Biooxidation of Refractory Gold Ores by Mixed Moderate Thermophiles in Airlift Bioreactor

2009 ◽  
Vol 71-73 ◽  
pp. 469-472 ◽  
Author(s):  
Xue Hui Xie ◽  
Sheng Mu Xiao ◽  
Hua Tai Wang ◽  
Jian She Liu
Keyword(s):  
Particle Size ◽  
Aeration Rate ◽  
Pulp Density ◽  
Airlift Bioreactor ◽  
Leaching Rate ◽  
Gold Ore ◽  
Refractory Gold ◽  
Initial Ph ◽  
Moderate Thermophiles ◽  
Arsenic Leaching

Bacterial preoxidation of refractory gold ore has showed many advantages, such as lower operation cost and environmental friendly. In this paper, biooxidation of refractory gold ore by mixed moderate thermophiles culture in airlift bioreactor has been well studied. Firstly, a laboratory scale airlift bioreactor unit has been designed for bacterial preoxidation of refractory gold ore, a mixed moderate thermophilic culture was incubated. The orthogonal experiment was performed to investigate the effects of particle size, pulp density, aeration rate and initial pH. The results showed that when particle size 37micrometer，pulp density 5%，aeration rate 4 dm3•s-1 and initial pH 1.2, the arsenic leaching rate achieved to 93.5%. On the base of the airlift bioreactor unit, a continuous airlift bioreactor was designed. The preoxidation of refractory gold ore by a mixed culture of moderately thermophilic bacteria also was investigated in this equipment. The results showed that, under the conditions of pulp density 8% and stay time 60h, it can deal with 0.256 kg refractory gold ore per day, and the arsenic leaching rate can reach to 95.25%. During the experiment, some leaching liquor has been sampled from the second sect the fourth column of the continuous airlift bioreactor. The composition of microbial communities in this sample has been investigated using culture-independent 16S rDNA based cloning approach- restriction fragment length polymorphism. The phylogenetic analysis revealed that Leptospirillum ferriphilum and Acidithiobacillus caldus are the main organisms in this system. Both of them are moderate thermphilic bacteria and can resist relatively high concentration of arsenic ion.

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

2017 ◽  
Vol 262 ◽  
pp. 65-69 ◽  
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.

Experimental Study on the Cyanidation of a Low-Grade Gold with High Content of Arsenic in Myanmar

2013 ◽  
Vol 734-737 ◽  
pp. 1041-1044
Author(s):  
Peng Yang ◽  
Gui Fang Zhang ◽  
Qing Rong Yang
Keyword(s):  
Experimental Study ◽  
Pulp Density ◽  
Low Grade ◽  
Leaching Rate ◽  
Mixing Effect ◽  
Gold Ore ◽  
Lime Water ◽  
Content Of Gold

The content of gold ore in Wa region of Myanmar is 3.52 g/t ~5.87g/t, and it contains 9.32% arsenic, it belongs to awkward gold ore with gold embeds in pyrite as fine granular. so the drawbacks of low leaching rate and wasting of resources existed in the early cyanide production. A technology of adjusting pH in lime water and further leaching after regrinding was confirmed by contrasting the mixing effect in different reagent. The experiment results showed that a leaching rate of 81.63% has been obtained by adopting the conditions which pulp density is 40%, the pH of pulp adjusted in lime water is 10, the total NaCN dosage of three additions is 3 and the material is reground before third addition.

Evaluation of Parameters in the Bio-Oxidation Process of Refractory Gold Minerals

2013 ◽  
Vol 825 ◽  
pp. 364-367
Author(s):  
Paulina Aguirre ◽  
Esvar Diaz ◽  
Juan C. Gentina
Keyword(s):  
Particle Size ◽  
Gold Recovery ◽  
Pulp Density ◽  
Mining District ◽  
Mountain Range ◽  
Low Grade ◽  
Recovery Processes ◽  
Oxidation Step ◽  
Refractory Gold ◽  
Evaluation Of Parameters

The mining districts located in the western mountain range in the south of Ecuador have gold minerals with refractory characteristics, which do not allow gold recovery by traditional methods used in Ecuador. Therefore, it is necessary to apply some technology that permits to obtain greater metal recovery. Bio-oxidation, as treatment of refractory ores that contain low grade of gold, offers an economic and sustainable alternative for this purpose. The objective of this research was to evaluate the effect of particle size, pulp density and concentration of inoculum and inducer (Fe+2) on the bio-oxidation of refractory gold minerals in order to maximize gold recovery of the bioleached minerals by means of a cyanidation process. The microbial consortium used in this work was collected and isolated from the Portovelo mining district corresponding mostly toAcidithiobacillus ferrooxidansandLeptospirillum ferrooxidansspecies. The Eh, final concentration of ferric ion, total iron and sulfates were measured. Finally, the bio-oxidized material was tested using cyanidation to determine the gold recovery. The results after the cyanidation tests showed that the highest gold recovery was obtained when the bio-oxidation step was conducted with 68-91 µm particle size, 15% pulp density, 20% v/v inoculum and 2 g/L of Fe2+as inducer. At those conditions, gold recovery was 68% compared to 26% obtained when no bio-oxidation step was performed, demonstrating that this process was favorable compared with traditional gold recovery processes

scholarly journals Bioleaching of Cu and Zn from Complex Sulfide using an Isolated Iron Oxidizing Bacteria

2020 ◽  
Vol 10 (1) ◽  
pp. 1825-1832
Keyword(s):  
Metal Sulfide ◽  
Pulp Density ◽  
Leaching Rate ◽  
Metal Dissolution ◽  
Iron Oxidizing Bacteria ◽  
Complex Sulfide ◽  
Initial Ph ◽  
Leaching Parameters ◽  
Kinetics Of ◽  
Sulfide Concentrate

Bioleaching kinetics of copper and zinc from a complex sulfide concentrate sample was evaluated in this manuscript. An acidophilic microorganism was used for the metal dissolution. The metal dissolution was evaluated based on the variation of leaching parameters like initial pH, pulp density, and initial ferrous concentration. The leaching rate of metals increased with the increase of initial ferrous concentration up to 20g/L, and it decreased on a further increase of the initial ferrous concentration. It decreased at the initial ferrous concentration above 20g/L due to the formation of an iron precipitate, which did not allow the contact of lixiviant with the metal sulfide matrix. The leaching rate increased with the increase of initial pH up to 2.0, and thereafter it decreased. Similarly, the leaching rate remained unchanged up to pulp density of 15%(w/v), and it decreased upon further increase of the pulp density due to the mutual completion of the complex sulfide particles towards the lixiviants.

The Oxidation Pretreatment of a Sulfidic Refractory Gold Ore with Pyrolusite

2012 ◽  
Vol 550-553 ◽  
pp. 2891-2894 ◽  
Author(s):  
Su Rong Hu ◽  
Chao Wang ◽  
Qi Feng Wei
Keyword(s):  
Particle Size ◽  
Precious Metal ◽  
Mass Ratio ◽  
Gold Ore ◽  
Refractory Gold

An attempt has been made to study the pretreatment of sulfidic refractory gold ore with pyrolusite. The influences of various parameters were studied to optimize the conditions. The optimum leaching conditions were pyrolusite/gold ore mass ratio of 3.0, H2SO4concentration of 3.0 M, temperature of 100°C, particle size of 45μm, stirring speed of 200 rpm. After the pretreatment, gold and silver were exposed, these made the extraction of the precious metal in the gold ore much easier.

Bioleaching Experiments on a Low-Grade Complex Zinc Ore from Inner Mongolia

2017 ◽  
Vol 262 ◽  
pp. 155-158
Author(s):  
Jia Feng Li ◽  
Lin Lin Tong ◽  
Qiao Chen ◽  
Zhe Nan Jin ◽  
Hong Ying Yang
Keyword(s):  
Inner Mongolia ◽  
High Energy ◽  
Economic Benefits ◽  
Aeration Rate ◽  
Low Grade ◽  
Leaching Rate ◽  
Initial Stage ◽  
Initial Ph ◽  
Efficient Processing ◽  
High Energy Consumption

When dealing with a low-grade complex Zinc ore from Inner Mongolia, problems of low leaching rate, high energy consumption, low economic benefits and pollution were encountered. To treat this low-grade zinc ore economically and effectively, bioleaching was used. This approach produces reliable data for an environmentally friendly and efficient processing of the zinc ore. The results indicate that Zinc occurs in the ore mainly as sphalerite, the latter also containing Indium. The experimental results demonstrated an excellent leaching performance: A leaching rate of nearly 100% is achieved at a temperature of 45°C, a pulp concentration of 10%, an initial pH of 1.8, and an aeration rate of 0.8m3/h. In the initial stage the leaching rate is higher than at the end. It starts with 85% of zinc leaching rate in three days. The Indium in the sphalerite is leached almost completely. This makes a further comprehensive use of such resources possible.

Experimental Research on Cyanidation Leaching of a Gold Ore

2012 ◽  
Vol 550-553 ◽  
pp. 2835-2839
Author(s):  
Wei Zhi Wang ◽  
Miao Miao Han ◽  
Chun Guang Yang
Keyword(s):  
Experimental Research ◽  
Experimental Studies ◽  
Copper Ion ◽  
Sodium Cyanide ◽  
Extraction Time ◽  
Pulp Density ◽  
Leaching Rate ◽  
Cyanide Leaching ◽  
Gold Ore ◽  
Good Index

The gold ore is oxidized ores, and it is not suitable for flotation separation. The cyanide leaching is used for the recovery of gold. Experimental studies of cyanidation leaching for a oxidized gold ore were carried out. The factors that influence leaching such as grinding size, sodium cyanide quantity, pulp density, extraction time and segmentation leaching were conducted. And experiment pretreatment test with the copper ion which influences leaching. The results demonstrated that the good index of leaching rate 90.11% could be reach.

Biooxidation of High-Sulfur Refractory Gold Concentrate by Ferroplasma acidiphilum

2014 ◽  
Vol 997 ◽  
pp. 642-645 ◽  
Author(s):  
He Shang ◽  
Jian Kang Wen ◽  
Biao Wu
Keyword(s):  
Pulp Density ◽  
Cyanide Leaching ◽  
Gold Extraction ◽  
Pressure Oxidation ◽  
Gold Ores ◽  
Refractory Gold Ores ◽  
Refractory Gold ◽  
Initial Ph ◽  
Pre Treatment ◽  
Number Of Bacteria

Gold ores can be categorized into two types-free milling and refractory. Free milling ores are easy to treat. Gold in such ores is recovered by gravity separating techniques or direct cyanidation. Refractory gold ores, on the contrary, are difficult to treat and require pre-treatment prior to cyanidation, such as roasting, pressure oxidation, fine grinding and biooxidation. A number of bacteria are used in biomining but the prominent ones that are known to be involved in the oxidation of sulfide ores include Thiobacillusferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. In this study, the gold concentrate was biooxidized in a reactor at 45°C over a period of 10 days at a pulp density of 15% solids using a culture of already grown Ferroplasma acidiphilum. The initial pH was adjusted to 1.5 with sulfuric acid, resulted in 85.39 % oxidation of sulfur from initial grade of 33.83 %, and the slag rate was 68.52 %. The products of sulfide biooxidation were leached at a pulp density of 20 %(v/w) for 24 h at pH 11. The pH was adjusted using CaO and cyanide strength was 10 kg/t, we got a gold extraction of 90.71 %, which ncreaseed 80.09 % compared with the direct cyanide leaching.

Arsenic release through refractory gold ore processing. Immobilization and decontamination approaches

2021 ◽  
Vol 20 ◽  
pp. 100236
Author(s):  
Michail Samouhos ◽  
Antoniοs Peppas ◽  
Georgios Bartzas ◽  
Maria Taxiarchou ◽  
Petros E. Tsakiridis
Keyword(s):  
Gold Ore ◽  
Ore Processing ◽  
Refractory Gold
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