Resumo

MOCCIA PARADISI, Alberto; HERNANDEZ-PARDO, Diego; ARDILA SANTAMARIA, Nadia  e  DELVASTO, Pedro. Hydrometallurgical valorization of spent Ni-Cd batteries using organic acids as selective leaching agents. Ing. Desarro. [online]. 2023, vol.41, n.2, pp.1-.  Epub 01-Nov-2023. ISSN 0122-3461.  https://doi.org/10.14482/inde.41.02.547.256.

In this paper, we propose a hydrometallurgical procedure to treat spent Ni-Cd batteries using organic acids as leaching agents. The electrode materials of the batteries were extracted and leached using a combination of acetic, citric, and sulfuric acids and their mixtures in a two-stage selective scheme. This procedure aimed to recover metal-bearing solid products. The leachates were treated by evaporation/crystallization or chemical precipitation to obtain the solid products. These products were characterized using scanning electron microscopy, chemical analysis by atomic absorption spectroscopy, mineralogical phases by x-ray diffraction, and infrared spectroscopy. In the first leaching step, 15 % m/m citric acid was used to recover 85±5 wt.% of the cadmium present as a carboxylate salt. In the second leaching stage (5 % m/m acetic acid mixed with 3 % m/m sulfuric acid), 50±3 wt.% of nickel was recovered, in the form of a product consisting of a mixture of hydroxides and salts. The remaining solid from the second leaching stage was a valuable metal product containing nickel (96±4 wt.%). The analysis of the results allowed us to depict a conceptual process flow diagram for the selective leaching of the spent Ni-Cd batteries, and the possible industrial use of the solid products obtained.

Palavras-chave : hydrometallurgy; organic acids; spent Ni-Cd batteries; valorization.

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