Optimisation of efficient auxiliary agents of gold leaching in an alkaline thiourea solution for a finely disseminated gold ore

Carbonaceous sulfidic gold ores are commonly double refractory and thus require pretreatment before gold extraction. In this paper, the capacity of pre-bio-oxidation can simultaneously decompose sulfides or deactivate carbonaceous matters (CM) from a double refractory gold ore (DRGO) using pure cultures of A. ferrooxidans or L. ferrooxidans, and a mixed culture containing A. ferrooxidans and L. ferrooxidans was investigated. The results showed that direct thiourea leaching of the as-received DRGO yielded only 28.7% gold extraction, which was due to the encapsulation of sulfides on gold and the gold adsorption of CM. After bio-oxidation, thiourea leaching of the DRGO resulted in gold extraction of over 75–80%. Moreover, bio-oxidation can effectively reduce the adsorption of carbon to gold. XRD, SEM-EDS and FTIR analysis showed that many oxygen-containing groups were introduced on the surface of DRGO during bio-oxidation, while the C=C bond was cleaved and the O–C–O and C–N bonds were degraded, causing a decrease in active sites for gold adsorption. Moreover, passivation materials such as jarosite were formed on the surface of DRGO, which might reduce the affinity of CM for gold in solutions. In addition, the cleavage of the S–S band indicated that sulfides were oxidized by bacteria. This work allows us to explain the applicability of pre-bio-oxidation for degrading both sulfides and CM and increasing gold recovery from DRGO in the thiourea system.

Download Full-text

Fast and Effective Gold Leaching from a Desulfurized Gold Ore Using Acidic Sodium Chlorate Solution at Low Temperature

Industrial & Engineering Chemistry Research ◽

10.1021/ie4026852 ◽

2013 ◽

Vol 52 (47) ◽

pp. 16622-16629 ◽

Cited By ~ 11

Author(s):

Yao Cheng ◽

Shaobo Shen ◽

Jiantao Zhang ◽

Shuai Chen ◽

Lei Xiong ◽

...

Keyword(s):

Low Temperature ◽

Sodium Chlorate ◽

Gold Leaching ◽

Gold Ore

Download Full-text

Biooxidation of a Refractory Gold Ore: Implications of Whole-Ore Heap Biooxidation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.262.65 ◽

2017 ◽

Vol 262 ◽

pp. 65-69 ◽

Cited By ~ 1

Author(s):

Bo Wei Chen ◽

Jian Zhi Sun ◽

He Shang ◽

Biao Wu ◽

Jian Kang Wen

Keyword(s):

Pulp Density ◽

Tianshan Mountain ◽

Gold Mine ◽

Gold Extraction ◽

Gold Leaching ◽

Gold Ore ◽

Refractory Gold ◽

Gold Reserve ◽

Initial Ph ◽

South Tianshan

The Sawayardun Gold Mine, the first Muruntau type gold mine in China, was located in the south Tianshan Mountain, Xinjiang Province. The gold reserve was 127 t with an average gold grade of 2.36 g/t. Due to the high content of arsenic and antimony, the traditional flotation-roasting-cyanidation process was not suitable. The direct cyanidation gold extraction for the raw ore was 44.70 %. Thus, biooxidation experiments in shaker flasks were conducted for this ore. The optimum conditions were obtained as inoculation volume 10 %, initial pH 1.7, pulp density 15 %, temperature 33 °C, leaching time 10 days, with the arsenic oxidation rate of 75.12 %. Then the biooxidation residues were test for gold leaching using NaCN, green gold leaching agent and thiourea. After 24 h leaching rate at pulp density of 33%, gold leaching agent dosage of 2 kg/t ore, the gold extraction for NaCN, green gold leaching agent and thiourea were 91.50 %, 86.23 % and 91.09 %, respectively. The high gold extraction showed a bright future for the whole-ore heap biooxidation of this refractory gold ore.

Download Full-text

Effect of Na2SO3 on electrochemical aspects of gold dissolution in alkaline thiourea solution

Hydrometallurgy ◽

10.1016/s0304-386x(99)00051-1 ◽

1999 ◽

Vol 53 (3) ◽

pp. 255-266 ◽

Cited By ~ 27

Author(s):

Liyuan Chai ◽

Masazumi Okido ◽

Wanzhi Wei

Keyword(s):

Gold Dissolution ◽

Alkaline Thiourea ◽

Thiourea Solution

Download Full-text

Mechanism of gold dissolving in alkaline thiourea solution

Journal of Central South University of Technology ◽

10.1007/s11771-007-0094-0 ◽

2007 ◽

Vol 14 (4) ◽

pp. 485-489 ◽

Cited By ~ 4

Author(s):

Li-yuang Chai ◽

Yun-yan Wang

Keyword(s):

Alkaline Thiourea ◽

Thiourea Solution

Download Full-text

Effect of Initial Cell Concentration on Bio-Oxidation of Pyrite before Gold Cyanidation

Minerals ◽

10.3390/min11080834 ◽

2021 ◽

Vol 11 (8) ◽

pp. 834

Author(s):

Ka Yu Cheng ◽

Caroline C. Rubina Rubina Acuña ◽

Naomi J. Boxall ◽

Jian Li ◽

David Collinson ◽

...

Keyword(s):

Performance Enhancement ◽

Cell Concentration ◽

Pyrite Oxidation ◽

Pulp Density ◽

Initial Cell Concentration ◽

Gold Leaching ◽

Initial Cell ◽

Gold Ore ◽

Commercial Scale ◽

Pre Treatment

Bio-oxidation of refractory sulfidic gold minerals has been applied at the commercial scale as a pre-treatment to improve gold yields and reduce chemical consumption during gold cyanidation. In this study, the effect of initial cell concentration on the oxidation of pyritic gold ore was evaluated with four aerated bioreactors at 30 °C with 10% pulp density and pH maintained at 1.4 with NaOH. Results of NaOH consumption and changes in soluble Fe and S concentrations indicated that increasing the initial cell concentration from 2.3 × 107 to 2.3 × 1010 cells mL−1 enhanced pyrite oxidation during the first week. However, by day 18 the reactor with the lowest initial cell concentration showed profound performance enhancement based on soluble Fe and S concentrations, sulfide-S and pyrite contents in the residues, and subsequent gold leaching of the bio-oxidation residues by cyanidation. Overall, the results showed that the cell concentration was clearly beneficial during the initial stages of oxidation (first 7–8 days).

Download Full-text