Improving gold recovery from refractory gold ores through biooxidation using iron-sulfur-oxidizing/sulfur-oxidizing mixotrophic bacteria

Mubarok, Mohammad Zaki; Winarko, Ronny; Chaerun, Siti Khodijah; Rizki, Intan Nurul; Ichlas, Zela Tanlega

doi:10.1016/j.hydromet.2016.10.018

Cited by 69 publications

(34 citation statements)

References 11 publications

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“…A local mixotrophic bacterium used in this study was isolated from an Indonesian mine site (designated SKC2), which has the ability to oxidize iron and sulfur and produce extracellular polymeric substances (EPS) ( Mubarok et al, 2017 ). Based on the 16S rRNA sequencing analysis, this bacterium was identified as Citrobacter sp.…”

Section: Methodsmentioning

confidence: 99%

Bioleaching of Indonesian Galena Concentrate With an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium at Room Temperature

2020

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Biohydrometallurgy is believed to be a promising future study field for the recovery of lead (Pb) from ores/concentrates since the pyrometallurgical/hydrometallurgical processes have been largely applied to recover Pb to date, which operates at high temperature and generates volatile Pb matters that are hazardous and carcinogenic to human health. Hence, the main purpose of this study was to investigate the biohydrometallurgical extraction of Pb from the Indonesian galena concentrate through bioleaching using an iron- and sulfur-oxidizing mixotrophic bacterium (identified as Citrobacter sp.). The bioleaching experiments were conducted in shake flasks containing the modified LB broth medium supplemented with galena concentrate with a particle size of d 80 = 75 μm at room temperature. Both semi-direct and direct bioleaching methods were employed in this study. The bacterium was able to extract lead (Pb) from galena concentrate with high selectivity to Cu and Zn (0.99 and 0.86, respectively). The highest extraction level of 90 g lead dissolved/kg galena concentrate was achieved using direct bioleaching method at bioleaching conditions of 2% w/v pulp density, 5 g/L FeCl 3 , 50 g/L NaCl, 20 g/L molasses and a rotation speed of 180 rpm at room temperature (25°C). The addition of FeCl 3 , NaCl, and molasses increased the lead leaching efficiencies, which were also evidenced by the FTIR, XRD, and SEM-EDS analyses. From industrial and commercial standpoints, the selective bioleaching represented in this study may be beneficial to the development of lead leaching from sulfide minerals, since insoluble anglesite (PbSO 4 ) precipitates are formed during ferric sulfate oxidation, thus making the recovery of lead through bioleaching unpractical.

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Section: Methodsmentioning

confidence: 99%

Bioleaching of Indonesian Galena Concentrate With an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium at Room Temperature

2020

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“…Regardless, this biotechnology is still the theme of several studies 1,2,4,5,[8][9][10][11] and extractions above 85% are commonly reported. 2,4,5,8,10 For instance, 86% gold extraction was achieved through cyanidation from both a gold-bearing sulfide concentrate and a flotation tailing bio-oxidized by Acidithiobacillus ferrooxidans at 32°C, 10% (w/v) pulp density, pH 1.75, 5.0 g L −1 Fe 2+ with a residence time of 14 days. Besides that, the gold extraction was only 21% for the non-bio-oxidized material samples.…”

Section: Introductionmentioning

confidence: 99%

Recovering gold from mine tailings: a selection of reactors for bio‐oxidation at high pulp densities

Rodrigues

Giardini²,

Pereira³

et al. 2020

J of Chemical Tech & Biotech

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BACKGROUND: Biomining is one of the few cost-effective technologies that can be applied to low-grade ores and also mining tailings. In the current work, the bio-oxidation of a gold sulfide flotation tailing at high pulp densities was investigated and information concerning the high cyanide consumption commonly reported in bio-oxidative processes is discussed in order to promote less use of this chemical reagent during cyanidation. RESULTS: Various reactors were compared alongside the performance of strains of At. ferrooxidans and S. thermosulfidooxidans. Shaking flask tests performed using 5% (w/v) solids revealed that the mesophiles presented a faster adaptation to the solids and resulted in better tailings oxidation as compared to the moderate thermophile. Rolling bottle (pilot-scale rotating drum) experiments, carried out afterwards, enabled the adaptation of the At. ferrooxidans strain to 20% (w/v) solids. This adapted strain was thus utilized in a 10 L stirred tank reactor (pilot-scale stirred tank) experiment at the same pulp density. The concentration of the ferrous iron used in the bio-oxidation step had a detrimental effect on the cyanide consumption during cyanidation of the bio-oxidized material. The cyanide consumption varied from 6.9 to 13.7 kg t −1 as the initial Fe 2+ concentration increased from 0.0 to 10.0 g L −1 Fe 2+ , respectively, in the shaking flasks. CONCLUSIONS: Higher pulp densities (20% (w/v) solids) resulted in a lower cyanide consumption, which was around 7.0 kg t −1 in the experiments carried out in both rolling bottle and stirred tank reactors when 5.0 g L −1 Fe 2+ was used during bio-oxidation. This cyanide consumption was associated with a gold extraction of around 95%.

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“…Apart from that, there is poor understanding of the nature of the gold ores. Some ores are refractory and they need pre-treatment prior to leaching [6,7].…”

Section: Introductionmentioning

confidence: 99%

Optimisation of gold recovery from small scale custom mills

Nheta¹,

Nkwinika²,

Mailula³

2020

World Congress on Mechanical, Chemical, and Material Engineering

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Custom mill tailings generated during the treatment of gold ores in Custom milling plants contains a considerable significant amount of gold (Au) and Silver (Ag). The potential of recovering gold and silver from the tailings by cyanidation leaching process was investigated. The custom mill tailings were characterised using Malvern particle analyser, XRF, XRD and SEM-EDs. In this study, the MiniTab software experimental design method was used to determine the optimum leaching conditions. The PSD results revealed that the custom mill tailings are coarse with 80% passing 2000µm. The tailings are a quartzite material containing minor amount of sulphides such as pyrite, chalcopyrite and pentlandite. The amount of these sulphides is very low ruling the probability of the tailings being refractory. Recoveries of 88 and 95% for gold and silver respectively were achieved leaching at 800g/t NaCN 8hrs. However, gold recovery above 85% was achieved by leaching in 600g/t NaCN for 8 hrs. Custom mill tailings have proved to be a source of precious metals and Min Tab software is a useful tool in optimisation of the leaching conditions.

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Improving gold recovery from refractory gold ores through biooxidation using iron-sulfur-oxidizing/sulfur-oxidizing mixotrophic bacteria

Cited by 69 publications

References 11 publications

Bioleaching of Indonesian Galena Concentrate With an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium at Room Temperature

Bioleaching of Indonesian Galena Concentrate With an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium at Room Temperature

Recovering gold from mine tailings: a selection of reactors for bio‐oxidation at high pulp densities

Optimisation of gold recovery from small scale custom mills

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