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Bacteria for precious metals recovery from electronic waste

Our research line in Emerging Bio-based Technologies develops projects for the bioremediation of raw materials of strategic value by means of enzymes, microalgae, fungi or bacteria. These bioprocesses show potential for a qualitative leap in the processes of obtaining and recovering metals (such as cobalt, magnesium, rare earths or platinum group metals), both in primary raw materials (mining sector) and secondary raw materials (industrial by-products, waste from electrical or electronic equipment), as well as materials at the end of their life cycle. Lower energy needs or better performance are some of the advantages of these bioprocesses.

 

Circular economy and bioeconomy are cornerstones for building an environmentally sustainable future. Aware of this, at CETIM we support and accompany our clients and collaborators in their efforts towards sustainability, we help them to identify, research and reduce the environmental impacts generated by their products and production processes.

 

As a result of this strategy, our R&D departments are developing different researches that allow the valorisation and revalorisation of different products, by-products and waste. Our emerging bio-based technologies research line is developing projects for the bioremediation of Critical Raw Materials (CRMs) and precious metals. The use of enzymes, microalgae, fungi or bacteria to extract materials of strategic value (such as cobalt, Rare Earth Elements (REE), magnesium or platinum) are technologies still emerging and under development, but they show potential for a qualitative leap in recycling processes. Lower energy needs, greater sustainability or their possible application to low-grade minerals are some of the advantages of these bioprocesses, in addition to their environmental sustainability.

 

In projects such as BIOMAT RECOVER we investigate the extraction of CRMs (Co, W, Pr and platinum group metals) and high value metals (Ni, Au and Ag) with high purity from Waste Electrical and Electronic Equipment (WEEE), such as printed circuit boards, LCD panels and batteries. At H2020 BIORECOVER we lead the joint research of 14 entities in Europe and South Africa for the selective extraction of different CRMs, WEEE, Scandium (Sc), Magnesium (Mg) and Platinum Group Elements (PGE) from bauxite waste, low-grade ores and mixed products of secondary origin (from process waste to spent catalysts or electronic and jewellery waste).

 

In both projects, interest’s elements recovery is obtained through a triple process:

 

Pre-treatment: bio-oxidation process to enrich waste. CETIM develops the culture of selected microorganisms (based on their metal tolerance and their leaching capacity), microorganism acclimatization processes to high metal conditions, optimization of the culture parameters and we carry out metal mobilization tests. These microorganisms oxidize the non-valuable materials present in the waste, obtaining a liquid phase with these dissolved materials while the target metals will remain in the solid phase.

 

 

Etapas de proceso y biorreactor en los laboratorios de CETIM

Process stages and bioreactor in the CETIM’s laboratories.

 

 

Treatment: on the solid obtained in the previous phase, we investigate bioleaching processes with bacterial strains, fungi and/or specific enzymes, aiming to solubilize the different elements of interest. As a final product a solution that will contain the metals of interest in their soluble form is obtained.

 

Post-treatment: leachate is subjected to a bioprocess (biosorption, bioaccumulation or bioprecipitation) followed by a reduction or oxidation if necessary and depending on the needs of each of the elements recovered for final reuse. This is carried out by the selective separation of each of the interest ion from the liquid medium by means of accumulation in bacterial biomass or in specific microalgae. Finally, ions may be treated with reducing bacteria to obtain metallic nanoparticles from them, or they may be calcined/precipitated to obtain the corresponding oxides.

 

This type of process is promising – the results to date are very positive – but requires years of research for validation and optimisation. At this time, according to Dr. Maite Ruiz, Principal Investigator of our emerging bio-based technologies line, “we are working on the development of multi-stage processes with the aim of improving bioextraction yields, making the metals of interest more accessible, as well as optimizing the parameters that have the greatest influence on this type of process. It is necessary to identify the most effective microorganisms’ strains, the working conditions of the chosen bioprocesses, to adapt each one to the different nature of both the starting waste and the raw materials to be extracted, etc.CETIM seeks to obtain processes and solutions applicable on an industrial scale, in the complex real conditions of a waste treatment plant or a mine (pH, mineral complex, etc.). “Biometallurgy has less environmental impact and requires less infrastructure and resources than conventional technologies, and can be successfully applied to low grade ores“. The aim is also to obtain high recovery rates, flexibility, purity, environmental and cost efficiency, and under safety conditions, so that in the future they will be a viable industrial reality. Furthermore, we contribute to establish the knowledge of bio-mining in the European Union involving the whole value chain.

 

Strategic importance for the European Union
Another important key aspect of CRM recovery technologies is their growing strategic importance to the global economy. The European Union is aware of this and has launched various initiatives in this regard, such as the European Innovation Partnership Raw Materials, which prioritizes innovation in relation to CRMs and their recovery/recycling[1]; or Raw Materials Initiative, to encourage the sustainable supply of raw materials from European sources and to boost resource efficiency and promote recycling, or Raw Materials Week, which annually brings together in Brussels the main industrial and innovation players in the field.

 

Panel presentación proyecto Biorecover durante la EU Raw Materials Week 2019

Biorecover project ‘s poster presentation during the EU Raw Materials Week 2019.

Market’s relevance of these raw materials, including rare earths, was highlighted by our Head of ECO BIO technologies, Cristina Martínez, in an interview with Cadena SER. As Cristina commented in the interview, framed in the debate of the commercial war between China and the USA originated by the importance of critical raw materials, “rare earths are a group of 17 periodic table elements that possess unique magnetic, luminescent and electrochemical properties. These properties make them vital for the development of today’s technology and thanks to them, industry creates the technology we are in contact with every day, such as catalysts, batteries and smartphone screens or electric motors“. But these materials’ production is controlled by very few countries at world level¸ especially by China, and the internal European production is reduced or even non-existent. Therefore, industrial recovery of these materials, without depending on imports from other markets, is a strategic factor for the European economy, technology and society.

 

 

We collaborate with leading industries

CETIM, with our customers and partners, focus our current efforts in research on technologies for critical raw materials’ recovery by means of microorganisms in order to optimize and validate them at laboratory level, and thus increase their level of maturity. In order to bring its benefits to the industrial level, we have consortiums of companies that cover the whole chain: mining companies and companies with CRMs in their processes, such as MYTILINEOS or Magnesitas Navarras, waste management companies such as Ferrovial Servicios, engineering companies with expertise in recovery processes such as AlgaEnergy or Técnicas Reunidas, and industries interested in the application of recovered materials: Al-Farben, expert company in micropigments, FAE, expert in electronic components for the automotive industry, Johnson Matthey, specialty chemicals, etc. We also collaborate with expert consultants in market analysis such as Vertech and LGI and knowledge centres around the world, such as the Universities of Coimbra, Cape Town, Johannesburg, Copenhagen, or Linnaeus.

 

 

[1] https://eitrawmaterials.eu/innovation-themes/