Investigation of Controlled Redox Potential with Pyrite during Chalcopyrite Bioleaching by Mixed Moderately Thermophiles

2017 ◽  
Vol 262 ◽  
pp. 281-284
Author(s):  
Xiao Tao Huang ◽  
Jun Wang ◽  
Hong Bo Zhao ◽  
Min Gan ◽  
Rui Liao ◽  
...  
Keyword(s):  
Redox Potential ◽  
Ferrous Ion ◽  
Copper Extraction ◽  
Ferrous Ions ◽  
Sem Images ◽  
Leptospirillum Ferriphilum ◽  
Acidithiobacillus Caldus ◽  
High Copper ◽  
Constant Ph

Various methods of controlling redox potential (ORP) with electrochemical bioreactor and others have been investigated to increase copper extraction of chalcopyrite in bioleaching,but less attention has been paid to reducing ferric to ferrous ions. Therefore, in this work, the redox potential of chalcopyrite bioleaching system in the presence of mixed moderately thermophiles containing Leptospirillum. ferriphilum,Acidithiobacillus. caldus and Sulfobacillus.thermosulfidooxidans has been controlled by pyrite. It was found that at a constant pH of 2.0, the addition of pyrite can reduce ferric to ferrous ion to a large extent, and the lower ORP values can be obtained. Bioleaching experiments indicated that the time for adding pyrite caused different bioleaching behaviors of chalcopyrite. The high copper extraction can be obtained by added pyrite at a low ORP values (<420 mV vs. Ag/AgCl). The XRD tests and SEM images showed that the amounts of formed jarosite increased as the pyrite addition, and the loose and porous jarosite can be found at low ORP values.

Adhesion of Acidithiobacillus Caldus and Leptospirillum Ferriphilum on Pyrite and their Effect on Surface Properties of Sulfide Minerals

2009 ◽  
Vol 71-73 ◽  
pp. 449-452
Author(s):  
G. Gu ◽  
Li Jun Su ◽  
Guan Zhou Qiu ◽  
Y. Hu
Keyword(s):  
Surface Properties ◽  
Isoelectric Point ◽  
Sulfide Minerals ◽  
Ferrous Ion ◽  
Bacterial Cells ◽  
Leptospirillum Ferriphilum ◽  
Acidithiobacillus Caldus ◽  
Ft Ir ◽  
Bacterial Adsorption ◽  
Strong Ability

Acidithiobacillus caldus and Leptospirillum ferriphilum cells grown in different energy substances (ferrous ion, sulfur and pyrite) were used. The adhesion of A. caldus and L. ferriphilum cells on pyrite and their effect on pyrite surface properties were studied by adsorption, zeta-potential and FT-IR methods, and the corrosion images of pyrite interaction with bacteria were examined using atomic force microscopy. Research showed that pyrite isoelectric point (IEP) after interaction with bacterial cells shifted towards cells isoelectric point, and the shift degree in case of interaction with A. caldus was observed to be much more pronounced than for interaction with L. ferriphilum, which can be due to higher affinity of A. caldus towards pyrite. The FT-IR spectra of pyrite treated with bacterial cells revealed the presence of the cell functional groups signifying cells adsorption. Although the adsorption density of A. caldus on pyrite was higher than that of L. ferriphilum, L. ferriphilum with strong ability to oxidize ferrous ion showed better leaching efficiency than A. caldus with strong ability to oxidize sulfur for pyrite leaching. The results demonstrated that more important of indirect action (L. ferriphilum) than direct action (A. caldus) on pyrite.Introduction Bacterial adsorption to minerals is an initial step in bacterial leaching for metal recovery [1]. It has been reported that bacterial adhesion is dependent not only on the biochemical properties of the organism but also on the interfacial properties of the various interfaces existing in a bioleaching system[2].The bacteria-mineral interactions result in the changes of their surface properties. The elucidation of their alternate will be beneficial for bioleaching processes. Both Acidithiobacillus caldus and Leptospirillum ferriphilum are known for their ability to inhabit acidic environments and derive energy from oxidation of inorganic substances with natural occurrence in ore deposits and acid mine drainage and high affinity towards sulfide minerals [3-5]. In this work, the alterations of surface properties of pyrite after interaction with L. ferriphilum and A. caldus are studied, and the changes in surface properties caused by bacterial adsorption are discussed with reference to bioleaching behavior of pyrite.

Investigation of Intermediates Evolutions during Bornite Bioleaching by Mesophilic Mixed Bacteria

2017 ◽  
Vol 262 ◽  
pp. 159-163
Author(s):  
Xing Xing Wang ◽  
Ming Hao Hu ◽  
Xiao Tao Huang ◽  
Rui Liao ◽  
Hong Bo Zhao ◽  
...  
Keyword(s):  
Redox Potential ◽  
Photoelectron Spectroscopy ◽  
Dissolution Process ◽  
Surface Species ◽  
X Ray Diffraction ◽  
Xps Spectra ◽  
X Ray ◽  
Leptospirillum Ferriphilum ◽  
Acidithiobacillus Caldus ◽  
Mixed Bacteria

In this study, bioleaching experiments, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were conducted to investigate the intermediates and surface species of bornite leached by mesophilic mixed bacteria of Leptospirillum. ferriphilum and Acidithiobacillus. caldus. Bioleaching experiments results showed that the mixed bacteria induced higher redox potential and significantly increased the copper extractions. In the presence of mesophilic mixed bacteria, bornite bioleaching was not inhibited by jarosite and S8. The evolution of intermediates during bornite dissolution was proposed: Cu5FeS4→ Cu9Fe9S16→CuFe2S3→CuS→Cu2+, the presence of mesophilic mixed bacteria accelerated the dissolution process. XPS spectra showed that the Cu was existed as Cu(I) species in different period, and confirmed that the presence of polysulfide and jarosite.

scholarly journals Effects of Fe+2 and Fe+3 in Pretreatment and Leaching on a Mixed Copper Ore in Chloride Media

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 866
Author(s):  
María E. Taboada ◽  
Pía C. Hernández ◽  
Aldo P. Padilla ◽  
Nathalie E. Jamett ◽  
Teófilo A. Graber
Keyword(s):  
Chloride Concentration ◽  
Solution Concentration ◽  
Copper Extraction ◽  
Curing Time ◽  
Ferrous Ions ◽  
Copper Ore ◽  
Second Stage ◽  
Acid Consumption ◽  
Nacl Concentration ◽  
Leaching Solution

A study of the pretreatment stage and subsequent leaching of a mixed copper ore with different chloride solutions containing iron was carried out. The first stage considered pretreatment tests to decide the best conditions. Two levels of each factor were analyzed, 20 and 50 kg/t of NaCl, 17 and 25 kg/t of H2SO4, 0 and 25 kg/t of Fe2(SO4)3·9.2H2O, 0 and 25 kg/t of Fe2SO4·7H2O, and a curing time of 15 and 30 days. The results showed a significant effect of NaCl and curing time on the extraction, and less effect was found with the variation of acid and iron salts. The second stage included column leaching using a solution with 0.5 g/L of Cu+2, 80 g/L of Cl−, 10 g/L of H2SO4, and variable concentrations of ferric and ferrous ions (0 and 2 g/L). The best copper extraction of 80.2% was found considering a pretreatment of 30 days, 25 kg/t of H2SO4, 50 kg/t of NaCl, and a leaching solution concentration described previously with 2 g/L of Fe+2. The results showed the leaching of all copper oxide species and 20% of the copper sulfide species. In addition, there was a reduction in the acid consumption as the resting time increases. Furthermore, to evaluate a possible decrease in time and acid in pretreatment and chloride in leaching, tests including 10 and 25 kg/t of H2SO4 and 1, 15, and 30 days of curing and a diminution of the NaCl concentration to 20 g/L (content from seawater) were executed. The results showed a significant effect on curing time below 15 days. Furthermore, the slight influence of the decrease of acid on copper extraction gives cost reduction opportunities. The diminution of chloride concentration (80 to 20 g/L) in leaching solution decreases the extraction from 79% to 66.5%. Finally, the Mellado leaching kinetic model was successfully implemented.

scholarly journals Exploring Coupled Redox and pH Processes with a Force Field-Based Approach: Applications to Five Different Systems

2020 ◽  
Author(s):  
Vinicius Cruzeiro ◽  
Gustavo Troiano Feliciano ◽  
Adrian Roitberg
Keyword(s):  
Force Field ◽  
Redox Potential ◽  
Desulfovibrio Vulgaris ◽  
Cytochrome C3 ◽  
Computational Tools ◽  
Redox States ◽  
Computational Performance ◽  
Redox Active ◽  
Constant Ph ◽  
Experimental Findings

Coupled redox and pH-driven processes are at the core of many important biological mechanisms. As the distribution of protonation and redox states in a system is associated with the pH and redox potential of the solution, having efficient computational tools that can simulate under these conditions become very important. Such tools have the potential to provide information that complement and drive experiments. In previous publications we have presented the implementation of the constant pH and redox potential molecular dynamics (C(pH,E)MD) method in AMBER and we have shown how multidimensional replica exchange can be used to significantly enhance the convergence efficiency of our simulations. In the current work, after an improvement in our C(pH,E)MD approach that allows a given residue to be simultaneously pH- and redox-active, we have employed our methodologies to study five different systems of interest in the literature. We present results for: capped tyrosine dipeptide, two maquette systems containing one pH- and redox-active tyrosine (α3Y and peptide A), and two proteins that contain multiple heme groups (diheme cytochrome c from Rhodobacter sphaeroides and Desulfovibrio vulgaris Hildenborough cytochrome c3). We show that our results can provide new insights into previous theoretical and experimental findings by using a fully force field-based and GPUaccelerated approach, which allows the simulations to be executed with high computational performance.

scholarly journals THE RATE CONSTANT OF THE REACTION BETWEEN FERROUS IONS AND HYDROGEN PEROXIDE IN ACID SOLUTION

1957 ◽  
Vol 35 (5) ◽  
pp. 428-436 ◽  
Author(s):  
T. J. Hardwick
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Solution ◽  
Sulphuric Acid ◽  
Acid Concentration ◽  
Rate Constant ◽  
Perchloric Acid ◽  
Ferrous Ion ◽  
Ferrous Ions ◽  
Bimolecular Rate Constant

Identical values of the bimolecular rate constant of the ferrous ion – hydrogen peroxide reaction were obtained from intercomparisons of the methods previously used in following this reaction. In perchloric acid the bimolecular rate constant is unaffected by acid concentration; in sulphuric acid it increases slightly in acid concentrations above 10−2N. The results agree with and explain the differences between those obtained by Baxendale and by Dainton, but are only in marginal agreement with those recently reported by Weiss.

2,2î-Bipyridine Catalyzed Bleaching of Cotton Fibers with Peracetic Acid

1988 ◽  
Vol 58 (4) ◽  
pp. 198-210 ◽  
Author(s):  
James W. Rucker ◽  
David M. Cates
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Peracetic Acid ◽  
Metal Ion ◽  
Solution Treatment ◽  
Transition Metal Ions ◽  
Ferrous Ion ◽  
Cotton Fibers ◽  
Lauryl Sulfate ◽  
Ferrous Ions

Peracetic acid can be catalyzed to bleach cotton fibers at temperatures as low as 30°C by incorporating 2,2î-bipyridine in the bleach solution. Treatment of the fibers with HCl prior to bleaching reduces bleaching effectiveness by removing trace transition metal ions from the fibers. Sorption of individual ions (Cr+3 Mn+2, Fe+2, Fe+3 Co+2, Ni+2, Cu+2, and Zn+2) by HCl treated cotton fibers prior to bleaching indicates that the ferrous ion produces the greatest catalytic effect, and it is only effective when the metal ion is in the fiber as opposed to in solution. Ferrous ions in the fibers sorb 2,2î-bipyridine from solution to form the tris-2,2î-bipyridine ferrous ion complex that is associated with the fibers, and it is the trischelate associated with the fibers that catalyzes bleaching. The effects of pH, temperature, and concentrations of 2,2î-bipyridine, sodium lauryl sulfate, and transition metal ions (in the fibers and in solution) on bleaching effectiveness and peracetic acid decomposition have been studied, and a bleaching mechanism is proposed.

On-Line Measuring Principle of Ferrous Ion in Fluxing

2010 ◽  
Vol 34-35 ◽  
pp. 1810-1815
Author(s):  
An Du ◽  
Rui Na Ma ◽  
Yong Zhe Fan ◽  
Xiao Ming Cao ◽  
Shi Jie Li ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Linear Equations ◽  
Automatic Detection ◽  
Ferrous Ion ◽  
Spectral Absorption ◽  
Ferrous Ions ◽  
Micro Pump ◽  
On Line

A spectral absorption of the ferrous ion in fluxing was investigated in this paper due to the significant effect of ferrous ion on the quality of hot-dip galvanizing production. Based on analysis of spectrophotometry, an automatic detection equipment of ferrous ions is developed according to its special characteristics. On-line measuring of ferrous ion in fluxing of the hot-dip galvanizing is realized by the micro-pump and the equipment. Results show that the lowest limit to be detected is 0.1 g/L, measuring errors are less than 0.05 g/L, the linear equations of the absorption and concentration of the ferrous ions shows a good correlation coefficient which is 0.99995 when the ferrous ions concentration is between 0.1g/L and 10g/L in fluxing.

scholarly journals Mesophilic leaching of copper sulphide sludge

2009 ◽  
Vol 74 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Vladimir Cvetkovski ◽  
Vesna Conic ◽  
Milovan Vukovic ◽  
Milena Cvetkovska
Keyword(s):  
Residue Analysis ◽  
Copper Recovery ◽  
Copper Extraction ◽  
Sulphide Mineral ◽  
Copper Sulphide ◽  
X Ray Diffraction ◽  
Ferrous Ions ◽  
Extraction Curve ◽  
Straight Line ◽  
Bioreactor System

Copper was precipitated using a sodium sulphide solution as the precipitation agent from an acid solution containing 17 g/l copper and 350 g/l sulphuric acid. The particle size of nearly 1 ?m in the sulphide sludge sample was detected by optical microscopy. Based on chemical and X-ray diffraction analyses, covellite was detected as the major sulphide mineral. The batch bioleach amenability test was performed at 32?C on the Tk31 mine mesophilic mixed culture using a residence time of 28 days. The dissolution of copper sulphide by direct catalytic leaching of the sulphides with bacteria attached to the particles was found to be worthy, although a small quantity of ferrous ions had to be added to raise the activity of the bacteria and the redox potential of the culture medium. Throughout the 22-day period of the bioleach test, copper recovery based on residue analysis indicated a copper extraction of 95 %, with copper concentration in the bioleach solution of 15 g/l. The slope of the straight line tangential to the exponential part of the extraction curve gave a copper solubilisation rate of 1.1 g/l per day. This suggests that a copper extraction of 95 % for the period of bioleach test of 13.6 days may be attained in a three-stage bioreactor system.

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