Heap leaching of Cr/Ni-rich sludge validated at VITO

Heap leaching of a Cr/Ni-rich sludge was validated by VITO in a 1 m³ fully automated setup with recirculation of the leaching solution and continuous pH and redox adjustment.
Approximately 300 kg of sludge was granulated and placed in the cubitainer on top of an inert sand layer to avoid clogging. Based on the laboratory experimental work (in WP3), the test was started with water adjusted to pH 4 with H2SO4.
After 7 weeks of operation, the oxidizing agent Na2S2O8 was added to increase the redox potential of the solution up to 700 mV and speed up the leaching process. Due to the end of the METGROW+ project, the pilot was stopped after 2,5 months before the full completion of the leaching process. The results were in line with the laboratory test results, proving that the process can be upscaled. With the developed leaching process, approximately 80% Cr and 100% Ni can be selectively recovered from the Cr/Ni sludge without dissolution of Fe. Sorption experiments showed promising results for the recovery of Cr and Ni out of the leachate streams.


Recovery of nickel from Polish laterites validated at IMN

Three technologies for recovery of nickel from Polish laterites were validated at Łukasiewicz Research Network – Institute of Non-Ferrous Metals (Łukasiewicz-IMN).

The first technology covered the application of hydrochloric acid. In a series of operations comprised of leaching and subsequent precipitation steps, it allowed to obtain nickel and magnesium concentrates as well as to recover hydrochloric acid.

The second one was dedicated to the production of the solution containing nickel and magnesium using sulphuric acid. Both technologies included also iron removal step, essential for further material processing.

Both technologies were validated at Łukasiewicz-IMN facilities using 50 dm3 – 1 m3 leaching tanks and suitable chamber-membrane filtration presses. Sulphate solutions from second technology were subjected to solvent extraction tests. Tests were performed using a laboratory system for continuous solvent extraction composed of 8 mixer-settler units (0.5 dm3 and 1.5 dm3 each). The single test took ca. 8 hours and 15 test were done to validate the technology.

It was found that it was possible to recover over 90% of nickel contained in laterites during leaching. Solvent extraction tests allowed to recover almost 100% of nickel contained in the solution and to reduce magnesium content over 20-times.



Plasma technology was validated at a 100 kVA pilot plant in TECNALIA for two materials, an Fe-rich residue from mining (goethite sludge) and a fayalitic slag.

Preliminary thermal studies at laboratory facilities in TECNALIA proved that the pyrometallurgical treatment of those residues could be an interesting approach. The scale-up to TRL 5 in the pilot plant demonstrated the technical feasibility of the plasma technology to obtain three marketable by-products: fly ash, metal and slag.

The treatment of the fayalitic slag and the goethite sludge produced a Zn+Pb oxides containing fly-ash, a metal with Fe concentration above 95% and a slag containing Si, Al, Ca and Mg oxides, proven of interest for the production of inorganic geopolymers.

In addition, evaluation of the global viability of the process, considering also environmental aspects and economics (CAPEX/OPEX) were studied.

The experimental data obtained from the tests performed for both residues at the pilot were used by TECNALIA to develop a model for the simulation of plasma furnace based thermal treatment. An engineer from TECNALIA moved to OUTOTEC’s facilities in Pori (Finland) and optimised jointly the model using HSC Chemistry software. Additional operations such as raw material feeding, briquetting, thermal pre-treatment and gas cleaning processes were also included in the simulation.

This model was afterwards used to simulate at industrial scale the behaviour of one other material within the METGROW + project, the landfilled Zn-rich sludge material. The mass balance and the energy requirements of the process were predicted and the physical properties and composition of each stream of the process were estimated. The data obtained were used to evaluate the techno-economic feasibility of the process, giving positive results.


Heap leaching validated for low-grade laterites

TUC validated heap leaching in WP6 by taking also into a series the results of a series of activities in WPs 3, 4 and 5, involving:
– Larger column leaching tests of low-grade laterites (Ni content 0.5-0.7 %wt), using a 5 kg feed and sulphuric acid as leaching medium.
– Sequential leaching tests (i.e the PLS obtained from the first leaching column was used as leaching medium in the second column), based on the results of single tests using ores of various grade, in order to increase the content of Ni and Co in the pregnant leaching solution (PLS)
– PLS purification was carried out by precipitation and SX; mineralogical analyses and SEM studies were carried out in the precipitates and leaching residues
– Finally, the leaching residues were valorized through alkali activation for the production of alkali-activated materials (AAMs)


METGROW+ session in the Expert Forum Urban Mining and Metal Recovery from Low Value Ores and Side Streams

METGROW+ had a complete session in the Expert Forum Urban Mining and Metal Recovery from Low Value Ores and Side Streams 25.11.2019 in Helsinki. The session started with the general METGROW+ presentation by Päivi Kinnunen from VTT to have an overview of the project. The promising validation results for the nickel recovery from Greek laterites by atmospheric acid leaching and metal precipitation were presented by Elina Oksanen from Outotec. Liesbeth Horckmanns from VITO highlighted the validation results obtained for chromium-rich sludges using heap leaching technology. Finally, Yoko Dams from VITO presented the assessment methods and results for different METGROW+ technologies. Also, the METGROW+ toolbox was presented.


METGROW+ selected to the Horizon 2020 Technology Success Stories

European Commission organized the fourth edition of the EU “Raw Materials Week” from Monday 18th to Friday 22nd November 2019, in Brussels. METGROW+ was selected to the session “Horizon 2020 Technology Success Stories”, which focused on the achievements of various H2020 projects. In her talk, Päivi Kinnunen highlighted the main validation results, which have been successfully obtained for metals recovery in the project. The main outcome of the project, METGROW+ toolbox, was also presented to the audience. The tool will be available to the wider public by the end of January 2020. Several steps have been taken towards recovering metals from challenging low-grade materials, valorizing the whole mineral matrix, consuming less chemicals in the processes and developing a tool for helping in the process selection decision making. The session focusing on “H2020 Technology Success Stories” showed that several projects funded by the European Commission under H2020 are complementary and many of them have also clustered with other projects.


METGROW+ in the International Biohydrometallurgy Symposium 2019

Biological metal leaching and recovery developed in the METGROW+ project were presented in the International Biohydrometallurgy Symposium 2019. The biannual symposium focuses on different aspects of biohydrometallurgy and microbiology in mining. This year the event took place 20-23.10.2019 in Fukuoka, Japan. METGROW+ results were presented in the event by VTT’s Marja Salo and Päivi Kinnunen, and by RISE’s Karin Willquist in oral and poster presentations.


METGROW+ consortium meeting was held 25-26.9.2019 and hosted by RINA in Milan, Italy

The validations with various METGROW+ raw materials have been done or they are running to the end in the coming weeks. The demonstrations have been successful and they added information to the economic and environmental assessments and to the METGROW+ toolbox. The consortium participated in the multi-criteria assessment workshop (Figure), in which the methodology for decision making was done in practise. In the toolbox workshop, it was possible to test the actual METGROW+ tool on-line and give feedback to the development before publishing it in the final form to the public.


METGROW+ was presented at The Finnish Presidency Event

European Days for Sustainable Circular Economy taking place in the Finlandia Hall in Helsinki 30.9.-1.10.2019. The event aimed at promoting a low-carbon, climate-resilient circular economy. It enabled active dialogue with different stakeholders interested in circular economy issues. H2020 funded METGROW+ (Jarno Mäkinen on left) and ITERAMS (Päivi Kinnunen on right) projects highlighted methods, how to provide metals to the needs of the society in a more sustainable way. More information here.


METGROW+ invited students from Classical High School of Tampere to learn about raw materials

50 students from Classical High School of Tampere visited VTT Technical Research Centre of Finland to learn about the importance of raw materials and their production methods on 21st February 2019. The groups visited research laboratories in order to experience how the research in the raw materials sector is done. The tour included presentations about bioleaching low-grade ores to metal concentrates, value generation of the metals from the mine to the smelter and further to pure element, as well as different chemical measurements in practice.