Innovative pilot for Silicon production with low environmental impact using secondary Aluminium and silicon raw materials

Project Information

SisAl Pilot

Grant agreement ID: 869268

DOI

10.3030/869268

Project closed

EC signature date 20 April 2020

Start date 1 May 2020

End date 31 October 2024

Funded under

• SOCIETAL CHALLENGES - Climate action, Environment, Resource Efficiency and Raw Materials

Total cost

€ 14 378 999,33

EU contribution

€ 11 942 623,43

Coordinated by

NORGES TEKNISK-NATURVITENSKAPELIGE UNIVERSITET NTNU
Norway

Periodic Reporting for period 3 - SisAl Pilot (Innovative pilot for Silicon production with low environmental impact using secondary Aluminium and silicon raw materials)

Reporting period: 2023-05-01 to 2024-10-31

Summary of the context and overall objectives of the project

SisAl Pilot aims to demonstrate a novel industrial process at TRL 6-7 for producing the Critical Raw Material (CRM) silicon (Si) in different qualities; Metallurgical Grade (MG-Si, >98%), high purity silicon (HP-Si, >99.9%), Solar Grade (SoG-Si, >6N) and Al-Si alloys – along with Metallurgical Grade Alumina (MGA) and/or High Purity Alumina (HPA). SisAl represents an environmentally and economically sustainable alternative to today’s carbothermic reduction process in the Submerged Arc Furnace (SAF), allowing Si production in an increasingly carbon-lean Europe.

For silicon production, the short-term solution of using bio-carbon sources as quartz reductants is challenging due to the extensive competition/high prices for this resource for use in chemicals, fuels etc. As such, and in light of increased focus on circular economy, the use of secondary aluminium sources as reductants is more relevant than ever. Underlying Si supply issues to the EU from China have also worsened, making EU industries vulnerable in both the short and long term.

The overall objective of SisAl Pilot is to scale up and demonstrate a new, carbon clean European technology to produce silicon and silicon alloys, along with metallurgical grade alumina (MGA) and high purity alumina (HPA), at TRL 6-7, validating raw materials and product quality, environmental impact and economic parameters to lay the ground for commercialisation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

After 4.5 existing years, the SisAl Pilot project is coming to an end. These years have been filled with lots of lab and pilot-scale experiments both in pyro and hydro, intense discussions about LCA and future business cases and last but not least incredible memories from project meetings around the globe.

Highlights from the WPs:
WP1 Raw Materials: SINTEF and Orykton (subcontractor) assembled an extensive raw material map for SisAl. This has given us a better understanding of the scrap market and the type of Al scrap being exported from Europe and the pricing for potential silica and lime sources.

WP2 Aluminothermic reduction: 3 large pilots for MG-Si/AlSi (Elkem, RWTH, Mintak, FRey, Wacker, Erimsa and Hydro) and 1 medium scale pilot for SoG-Si (Silicor and RU) have shown that this is not just possible in small scale but also in large scale! We have also managed to illustrate challenges in refractories, tapping etc. which is invaluable for scale-up activities. Also complex, next level modelling of reactors and processes have been done (SIMTEC and CITMaga).

WP3 Slag valorisation/Alumina production: 2 very challenging pilots!
• Alkaline route (METLEN, NTUA, NTNU): Next level (from the EU funded projects Ensureal (ID#: 958307) and Removal (ID#: 776469)) understanding of the challenges (SiO2, CaO/Al2O3 ratio etc) in obtaining MG-Al2O3 from SisAl slag.
• Acidic route (METLEN, NTUA and SiQAl): Pioneering work on successful production of 4N HPA.

WP4 and WP5 Environmental and Economic assessments: Seamless collaboration to secure best possible/relevant assessments of environmental and economic performances (BNW-Energy, NTNU, HZDR, SBC and DOW). A special thanks to Befesa for providing LCA Al recycling data!
• Learnings from constructive «arguments» on system boundaries, allocations of environmental loading, CAPEX etc.
• Landing CAPEX for non-industrial processes is not trivial...
• Parameter sensitivity studies are often more constructive/valuable than attempts at exacting values
• Continuously developing/updated process flowsheets are essential for both E&E assessments

WP6 Communication and Dissemination: CTECH and INNEN has kept us up to date on social media/on-line and showed us off at various opportunities, kept a record of our dissemination and communication activities. Also, a special thanks to Science Business and NTNUs Brussels office for helping us organising the thought-proactive roundtable event titled “Critical raw materials and circular economy: A new way forward for Europe?”.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

In SisAl Pilot five business cases have been evaluated both from an experimental (lab and pilot), environmental and economical point of view and four of these show promising results for implementation at industrial scale. The SisAl process has proven to be flexible and robust, and it can be designed to produce different silicon grades (MG-Si and SoG-Si). and alumina grades (MGA and HPA) The latter depending on which hydrometallurgical process route that is followed alkaline or acidic leaching, respectively. For the pyrometallurgical part, two process concepts have been evaluated i) a circular process and ii) an alternate process. Flow sheets for the production of solar-grade silicon (SoG-Si) and Al-Si alloy have also been developed.

Illustration of industrial symbiosis between the silicon and alumnium industries

Pilot trial at Elkem

Schematics of the SisAl process