Leaching of exhausted LNCM cathode batteries in ascorbic acid lixiviant: a green recycling approach, reaction kinetics and process mechanism

Abstract

BACKGROUNDCritical metals (lithium, cobalt and nickel) used in Li‐ion batteries have been estimated to face a supply crunch by the end of 2020 due to their limited natural reserves and complex metallurgy. A green recycling approach to treat the exhausted batteries may potentially mitigate supply risks of metals and environmental burden of metal toxicity.RESULTSThe maiden application of bio‐producible/degradable ascorbic acid for the leaching of LiNi xCo yMn zO2 (LNCM) cathode batteries was investigated while performing parametric variations. Inhibited leaching at high temperature and long contact time showed the adversity caused by the possible decomposition of ascorbic acid. The low leaching of cobalt as a function of acid concentration indicated the hindrance in dissolution of Co(III) compound. A quantitative leaching of metals (≥96%) could be achieved under the following optimal conditions: agitation speed, 500 rpm; acid concentration, 2.0 mol L−1; temperature, 75 °C; time, 90 min; and pulp density, 6%. The apparent activation energy of metals was calculated to be more than 40 kJ mol−1.CONCLUSIONAscorbic acid could potentially dissolve the cathode material without introducing any additional reducing agent into the system. The leaching kinetics fitted with an empirical model {−ln(1 − x)}2 versus t could reveal that the overall dissolution process follows a chemically controlled mechanism. The present study leads towards sustainable metallurgy using a biodegradable reagent instead of applying harsh and hazardous mineral acids. © 2020 Society of Chemical Industry

Recovery of Platinum-Group Metals from an Unconventional Source of Catalytic Converter Using Pressure Cyanide Leaching and Ionic Liquid Extraction

“…This change in the PGM dissolution behavior indicates a change in the rate mechanism from diffusion-controlled at low cyanide concentration to the chemically-controlled at higher cyanide in solution. 11 , 30 , 31 The maximum leaching efficiency (Pt, 157.5 mg/L; Pd, 77.6 mg/L; and Rh, 33.9 mg/L) was achieved at 5.82 g/L NaCN solution captured through the microbial-driven HCN synthesis. Thus, this concentration was consider optimum to generate the stock leach liquor for subsequent recovery studies using an ionic liquid (Cyphos IL101).…”

“…An increasing trend of metal dissolution can be ascribed to the physical phenomenon of increased collisions between the particles of the heterogeneous system. 30 , 31 Dissolution efficiency reached the maximum of 91% Pt, 94% Pd, and 87% Rh at 150°C; thereafter, increasing temperature showed a decline in PGM dissolution (87% Pt, 81% Pd, and 84% Rh at 150°C). Comparatively, Pt and Rh dissolution decreased slightly in contrast to a steep decline of Pd, which can be corroborated by the non-stability of Pd(CN) 4 2− and by cyanide decomposition at higher temperatures.…”

Mobilization of platinum and palladium from exhausted catalytic converters using bio-cyanide and an ionic-liquid as mass transport carriers

“…3.2.4 Kinetics and mechanism. To further elucidate a mathematical description of the pressure leaching process, the kinetics of the heterogeneous reaction was investigated using the commonly employed shrinking core model for spherical particles using the eqn (10) and (11): 44,45 1 -ð1 -…”

Hydrometallurgical Production of Electrolytic Manganese Dioxide (EMD) from Furnace Fines

“…Figure 7a shows the effect of current density on current efficiency in a 0.25 M H 2 SO 4 containing electrolyte. The current efficiency (CE) of the process is calculated based on Equation (6), where W, n, F, M, I, and t refers to the weight of MnO 2 deposited, the number of electrons, the Faraday constant (96500 coulombs), the molecular weight of MnO 2 , the current in amperes (amps), and time in seconds, respectively.…”

“…The most important use of MnO 2 is in primary Leclanché (carbon-zinc) and alkaline batteries. This material is used in obtaining the spinel structure of the cathode materials to be used in rechargeable Li-ion batteries (e.g., LiMn 2 O 4 ) [4][5][6]. MnO 2 needed for the production of batteries must have high purity and high electrochemical activity.…”