Bioleaching of a Rich-In-Carbonates Copper Ore at Alkaline pH

Abstract

A rich-in- carbonates copper ore was subjected to bioleaching under alkaline pH conditions by means of different microorganisms or their metabolites. The ore contained 1.40% copper, 1.94% sulphur, 3.25% iron and 20.3% carbonates, and had a pH of 8.6 and a highly positive net neutralization potential (325 kg CaCO3/t). Copper was present mainly as different sulphide minerals (bornite, covellite, chalcopyrite). The leaching was carried out by means of the shake-flask technique at 32 oC using finely ground (minus 100 μm) ore. The following microorganisms were used to leach the sample: ammonifying bacteria (related to the genera Bacillus, Acinetocater and Vibrio); heterotrophic bacteria (Acetobacter and Pseudomonas) and fungi (Asperillus niger and Penicillium chrysogenum) producing citric acid; heterotrophic bacteria (Micrococcus, Alcaligenes and Bacillus) producing amino acids (mainly alanine); basophilic chemolithotrophic bacteria (Thiobacillus thioparus, Hallothiobacillus neapolitanus, Starkeya novella; ”silicate bacteria” (Bacillus circulans) producing organic acids and exopolysaccharides; bacteria possessing urease enzymatic activity (Corynebacterium). The best results were achieved by means of a mixed culture of urease-possessing bacteria, which under certain conditions was able to solubilize 64.4% of the copper within 30 days of leaching.

Effects of bioleaching on the chemical, mineralogical and morphological properties of natural and waste-derived alkaline materials

“…The alkaline bioleaching potential of the following microorganisms has been reported in literature: A. niger (Wu and Ting, 2006;De Windt and Devillers, 2010;Ball and Banik, 2011), Humicola grisea (Kulkarni et al, 2008), Penicillium chrysogenum (Groudeva et al, 2007), Bacillus circulans (Vrvić et al, 1990;Ball et al, 2010), Bacillus licheniformis (Mohanty et al, 1990), B. mucilaginosus (Liu et al, 2006;Yang et al, 2010), and Sporosarcina ureae (Chandraprabha and Natarajan, 2010). These studies concerned the bioleaching of the following alkaline materials: oil shale (Vrvić et al, 1990), chromite ore (Ball et al, 2010;Ball and Banik, 2011), magnesite ore (Mohanty et al, 1990), municipal solid waste incineration fly ash (Wu and Ting, 2006;Yang et al, 2010), Portland cement (De Windt and Devillers, 2010), borosilicate glass (Kulkarni et al, 2008), richin-carbonates copper ore (Groudeva et al, 2007), mica and feldspar (Liu et al, 2006).…”

“…Application of bioleaching in industrial processes is analogous to the acceleration of naturally occurring biodegradation and biodeterioration, which are attributable to mechanical and aesthetic wearing of stony and cementitious construction materials (Warscheid and Braams, 2000;De Belie, 2010;Wiktor et al, 2011). Bioleaching can lead to the extraction of valuable components from raw materials (Groudeva et al, 2007), and the extraction of hazardous components present in waste materials, which reduces the toxicity enabling reutilisation or valorisation (Wu and Ting, 2006;Yang et al, 2010). It can also change the mineralogy of the material, thus altering its reactivity and crystallinity/amorphicity (De Windt and Devillers, 2010).…”

Microbial cooperation improves bioleaching recovery rates

“…However, current bioleaching applications utilise the autotrophic oxidation of ferrous and reduced sulphur compounds for mineral release and subsequent recovery, which are found in low amounts in REE ore bodies. Nevertheless, studies of REE mineral extraction from phosphate ores by bioleaching are in their infancy [8][9][10] . These bioleaching activities utilise acidophilic and For example, the fungal species Penicillium tricolor was shown to leach 30-70% of available REEs from red mud 9 compared to Bacillus megaterium, which leached less than 1% from monazite 11 .…”