 days), achieving in the leachates pH values of 7 to 10 and [Cd] and [Zn] &lt; 1 and 2.5 mg/kg, respectively. However, alkaline activation increases As leaching, mainly associated with the clay. Secondly, removing clay from the geopolymer formulation, the optimization of geopolymer parameters, acid waste/geopolymer ratio, liquid/solid ratio, and NaOH molar concentration enables obtaining a significant reduction in the release of As and Cd, and Zn is kept at acceptable values that meet the non-hazardous waste landfill disposal limits for the S/S of both acid wastes.

Comprehensive Study on the Mechanism of Sulfating Roasting of Zinc Plant Residue with Iron Sulfates.

Zinc plant residue (ZPR) is a secondary material generated during hydrometallurgical zinc production that contains considerable contents of valuable elements such as Zn, Cu, Fe, Pb, Cd, Ag, In, Ga, Tl. Zinc, copper and accompanying elements in ZPR are in different minerals, mainly in the ferrites. A promising approach for recycling ZPR is the sulfating roasting using iron sulfates followed by water leaching. In this study, the composition of ZPR and the obtained products were thoroughly investigated by various methods including X-ray diffraction analysis (XRD), chemical phase analysis and Mössbauer spectroscopy. The effect of temperature, amount of iron sulfates and roasting time on the conversion of valuable metals into a water-soluble form was thermodynamically and experimentally studied both using pure ferrites and ZPR. Based on the results of time-resolved XRD analysis and synchronous thermal analysis (STA), a mechanism of the sulfation roasting was elucidated. The rate-controlling step of zinc and copper sulfation process during the ZPR roasting was estimated. The sulfating roasting at 600 °C during 180 min with the optimal Fe2(SO4)3∙9H2O addition followed by water leaching enables to recover 99% Zn and 80.3% Cu, while Fe, Pb, Ag, In, Ga retained almost fully in the residue.

Recovery of Zn(II), Mn(II) and Co(II) from the zinc plant residue using the solvent extraction with CYANEX 302 and D2EHPA/TBP: Stoichiometry and structural studies

Zinc plant residues are produced during the zinc cathode production. Impurities such as Co are removed during the “Hot Purification Stage” and the residue from this stage is known as the zinc hot filter cake (HFC) which contains 21.4% (w/w) Zn, 0.55% Co, and 8.3% Mn. A solvent extraction (SX) method was used to extract the metal species from the zinc hot filter cake (HFC) leach solution. First, Zn(II) was extracted up to 96% from the solution by CYANEX 302 diluted in kerosene at 25 °C, the O/A ratio of 1:1 and pH = 2.5. After Zn(II) was effectively removed, the extraction of Mn(II) and Co(II) was investigated using the synergistic effects of TBP with D2EHPA diluted in kerosene. Around 96.6% of Mn(II), at an equilibrium pH of 4, was extracted using the mixture solution of D2EHPA and TBP at the ratio of 1:1. With Zn(II) and Mn(II) separated, a pure Co(II) solution remained. According to the FT-IR measurements and slope analysis method, the reaction between Zn/CYANEX 302 (HA) and Mn/D2EHPA (HB)/TBP was determined. Based on the results, ZnA2(HA) and MnB2.2HB.TBP were determined to be the probable extracted species in the organic phase.

Recycling lead from a zinc plant residue (ZPR) using brine leaching and cementation with aluminum powder.

This research investigated the treatment process of an Iranian zinc plant residue for recycling lead utilizing brine leaching and cementation with aluminum powder. Response surface modeling was employed for this purpose and accordingly, two quadratic mathematical models with R2 of 0.9058 and 0.9463 were identified for relationship between process parameters. The ANOVA and 3D response surface graphs exhibited that the leaching and cementation processes were significantly depended on the interactive effects between influential parameters. The interaction effects of liquid/solid ratio with NaCl concentration, temperature and stirring rate, and quadratic effect of NaCl concentration had the largest impact on the recovery. It was also distinguished that the most impressive parameters on the cementation performance were the linear effect of Al:Pb molar ratio, cementation time and temperature, and the quadratic impact of agitation rate. Additionally, numerical optimization was carried out by desirability function approach and the maximum leaching recovery of lead (77.14%) was achieved at 400 g/L NaCl concentration, 10 mL/g liquid/solid ratio, 300 rpm stirring speed, 50 °C temperature, and 60-min leaching time. Also, the highest cementation efficiency (74.97%) was determined after 75 min at 1.5 Al:Pb molar (stoichiometry) ratio, ~ 420 rpm agitation rate, and 50 °C temperature. Furthermore, thermodynamic conclusions implied an endothermic nature and good affinity of lead toward each two processes.

Pb Recycling Through Leaching, Precipitation, and Cementation from Zinc Plant Residue

This paper presents the hydrometallurgical methods used for the recovery of concentrate and metallic lead from zinc plant residue (ZPR). The ZPR mainly consisting of 9.5% Pb and 7.5% Zn was initially leached by sulfuric acid under the following conditions: leaching temperature 90 °C, leaching time 90 min., sulfuric acid concentration 200 g/l, and solid/liquid ratio 1/5. The zinc recovery obtained was 92.8%, which was finally directed to solvent extraction circuit to produce zinc cathode. Then acidic residue was subjected to alkaline leaching, using sodium hydroxide (NaOH). The lead recovery obtained was 92.58%. For precipitation method by using NaClO, the effects of three important factors including (NaClO/solution) ratio, temperature, and precipitation time were studied and reported. As a result, lead was precipitated in the form of PbO2 with concentrated grade of 72.03% and recovery of 92.31%. Furthermore, aluminum was used for cementation process to produce metallic Pb with grade of 96.11% and total recovery of 87.17%.

Recovery of Cobalt from the Residues of an Industrial Zinc Refinery

The electrolytic production of metallic zinc from processing zinc sulfide concentrates generates a residue containing cadmium, copper, and cobalt that need to be removed from the electrolytic zinc solution because they are harmful to the zinc electro-winning process. This residue is commonly sent to other parties that partly recover the contained elements. These elements can generate revenues if recovered at the zinc plant site. A series of laboratory tests were conducted to evaluate a method to process a zinc plant residue with the objective of recovering cobalt into a salable product. The proposed process comprises washing, selective leaching, purifying and precipitation of cobalt following its oxidation. The process allows the production of a cobalt rich hydroxide precipitate assaying 45 ± 4% Co, 0.8 ± 0.2% Zn, 4.4 ± 0.7% Cu, and 0.120 ± 0.004% Cd at a 61 ± 14% Co recovery. Replicating the whole process with different feed samples allowed the identification of the critical steps in the production of the cobalt product; one of these critical steps being the control of the oxidation conditions for the selective precipitation step.

Microwave assisted chloride leaching of zinc plant residues

Microwave (MW) assisted chloride leaching was studied to remove valuable and heavy metals from two zinc plant residues, i.e. goethite sludge and Zn-leach product.For both materials, NaCl leaching parameters, such as temperature, NaCl concentration, leaching time and addition of acid, were optimized. For goethite sludge, the best efficiencies for Cu (45–47 %), Pb (83–90 %), and Zn (47–58 %) extraction, with a minimal dissolution of matrix elements, were obtained at 200 °C, 300 g/L NaCl and L/S 10. At short leaching times (5 min) the maximal leachability of Cu and Zn was reached, while at longer leaching time (60 min) the Pb extraction increased to 90 ± 1%. Zn leaching was limited due to the presence of stable franklinite (ZnFe2O4).NaCl (280 g/L) leaching of Zn-leach product required the addition of 1 M HCl to improve metal leaching to Ag 52 ± 3 %, Bi 83 ± 1 %, Cd 82 ± 4 %, Sb 39 ± 1 %, Zn 71 ± 2 % at 200 °C, L/S 10 for 30 min. Consequently, matrix dissolution was enhanced. Metal associations in Zn-leach product were statistically investigated. The environmental impact of the MW leached materials was evaluated by a one stage leaching test, which showed a significant overall reduction in heavy metal leachability compared to untreated materials.

Study on extraction and separation of Ni and Zn using [bmim][PF6] IL as selective extractant from nitric acid solution obtained from zinc plant residue leaching

For the ever-growing demand of nickel (Ni) resources in industry, the Ni recovery from the mining residues or waste has received considerable interest. Zinc plant residue contains valuable metals it may be recovered using conventional pyrometallurgical or hydrometallurgical processes. The present communication is focused on the selective recovery of Ni from the real nitric acid leach solution of zinc plant residue by solvent extraction (i.e. 1-Butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) as ionic liquid, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) and diphenylthiocarbazone (dithizone)). At first step, leaching of filter cake with the nitric acid solution was examined experimentally and it was observed that nitric acid as a relatively strong oxidant, can adequately dissolve Ni and Zn. After that, Ni and Zn extraction behavior in the leach solution was studied and the influence of pH and extractant concentration were investigated on the extraction of the metals. The results indicated Ni can be effectively separated by controlling the pH values. Moreover, Ni can be selectively separated using dithizone combined with [bmim][PF6] at pH = 5.5 and the separation factor βNi/Zn can reach 2.27 × 105 in one extraction stage. The extraction mechanism of Ni was investigated using slope analysis and stripping efficiencies 100% have been achieved for Zn and Ni with 2.0 M HNO3. Thus, it can be concluded that the use of [bmim][PF6] as alternatives solvents which have a less significant environmental impact than the usual solvents in terms of emission of vapors is one of the promising approaches for nickel ion extraction from the real leaching solution of zinc plant residue.

Recovery of Manganese from Zinc Smelter Slag

Using a software-based experiment design, the application of the leaching process for the extraction of manganese from Zinc Plant Slag (ZPS) was investigated. In this study, the effect of different parameters, i.e., H2SO4 concentration, pulp density, agitation rate, temperature and reaction time, was investigated. Response Surface Methodology (RSM) based on the Central Composite Design (CCD) has been implemented to consider the main parameters. A hydrometallurgical route to manganese silicate from spent zinc plant residue has been proposed in this investigation. Based on the investigation, Mn can be extracted from ZPS in sulfuric acid without any oxidant agents. The results showed that the optimum conditions of this study are an H2SO4 concentration of 2 mol/L and a solid/liquid ratio of 0.07 g/mL at 50°C for 150 min and an agitation speed of 1000 rpm. A manganese leaching efficiency higher than 83% is reached under these conditions, with a corresponding 22% iron, 23% lead, 68% zinc and 65% aluminum.

Investigation of Properties of Zinc Plant Residue Mechanically Activated in Two Types of Mills

Investigation of Properties of Zinc Plant Residue Mechanically Activated in Two Types of Mills

Investigation of Properties of Zinc Plant Residue Mechanically Activated in Two Types of Mills

Investigation of Properties of Zinc Plant Residue Mechanically Activated in Two Types of Mills