Papers by Keyword: Olivine

Abstract: The raw materials of stainless steel production are mainly derived from nickel laterite ore. The production of stainless steel is carried out using the pyrometallurgical method. The Rotary Kiln Electric Furnace (RKEF) process is widely used to produce ferronickel or nickel matte. The feed for the RKEF smelter originates from saprolite ores and is usually divided into soft saprolite and rocky saprolite. Soft saprolite generally has a higher Ni-grade than rocky saprolite. The potential for increased nickel grade in rocky saprolite can be carried out by screening the bulk ores to minimize gangue materials. In this study, a total of 22 samples of saprolite ore were taken from five different mining fronts and then screened to produce a series of fractions with the size of -2", +2"-4", +4"-6", +6"-8", + 8”. Results of chemical analysis using the XRF method show that enrichment of Ni was found in the -2” fractions, and Ni grade tends to decrease with the larger fraction sizes. Lizardite is the principal nickel-hosted mineral in saprolite ores with the highest composition in the cumulative fraction -2”. Gangue minerals, mainly olivine, significantly affect the enrichment of Ni, especially in the coarser fraction. The higher olivine composition indicates a lower Ni content. The (+6-8)" and (+8)" fractions should be removed to obtain the optimum Ni grade and recovery.

Abstract: Li ion battery or LIB is an energy storage device that provides and store electrical energy and chemical energy, respectively. LIBs have been widely developed in the energy sector owing to their considerable high energy density, high capacity, and long-life cycle. In this study, the LiFePO₄/C cathode was synthesized from various precursors FeC₂O₄, FePO₄, Fe₃(PO₄)₂, Fe₂O₃ obtained via co-precipitation method, and continued with solid-state. The effects of precursors were studied in this study. The precursor and the resulting product were analyzed using XRD, FTIR, SEM, and EDX, while the electrochemical performance was tested using charge-discharge, cycle stability and rate capability. All precursors were successfully synthesized as evidenced by XRD, FTIR, SEM, and EDX characterization tests. Based on electrochemical performance test, the highest capacity that can be achieved is 109 mAh/g obtained from LFP with FeC₂O₄ precursor, with a reduction in capacity of 54.7% after 50 cycles.

Abstract: The synthesis of LiFeSi_0.03P_0.97O₄/C (LFSP/C) composites have been done by solid state method. This study investigates the effects of carbon coating on the structure, microstructure and electrical conductivity of LFSP/C cathode materials. The carbon coating on Lithium Ferro Phosphate (LFP) plays a crucial role in determining its electrical conductivity. The variation of carbon content is 0wt.%; 6wt.%; 7wt.%; 8wt.% (LFP-0%, LFP-6%, LFP-7% and LFP-8%). The characterization was performed using X-Ray Diffraction (XRD), Scanning Electron Microscopy - Energy Dispersive X-ray (SEM-EDX), HighResolution-Transmission Electron Microscopy (HR-TEM) and LCR Meter tests. The XRD result have shown single-phase olivine (LiFePO₄) in all samples. The analysis microstructure using SEM have shown increasing carbon content can reduce agglomeration. The particles size of LFSP is 845.570 nm, and after coating carbon the particles size decreased up to 457.191 nm. The EDX results showed that the amount of atomic percentage for carbon tends to increase as the amount of carbon content increased. HR-TEM images indicates that the formation of carbon layer have formed, but not perfectly coat the LFP particle. The average carbon layer size is 78,31 nm with the size of LFSP particle is 352.82 nm. The LCR Meter result showed that LFP-7% had the largest electronic conductivity (2,275x10^-7 S/cm). The carbon coating led to significant enhancement in electronic conductivity from ~10^-9-10^-10 S/cm to ~10^-7 S/cm.

Abstract: This research study about the influence of carbon concenttration as coating on electrical conductivity of LiFeSi_0.03P_0.97O₄/C. Synthesis of LiFeSi_0.03P_0.97O₄/C was carried out different carbon concentrations of 7, 9, and 11 wt%. The raw materials used are Fe₂O₃, Li₂CO₃, (NH₄)₂HPO₄, SiO₂ as ion Si doping, and glucose as carbon sources. The XRD analysis results showed that all the diffraction peaks in samples were the olivine LiFePO₄ phase. From the EIS result, Samples with the addition carbon concentration of 9 wt% produce the highest electrical conductivity values of 4.18 x 10^-7 S/cm.

Abstract: LiFeSi_0.03P_0.97O₄/C composite materials with variations in duration of milling are 4, 8, 12, and 16 h have been synthesized successfully by solid-state process. The iron stone from Tanah Laut Kalimantan used as source of ion Fe and Glucose used as material coating. The result of XRD have shown all of the samples have a olivine LiFePO₄ phase except for milling 16 h. The largest electrical conductivity was 1.75x10^-8 S/cm observed in sample of 16 h.

Abstract: Phase pure olivine LiNiPO₄ and doped LiNi_0.8Mn_0.1Co_0.1PO₄ powders have been prepared by conventional solid state route. X-ray diffraction (XRD) combined with Rietveld refinements analysis reveals the formation of LiNiPO₄ and doped LiNi_0.8Mn_0.1Co_0.1PO₄ with high crystalline nature at high temperature of 950 °C and 1000 °C. The lattice parameters of doped LiNi_0.8Mn_0.1Co_0.1PO₄ are significantly larger than LiNiPO₄. It has been found out that the estimated crystallite size is in the order of nanometres for both samples. SEM analysis confirms that the particles have connected with each other in random shape and sub-microns size. The particle size has increased as small amount of Mn and Co are doped into LiNiPO₄. The AC impedance spectroscopy measurements have revealed that the conductivity of LiNiPO₄ is enhanced by around one order of magnitude by doping Mn and Co.

Abstract: In this article, we analyzed connection between development of grain misorientation of different olivine fabrics from dunites of the Tarlashkinsk Massif (SE Tuva, Central Sibiria) and their geometrical parameters (grain size, specific area of grain boundaries, volume fraction of large and small components). Crystallographic orientation of olivine fabric types was also analyzed. It was indicated that bimodality in grain sizes disappears while changing into mosaic type. It was obtained by the EBSD method that the grain orientation changes starting with porphyroclastic type, and maximum scattering of olivine grain misorientations is observed when forming mosaic fabric. The results obtained confirm a hypothesis stipulated by authors earlier about deformation transformations of olivine as a result of geological processes during the obduction of mantle ultrabasites.

Abstract: This study investigated the improving catalytic effects during tar catalytic reforming by impregnated NiO and CeO₂ onto olivine, and the further reduction of carbon deposition on the catalysts was achieving by the addition of MgO. A series of characters of the catalysts were tested by XRD, TPR and TPD. The experimental results showed the addition of MgO could improve the resistance to carbon deposition and had demonstrated higher reaction activity at higher temperature and lower water-carbon ratio. The activities of catalysts were not only related to the impregnating order of the promoters NiO and CeO₂ but also to the water (steam)-carbon ratio (S/C). Those catalysts impregnated Mg, Ce and Ni in order could achieve highly disperse sites and further promote the interaction between active sites and carriers. Furthermore, those catalysts also had higher reaction activity and better anti-coking abilities under low water (steam)-carbon ratios.

Abstract: The LiFePO₄ nanoparticles with high crystallinity were prepared using polyol process without any further heating as a post step, which will greatly economize in time and energy comparing with other conventional synthesis method. The temperature of the polyol solution was rapidly increased up to 550 K and maintained for 24 h in a round-bottomed flask attached to refluxing condenser to obtain nanoparticles. The X-ray diffraction (XRD) pattern was indexed on the basis of orthorhombic olivine-type structure without any unwanted second phase. The scanning electron microscopy (SEM) images of the samples showed the needled and flaky shapes of particles with uniform size in the range of 50-250 nm. It is noted that the nanoparticle was in favor of shortening the diffusion path to improve electrochemical performance. A reversible specific capacity around 160 mAh·g^-1 at 0.1C rate was achieved without capacity fading during the 20 cycles.

Abstract: Currently solid wastes generated from manufacturing process of thermosetting composite have caused environmental problems because they are non biodegradable product and cannot be recycled or remolded due to chemically crosslinked. Thus, the aim of this research is to convert glass fiber reinforced epoxy composite waste to fuel gases by gasification process. The composite waste was first grounded and its thermal decomposition behavior was then investigated using isothermal thermogravimetric analysis (TGA) from an ambient to 900°C at heating rate of 10°C/min under nitrogen atmosphere. The results showed that major decomposition temperatures of the epoxy matrix were ranging from 300 to 450°C. The composite sample was then mixed with two different catalysts, olivine (LiFePO₄) or 10%NiAl₂O₃ in order to study the effect of catalyst on gas conversion efficiency before it was gasified in a fixed bed reactor at final temperature of 500, 600, 700, and 800°C under nitrogen mixed with air at total flow rate of 200 mL/min. Gasification process indicated that solid residues were mainly brittle black containing residual glass fiber. The significant increasing of carbon monoxide and carbon dioxide conversion was achieved from sample mixed with olivine catalyst at gasification temperature of 700°C, when compared with result without catalyst at baseline conversion of 500°C as. Therefore, it can be expected that gasification process is a promising method to deal with epoxy composite for producing renewable energy.