Acid Leaching Method Research Articles

Particle Shape-Based Evaluation of the Leaching of Sphalerite Ore in Dilute Acid Solutions

In this study, the effects of changes in particle shapes on dissolution efficiencies in zinc (Zn) recovery from a lead-zinc (Pb-Zn) ore by acid leaching method were investigated. In the experiments with nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl), particle size (75-106-150 µm), solids ratio (5-10-15-20-25%), leaching time (30-60-120-180-240 min), acid dosage (0.25-0.5-1-2-5 M) and pulp temperature (30-40-50-60-70 oC) parameters were analyzed. Optimum results were obtained under the conditions of 75 µm particle size, 15% solids ratio, 120 min leaching time, 0.5 M acid dosage, and 50°C pulp temperature for H2SO4; 106 µm particle size, 25% solids ratio, 60 min leaching time, 0.5 M acid dosage, and 70°C pulp temperature for HCl; 75 µm particle size, 20% solids ratio, 60 min leaching time, 1 M acid dosage, and 50°C pulp temperature for HNO3. As a consequence of the tests performed under these optimized conditions, 97.32%, 96.38% and 96.06% Zn dissolution efficiencies were obtained. Within the context of particle shape factor research, microscope images of the leaching residues were obtained from the experiments in which the pulp temperature, acid dosage, and leaching time parameters were examined. The samples obtained from the experiments with all three acids were compared with the ore samples, and the impacts of changes in circularity, roundness, and solidity values on dissolution efficiencies were interpreted.

Summary of the Research Progress on Advanced Engineering, Processes, and Process Parameters of Rare Earth Green Metallurgy.

The addition of rare earth metals to aluminum alloys can effectively improve their corrosion resistance and has been widely used in the aerospace and military industries. However, the current methods for the preparation of rare earth metals involve long processing steps, high energy consumption, and high carbon emissions, which severely constrains the development of aluminum alloys. Its output is further developed. To this end, this paper reviews mainstream rare earth production processes (precipitation methods, microemulsion methods, roasting-sulfuric acid leaching methods, electrochemical methods, solvent extraction methods, and ion exchange methods) to provide basic information for the green smelting of rare earth metals and help promote the development of green rare earth smelting. Based on the advantages and disadvantages of each process as well as recent research results, the optimal process parameters and production efficiency were summarized. Studies have concluded that the precipitation method is mostly used for the recovery of rare earth elements and related valuable metals from solid waste; the microemulsion method is mostly used for the preparation of nanosized rare earth alloys by doping; the roasting-sulfuric acid leaching method is mostly used for the treatment of raw rare earth ores; and the molten salt electrolysis method is a more specific method. This is a green and environmentally friendly production process. The results of this study can provide direction for the realization of green rare earth smelting and provide a reference for improving the existing rare earth smelting process.

Comparative Study of Metal Extraction in Different Acid Concentration of Brass Effluent

Metal values including Copper (Cu), Lead (Pb) and Zinc (Zn) have been effectively recovered from brass melting slag through hydrometallurgical treatments employing acid leaching methods utilizing hydrochloric acid (HCl), nitric acid (HNO3), and sulfuric acid (H2SO4). The optimization of recovery efficiency was investigated by varying the concentrations of these acid solutions. Acidic leachants proved highly effective, particularly under elevated temperatures, with percent extraction increasing in the order of nitric, hydrochloric, and sulfuric acid. The proposed method achieved a remarkable recovery efficiency exceeding 96%. Furthermore, the recovered Copper and Zinc products meet standard specifications.

The Properties of Magnesium Silicate Hydrate Prepared from the Magnesium Silicate Minerals in the Earth’s Crust

In order to explore a wider range and lower cost of raw materials for the preparation of magnesium silicate hydrate (M-S-H), an acid-leaching method was employed to extract and separate high-purity magnesium hydroxide (Mg(OH)2) with a purity higher than 97% and amorphous silica with a purity higher than 90% from four types of natural silicate minerals (serpentine, peridotite, zeolite, and montmorillonite). These two intermediate products, which are amorphous silica and magnesium hydroxide, were used to prepare M-S-H, and the influence of curing at two temperatures, 50 °C and 80 °C, on the properties of M-S-H was investigated. The results showed that with the increase in curing temperature, the bound water content, tetrahedral polymerization degree, and Mg(OH)2 content increased. There was a good correlation between the increase in strength and the bound water content of M-S-H. This work provides a possible technological route for expanding the raw materials for preparing magnesium silicate hydrate cementitious materials and utilizing the abundant magnesium silicate minerals in the Earth’s crust.

Pemanfaatan Lumpur Lapindo sebagai Sumber Silika Magnetik untuk Adsorpsi Tumpahan Crude Palm Oil

In this paper, synthesis of silica magnetite adsorbent has been carried out from Lapindo Mud silica and magnetite (Fe3O4) using the template Cetyltrimethylammonium bromide (CTAB) through a microemulsion process. This research aims to determine the adsorption ability of magnetic silica material as an adsorbent for Crude Palm Oil (CPO) with varying contact times of 10, 20, 30, 60, 90 minutes and an adsorbate concentration of 0,2, 0,4, 0,6, 0,8 and 1 gram. Silica is obtained from Lapindo Mud extraction using the acid leaching method using HCl. Magnetite was prepared by mixing ferric chloride and ferrous chloride salts with an alkaline base. Synthesis of magnetic silica adsorbent using CTAB and 1-butanol as a surfactant and co-surfactant, respectively. The characterization results from FTIR and SEM-EDX data identified the presence of silanol (Si-OH) and Fe-O groups, magnetic silica adsorbent showed an irregular morphological pattern, the size tended to be heterogeneous, contained Fe, O and Si elements. The XRD results show that there are peaks in the (200), (311) and (440) planes, the GSA results show that the pore surface area is 37.048 m2/g, the total pore volume is 0.321 cm3/g and the pore diameter is 33.907 nm, which indicates that the pores have a mesoporous structure. Based on this research, the optimum contact time is 60 minutes with adsorption kinetics following the pseudo-second order and Langmuir isotherm with an adsorption capacity of 1.76 mg/g.

Sintesis Natrium Silikat Menggunakan Silika dari Pasir Pantai Bengkalis

Sodium silicate (Na2SiO3) is a chemical industrial material that is widely used as a metal cleaner, adhesive, and as a filler in the detergent, soap and toothpaste industries. Sodium silicate can be synthesized from silica dioxide (SiO2), which can be obtained through an extraction process from materials containing silica such as sand, glass bottle waste or rice husks. In this research, the synthesis of Na2SiO3 was carried out using silica extracted from Bengkalis beach sand using the acid leaching method, with a 3M HCl solution. The results of X-ray fluorescence (XRF) analysis of Bengkalis Beach sand showed that the silica content reached 89.1%. This research aims to determine the effect of the molar ratio of the NaOH reactant to the extracted SiO2 (2:1, 3:1 and 4:1) on the Na2SiO3 produced. The synthesis of Na2SiO3 was carried out using the hydrothermal method at atmospheric pressure, by reacting a 4M NaOH solution with 10 g of silica from Bengkalis sand, by heating at 110oC for an hour and stirring at 600 rpm. A molar ratio of 2:1 is the best ratio which produces 9.427g of Na2SiO3. From analysis using Fourier Transform Infrared (FTIR) spectroscopy, the spectrum patterns obtained are suitable for compounds containing silanol (≡Si-OH) and siloxane (≡Si-O-Si≡) groups. The X-ray diffraction (XRD) pattern of the synthesized compound is in accordance with standard sodium silicate. The Na2SiO3 obtained has a crystal diameter of 44.8 nm with an agglomerate-shaped morpology.

Application of MLR Method and Pearson Correlation on Nickel Extraction from Laterite Using Nitric Acid

Indonesia is a country rich in laterite mining especially in Celebes island and northern Moluccas. Laterite is a mineral rich with precious nickel. Nitric acid leaching has been used for nickel extraction from laterite under the influence of nitric acid concentration (2.0 M, 4.0 M, and 6.0 M) and leaching temperature (65oC, 70oC, and 75oC) during 60 min. at 300 rpm. The preliminary study aims to apply multiple linear regression (MLR) method to examine the dominant effect between acid concentration and leaching temperature on nickel extraction, and also Pearson correlation to study significant correlation between the variables involved (acid concentration, leaching temperature, and nickel concentration). The method and results is related to acid leaching at varied temperature set up as predictors and nickel concentration as dependent variable in the MLR equation using the enter method. The MLR method showed that acid concentration gave significant effect on nickel concentration, however, the leaching temperature showed no significant effect on nickel extraction at t ≤ 0.05. The Pearson correlation showed acid concentration correlated significantly with nickel concentration. The Kolmogrov-Smirnov (K-S) test showed normality for distribution of nickel concentration. The acid leaching method is potential for nickel extraction from laterite using extensive range of acid concentrations and leaching temperatures to improve nickel extraction.

Detoxification of chromium slag using corn stalk for the hierarchical preparation of ultrafine aluminum hydroxide and iron hydroxide

The harmless treatment and resource utilization of chromite ore processing residue (COPR), a consequential byproduct of chromate production, carry profound significance. In this study, corn stalk, an agricultural waste, was used to generate reducing substances through high-temperature and vacuum treatments and was successfully used to detoxify COPR. The acid leaching method combined with multi-step purification was employed to extract iron and aluminum, two crucial metallic elements, from COPR. The successful preparation of iron hydroxide and ultrafine aluminum hydroxide (ATH) was achieved. The prepared ATH has an average particle size of 8.124 μm, with a highly uniform distribution, enabling it to be a promising environmentally friendly inorganic flame retardant. This study not only effectively addresses the issue of pollution caused by COPR but also presents a novel approach to utilizing industrial and agricultural wastes, thereby promoting the maximization of resource utilization.

Acidic leaching kinetics study on vanadium from magnesiation-roasted vanadium slag

In order to promote the industrial application of the magnesiation roasting–acid leaching method, the acidic leaching kinetics of vanadium from magnesiation-roasted vanadium slag was investigated. By combination of XRD, XPS, and SEM, it was revealed that MgSiO3 and most vanadates consumed acid sharply to produce SiO2 and V(V)-containing vanadyl in the initial 10 min. The variation of vanadium extraction efficiency with leaching time was studied to establish the kinetic models for leaching. Results indicated two distinct stages in the leaching process and the kinetics of both stages followed the shrinking core model. The leaching rate in 0−10 min was controlled by both solid product layer diffusion and chemical reactions, while the leaching rate in 10−30 min was controlled only by chemical reactions. Therefore, it is essential to accelerate the mass transfer in initial 10 min and accurately control the temperature in the following 20 min during leaching.

Selective separation of zinc from germanium-bearing iron cake via a roasting–leaching process

Germanium-bearing iron cake (GBIC) produced through the germanium removal process in a zinc smelter is a valuable source of zinc and germanium. However, achieving selective separation of zinc and germanium using pyrometallurgy treatment and sulfuric acid leaching methods is challenging. To address these challenges, this study introduced a novel roasting–leaching process. During roasting, willemite transformed into ammonia-soluble hemimorphite, promoting zinc leaching. This transformation was mainly attributed to the reaction between in situ water in GBIC and willemite within 200–500 °C. Optimal roasting conditions included a particle size range of 49–74 µm, a roasting temperature of 490 °C, and a duration of 4 h. Under optimized leaching conditions—[NH4++NH3] (7 mol/L), NH4+/NH3 molar ratio (2.5), temperature (50 °C), liquid-to-solid ratio (20 mL/g), agitation speed (600 rpm), and time (180 min)—zinc and germanium exhibited leaching yields of 84.92 % and 0.59 %, respectively, in an ammonia–ammonium carbonate system. After three cycles of leaching, the Zn concentration in leachate increased to 20 g/L, facilitating the subsequent recovery of zinc. Moreover, the Ge concentration in the germanium-bearing leaching residue increased by 1.5 times compared with the initial GBIC, making the residue a valuable source of germanium.

Recovery of lithium from solid waste clays of Emet colemanite beneficiation plant by roasting and acid leaching method

Recovery of lithium from solid waste clays of Emet colemanite beneficiation plant by roasting and acid leaching method

A Comparative Study of Solid-State and Co-precipitation Methods for Synthesis of NMC622 Cathode Material from Spent Nickel Catalyst

Nickel, the main raw material for lithium-ion batteries (LIB), is currently the most in-demand metal. The rising need for nickel and current environmental concerns have underscored the importance of recycling waste metal to recover its value. Meanwhile, a significant secondary source with a high metal value is spent catalyst. In this context, the acid leaching method was used to recover nickel from spent catalyst. This study aimed to synthesize Lithium Nickel Manganese Cobalt Oxide 622 (NMC622) from spent catalyst. To determine the optimal method, a comparative analysis was conducted between solid-state and co-precipitation methods. Recycled spent nickel catalyst to be used for cathode material was examined by analytical methods, i.e., XRD, FTIR, SEM-EDX, and electrochemical performance testing. The XRD, FTIR, and SEM-EDX tests produced similar outcomes, consistent with previous reports. However, in the electrochemical test, the co-precipitation method showed a specific capacity two times higher than the solid-state method. The NMC622 from the co-precipitation method (NMC622-CP) yielded a specific discharge capacity of 132.82 mAh.g-1 at 0.1C, while the retention capacity was 70% for 50 cycles at 0.5C.

Removal of chromium from electroplating sludge by roasting-acid leaching and catalytic degradation of antibiotics by its residue

The recycling of electroplating sludge is of great significance to alleviate environmental pollution and resource depletion. However, due to the complex composition of electroplating sludge, especially chromium-containing electroplating sludge is difficult to treat, and the methods for detoxification and resource utilization of chromium-containing electroplating sludge are still lacking. Herein, we extracted chromium from electroplating sludge by a facile and economical roasting and acid leaching method to achieve detoxification, and the remaining detoxification residue was converted into a Fenton-like catalyst, which was used for the degradation of tetracycline to achieve resource utilization. The results showed that the extraction of chromium by this method could reach 93.35%, the resulting catalyst had excellent degradation performance over a wide pH range (3−11), and the removal of tetracycline could reach 98.8% under optimal conditions. Furthermore, cost calculations have shown that this method has cost advantages over traditional processing methods. In this work, an excellent performance catalyst was obtained that can be used for tetracycline degradation along with the detoxification of electroplating sludge, which provides a new route for the harmless treatment and resource utilization of electroplating sludge, with important theoretical fundamental value and potential application prospect.

Recycling different crystal forms of MnO2 from spent Li-ion batteries cathodes for SDZ degradation

Environmental pollution due to antibiotics usage and spent Li-ion batteries is escalating. To solve this issue, MnO2 with different crystalline phases were prepared as catalysts (recovered from spent lithium-ion battery cathode materials) for the degradation of sulfadiazine (SDZ) in this study by acid leaching and hydrothermal methods, respectively. The morphological and structural characteristics of catalysts were examined by XRD, SEM, XPS, and BET. The catalyst MnO2-6 h (β-MnO2) synthesized in six hours by hydrothermal method showed higher performance in destroying SDZ compared to MnO2-3 h (λ-MnO2) obtained by acid leaching method. Over 95% of SDZ was degraded by 0.2 g/L MnO2-6 h, 1 mM peroxymonosulfate (PMS) at pH 6 by pseudo-first-order kinetics. Density Functional Theory (DFT) calculations and related experimental analyses revealed that the main ROS within the MnO2-6 h/PMS system is SO4－·, which contributes about 67.49% to the degradation of SDZ. The high crystallinity and high Mn(III) ratio of MnO2-6 h are the key to the high catalytic activity of MnO2-6 h, which is highly stable and has potential for practical wastewater treatment. The study provides a new approach to managing the solid waste of spent Li-ion batteries and controlling emerging pollutants resulting from heavy antibiotic use.

Recovery of carbon from spent carbon cathode by alkaline and acid leaching and thermal treatment and exploration of its application in lithium-ion batteries.

The spent carbon cathode (SCC) is a hazardous solid waste from aluminum production. It has an abundant carbon source and a unique graphitic carbon layer structure, making it a valuable waste for recycling. This paper uses alkaline and acid leaching methods to report a straightforward way of extracting recovered carbon (RC) from SCC as anode material for lithium-ion batteries (LIBs). The results show that alkaline and acid leaching conditions at 70 °C with 1 M NaOH and HCl solution individually in 6 h and a liquid-solid ratio of 20:1 can result in RC with up to 94.63% carbon content than 49.38% in SCC, exhibiting a typical graphite structure. SCC and RC materials are obtained after calcination at 400 °C in an inert atmosphere and used as anode materials (SCC-400 and RC-400). In this paper, The initial charging specific capacities are 490.0 mA h g-1, 195.4 mA h g-1, and 423.2 mA h g-1and initial coulombic efficiencies (ICE) are 67.8%, 78.9%, and 72.0% of RC-400, SCC, and SCC-400. RC-400 also shows excellent capacity retention and impedance values. This exciting finding provides a viable, non-hazardous, and resourceful method for treating and disposing of SCC from aluminum electrolysis.

Acid-leaching mechanism of electroplating sludge: based on a comprehensive analysis of heavy-metal occurrence and the dynamic evolution of coexisting mineral phases.

Electroplating sludge is a typical heavy metal-containing hazardous waste with tens of millions of tons produced annually in China. Acid leaching is the most common method to extract valuable heavy metals for resource recycling and environmental protection. However, the coexisting elements, which are released from electroplating sludge to the leaching solution, will hinder the recycling of valuable heavy metals. In this work, dynamic acid-leaching experiments, X-ray diffraction analysis, and simulation calculations were conducted. It was found that coexisting elements (mainly Ca, Fe, and Al) account for a large proportion, and calcium salts as coexisting mineral phase (especially CaCO3) are ubiquitous in electroplating sludge. Moreover, the evolution of coexisting mineral phase plays an essential role in the acid-leaching process: (1) the dissolution of CaCO3 contributed a strong acid-neutralization capability and released Ca2+; (2) H2SO4 is the optimal extracting reagent, since it triggered the transformation of calcium salts to CaSO4·2H2O, reducing the Ca2+ concentration; (3) the coexisting elements Fe and Al would form ferrous and aluminum salt minerals with the acid-leaching process, which reduces the leaching of low-value elements. This work provides a new perspective on the acid-leaching mechanism of electroplating sludge, where the evolution of the mineral phase effect the release of valuable heavy metals and coexisting elements. This work also provides as comprehensive information as possible on electroplating sludge and inspires the improvement of the acid-leaching method.

Applicability of Soybean Crude Urease-Calcite Precipitation Method in Various Liquefiable Sandy Soils

Liquefaction is a process in which pore-water pressure generated in the soil, usually by earthquake, is equal or almost equal to the total stress in the soil. This process reduces the effective stress to zero or near-zero, leading to reduction in shear strength and stiffness of soil. Hence, when liquefaction occurs, structures above and within the liquified soil, buildings, bridges, tunnels, docks, underground pipelines, and many other structures can get damaged. Soils which are susceptible to liquefaction are granular soil such as sand and silt. One of the methods that can be adopted to prevent liquefaction is soybean crude urease-calcite precipitation. This method uses urease enzyme in soybean crude as a biocatalyst to hydrolyze urea to produce carbonate ions and ammonium ions. In the presence of calcium ions, the carbonate ions react to produce calcium carbonate (calcite) precipitate. This research investigates the applicability of soybean crude urease-calcite precipitation method to improve various liquefiable sandy soil (fine, medium, coarse sand) at different relative density (40-60%). The soil strength after improvement was evaluated by using unconfined compressive strength (UCS) test, while calcite content was measured using acid leaching method. The results of the UCS test and calcite content analysis varies depending on the type of sand and relative density. The UCS value obtained from medium sand is higher than 50 kPa, potentially sufficient to prevent liquefaction. However, treatment on coarse sand failed to develop UCS, whereas treatment on fine sand produces limited UCS (< 10 kPa).

Graphite Recovery in Spent Lithium-Ion Batteries

Due to their high specific energy density (Wh/kg), high volumetric energy density (Wh/L), and long cycle life, lithium-ion batteries (LIBs) are being widely used. With the rapid growth of demands on LIBs these years, recycling methods are developed to solve the shortages of supply for rare metal cathode materials, especially Li and Co. However, not being evaluated as high-value material, graphite in spent LIBs always gets neglected and is burnt or downcycled which consequently generates CO2 gas as an inescapable result. Recent reports show the market demand for energy storage from Li-ion batteries will reach 400 GWh in the year 2022, which required nearly 3 million tons of graphite, also it is estimated that 3 billion batteries are thrown away each year in America. Considering the raw material making graphite is organic materials from nature with an irreversible process, a vicious circle can’t be broken if graphite doesn’t get recycled. Remarkably, our group has developed a novel closed-loop hydrometallurgical process for recycling end-of-life Li-ion batteries. After developing acid leaching and alkaline sintering methods, recycled graphite with an ultra-high purity (over 99.99%) is obtained for the first time in the hydrometallurgical process. Being successfully scaled up to the industrial level, it’s proved to be a green and high-efficient method in battery recycling. Further economical and efficient modification means are followed, recovering the structure, and improving the stability of recycled graphite to approach the commercial standard. In summary, our research provides a novel maneuver to fully purify and recover recycled graphite, which has great potential to be commercialized.

Treatment of copper-containing leaching residue by sulfation roasting followed by acid/water leaching

This research investigates the extraction of copper from copper-containing leaching residue, which includes 33.45% of copper, 14.14% of iron, 23.87% of sulfur and trace amounts of silver and other elements. Roasting the copper-containing residue under air and oxygen flow convert sulfides into sulfate, followed by water and acid leaching to extract copper. The process parameters, including leaching temperature, sulfuric acid concentration, leaching time, solid-to liquid ratio, and agitation speed, were optimized for both water and acid leaching methods. Results showed that the maximum copper dissolution efficiency was 93.12% with water leaching, and 97.16% with acid leaching. Chemical analysis revealed that the water and acid leaching residue contained 48.13% and 31.64% of iron, respectively. This study provides valuable insights into the process optimization for copper extraction from copper-containing leaching residue, which can inform the development of more efficient and sustainable methods for metal recovery.

Unblocking of NiMo Active Sites for Hydrodesulfurization Catalysts: A Study Focused on Inactive NixSy Segregation

The formation of NixSy/CoxSy phases on the HDS catalyst surface during catalyst preparation poses the following challenges in the HDS reaction: (1) inactive in the reaction, (2) hinder the role of promoters, (3) block the actives sites (NiMoS/CoMoS) at the perimeter, and (4) increase the inert mass on the catalyst surface. Since the formation of NixSy/CoxSy phases is thermodynamically favorable, it is difficult to control this during the catalyst synthesis. In this regard, this work investigates the effect of metal-support interactions and catalyst compositions on NixSy phase separation and removal of NixSy phases from the catalyst surface using acid-leaching method. The HDS activity for NiMo supported on amorphous alumina (NiMo/A-Al2O3) catalysts significantly increased after the acid-leaching treatment by unblocking the active NiMoS sites and increasing the Ni-MoS2 interaction through alumina support leaching. Overall, the HDS activity for leached NiMo/A-Al2O3 catalysts is 25–30% higher than that for conventional NiMo/γ-Al2O3 catalysts.