Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect
Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect Mechanisms via Thiosulfate or via Polysulfides and Sulfur Schippers, Axel; Sand, Wolfgang; Abstract. Publication: Applied and Environmental Microbiology. Pub Date: January 1999 DOI: 10.1128/AEM.65.1.319-321.1999 ...
Bioleaching: A microbial process of metal recovery; A review
The present review describes the historical development and mechanisms of bioleaching, which has shown commercial application of the process and, concurrently, details pertaining to the key microorganisms involved in these processes have been described. The present review describes the historical development and mechanisms of …
The Indirect Mechanism of Bacterial Leaching
The indirect mechanism of bacterial leaching, which is a combination of these two sub-processes, is able to account for the shape of the reaction curve obtained from bacterial leaching experiments. It is also shown that even at very low concentrations of iron in solution the indirect mechanism may be the dominant pathway in bacterial …
Microbial leaching for valuable metals harvesting
The metals present in sulfide minerals are liberated by direct and indirect bacterial leaching mechanisms. Direct mechanism of microbial leaching Direct …
Comparison of three different bioleaching systems for Li
The study describes the bioleaching of lithium from lepidolite using three different biological systems—acidophilic bacteria, microscopic fungus and yeasts. The …
Progress in bioleaching: fundamentals and mechanisms of …
Schippers A, Sand W. Bacterial leaching of metal sulfides proceeds by two indirect mechanisms via thiosulfate or via polysulfides and sulfur. Appl Environ Microbiol. 1999; 65 :319–321.
Progress in bioleaching: fundamentals and mechanisms of bacterial …
The recovery of heavy metals by an application of microorganisms is now a worldwide established biotechnological process. Metals for which this technique is mainly employed include copper, cobalt, nickel, zinc, and uranium. ... Sand W, Gehrke T, Jozsa PG, Schippers A (2001) (Bio)chemistry of bacterial leaching—direct vs. indirect …
Indirect Carbonation by a Two-Step Leaching Process Using …
Indirect carbonation as an efficient CO2 sequestration strategy has received extensive attention in recent years. This study proposes a two-step leaching indirect carbonation process using NH4Cl and CH3COOH in order to combine the advantages of the two leaching agents to obtain a better experimental outcome. The experimental …
Microbial leaching for valuable metals harvesting
Mostly bacteria and fungi can be engaged for this purpose. The bacterial assisted microbial leaching is called "bacterial leaching" and the term "fungal leaching" is applied for microbial leaching supported by fungi. Figure 1 shows some of the most commonly used micro-organisms in the microbial leaching process. Depending upon …
Progress in bioleaching: fundamentals and mechanisms of …
Understanding and application of bacterial leaching of metal sulfides has developed rapidly in the course of the last two decades. The mobilization of metal …
Progress in bioleaching: fundamentals and mechanisms of
Schippers A, Sand W (1999) Bacterial leaching of metal sulfides proceeds by two indirect mechanisms via thiosulfate or via polysulfides and sulfur. Appl Environ …
Microbial Leaching (Bioleaching, Biomining)
Microbial leaching is the process by which metals are dissolved from ore bearing rocks using microorganisms. For the last 10 centuries, microorganisms. Support us, Buy us a coffee ... Indirect Bacterial Leaching In indirect bacterial leaching microbes are not in direct contact with minerals but leaching agents are produced by microorganisms ...
Bio Hydrometallurgical Technology, Application and Process …
2. Mechanisms of bioleaching. The two majorly known mechanism in bacterial leaching are direct mechanism (involves physical contact of the organism with the insoluble sulphide) or hypothesized enzymatic reaction taking place between an attached cell and the underlying mineral surface which is independent of indirect …
(Bio)chemistry of bacterial leaching—Direct vs. indirect …
The maximum Al leaching percentage (54.5%) was achieved using biogenic acids with stationary-phase bacteria at a TWC pulp density of 5% w/v whereas bacteria-free biogenic acid (23.4%), biogenic ...
Bioleaching: metal solubilization by microorganisms
To keep enough iron in solution the chemical oxidation of metal sulfides must occur in an acid environment below pH 5.0. The ferrous iron arising in this reaction can be reoxidized to ferric iron by T. ferrooxidans or L. ferrooxidans and as such can take part in the oxidation process again. In indirect leaching the bacteria do not need to be in …
Sulfur chemistry in bacterial leaching of pyrite | Applied and
The data indicate that thiosulfate, trithionate, tetrathionate, and disulfane-monosulfonic acid are key intermediate sulfur compounds in oxidative pyrite degradation. A novel (cyclic) leaching mechanism is proposed which basically is indirect.
(Bio)chemistry of bacterial leaching
The microbial leaching process was evaluated for the treatment of synthetic sediments contaminated with cadmium and nickel sulfides to compare metal solubilization in sediment inoculated with Acidithiobacillus ferrooxidans -inoculated sediments to that in sterile control sediment, indicating that indirect non-contact leaching by the products of …
Progress in bioleaching: fundamentals and mechanisms of
In general, leaching bacteria seem to grow attached to the surfaces of mineral sulfides. In case of not limiting surface space, some microorganisms with good attachment capabilities to mineral surfaces exhibit attachment of up to 80–90% of the planktonic cells within less than one day (Gehrke et al. 1998; Harneit et al. 2006).It is …
Bioleaching review part A: | Applied Microbiology and
Bioleaching of metal sulfides is caused by astonishingly diverse groups of bacteria. Today, at least 11 putative prokaryotic divisions can be related to this phenomenon. In contrast, the dissolution (bio)chemistry of metal sulfides follows only two pathways, which are determined by the acid-solubility of the sulfides: the thiosulfate and …
Mechanisms of bioleaching: iron and sulfur oxidation by …
During the bioleaching process, microbes generate energy by oxidising sulfur and iron from sulfide minerals. The resulting oxidants attack the sulfide minerals, …
Bioleaching: A microbial process of metal recovery; A review
In the 'indirect' mechanism bacteria oxidize only dissolved iron (II) ions to iron (III) ions and the latter can then attack metal sulfides and then be reduced to iron (II) …
Microbial leaching of metals from sulfide minerals
Section snippets General description. Microbial leaching is an economical method for the recovery of metals from low-grade mineral ores. Two thousand years ago, microbial leaching of copper as copper sulfate from sulfide ores and recovery of metallic copper by 'cementation' was known both in Europe and China (Fossi, 1990): CuSO 4 …
(Bio)chemistry of bacterial leaching—direct vs. indirect bioleaching
The two different indirect oxidation mechanisms together with the role of the EPS have a fundamental importance for the debate about the "direct" or "indirect" mechanism of bacterial leaching. It becomes evident that a "direct", i.e. enzymatic attack, mechanism does not exist.
Direct versus indirect bioleaching
In practice, multiple patterns of bacterial leaching coexist, including indirect leaching, contact leaching and a recently discovered cooperative (symbiotic) leaching where 'contact' leaching bacteria are feeding so wastefully that soluble and particulate sulfide species are supplied to bacteria in the surrounding electrolyte. 1.
Bioleaching
Direct and indirect mechanisms are involved in sulfur based leaching process by bacteria leading to the formation of metal sulfides and its dissolution (Fig. 4). In direct leaching process, bacteria directly contact and react with metal sulfide and oxidize it to soluble metal sulfates like NiS, ZnS, CuS, etc.
Bioleaching: metal solubilization by microorganisms
In direct bacterial leaching, there is physical contact between the bacterial cell and the mineral sulfide surface, and the oxidation to sulfate takes place via several …
Direct versus indirect bioleaching
1.. IntroductionThe mechanism of bacterial leaching of sulfides has interested researchers for a long time [1], [2].While many parameters affecting the leaching process have been known as empirical factors, a more profound understanding of the heterogeneous mechanism of sulfide degradation has only gradually emerged as a …
Microbial leaching
According to equation 3, iron is dissolved through direct bacterial leaching. In addition to this leaching process performed only by micro-organisms, there is another process, 'indirect, bacterially supported leaching', which takes place slowly in the absence of microbes. The oxidation of pyrite can be used as an example.
Bacterial Leaching
is further confirmed by the leaching of synthetic sulphides free of iron, where only the direct attack of the bacteria can lead to leaching: CuS (covellite) + 202 --.CuS04, ZnS (sphalerite) + 20z -+ ZnS04 • Bacterial Leaching Techniques The two major techniques used in leaching are percolation and agitation leaching.
Direct versus indirect bioleaching
In practice, multiple patterns of bacterial leaching coexist, including indirect leaching, contact leaching and a recently discovered cooperative (symbiotic) leaching where 'contact leaching bacteria are feeding so wastefully that soluble and particulate sulfide species are supplied to bacteria in the surrounding electrolyte.