LEACHING OF LATERITE NICKEL ORE USING ORGANIC ACIDS

• DOI: https://doi.org/10.22533/at.ed.973412402013

• Palavras-chave: Laterite ore; Leaching; Citric acid; Filamentous fungi.

• Keywords: Laterite ore; Leaching; Citric acid; Filamentous fungi.

• Abstract:

  Organic acids are easier to handle, biodegradable, do not emit harmful gases into the atmosphere and are less corrosive than inorganic acids. For these reasons, they are called green leachants. Citric acid proved to be the most appropriate organic acid for leaching nickel and cobalt from saprolite ores, having the advantage of being more selective for iron and magnesium compared to sulfuric acid, frequently used in industry. This study aims to identify strains of filamentous fungi that produce citric acid for subsequent production in submerged environments and verify the recovery of Ni and Co contained in laterite ores. Preliminary experiments to select filamentous fungi with greater citric acid production potential were carried out using Foster's medium, with three Aspergillus strains being selected. Simultaneously, atmospheric leaching tests were performed using an incubator shaker, citric and lactic acids. The best nickel and cobalt recovery results, of 81.59% and 84.54%, respectively, were obtained using saprolite ore and citric acid. Due to the fact that nickel is associated with goethite in limonite ore, its recovery was only 27.03%, since, under the conditions used, it was not possible to break the goethite crystal lattice.