BR-102024017592-A2 - SUSTAINABLE PROCESS FOR OBTAINING CERIUM HYDROXIDE AND LANTHANUM OXALATE FROM WASTE NICKEL METAL HYDRIDE BATTERIES

Abstract

The present invention consists of a sustainable process for obtaining cerium(IV) hydroxide, with 99.6% purity, and lanthanum oxalate, with 99.7% purity, from nickel-metal hydride battery (NMH) waste. In this process, the NMH batteries are initially discharged, dismantled, and the active anode material (OM) is separated from the other parts. After separation, the OM is subjected to an acid dissolution step, obtaining a leachate. The leachate obtained is mixed with a eutectic solvent (HES), obtaining a biphasic system. Controlling the proportion between the phases of this biphasic system, the concentration and nature of the acid used in the leaching step, and the composition of the HES, allows for the selective and complete extraction of the lanthanides, which are subsequently precipitated separately under specific conditions. The recycling and reuse of HES is carried out without affecting the recovery of lanthanides or the separation selectivity, increasing the environmental compatibility of this process. This hydrometallurgical process stands out for its environmental and economic prospects, sustainably recovering critical raw materials from a secondary source using a green solvent with minimal separation steps, which is applicable to the mining sector.

Inventors

• MARIA DO CARMO HESPANHOL
• KAÍQUE AUGUSTO MOREIRA LOURENÇO CRUZ

Assignees

• Universidade Federal de Viçosa

Dates

Publication Date

20260310

Application Date

20240827

Claims (2)

1. 1) Process for obtaining cerium hydroxide and lanthanum oxalate from nickel-metal hydride battery waste, characterized by comprising the following steps: • Obtaining nickel-metal hydride batteries from electronic waste; followed by their discharge, dismantling and collection of the active material from the anode and cathode in the form of a black paste; • Washing the obtained paste, drying the paste and macerating it until obtaining the black powder, BM; • Dissolving the BM in nitric acid solution for 2 to 3 hours, under stirring, at a temperature between 85 and 95°C; • Obtaining the liquor rich in transition metals, cerium and lanthanum; • Mix, under stirring, the obtained liquor and the hydrophobic eutectic solvent, C24H51OP:C10H20O2, saturated with HNO3, in mass proportions of 1:1 to 1:8 liquor/solvent, stir and let stand until a two-phase system is observed; • Perform liquid-liquid separation and obtain the hydrophobic eutectic phase, FE-E; • Mix HCl solution with FE-E and let stand until a two-phase system is observed; • Obtain, by separation, the FE-S and FA-S phases; • Adjust the pH of FA-S to a value between 4.5 and 5.5 and add hydrogen peroxide solution (30%), adjust the pH to 3.30 and perform solid-liquid separation; • Obtain, from the solid-liquid separation, solid cerium (IV) hydroxide, FS-Ce, and the aqueous phase FA-La; • Dry the obtained solid FS-Ce; • Add 1:40 (w/w) oxalic acid to the obtained aqueous phase, FA-La, and perform solid-liquid separation; • Obtain lanthanum(III) oxalate, FS-La, and aqueous phase from the solid-liquid separation; • Dry the obtained solid FS-La; • Optionally, regenerate the hydrophobic eutectic phase from the aqueous phase FE-S.
2. 2) Process for obtaining cerium hydroxide and lanthanum oxalate from nickel-metal hydride battery waste, according to claim 1, characterized in that the hydrophobic eutectic mixture, C24H51OP:C10H20O2, is obtained from a mixture of trioctylphosphine oxide and decanoic acid, at a molar ratio of 1:1.

Description

TECHNICAL FIELD OF THE INVENTION 1. The present invention consists of a sustainable process for obtaining cerium hydroxide and lanthanum oxalate from nickel-metal hydride battery (NMHNB) waste. In this process, NMHNBs are initially discharged, dismantled, and the active anode material (BM) is separated from the other parts. After separation, the BM is subjected to an acid dissolution step, obtaining a metal-rich solution (leachate), including the lanthanides lanthanum and cerium, whose separation followed by the obtaining of pure compounds of these lanthanides is proposed. The leachate obtained is mixed with a eutectic mixture (HES), obtaining a biphasic system. The control of some parameters, such as the proportion between the phases of this biphasic system, concentration and nature of the acid used in the leaching step, and composition of the HES, allows the selective and complete extraction of the lanthanides, which are subsequently precipitated separately under specific conditions. The recycling and reuse of HES is carried out without affecting the recovery of lanthanides or the separation selectivity, increasing the environmental compatibility of this process. This hydrometallurgical process stands out for its environmental and economic prospects, sustainably recovering critical raw materials from a secondary source using a green solvent with minimal separation steps, which is applicable to the mining sector. STATE OF THE ART 2. Lanthanides, such as cerium (Ce) and lanthanum (La), are essential in the automotive, aerospace, defense, medical, and other industries (Lie, J., Lin, Y. C., & Liu, J. C. Process intensification for valuable metals leaching from spent NiMH batteries. Chemical Engineering and Processing - Process Intensification, 2021, 167, 108507). Due to the high demand and economic importance of lanthanides, some countries that do not possess primary resources of these elements are subject to supply restrictions due to monopolies held by countries such as China, which is responsible for supplying more than 90% of the lanthanides consumed worldwide. Therefore, it is of paramount importance that countries unable to obtain lanthanides from primary resources develop appropriate technology to recover lanthanides from electronic waste in order to meet the high demand for these metals in the domestic market. 3. Lanthanides have been classified as critical raw materials (CRMs) by the European Union (European Commission, Communication from the Commission to the European Parliament, the Council, Critical Raw Materials Resilience: Charting a Path towards greater Security and Sustainability, 2022). Seeking to mitigate the scarcity of CRMs in countries that are not favored with economically viable primary Ln resource deposits, urban mining has been investigated as a promising emerging solution. The consolidation of urban mining contributes to sustainable development, as recycling becomes a key point (Lu, Y., Han, X., & Li, Z. Enabling intelligent recovery of critical materials from li-ion battery through direct recycling process with internet-of-things. Materials, 2021, 14(23),7153) so that CRMs present in post-consumer materials, mainly electronic waste (e-waste), are inserted into the production chain, reducing the need for CRM imports. Among the various types of e-waste, nickel-metal hydride batteries (NIMH batteries) deserve special mention, proving to be a promising source of CRM. The active material of these batteries (cathode plus anode) is composed on average of 36-42, 25, 4 and 8-10% (w/w) of Ni, Fe, Co and lanthanides, respectively (Ebin, B., Petranikova, M., & Ekberg, C. Physical separation, mechanical enrichment and recycling-oriented characterization of spent NiMH batteries. Journal of Material Cycles and Waste Management, 2018, 20(4), 2018-2027). 4. In the literature, different processes are reported to recycle metals from BNiMH dividing into i) Pyrometallurgical process (Maroufi, S., Nekouei, R. K., Hossain, R., Assefi, M., & Sahajwalla, V. Recovery of Rare Earth (i.e., La, Ce, Nd, and Pr) Oxides from End-of-Life Ni-MH Battery via Thermal Isolation. ACS Sustainable Chemistry & Engineering, 2018, 6(9), 11811-11818; Jiang, Y. Ju, Deng, Y. Chun, & Bu, W. gang. 21532157; Tang, K., Ciftja, A., van der Eijk, C., Wilson, S., & Tranell, G. Recycling of the rare earth oxides from spent rechargeable batteries using waste metallurgical slags. Journal of Mining and Metallurgy, Section B:Metallurgy, 2013, 49(2), 233-236; patent documents US7169206; US7169206; Inmetco industrial process; Snam industrial process; Mond Proces industrial process); ii) Pyrometallurgical and hydrometallurgical (UMICORE industrial process); iii) Mechanical process (patent documents US8246717; US8696788, US8246717); iv) Mechanical and thermal process (patent document DE19727880); v) Hydrometallurgical process (Lie, J., Lin, Y. C., & Liu, J. C. Process intensification for valuable metals leaching from spent NiMH batteries. Chemi