Dr. Pratima Meshram
Dr. Pratima Meshram
Department of Metallurgical Engineering, IIT BHU, India
Almost no acidic leaching process in battery recycling results in selectivity of metal dissolution from the electrode material particularly of LIBs and NiMHs. After acid leaching, the recovery processes become more complex because of the presence of multi-metals like lithium, cobalt, nickel, rare earth elements and other metal ions in the solutions. Leaching of all the constituent metals poses an issue in formulating a simple process for their separation by solvent extraction and precipitation. The constituent metals in the spent batteries exist in various associations from which selective recovery becomes a challenge that can possibly be addressed by acid baking as the first step followed by leaching. Therefore, this work aims at sulfuric acid baking and water leaching of the spent electrode material with the purpose of operating the same at comparatively lower temperature than that of the alkali roasting processes, besides ensuring lower acid consumption compared to the direct sulfuric acid leaching. Sulfation or acid baking results in the transformation of prominent metals to sulfate form in presence of sulfuric acid thereby breaking the impervious layer making the material more active, which if discharged into water or low concentration of acid can result in selective leaching of some metals (in transformed matrix) to the bulk solution phases. With respect to LIB, first stage leaching of baked cathode material with water led to selective extraction of 78.6% Li, 80.4% Co in 60 min at 75 oC and 25% pulp density. The second stage reductive leaching was performed using inorganic acid mixture with sugar solubilising 67% Ni, 64.8% Mn in 45 min. The overall recovery of the metals was found to be 93.2% Li, 90.52% Co, 82.8% Ni, 77.7% Mn. In case of NiMH, leaching was performed in water for dissolution of different metals present in the sulfuric acid baked material yielding 91.6% Ni, 97.8% Co, 98.5% Fe and high recovery of REs (87% Ce, 96% Nd, 98.4% Sm, 95.5% Pr) in 2h at 75oC and 100g/L pulp density; recovery of La only being low (<69%) in first stage. The second stage leaching with weak acid and reductant led to complete recovery of Co and Mn. Both the process are aimed for a complete closed loop operation involving dismantling of batteries amicably and utilizing all loose segments, followed by complete recovery of metals as salts from electrode powder, leaving behind high value nano-sized graphite.
Dr. Pratima Meshram is Scientist in the Metal Extraction and Recycling Division of CSIR-National Metallurgical Laboratory (CSIR-NML), Jamshedpur, INDIA. She graduated in Metallurgical Engg. from Pt. Ravishankar Shukla University, Raipur and obtained her post graduate degree (M.Tech.) from Banaras Hindu University (IIT-BHU), Varanasi specialized in extractive metallurgy. She attained the Ph.D. degree in Metallurgical Engineering from Banaras Hindu University (IIT-BHU), Varanasi, in the research area of battery recycling. Dr. Meshram also served as Junior Manager at Rashtriya Ispat Nigam Limited (Vizag Steel). She later joined as Junior Scientist in the Metal Extraction and Forming Division of CSIR-NML in the area of hydrometallurgy and allied disciplines. She has been associated with various projects sponsored by Govt. of India and industries in the capacities of Project Leader and Team Member, in the areas hydrometallurgy, electrometallurgy, recycling and waste management (metal scraps, effluents, e-waste, etc). Dr. Meshram has published over 25 papers in SCI Journals and National/International Conferences. She has presented several papers in ORAL/POSTER category at various National and International Symposia/Colloquiums in India. She has received several awards namely, Best in-House Project of CSIR-NML (2011), MISHRA Award for Best Paper published (2016) in the area of Hydrometallurgy by Indian Institute of Mineral Engineers (INDIA); TAMOTIA Award for best Paper Presented (2017) in the area of Environmental Issues in Mineral processing by Indian Institute of Mineral Engineers (INDIA), etc. She is also associated as member of various National Professional Bodies (Indian Institute of Metals, Indian Institute of Minerals Engineers, Materials Research Society of India). She is currently working in the areas of secondaries recycling and utilization for base, strategic and rare earth extraction.