Bayesian statistics study of a sustainable dissolution of cobalt‐bearing minerals from Cu‐Co ores

Abstract

The present paper discusses the dissolution of cobalt‐bearing minerals from a copper‐cobalt ore using probabilistic models where a priori and a posteriori knowledge of leaching are used to predict the dissolution of cobalt‐bearing minerals in a sulphuric acid medium in the presence of a reducing agent. Priorly, the dissolution of cobalt‐bearing minerals depends on their mineralogy, leading to the use of FeSO4 as a reducing agent for the trivalent (Co3+) form of cobalt (CoOOH). A posteriori, the dissolution of Co3+ is improved by the presence of ferrous ions, resulting from the dissolution of Fe‐bearing minerals, including Fe from Co(Fe)OOH. The results showed that the predictive‐oriented probabilistic graphic models based on the Bayesian approach, in combination with the design of the experiment data, made it possible to model the leaching of cobalt‐bearing minerals. The results from the design of the experiment using the experimental tree methodology associated with the optimization of the multiple responses in a multiple input for a multiple output set‐up derived the following optimized parameters: 60°C for the temperature (T), 850 rpm for the agitation, 40% for the solid percentage, 1.5 for the pH, and 4 g/L for the concentration of the Fe2+ ion. The cobalt dissolution yield obtained was 89.95%. The analysis of the dependence between the random variables only (P(Fe2+|T), P(pH|T), and P(Fe2+|pH)) and the dependence between the random variables and the responses (P(Co‐yield|pH, Eh)) allowed the construction of two Bayesian networks, respectively, with and without posterior knowledge. For the Bayesian network with posteriori knowledge, the {5–2} structure was found to be the most appropriate arrangement. The model predicted a cobalt yield value, and the experimental value indicated a correlation coefficient (R2) of 0.861.

Supervised Training and Unsupervised Machine Learning Testing for Cobalt Dissolution from Complex Cu-Co Ores in Acid Lixiviants

“…The major or main cobalt sulphide ore is carrolite (CuCo 2 S 4 ) which is processed through flotation and with the cobalt oxide ore, the main sources are asbolane (CoO) ((Ni,Co) 2− ×Mn 4+ (O,OH) 4 nH 2 O), smaltite (CoAs 2 ), and heterogenite (when crystallized forms to stainierite Co 2 O 3 .H 2 O or CoO. 2 Co 2 O 3 .6H 2 O in an amorphous form) [7]. It is recorded that these ores require specific conditions to achieve an optimum dissolution, these require the presence of reducing agents or strong leaching acids.…”

“…Analysis shows that the main mineral of cobalt, heterogenite for this case, contains Co (II) and Co (III). Moreover, the difficulty lies within the treatability of these forms of cobalt, Co (II) is said to be easy to treat whereas Co (II) has some difficulties with regards to its treatment [7]. Therefore, the need to use reducing agents is prevalent to increase the solubility of cobalt [11].…”