Biometallurgical Processes Research Articles

Bio-metallurgical recovery of lithium, cobalt, and nickel from spent NMC lithium ion batteries: A comparative analysis of organic acid systems

With the increasing demand for lithium-ion batteries, key elements like lithium, graphite, cobalt, and nickel face heightened demand and classification as critical by the European Commission. This study investigates a bio-metallurgical approach for recovering these elements from NMC/C electrode material. The method leverages Aspergillus niger's acid production capacity. Lab experiments involved leaching pyrolyzed black mass using diverse multi-acid systems, including citric, DL-malic, gluconic, and oxalic acid. Parameters such as temperature, leaching time, solid-to-liquid ratio, and molasses as a reductant were varied. Nickel and cobalt recovery rates were modest, with highest rates (13% for Ni, 25.8% for Co) in DL-malic and gluconic acid-rich setups. Maximum lithium recovery (87.9%) occurred in a citric-rich medium. Analysis revealed organo-metallic components in solid residues and formed precipitates, implying oxalic acid's role in inhibiting recovery. Therefore, optimization of acid generation is crucial for effective bio-metallurgical recovery. In summary, this study highlights the potential of Aspergillus niger-mediated bio-metallurgical processes with organic acid mixtures for sustainable recovery of critical elements from spent lithium-ion batteries. The findings contribute crucial insights into optimizing leaching parameters and underscore the significance of bioleaching in addressing the demand for key battery materials. This work has important implications for advancing eco-friendly e-waste recycling practices and aligns with the principles of resource conservation and circular economy in the energy storage sector.

Harnessing the Capabilities of Microorganisms for the Valorisation of Coal Fly Ash Waste through Biometallurgy

Coal fly ash (CFA) is a highly versatile raw material that has the potential to yield multiple value-added products, including cenospheres, zeolites, carbon nanotubes, and fertiliser substrates. Despite its versatility, a majority of these components are often overlooked, and CFA is primarily used for construction. Conventional processing methods of CFA are known to pose significant environmental challenges, including the leaching of hazardous materials, emission of toxic gases, and the high energy consumption needed to extract the value-added components. Herein, we explore the potential of biometallurgical approaches as an eco-friendly alternative to conventional processing methods for the comprehensive utilisation of CFA. Our focus is on the application of different microorganisms to CFA, the domestication of microorganisms, preprocessing of CFA to facilitate effective biometallurgical processes, the use of bioreactors, and synthesis of nano silica particles. We also propose a novel method for extracting the value-added components from CFA using a preprocessing technique (i.e., washing cycle), combined with multiple interactions with biometallurgical processes. Adopting this approach, we not only enhance environmental stewardship but also improve the circular economic aspects of multi-component utilisation, while providing valuable insights for the development of sustainable techniques for utilising CFA.

Hybrid leaching of tantalum and other valuable metals from tantalum capacitor waste

We propose a novel integrated model for the recovery of tantalum from tantalum-rich waste using a combination of hydrometallurgical and bio-metallurgical processes. To this end, leaching experiments with heterotrophs (Pseudomonas putida, Bacillus subtilis and Penicillium simplicissimum) were carried out. The heterotrophic fungal strain leached manganese with an efficiency of 98%; however, no tantalum was detected in the leachate. An unidentified species did mobilise 16% tantalum in 28days in an experiment with non-sterile tantalum capacitor scrap. Attempts to cultivate isolate and identify these species failed. The results of a range of leaching trials resulted in an effective strategy for Ta recovery. A bulk sample of homogenised Ta capacitor scrap was first subjected to microbial leaching using Penicillium simplicissimum, which solubilised manganese and base metals. The residue was subjected to the second leach using 4M HNO3. This effectively solubilised silver and other impurities. The residue collected after the second leach was pure tantalum in concentrated form. The hybrid model produced derives from observations from previous independent studies and shows that we can effectively recover tantalum along with silver and manganese in an efficient and environmentally friendly manner from tantalum capacitor scrap.

Recovering valuable metals from Waste Printed Circuit Boards (WPCB): A short review

In the modern era, metal usage can be traced in almost anything from simple household tools to complex electronic equipment. About 95 % of the electronic equipment surrounding us is built using components containing valuable metals, such as gold, silver, copper, palladium, and rare earths. Recycling electronic equipment offers a much richer resource than extracting metals from their respective ores. Printed circuit boards (PCBs) form about 3–6 % of the total electronic waste yet contain considerable quantities of precious metals. Most of the electronic waste (e-waste) that is disposed of, such as computers, mobile phones, televisions, printers, etc., are equipped with PCBs. These products are equipped with printed circuit boards(PCB) which are rich in valuable metals, including copper, aluminium, and gold. Recycling e-waste, especially PCBs, provides a route for economical and profitable extraction of valuable metals other than mining. Waste PCBs can be recycled using mechanical, pyrometallurgical, hydrometallurgical, electrometallurgical, and biometallurgical processes. In this review, the different technologies available for PCB recycling are compared, their limitations are highlighted to appreciate an environmentally friendly recovery of metals from the WPCBs. The PCBs feature a complex composition; therefore, it requires an intricate and novel approach to extract the specific metals. The review briefly analyses the different methods and techniques to extract the constituent elements and serves as a reliable reference for recycling WPCBs.

Metallurgical Processing Strategies for Metals Recovery from Industrial Slags

Abstract Slag produced as a byproduct in industrial processes, contains considerable metals contents, which need to be recovered to avoid environmental contamination. In present review, the types, applications, recovery of metals from slag and their hazardous effects have been discussed. Gravimetric, magnetic, floatation, pyrometallurgical and hydrometallurgical treatments are discussed for processing of charge chrome, steel, copper smelter, brass smelter, tin, incineration, ferrochrome and silico-manganese slags for the extraction of various metal ions (Mg, Cu, Zn, Pb, Cd, Ni, Co, Mn, Fe, As, Cr, Al, Nb, Ag, Au, Nb, Ta, Cu, Co, Ni, Fe, V, Cr). The possibility of biometallurgical processing of slags is also evaluated. Merits and demerits of extraction and purification techniques are highlighted with possible suggestions and possibility of integrated leaching techniques is also discussed.

Sustainability of metal recovery from E-waste

The issue of E-waste disposal is concerning all the stakeholders, from policymakers to the end users which have accelerated the research and development on environmentally sound disposal of E-waste. The recovery of metals (gold, tantalum, copper, iron etc.) from E-waste has become an important focus. The mechanical recycling, thermo-chemical processes like pyrolysis, pyro-, hydro- and biometallurgical processes can play important roles in the Metal Recovery from E-waste (MREW) technology. For the industrial application of the MREW technology, it is important to analyze the sustainability. In this paper, two case studies have been presented on E-waste recycling industries in India and China. Based on the literature data, an attempt has been made to assess qualitatively the overall sustainability of MREW technology considering the three pillars, i.e., environmental, economic and social. Two conceptual frameworks with (Option-2) and without (Option-1) pyrolysis for integrated MREW units have been developed and the generalized energy and environmental impact analysis has been made using the principles of LCA. The impacts of two options have been compared. Option 2 has been found to be more efficient and sustainable. It has been realized that climate change, fossil fuel depletion, water depletion, eutrophication, acidification, fresh and marine water ecotoxicity are possible impact categories. The recommendations based on the generalized assessment are in good agreement with the findings of previous researchers on individual steps of MREW unit. The findings of this paper are expected to be beneficial to researchers and stakeholders for research directions and decision making on MREW.

Recovery of rare and precious metals from urban mines—A review

Urban mining is essential for continued natural resource extraction. The recovery of rare and precious metals (RPMs) from urban mines has attracted increasing attention from both academic and industrial sectors, because of the broad application and high price of RPMs, and their low content in natural ores. This study summarizes the distribution characteristics of various RPMs in urban mines, and the advantages and shortcomings of various technologies for RPM recovery from urban mines, including both conventional (pyrometallurgical, hydrometallurgical, and biometallurgical processing), and emerging (electrochemical, supercritical fluid, mechanochemical, and ionic liquids processing) technologies. Mechanical/physical technologies are commonly employed to separate RPMs from nonmetallic components in a pre-treatment process. A pyrometallurgical process is often used for RPM recovery, although the expensive equipment required has limited its use in small and medium-sized enterprises. Hydrometallurgical processing is effective and easy to operate, with high selectivity of target metals and high recovery efficiency of RPMs, compared to pyrometallurgy. Biometallurgy, though, has shown the most promise for leaching RPMs from urban mines, because of its low cost and environmental friendliness. Newly developed technologies—electrochemical, supercritical fluid, ionic liquid, and mechanochemical—have offered new choices and achieved some success in laboratory experiments, especially as efficient and environmentally friendly methods of recycling RPMs. With continuing advances in science and technology, more technologies will no doubt be developed in this field, and be able to contribute to the sustainability of RPM mining.

Considerations about recovery of critical metals using bio-metallurgy

The increased requirement of critical metals due to green technologies needs, together with the geopolitical environment to ensure these metals, has entailed decisive measures to avoid current supply insecurities in each country. These metals are essential to the products and services made and used daily, and contribute to sustaining and growing the economy. Thus, sustainable approaches from technological, environmental, economic and social point of view are needed to recover these metals from different resources. By using resources more efficiently, innovating in the concept of circular economy, it can be assure re-using, re-manufacturing or recycling of valuable materials. In this paper are presented some considerations related to using the waste dumps as potential resources to obtain critical metals by bio-metallurgical processes.

Considerations about recovery of critical metals using bio-metallurgy

The increased requirement of critical metals due to green technologies needs, together with the geopolitical environment to ensure these metals, has entailed decisive measures to avoid current supply insecurities in each country. These metals are essential to the products and services made and used daily, and contribute to sustaining and growing the economy. Thus, sustainable approaches from technological, environmental, economic and social point of view are needed to recover these metals from different resources. By using resources more efficiently, innovating in the concept of circular economy, it can be assure re-using, re-manufacturing or recycling of valuable materials. In this paper are presented some considerations related to using the waste dumps as potential resources to obtain critical metals by bio-metallurgical processes.

A Comparative Study on the Effect of Flotation Reagents on Growth and Iron Oxidation Activities of Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans

Recently, extraction of metals from different resources using a simple, efficient, and low-cost technique-known as bioleaching-has been widely considered, and has turned out to be an important global technology. Leptospirillum ferrooxidans and Acidithiobacillus (Thiobacillus) ferrooxidans are ubiquitous bacteria in the biomining industry. To date, the effects of commercial flotation reagents on the biooxidation activities of these bacteria have not been thoroughly studied. This investigation, by using various systematic measurement methods, studied the effects of various collectors and frothers (collectors: potassium amylxanthate, potassium isobutyl-xanthate, sodium ethylxanthate, potassium isopropylxanthate, and dithiophosphate; and frothers: pine oil and methyl isobutyl carbinol) on L. ferrooxidans and A. ferrooxidans activities. In general, results indicate that in the presence of these collectors and frothers, L. ferrooxidans is less sensitive than T. ferrooxidans. In addition, the inhibition effect of collectors on both bacteria is recommended in the following order: for the collectors, potassium isobutyl-xanthate > dithiophosphate > sodium ethylxanthate > potassium isobutyl-xanthate > potassium amylxanthate; and for the frothers, methyl isobutyl carbinol > pine oil. These results can be used for the optimization of biometallurgical processes or in the early stage of a process design for selection of flotation reagents.

Recovery of Metals from Printed Circuit Boards (PCBs) Using a Combination of Hydrometallurgical and Biometallurgical Processes

Printed circuit boards (PCBs) are one of the most important components of electronic equipment and encompass a variety of metals, including the majority of the valuable metals, and also most of the toxic components in e-waste. The objective of the present work proposes an integrated (hybrid) method for the recovery of copper (Cu), nickel (Ni) and zinc (Zn) from waste PCBs using a combination of biometallurgical (biological) and hydrometallurgical (chemical) processes. The recovery was effected using the combination of Acidithiobacillus ferrooxidans and 2 M HNO3. The leaching of metals was experimented using inorganic acid, bacteria and the integration of both acid and bacteria. From the initial experiments, it was observed that the percentage of nickel, copper and zinc solubilised into leaching solution from the actual PCB basically decreased with the increase in the concentration of e-waste from 10g/L to 100g/L. The hybrid method was compared against the individual chemical and biological methods and proved to be a better method than the other two, being rapid, efficient, economical and eco-friendly.

Biometallurgical Recovery of Metals from Waste Electrical and Electronic Equipment: a Review

AbstractThe feasibility of biometallurgical processing for recovering heavy metals, precious metals, and rare earth elements from waste electrical and electronic equipment (WEEE) is critically reviewed. An overview of past achievements, present scenarios, and future prospects of these techniques is given. The potential of various lithotrophic and organotrophic microorganisms is particularly highlighted for extracting metals by producing inorganic and organic acids in the process. The metal‐binding ability of various biomaterials including algae, fungi, bacteria, and yeast as well as certain biopolymers and biowaste materials, is reviewed in view of recovering metals from WEEE.Due to the increasing importance of heavy and precious metals and rare earths elements in the transition to a green energy economy based on high‐tech applications, coupled with the shortage of economical and/or operational primary deposits, a substantial improvement in the recycling of WEEE for recovery of metals is therefore an absolute necessity. This can only be realized by developing efficient and fully integrated recycling routes. Current work also focused on most probable recycling routes, with an emphasis on the state of the art in bioprocessing of WEEE.

Hydrometallurgical Processing and Recovery of Nickel from Spent Cathode Ray Tubes

Scientific and technological progress required for more and more advanced electrical and electronic equipment (EEE). Therefore, EEE manufacturing became one of the most important world activities, generating at the same time huge amounts of waste. In the last decades the accumulation of waste electrical and electronic equipment (WEEE) has become a global problem (Widmer et al., 2005; Babu et al., 2007; Robinson, 2009). These wastes are a threat for the environment due to their high content of toxic materials and, at the same time, they are an important source of recyclable materials, and especially valuable metals (e.g. Au, Ag, Pd, Cu, Ni, Zn). Nowadays there are various approaches for the treatment and recycling of WEEE, involving pyro-, hydro- and bio-metallurgical processes (Cui and Zhang, 2008). Among WEEE, cathode ray tubes (CRT) displays, used mainly in computer monitors and television sets, are regarded as the most polluting fraction of all WEEE (Nnorom et al., 2011). CRT recycling represents a challenge due to their high accumulation rate, proportional to the evolution of modern technologies (flat panel displays), their high content of toxic and noxious substances (heavy metals and organic compounds), improper storage, and the lack of a complete, pollution-free recycling solution. Previous studies have shown that some CRT metallic components (electron gun - EG, shadow mask) contain important amounts of Ni (25 - 45%) and Fe (50 - 70%), and small quantities of Mn, Co and Cr (Robotin et al., 2011). Ni and Ni alloys play an important role in modern technology, especially due to their magnetic and anticorrosion properties. Unfortunately, when exposed inappropriately, Ni can have negative environmental effects and can be harmful to human health (Denkhaus and Salnikow, 2002). In this context, Ni recycling from electronic waste is important for environmental and health reasons, and, at the same time, Ni recycling could be financially sustainable due to an elevated Ni market price. In the current study we propose a technological process for Ni recovery from the metallic components of CRT waste. After a preliminary separation into glass, plastic, ceramic and metallic parts, the metallic components were subjected to a magnetic separation and their composition was determined. We have chosen to recover Ni from the magnetic components due to a higher content of Ni and to avoid the contamination with Cr (present in the non- magnetic components). In the next step, chemical and electrochemical waste solubilisation was performed (Robotin et al., 2011). Apart from Ni (25-36 %), the resulting solutions contain large amounts of Fe (50-64 %) and small quantities of Co and Mn. In order to obtain metallic Ni, the solution needed to be purified, the first step being Fe removal. Fe was separated by chemical precipitation of Fe3+ under pH and temperature control. Ni was deposited on copper electrodes by electrowinning. At the same time, the electrodeposition of Ni-Fe alloys from synthetic solutions similar to those obtained by dissolution of EG waste was studied. The influence of some parameters (current density, bath composition, Ni2+:Fe2+ ratio) on the electrodeposition process was investigated.

Development of a culture collection and data bank for biometallurgical processes in india

Biometallurgical processing of minerals is a fast-developing science and is of considerable importance especially to nations like India where rapid industrialization has increased the domestic demand for metallic raw material which has to be satisfied by heavy imports. One of the ways of leading the country to self-sufficiency is to attempt to produce the metals from indigenously available low-grade/waste ores or beneficiate their quality using an appropriate technology like biometallurgy. We have developed a culture collection and data bank in respect of this technology in India for microbial leaching of copper and bioconversion of manganese. In this programme, 207 potentially-useful micro-organisms such as iron-, sulphur-and manganese-oxidizing bacteria were isolated from 60 copper and manganese mines in the country, and they were used for leaching copper and converting manganese to a better variety. These two processes were scaled-up to the 300-kg level and the isolated microorganisms were stored in an active, ready-to-use form by devising suitable preservation methods. Such a compilation of information on ores and cultures, with a centralized facility for supply of useful cultures, was referred as a ‘culture collection and data bank’. Various Indian mining industries have shown interest in trying these processes on a large scale at their mines, using the cultures and the data available from us.