[ Utilisation du calcaire comme agent précipitant des impuretés des solutions cobaltifères des usines de Ruashi Mining en R.D.C. ]
Volume 32, Issue 2, March 2021, Pages 220–229
L. Zeka1, A. Kafat2, F. Manene3, and A. Ilunga4
1 Département de Chimie Industrielle, Faculté Polytechnique, Université de Lubumbashi, B.P. 1825, Lubumbashi, RD Congo
2 Département de Métallurgie, Faculté Polytechnique, Université de Likasi, B.P. 1946, Likasi, RD Congo
3 Département de Chimie Industrielle, Faculté Polytechnique, Université de Lubumbashi, B.P. 1825, Lubumbashi, RD Congo
4 Département de Chimie Industrielle, Faculté Polytechnique, Université de Lubumbashi, B.P. 1825, Lubumbashi, RD Congo
Original language: French
Copyright © 2021 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The possibility of using limestone instead of lime as an agent precipitating impurities from cobalt-rich solutions from the hydrometallurgical plants of Ruashi Mining in R.D. Congo was studied. These solutions come from the copper solvent extraction circuit and are intended for the production of cobalt hydrates. Precipitation tests performed in the laboratory have shown that limestone competes with lime in terms of precipitation of Fe, Mn and Cu impurities and co-precipitation of Co. The parameters which were exploited are: Eh, pH, time, % Solid and the particle size. Reduced to the equivalent quantities which enter into a precipitation reaction with 1.5 as the evaluated value of the limestone/lime ratio, the consumption of these two precipitating agents is almost the same. Co-precipitation of cobalt was acceptable and was limited to a yield of 3.0 % Co. Under these same conditions, copper was also removed with yields of around 40 %. The iron precipitated in good yields reaching over 90 %. On the other hand, Mn showed too low precipitation yields of less than 40 % by the fact that it required real oxidizing conditions which could bring it back to its insoluble form of MnO2. Finally, with the considerations on the cost of acquisition on the Ruashi Mining site of 160 and 50 USD respectively for the ton of lime and limestone, without integrating the cost linked to the fragmentation of the limestone to have the correct grain size, it is technically possible to substitute lime by limestone.
Author Keywords: Purification by selective precipitation, Cobalt, Iron, Manganese, Lime and Limestone.
Volume 32, Issue 2, March 2021, Pages 220–229
L. Zeka1, A. Kafat2, F. Manene3, and A. Ilunga4
1 Département de Chimie Industrielle, Faculté Polytechnique, Université de Lubumbashi, B.P. 1825, Lubumbashi, RD Congo
2 Département de Métallurgie, Faculté Polytechnique, Université de Likasi, B.P. 1946, Likasi, RD Congo
3 Département de Chimie Industrielle, Faculté Polytechnique, Université de Lubumbashi, B.P. 1825, Lubumbashi, RD Congo
4 Département de Chimie Industrielle, Faculté Polytechnique, Université de Lubumbashi, B.P. 1825, Lubumbashi, RD Congo
Original language: French
Copyright © 2021 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The possibility of using limestone instead of lime as an agent precipitating impurities from cobalt-rich solutions from the hydrometallurgical plants of Ruashi Mining in R.D. Congo was studied. These solutions come from the copper solvent extraction circuit and are intended for the production of cobalt hydrates. Precipitation tests performed in the laboratory have shown that limestone competes with lime in terms of precipitation of Fe, Mn and Cu impurities and co-precipitation of Co. The parameters which were exploited are: Eh, pH, time, % Solid and the particle size. Reduced to the equivalent quantities which enter into a precipitation reaction with 1.5 as the evaluated value of the limestone/lime ratio, the consumption of these two precipitating agents is almost the same. Co-precipitation of cobalt was acceptable and was limited to a yield of 3.0 % Co. Under these same conditions, copper was also removed with yields of around 40 %. The iron precipitated in good yields reaching over 90 %. On the other hand, Mn showed too low precipitation yields of less than 40 % by the fact that it required real oxidizing conditions which could bring it back to its insoluble form of MnO2. Finally, with the considerations on the cost of acquisition on the Ruashi Mining site of 160 and 50 USD respectively for the ton of lime and limestone, without integrating the cost linked to the fragmentation of the limestone to have the correct grain size, it is technically possible to substitute lime by limestone.
Author Keywords: Purification by selective precipitation, Cobalt, Iron, Manganese, Lime and Limestone.
Abstract: (french)
La possibilité d’utiliser le calcaire en lieu et place de la chaux comme agent précipitant des impuretés des solutions cobaltifères des usines hydrométallurgiques de Ruashi Mining en R.D. Congo a été étudiée. Ces solutions proviennent du circuit de l’extraction par solvant du cuivre et sont destinées à la production des hydrates de cobalt vendables. Les tests de précipitation réalisés en laboratoire ont montré que le calcaire permet d’obtenir des résultats concurrentiels d’avec la chaux en termes de la précipitation des impuretés Fe, Mn et Cu et de la coprécipitation du Co. Les paramètres qui ont été exploités sont: Eh, pH, temps, % Solide et la granulométrie. Ramenée aux quantités équivalentes qui entrent en réaction de précipitation avec la valeur évaluée de 1,5 comme le ratio calcaire/chaux, la consommation de ces deux agents précipitants est quasiment la même. La coprécipitation du cobalt a été acceptable et s’est limitée à un rendement de 3,0 % Co. Dans ces mêmes conditions, le cuivre a été également été éliminé avec des rendements envoisinant 40 %. Le fer s’est précipité avec de bons rendements atteignant plus de 90 %. Par contre, le Mn a accusé des rendements de précipitation trop faibles de moins de 40 %. Enfin, avec les considérations sur le coût d’acquisition de 160 et 50 USD respectivement pour la tonne de chaux et de calcaire, sans intégrer le coût lié à la fragmentation du calcaire pour avoir la bonne granulométrie, il est possible techniquement de substituer la chaux par le calcaire.
Author Keywords: Purification par précipitation sélective, Cobalt, Fer, Manganèse, Chaux et Calcaire.
How to Cite this Article
L. Zeka, A. Kafat, F. Manene, and A. Ilunga, “Use of limestone as an agent precipitating impurities from cobalt-rich solutions at Ruashi Mining plants, D.R.C.,” International Journal of Innovation and Applied Studies, vol. 32, no. 2, pp. 220–229, March 2021.
