Numerous upcoming high-pressure acid leaching (HPAL) projects aim to generate secondary nickel products, such as mixed-hydroxide precipitate (MHP), to facilitate lithium-ion battery manufacture, owing to their reduced energy intensity and lower CO2 emissions. While elevated feed loading enhances throughput in single-line MHP production, it may negatively impact slurry mixing, handle ability, pump performance, and promote scale formation. This research examines variables affecting slurry properties, including ore mineralogy, particle size, and solid concentration. The Taguchi approach is employed to identify the optimal levels of each parameter, while Grey Relational Analysis (GRA) is utilized to optimize the multi-response of %Ni extraction and yield stress. The corresponding levels of each factor are as follows: BDM, HJY, and KNN for ore type; below 50 mesh, 100 mesh, and 200 mesh for particle size; and 30, 35, and 40 pct for solid concentration. In this study, the optimal process conditions are KNN ore, a particle size below 200 mesh, and 30 pct solid concentration. Based on the analysis of variance (ANOVA) of Grey relational grade (GRG) values, the solid concentration is the most influential factor followed by ore type and particle size, with the pct contribution value of 79.133, 0.053, and 4.667 pct, respectively.
