Recovery of cobalt and molybdenum from spent catalyst using citric acid

Valuable metals play essential roles in various industrial sectors, such as petroleum, petrochemical, and steel industries. Potential secondary resources of these metals can be obtained from spent catalysts, which are a solid waste of the chemical and oil industries. Spent catalysts contain valuable metal compounds such as nickel (Ni), vanadium (V), cobalt (Co), molybdenum (Mo), rhodium (Rh), platinum (Pt), alumina (Al), etc. In this research, the recovery of cobalt and molybdenum from the spent catalyst of Pertamina Refinery Unit IV, Cilacap, Indonesia, was leaching using citric acid. Samples of spent catalyst were analyzed using EDXRF prior to the leaching process. Citric acid at various concentrations of 1.0, 1.5 and 2 M was used as a leaching agent. The leaching experiment was carried out for 300 minutes and sampling was undertaken at 1, 3, 5, 15, 30, 90 and 300 minutes. Each sample was separated between solid and liquid phases using a centrifuge at 400 rpm for 10 minutes. For analysis, 2 ml of the liquid phase was taken and the cobalt and molybdenum concentrations were analyzed using ICP-OES. It was found that at higher the citric acid concentration and temperature, the recovery of cobalt and molybdenum was also higher. The best leaching condition is obtained at a citric acid concentration of 2 M and 60ºC, where recovery of cobalt and molybdenum were 17.35% and 2.27%, respectively.

Comparative Study for Selective Lithium Recovery via Chemical Transformations during Incineration and Dynamic Pyrolysis of EV Li-Ion Batteries

Selective leaching of Li from spent LIBs thermally pretreated by pyrolysis and incineration between 400 and 700 °C for 30, 60, and 90 min followed by water leaching at high temperature and high L/S ratio was examined. During the thermal pretreatment Li2CO3 and LiF were leached. Along with Li salts, AlF3 was also found to be leached with an efficiency not higher than 3.5%. The time of thermal pretreatment did not have a significant effect on Li leaching efficiency. The leaching efficiency of Li was higher with a higher L/S ratio. At a higher leaching temperature (80 °C), the leaching of Li was higher due to an increase in the solubility of present Li salts. The highest Li leaching efficiency of nearly 60% was observed from the sample pyrolyzed at 700 °C for 60 min under the leaching condition L/S ratio of 20:1 mL g−1 at 80 °C for 3 h. Furthermore, the use of an excess of 10% of carbon in a form of graphite during the thermal treatment did not improve the leaching efficiency of Li.

Magnesium extraction of ferronickel slag processed by alkali fusion and hydrochloric acid leaching

A research using ferronickel slag, the by-product of ferronickel production, as raw material for magnesium extraction has been carried out. It is essential to upgrade the value of ferronickel slag instead of used directly for reclamation materials. Moreover, accumulation due to increasing ferronickel demand as well as environmental contamination due to various potencially toxic elements contained in the ferronickel slag could be prevented. The general objective of this study is to utilize the ferronickel slag for magnesium materials. The specific objective is to determine the optimum conditions of magnesium extraction in the process of alkali fusion followed by hydrochloric acid leaching. A novel method for magnesium extraction from ferronickel slag was carried out through reducing silica content followed by acid leaching method. Alkali fusion of the mixture of ferronickel slag and Na2CO3 at 1000 ?C for 60 minutes followed by water leaching at 100 ?C for 60 minutes with solid to liquid percentage of 20 % were carried out to separate the silica. The leaching residue resulted from water leaching was then leached using hydrochloric aid solution to extract magnesium. The leaching temperature and time as well as the hycrochloric acid concentration were varied in the acid leaching process. Alkali fusion process proved can be generated the sodium silicate that can be separated in the water leaching to the leached solution. Meanwhile, the leaching residue was leached using hydrochloric acid to extract the magnesium. The highest magnesium extraction percentage is 82.67% that resulted from an optimum acid leaching condition with temperature of 80 ?C for 30 minutes using 2M HCl solution. Based on the kinetics study, the activation energy (Ea) for the leaching reaction of magnesium at atmospheric pressure between 32?C to 80?C is 9.44 kJ/mol and affected by diffusion and chemical reactions.

Leaching Behaviors of Chromium(III) and Ammonium-Nitrogen from a Tannery Sludge in North China: Comparison of Batch and Column Investigations

Tannery sludge usually has high content of trivalent chromium (Cr(III)) and ammonium-nitrogen (NH4+-N). It is important to make a critical evaluation of the releasing behaviors of Cr(III) and NH4+-N from tannery sludge before its use on improving soil fertility in agricultural applications. For this purpose, static batch and dynamic leaching experiments with different mathematical models were carried out to simulate the Cr(III) and NH4+-N releasing kinetics from tannery sludge sampled in a typical tannery disposal site in North China, and their influencing factors were also discussed. The results showed that a larger solid-liquid ratio, a higher temperature, and a lower pH value of the leaching solution were beneficial for the release of Cr(III) and NH4+-N from the tannery sludge. The release kinetics of Cr(III) and NH4+-N followed parabolic diffusion and simple Elovich models both in the static and dynamic leaching conditions, indicating that the release was a complex heterogeneous diffusion process. The NH4+-N was easy to be leached out and its released amount reached 3.14 mg/g under the dynamic leaching condition (pH 7), whereas the released amount of the Cr(III) was only 0.27 μg/g from the tannery sludge. There was a positive correlation coefficient between dissolved Fe and Cr(III) in the leachate under different leaching conditions, and the calculated average ratio of Fe/Cr(III) concentration was 3.56, indicating that the small amount of the released Cr(III) came from the dissolution of Cr0.25Fe0.75(OH)3 minerals in tannery sludge.

Phase Transformation and Dissolution Behavior of Pyrite in the Roasting-Sulfuric Acid Leaching Process of Vanadium-Bearing Stone Coal

The selective leaching of vanadium and iron has been one of the main concerns in the field of vanadium recovery from stone coal, but the source of iron ions and their release characteristics were still unclear. In this work, the dissolution of pyrite and its roasted product, under conditions in accordance with the vanadium leaching process from stone coal by blank roasting-acid leaching, were studied. The results indicated that the leaching performances of V and Fe in stone coal were significantly correlated, with both depending on the leaching parameters of the H2SO4 concentration, the leaching temperature, the leaching time and the solid to liquid ratio. Under air conditions, with a roasting temperature of 700 °C, the roasted product of pyrite was hematite. Approximately 45% of the roasted product dissolved at its optimal leaching condition—35% higher than that of the raw pyrite. However, any further improvement was difficult, due to the difference in texture between its outer sphere and inner core. The results demonstrated that the roasting treatment led to a significant increase in the release of iron ions during the vanadium leaching process. The pre-removal of pyrite from the raw ore was necessary to reduce the concentration of iron ions in the leachate.

Characterization of mica from bodonchiin gol deposit (Mongolia)

Although there are many mica deposits in Mongolia, there is no substantial study of the composition of the mica and the chemical composition and on their utilization. In this work, we characterized the minerals composition of two different samples which was located on the surface (mica-1) and in 10 m depth from the surface (mica-2) of the Bodonchin river deposit from Altai sum, Khovd province (Mongolia). The main objective of this research work was to prepare nanoporous materials from clay minerals by a different acid leaching condition. In order to evaluate the leaching characteristics, the chemical composition, mineral composition, bonding characteristics and specific surface area of mica samples were determined by X-ray fluorescence, X-ray diffractometer, FTIR and BET method, respectively. The main chemical composition of mica sample-1 consists of silicon dioxide 45.68%, and aluminum oxide 31.22%, potassium oxide 10.51% while mica sample-2 contains silicon dioxide 45.2%, and aluminum oxide 38.5%, potassium oxide 10.31%, respectively. These samples also contained the lesser amount of iron and magnesium. The specific surface areas vary from 13.11 to 14.65 m2/g. The main mineral compound of both mica samples was muscovite (KAl2(AlSi3O10)(OH)2. There is negligible influence of the sample’s location on the chemical and mineralogical compositions of the mica. Бодончийн голын гялтгануурын найрлага, шинж чанарын судалгаа Хураангуй: Монгол оронд гялтгануурын орд газрууд цөөнгүй байдаг хэдий ч гялтгануурын нөөцийг нарийвчлан тогтоож, химийн найрлага болон эрдэс зүйн судалгааг хийсэн дорвитой судалгааны ажил төдийлөн байхгүй байна. Бид энэхүү судалгааны ажилдаа Ховд аймгийн, Алтай сумын Бодончийн голын гялтгануурын ордын ил газрын гадарга (гялтгануур-1) болон гүнийн (гялтгануур-2) гэсэн хоёр дээжийг сонгон авч шинж чанар, эрдэс бүрдэл зэргийг нарийвчлан судаллаа. Энэхүү судалгааны ажлын гол ач холбогдол нь өөрийн орны шаварлаг эрдсийг ашиглан шинэ материал гарган авах буюу өөрөөр хэлбэл, шаварлаг эрдсийг янз бүрийн нөхцөлд хүчлийн уусгалтанд оруулан нано нүх сүвэрхэг материал гарган авах ажлын үндсэн суурь судалгааны материал болох юм.Гялтгануурын дээжнүүдийн химийн найрлагыг рентгенфлуоросценц (XRF), эрдсийн найрлагыг рентгендиффрактометр (XRD), функциональ бүлгүүдийг нил улаан туяаны спектроскопийн арга (FTIR) болон нунтгийн хувийн гадаргуугийн талбайг багажит шинжилгээний аргаар (BET) тус тус тодорхойллоо.Химийн найрлагын хувьд гялтгануур-1 дээжинд цахиурын оксид 45.68%, хөнгөнцагааны оксид 31.22%, гялтгануур-2 дээжинд цахиурын оксид 45.2%, хөнгөнцагааны оксид 38.5% тус тус агуулагдаж байна. Мөн бага хэмжээний төмөр болон магни агуулсан байгааг тогтоолоо. Дээжнүүдийн хувийн гадаргуугийн талбай 13.11 - 14.65 м2/г байна. Гялтгануурын эрдсийн найрлагын судалгаагаар дээрхи 2 дээжинд голлон мусковитын (KAl2(AlSi3O10)(OH)2) төрлийн эрдэс байгааг тогтоолоо. Түлхүүр үг: гялтгануур, мусковит, шаварлаг эрдэс, биотит .

Removal of Mg and MgO By-Products Through Magnesiothermic Reduction of Ti Powder in Self-Propagating High-Temperature Synthesis

Commercial production of titanium involves chlorination using chlorine gas that can be converted to hydrochloric acid by atmospheric moisture and is hazardous to human health. In the titanium production process, self-propagating high-temperature synthesis is one of the process to directly reduce titanium dioxide. In this work, titanium powder was prepared by self-propagating high-temperature synthesis using titanium dioxide as the starting material and magnesium powder as a reducing agent. After the reaction, magnesium and magnesium oxide by-products were then removed by acid leaching under different leaching conditions, leaving behind pure Ti. During each leaching condition, the temperature of the leaching solution was carefully monitored. After leaching, the recovered titanium in the form of a powder was collected, washed with water and dried in a vacuum oven. Detailed compositional, structural, and morphological analyses were performed to determine the presence of residual reaction by-products. It was found that leaching in 0.4 M hydrochloric acid followed by second leaching in 7.5 M hydrochloric acid is the optimum leaching condition. Furthermore, it was also noticed that total volume of solution in 0.4 M hydrochloric acid leaching condition is advantageous to maintain uniform temperature during the process.

Influence of particle size on copper recovery from sulfide ore by the moderately thermophilic microorganisms

The bioleaching of copper ore by the defined moderately thermophilic consortium containing Leptospirillum ferriphilum and Acidithiobacillus caldus was carried out in the bench-scale column. Bioleaching experiments showed that the leaching rate was 25% higher than that of a conventional leaching and the acid consumption was reduced by 33% at the optimal leaching condition. Meanwhile, the effect of different particle sizes on the rate of the copper leaching was also investigated, and it was shown that the particle size affects the bioleaching rate significantly in the range of 5–25 mm, in which approximately 89.27% of copper was extracted at 5–10 mm, while only 57.08% at 15–25 mm. The results obtained by X-ray diffraction (XRD) analysis of the mineral samples before and after microbial and chemical leaching revealed that the decrease in particle size of the minerals resulted in an enhancement of complex microbial interactions. Especially for the particle size of 5–10 mm, a significant amount of elemental sulfur and jarosite formed on the surface of the mineral, while it was further confirmed that critical microbe-mineral interactions have taken place on the mineral surface. The results indicated that mineral particle size is an integral factor to improve the copper recovery from ore in heap leaching operation. This will provide a reference to the heap construction for the bioleaching.

Efficiency of Sulfuric Acid on Selective Scandium Leachability from Bauxite Residue

Bauxite residue (BR) is a well promising resource for critical metals, especially scandium (Sc), a rare and expensive metal with increasing applications in advanced technology. Greek BR seems to significantly favor a commercially viable recovery of Sc combining optimized leaching and advanced separation techniques. Leaching with mineral acids emerges as the dominant selection compared to other techniques. This study investigates an optimized leaching condition set for Sc recovery, using the most advantageous option of sulfuric acid. The main target is to develop a leaching scale-up process to be established in the premises of Mytilineos S.A. (formerly Aluminium of Greece, the largest Greek alumina and aluminum producer), taking into account the feed requirements of a subsequent advanced ion exchanged procedure. Several parameters were studied individually or combined in order to achieve high Sc concentration in the leachate and to ensure selectivity, especially concerning iron. The most significant parameters prove to be the solid-to-liquid ratio (S/L), the final pH value, and the leachate’s recycling. The proposed process, with low molarities of sulfuric acid and ambient conditions, integrates rapidly, leading to high and selective Sc recovery. Finally, a leaching process flow diagram under continuous operation on an industrial scale is developed.