A EU-funded project has pioneered new technologies, and new combinations of existing ones, to recover chromium and other metals from steelmaking by-products with high efficiency.


Chromium,vanadium, molybdenum and niobium: these four metals are crucial for the European industry. But they are almost exclusively mined and produced outside Europe – especially in China, Brazil, South Africa, Russia, Kazakhstan and Turkey – making the EU highly dependent on import. 

On the other hand, Europe has large quantities of those metals trapped in industrial by-products such as slags from steel, stainless steel and ferrochrome production. These slags are used mainly as aggregates in the construction industry, with small fractions even being landfilled. 

For four years, the partners in the CHROMIC project have worked to unlock the potential of these resources, in the end taking important steps towards the development of new sustainable ways of metal recovery and a near-zero-waste recycling of the entire slag- material. 

New technologies and smart combinations of existing ones have been developed and tested and applied to the three crucial steps of the recovery process: pre-treatment, selective leaching and selective metal recovery. A comprehensive study was undertaken to characterize the initial materials in more detail, prior to the recovery investigations.

The project succeeded in extracting over 95 % of chromium and lower amounts of the other three elements, using alkaline roasting with conventional or microwave heating  and water leaching (where the metal present in the solid mixture is dissolved into water). Heap leaching resulted in lower metal recovery, but might still have potential as lower cost and impact alternative for specific streams. 

The resulting solution (leachate) was treated by a combination of methods to separate valuable elements from impurities in the solution. The entire process reaches at least 85 % overall efficiency in recovering chromium. 

Ultimately, from the results of the tests performed during the technology validation stage, it was possible to estimate that (at least) 25000 tonnes of chromium per year can be recovered in Europe through the CHROMIC process. Potentially, thanks to CHROMIC, in the future the steel slags can be considered as metal deposits. 

However, a key remaining challenge is the valorisation of the treated matrix. The overall assessment performed in CHROMIC showed that this is a crucial factor for the economic and environmental sustainability of the process. Further optimization of the treatment tested in CHROMIC is needed to fully prevent the toxic form of chromium – Cr(VI) – leaching from the treated residue. The CHROMIC processes were shown to have potential in particular for waste streams that are currently landfilled due to Cr leaching. 

Beside technology-focused activities, CHROMIC also included an assessment of the impact of these technologies on the economy and – in a broad sense – on society. Through participatory events such as workshops and focus groups, CHROMIC collected the views and expectations of European citizens about the occupational, environmental and health aspects of metal production and recovery. The insight collected through the participatory events is meant to support researchers, the metal industry, EU policy makers and regulators in taking future decisions and steering further research, with the aim of increasing citizen’s awareness and gaining societal trust, hence preparing a path for successful market application of the system process and technologies introduced by CHROMIC. 

In all, the CHROMIC project has contributed to set the way towards the realization of a circular economy for critical raw materials, which has the potential to bring significant economic and environmental benefit to the European society.

Our project coordinator Liesbeth Horckmans (VITO) will be speaking at the 7th PROMETIA Scientific Seminar, which will take place online on 10th December, 9:00-16:30 CET. This year’s seminar will report on the raw materials community’s main results and challenges that remain to be addressed in the next Horizon Europe research and innovation programme.
Horckmans will present the CHROMIC project at 11.25 during the session titled “From waste to resources”.

For more information about the event and agenda, please visit

The final conference of the CHROMIC project was held on November 19th. The full event registration is available below.

The order of the interventions in the video is as follows:

2:25 – Welcome by Marcin Sadowsky (European Commission)

9:04 – CHROMIC concept, goals and key results, presented by Liesbeth Horckmans (VITO, project coordinator)

18:20 – Preparing the slags for further treatment through physical separation, presented by Lena Kaipia (MEAM), Fero Kukurugya (VITO), Robert Moeckel (HZDR)

36:44 – Getting what we want, and only what we want: selective metal extraction from steel slags, presented by Pavel Ivashechkin (BFI)

51:27 – Purification and up-concentration to metal products, presented by Norman Kelly (HZDR), Elena Seftel (VITO), Lubomir Pikna (TUK)

1:22:16 – Putting it all together – flowsheet integration and validation, presented by Frédérique Bouillot (Orbix)

1:36:26 – Is it worthwhile? Integrating economic, environmental and health and safety assessment Koen Oorts (ARCHE)

1:56:03 – Metals and the circular economy: what do the people think? Presented by Federica Manzoli (formicablu)


The materials shown by the WP leaders and researchers involved in the project are also available here:

Koen Oorts (ARCHE, WP1 leader) presentation

Lena Kaipia (MEAM, WP2 leader) presentation

Pavel Ivashechkin (BFI, WP3 leader) presentation

Norman Kelly (HZDR, WP4 leader), Elena Seftel (VITO), Lubomir Pikna (TUKE), Pavel Ivashechkin (BFI) presentation

Frédérique Bouillot (Orbix, WP5 leader) presentation

Federica Manzoli (Formicablu, WP6) presentation




The final online conference of the CHROMIC project will take place as an online event on 19 November 2020 at 10 am.

This is the agenda:

10:00 – Welcome

Marcin Sadowsky (European Commission)

10:05 – Introduction – CHROMIC concept, goals and key results

Liesbeth Horckmans (VITO)

10:15 – Preparing the slags for further treatment through physical separation

Lena Kaipia (MEAM), Fero Kukurugya (VITO), Robert Moeckel (HZDR)

10:30 – Getting what we want, and only what we want: selective metal extraction from steel slags

Pavel Ivashechkin (BFI)

10:45 – Purification and up-concentration to metal products 

Norman Kelly (HZDR), Elena Seftel (VITO), Lubomir Pikna (TUK)

11:05 – Putting it all together – flowsheet integration and validation

Frederique Bouillot (Orbix)

11:20 – Is it worthwhile? Integrating economic, environmental and health and safety assessment 

Koen Oorts (ARCHE)

11:35 – Metals and the circular economy: what do the people think?  

Federica Manzoli (formicablu)

11:45 – Q & A 


We are pleased to invite you to the final online conference of the CHROMIC project, which will take place as an online event on 19 November 2020 at 10 am.

Creating a circular economy – where all resources are kept at the highest possible level of functionality and value at all times – is key to building a sustainable future, where innovation and economic growth can happen without further depleting the planet’s resources.

The CHROMIC research project – funded by the European Commission through the Horizon 2020 programme – aimed at creating building blocks of such an economy, focussing in particular on the metal industry. Over four years of work, It has investigated the selective recovery of  Chromium (Cr), Vanadium (V), Molybdenum (Mo) and Niobium (Nb) from metallurgical slags. These four metals are crucial for the competitiveness of the manufacturing sector and the innovation potential of high-tech sectors. Ensuring their steady supply is of strategic importance for the European industry.

During the conference, the CHROMIC partners will present the project results both at process and flowsheet level – from the preparation of the slags to their treatment, up to the purification of the final product and the valorisation of the residue.

These are all important first steps towards a true circular economy for the metals studied in CHROMIC, as well as for other critical raw materials.

The conference will also present the results of the economic, environmental and health & safety assessment of the processes studied and materials produced, as well as of participatory events (workshops and focus groups) that allowed CHROMIC to collect the views and expectations of European citizens about the occupational, environmental and health aspects of metal production and recovery. At the end, an interactive Q&A session will allow participants to share their perspective on the project.

Please register at this link:

in order to attend the conference.

Please feel free to forward this invitation to your colleagues and contacts.

We are looking forward to meeting you online – in the meantime do not hesitate to contact us if you need more information.


19 November 2020


Introduction – CHROMIC concept, goals and key results


Preparing the slags for further treatment through physical separation

This session will show how a combination of magnetic and density separation can up-concentrate Cr in an enriched fraction, while producing also metallic particles for direct reuse. Concentration of Cr is increased up to 3 times, while simultaneously reducing the amount of material to be leached.  


Getting what we want, and only what we want: selective metal extraction from steel slags

Selective alkaline leaching was chosen to extract metal from slags and make reuse of the residual matrix possible, avoiding the generation of large amounts of new waste streams. Different methods were evaluated, with traditional roasting allowing leaching rates of 100% for Cr and 33 % for V. Microwave roasting offers slightly lower rates, but is faster and more energy-efficient. 


Purification and up-concentration to metal products 

This session focusses on the separation and enrichment of the target elements from the leachates, and the transformation into final products. Two flowsheets will be presented: in one, with precipitation as a final step, a 99.99% removal of Cr with a purity of >99% was achieved. In the other, electrocoagulation resulted as a final step resulted in a complete removal of Cr.


Putting it all together – flowsheet integration and validation

The final step was to combine and upscale the best lab techniques identified in the three previous ones. Thanks to this process, from complex, low-grade waste streams, it could possible to recover more than 25,000 t Cr/year in Europe. Moreover, the residual matrix can still be carbonated for its valorisation as a construction material.


Is it worthwhile? Integrating economic, environmental and health and safety assessment 

Throughout the project, the economic, environmental and health and safety aspects of the processes studied and materials produced were assessed. When compared to current standard technologies, the economic viability and environmental friendliness of the integrated flowsheets strongly depends on the value of the starting material and the potential valorisation of the residual matrix materials.


Metals and the circular economy: what do the people think?   

Through three series of participatory events involving different stakeholders in four European countries, the CHROMIC project has gauged the level of knowledge, expectations and concerns of ordinary citizens, professional stakeholders and students when it comes to reinventing the metal value chain and orient it towards a circular economy. 



Interactive session – Q & A 

12:00 End of event


The research carried out in work packages (WPs) 2,3 and 4 constitute the technological core of the CHROMIC project, where innovative methods and processes to extract the target elements Cr, V, Nb and Mo from slags are developed and tested. As for the first stage of any research, all this happens in the labs, and it is compartmentalized in different activities focused on reaching different targets that, once pieced together, will form an end-to-end stream – from the raw material to the final product. To get there, the implemented processes must be tested as a whole and with larger quantities of materials in a production-like environment (upscaling and validation): this is what happens, in a nutshell, in WP5.


To get a more detailed picture of the stage of the project in which the research effort culminate, we talked to Frédérique Bouillot, research and development engineer with Orbix, a service provider company specialized in slag treatment for the steelworks and leader of WP5. What follows is an account of what Bouillot told us about the work that has been done at Orbix.


As mentioned, the aim of WP5 is to validate the identified metallurgical processes. That means testing the processes selected at lab scale with larger amounts of materials and bigger equipment, and performing all the steps of a process (flowsheet) one after the other, the stream coming out of a unit operation being the input of the next one. In CHROMIC this validation procedure takes place at “Technology Readiness Level” (TRL) 5: the Technology Readiness Level is a standard method to estimate the maturity of technologies and ranges from level 1 (defined as “Basic principles observed”) to level 9 (“Actual system proven in operational environment”); level 5 means the technology is “validated in relevant environment”. In WP5 the selected processes are tested on equipment that can be upscaled at industrial level.


To do so, Orbix received data from the WPs that studied separately each step of the process. WP2 gave information about the physical pre-treatment of the material; WP3 indicated how to proceed with the leaching step; and WP4 provided the relevant data for the recovery of the target elements from leachates. All CHROMIC partners are thus involved in WP5: BRGM for the preparation step; MEAM and FEhS for roasting; TUK for leaching; HZDR for metal recovery; VITO, FehS and Orbix itself for the valorization of the residual (metal-depleted) matrix. Moreover, Orbix shares information with the partners in charge of the assessment of the whole process (Arche and VITO – WP1), and with BFI, whose task is to calculate the parameters for the industrial scale. Importantly, the information collected and the general assessment performed in WP1 take into consideration not only the technical efficiency, but also the environmental and economic aspects involved in the process to validate.



Photo shibang from Pixabay


On 18th November 2019, the CHROMIC project was invited to present in the “Horizon 2020 Technology success stories” at the Raw Materials week (18-22 November 2019) in Brussels.



After a brief introduction on the overall CHROMIC concept, the talk (given by coordinator Liesbeth Horckmans) focused on the technological challenges and the importance of ensuring economic and environmental sustainability of the developed technologies. The key issues identified by the 1st iteration of the integrated assessment were discussed, and some examples were given of how these results were used to further improve the processes.


The full programme, presentations and photos are available for download at


“How to define the impact of new technologies?” was the title of a workshop on Sustainability Assessment (SA) organized on the 21st of November 2019 in Brussels by NEMO in collaboration with CHROMIC, METGROW+ and NEW-MINE, as a Satellite Event to the 4th Raw Materials Week. Approximately 20 participants from academia, research, industry and government discussed the challenges and future of sustainability assessment in the field of raw materials and beyond. The present article reports on the key lessons learned from the presentations and lively debate, and looks forward to the next events in this clustering track.


On 22nd November 2019 CHROMIC joined a wide group of EU H2020 projects to host a satellite event of the EU Raw Materials Week on “Public Acceptance and Social Impact of Mining and Mineral Recycling in Europe”.

The workshop aimed at setting a debate and proposing recommendations on how to improve public acceptance of mining activities, in a society in which these are – though essential for a transition to a low-carbon economy – often confronted with a negative reputation.

The satellite event was hosted by the projects NEMO, CROCODILE, TARANTULA, SecREEts, INFACT and CHROMIC itself and gathered representatives from industry, government, NGO, local citizens group, academia and international institution, who shared their points of view and provided recommendations before engaging in a lively debate on the topic of social acceptance with the numerous attendees of the event.

A detailed account of what emerged from the discussion can be found on the NEMO website at this page:


On 21st November, CHROMIC will participate in the satellite event of the Raw Materials Week 2019 named “How to define the impact of new technologies? A workshop on Sustainability assessment”. The workshop will gather a broad cluster of EU H2020 projects such as METGROW+(, NEMO( and CHROMIC itself, to discuss important issues regarding the economic sustainability and the beneficial impacts for the environment and for the whole society of the processes that are being developed to recover and valorize raw materials.

Questions such as how to determine the impact of resource recovery versus landfilling for such new processes and technologies will be presented and carefully addressed in an interactive debate aiming to formulate policy recommendations.

The event will take place at Le Plaza Hotel, Adolphe Maxlaan 118/126, 1000 Brussel.

To register, visit this page:

The programme of the workshop is the following:

14.00: Welcome and introduction to the workshop

14.15: Sustainability in recovering metals from secondary resources: Approach and lessons learned in METGROW+ and CHROMIC (Yoko Dams, VITO and Koen Oorts, ARCHE)

14.35: Sustainability in the mining sector: Approach and lessons learned in NEMO (Andrea di Maria, KU Leuven)

14.50: Sustainability in enhanced landfill mining: Approach and lessons learned in NEW-MINE (Karel Van Acker, KU Leuven)

15.00: Summary and common issues

15.15: coffee break

15.45-16.45: Interactive discussion

16.45: wrap-up and outlook to next event

17.00 – 18.00: networking cocktail

This project received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement n° 730471

effiCient mineral processing and Hydrometallurgical RecOvery of by-product Metals from low-grade metal contaIning seCondary raw materials