Manganese Bioleaching Research Articles

Evaluation of manganese bioleaching and silver extraction in mining tailings by native bacteria using a flooded system

During the silver extraction process in mining, the generated residues (called tailings) still contain approximately 100-140 g/ton of silver due to the presence of refractory materials that trap this metal and prevent its solubilization by conventional methods. These residues can be treated by biohydrometallurgical processes allowing, together with the cyanidation process, an increase in the efficiency of silver extraction by eliminating refractory materials such as manganese, which is present as pyrolusite (MnO2, 3.78 %). Pyrolusite can change from manganese (IV) to manganese (II) when solubilized by bioleaching. This research analyzed the effects of bioleaching using native bacteria on the concentration of silver extraction from the removal of manganese in mining tailings. The native bacteria ITDBC2, ITDBC5, and ITDBC6 were identified as Leptospirillum ferriphilum by amplification of the 16S gene corroborated by bioinformatic analysis. The experimentation was carried out using a flooded bioleaching system (9.43 L) to resemble the industrial geometry with the following variables: concentration of ferrous ions (2, 7, and 14 g/L), pH (2, 4, and 6) and agitation time at 100 rpm (2, 4 and 6 min/day). The experimentation lasted 18 days. The removal of manganese and silver extraction was 71.84 and 55.53 %, respectively. The scaled-up of the evaluated bioprocess could reduce energy consumption and process larger amounts of pulp than the reported at the laboratory scale.

Manganese bioleaching: an emerging approach for manganese recovery from spent batteries

Manganese bioleaching: an emerging approach for manganese recovery from spent batteries

Bioleaching Ability of Fungi Isolated from an Indonesian Sulfurous River Sediment

The unique characteristics of sulfurous river sediment located in Ungaran, Indonesia, are a reservoir of novel fungi with manganese bioleaching properties. Fungi are known to produce metabolic organic acids that have a potential for the industrial application of leaching metal from the ores. This application has high advantages, including low cost, low energy, and creates minimal environmental damage. Therefore, this research was performed to analyze the manganese bioleaching activities of two fungal isolates (KA2B2 and KB4B) from Indonesian sulfurous river sediment on pyrolusite and determine their phenotypic characters. These activities were investigated in terms of changes in fungal biomass, soluble manganese concentration, pH reduction, and organic acid production during 16 days of leaching. Soluble manganese concentrations were measured by atomic absorption spectrometry (AAS), whereas organic acid concentrations were analyzed by high-performance liquid chromatography (HPLC). According to bioleaching investigations, KA2B2 strain was more efficient than KB4B1 strain in extracting manganese from 0.02 g/cm3 pyrolusite. It also produced higher levels of organic acids, such as oxalic acid and citric acid, than KB4B1 strain, proving that strain of KA2B2 could be used to extract manganese from pyrolusite. Based on the phenotypic characters, both strains were identified as genus Penicillium.

Response Surface Methodology Analysis of the Effect of the Addition of Silicone Oil on the kLa Coefficient in the Bioleaching of Mine Tailings

Bioleaching is suggested as a methodology with benefits in ex situ/in situ bioremediation for reducing metal contamination in dredged sediments. The process of bioleaching assisted by microorganisms in a stirred tank is widely used, among other biohydrometallurgical techniques, for the efficient extraction of metals of interest if the recovery costs of valuable metals allow it. Measurement of the mass transfer capacity of oxygen in an aerobic bioreactor is of vital importance; this factor determines the productivity of the system, since it promotes microbial growth and hence enables a bioconversion process at the mineral surface takes place. The main objective of the present research was to determine the volumetric oxygen transfer coefficient (kLa) during the manganese bioleaching process in a stirred tank reactor using silicone oil as a vector to improve the transfer of gaseous substrates. Experiments were carried out in triplicate with a 22 factorial design analyzing temperature (30 and 40 °C) and stirring speed (300 and 500 rpm). The effect of viscosity on the system was also determined by modifying the concentrations of mining waste (30, 40, and 50%), ferrous sulfate (FeSO4 · 7H2O) (2, 4, 8, and 14%), and silicone oil (0, 5, and 10%) at 0 and 24 h of mixing. The results showed an increase in the value of kLawith respect to time, from kLa(0 h, 30 °C, 500 rpm) = 8.75 s−1 to kLa(24 h, 40 °C, 500 rpm) = 18.18 s−1; ANOVA statistical analysis was performed with the Fisher and Tukey tests and showed that there were statistically significant differences.

Environmentally-friendly bioleaching of manganese from pyrolusite: Performance and mechanisms

Currently, bioleaching of manganese (Mn) from Mn-poor ore (e.g. pyrolusite) is facing the challenges of low leaching efficiency and high cost of leachant and process operation. In this study, a new process was developed that uses Microbacterium trichothecenolyticum Y1 (bacteria Y1) and waste molasses to bioleach Mn from pyrolusite or pure MnO2 (for comparison). Results indicate that the innovative process can be operated at normal temperature/pressure and a weak acidic condition (pH = 3.5) with a much improved Mn bioleaching efficiency (about 98% in 6–8 days) as compared with the previously-reported efficiencies (only 60–80%). The optimal conditions were found as the solid-liquid ratio of 1 kg of mineral powder to 20 L of leaching liquid, pH 3.5, anaerobic, stirring speed of 80 rpm, temperature 45 °C and waster molasses dose of 2.5 g L−1. The associated mechanism was elucidated with the help of different equipment and methods. The leaching process first reduced Mn(IV) in MnO2 to Mn(II) as MnO in the solid phase and then dissolved Mn(II) into the liquid phase. Bacteria Y1 could produce a large number of tyrosine-like substances in the system, which promoted the decomposition of sugar and Mn(IV) reduction. Weak acid (pH = 3.5) could destroy biofilm and manganese oxides (e.g., MnO) on mineral surfaces to promote the leaching process. Kinetic studies show that the pyrolusite leaching process belongs to mixed control by solid film diffusion control and chemical reaction control. The innovative process may be cost-effective and green, with a great potential for future applications.

Optimization of manganese bioleaching activity and molecular characterization of indigenous heterotrophic bacteria isolated from the sulfuric area

Abstract. Prasidya DA, Wilopo W, Warmada IW, Retnaningrum E. 2019. Optimization of manganese bioleaching activity and molecular characterization of indigenous heterotrophic bacteria isolated from the sulfuric area. Biodiversitas 20: 1904-1909. The present research evaluated the manganese bioleaching potency of a heterotrophic bacteria KB3B1. This bacterial strain has been isolated from sulfuric area located at Ungaran, Middle of Java, Indonesia using modified 9K medium by adding of several organic nutrients. The manganese bioleaching activities of the strain was analysed by applying of varying glycine concentrations (0, 5, 10, 15 mg mL-1) with pyrolusite pulp densities of 0.02 g cm-3 on a rotary shaker at 180 rpm for 18 days incubation. Several parameters, including the growth of bacteria, pH values, the concentration of soluble manganese and cyanide, were investigated at the interval of 3 days. Molecular characteristics of the strain were further analyzed based on 16S rDNA gene sequences. After 15 days, the maximum yield of manganese 16.6% was achieved under the addition of 10 mg mL-1 glycine. This maximum extract obtained was followed by the maximum bacterial growth, pH, and cyanide product of the strain. Phylogenetic analysis showed that the strain was closely related with Bacillus niacini EP89. Besides, the average frequencies of guanine and cytosine (G+C) of the strain was in same range as that of the reference bacteria in the GenBank and Bergey's Manual Systematics of Bacteria.

Pyrolusite Bioleaching by an Indigenous <i>Acidithiobacillus</i> sp KL3 Isolated from an Indonesian Sulfurous River Sediment

The manganese bioleaching process of pyrolusite from Kliripan, Indonesia using Acidithiobacillus sp KL3 was investigated. The influence pulp densities of pyrolusite (0.01, 0.02, 0.03 and 0.05 g/cm3) on the bioleaching processes were studied for 16 days. The reduction on pH values, the increasing of oxidation-reduction potential (ORP), sulfate and manganese concentration were analyzed. The manganese bioleaching mechanism of pyrolusite by the strain was monitored using Scanning Electron Microscope-Energy Dispersive-X-ray Spectroscopy (SEM-EDX). The results indicated that 0.02 g/cm3 of pyrolusite was considered to be the optimal pulp density for manganese bioleaching process. During this process, pH values decreased, furthermore resulted in increasing of ORP, the concentration of sulfate and manganese. SEM-EDX analysis clearly showed the evidence of directly bacterial cell attachment into the surface of pyrolusite. Extracellular polymeric substances (EPSs) were further founded on that surface. Sulfur elemental was oxidized by the strain which was then confirmed of resulting in solubilized manganese.

Effects of Acidithiobacillus ferrooxidans and Fe(III) on pyrite–pyrolusite bioleaching process

The beneficial effects of Acidithiobacillus ferrooxidans and/or Fe(III) on manganese bioleaching from a low-grade manganese ore were confirmed. The results showed that the rate of manganese bioleaching increases with the amount of A. ferrooxidans and/or Fe(III). With the presence of Fe(III) and A. ferrooxidans the average initial leaching rate increased from 0.06 to 0.15 g/(L h). Cyclic voltammetry analysis showed that the presence of A. ferrooxidans and/or Fe(III) generate obvious redox potential polarization in the solution. Fe(III) reduced the potential difference between anode and cathode of pyrite and promoted the positive cathodic polarization of pyrolusite at 0.2 V. In the process of pyrite oxidation A. ferrooxidans accelerated the generation and transfer of electron.

Bioleaching of manganese by Aspergillus sp. isolated from mining deposits

A comprehensive study on fungus assisted bioleaching of manganese (Mn) was carried out to demonstrate Mn solubilization of collected low grade ore from mining deposits of Sanindipur, Odisha, India. A native fungal strain MSF 5 was isolated and identified as Aspergillus sp. by Inter Transcribed Spacer (ITS) sequencing. The identified strain revealed an elevated tolerance ability to Mn under varying optimizing conditions like initial pH (2, 3, 4, 5, 6, 7), carbon sources (dextrose, sucrose, fructose and glucose) and pulp density (2%, 3%, 4%, 5% and 6%). Bioleaching studies carried out under optimized conditions of 2% pulp density of Mn ore at pH 6, temperature 37 °C and carbon dosage (dextrose) resulted with 79% Mn recovery from the ore sample within 20 days. SEM-EDX characterization of the ore sample and leach residue was carried out and the micrographs demonstrated porous and coagulated precipitates scattered across the matrix. The corresponding approach of FTIR analysis regulating the Mn oxide formation shows a distinctive peak of mycelium cells with and without treated Mn, resulting with generalized vibrations like MnOx stretching and CH2 stretch. Thus, our investigation endeavors’ the considerate possible mechanism involved in fungal surface cells onto Mn ore illustrating an alteration in cellular Mn interaction.

Manganese-electrolysed slag treatment: bioleaching of manganese by Fusarium sp.

A fungi strain named Fusarium sp. was isolated from manganese-electrolysed slag by using a gradient dilution spread plate method, identified by 26S RNA sequence analysis and phylogenetic tree analysis, and explored for the bioleaching capacity to manganese (II) from manganese-electrolysed slag in liquid mineral medium under different environmental conditions, including system temperature, incubator rotation speed and initial pH value. DNA sequence and phylogenetic analysis indicated the name of this fungi strain, that is, Fusarium sp., and higher bioleaching efficiencies (71.6%) of manganese by this fungi were observed when the bioleaching was carried out under the optimized conditions as follows: contact time: 72 h; system temperature: 28°C; inoculums concentration: 2% (v/v); incubator rotation speed: 150 rpm; pH 4.0. Because of its low cost, environment friendliness and better efficiency, the bioleaching technique will have a significant impact on manganese-electrolysed slag pollution mitigation.

Biokinetics of Thiobacillus thiooxidans for manganese bioleaching

The waste tailing of metals generated during mining processes is degrading the environment by increasing the soil toxicity, leading to disturbances in the ecosystem. This study was initiated to determine the biokinetics of Thiobacillus thiooxidans for manganese bioleaching in the presence of excess sulphur. In batch studies, the effect of manganese concentration on the leaching efficiency of T. thiooxidans was also evaluated, and it was found that as the concentration of manganese increases, the leaching efficiency decreases. This may be due to an inhibitory effect of manganese at higher concentrations. The maximum leaching efficiency of more than 95% was found at lower manganese concentration of 5-25 mg/litre, while the efficiency significantly decreases to 35% at 200 mg/litre manganese. The biokinetic coefficient (maximum growth rate and inhibition constant) was also determined for T. thiooxidans for manganese bioleaching using Haldane's equation. A linear mathematical relationship was also developed between leaching efficiency, initial manganese concentration and time of incubation, which would be useful in predicting the leaching efficiency under various conditions. The significance test using T-paired test was also performed, and it was found that the theoretical leaching efficiency is above 95% confidence level from observed leaching efficiency. The above parameters are invariably required for the design and simulation of batch and continuous bioreactors for bioleaching of manganese tailings. The present work may be useful for management of tailing waste generated during mining processes.

Bioleaching of silicate manganese ores

Organic acids excreted by microorganisms dissolve manganese from silicate ores. Oxalic acid is more effective than citric, gluconic, and glycolic acid. Eighteen percent of the manganese in manganese silicate ore from Razoare, Romania, was dissolved within 6 days. Improvement of leaching conditions increased this to 20% within 6 h. Besides the manganese in the ore, 45% of the aluminum and 8% of the iron were dissolved in this time interval. This demonstrates that bioleaching of manganese from silicate ore is feasible, thus opening up new possibilities for the mineral processing industry.

Bioleaching of manganese (IV) oxide and application to its recovery from ores

Bioleaching of manganese (IV) oxide with Thiobacillus thiooxidans has been studied in media with and without sulfur, ferrous sulfide and ferrous sulfate. The knowledge of the role played by the bacteria and the reducing substances suggest that the leaching of manganese (IV) ores through the use of thiobacteria is only justified when suitable amounts of sulfur or metal sulfides are present.

Selective and non-selective bioleaching of manganese from a manganese-containing silver ore

Batch culture experiments showed that manganese could be leached from a manganese-containing silver ore by bacterial strain SSW 22, by a mixed culture derived from unsterilized ore, and by a Penicillium strain isolated from the mixed culture. The extent of leaching was influenced by the kinds of electrolytes and their concentration in the culture medium. The Penicillium strain was the most active. It leached manganese by a nonenzymatic mechanism. Leaching studies with Penicillium in a stirred reactor showed that at low chloride concentration (equivalent to 0.06% NaCl) manganese was leached selectively from the ore, whereas at high chloride concentration (equivalent to 3% NaCl or synthetic seawater) both manganese and silver were readily leached from the ore. Reactor leaching of ore showed the greatest promise for possible commercial exploitation.