Doctoral thesis (Dissertations and theses)
Biolixiviation de la carrolite-Application aux minerais polymétalliques de l'Arc Cuprifère du Katanga (cas de minerais de la mine de Kamoya, Kambove) en RDC
Nkulu Wa Ngoie, Guy
2012
 

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Keywords :
Bioleaching; Carrolite; Arc Cuprifère du Katanga
Abstract :
[en] The present work focuses on the bioleaching of carrolite as pure mineral and application of bioleaching as an alternative technique for processing the polymetallic sulphide ores in Katanga copperbelt (case of Kamoya deposit ores) in Democratic Republic of Congo (DRC). A preliminary study on the bioleaching of carrolite in the presence of mesophilic bacteria has highlighted the effect of the initial pH (pH = 1.5, 2.0 and 2.5), particle size (-53μm, -75+53 µm, -106+75µm), the pulp density (dp= 2.5 and 10) on the pH, the solution redox and on the dissolution performance of copper, nickel and cobalt. The results obtained at this stage showed that the initial pH, particle size and pulp density greatly influences the process of bioleaching of carrolite. The evolution of pH, solution redox and the efficiency of metals dissolution with time considering these factors indicate the importance of bacterial growth. Good bacterial activity thereby yields high metal dissolution which is being obtained at initial pH 2.0, particle size of -53μm and 2% pulp density. A second study upon the bioleaching of carrolite has allowed highlighting the metal dissolution mechanism during the bioleaching process. The evolution of the bacterial population, observations of Optical Microscope (MO), Scanning Electron Microscope (SEM), Confocal Laser Scanning Microscope (CLSM) of carrolite grains during bioleaching and spectroscopical analysis in X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) of bioleaching residues allowed us to demonstrate the role and importance of bacteria attached on the surface of carrolite grains from one hand, and ferric ions on the other hand, during the carrolite bioleaching. Strong adhesion of bacteria to the surface of the carrolite grains was observed during early bioleach stages and playing an important role in the process. This phenomenon would cause the release of ferrous ions in solution by a direct contact mechanism on the one hand and causing oxidation of ferrous ions, elemental sulfur or sulfur compounds on the other hand, compounds which would accumulate at the surface of carrolite grains. The number of free bacteria in solution increases thus promoting the oxidation of ferrous to ferric ions, which oxidize the mineral through indirect mechanism. The number of free bacteria in solution and that of attached bacteria became constant over time, suggesting a cooperative mechanism of carrolite bioleaching. Finally, a statistical study of bioleaching of polymetallic concentrate from Kamoya deposit by Taguchi methodology and analysis of variance (ANOVA) was used to investigate the effect of different physicochemical parameters (initial pH, temperature, agitation, pulp density and duration of bioleaching) on the process efficiency. The results obtained from this statistical approach showed the possibility of bioleaching application as an alternative technique for treatment of the polymetallic sulphide ores of the Katanga copperbelt in Democratic Republic of Congo (DRC) but further investigation using thermophilic bacteria should be considered to improve metal dissolution.
Research center :
Service de Génie minéral et récyclage de l'Université de Liège
Disciplines :
Geological, petroleum & mining engineering
Author, co-author :
Nkulu Wa Ngoie, Guy ;  Université de Liège - ULiège > Doct. sc. ingé. (architecture, génie civ. & géol.)
Language :
French
Title :
Biolixiviation de la carrolite-Application aux minerais polymétalliques de l'Arc Cuprifère du Katanga (cas de minerais de la mine de Kamoya, Kambove) en RDC
Alternative titles :
[en] Bioleaching of carrolite-Application of Katanga sulphides ores (case study: Kamoya deposit ores, Kalbove) in DRC
Defense date :
05 December 2012
Number of pages :
222
Institution :
ULiège - Université de Liège
Degree :
Docteur en Sciences de l'Ingénieur
Promotor :
Gaydardzhiev, Stoyan  ;  Université de Liège - ULiège > Urban and Environmental Engineering
Name of the research project :
Biolixiviation de la carrolite
Funders :
BTC/CTB
Available on ORBi :
since 05 December 2012

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