scholarly journals Consideration of Influential Factors on Bioleaching of Gold Ore Using Iodide-Oxidizing Bacteria

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 274 ◽  
Author(s):  
San Yee Khaing ◽  
Yuichi Sugai ◽  
Kyuro Sasaki ◽  
Myo Min Tun
Keyword(s):  
Potassium Iodide ◽  
Bacterial Cell ◽  
Cell Number ◽  
Culture Solution ◽  
Gold Dissolution ◽  
Marine Broth ◽  
Gold Leaching ◽  
Temperature Range ◽  
Gold Ore ◽  
Bacterial Cell Number

Iodide-oxidizing bacteria (IOB) oxidize iodide into iodine and triiodide which can be utilized for gold dissolution. IOB can be therefore useful for gold leaching. This study examined the impact of incubation conditions such as concentration of the nutrient and iodide, initial bacterial cell number, incubation temperature, and shaking condition on the performance of the gold dissolution through the experiments incubating IOB in the culture medium containing the marine broth, potassium iodide and gold ore. The minimum necessary concentration of marine broth and potassium iodide for the complete gold dissolution were determined to be 18.7 g/L and 10.9 g/L respectively. The initial bacterial cell number had no effect on gold dissolution when it was 1 × 104 cells/mL or higher. Gold leaching with IOB should be operated under a temperature range of 30–35 °C, which was the optimal temperature range for IOB. The bacterial growth rate under shaking conditions was three times faster than that under static conditions. Shaking incubation effectively shortened the contact time compared to the static incubation. According to the pH and redox potential of the culture solution, the stable gold complex in the culture solution of this study could be designated as gold (I) diiodide.

Antibacterial activity of the seminal plasma of Paracentrotus lividus

1994 ◽  
Vol 72 (7) ◽  
pp. 1211-1216 ◽  
Author(s):  
Loredana Stabili ◽  
Calogero Canicattì
Keyword(s):  
Antibacterial Activity ◽  
Seminal Plasma ◽  
Bacterial Growth ◽  
Bacterial Cell ◽  
Inhibitory Action ◽  
Paracentrotus Lividus ◽  
Cell Number ◽  
Morphological Examination ◽  
Bacterial Cell Number ◽  
Antibacterial Factor

Seminal plasma from Paracentrotus lividus exerted an inhibitory action on the growth of bacterial colonies. The antibacterial reaction took 30 min to reach full expression and depended on both the dose of seminal plasma and the bacterial cell number. Heating at 56 °C for 60 min did not lower the antibacterial power of the seminal plasma. Morphological examination of bacteria treated with seminal plasma revealed a conspicuous alteration of their surface and suggested a lytic mode of action for the antibacterial factor(s). Lysozyme could be involved in this process. In fact, inhibition of bacterial growth strongly decreased when this hydrolase was inactivated by heating at a basic pH.

scholarly journals Efficacy Bacteriophage in Removal Pseudomonas aeruginosa from Infectious Surfaces

2021 ◽  
Author(s):  
Golnar Rahimzadeh ◽  
Mohammad Sadegh Rezai
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nosocomial Infection ◽  
Nosocomial Infections ◽  
Bacterial Cell ◽  
Cell Number ◽  
Biocontrol Agents ◽  
Hospital Environment ◽  
Bacterial Cells ◽  
Bacterial Cell Number

Nosocomial infections can be transmitted by contaminated hospital surfaces with resistant pathogens. conventional sanitations are not efficiently contributing to removing resistant pathogens. Bacteriophages suggest as decontaminating agents, safe, their selective ability to kill specific bacteria. This work aimed to assess the efficiency of a phage in removing Pseudomonas aeruginosa from different hard surfaces. The decontamination ability of phages w was tested in vitro against Pseudomonas aeruginosa strain. Cystoviridae Phages with titer (2 × 1012 PFU/mL) can efficiently reduce viable bacterial cells on contaminated surfaces. The treated surfaces with alcohol 70% and phage showed an evident drop of bacterial cell number from 1 h to 24 h. These results suggest that bacteriophages are biocontrol agents removing nosocomial infection pathogens transmitted by contaminated surfaces in the hospital environment.

scholarly journals Estimation of lactic acid bacterial cell number by DNA quantification

2018 ◽  
Vol 12 (2) ◽  
pp. 88-91 ◽  
Author(s):  
Masaki Ishii ◽  
Yasuhiko Matsumoto ◽  
Kazuhisa Sekimizu
Keyword(s):  
Lactic Acid ◽  
Bacterial Cell ◽  
Cell Number ◽  
Dna Quantification ◽  
Bacterial Cell Number

Development of a bioluminescent ATP assay to quantify mammalian and bacterial cell number from a mixed population

Biomaterials ◽  
2003 ◽  
Vol 24 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Sarah J. Dexter ◽  
Miguel Cámara ◽  
Martyn Davies ◽  
Kevin M. Shakesheff
Keyword(s):  
Bacterial Cell ◽  
Cell Number ◽  
Mixed Population ◽  
Atp Assay ◽  
Bacterial Cell Number

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

2013 ◽  
Vol 52 (47) ◽  
pp. 16622-16629 ◽  
Author(s):  
Yao Cheng ◽  
Shaobo Shen ◽  
Jiantao Zhang ◽  
Shuai Chen ◽  
Lei Xiong ◽  
...  
Keyword(s):  
Low Temperature ◽  
Sodium Chlorate ◽  
Gold Leaching ◽  
Gold Ore

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 HYPOCHLORITE GOLD LEACHING AN ALTERNATIVE TO CYANIDE TECHNOLOGY

2021 ◽  
Author(s):  
Vitaly Prokopenko ◽  
◽  
Volodymyr Chernenko ◽  
Pavlo Vorotytsky ◽  
Igor Volobaiev ◽  
...  
Keyword(s):  
Sodium Hypochlorite ◽  
Large Scale ◽  
Gold Mining ◽  
Native Gold ◽  
Sea Water ◽  
Surface Film ◽  
Energy Dispersive Spectrometer ◽  
Alternative Methods ◽  
Gold Dissolution ◽  
Gold Leaching

Traditional technologies of gold mining are exhausted due to the depletion of stocks of conditioned raw materials at functioning gold mining enterprises, in addition, the preservation or disposal of large-scale waste of these technologies requires significant financial costs for environmental protection measures. Recently, the search for alternative methods of gold leaching, which involve the use of non-toxic factors, but which in their physicochemical properties can compete with traditional levels, and especially with cyanides. The authors of this work investigated the mechanism and kinetics of the process of dissolving metallic gold in chloride-hypochlorite solutions and believe that alkali metal hypochlorites (first of all, sodium hypochlorite NaOCl, which is easily obtained by electrolysis from a solution of food’s salt NaCl, or from sea water) are a very promising replacement for cyanide-containing leachates. Two series of experiments were carried out to study sodium hypochlorite as a gold leaching agent using a traditional gold disk and finely dispersed native gold as dissolution objects. Found fundamental differences in methodological techniques when working with a traditional model object and native gold. The dependences of the dissolution rate on the solution pH, sodium hypochlorite concentration, and temperature are determined. Conditions of the gold surface passivation during its dissolution are discussed. The first-order rate constant of the gold dissolution 1 0,079 - 0,4030  ki  h at temperatures from 277 K to 304 K and others are calculated. The activation energy from the temperature dependence of the rate constants (40,3 kJ/mol) evidences a diffusion-kinetic control of the gold dissolution. Electron microscopy (using electron probe scanning on an energy dispersive spectrometer) of native gold particles revealed foreign inclusions - adsorbed mineral particles of calcite (CaCO3) and, presumably, a surface film consisting of aluminum oxide (Al2O3), which create a significant obstacle to the contact of leaching agents with the surface of the target gold grains. Quantitative data on the composition of surface adsorption films, formed by model gold electrode dissolution products, are obtained using atomic adsorption spectroscopy.

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