Papers by Keyword: Leaching

Abstract: One of the high-capacity cathodes is NMC 622, which has a high nickel content. Spent nickel catalyst has a high nickel content. It was used as a source of nickel for synthesizing NMC 622 cathodes. The nickel used as a catalyst was leached using citric acid, and the resulting filtrate was combined with manganese sulfate and cobalt sulfate precursors in a specific ratio. Furthermore, co-precipitation was carried out by adding oxalic acid. The solid from the co-precipitation was separated, dried, and lithiated with lithium carbonate to obtain the NMC 622 cathode. The results of the XRD test on the obtained cathode revealed that the NMC622 material still contained metal impurities and exhibited lower crystallinity compared to commercial NMC622. Electrochemical testing also revealed that the capacity of the obtained cathode was still lower than that of the commercial cathode. The research also provided information that leaching spent nickel catalyst with 1.5 M citric acid resulted in a higher leaching efficiency. In addition, leaching with a citric acid concentration of 1.5 M also produced a cathode that had better physical and electrochemical characteristics than leaching using other concentrations.

Abstract: Pollution problems caused by industrial production of leather tanneries are an important environmental issue. In the present paper we propose to study effects of tannery sludge (TS) addition in manufactured clay bricks applying a mixture design formed by different proportions of four components: Clay, two types of sand and TS. The analysis leads to an optimal practical mixture of around 10% of TS, 20% of sand and 70% of clay and this to remain with an acceptable aspect, an admissible water absorption below 15%, an admissible total shrinkage (drying and after fire) lower than 8%, a tensile strength higher than 5MPa and a thermal conductivity of 0.93 Wm^-1K^-1, 15% lower than the reference mixture with 0% of TS. Experimental results indicate that a temperature cycle firing up to 950°C can lead to higher tensile strength and lower water absorption compared to a cycle that reaches only 850°C. Furthermore, incorporating (TS) in the fired brick manufacturing process can lead to significant energy saving. Additionally, it was observed that a moderate inclusion of TS can enhance evaporation process. Keywords : Mixture design, Tannery Sludge (TS); Clay bricks ; Evaporation ; Strength; Water absorption; Shrinkage; Leaching; Energy.

Abstract: Zircon (ZrSiO₄) is one of Indonesia's most abundant mineral reserves that have yet to be fully utilized since zircon mine production in Indonesia is only 110.000 tons/year while Australia produces zircon up to 500.000 tons/year. Indonesia has 167 million tons of zircon sand reserves, especially in West Kalimantan. One of the most efficient methods of zircon sand processing in terms of energy use and environmental pollution is the alkali fusion of NaOH. This study used zircon sand with NaOH, a stoichiometric ratio of 1:4 (excess 1.5), to be roasted in a muffle furnace at 600°C for 120 min. The following process is washing the frit with water, and the frit is dissolved with aquades with ratio frit: H₂O=1g:10 ml at 30°C and stirring 300 rpm for 60 min. The frit leaching solution is filtered to obtain Na₂ZrO₃. The water-wash product is leached using HNO₃ as the leaching agent with the ratio of water-wash product: HNO₃=1:5, the acid concentration is 6 M, at 90°C, agitation use 260 rpm with the variation of time 60, 120, 180, 240, and 300 minutes. The pregnant leach solution is deposited with NH₄OH and calcinated. According to the results of this experiment, the optimum time to obtain high Zr extraction is 240 minutes. This research produced single-phase zirconia with a cubic crystal structure containing 91.23% ZrO₂ and 1.18% SiO₂.

Abstract: The rare earth element is a critical element in many industrial sectors. Due to unbalanced supply and demand, it is necessary to look for an alternative source. Coal ash is a waste product of power plant combustion. Previous research revealed that coal ash contained levels of rare earth elements. This research uses coal fly ash from the Paiton power plant. The objectives of this study were to determine the effect of the Na₂SO₄ concentration, stirring rate, and temperature on the recovery of REE concentrate. The experiment was conducted in four steps: (1) alkaline leaching, the process was carried out for 2 hours at 90°C with fly ash solid to 8 M NaOH solution ratio of 1:4 to break the aluminosilicate bonds. (2) Acid leaching of residue for 4 hours at 90°C in 3 M HCl. (3) Precipitation of residue to remove the impurities such as Fe using 1 M NaOH at pH 5. (4) Precipitation of filtrate from process (3) using Na₂SO₄ to produce REE concentrate precipitates. The best condition to obtain the highest REE residue is conducting recovery at the concentration of 20% Na2SO4, stirring rate of 500 rpm, and temperature of 50°C, with a yield of 88.72%.

Abstract: Sustainable green new and renewable energy is continuously developed along with the development of cheap and commercially available secondary energy storage such as Li-ion batteries (LIBs). Nickel-rich cathode material obtained from cheap raw materials can significantly reduce the overall LIBs production cost and improve the overall process feasibility. For the first time, Ni-rich cathode material precursor was synthesized from mixed hydroxide precipitate (MHP). Based on MHP characterization test, the nickel content is high but have slight Mn and Mg level. NCM precursors was prepared in three facile steps, i.e., acid leaching using cheap and environmentally friendly organic acids, coprecipitation using oxalic acid, and thermal decomposition of as-prepared oxalate precipitate. Based on FTIR and XRD analysis, high crystalline oxalate dihydrate precipitates were successfully obtained. The morphological feature of the precipitate is significantly affected by the type of leaching solution. Fine metal oxides precursor powders also were successfully prepared which is confirmed by XRD, FTIR, and SEM analysis and can be readily used for Ni-rich cathode material preparation. In this study, NCM-Ox-LA have the best characteristic properties.

Abstract: As a result of titanomagnetite iron ore processing, technogenic waste is formed in the form of vanadium-containing slags. The industrial processing of these slags is important to improve the environmental situation in industrial regions and expand vanadium raw material base. The study purpose was the vanadium extraction from slags of titanomagnetite ore processing (ITmk3 process slag and JSC “EVRAZ NTMK” slag) in the soluble vanadate form. Research tasks: hydrometallurgical vanadium extraction from slags of different chemical composition using soda technology; determination of the leaching mode effect (temperature and duration) on the vanadium extraction degree. Experimental samples in the form of slag and soda Na₂CO₃ mixture were processed to oxidative roasting and subsequent water leaching at different temperatures from 50 °C to 80 °C for 1, 2 and 3 hours. In the resulting solutions the vanadium content was determined with X-ray fluorescence spectroscopy (XRF). Analysis of the research results showed that the slag chemical composition and the water leaching conditions had a significant effect on vanadium extraction degree. The vanadium extraction degree from the JSC “EVRAZ NTMK” slag was 2 – 2.5 times higher than from the ITmk3 process slag after applying the same leaching modes. The highest degree of vanadium extraction was obtained after leaching at a temperature of 80 °C for 3 hours. These leaching modes increased the vanadium extraction degree from the JSC “EVRAZ NTMK” slag to 65 – 87%, and from the ITmk3 process slag to 31 – 33%.

Abstract: Malaysia has many potential mineral resources including some rare earth elements (REE) minerals such as monazite. REE play critical roles in the applications of advanced materials. Alkaline fusion was introduce to monazite to break the bonding between Light Rare Earth Elements (LREE) and phosphate. In this study, critical parameter such as fusion temperature (100 °C to 250 °C) and duration (1 to 4 hours) were studied. The results shows that it is possible to recover nearly 100% of Neodymium after 2 hours fusion at 150 °C. In the other hand, more than 99% of Cerium and Lanthanum were recovered after 3 hours fusion at similar temperature. By recover most of the element, expectantly high yield of single LREE can be achieved in the forthcoming.

Abstract: The possibility of sorption extraction of nickel from leaching solutions of oxidized nickel ores of the Buruktal deposit is considered. Ionite Lewatit TP220 with bis-picolylamine functional groups is effective for nickel recovery against the background of high iron contents. Lewatit TP220 is mechanically strong enough for use in the resin-in-pulp process. Nickel sorption with satisfactory performance occurs both in the variant of sorption leaching and extraction from clarified solutions. At sorption from the pulp, the capacity for nickel was 5.44 mg/g, for iron, 25.17 mg/g. The use of 20% sulfuric acid provides quantitative nickel desorption. To obtain a higher quality nickel-containing product, it is recommended to additionally purify the resulting eluates from iron.

Abstract: The article deals with the mechanism of transition of silicon to aluminate solutions in the process of leaching aluminum sinters in the production of alumina from nepheline. It was found that features of the transition in silica aluminate solutions by leaching cakes of various types relate to the structure of two-calcium silicate, and the dependence of reactions in the aluminate solution, its temperature and composition. A pattern has been established that determines the relationship between the SiO₂/Al₂O₃ ratio in the list and the concentration of silica in aluminate solutions after leaching.

Abstract: The paper provides a flow sheet of the phosphorus slag processing to produce precipitated silica (white soot). The process conditions for opening phosphorus slag at the I stage of leaching have been selected: the nitric acid concentration is 3.5 mol/dm³; the ratio S:L = 1:3.5; the temperature is 60 oС; and the process duration is 1 hour. The parameters of the white soot production II stage have been determined: the HNO₃ concentration is 6.5 mol/dm³; the ratio S:L = 1:3.5; the temperature is 50 oС; and the process duration is 1 hour. The temperature effect on the white soot structure and the specific surface have been established. At optimal process parameters, the white soot batches have been obtained with the main SiO₂ component content of 88.2 and 90.5 %, and a specific surface of 170 and 182 m²/g, respectively. The through recovery of silicon into a commercial product is 98.0 % of its initial content in slag.