Pyrolysis of wood optimised for production of energy and tailor-made biocarbon for silicon production
Elkem has a pronounced goal for using 20 % renewable carbon in the mix of reduction materials in the production of silicon and ferrosilicon alloys in Norway within 2021 and 40 % within 2030. We reached the 20 % goal in 2018, and now work to reach our 2030 milestone. To reach this goal Elkem will develop a new industrial process for biocarbon tailor-made for silicon and ferrosilicon production processes.
Partners: Elkem, Sintef Energi, Paper and Fiber Research Institute (PFI).
Funding period: 2017-2021
Traditional charcoal production has millennial roots and has in principle remained unchanged although many varieties of pyrolysis furnaces have been used through time.
Pieces of wood are heated without (or with very limited) access to oxygen. That drives off water and volatiles as vapours and leaves a charcoal typically containing 70-90 % carbon.
The 3 main goals for the PyrOpt-project is to improve:
1. Biocarbon product quality
2. Process performance of the pyrolysis technology
3. Process integration between the silicon and pyrolysis technology
The R&D project PyrOPT
The volatiles can be burned to produce energy or condensed to produce other liquid products such as fuel or functional chemicals. The traditional charcoal production is called slow pyrolysis and favours carbon formation.
Furthermore, the project is investigating the agglomeration of fines as a part of tailoring a biocarbon for metallurgical industry. That also opens up for looking at intermediate pyrolysis that is expected to yield more fines than slow pyrolysis, but at the same time gives better conditions for upgrading the vapours.
Suitable for silicon and more sustainable
Metallurgical industry has so far been limited to the charcoal quality produced for the barbeque market. To create a biocarbon suitable for silicon production, an optimal process for a tailored biocarbon, where the negative properties are minimised, and the beneficial properties are enhanced needs to be developed.
Furthermore, the production should take place in the most sustainable way.This means that every kilogram of biomass must give maximum amount of usable solid carbon, all side streams must be utilised and energy demanding processes such as drying wood should be driven by available energy sources. It would thus make sense to put the biocarbon production at an existing smelter to integrate energy flows in a good way.
The project is also investigating the agglomeration of fines as a part of tailoring a biocarbon for metallurgical industry. That also opens up for looking at intermediate pyrolysis that is expected to yield more fines than slow pyrolysis but at the same time gives better conditions for upgrading the vapours.