Wewegedara, W.G.C.N.Amaraweera, T.H.N.G.Wijayasinghe, H.W.M.A.C.2022-03-112022-03-112013http://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/8487/25-MRT-Purification%20of%20Vein%20Graphite%20by%20Alkali%20Roasting%20for%20Anode%20Material%20in%20Lithium%20.pdf?sequence=1&isAllowed=yUnique vein graphite deposits with highly crystallized and high purity graphite are present in the mineralization zone of the central highlands of Sri Lanka This graphite has been identified as a potential candidate for the lithium ion rechargeable batteries (Balasooriyaet al., 2007). Recent attention has been made towards the purification of vein graphite in order to prevent the anode ageing and decomposition of the electrolyte in lithium ion batteries (Amaraweera et al., 2013). Alkali roasting for purification of graphite has found to be a very effective method to remove sulfide and silicate impurities at low temperatures (Lu et al., 2002). Therefore, this study focused on studying the effectiveness of alkali roasting for the purification of vein graphite in Sri Lanka Methodology Graphite powder (<53 µm) from Needle Platy Graphite (NPG) and Shiny Slippery Fibrous (SSF) morphological types from Bogala and Kahatagaha mines were used for this study. The graphite was treated in aqueous solutions containing 5, 10, 15, 20, 25, 30 and 35 vol. % NaOH (Solid: liquid, 1:2) separately and roasted at 250 C under air for one hour. Then, the roasted sample was acid leached in 10 vol. % H2SO4. After that, the solid was filtered, washed to neutral and vacuum dried at 100 C for 15 hours. Minimum concentrations of NaOH for the purity enhancement were identified for each graphite type. Roasting treatments were repeated at 150 C, 200 C, and 300 C, using the data obtained previously to identify the effect of roasting temperature on purity enhancement. Carbon percentages of the treated graphite samples and untreated graphite samples were determined by heat treating at 950 C for 3 hours in Muffle Furnace, according to ASTM – C 561 and weighing the residues. Pellets of treated and untreated graphite powder (D =12 mm and L = 5 mm) prepared by cold uniaxial pressing at 100 Mpa were used to measure D.C conductivity by four-probe method at room temperature.enScience and TechnologyMineral SciencesMaterials SciencesGraphite IndustryGraphiteOther