Zinc Residues Research Articles

Recovery Technology of Zinc from Hydrometallurgical Zinc Residues

In this work, it was aimed to select and propose a feasible as well as an applicable method, or series of methods for the extraction of zinc. After determination of the components of the residue, water leaching, acid leaching and roasting-leaching were performed to reclaim Zn. Roasting-leaching was found to be effectively for Zn extraction by controlling acid mass, roasting duration and temperature as parameters. At the optimum conditions, 0.7 times the amount of H2SO4 at 250 °C for 150 min in roasting, 82.05% of initial Zn content was extracted.

Zinc recovery from franklinite by sulphation roasting

Residues from the zinc roast–leach–electrowin process contain zinc mainly as finely dispersed particles of franklinite. Thus, floatation, sulfuric acid leaching, and alkali leaching are ineffective methods for zinc extraction. An efficient technique was used for the extraction of zinc from hydrometallurgical zinc residues by sulfate roasting of a residue–sulfur–oxygen–H 2O mixture followed by water leaching. The effects of various parameters, such as roasting temperature/time, the sulfur amount, leaching time/temperature, and liquid/solid ratio on zinc leaching were studied. Systematic studies indicate that high zinc leaching rate can be achieved under the following conditions: sulfur addition, 1.2 times theoretical value; duration, 2 h; temperature, 250 °C at roasting stage; and room temperature, liquid/solid ratio 4, and duration time 0.5 h at leaching. X-ray diffraction analysis indicates that the zinc-containing compounds convert into water-soluble zinc sulfate after roasting.

Study on Indium Leaching from Indium-Poor Zinc Residue Enhanced by Ultrasonic Treatment

In this paper, orthogonal experiment design method was applied to determine the optimum condition for indium leaching from indium-poor zinc residue in HCl solution. Taking the results of range analysis and the situation of industrial production into consideration, the optimum conditions for conventional leaching are: reaction temperature 70°C, concentration of HCl 6 mol/L, leaching time 1.0 h, and ratio of liquid to solid 8:1. Under the optimum conditions, ultrasonic was used to enhance the leaching process. Compared with the conventional leaching process, this new process can provide better indium recovery, shorter leaching time, and faster leaching rate. The indium extraction of indium-poor zinc residue with ultrasonic treatment is up to 96 %, which is 31.0 % higher than that without ultrasonic treatment. In addition, the normal agitation improves the diffusion of solution in the ultrasonically enhanced leaching experiment.

Study on indium leaching from mechanically activated hard zinc residue

In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x)1/3]2=kt and (1-2x/3)-(1-x)2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled) and 11.65 kJ/mol (activated) within the temperature range of 30?C to 90?C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

Development of a process for the separation of zinc and copper from sulfuric liquor obtained from the leaching of an industrial residue by solvent extraction

This paper describes a study of the separation of zinc and copper from the leach liquor generated in the treatment of the zinc residue (29.6 g/L Zn and 37.4 g/L Cu) by liquid–liquid extraction. In it, the influence of the extractant type and concentration, aqueous phase acidity, contact time and stripping agent concentration were investigated. Organophosphorus extractants (D2EHPA, IONQUEST®801 and CYANEX®272) and the chelating extractants (LIX®63, LIX®984N and LIX®612N-LV) were also investigated. The organophosphorus reagents are selective for zinc, while the chelating extractants are selective for copper. In the experiment, D2EHPA was found to be the best extractant. A sulfuric acid solution was used in the stripping study. Five continuous experiments were carried out until an optimal condition for the separation of the metals Zn and Cu was achieved. Experiment 5 was carried out in three extraction steps, three scrubbing stages and five stripping stages. In this experiment, a pregnant strip solution containing 125 g/L Zn and 0.01 g/L Cu was obtained and the concentration of the metals in the raffinate was 28.3 g/L Cu and 0.49 g/L Zn.

Novel process to recover valuable metals from hydrometallurgical zinc residues

Zinc residues, i.e., byproducts generated in hydrometallurgical zinc plants, contain valuable elements such as zinc, iron, lead, gallium, indium and silver that are not utilized effectively. In this investigation, zinc residues containing 512-g/t silver were processed by flotation to produce concentrate assaying 4,321.6-g/t silver with an 80.96% silver recovery. The flotation tailings were then pelletized and reduced in a rotary kiln at 1,100°C for two hours. During reduction, the zinc, lead and indium were recovered from the fumes. The roasted pellets were then ground and processed in a magnetic separator to obtain gallium- and germanium-rich iron concentrates. The grades of gallium and germanium in the concentrates reached 1,805 and 1,536 g/t, respectively, with recoveries as high as 94.67% and 93.20%, respectively.

Copper/metal ratios in the gills of rainbow trout (Oncorhynchus mykiss) provide evidence of copper exposure under conditions of mixed-metal exposure.

Previous work has suggested that the ratio of copper residues to zinc in the gills of rainbow trout may indicate short-term exposure to increased levels of waterborne copper. However, the effect of exposure to a combination of increased copper and zinc concentrates in the water column was unknown. We exposed rainbow trout to 8 +/- 2 microg L(-1), 40 +/- 2 microg L(-1) and 90 +/- 9 microg L(-1) of waterborne copper and 21 +/- 3 microg L(-1), 129 +/- 40 microg L(-1), and 202 +/- 40 microg L(-1) of waterborne zinc in a 2-factor experiments and gill copper and zinc residues were examined. Other gill parameters analyzed included the concentrations of calcium, magnesium, sodium, and potassium, liver copper and zinc concentrations and plasma copper, calcium, sodium, and potassium are also reported here. Copper residues in the gill filaments were significantly higher in the highest level of copper exposure (high Cu, 4.06 microg g(-1); low Cu 2.41 microg g(-1); 0 Cu 2.01 microg g(-1); P = 0.001), whereas no differences were seen in zinc concentrations at any treatment level. Gill sodium and plasma calcium concentrations were also decreased at the highest waterborne copper concentrations. Although copper-zinc ratios in the gills were significantly different between the highest and lowest copper treatments (P = 0.002, F = 6.59), copper-sodium and copper-magnesium ratios were more sensitive to waterborne copper exposure (P = 0.001, F = 17.91 and P = 0.002, F = 15.45, respectively). These copper-metal ratios may be better indicators of copper loading in the water column.

Zinc solvent extraction in the process industries

The global zinc industry is currently experiencing unprecedented interest in new developments and expansions. While most of the new projects and plant upgrades remain committed to traditional processing technologies, recent advances in zinc solvent extraction have created opportunities for new process routes in the treatment of both primary ore and secondary materials. The production of special high-grade zinc from the complex Skorpion ore, previously considered untreatable, will be the first commercial application of zinc solvent extraction for the mainstream processing of primary ore. This mine-to-metal project promises to become one of the lowest-cost zinc producers. Solvent extraction is also under consideration for several other oxide and sulfide projects in various stages of feasibility. With respect to the processing of secondary materials, new applications of zinc solvent extraction have proved advantageous for the treatment of zinc residues and furnace dust. In contrast to the zinc industry itself, zinc solvent extraction is well established in the refining of other base metals, providing an efficient means of eliminating zinc as an impurity element. Many applications have been for cobalt and nickel refinery operations. More recently, larger-scale applications have been for primary operations, where refined copper, cobalt, and nickel are produced at the mine site. Previously regarded as a waste product in such operations, interest is now being shown in recovering zinc as a valuable by-product in selected flowsheets. The industrial application of zinc solvent extraction is reviewed in this paper. The reagents used for the selective extraction of zinc are discussed to provide the basic rationale for the choice of this separation technique. An historical perspective is given by brief discussions of some early applications. The review then focuses on recent installations and projects under development where zinc solvent extraction features as the key separation step.

US PUMP SHIPMENTS POST MODEST GAINS

Solvent extraction and separation of indium and copper from zinc residue reductive leach liquor containing a high concentration of zinc (ca. 85 g/L) and iron (ca. 35 g/L) was studied. Di-(2-ethylhexyl) phosphoric acid (D2EHPA) and Acorga M5640 were used as extractants for indium and copper, respectively. Indium was preferentially extracted by 15%(v/v) D2EHPA with three-stage extraction using an aqueous/organic (A/O) phase ratio of 6/1. Indium was effectively stripped from the D2EHPA organic phase by 4 M HCl. Copper was subsequently extracted selectively from the indium-extracted solution using 15%(v/v) Acorga M5640 with three-stage extraction using an A/O phase ratio of 2/1. Copper in the loaded Acorga M5640 organic phase was stripped by a synthetic spent electrolyte solution containing 25 g/L Cu and 180 g/L H2SO4. Based on the experimental results, a flowsheet for the separation and recovery of indium and copper from the reductive leach solution was developed and tested. The results showed that 95.4% of indium and 95.5% of copper were extracted, and the measured separation factors βIn/Zn, βIn/Cu, βIn/Fe, βCuZn, and βCuFe were 4979, 1975, 3719, 1719, and 2446, respectively.

Interactions between toxic and essential trace metals in cattle from a region with low levels of pollution.

Studies on the impacts of pollutant metals and metalloids on livestock have largely focused on animals with relatively high levels of exposure. The impact of low-level environmental contamination, which is more common on agricultural land, is largely unknown. The principal aim of the present study was to examine the effects of low-level environmental contamination on trace metal metabolism in cattle from the rural and relatively uncontaminated region of Galicia (NW Spain). Correlations between toxic (cadmium, lead, and arsenic) and essential trace elements (copper and zinc) were evaluated in the tissues (liver, kidney, and muscle) and blood of 494 cattle from throughout Galicia. Cadmium was the toxic element that had the greatest influence on copper and zinc homeostasis. There was a significant positive association between renal cadmium and zinc residues and a significant negative correlation between kidney cadmium and copper. These interactions are likely to be the result of cadmium-induced effects on metallothionein synthesis. Lead and zinc were positively associated in the kidney, although the mechanism of this interaction is uncertain. Arsenic and copper concentrations were strongly correlated with each other in the liver and may indicate that the high copper levels in animals from copper-rich areas in Galicia interfere with their arsenic excretion. The essential metals copper and zinc were also significantly associated with each other in calves but not in cows.

The structure of L-ribulose-5-phosphate 4-epimerase: an aldolase-like platform for epimerization.

The structure of L-ribulose-5-phosphate 4-epimerase from E. coli has been solved to 2.4 A resolution using X-ray diffraction data. The structure is homo-tetrameric and displays C(4) symmetry. Each subunit has a single domain comprised of a central beta-sheet flanked on either side by layers of alpha-helices. The active site is identified by the position of the catalytic zinc residue and is located at the interface between two adjacent subunits. A remarkable feature of the structure is that it shows a very close resemblance to that of L-fuculose-1-phosphate aldolase. This is consistent with the notion that both enzymes belong to a superfamily of epimerases/aldolases that catalyze carbon-carbon bond cleavage reactions via a metal-stabilized enolate intermediate. Detailed inspection of the epimerase structure, however, indicates that despite the close overall structural similarity to class II aldolases, the enzyme has evolved distinct active site features that promote its particular chemistry.

An epidemic of corneal destruction caused by plasma gas sterilization. The Toxic Cell Destruction Syndrome Investigative Team.

Toxic endothelial cell destruction (TECD) syndrome after intraocular ophthalmic surgery is rare and can result from exposure to a variety of toxins. During January 8 to 14, 1998, 6 patients developed TECD with corneal edema associated with unreactive or dilated pupils at Hospital A. A case patient was any Hospital A patient with TECD within 24 hours after surgery during January 5 to 14, 1998 (epidemic period). A control was any hospital A ophthalmic surgery patient without TECD during the epidemic period. The medical records of hospital A ophthalmology surgery patients during the pre-epidemic (ie, September 1, 1997-January 4, 1998) and epidemic periods were reviewed. Inductively coupled plasma atomic emission spectrometry was used to detect trace inorganic elements on sterilized surgical instruments. Cannulated surgical instruments and laboratory rinsates were perfused directly to the corneal endothelium of isolated rabbit and human corneas. Corneal endothelial ultrastructure and swelling were assessed. The rate of TECD at hospital A was higher during the epidemic than pre-epidemic period (6/12 vs 0/118, P<.001). The only change during the periods was the introduction, on November 5, 1997, of a new sterilization method, AbTox Plazlyte, for sterilization of ophthalmic surgery instruments. Findings from spectrometry revealed that copper and zinc residues were higher in instruments sterilized with Plazlyte than in those sterilized with ethylene oxide (median copper value, 7.64 mg/L vs 0.14 mg/L, respectively, P =.02; median zinc value, 5.90 mg/L vs 1.35 mg/L, respectively, P =.2). Corneal endothelial perfusion of Plazlyte sterilized-instrument rinsates or laboratory solution with copper and zinc produced irreversible damage, similar to toxic corneal endothelial destruction, to rabbit and human corneas. A new sterilization method degraded brass to copper and zinc on cannulated surgical instruments resulting in TECD of the cornea. Arch Ophthalmol. 2000;118:1167-1176

Chronic toxicity and hazard assessment of an inorganic mixture simulating irrigation drainwater to razorback sucker and bonytail

We conducted two 90 day chronic toxicity studies with two endangered fish, razorback sucker and bonytail. Swim-up larvae were exposed in a reconstituted water simulating the middle Green River. The toxicant mixture simulated the environmental ratio and concentrations of inorganics reported in a Department of the Interior study for the mouth of Ashley Creek on the Green River, and was composed of nine elements. The mixture was tested at 1X, 2X, 4X, 8X, and 16X where X was the measured environmental concentration (2 μg/L arsenic, 630 μg/L boron, 10 μg/L copper, 5 μg/L molybdenum, 51 μg/L selenate, 8 μg/L selenite, 33 μg/L uranium, 2 μg/L vanadium, and 20 μg/L zinc). Razorback sucker had reduced survival after 60 days exposure to the inorganic mixture at 8X, whereas growth was reduced after 30 and 60 days at 2X and after 90 days at 4X. Bonytail had reduced survival after 30 days exposure at 16X, whereas growth was reduced after 30, 60, and 90 days at 8X. Swimming performance of razorback sucker and bonytail were reduced after 60 and 90 days of exposure at 8X. Whole-body residues of copper, selenium, and zinc increased in a concentration-response manner and seemed to be regulated at 90 days of exposure at 4X and lower treatments for razorback sucker, and at 8X and lower for bonytail. Adverse effects occurred in fish with whole-body residues of copper, selenium, and zinc similar to those causing similar effects in other fish species. Comparison of adverse effect concentrations with measured environmental concentrations showed a high hazard to the two endangered fish. Irrigation activities may be a contributing factor to the decline of these endangered fishes in the middle Green River. ©2000 John Wiley & Sons, Inc. Environ Toxicol 15: 48–64, 2000

Removal of zinc layers from coated steel strip by evaporation

In this research project, basic investigations on the low temperature reactions of the zinc coating layer were performed in different gas atmospheres in order to develop novel methods for zinc removal from scrap material by baking the material at a moderate temperature. The investigations have shown that zinc evaporates effectively into an inert carrier gas of low oxygen potential. The holding time required is about 5 min at 600°C. The zinc residue remaining on the substrate is low, because the diffusion of zinc in α‐Fe proceeds slowly at the given temperatures. Preliminary experiments with an inductively heated vaporizer of laboratory size led to satisfying zinc removal from shreddered scrap material. This result is a recommendation to develop an industrial pilot plant of this kind.

Costs of chronic waterborne zinc exposure and the consequences of zinc acclimation on the gill/zinc interactions of rainbow trout in hard and soft water

AbstractJuvenile rainbow trout were exposed to zinc in both moderately hard water (hardness = 120 mg CaCO3/L, pH = 8.0, Zn = 150 μg/L or 450 μg/L) and soft water (hardness = 20 mg CaCO3/L, pH = 7.2, Zn = 50 μg/L or 120 μg/L) for 30 d. Only the 450 μg/L zinc—exposed fish experienced significant mortality (24% in the first 2 d). Zinc exposure caused no effect on growth rate, but growth affected tissue zinc levels. Whole body zinc levels were elevated, but gills and liver showed no consistent increases relative to controls over the 30 d. Therefore, tissue zinc residues were not a good indicator of chronic zinc exposure. After the 30‐d exposure, physiological function tests were performed. Zinc was 5.4 times more toxic in soft water (control 96 h LC50s in hard and soft water were 869 μg/L and 162 μg/L, respectively). All zinc‐exposed trout had acclimated to the metal, as seen by an increase in the LC50 of 2.2 to 3.9 times over that seen in control fish. Physiological costs related to acclimation appeared to be few. Zinc exposure had no effect on whole body Ca2+ or Na+ levels, on resting or routine metabolic rates, or on fixed velocity sprint performance. However, critical swimming speed (UCrit) was significantly reduced in zinc‐exposed fish, an effect that persisted in zinc‐free water. Using radioisotopic techniques to distinguish new zinc incorporation, the gills were found to possess two zinc pools: a fast turnover pool (T1/2 = 3–4 h) and a slow turnover pool (T1/2 = days to months). The fast pool was much larger in soft water than in hard water, but at most it accounted for &lt;3.5% of the zinc content of the gills. The size of the slow pool was unknown, but its loading rate was faster in soft water. Chronic zinc exposure was found to increase the size of the fast pool and to increase the loading rate of the slow pool.

Solid waste remediation in the metallurgical industry: Application and environmental impact

AbstractThis paper describes problems associated with the remediation of solid metallurgical wastes generated during primary manufacture of major metals (iron, copper, aluminum, zinc and lead). It focuses on three types of solid wastes: slags, dusts and sludges.It has been shown that solid waste remediation technologies, such as stabilization or solidification, incineration, and hydro‐chemical metal recovery, have been applied in the industry and new technologies such as plasma‐ and vitrification‐processing of solid wastes are under development. On the whole, however, solid residue remediation remains relatively uncommon. In addition, currently applied technologies are unable to solve the complex problems of metallurgical solid wastes (e.g., simultaneous destruction of toxins and extraction of multiple metals).A new thermal process applicable to direct ironmaking that would achieve significant utilization of zinc residues has been proposed. It has been suggested that the high‐temperature treatment of wastes in which metallurgical furnaces are used as remediation reactors holds great potential as an alternative disposal method.

Effect of zinc on grain characteristics of draught-resistant rice mutants

Through the use of Instrumental Neutron Activation Analysis (INAA), zinc concentration was determined in kernels resulted on plants of six drought-resistant rice mutant lines fertilized with zinc sulphate. It was found that zinc fertilization increased zinc residues in the kernels with varying concentrations depending on the line, each line reacted and responded to zinc independently. Zinc content in the kernels ranged from 5.63 to 91.4 ppm in the unfertilized control lines. This range was enlarged due to zinc fertilization of the plants to be from 93.51 to 554.53 ppm. It was also noticed that zinc fertilization increased seed heaviness in varying degrees depending on the line itself. This increase may be due to the increase in kernel thickness rather than in kernel width or length.

ChemInform Abstract: Heavy Metals in the Environment. Part 4: An Investigation Into the Solubility of Metal Chlorides in HCl‐Saturated Solutions and the Recycling of High‐Aluminium Zinc Residues in the Zinc Chloride Process.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Heavy Metals in the Environment. Part 5: The Use of High‐Copper Zinc Residues in the Zinc Chloride Process and the Recovery of Copper as Anhydrous Copper(II) Chloride.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Heavy metals in the environment. Part IV: An investigation into the solubility of metal chlorides in HCl‐saturated solutions and the recycling of high‐aluminium zinc residues in the zinc chloride process

AbstractAn investigation into the solubility of aluminium and lead chlorides in HCl‐saturated zinc chloride solutions and the use of high‐aluminium zinc residues in the production of zinc chloride solution is reported. The process developed involves leaching of the high‐aluminium zinc residues with concentrated hydrochloric acid followed by HCl gas treatment to reduce the concentration of aluminium and lead from zinc chloride solutions. The solubility of aluminium and lead chlorides in HCl‐saturated solutions depends on the zinc chloride concentration. The optimum zinc chloride concentration for maximum reduction in the aluminium and lead levels is 30–55% and 53% (w/w) respectively. Under optimum conditions the aluminium and lead concentrations are reduced to less than 0·1 and 0·9 mg cm−3 respectively.