The loss pathways of Ni and Co during Al and Sc enrichment were analyzed in the HNO₃ leach liquor of saprolitic laterite ore. Although over 99% of Al and Sc can be enriched, about 40% of Ni and Co are also lost. The adsorption of Al−Sc precipitate is an important cause of Ni and Co loss. Subsequently, the precipitation behavior of metal ions in the different nitrate solutions was studied. The results confirm that Ni²⁺ and Co²⁺ do not hydrolyze to form their respective hydroxides. Ni²⁺, Co²⁺ and Mg²⁺ can form composite hydroxides with precipitated Al(OH)₃, decreasing the pH at which Ni²⁺ and Co²⁺ begin to precipitate, causing their co-precipitation loss. A high Mg²⁺ concentration enhances the formation of these composite hydroxides. Finally, titration curves for different nitrate systems were determined, further demonstrating the formation of Me−Al composite hydroxides and revealing a formation trend of Mg−Al > Co−Al > Ni−Al.