Metallurgical Evaluation of the Leaching Behavior of Copper–Cobalt-bearing Ores by the Principal Component Analysis Approach: Case Study of the DRC Copperbelt Ore Deposits

Cobalt (III) is present in most of the minerals in the Congolese Copperbelt deposits. Its hydrometallurgical treatment requires to be reduced to Co²⁺, using a reducing agent. Using the Principal Component Analysis (PCA) approach, a 16 × 7 matrix was built to identify groups of ores/reducers with similar metallurgical performance. The study was based on the optimum values of reducing agents for the four selected minerals: 1.34, 0.33, 1.51, 0.25 g for Fe²⁺; 0.63, 0.51, 0.47, 0.24 g for Na₂S₂O₅; 0.37, 0.11, 0.34, 0.21 g for Fe; and 2.02, 0.07, 0.13, 0.16 g for Cu. These optima crossed with other variables retained, in particular, the Cu and Co yields, reducing agent consumption, Cu and Co solubilization, and redox potential at leaching completion were reduced to two main components F1 (41.38%) and F2 (31, 46%). It emerges from the application of Principal Component Analysis to the 16 × 7 matrix a correlation circle showing that the variables having a major influence on the solubilization of Co are the reducing agent consumption by Co (24.48%), the amount of reducing agent (20.14%), and the potential at reaction completion (18.61%). Homogeneous groups of ores/reducers with good performance quality (F1 + F2 = 72.84%) were identified. In all and from a performance perspective, the ores treated with Fe²⁺, Fe, and Cu gave satisfactory metallurgical results (> 95% yield). On the contrary, the use of Na₂S₂O₅ on all the deposits gave lower results (between 90% and 95% Co). Graphical Abstract: [Figure not available: see fulltext.].