Bioleaching Solution Research Articles

Bioleaching Solutions Used for the Nanoparticles Biosynthesis for Uranium and Arsenic Immobilization

Bioleaching solutions from uranium and arsenic solid waste served as a source of U(VI) and As (V) ions, while plant extract from green tea (Camellia sinensis) – as a reductor for nanoparticle synthesis. Uranium dioxide and As (III) nanoparticles were formed as a product of bioreduction on the hematite and schwertmannite surfaces respectively, which resulted in an increase in the negative zeta potential with an increase in pH. It suggests, that the electrical potential depends on the presence of nanoparticles. The SEM microphotographs revealed the UO2 nanoparticles on the hematite surface.

Advances in bioleaching of copper and nickel from electronic waste using Acidithiobacillus ferrooxidans: evaluating daily pH adjustment

The waste stream of electrical and electronic equipment is three times faster than other municipal waste streams. Recycling of electronic waste is necessary for both reducing environmental pollution and saving natural ores. Bioleaching is known as an efficient technology for metal leaching. In most of the previous studies on the bioleaching of electronic waste, the pH of the process was adjusted daily under the optimal pH of the bacterium growth. Using acid causes increasing process costs and unsustainability of the process. In this work, the effect of daily pH adjustment on the bioleaching efficiency of electronic waste using adapted Acidithiobacillus ferrooxidans was studied. Simultaneously, Cu and Ni leaching efficiency, bacterial growth characteristics, and chemical characteristics (including field emission scanning electron microscopy, Fourier transform infrared spectrometer, and X-ray diffraction) were discussed. The results showed that at a pulp density of 1.5% (w/v) with pH adjustment, the maximum leaching efficiency of Cu and Ni was, respectively, about 90% and 88%, while for the sample without pH adjustment, the maximum leaching efficiency of Cu and Ni was, respectively, 100% and 92%. All the results confirmed pH adjustment of the bioleaching solution is not necessary and even reduces the process efficiency.

Adsorption Behaviors of Rhodotorula sp. in the Bioleaching Process of Acidithiobacillus ferrooxidans

AbstractExcessive heavy metal ions in a bioleaching solution can negatively affect Acidithiobacillus ferrooxidans and consequently reduce the leaching rate. This work aims to verify the adsorption ...

Optimization and kinetics of copper cementation from bio-leachate generated during the waste printed circuit board (E-waste) processing

The leach solutions of waste printed circuit boards contain a variety of base as well as precious metals with different concentrations. So, it is necessary to recover such metals for downstream processing of leach solutions. Cementation process is widely used at the industrial scale due to lower operational cost. In the present study, recovery of copper was performed by scrap iron and aluminium as cementing agents. Use of scrap iron resulted in a 99% copper recovery. Effects of different process parameters were studied to achieve maximum copper recovery. Kinetic study of copper cementation showed that the rate-controlling step was diffusion and the activation energy was 38.83 kJ/mol. Using flask data, the scale-up study was carried out with scrap iron for 8 L of the pregnant bio-leach solution. Complete recovery of copper was achieved within 120 min of reaction time in the scale-up study. The purity of recovered copper was 93% after the recovery process. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM- EDX) and X-ray powder diffraction (XRD) analysis of recovered copper was performed to characterize the recovered metal.

Optimal electronic waste combination for maximal recovery of Cu-Ni-Fe by Acidithiobacillus ferrooxidans

Abstract E-waste has become one of the greatest sources of environmental pollution. Bioleaching is known as a new, simple, and environmentally friendly technology for metal recovery requiring low energy input, unskilled labor operations, moderate conditions, and low costs. Acidithiobacillus ferrooxidans is a famous and puissant mesophilic bacterium applied extensively to recover metals from ores and different industrial and municipal wastes. It is necessary to identify the parameters affecting consumers E-waste recycling. Separating and recovering different types of E-waste is impossible for small recycling units. There should be a specific combination of E-waste, enabling the extraction of the maximum amount of precious metals. The main objective of the present study is finding the optimal combination of the most important printed circuit boards (PCBs) to maximize recovery of Cu, Ni, and Fe (as the most gold inhibitor metals) using adapted A. ferooxidans. The polymers and low-density materials were separated using the shaking table method to reach a concentrated sample. A. ferooxidans was adapted to the 15 g/l of the defined samples within 177 d. The D-optimal method was adopted to find the optimum E-waste combination. Pulp density, inoculum size, temperature, and stirring rate were fixed at 15 g/l, 10% (w/w), 30 °C , and 130 rpm in all experiments. The optimal percentages of computer PCBs plus CPUs, mobile phone PCBs, TV PCBs, copy machine PCBs, and fax PCBs were determined as 21.5%, 43.5%, 3%, 13.5%, and 18.5%. The application of this optimal E-waste composition resulted in 100% Cu and Fe extraction and 54% Ni recovery. It was concluded that increasing the concentration of a definite metal in PCB mixtures improves the recovery efficiency of that metal. Increasing Cu concentration in the bioleaching solution decreases Fe recovery. Significant amount of Cu and Fe in all samples reduces Ni recovery.

Membrane treatment of leached mining waste – A potential process chain for the separation of the strategic elements germanium and rhenium

Microfiltration, nanofiltration, and reverse osmosis allow for separating multicomponent solutions. These membrane techniques are applied for the separation and concentration of several components on a scale of a micron down to an atomic range from aqueous solutions. This work showcases a potential process chain for the recovery of germanium and rhenium from an acidic bioleaching solution containing sludge particles. The focused feedstock is an anthropogenic mining waste (Theisen sludge) containing various valuable metals which were mobilized by bioleaching. For particle removal a rotating microfiltration (0.2 and 2.0 µm) system was utilized, showing that >99% of the leached sludge particles are retained. By nanofiltration >99% of the cationic transition metals were removed and the target elements germanium and rhenium are separated in reverse osmosis, which follows suit. Thereby, germanium remains in the retentate and rhenium is separated in the permeate. The filtered streams are intended for further downstream processes such as solvent extraction and adsorption.

Recovery of copper from a mixture of printed circuit boards (PCBs) and sulphidic tailings using bioleaching and solvent extraction processes

The extraction of copper from a mixture of a Cu-Ni-Co bearing sulphidic tailing and printed circuit boards was investigated by bioleaching process followed by solvent extraction of the pregnant leach solutions. Bioleaching was conducted in both batch and continuous modes in 2- and 50-L stirred tank bioreactors using a mixed culture of iron- and sulphur-oxidizing microorganisms. The results of bioleaching in three 50-L reactors showed that 92% copper, 67% zinc and 45% aluminum were extracted in a batch mode. The process was then performed in the continuous mode in which 96.8% of copper was leached with 10 days’ residence time. Afterward, the bioleach solutions containing 2.85 g/l Cu was purified by solvent extraction with LIX 984 N extractant diluted in kerosene. The effect of some critical parameters namely extraction time, pH, stirring rate, aqueous/organic phase ratio and extractant concentration on the extraction efficiency of copper was investigated. Results showed that copper can be efficiently extracted from the bioleach solution in two stages (96% extraction). The co-extraction of zinc and nickel was increased at the higher level of pH (2.5). A new flowsheet was proposed to treat both electronic wastes and sulphidic tailings.

Effect of iron transformation on Acidithiobacillus ferrooxidans bio-leaching of clay vanadium residue

The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated. Acidithiobacillus ferrooxidans affects the dissolution of vanadium through the catalytic effect on Fe3+/Fe2+ couple and material exchange. The passivation of iron settling correlates with ferrous ion content in bio-leaching solution. In medium containing A. ferrooxidans and Fe(III), the increment in Fe(II) concentration leads to the formation of jarosite, generating a decline in vanadium extraction efficiency. Analysis of cyclic voltammetry shows that Fe(II) ion is apt to be oxidized and translated into precipitate by A. ferrooxidans, which strongly adsorbed to the surface of the residue. Fe(III) ion promotes the vanadium extraction due to its oxidizing activity. Admixing A. ferrooxidans to Fe(III) medium elevates the reduction of low valence state vanadium and facilitates the exchange of substance between minerals and solution. This motivates 3.8% and 21.8% increments in recovery ratio and leaching rate of vanadium compared to the Fe(III) exclusive use, respectively. Moreover, Fe(II) ion impacts vanadium extraction slightly in sterile medium but negatively influences vanadium leaching in the presence of bacteria.

Electrochemical Behavior of Ocean Polymetallic Nodules and Low-Grade Nickel Sulfide Ore in Acidithiobacillus Ferrooxidans-Coupled Bio-Leaching

Efficient extraction of Ni, Co, Cu, and Mn from low-grade and refractory ores is a common technical challenge. The present study proposes an Acidithiobacillus ferrooxidans-coupled leaching of Ni, Cu, Co, and Mn from oceanic polymetallic nodules and low-grade nickel sulfide ore, and focuses on the electrochemical behavior of the ores in simulated bio-leaching solutions. In the dissolution of polymetallic nodules, A. ferrooxidans facilitates the diffusion of H+ and accelerates electron transfer, producing a decrease in charge transfer resistance and promoting the Mn(IV)-preceding reaction. The use of A. ferrooxidans is beneficial for lower impedance of sulfur-nickel ore, faster diffusion rate of product layer, and better transformation of the Fe3+/Fe2+ couple and S0/S2− couple. A. ferrooxidans increases the potential difference between the nodule cathode and sulfide anode, and increases electron liberation from the sulfide ore. This motivates a significant increase in the average extraction rates of Ni, Co, Cu, and Mn in the bacterial solution. The bio-leaching efficiencies of Ni, Co, Cu, and Mn were as high as 95.4%, 97.8%, 92.2% and 97.3%, respectively, representing improvements of 17.1%, 11.5%, 14.3% and 12.9% relative to that of the germ- and Fe(III)-free acidic 9 K basic system.

Effluents Treatment Generated by Biolixiviation in the Extraction of Precious Metals through Selective Recovery of Iron, Copper and Zinc

Bioleaching comprises the use of microorganisms for metal-extraction processes from sulphide ores. During these complex processes, sulphides are oxidized to sulphates with the generation of heat. As a result, gold, silver, and other precious metals are liberated from the sulphide matrix, improving their recovery after further processing. A drawback of bioleaching processes is the generation of significant amounts of acid solutions with high heavy metal concentrations. If untreated, these acid solutions may alter the physical and chemical characteristics of water and its surroundings, with high impact to aquatic ecosystems. High heavy metal concentrations in solution may also result in pollution to living organisms. A feasible method to treat bioleaching-generated solutions is selective precipitation. This investigation presents the conditions for a successful individual recovery of the main base metals contained in a bioleaching solution with high copper, zinc, and iron concentrations by pH-based selective precipitation. Tests were made with standard solutions of known concentrations of copper, iron, lead and zinc and by titration the concentrations were checked; which allowed to validate the volumetric titration method. The selective precipitation of heavy metals was carried out in three phases using real acid main drainage and bioleaching solutions generated at the laboratory. The first phase in a pH range of 2 to 4 to recover iron; the second phase in a pH range of 4 to 6 to recover copper; and the third phase in a pH range of 6 to 10 to recover zinc. The selective precipitation allowed the heavy metals to be completely removed from the solution or to achieve concentrations below the maximum allowable limit to be discharged to a body of water or public sewer. Results portray that the variation of pH is an effective method, easy to use and not expensive, feasible to be used in the purification of waters that have been polluted with heavy metals.

Removal Performance of Silica and Solid Colloidal Particles from Chalcopyrite Bioleaching Solution: Effect of Coagulant (Magnafloc Set #1597) for Predicting an Effective Solvent Extraction

Removal Performance of Silica and Solid Colloidal Particles from Chalcopyrite Bioleaching Solution: Effect of Coagulant (Magnafloc Set #1597) for Predicting an Effective Solvent Extraction

Additional recovery of gold from waste after processing of gold-containing ores of Kazakhstan

The one of the important activities of gold mining industry is the involvement of refractory hard-to-enrich gold-containing raw materials into retreatment, as well as the tailings dams, which occupy huge areas and worsen the ecological state of the regions.The studies are aimed at re-extraction of gold out of technogenic raw materials possess not only scientific and practical, but also social and environmental significance. The pre-oxidation procedures are applied in the retreatment of raw materials, one of which is bio-oxidation of gold-containing raw materials method using A.Ferrooxidans bio-leaching solution.This method makes it possible to intensify the process of bio-oxidation extraction of gold from gold-containing raw materials due to the deeper development of sulphides. Therefore, the studies aimed at increasing the efficiency of gold re-extraction out of technogenic raw materials are of current interest. The results of researches regarding the extraction of gold out of stale tailings of gold extraction plant Altyntau Kokshetau using A.Ferrooxidans bio-leaching solution are performed in the article. The chemical, mineral and X-ray phase matter of sample was studied. It has been shown that the sample has a silicate base, represented by quartz, albite-anorthite mixture, muscovite and kaolinite.It has been found that the sample contains 8.49 g / t Au and 2.4 g / t Ag. The different leaching options were carried out: 1) re-grinding is followed by cyanidation; 2) cyanide leaching with preliminary sulfuric acid washing; 3) bio-oxidation using A.Ferrooxidans bacterial solution. It has been shown that the use of preliminary bio-oxidation makes it possible to increase the gold extraction. As a result, it was found that re-extraction of gold out of the stale tailings of sorption by two-stage leaching – bacterial opening of the raw materials, and then cyanidation are the most effective one.The best indicator of gold extraction in solutions as regards the first option resulted in 62.7% of gold, at the second option with the use of sodium chloride and the subsequent cyanidation was 79%, and at the third option of biochemical technology with sodium cyanide was 82.8% of gold.

Missing research focus in end-of-life management of light-emitting diode (LED) lamps

The spent light emitting diode (LED) monitors are one of the fastest-growing waste streams that could provide indium, an essential element for the industry. This study presents a comprehensive strategy for indium extraction from spent LED monitors, including bioleaching followed by solvent extraction, stripping, and precipitation. Effects of A. thiooxidans and A. ferrooxidans inoculum percentage in mixed culture, pulp density, and time on indium, aluminum, and strontium bioleaching were investigated. In this regard, at optimized inoculum percentages (1.5 and 0.5% (v/v) of A. ferrooxidans and A. thiooxidans, respectively) and pulp density (60 g/L) at initial pH of 2, approximately 100% indium recovery was obtained in 18 days. The solubilized indium in the bioleaching solution has been extracted by the organic solvent of 20% (v/v) D2EHPA in kerosene. Following extraction, the stripping step was carried out to recover indium rather than iron selectively. The effect of two-phase contact time and aqueous to organic phase volume ratio in the extraction step and the acid type and concentration in the stripping step on indium and iron recovery percentages have been evaluated. For indium extraction, the optimum ratio of aqueous to organic phase volume and time were determined as 1 and 30 min, respectively, recovering 91.5% of indium. Using 5 M sulfuric acid has also resulted in an efficient stripping process. Finally, sodium hydroxide performed indium precipitation and a final precipitate of 94% (w/w) indium was obtained.

Method for the Recovery of Indium from Diluted Bioleaching Solutions

Using a commercially available solvent impregnated resin, Lewatit TP272, in an ion exchange process, it was possible to extract up to 90 % indium from a feed containing as little as 1 mg/L indium in the presence of high amounts of impurities, i.e. 1000 mg/L iron and zinc each. It was demonstrated that through gradient regeneration of obtained loaded ion-exchange resin, it is possible to yield a solution containing as much as 400 mg/L indium along with 400 mg/L iron, thereby upgrading its purity more than 600 times. Moreover, it was shown that this solution can be fed into an existing solvent extraction procedure which would yield an indium oxide with more than 99 % purity.

Lithium recovery from lithium-containing micas using sulfur oxidizing microorganisms

There is about 60,000 t of lithium mica in the German part of the deposit in the Erzgebirge mountains. Lithium can be recovered by high pressure-high temperature leaching with sulfuric acid and further hydrometallurgical processing. Another idea, developed in the EU-project FAME, was to use sulfur oxidizing microbes to produce sulfuric acid and to extract lithium at moderate temperature and pressure conditions. Experiments were carried out in 2L and 4L batch reactors at 30°C. After microbial transformation of elemental sulfur to sulfuric acid, the milled (<45µm) lithium mica was added at a pulp density of 5%. Up to 26% of lithium was extracted biologically compared to 16% by chemical leaching. The bioleaching solution contained about 1g/L aluminium, 0.8g/L iron and 0.2g/L lithium and could be further processed hydrometallurgically.

Tellurium speciation in a bioleaching solution by hydride generation atomic fluorescence spectrometry

The speciation analysis of tellurium in a bioleaching solution is of great importance for the study of the bacteria leaching mechanism of tellurium ores and further separation and extraction of tellurium from the solution.

Oxygen solubility in copper bioleaching solutions

Oxygen is usually the limiting reagent in bio-leaching processes. For this reason, aeration is a key point to take into account when designing such processes, and the oxygen saturation concentration is an important variable to know. Currently, there is a lack of data or models to accurately predict the concentration at which oxygen saturates under the operational conditions during copper bio-leaching.For this paper, oxygen solubility was measured in solutions containing the main electrolytes present in bio-leaching solutions: sulphuric acid, ferrous sulphate, ferric sulphate, and copper sulphate; measurements were performed throughout the range of concentration that is characteristic to each electrolyte. These solutions were obtained by microbiological oxidation of ferrous sulphate, and were exposed to air, at atmospheric pressure, until oxygen saturation occurred. Measurements were taken using a dissolved-oxygen electrode. From the results, the equation is obtained:Si=S°−12.698⋅10−pH−0.0555⋅Fe2+−0.0290⋅Fe3+−0.0265⋅Cu2+that predicts oxygen solubility in copper bio-leaching liquors from the simple measurement of pH and Fe2+, Fe3+, and Cu2+ concentrations.

Separation of Cu from dilute Cu–Ni–Co bearing bioleach solutions using solvent extraction with Chemorex CP-150

ABSTRACTSolvent extraction of Cu from simulated and real bioleaching solutions obtained from a complex Cu–Ni–Co bearing tailing was investigated using Chemorex CP-150 extractant. The effects of several critical parameters, namely pH, contact time, extractant concentration, metal ion concentration, and organic/aqueous phase ratio on Cu extraction were evaluated. Isotherm studies showed that more than 99.9% Cu was transferred with a single stage for each of the extraction and stripping steps. A mixed Ni–Co sulfide was produced from the extraction effluent. A developed flow sheet was proposed to treat Cu–Ni–Co bearing sulfidic tailings by bioleaching, jarosite precipitation, solvent extraction, and sulfide precipitation processes.

Synthesis of argentojarosite with simulated bioleaching solutions produced by Acidithiobacillus ferrooxidans

Argentojarosite (AgFe3(SO4)2(OH)6) is formed as a secondary phase in Ag-catalyzed bioleaching of chalcopyrite (CuFeS2), but to date very little is known about the paragenesis or characteristics of this silver-containing compound. The purpose of this study was to synthesize argentojarosite via biological oxidation of 120mM ferrous sulfate by Acidithiobacillus ferrooxidans. Because of its toxicity to A. ferrooxidans, Ag+ (as AgNO3) was added to spent culture media (pH2) after complete oxidation of ferrous sulfate. Schwertmannite (ideally Fe8O8(OH)6(SO4)) was precipitated during the iron oxidation phase, and subsequent Ag+ addition resulted in the formation of argentojarosite. Contact time (8h, 5d, and 14d) and Ag+ concentration (0, 5, 20, and 40mM) were used as variables in these experiments. Synthesis of argentojarosite, schwertmannite and other mineral phases was confirmed through X-ray diffraction analysis. Additional analyses of solid-phase oxidation products included elemental composition, color and specific surface area. The sample synthesized in the presence of 40mM Ag+ and with 14d contact time yielded an X-ray diffraction pattern of well crystallized argentojarosite, and its elemental composition closely matched the calculated Ag, Fe, and S contents of ideal argentojarosite. The color and surface area of the remaining samples were influenced by the presence of residual schwertmannite. This phase remained stable over the time course of 14d when no Ag+ was present in the system. When equilibrations were extended to 42d, partial conversion of reference schwertmannite to goethite was noted in the absence of Ag. In the presence of 20mM or 40mM Ag over the same time course, some formation of argentojarosite was also noted. In this case, schwertmannite was the only source of Fe and SO4 for argentojarosite formation.

Effects of pyrite bioleaching solution of Acidithiobacillus ferrooxidans on viability, differentiation and mineralization potentials of rat osteoblasts.

Iron pyrite, an important component of traditional Chinese medicine, has a poor solubility, bioavailability, and patient compliance due to a high dose required and associated side effects, all of which have limited its clinical applications and experimental studies on its action mechanisms in improving fracture healing. This study investigated Acidithiobacillus ferrooxidans (A.f)-bioleaching of two kinds of pyrites and examined bioactivities of the derived solutions in viability and osteogenic differentiation in rat calvarial osteoblasts. A.f bioleaching improved element contents (Fe, Mn, Zn, Cu, and Se) in the derived solutions and the solutions concentration-dependently affected osteoblast viability and differentiation. While the solutions had no effects at low concentrations and inhibited the osteoblast alkaline phosphatase (ALP) activity at high concentrations, they improved ALP activity at their optimal concentrations. The improved osteoblast differentiation and osteogenic function at optimal concentrations were also revealed by levels of ALP cytochemical staining, calcium deposition, numbers and areas of mineralized nodules formed, mRNA and protein expression levels of osteogenesis-related genes (osteocalcin, Bmp-2, Runx-2, and IGF-1), and Runx-2 nuclear translocation. Data from this study will be useful in offering new strategies for improving pyrite bioavailability and providing a mechanistic explanation for the beneficial effects of pyrite in improving bone healing.