The primary pathways by which nickel (Ni) and cobalt (Co) loss could occur from acidic sulfate solution during partial neutralisation of synthetic nickel laterite pressure acid leach solutions (to pH 4 at 85 °C) was investigated. Knowledge of the avenues by which Ni and Co loss occurs will enable minimisation of valuable metal losses through optimisation of the partial neutralisation process. Precipitation of Ni and Co as their hydroxides did not appear to be a pathway by which metal loss occurred during partial neutralisation. Additionally, co-precipitation of Ni and Co with either Fe(III) or Al was not found to be significant route for valuable metal loss. Adsorption onto freshly precipitated hydrous oxides of Al and Fe(III), as well as haematite, a major component of nickel laterite pressure leach discharge solids, appeared to be the primary route by which Ni and Co loss occurs during partial neutralisation. There was a preference for Co to adsorb onto haematite and ferric iron precipitates whilst Ni preferentially adsorbed onto Al precipitates. The molar ratio of Al to Fe(III) in the synthetic feed liquor was found to be a key variable controlling Ni and Co loss during partial neutralisation. Final Ni losses initially increased with increasing Al/Fe molar ratio in the feed, being at their highest in the absence of Fe(III) (10.7% Ni loss), and when the Al/Fe molar ratio in solution was unity (11.9% Ni loss), then decreased significantly when the Al/Fe ratio in the feed liquor was greater than or equal to 2 (2% Ni loss). Cobalt losses generally decreased with increasing Al/Fe ratio in solution except for in the presence of haematite where Co losses were 3.30%, confirming that Co adsorption onto haematite is a significant route by which loss of this valuable metal occurs during partial neutralisation.

研究了在部分中和合成镍红土加压酸浸溶液（在85°C下达到pH 4）期间，硫酸盐溶液中镍（Ni）和钴（Co）损失可能发生的主要途径。知道发生Ni和Co损失的途径将通过优化部分中和过程使有价值的金属损失最小化。Ni和Co的氢氧化物的沉淀似乎不是在部分中和过程中发生金属损失的途径。另外，未发现Ni和Co与Fe（III）或Al的共沉淀是造成有价值的金属损失的重要途径。吸附在新沉淀的Al和Fe（III）的水合氧化物以及赤铁矿上，赤铁矿是镍红土加压浸出固体的主要成分，看来是部分中和过程中发生Ni和Co损失的主要途径。Co优选吸附在赤铁矿和三价铁沉淀上，而Ni优选吸附在Al沉淀上。发现在合成进料液中Al与Fe（III）的摩尔比是控制部分中和过程中Ni和Co损失的关键变量。最终镍的损失最初随着进料中Al / Fe摩尔比的增加而增加，在没有Fe（III）的情况下达到最高（Ni损失为10.7％），并且当溶液中的Al / Fe摩尔比统一时（11.9％）镍损失），然后当进料液中的铝/铁比大于或等于2（镍损失2％）时显着下降。钴损失通常随着溶液中Al / Fe比的增加而降低，除了存在赤铁矿时Co损失为3的钴。