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Journal: 

Issue Info: 
  • Year: 

    2004
  • Volume: 

    38
  • Issue: 

    4 (86)
  • Pages: 

    573-580
Measures: 
  • Citations: 

    0
  • Views: 

    964
  • Downloads: 

    0
Keywords: 
Abstract: 

The aim of the present work is to assess the compatibility of Sarcheshmeh molybdenite concentrate with native bacteria of the area. The strain of thiobacillus ferrooxidans was isolated from Sarcheshmeh mine drainage and the test work were performed in shake flasks. Effect of increasing pulp density from 1 to 5%, changing the culture medium from 9K to Norris and addition of surfactant Tween 80 on the performance of the Bioleaching was investigated. The results were compared to the chemical leaching process. It was revealed that Mo dissolution in Bioleaching of molybdenite was 6 times greater than chemical leaching. It was also found that thiobacillus ferrooxidans was able to leach pyrite and copper sulfide at higher rate compared to molybdenite, and consequently reduced the Fe and Cu content of molybdenite concentrate. Application of Norris culture medium or addition of Tween 80 to 9K medium for dissolution of Cu and Fe content of molybdenite can reduce the time of Bioleaching and its process cost.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    8
Measures: 
  • Views: 

    178
  • Downloads: 

    137
Abstract: 

IN THIS RESEARCH THE SPENT NI-CD AND NIMH BATTERIES WERE CHOSEN AMONG ALL KINDS OF MUNICIPAL WASTE FOR Bioleaching PROCESS AND EXTRACTING THEIR HEAVY METALS. THE Bioleaching PROCESS OF NICKEL, CADMIUM AND COBALT FROM NI-CD AND NIMH BATTERIES WAS DONE USING ACIDITHIOBACILLUS FERROOXIDANS KNOWN AS A RESISTANT STRAIN FOR Bioleaching. THE ADAPTATION PROCESS WAS SUCCESSFULLY DONE AND THE SOLID TO LIQUID RATIO WAS REACHED TO 10 G/L (BATTERY POWDER WEIGHT PER VOLUME OF MEDIUM). A BOX-BEHNKEN DESIGN OF RESPONSE SURFACE METHODOLOGY (RSM) WAS USED TO INVESTIGATE THE EFFECTS OF THREE FACTORS INCLUDING INITIAL PH, POWDER SIZE AND INITIAL FE+3 CONCENTRATION ON THE METALS RECOVERY PERCENT. ACCORDING TO THE RESULTS OBSERVED THROUGH STATISTICALLY DESIGNED EXPERIMENTS WE TRIED TO EVALUATE THE EFFECTS OF THREE FACTORS ON THE RECOVERY EFFICIENCY OF NICKEL, CADMIUM AND COBALT Bioleaching AND THE INTERACTIONS BETWEEN VARIABLES THAT WAS NOT POSSIBLE WITHOUT USING DESIGNED EXPERIMENTS. UNDER SPECIFIED CONDITIONS RECOVERY AMOUNT UP TO 100 PERCENT WAS OBSERVED FOR THREE METALS SEPARATELY. FOR NICKEL AND COBALT, DECREASING INITIAL PH AND PARTICLE SIZE AND INCREASING INITIAL FE+3 CONCENTRATIONS LED TO MAXIMUM YIELD OF RECOVERY FOR EACH METAL. WHILE THE RESULTS FOR CADMIUM SHOWED ITS DISTINCT BEHAVIOR AS CONTRASTED WITH THE TWO OTHER METALS.IT PROVES THE NECESSITY OF EXTRACTING OF THE METAL CADMIUM IN A SEPARATE STEP TO ACHIEVE THE MAXIMUM RECOVERY OF THE METAL. FOR SIMULTANEOUS EXTRACTION OF METALS WE OPTIMIZED THE PROCESS. THE OPTIMUM POINTS FOR FACTORS WERE OBTAINED AS INITIAL PH OF 1, PARTICLE SIZE OF 62 MICRONS AND INITIAL FE+3 CONCENTRATIONS OF 9.7 G/L. IN SUCH OPERATING CONDITION RECOVERY PERCENT OF 85.6 FOR NICKEL, 66.1 FOR CADMIUM AND 90.6 FOR COBALT WERE OBTAINED.

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Issue Info: 
  • Year: 

    2009
  • Volume: 

    1
  • Issue: 

    1
  • Pages: 

    57-65
Measures: 
  • Citations: 

    0
  • Views: 

    2540
  • Downloads: 

    0
Abstract: 

In recent years, bacterial leaching of copper from low grade chalcopyritic ores has been adverted very much. Different parameters such as the type of microorganisms, pH, temperature have a direct or indirect influence on the Bioleaching efficiency of sulfide minerals. Therefore, the main objective of this study was to quantify the potential of thermophile microorganisms for copper recovery from low-grade chalcopyritic ores. Using a representative chalcopyritic low grade copper ore from National Iranian Copper Company with a total copper grade of about 0.344% (CuFeS2= 0.78%), and two different thermophile bacteria, several Bioleaching tests were conducted. The final results of lab -tests show the potential of extremely thermophiles for Bioleaching of copper from this type of low grade ores is higher than moderate thermophiles. At optimum temperature, pH and Fe2+/ Fe3+ ratio, the average copper recovery from low grade ore with extremely them10philes is up to 17% higher than that with moderate thermopiles.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    30
  • Issue: 

    4 (60)
  • Pages: 

    71-79
Measures: 
  • Citations: 

    1
  • Views: 

    489
  • Downloads: 

    529
Abstract: 

This study deals with Bioleaching of the low grade uranium ore of Saghand mine in Iran using a mixed culture of mesophilic bacteria (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans). Experiments were carried out in shaking flask examining the effect of temperature, initial ferrous ion concentration, pulp density and particle size.Variations of pH, Eh, ferrous ion concentration, cells growth and uranium extraction were monitored. The highest rates of leaching and extraction were obtained at 35oC, 2.5% (w/v) pulp density, 4g/l ferrous ion and -106mm particle size.

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    7
  • Issue: 

    2
  • Pages: 

    3-16
Measures: 
  • Citations: 

    0
  • Views: 

    10
  • Downloads: 

    0
Abstract: 

Abstract

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Issue Info: 
  • Year: 

    2005
  • Volume: 

    4
Measures: 
  • Views: 

    182
  • Downloads: 

    60
Keywords: 
Abstract: 

The effects of mineral paricle size on the copper Bioleaching by Acidithiobacilus have been studied. Increasing the particle size from 0.15 mm to 3.4 mm enhanced the copper recovery from 51% to 93%. While the copper recovery of finely ground particles (<0.15 mm) was 76%. Also increasing the particle size between 3.4-6 mm adversely influenced the activity of bacteria and copper recovery of this fraction was 70%.

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Issue Info: 
  • Year: 

    2010
  • Volume: 

    2
  • Issue: 

    1
  • Pages: 

    23-35
Measures: 
  • Citations: 

    0
  • Views: 

    1882
  • Downloads: 

    0
Abstract: 

The main objective of this research was to study the Bioleaching of Sarcheshmeh chalcopyrite copper concentrate by mixed iron- and sulfur- oxidizing bacteria. Experiments were designed using a full factorial design program. The effects of temperature, pH, nutrient medium and silver ions on the iron and copper recovery from chalcopyrite concentrate as well as on the cell concentration were considered. The experiments were carried out at a pulp density of 10% (w/v) using shake flasks in incubator (150 rpm) for 30 days. Several models have been developed between the target variables and relevant parameters by means of variance analysis using the Design-Expert software. It was found that the maximum copper recovery can be achieved under the following optimum conditions: T=50°C, initial pH=1.8, nutrient medium=Norris, silver concentration, 30 mg/L.

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Journal: 

JOURNAL OF BIOSAFETY

Issue Info: 
  • Year: 

    2020
  • Volume: 

  • Issue: 

  • Pages: 

    61-70
Measures: 
  • Citations: 

    0
  • Views: 

    418
  • Downloads: 

    127
Abstract: 

Environmental pollution of heavy metals and plastics has been a great challenge of the last century. E-wastes increase heavy metals and plastics concentration in the environment. These toxic substances are a threat to organisms. So their removal from the environment seems necessary. There are different disposal methods like landfilling and incineration, which cause a great deal of damage to the environment. On the other hand, the need for precious metals recovery like gold and silver from e-waste makes recycling necessary. Nevertheless, these methods are generally expensive. So applying a new alternative is required. The purpose of this paper is to introduce Bioleaching as an alternative to conventional disposal and recycling methods. This method is used to remove the heavy and toxic metals in order to produce metallic nanoparticles. Then the application of nanoparticles in wastewater treatment and microplastics degradation is mentioned. The conversion of insoluble metals to soluble ones by microorganisms is called Bioleaching. Bacteria like Chromobacterium violaceum, Pseudomonas species, Sulfobacillus thermosulfidooxidans, and Acidiphilium acidophilum bioleach gold, silver, nickel, and copper of electronic wastes. There are different fungi like Aspergillus niger, Penicillium simplicissimum, Aspergillus fumigatus, and Aspergillus flavus that generate organic acid to leach out copper, lead, nickel, and aluminum. Morganella produces copper nanoparticles from wastes. Factors like microorganisms, particle sizes, temperature, and pH affect the Bioleaching process. Bioleaching is a substitution for recycling methods of electronic wastes. Wastewater treatment and photocatalytic degradation of microplastics are two critical applications of produced nanoparticles.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    2
  • Issue: 

    7
  • Pages: 

    55-61
Measures: 
  • Citations: 

    0
  • Views: 

    5398
  • Downloads: 

    0
Abstract: 

Background and Objective: Bioleaching is an economic process in which by using proper bacteria. One of the most important bacteria in this field is Acidithiobacillus ferrooxidan s. This bacterium has an optimum growth in temperature interval 25-35 degrees centigrade and it has no desirable growth in lower than 20oC temperature. The main purpose of this research is to adapt these bacteria in lower temperatures, so that Bioleaching process can be performed in all seasons of year including cold seasons.Materials and Methods: In this research, At.ferrooxidans is extracted from Pregnant leaching solution (PLS) of Sarcheshmeh copper mine and inoculated in TK and 9K media in 30°C. Then in order to adapt ofAt.ferrooxidans in low temperatures, this bacteria was enriched gradually at temperatures 25, 22, 18, 15, 12 and 4°C. In order to ensure the viability of bacteria at low temperatures and performing Bioleaching process, the growth of At.ferrooxidans and ferric iron concentrations was measured by a spectrophotometer. The concentration of Cu (II) has been measured by Neocuprion at that temperature. In order to confirm At.ferrooxidans growth at 4oC extracellular proteins was measured by Bradford methods after six days. DNA of At.ferrooxidans strain has been extracted and region genes of 16SrDNA were amplified by PCR and gene sequencing was done.Results: At.ferrooxidans has logarithmic growth at low temperatures such as 25, 22, 18, 15, 12 and 4 °C and is able to oxidize ferrous iron to ferric iron in Bioleaching process and release Cu II in soluble form. It is shown that bacteria has the best growth at 25oC after 18 days and the rate of growth decrease with temperature reduction. Comparing the results of nucleotide sequence superior strains with the related strains showed that the bacteria is Acidithiobacillus ferrooxidans and was named as AL strain.Conclusion: At.ferrooxidans is able to adapt and perform Bioleaching at low temperatures. Thus, according to the results, the process of iron oxidation and Bioleaching at low temperatures is possible and precious metals such as gold and copper can be extracted at low temperatures.

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Issue Info: 
  • Year: 

    2013
  • Volume: 

    9
Measures: 
  • Views: 

    135
  • Downloads: 

    63
Abstract: 

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