Extraction Of Metals Research Articles

Effect of metals and brominated flame retardants on thermal degradation kinetics of waste printed circuit board

Waste printed circuit board (WPCB) is an indispensable component in any waste electrical and electronic equipment (WEEE). A promising method for recycling WPCB is pyrolysis. To understand the effect of metals and brominated flame retardants (BFR) on WPCB pyrolysis, four samples were prepared, namely (a) raw WPCB (RW), (b) non-metallic WPCB (NM), (c) bromine extracted WPCB (RWBFR_ext) and (d) bromine and metal extracted WPCB (NMBFR_ext). The degradation kinetics study using the isoconversional methods: Friedman, Ozawa-Flynn-Wall (OFW), Kissinger–Akahira–Sunose (KAS), and Starink showed that the extraction of metals exhibited an increase in final degradation temperature and activation energy (Eα), and altered the reaction mechanism (f(a)) whereas, the reduction of BFR reduced initial degradation temperature. The identified kinetic triplets were verified using the reconstruction profiles. The parameters can be used in designing applications and developing an energy-efficient pyrolysis process.

Green and selective recovery process of Mo, V, and Ni from spent hydrodesulfurization catalysts via novel ionic liquids and deep eutectic solvents technology

Ionic liquids (ILs) and deep eutectic solvents (DESs) are promising candidates as viable alternatives in the metal recovery process. Conventional methods predominantly concentrated on the extraction of metals employing ionic liquids or deep eutectic solvents from either acidic or alkaline media subjected to leaching by acids or bases. Therefore, in this work, a novel approach integrating ILs and DES was investigated, wherein the entire sequence from the leaching process to the precipitation step exclusively involves the utilization of DES and ILs. Firstly, the spent hydrodesulfurization (HDS) catalyst underwent leaching with an ionic liquid (IL), which selectively leached molybdenum (Mo) and vanadium (V). Subsequently, the residual material remaining after IL leaching underwent a further leaching process utilizing a deep eutectic solvent (DES) to facilitate the recovery of nickel (Ni). The effect of different parameters on the leaching percentage was studied and optimized for both IL and DES. Vanadium was recovered as NH4VO3 from the loaded IL phase, which was selectively precipitated over molybdenum using NH4Cl solution and molybdenum was precipitated as BaMoO4 by introducing an excess of BaCl2 solution to the filtrate. For the nickel recovery, the residue obtained after leaching using ionic liquid was treated with DES-1 and finally nickel was recovered from the mixture through cementation with aluminum. This study establishes a novel green approach based on IL and DES to recover Mo, V, and Ni from the spent catalysts without roasting and harsh acidic or basic conditions.

Collaborative extraction of valuable components from saprolitic laterite ore through two-stage nitric acid leaching

Saprolitic laterite ore (SLO) is an important Ni resource that also contains high Mg and a small amount of Sc, but traditional extraction techniques cannot achieve the comprehensive utilization of valuable components, especially Mg and Sc. In this work, a new process was proposed to treat SLO through the application of an HNO3 medium. First, E-pH analysis showed that serpentine and part of iron oxide are easily destroyed, and Ni and Co embedded in silicate and Fe-bearing minerals can be also leached. Subsequently, Ni, Mg, Co, and Sc can be efficiently extracted under the HNO3 concentration of 240 g/L, 90 ℃, L/S of 5:1, 2 h, and 200 r/min. Relevant characterization confirmed that serpentine and goethite were almost completely dissolved after leaching. However, magnetite and its alteration intermediates have relatively stable properties and cannot be destroyed. To reduce acid consumption, the leach liquor was supplemented with HNO3 for two-stage leaching. Efficient extraction of valuable metals can be achieved again with the supplemented HNO3 concentration of 192 g/L. A two-stage leaching process can save 120 kg HNO3/t-ore. Finally, a technical route including two-stage HNO3 leaching, adding MgO to adjust pH, and pyrolysis of Mg(NO3)2 to regenerate HNO3 and MgO was suggested.

Sulfuric acid leaching of a complex zinc sulfide concentrate with high copper and lead concentrations under oxygen pressure

ABSTRACT This paper presents the use of an oxygen pressure-based acid leaching process for the selective extraction of basic metals from a complex zinc ore containing high concentrations of lead (6.00%) and copper (2.47%). The effects of leaching temperature, ore particle size distribution, leaching time, liquid-to-solid ratio, and oxygen partial pressure on the leaching efficiencies of zinc and copper were investigated, and the phase transformation behaviour of lead compounds was studied. Under the optimal conditions that is, a particle size of −48/+40 μm, initial sulfuric acid concentration of 150 g/L, liquid-to-solid ratio of 6:1, leaching time of 150 min, leaching temperature of 150°C, and oxygen partial pressure of 0.8 MPa – the leaching efficiencies of zinc, copper, and iron were 98.85%, 82.69%, and 33%, respectively. The leaching residue showed that almost all of the zinc sulfide was dissolved as ZnSO4, and most of the negatively charged bivalent sulfur was converted to zero-valent element sulfur. Through the pressure leaching reaction, galena in the concentrate was converted to lead jarosite (PbFe6(SO4)4(OH)12) and elemental sulfur. The formation of lead jarosite facilitated the removal of a significant portion of iron during leaching, reducing the subsequent purification burden.

Waste control by waste: Extraction of valuable metals from mixed metallurgical dust by boiling furnace roasting

Electric arc furnace dust (EAFD) is a hazardous waste by-product generated during the process of electric furnace steelmaking, which is rich in valuable metal elements. In order to solve the problem of environmental pollution and resource utilization of EAFD, we propose a new process for medium-temperature suspension roasting EAFD and coke dry quenching dust to extract valuable metals. The thermodynamic properties and migration behavior of valuable elements involved in the reaction were analyzed using thermodynamic simulation software FactSage8.1 and thermogravimetric mass spectrometry. The mechanism and kinetic equation of the dezincification process were investigated using the Kissinger method and Coats-Redfern model. The impact of various parameters on the process efficacy and ash fusion characteristics of the material were investigated through boiling furnace experiments. The results demonstrate that elevating the reaction temperature and decreasing the zinc partial pressure is more favorable for reducing and separating zinc. The corresponding kinetic equations for the decomposition of ZnFe2O4 and reduction of ZnO are denoted as dα/dT = 1.69 × 1012exp (−3.37 × 104/T) and dα/dT = 6.76 × 106 exp (−2.08 × 104/T) × (1 − α) [−ln(1 − α)]3/4, respectively. The optimum reaction temperature was 1050 °C, the C/O ratio was 0.8, the reaction time was 40 min, and the ventilation rate was 3500 mL/min. Under these conditions, the material had no liquid phase agglomeration, and the removal rates of zinc and lead were 93.38 % and 98.14 %, respectively. The crude zinc dust with a zinc grade of 87.57 % and the alloy slag with an iron grade of 52.38 % was obtained. The new process utilizes the excellent heat transfer characteristics and fluidization conditions of the boiling furnace to efficiently realize the high-grade recovery of valuable metals in the EAFD, which provides new insights for the clean treatment of zinc-containing waste.

FarView: An in-situ manufactured lunar far side radio array concept for 21-cm Dark Ages cosmology

FarView is an early-stage concept for a large, low-frequency radio observatory, manufactured in-situ on the lunar far side using metals extracted from the lunar regolith. It consists of 100,000 dipole antennas in compact subarrays distributed over a large area but with empty space between subarrays in a core-halo structure. FarView covers a total area of ∼200 km2, has a dense core within the inner ∼36 km2, and a ∼power-law falloff of antenna density out to ∼14 km from the center. With this design, it is relatively easy to identify multiple viable build sites on the lunar far side. The science case for FarView emphasizes the unique capabilities to probe the unexplored Cosmic Dark Ages – identified by the 2020 Astrophysics Decadal Survey as the discovery area for cosmology. FarView will deliver power spectra and tomographic maps tracing the evolution of the Universe from before the birth of the first stars to the beginning of Cosmic Dawn, and potentially provide unique insights into dark matter, early dark energy, neutrino masses, and the physics of inflation. What makes FarView feasible and affordable in the timeframe of the 2030s is that it is manufactured in-situ, utilizing space industrial technologies. This in-situ manufacturing architecture utilizes Earth-built equipment that is transported to the lunar surface to extract metals from the regolith and will use those metals to manufacture most of the array components: dipole antennas, power lines, and silicon solar cell power systems. This approach also enables a long functional lifetime, by permitting servicing and repair of the observatory. The full 100,000 dipole FarView observatory will take 4–8 years to build, depending on the realized performance of the manufacturing elements and the lunar delivery scenario.

Do ferrous iron-oxidizing acidophiles (Leptospirillum spp.) disturb aerobic bioleaching of laterite ores by sulfur-oxidizing acidophiles (Acidithiobacillus spp.)?

The extraction of nickel, cobalt, and other metals from laterite ores via bioleaching with sulfur-oxidizing and ferric iron-reducing, autotrophic, acidophilic bacteria (e.g. Acidithiobacillus species) has been demonstrated under anaerobic as well as aerobic conditions in experiments in different laboratories. This study demonstrated the bioleaching of laterites from Brazil with the addition of elemental sulfur in 2-L stirred-tank bioreactors with pure and mixed cultures of Acidithiobacillus and Sulfobacillus species under aerobic conditions. In particular, a potential disturbance of mineral dissolution under aerobic conditions by ferrous iron-oxidizing acidophiles likely introduced as contaminants in an applied bioleaching process was investigated with Leptospirillum ferrooxidans at 30°C and Leptospirillum ferriphilum at 40°C, at maintained pH 1.5 or without maintained pH leading to an increase in acidity (with pH values <1.0) due to the biological production of sulfuric acid. Despite the proportion of ferrous iron to the total amount of extracted iron in the solution being drastically reduced in the presence of Leptospirillum species, there was a negligible effect on the extraction efficiency of nickel and cobalt, which is positive news for laterite bioleaching under aerobic conditions.

Evaluating the effectiveness of sulfidated nano zerovalent iron and sludge co-application for reducing metal mobility in contaminated soil

Sewage sludge has long been applied to soils as a fertilizer yet may be enriched with leachable metal(loid)s and other pollutants. Sulfidated nanoscale zerovalent iron (S-nZVI) has proven effective at metal sorption; however, risks associated with the use of engineered nanoparticles cannot be neglected. This study investigated the effects of the co-application of composted sewage sludge with S-nZVI for the stabilization of Cd, Pb, Fe, Zn. Five treatments (control, Fe grit, composted sludge, S-nZVI, composted sludge and S-nZVI), two leaching fluids; synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP) fluid were used, samples were incubated at different time intervals of 1 week, 1, 3, and 6 months. Fe grit proved most efficient in reducing the concentration of extractable metals in the batch experiment; the mixture of composted sludge and S-nZVI was the most effective in reducing the leachability of metals in the column systems, while S-nZVI was the most efficient for reducing about 80% of Zn concentration in soil solution. Thus, the combination of two amendments, S-nZVI incorporated with composted sewage sludge and Fe grit proved most effective at reducing metal leaching and possibly lowering the associated risks. Future work should investigate the longer-term efficiency of this combination.

Appraisal of Bioavailability and Immobilization of Constituent Metals in Tannery Solid Waste Biochar in Soil Amendments Using Sunflower

ABSTRACT The huge volume of tannery solid waste (TSW) can be reduced through conversion into tannery solid waste biochar (TSWB). Here, it was used as soil amendment at seven levels and the total metals and their soil bound or exchangeable fractions were determined through sequential extraction. The fate of metals was observed using sunflower as a test plant in a greenhouse trial using field soil amended with six concentrations (0.45–2.7%) of TSWB. The amendment rate of 1.8% proved to be the best for the growth of sunflower. Sequential extraction of metals indicated that 40% or more Cd, Cr and Pb remained in the exchangeable fraction, compared to less than 20% of Cu, Fe and Ni. Copper was mainly bound in the Fe-Mn and organic fractions, while Fe and Ni were mainly bound in the residual fraction. Copper, Fe and Ni were therefore immobilized in TSWB, while Cd, Cr, Pb, Mg and Zn were available as indicated by differential uptake in sunflower. All metals, except Cd, remained within the permissible limit in tissues of sunflower, while all were in permissible limits in the seeds. As a result, TSWB can be used as amendment below 1.8% to grow energy crops like sunflower.

Remediation of sediments contaminated by harmful heavy metals using aluminum sulfate: Sustainable approach for practical applications

Chemical washing could be suitable for the remediation of marine sediments contaminated with harmful heavy metals. Considering green and sustainable remediation (GSR), the application of aluminum sulfate (AS) is intended to reduce the costs and environmental impacts. We extracted harmful heavy metals from manganese nodules using an ion exchange mechanism that occurs when AS dissociates in water. AS in the range from 2 % to 5 % was used. The remediation efficiencies using 5 % AS were found to be the highest, at 91.8 % for Ni and ≥ 100 % for other harmful heavy metals. The Pearson's coefficient evaluation showed that increasing elapsed time did not significantly affect the extraction of harmful heavy metals. Pollutants in post-processing products may not cause secondary pollutions if solidification/stabilization and additional treatments are used. Our results can serve as fundamental data for the actual remediation processes using AS not only for deep-sea mining tailings but also contaminated marine sediments.

Extraction of heavy metals from water using chelating agents: a comprehensive review

Extraction of heavy metals from water using chelating agents: a comprehensive review

Assessment of phytotoxicity bioassay and metal accumulation potential of Ricinus communis L. genotypes during cultivation in iron mine soil of Jharkhand, India

ABSTRACTS Seed germination and early seedling growth are crucial characteristics for determining a plant species ability to survive in stressed soil including mine soil (MS). In the present study, four genotypes of castor bean (Ricinus communis L.) an industrially important bioenergy crop, were grown in iron MS with different treatments of garden soil (GS) (0%, 25%, 50%, 75%, and 100%) to examine germination, growth indices (tolerance index (TI), seedling vigor index (SVI)) and metal accumulation potential. The study recorded significantly high germination, growth and biomass in 75% GS treatments and for the cultivar MSC-55. The TI was highest in 75% GS treatments for all genotypes, with no significant difference. The metal accumulation potential of castor was evaluated for Fe, Pb, Cu and Ni, all of which were detected in high concentration in iron MS. The translocation factors (TF) for Fe and Ni were recorded <1 for all genotypes which imply metals are stabilized in the castor roots, although for Cu and Pb it was found >1. The bioaccumulation factor was recorded highest for Fe (1.224–7.433) and Pb (0.846–9.056) for all genotypes. Furthermore, the root accumulation of Fe, Pb and Ni was observed highest with 8039.20, 177.70 and 88.10 mg kg−1, respectively. The metal extraction ratio (MER) for Fe and Pb showed the highest. Overall, the highest MER was recorded in order of MSC-55 > Leetos > Swati-1515 > Sai-33. The finding of the study indicates that the genotypes MSC-55 followed by Leetos can grow in MS and accumulate multiple metals in their root and shoots and can be employed as phytostabilizers and phytoextractors.

Platinum Group Metals Extraction from Asteroids vs Earth: An Overview of the Industrial Ecosystems, Technologies and Risks

Platinum Group Metals Extraction from Asteroids vs Earth: An Overview of the Industrial Ecosystems, Technologies and Risks

Extraction of heavy metals from copper tailings by ryegrass (Lolium perenne L.) with the assistance of degradable chelating agents

Heavy metal contamination is an urgent ecological governance problem in mining areas. In order to seek for a green and environmentally friendly reagent with better plant restoration effect to solve the problem of low efficiency in plant restoration in heavy metal pollution soil. In this study, we evaluated the effects of three biodegradable chelating agents, namely citric acid (CA), fulvic acid (FA) and polyaspartic acid (PASP), on the physicochemical properties of copper tailings, growth of ryegrass (Lolium perenne L.) and heavy metal accumulation therein. The results showed that the chelating agent application improved the physicochemical properties of copper tailings, increased the biomass of ryegrass and enriched more Cu and Cd in copper tailings. In the control group, the main existing forms of Cu and Cd were oxidizable state, followed by residual, weak acid soluble and reducible states. After the CA, FA or PASP application, Cu and Cd were converted from the residual and oxidizable states to the reducible and weak acid soluble states, whose bioavailability in copper tailings were thus enhanced. Besides, the chelating agent incorporation improved the Cu and Cd extraction efficiencies of ryegrass from copper tailings, as manifested by increased root and stem contents of Cu and Cd by 30.29–103.42%, 11.43–74.29%, 2.98–110.98% and 11.11–111.11%, respectively, in comparison with the control group. In the presence of multiple heavy metals, CA, FA or PASP showed selectivity regarding the ryegrass extraction of heavy metals from copper tailings. PCA analysis revealed that the CA-4 and PASP-7 treatment had great remediation potentials against Cu and Cd in copper tailings, respectively, as manifested by increases in Cu and Cd contents in ryegrass by 90.98% and 74.29% compared to the CK group.

Extraction of Valuable Metals from Titanium-bearing Blast Furnace Slag by Acid Leaching

Extraction of Valuable Metals from Titanium-bearing Blast Furnace Slag by Acid Leaching

Wastewater treatment in semi-arid industries: A focus on technologies and potential for reuse

The aim of this article is to identify, based on a literature review, the most suitable water treatment technologies for the production of reuse water to be used by industries that are often present in the Brazilian semi-arid region. For this research, we selected studies on water treatment with low implementation costs and advanced development for implementation. This study identified water treatment technologies for the production of reuse water in the leather and footwear, textile, metallic and non-metallic mineral extraction and food and beverage industries. The search was carried out in the scientific databases Scopus and Web of Science, with no restrictions on the year of publication. Based on the selected articles, a summary was made of the most suitable water treatment systems for each industrial sector, providing an overview of the treatments recommended for water-scarce regions. Water reuse can be implemented in various industrial activities, including the use of boilers, cooling towers, toilet flushing, local irrigation and reintroduction into the process as a by-product. There are various methods of water treatment, although it is necessary to assess which is most suitable for each type of industry. Aspects such as the amount of effluent generated, the necessary properties of the water to be reused and the cost of the project must be carefully evaluated if the benefits are to be achieved.

PRECIOUS METALS MARKET FORECASTING IN THE CURRENT ENVIRONMENT

The article analyzes trends in the precious metals market. The general characteristics and assessment of the most popular precious metals are given. The key factors influencing the supply and demand of precious metals are analyzed. Precious metals market forecasts have been developed. An analysis of the state of the world gold market in recent years has been carried out. Using the method of comparative analysis, modern trends in the supply and demand of this precious metal were revealed. The dynamics and structure of world gold reserves are considered. The world's precious metal reserves in different countries were also studied. The potential gold reserves in Ukraine are estimated. The production of precious metals in the world was studied. The rating of countries producing precious metals has been compiled. The leaders in this field have been identified based on the criteria of production capacities and growth rates of precious metals extraction. The structure of consumption of precious metals in the world is analyzed. The factors that lead to an increase in the rate of consumption of precious metals in modern conditions are considered. In particular, an increase in the current rate of commissioning of new solar energy capacities and an increase in the use of electric transport have been identified, which has significantly increased the demand for precious metals in the world. The impact on price dynamics of geopolitical and other economic factors, such as changes in trade relations between countries, currency fluctuations, market crises, changes in the monetary policy of central banks in many countries, and, above all, the increase in interest rates by the US Federal Reserve, was also studied. Considering these and other influencing factors, forecasts of the price dynamics of the precious metals market for 2024 and subsequent years were developed using a graphical method.

Distinguishing xenotime and zircon in ores and estimating the xenotime content for on-site analysis

Estimation of the content of the major minerals containing rare earth element (REE) (e.g., xenotime, monazite, and bastnäsite) to extract metal REEs is a critical task for efficient exploration of mines with REE reserves. X-ray-excited optical luminescence (XEOL) imaging is a promising method for estimating the REE-bearing mineral content on-site. However, distinguishing between xenotime and zircon in ores via XEOL imaging is difficult owing to their similar luminescence colors and intensities. This study reveals that XEOL images of ores before and after annealing at 1300 °C can distinguish xenotime and zircon by investigating images obtained via cathodoluminescence (CL), which is the same phenomenon as XEOL except that it used electron bombardment instead of X-ray irradiation. After annealing, zircon exhibits a luminescence intensity stronger than that of xenotime in the CL images. In these images, zircon corresponds to an area with green luminescence whose CL intensity is drastically enhanced by annealing; in contrast, xenotime corresponds to an area with green luminescence whose CL intensity does not change much. The xenotime content in ores can be estimated from the area corresponding to xenotime in the CL images. The exposure time for CL images, which is comparable to XEOL images, is obtained in 30 s. Therefore, the proposed method can be applied to XEOL imaging and used to on-site prescreen ores before precise quantitative analyses, such as inductively coupled plasma mass spectrometry, electron-probe microanalysis, or scanning electron microscopy based on automated mineralogy, which require a large amount of time; thus, the adoption of the proposed method can lead to a drastic reduction in the time required to explore mines reserving REEs.

The Development of Innovated Complex Process for Treatment of Old Flotation Tailings of Copper-Zinc Sulfide Ore.

The possibility of selective Cu and Zn leaching from the sample of old pyrite tailings, which is one of the most widespread types of solid waste forming during non-ferrous metal production, using sulfuric acid solutions and water was studied. It was shown that water leaching provided selective extraction of Cu and Zn and comparatively low iron ion extraction. At the same time, acid leaching provided the obtainment of pregnant solutions with high ferric ion concentration, which can be used for oxidative leaching of substandard copper concentrates. Water and acid leaching also provided increased Au recovery by cyanidation. The results suggest that acid leaching can be an effective approach for processing old flotation tailings, which allows the extraction of base metals from these wastes and treating flotation tailings for subsequent cyanidation. Effective flotation treatment methods should also provide environmental load reduction, which is caused by the long-term storage of metal-bearing wastes.

Prospect of developing a hydrogenic deposit Semizbay

Relevance. The fact that hydrogenic deposits are developed using combined technologies, and the criteria for combining technologies have not been sufficiently developed. Aim. To select the optimal method of deposit development, taking into account the characteristics of the uranium ores composing it. Objects. The Semizbai sandstone deposit, which lies in loose sedimentary rocks, is localized within a 36 km long section with a width of 10 km. Methods. Analysis of the theory and practice of field development, finding dependencies between operational indicators, modeling, methods of mathematical statistics, technical and economic calculations and approbation of some provisions. Results. The authors have given characteristic of systems for developing hydrogenic deposits and substantiated the necessity of combining metal extraction technologies by leaching with traditional technologies in the conditions of the deposit. Alternative technologies for metal leaching using interacting wells and with metal leaching in a pile are detailed. The mechanism and differences in the conditions of uranium leaching in a quicksand array and in a heap was clarified. The authors have carried out comparative characteristic of alternative options for field development, indicating, among other things, their advantages and disadvantages. It was determined that leaching parameters depend on speed and efficiency of opening new reaction areas with a different mechanism for removing uranium from mineral particles. It is proved that the efficiency of the development of hydrogenic deposits is increased by combining the processes of borehole hydro extraction of ores and heap leaching of metals. The authors proposed the model of decision-making sequence with an arbitrary source of information based on the criterion of discounted profit from mining. Conclusions. The results of the study may be in demand when revaluing reserves, modernizing systems for the development and optimization of methods for managing the quality of mining products. The recommended methods of monitoring the combined development of hydrogenic deposits contribute to increasing the completeness of subsurface use.