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Bioleaching (microbial leaching), being an economical and environmental friendly process, is investigated extensively for metal extraction from secondary solid wastes, viz., electronic wastes ...
4 Factors influencing bioleaching. The leaching effectiveness depends largely on the efficiency of the microorganisms and on the chemical and mineralogical composition of the ore to be leached. The maximum yields of metal extraction can be achieved only when the leaching conditions correspond to the optimum growth conditions of the bacteria ...
The continuous bioleaching of a sphalerite concentrate, assaying % Zn, % Pb, % S and % Fe with mesophile iron and sulphuroxidizing bacteria followed by chemical leaching of the ...
Further, the leaching data were analyzed using shrinking core model which revealed that the rate of leaching was inhibited by diffusion through product layer. Reaction kinetics is also to be contrasted with thermodynamics. Using Arrhenius law of thermodynamics, it was found that activation energy for Zn bioleaching reaction was kJ mol−1.
2. Heap Leaching. In this technique, the ore is arranged in large heaps. During heap leaching, an aqueous mixture of microorganisms is sprinkled over the leach pile. Then, the solution is collected and processed to help recover even more metal. 3. Insitu Leaching. The ore remains in its natural state while the leaching process takes place.
In an ultrasoundassisted bioleaching process for the recovery of Zn, Cu, and Co from black shale, one group of researchers achieved optimal leaching efficiencies of 92% Cu and 87% Zn and 71% Co, respectively, at a sonication time of 7 min with 15 d of pregrowth and 36 d of bioleaching. 20 In the bioleaching of printed circuit boards (PCBs ...
This work sought to integrate bioleaching and chemical leaching as a costeffective process to treat zinc sulphides. The continuous bioleaching of a sphalerite concentrate, assaying % Zn, % ...
It is assumed that chemical leaching by biogenic Fe3+ integrated into the processes of leaching of PCB''s may contribute to intensification of extraction of copper and other valuable metals from different secondary resources. ... Longterm objective is to study the peculiarities of bioleaching of secondary raw materials, reveal the role of ...
Bioleaching experiments were successfully performed in this medium to recover gold and copper from telecommunication printed circuit boards. The results of inductively coupled plasma (ICP) analysis confirmed that gold recovery peaked out at around 55% after 4 days, whereas copper recovery continued to increase for several more days, peaking out ...
Aug 15, 2020· In general, bioleaching is cleaner and safer for the environment than chemical processing. However environmental pollution with toxic products, like sulfuric acid from the pyrite leaching, and heavy metals is still possible. Another drawback of microbial leaching is the slow rate at which microbes work.
May 01, 2007· Considering bioleaching and chemical leaching as integrated processes, the overall leaching time is reduced as compared to that observed by Pani et al. (2003) for the complete bioleaching of ZnS; nevertheless the residence time is still relatively large. As a result, this route would be most suitable for small expansions in RLE plants, such as ...
In bioleaching of pyrite there is an initial chemical leaching where Fe 3+ oxidises the mineral: 4FeS 2 + 4Fe 2 (SO 4 ) 3 → 12Fe(SO 4 ) + 8S The ferrous sulphate and elemental sulphur formed is then oxidised with the aid of microbes according to the following reactions:
Mar 18, 2015· The aim of this research was to compare the efficiencies of microbial leaching and chemical leaching of As and heavy metals from mine tailings. A mixed culture of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans was used as a microbial lixiviant agent for microbial leaching, while sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) were used as the leachants for chemical leaching.
Jan 23, 2019· Bioleaching takes advantage of microbial activities to turn valuable but insoluble metal compounds into water soluble forms. Compared to chemical leaching, this technology has the advantages of being: (1) environmentally friendly, (2) low energy input and (3) low chemical cost.
Jul 14, 2020· S. Mithra Last Modified Date: July 14, 2020 . Bioleaching is the use of bacterial microorganisms to extract precious metals, such as gold, from ore in which it is an alternative to smelting or roasting, miners use bioleaching when there are lower concentrations of metal in ore and they need an efficient, environmentally responsible method to extract it.
Jul 01, 2012· de SOUZA A D, PINA P S, LEAO V A. Bioleaching and chemical leaching as an integrated process in the zinc industry [J]. Minerals Engineering, 2007, 20(6): 591–599. Article Google Scholar . HOANG J, REUTER M A, MATUSEWICZ R, HUGHES S, PIRET N. Top submerged lance direct zinc smelting [J]. Minerals Engineering, 2009, 22(9/10):742–751.
Souza AD, Pina PS, Lea˜o VA .2007. Bioleaching and chemical leaching as an integrated process in the zinc industry. Minerals Engineering Journal 20: 591–599. Svens K, Kerstiens K, Runkel M. 2003. Recent experiences with modern zinc processing technology. Erzmetall 56: 94–103.
Nov 01, 2015· Recently, a novel integrated bioleaching system with stable pHsilver ionchloride ion has been proposed to enhance bioleaching efficiency of chalcopyrite using mixed strains of Acidithiobacillus (Feng et al., 2013). Thorough this integrated system, the formation of S° and jarosite precipitation was largely minimized.
Biological leaching of fly ash from municipal waste incineration by Aspergillus niger was examined in batch cultures and compared with chemical leaching. A. niger grew in the presence of up to 10% (w/v) of fly ash in the medium. In the presence of fly ash A. niger produced gluconate, whereas in its absence citrate was produced. Variation of the fly ash concentration in the growth medium (one ...
This work investigated the effects of Fe3+, H+ and adsorbed leaching bacteria on the bioleaching of pentlandite. Collectively, an integrated model for the oxidation and decomposition of pentlandite was built to describe the behaviors of different components in a bioleaching system. Proton ions and ferric ions could promote the break and oxidation of NiS and FeS bonds.
Bioleaching has been discussed with copper, uranium, gold, silver and silica. Copper Leaching Throughout the world copper leaching plants have been widely used for many years. It is operated as simple heap leaching process or combination of both heap leaching and in situ leaching process. Dilute sulphuric acid (pH 2) is percolated down through ...
Chemical oxidation integrated into bioleaching of p yrite and chalcop yrite using immobil ized biomass Fig. 4. Rate of generation of Fe 2+ during chemical oxidati on of pyrite at dif ferent pulp ...
Mar 01, 2019· Bioleaching experiments with a mixed Acidithiobacillusculture were carried out in shake flasks as well as in column percolators with crushed and sieved sphaleriterich ore from a former mine in the German Harz sphalerite dissolution in the bioleaching assays was observed in contrast to the chemical leaching experiments.
Abstract: Chemical and biological leaching is practiced on a commercial scale for the mining of metals from ores. Although bioleaching is an environmentallyfriendly alternative to chemical leaching, one of the principal shortcomings is the slow rate of leaching which needs to be addressed.
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