ANALYSE DES ETAPES DES PRECIPITATIONS ET PURIFICATION DU COBALT A PARTIR D’UNE SOLUTION DE LOW GRA DE RAFF « Cas de l’usine 15K de tenke fungurume mining »

The objective of this work is to optimize the precipitation and purification parameters of cobalt in the form of hydroxide in the TFM 15k plant. Indeed, the extraction of cobalt, presents a great challenge in TFM factories due to a poor yield of cobalt recovery and a low purity related to the presence of impurities The methodical approach allowed us to carry out tests by varying 3 key parameters, namely: pH, stay time and agitation speed. We carried out 4 series of tests including 3 according to the parameters mentioned above and a fourth series by considering a seeding of the filtra with the cake from secondary decobalting in order to improve the purity of the cobalt hydroxides produced in primary decobalting which are even commercial hydroxides. The sample solution has the following chemical characteristics: 1.78g/l Co, 0.845g/l Cu, 0.49g/l Mn, 0.88g/l Ca, 4.9 g/l Mg, 0.323g/l Al, 1.19g/l Fe, 0.42g/lNa, 0.26g/l Si and 0.04g/l Zn The results obtained showed that: for the purification stage, it is better to work according to parameters such as a final pH of 3.8, a stay time of 4h and an agitation of 700 rpm allow a removal of 96.34% of iron and 97.5% of aluminum compared to the current values of the factory which are 89.9% for Iron and 76.28% for aluminum; for the decomification stage, it is better to work with the parameters such as a final pH of 5.8, a stay time of 4h and an agitation of 500 rpm for an elimination of 97.96% of the copper contained in solution and a low co-precipitation of cobalt or 1.9% of the total amount present in solution; for decobaltage, the optimum parameters found in the primary is a pH of 7.8, a stay time of 4h and an agitation of 500 rpm for a purity of cobalt hydroxides of 38.2% and a recovery of 70%, for secondary decobalting pH of 8.6 a stay time of 4h and an agitation of 300 rpm pushes the recovery yield to a value of 85.42% or an improvement of 15.42% compared to That of the primary; as for the seeding of the primary decobaltage by the secondary cake, it has been held that with a quantity of 4g of cobalt hydroxide in a solution of 1l, we can have a purity of 42.01%, an improvement of 3.81%.