Bio-Modification of Carbonaceous Matters in Gold Ore: Model Experiments Using Powdered Activated Charcoal and Cell-Free Extracts of Phanerochaete chrysosporium

The detailed mechanism behind the bio-decomposition of carbonaceous matter in refractroy goold ore byPhanerocheate chrysosporiumto facilitate improved cyanidation of gold is as yet undersdtood. To gain a better understanding of this mechanism, the present work model experiments using powdery activated carbon (PAC) and cell-free extracts ofP.chrysosporiumto simulate and focus on the biotransformation of carbonaceous matters in refractory gold ores. The results of solid characterization using SEM and XRD indicated a more non-uniform surface and smaller crystal sizes for PAC treaded with cell-free extracts for 72 hours. The significant decomposition of aromatic compounds into aliphatic compounds were observed in13C-NMR and FTIR results for the high ratio of cell-free extract volume to mass of PAC. This results support the theory that one of the fundamental mechanisms behind the bio-decomposition process is aromatic bond cleavage by biomolecules produced byP.chrysosporium.

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Biological pretreatment of carbonaceous matter in double refractory gold ores: A review and some future considerations

Hydrometallurgy ◽

10.1016/j.hydromet.2020.105434 ◽

2020 ◽

Vol 196 ◽

pp. 105434 ◽

Cited By ~ 1

Author(s):

Kojo T. Konadu ◽

Diego M. Mendoza ◽

Robert J. Huddy ◽

Susan T.L. Harrison ◽

Takashi Kaneta ◽

...

Keyword(s):

Carbonaceous Matter ◽

Biological Pretreatment ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold

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Fungal-Transformation of Surrogate Sulphides and Carbonaceous Matter in Refractory Gold Ores: Revisited

Ghana Mining Journal ◽

10.4314/gm.v17i2.8 ◽

2017 ◽

Vol 17 (2) ◽

pp. 56-65

Author(s):

G. Ofori-Sarpong ◽

D. K. Adjei ◽

R. K. Amankwah

Keyword(s):

Phanerochaete Chrysosporium ◽

Alternative Methods ◽

Fungal Transformation ◽

Carbonaceous Matter ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold ◽

Amorphous Nature ◽

Microbial Pretreatment ◽

Oxygen Groups

In the recovery of gold from refractory gold ores, pretreatment is required to decompose sulphides and liberate occluded gold before cyanidation, and to deactivate carbonaceous matter and prevent it from adsorbing dissolved gold. Until the past three decades, most commercial pretreatment processes had been by abiotic means. Biological pretreatment methods on commercial basis is therefore a recent phenomenon, and several researches are underway to assess the ability of different biological agents in the breakdown of sulphur and carbonaceous matter (CM) in gold ores. This paper, which is a revisit of an earlier one, presents an overview of on-going research aimed at assessing the capability of the fungus, Phanerochaete chrysosporium, to degrade sulphides and CM. Surrogate carbonaceous materials (lignite, bituminous and anthracite coals) and pure sulphides (pyrite and arsenopyrite) were used to model the behavior of CM and sulphides in refractory gold ores. To monitor the extent of biotransformation, preg-robbing test was conducted on the as-received and treated CM, and sulphide sulphur in the residual sulphidic materials was also determined. From an initial preg-robbing effect of 125 µg of gold per gram of CM, the ability of CM to preg-rob gold reduced by 70-95% in the order of lignite<bituminous <anthracite within 21 days of treatment, whereas there were 18% and 39% oxidation of sulphide sulphur in pyrite and arsenopyrite respectively. XRD examination of the treated anthracite confirmed reduction in the graphitic structure of carbon following fungal transformation. Similarly, there was a decline in the major sulphide peak after microbial pretreatment. The results indicate that the fungus biotransforms through destruction of the ordered structure, followed by introduction of oxygen groups. The amorphous nature, thus generated, inhibits the uptake of aurocyanide ions by CM, while enhancing the affinity of cyanide for the oxidised sulphide material in subsequent cyanidation treatment. The findings contribute to knowledge on novel and technically viable alternative methods for oxidative pretreatment of refractory gold ores. Keywords: Phanerochaete Chrysosporium, Carbonaceous Matter, Metal Sulphides, Biotransformation

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Enzymatic Pre-Treatment of Carbonaceous Matter in Preg-Robbing Gold Ores: Effect of Ferrous Ion Additives

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.262.43 ◽

2017 ◽

Vol 262 ◽

pp. 43-47

Author(s):

Kojo T. Konadu ◽

Keiko Sasaki ◽

Kwadwo Osseo-Asare ◽

Takashi Kaneta

Keyword(s):

Hydrogen Peroxide ◽

Activated Carbon ◽

Aromatic Compounds ◽

Ferrous Ion ◽

Alkaline Solutions ◽

Carbonaceous Matter ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold ◽

Pre Treatment

The bio-treatment of double refractory gold ores (DRGO) to reduce preg-robbing needs to account for the heterogeneity of the ore so as to acquire a much more complete picture of the system. To this end, the effects of ferrous ion additives on the degradation of powdered activated carbon (PAC) by cell-free spent medium (CFSM) was studied. Au(CN)2- adsorption and Raman spectrometric results suggest that the ferrous salt could have possibly reacted with some biogenic hydrogen peroxide to aid in the degradation of PAC. The bio-treatment produced mixed solid residues containing some partially degraded aromatic compounds which were soluble in alkaline solutions. Ultimately, biodegradation of PAC using CFSM in the presence of 50 µM FeSO4.7H2O for 7 days followed by washing with 3 mM NaOH reduced Au(CN)2- uptake by 80%.

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