Bioleaching Research Papers - Academia.edu (original) (raw)

Siderophores are a class of biogenic macromolecules that have high affinities for metals in the environment, thus could be exploited for alternate sustainable metal recovery technologies. Here, we assess the role of siderophores in the... more

Siderophores are a class of biogenic macromolecules that have high affinities for metals in the environment, thus could be exploited for alternate sustainable metal recovery technologies. Here, we assess the role of siderophores in the extraction and complexation of metals from an iron oxide-rich metallurgical processing residue and a low-grade primary Ni ore. Evaluation of the biological siderophore production by three pseudomonads, P. fluorescens, P. azotoformans and P. putida identified that P. putida could generate the highest siderophore yield, which was characterized as a hydroxamate and catecholate mixed-type pyoverdine PyoPpC-3B. Key physicochemical parameters involved in raw siderophore mediated metal extraction were identified using a fractional factorial design of experiments (DOE) and subsequently employed in purified PyoPpC-3B leaching experiments. Further targeted experiments with hydroxamate and catecholate functional analogues of PyoPpC-3B confirmed their marked abil...

In this study, we have investigated the bioleaching potential of a native strain of Acidithiobacillus ferrooxidans isolated from zinc and lead sulfide mines under varied ambient conditions of growth and substrate consumption. The effects... more

In this study, we have investigated the bioleaching potential of a native strain of Acidithiobacillus ferrooxidans isolated from zinc and lead sulfide mines under varied ambient conditions of growth and substrate consumption. The effects of intermittent irrigation, type of agglomeration, feed formulation in terms of acid, enriched salt solution, initial number of microorganism, and their interactions on the bioleaching of low-grade zinc sulfide ores (containing 5.78% zinc) on growth and biooxidation efficiency of the bacteria have been evaluated. Bioleaching capacities of the isolate were optimized by the utilization the Taguchi method (e-qualitic-4) for design of experiments. As a result, eight column bioreactors with 5.7 kg ore (100% <12 mm) capacity were fabricated. Through the analysis, continuous inoculation of the ores with the solution of A. ferrooxidans type and spraying a bacterial-rich solution into the agglomerator were found to be the most significant factors, whereas intermittent irrigation and interactions of parameters have less effect within the ranges investigated. The extraction of zinc was obtained under the optimal conditions more than 70% in 80 days, which is noticeable to compare with conventional bioleaching.

This investigation compares bacterial leaching to chemical leaching to solubilize copper from a copper containing ore of the new site Northern Qarashoshaq in Zhylandy (Kazakhstan) which is currently under commercial development. From... more

This investigation compares bacterial leaching to chemical leaching to solubilize copper from a copper containing ore of the new site Northern Qarashoshaq in Zhylandy (Kazakhstan) which is currently under commercial development. From ICP-OES analysis the bulk ore sample contains 1.5% of Cu and a trace level at 0.0024 % of Ag. Phase analysis shows the main copper containing minerals are covellite, сhalcocite, malachite, chrysocolla and chalcopyrite. According to X-ray diffraction analysis silver is mainly presented as jalpaite (Ag3CuS2) minerals. Copper leaching was carried out by acidophilic bioleaching for comparison with extraction by chemical methods involving the addition of sulfuric acid and Fe3+ or only sulfuric acid in flasks, as well as column leaching tests to simulate heap leaching. Ag was extracted by cyanidation methods again in flasks as well as column leaching tests. Results showed that copper extraction is up to 95% when using bioleaching in the flask, 83% in the case of Fe3+ with sulfuric acid and 76% for sulfuric acid. Furthermore, subsequent extraction of Ag reaches 97% for bioleaching and 92% for chemical leaching. Column bioleaching tests showed an 82.3% yield of copper after 70 days of the experiment and a 70% of silver, whereas for chemical leaching the yield of copper is 66.8% and silver is 51%. In conclusion this investigation demonstrated higher extraction for both copper and silver from the primary ore in the bioleaching sample compared to the chemical leaching sample. More silver was extracted in the bioleaching case as there was less copper remaining to compete for the cyanide anions.

Due to the rapidly evolving sophistication of the economy, the worldwide production of electronic waste is incre generation of e-waste is the high rate of obsolescence in the electronic market. This paper focuses on the recovery of base... more

Due to the rapidly evolving sophistication of the economy, the worldwide
production of electronic waste is incre
generation of e-waste is the high rate of obsolescence in the electronic market. This
paper focuses on the recovery of base and precious metals from e
years, an alternative approach, i.e., gre
considered based on the combination of safer chemical knowledge and the use of
microorganisms for metal mobilization from e
Chromobacteriumviolaceum, Pseudomonas aeruginosa and Pseud
fluorescens, have the ability to produce hydrocyanide acid. This indirect process of
using bacterial leaching to dissolve gold from minerals has achieved a highest
recovery rate of 73.2% (w/w). To date, 2
printed circuit boards have successfully leached up to 98.5% (w/w) of Cu, while the
recovery for gold is still relatively low level. Therefore, the use of the optimumconditions, the right mixed culture of bacteria, and the proper method will improve
the metal recovery and efficiency in future.

Fe 2+ oxidation by Acidithiobacillus ferrooxidans (At. ferrooxidans) under different solid contents by adding inert Al 2 O 3 powder was examined in rotating-drum and stirred-tank reactors. The results show that the bioactivity of At.... more

Fe 2+ oxidation by Acidithiobacillus ferrooxidans (At. ferrooxidans) under different solid contents by adding inert Al 2 O 3 powder was examined in rotating-drum and stirred-tank reactors. The results show that the bioactivity of At. ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al 2 O 3 powder, but the biooxidation rate of Fe 2+ decreases markedly from 0.23 g/(L·h) to 0.025 g/(L·h) with increasing the content of Al 2 O 3 powder from 0 to 50% (mass fraction) in the stirred-tank probably due to the deactivation of At. ferrooxidans resulting from the collision and friction of solid particles. The increase in Al 2 O 3 content has a little adverse effect on the bioactivity of At. ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors. The biooxidation rate of Fe 2+ in the rotating-drum is higher than that in the stirred-tank at the same content of Al 2 O 3 powder, especially at high solid content. The higher bioactivity of At. ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor, but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al 2 O 3 powder and sulfide minerals.

Biological formation of K + and NH 4 + jarosites. Raman and FTIR microspectroscopies to probe the whole ore chalcopyrite–bacteria interactions. Probing the matrix of the extracellular polymeric substances during the bioleaching process. a... more

Biological formation of K + and NH 4 + jarosites. Raman and FTIR microspectroscopies to probe the whole ore chalcopyrite–bacteria interactions. Probing the matrix of the extracellular polymeric substances during the bioleaching process. a b s t r a c t The whole ore chalcopyrite–bacteria interaction and the formation of the extracellular polymeric substances (EPS) during the bioleaching process by microorganisms found in the mine of Hellenic Copper Mines in Cyprus were investigated. Raman and FTIR microspectroscopies have been applied towards establishing a direct method for monitoring the formation of secondary minerals and the newly found vibrational marker bands were used to monitor the time evolution of the formation of covellite, and the K + and NH 4 +-jarosites from the chalcopyrite surfaces. The Raman data indicate that the formation of K +-jarosite is followed by the formation of NH 4 +-jarosite. The variation in color in the FTIR imaging data and the observation of the amide I vibration at 1637 cm À1 indicate that the microorganisms are attached on the mineral surface and the changes in the frequency/intensity of the biofilm marker bands in the 900–1140 cm À1 frequency range with time demonstrate the existence of biofilm conformations.

A comparison of the metabolic potential of 20 bioleaching microorganisms and their close relatives from the Eubacteria and Archaea kingdoms permits the prediction of inter- and intra-species physiological interactions (ecophysiology)... more

A comparison of the metabolic potential of 20 bioleaching microorganisms and their close relatives from the Eubacteria and Archaea kingdoms permits the prediction of inter- and intra-species physiological interactions (ecophysiology) during spatial and temporal changes that are known to occur within industrial bioleaching heaps. Genome analysis has allowed preliminary models to be built for genes and pathways involved in key processes such as nitrogen and carbon cycling, sulfur and iron uptake and homeostasis, extra-cellular polysaccharide biosynthesis, heavy metal resistance and energy metabolism. This paper will focus on the diverse ways that bioleaching microorganisms obtain carbon from their environment with a particular emphasis on elucidating how these processes might be expected to vary over space and time during the lifetime of a bioleaching operation. It is anticipated that this knowledge will improve our understanding of fundamental biological processes in extremely acidic...

The nature of the mineral–bacteria interphase where electron and mass transfer processes occur is a key element of the bioleaching processes of sulfide minerals. This interphase is composed of proteins, metabolites, and other compounds... more

The nature of the mineral–bacteria interphase where electron and mass transfer processes occur is a key element of the bioleaching processes of sulfide minerals. This interphase is composed of proteins, metabolites, and other compounds embedded in extracellular polymeric substances mainly consisting of sugars and lipids (Gehrke et al., Appl Environ Microbiol 64(7):2743–2747, 1998). On this respect, despite Acidithiobacilli—a ubiquitous bacterial genera in bioleaching processes (Rawlings, Microb Cell Fact 4(1):13, 2005)—has long been recognized as secreting bacteria (Jones and Starkey, J Bacteriol 82:788–789, 1961; Schaeffer and Umbreit, J Bacteriol 85:492–493, 1963), few studies have been carried out in order to clarify the nature and the role of the secreted protein component: the secretome. This work characterizes for the first time the sulfur (meta)secretome of Acidithiobacillus thiooxidans strain DSM 17318 in pure and mixed cultures with Acidithiobacillus ferrooxidans DSM 16786, identifying the major component of these secreted fractions as a single lipoprotein named here as Licanantase. Bioleaching assays with the addition of Licanantase-enriched concentrated secretome fractions show that this newly found lipoprotein as an active protein additive exerts an increasing effect on chalcopyrite bioleaching rate.