Papers by Keyword: Acid Leaching

Abstract: An atmospheric leaching of a limonite ore from Soroako, Sulawesi, Indonesia, has been performed using hydrochloric acid (HCl) and nitric acid HNO₃ solutions. The study's objectives are to determine the effect of pre-roasting the laterite ore sample on the dissolution behavior and to compare the leaching efficiency of metals (Ni, Co, and Fe) from limonite under HCl and HNO₃ lixiviants. The sample was characterized using optical microscopic, X-ray diffraction (XRD), X-ray fluorescence (XRF), and atomic absorption spectrometry (AAS) methods. Heating the ore at 300 °C has transformed goethite into proto-hematite, resulting in the highest Ni and Fe leaching efficiency. However, Co leaching efficiency attains the maximum at a roasting temperature of 750 °C. It is shown that HCl leaching for Ni and Fe is more efficient than HNO₃. The higher leaching rate of Fe under HCl indicates low selectivity of iron relative to nickel.

Abstract: Lithium demand has increased rapidly in the last few years because lithium is a metal that is important in technology, like electronic equipment and electric vehicles. One of the primary lithium resources is lithium ore, which contains minerals such as spodumene and lepidolite. Mica schist is one of the lithium ore sources that is indicated to contain lithium. The mica schist used in this research was from Kebumen, Central Java, Indonesia. This raw material indicates a lithium mineral called lepidolite. The aims of this research were to find out the potential of local Indonesian minerals as raw materials for lithium extraction processes in lithium-ion battery (LiB) applications, with the effect of leaching time and solid/liquid ratio. The leaching agent used in this research was 2 M chloride acid (HCl). Variables of this research were-100 mesh for particle size of raw material, 1:5, 1:10, 1:15, and 1:20 (g/ml) for solid/liquid ratio, 30, 60, 90, and 120 minutes for leaching time, and 70 °C for leaching temperature. Inductively Coupled Plasma (ICP-OES) analysis was done on this research to determine the mica-schist composition. The optimum lithium percentage that was obtained in this research was 40.65% on a solid/liquid ratio of 1:5 (g/ml) and a leaching time of 120 minutes.

Abstract: The utilization of geothermal silica as the silica source to synthesize silicone as lithium-ion battery anode component was comprehensively studied. Silicone conversion was performed using magnesiothermic reduction at a temperature of 650 °C for 7 h. The applied Mg:SiO₂ mole ratio on magnesiothermic reduction were 1.6:1, 2:1, and 2.5:1. The purification treatments of silicone product were conducted using two stages of acid leaching using HCl and a mixture of HF and acetic acid. In lithium-ion battery anode preparation, the ratio of Si to graphite employed 100:0; 90:10; 50:50; 10:90; and 0:100. The best yield and the conversion of silicone were 26.46% for the yield and 85.60% for the conversion by using 2:1 of Mg:SiO₂ ratio. In the purification treatments, silicone yield of 29.45% with silicone purity of 58.9% was achieved using HCl, and silicone yield of 25.97% with silicone purity of 98% was achieved by using mixed solution of HF and acetic acid. The best battery performance in term of specific capacity was found by applying Si:graphite ratio of 100:0 with the value of first cycle of 358.5 mAh/g in this research. These findings present the reliability and feasibility of the geothermal solid waste and acid leaching treatments to generate the high quality of silicone for lithium-ion battery anode component.

Abstract: Lathe waste is one of the wastes products of metal processing in the metal-turning industry. The most content of lathe waste is a ferrous (Fe) metal, which, if disposed of into the environment, can cause environmental pollution. Fe metal from lathe waste can be used as a Fe precursor in LiFePO₄ synthesis. The extraction of Fe from the lathe waste can be done by the leaching method using acid as the leaching agent. The recovered compounds have great potential to be used as Fe precursors for the LiFePO₄ synthesis. The selection of leaching agent was based on considerations of the price, the effectiveness of Fe extraction, and the advanced recovery process from Fe extraction. The LiFePO₄ synthesis process can be carried out using co-precipitation, hydrothermal, and sol-gel. LiFePO₄ material characterization was carried out to test the yield of the material produced. Synthesized materials were done to test the characteristics by Scanning Electron Microscopy (SEM) and X-Ray Diffractometer (XRD) analysis. SEM analysis aims to describe the shape and particle size of the material in three dimensions. Meanwhile, XRD analysis aims to characterize the material's crystal structure and crystal size by using the Lattice Parameter value. The electrochemical test aims to test electrochemistry to test the capacity of charge/discharge, efficiency, and lithium-ion batteries' stability. The resulting battery capacity from the three methods is close to the theoretical capacity of LiFePO₄, which is 170 mAh/g.

Abstract: The impurity metal of Al in spent hydroprocessing catalyst (Mo-Ni/Al₂O₃) was removed by HCl, and the metals of Mo and Ni were preliminarily enriched. The results show that the leaching efficiency of Al was 88.62%, and the leaching efficiency of Mo and Ni were 16.32% and 28.74%, respectively. The results were achieved under optimal leaching conditions: the particle size was 150 μm, the concentration of HCl was 4 mol/L, the leaching temperature was 90 °C, and the leaching time was 120 min. The kinetics of the leaching behavior of Al showed that the acid leaching reaction of Al was in accorded with the equation 1-2/3X-(1-X) ^2/3=K₂t, R²=0.97734, which was controlled by internal diffusion. X-ray diffraction analysis of the leaching residue revealed the existence of residual metals Mo(MoO₃, MoO₂(ClO₄)₂)and Ni(NiS). The separation of Al from Mo and Ni has been preliminarily realized, which is conducive to further efficient recovery of Mo and Ni.

Abstract: The goal of the present work was to develop hydrometallurgical method based on acid leaching, which makes it possible to perform selective extraction of non-ferrous metals from old flotation tailings. Leaching was performed with sulfuric acid solutions (from 0.5 to 10%) and distilled water. Leaching was carried out using percolators and bottle agitator. Percolators were loaded with 100 g of old tailings, and leaching was performed with 100 mL of acid solutions. Pulp density during agitation leaching (S: L) was 1: 5. Two samples of old flotation samples were studied. The first sample of flotation tailings contained 0.26% of copper, 0.22% of zinc, and 17.4% of iron; while the second sample contained 0.36% of copper, 0.23% of zinc, and 23.2% of iron. Percolation leaching made it possible to extract up to 43 and 47% of Cu and Zn from the first sample. Extraction rate was maximum during the leaching with 1 and 2.5% sulfuric acid solutions. During the agitation leaching, the maximum extraction rate was reached with a 2.5% sulfuric acid solution (52 and 54% Cu and Zn), but the leaching rate with all solutions and distilled water differed insignificantly. Percolation leaching made it possible to extract up to 54 and 37% of Cu and Zn from the second sample of tailings, while agitation leaching made it possible to extract up to 34 and 68% Cu and Zn, respectively. The rate of non-ferrous metals extraction from the second sample with water did not differ significantly from that of obtained in the experiments with sulfuric acid solutions. In all experiments, the increase in the H₂SO₄ concentration led to the increase in concentrations of iron ions in productive solutions, which impedes the extraction of non-ferrous metals from solutions. Thus, it was possible to reach selective leaching of non-ferrous metals and to obtain solutions with relatively low concentrations of iron ions.

Abstract: The goal of the present work was to develop hydrometallurgical approaches based on acid leaching for selective extraction of base metals from the sample of old flotation tailings as well as obtaining solution, which can be used for leaching of substandard copper-zinc concentrate. Old flotation tailings contained 23.2% of iron, 0.36% of copper, and 0.23% of zinc. Copper-zinc concentrate contained 23.8% of iron, 16% of copper, and 5.3% of zinc. Agitation leaching of old flotation tailings with distilled water and sulfuric acid solutions (of 0.5 to 10% H₂SO₄) for 3 h at pulp density of 20% made it possible to extract of 26 to 34% and of 58 to 70% of copper and zinc, respectively. Concentrations of copper and zinc in the pregnant solutions were of 0.19 to 0.25 g/L and of 0.27 to 0.32 g/L, respectively. The increase in H₂SO₄ concentration up to 10% did not lead to significant increase in base metals extraction but led to significant increase in iron ions concentration in the pregnant solutions. Pregnant solution obtained during the leaching with water contained less than 1 g/L of iron ions, while that obtained during the leaching with 10% sulfuric acid contained about 9 g/L of iron ions. Therefore, two-stage acid leaching with water and 10% sulfuric acid was proposed for selective extraction of non-ferrous metals in the first stage and obtaining of ferric iron solution in the second stage. Two-stage leaching at pulp density of 40% with water made it possible to extract 31 and 64% of copper and zinc, respectively. It was shown, that second stage did not allow to increase non-ferrous metals extraction but made it possible to obtain solution containing 11g/L of ferric iron. This pregnant solution was used for oxidative leaching of copper-zinc concentrate. Leaching at 80°C made it possible to extract 13 and 48% of copper and zinc, respectively.

Abstract: In this study, microwave irradiation technology was used for the calcification roasting followed by sulfuric acid leaching process. The effect of roasting temperature, m (CaO)/m (V₂O₅), and roasting time on the leaching ratio of vanadium were investigated and the roasted samples were characterized by TG-DSC, XRD, and SEM. The leaching ratio of vanadium can be significantly enhanced with the increasing in roasting temperature, m (CaO)/m (V₂O₅), and roasting time. The leaching ratio of chromium decreased with roasting temperature and increased with m (CaO)/m (V₂O₅), and roasting time. The optimal roasting parameters were roasting temperature of 850 °C, the m (CaO)/m (V₂O₅) of 0.85, and roasting time of 90 min. Under the optimal roasting parameters, the leaching ratio of vanadium reached 88.81%. While the leaching ratio of chromium is 3.98%. During roasting process, vanadium is oxidized to acid-soluble CaV₂O₅, Ca₂V₂O₇, and CaMgV₂O₇. After leaching, chromium mainly exists in form of chromohercynite (FeCr₂O₄) and chrome-manganese spinel (Mn_1.5Cr_1.5O₄) in leaching residues.

Abstract: Over past decades, titanium dioxide-based materials have been recognized as effectively practical photocatalysts for purification of toxicity waste. However, pure TiO2 photocatalyst is highly active under ultraviolet illumination. In this work, the effort has been focused on the synthesis of titanium-rich materials starting from minerals ores ilmenite ores and leucoxene ores by ball-milling process in combined with hydrochloric acid leaching method with optimized conditions. Crystallinity and morphologies of as-prepared samples were characterized by X-rays diffraction technique and scanning electron microscope. The photocatalytic activities of both derived-materials were studied and compared by degradation of Rhodamine B organic dye as organic toxicity compound under ultraviolet light and visible light. The results illustrate that the leucoxene-derived sample exhibits superior catalytic performance to the sample derived from ilmenite ores due to the greater Ti-content of the starting leucoxene ores.

Abstract: A DFT study of H⁺ effect on CoO(0 1 0) surface was carried out. What could be seen from the inter atomic distance and the density of states (DOS) was: Co-O bonds were broken strongly and H-O bonds formed strongly when one H⁺ was adsorbed on the O atom, and Co-O bonds were not broken and H-O bond not formed strongly when two H⁺ were adsorbed on the O atom, so the Skutterudite acid leaching process cannot be described as two H⁺ were adsorbed on the O atom and formed the H₂O molecules to enter the solution. But that can be described as one H⁺ was adsorbed on the O atom and formed the OH^- to enter the solution, the OH^- was combined with the H⁺ in the solution to form the H₂O molecule.