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

Minerals ◽  
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).

The comparison of trichloroethylene removal rates by methane- and aromatic-utilizing microorganisms

1998 ◽  
Vol 38 (7) ◽  
pp. 19-24 ◽  
Author(s):  
C.-J. Lu ◽  
C. M. Lee ◽  
M.-S. Chung
Keyword(s):  
Cell Concentration ◽  
Removal Rate ◽  
Carbon Sources ◽  
Batch Reactors ◽  
Initial Cell Concentration ◽  
Removal Rates ◽  
Initial Cell ◽  
Toluene Concentration ◽  
Cell Source ◽  
Removal Efficiencies

The comparison of TCE cometabolic removal by methane, toluene, and phenol utilizers was conducted with a series of batch reactors. Methane, toluene, or phenol enriched microorganisms were used as cell source. The initial cell concentration was about 107 cfu/mL. Methane, toluene, and phenol could be readily biodegraded resulting in the cometabolic removal of TCE. Among the three primary carbon sources studied, the presence of phenol provided the best cometabolic removal of TCE. When the concentration of carbon source was 3 mg-C/L, the initial TCE removal rates initiated by methane, toluene, and phenol utilizers were 1.5, 30, and 100 μg/L-hr, respectively. During the incubation period of 80 hours, TCE removal efficiencies were 26% and 96% with the presence of methane and toluene, respectively. However, it was 100% within 20 hours with the presence of phenol. For phenol utilizers, the initial TCE removal rates were about the same, when the phenol concentrations were 1.35, 2.7, and 4.5 mg/L. However, TCE removal was not proportional to the concentrations of phenol. TCE removal was hindered when the phenol concentration was higher than 4.5 mg/L because of the rapid depletion of dissolved oxygen. The presence of toluene also initiated cometabolic removal of TCE. The presence of toluene at 3 and 5 mg/L resulted in similar TCE removal. The initial TCE removal rate was about 95 μg/L-hr at toluene concentrations of 3 and 5 mg/L compared to 20 μg/L-hr at toluene concentration of 1 mg/L.

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.

scholarly journals THE EFFECT OF THE INITIAL CELL CONCENTRATION UPON SURVIVAL OF BACTERIA AT −22 C

1955 ◽  
Vol 69 (3) ◽  
pp. 244-249 ◽  
Author(s):  
Cecil P. Major ◽  
John D. McDougal ◽  
Arthur P. Harrison
Keyword(s):  
Cell Concentration ◽  
Initial Cell Concentration ◽  
Initial Cell

The Effect of Initial Cell Concentration on Xylose Fermentation by Pichia stipitis

2007 ◽  
pp. 653-662 ◽  
Author(s):  
Frank K. Agbogbo ◽  
Guillermo Coward-Kelly ◽  
Mads Torry-Smith ◽  
Kevin Wenger ◽  
Thomas W. Jeffries
Keyword(s):  
Xylose Fermentation ◽  
Cell Concentration ◽  
Pichia Stipitis ◽  
Initial Cell Concentration ◽  
Initial Cell

scholarly journals The Growth ofMonoraphidiumsp. andScenedesmussp. Cells in the Presence of Thorium

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Juliana Cristina de Queiroz ◽  
Ana Cristina de Melo Ferreira ◽  
Antonio Carlos Augusto da Costa
Keyword(s):  
Cell Concentration ◽  
Direct Count ◽  
Initial Cell Concentration ◽  
Initial Cell ◽  
Count Method ◽  
Low Concentrations ◽  
Direct Counting ◽  
Presence And Absence ◽  
Positive Effect

Toxicity of thorium byMonoraphidiumsp. andScenedesmussp. was studied. Microalgal cultures were inoculated in ASM-1 medium in presence and absence of thorium. Its effect was monitored by direct counting on Fuchs-Rosenthal chamber and with software. The toxicity of thorium over the species was observed for concentrations over 50.0 mg/L. After 30 days,Monoraphidiumcells decreased their concentration from4.23×106to4.27×105and8.57×105 cells/mL, in the presence of 50.0 and 100.0 mg/L of thorium, respectively.Scenedesmussp. cells were more resistant to thorium: for an initial cell concentration of7.65×104 cells/mL it was observed a change to5.25×105and5.12×105 cells/mL, in the presence of thorium at 50.0 and 100.0 mg/L, respectively. This is an indication that low concentrations of the radionuclide favored the growth, and thatScenedesmuscells are more resistant to thorium thanMonoraphidiumcells. The software used for comparison with direct count method proved to be useful for the improvement of accuracy of the results obtained, a decrease in the uncertainty and allowed recording of the data. The presence of thorium suggests that low concentrations have a positive effect on the growth, due to the presence of the nitrate, indicating its potential for ecotoxicological studies.

The effect of initial cell concentration on xylose fermentation by Pichia stipitis

2007 ◽  
Vol 137-140 (1-12) ◽  
pp. 653-662 ◽  
Author(s):  
Frank K. Agbogbo ◽  
Guillermo Coward-Kelly ◽  
Mads Torry-Smith ◽  
Kevin Wenger ◽  
Thomas W. Jeffries
Keyword(s):  
Xylose Fermentation ◽  
Cell Concentration ◽  
Pichia Stipitis ◽  
Initial Cell Concentration ◽  
Initial Cell

Modeling the effect of initial cell concentration and soluble solids on the plasma inactivation of yeast in apple juices

LWT ◽  
2021 ◽  
pp. 112227
Author(s):  
Xiaowei Bao ◽  
Zirong Wang ◽  
Wenle Zhang ◽  
Haiyan Yang ◽  
Xuan Zhu ◽  
...  
Keyword(s):  
Cell Concentration ◽  
Soluble Solids ◽  
Initial Cell Concentration ◽  
Initial Cell
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