Zinc bioleaching from an iron concentrate using Acidithiobacillus ferrooxidans strain from Hercules Mine of Coahuila, Mexico (original) (raw)
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International Journal of …, 2006
A mesophilic iron oxidizing bacterium, Acidithiobacillus ferrooxidans, has been isolated (33°C) from a typical, chalcopyrite concentrate of the Sarcheshmeh copper mine in the region of Kerman located in the south of Iran. In addition, a thermophilic iron oxidizing bacterium, Sulfobacillus, has been isolated (60°C) from the sphalerite concentrate of Kooshk lead and zinc mine near the city of Yazd in the center point of Iran. Variation of pH, ferrous and ferric concentration on time and effects of some factors such as temperature, cell growth, initial ferrous concentration and pH on bioleaching of low-grade complex zinc-lead ore were investigated. The results obtained from bioleaching experiments indicate that the efficiency of zinc extraction is dependent on all of the mentioned variables; especially the temperature and initial Fe(II) concentration have more effect than other factors for these microorganisms. In addition, results show that the maximum zinc recovery was achieved using a thermophilic culture. Zinc dissolution reached 58% with Sulfobacillus while it was 51% with A. ferrooxidans at pH = 1.5, initial Fe(II) concentration = 7 and 9 g/L for A. ferrooxidans and Sulfobacillus, respectively, after 30 days.
Bioleaching of copper- and zinc-bearing ore using consortia of indigenous iron-oxidizing bacteria
Extremophiles : life under extreme conditions, 2018
Indigenous iron-oxidizing bacteria were isolated on modified selective 9KFe medium from Baiyin copper mine stope, China. Three distinct acidophilic bacteria were isolated and identified by analyzing the sequences of 16S rRNA gene. Based on published sequences of 16S rRNA gene in the GenBank, a phylogenetic tree was constructed. The sequence of isolate WG101 showed 99% homology with Acidithiobacillus ferrooxidans strain AS2. Isolate WG102 exhibited 98% similarity with Leptospirillum ferriphilum strain YSK. Similarly, isolate WG103 showed 98% similarity with Leptospirillum ferrooxidans strain L15. Furthermore, the biotechnological potential of these isolates in consortia form was evaluated to recover copper and zinc from their ore. Under optimized conditions, 77.68 ± 3.55% of copper and 70.58 ± 3.77% of zinc were dissolved. During the bioleaching process, analytical study of pH and oxidation-reduction potential fluctuations were monitored that reflected efficient activity of the bacte...
IntechOpen eBooks, 2023
The analysis of the variables, bacterial population, and oxidation-reduction potential (ORP) during the bioleaching of sulfide ores by a bacterial strain of Acidithiobacillus ferrooxidans, isolated from acid mine effluent, aims at the solubilization of copper and the liberation of the gold present in an ore containing more than 80% sulfides. It was studied at different pulp densities (1, 2, and 6%-W/V) and with a 9 k medium at different ferrous sulfate concentrations (0, 3, 6, 9, 12, and 15 g/L), keeping temperature and pH constant. The tests were carried out in three consecutive stages, starting with inoculum, whose cell content was 7.05x10 7 Cell/mL, then the strain with the highest population obtained in the previous stage was used, observing the variation in the periods of adaptation and growth. During the bioleaching of sulfide ores, in the first stage, the maximum bacterial population achieved was 4.75x10 7 Cell/mL in 24 days with 6 g/L ferrous sulfate, in the second stage, the maximum population was 6.30x10 7 Cell/mL without the addition of ferrous sulfate, and in the third stage, the bacterial population became 4.51x10 7 Cell/mL. The exponential characteristic growth of the population started at approximately 13, 8, and 3 days, respectively in each stage.
Bioleaching of low-grade copper ore using indigenous microorganisms
Investigations have been carried out on the iron oxidation rate of Acidithiobacillus ferrooxidans, the bacteria used in bioleaching process. It was observed that the regeneration time of the bacteria is reduced from 168 to 16 h by repeated subculturing, which in turn gave rise to higher iron oxidation rate thus increasing the kinetics of the process. This active strain was utilized for bioleaching of low-grade copper ore by varying two parameters namely, pH and pulp density. It was observed that around 30% of copper could be leached at an initial pH and pulp density of 2 and 20% (m/v) respectively.
Hydrometallurgy, 2004
This study investigates the bioleaching of the complex Pb/Zn ore/concentrate using mesophilic (at 30 jC), moderate (at 50 jC), and extreme thermophilic (at 70 jC) strains of acidophilic bacteria. The effects of bacterial strain, pH, iron precipitation, and external addition of Fe 2 + on the extraction of zinc were evaluated. The results have shown that the ore is readily amenable to the selective extraction of zinc and lead using the acidophilic strains of bacteria [i.e., majority of lead (>98%) reports to the residue]. Moderate thermophiles displayed superior kinetics of dissolution of zinc compared with the other two groups of bacteria. The pH was found to exert a profound effect on the leaching process controlling the bacterial activity and precipitation of ferric iron mainly as K-jarosite. The K + released presumably from the alteration of the silicate phases such as K-feldspar present in the ore appeared to promote the formation K-jarosite in moderately thermophilic leaching systems. The external addition of iron was shown to be required for the bacteria to efficiently drive the extraction of zinc from the bulk concentrate. These findings place the emphasis on the prime importance of ferric iron for the dissolution of zinc and of mineralogical properties (i.e., iron and silicate content) of an ore/concentrate to be treated via bioleaching processes. D
Zinc recovery during refractory ore biooxidation by an indigenous consortium
Two enrichment cultures (one iron oxidizing and one sulfur oxidizing) obtained froman acid mine drainagewere physiologically and molecularly characterized; the first of them showed 99% 16S rRNA gene sequence similarity with Leptospirillum ferrooxidans, while the sulfur oxidizing species was highly related to Acidithiobacillus ferrooxidans and Acidithiobacillus ferrivorans sequences although, unlike them, the species in the enrichment culture does not seem to be able to oxidize iron. The consortium constituted by both enrichment cultures achieved a successful biooxidation of Hualilan ore allowing the increase of gold recovery up to 96.4% in the best culture condition (low pulp density in 1 K medium). At the same time, this condition showed an effective zinc bioleaching (up to 86%) although the recovery was much higher in cultures with initially supplemented iron; kinetics studies suggested that the bioleaching rate in 1 K medium at low pulp densities is controlled by diffusion through a layer mainly constituted by jarosite (rather than sulfur)whichwas detected in X-ray diffraction diagrams. The recovery of zinc as a subproduct of the pretreatment to optimize gold recovery would also allowthe decrease of the metallic charge of the leachates fromthe biooxidation tanks which is an environmental advantage
Bioleaching of high grade Zn–Pb bearing ore by mixed moderate thermophilic microorganisms
In this research, the bioleaching mechanism of zinc and lead from high-grade Zn–Pb ore has been investigated. It is done by using mixed culture of iron and sulfur oxidizing moderate thermophilic bacteria at 45 C. Pulp density, initial pH and ferrous concentration were studied as influential parameters in bioleaching experiments. The optimum conditions were achieved at pulp density = 50 (g/L), initial pH = 1 and FeSO4.7H2O concentration = 75 (g/L) with 98.5% zinc recovery after 25 days treatment. Generally, an increase in ferrous concentration caused an improve zinc recovery, and an increase in initial pH and pulp density caused reduction in zinc recovery. However, in the test with optimum condition the lead dissolution was just 0.027% due to the lower Pb solubility. Furthermore, cadmium dissolution was 98% under optimum condition and results showed the cadmium dissolution was in direct proportion with zinc dissolution. Finally, 7.82% of arsenic and 8.52% of antimony dissolved during zinc bioleaching after 25 days treatment, both under above mentioned optimum condition.
Bioleaching of Mining Waste of Hindustan Zinc Limited, Udaipur
The research work presented in this paper is on a Biotechnological investigation for the recovery of zinc from mining waste i.e. Low grade ore Leaching Studies were carried out at different pH using mixed culture grown from mine water. Recovery of zinc in control set (without culture) was 8% in 37 days and at the same pH (1.6) with the culture of leaching bacteria, the recovery of zinc was 89%, whereas at pH 1.8 and 2.0 zinc recovery was 47% and 46% respectively. The best leaching of low grade ore was obtained at pH 1.6. From the results obtained during experimentation it is found that the recovery of zinc is not dependent only on the iron content in the solution because with the same content of iron there is a difference of recovery of zinc. It shows that both types of reaction mechanisms, direct & indirect are involved during leaching process.Keywords: Die materials, die wear, contact pressure, sliding distance, die wear test.
The effect of ferrous and ferric iron on sphalerite bioleaching with Acidithiobacillus sp
Minerals Engineering, 2005
Bioleaching has gained increased interest as an alternative for processing zinc sulfide ores without the generation of SO 2. The bioleaching of sphalerite with mesophile microorganisms at 1% pulp density has been studied. Batch experiments were carried out at 34°C and 200 rpm. The effects of pH, concentration of Fe(II), as well as the presence of Fe(III) in the zinc extraction were assessed. Fast zinc dissolution can be achieved working with Acidithiobacillus sp. The best pH for bioleaching is in the 1.75-2.00 range and the presence of Fe(III) has a strong influence in zinc extraction, increasing the rate of dissolution and does not adversely affect the growth of the Acidithiobacillus population.