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ENERGIX-Stort program energi

Optimized Production Process and Biocarbon Product for use as Silicon reduction material

Alternative title: Optimalisert Produksjonsprosess av biokarbon for bruk som reduksjonsmateriale i silisiumproduksjon

Awarded: NOK 6.5 mill.

Project Number:

321598

Project Period:

2021 - 2024

Funding received from:

Organisation:

The overall target of the project was to reduce the use of fossil reduction materials in silicon and ferrosilicon furnaces. Replacing fossil carbon with biogenic carbon is key to reaching this goal. Biocarbon for use in metallurgical industry requires very specific properties. These include: - High mechanical strength to avoid excessive comminution during handling, transportation and charging to the smelting furnace. - Good mechanical strength at high temperature (above 900C) to avoid disintegration in the furnace resulting in carbon loss. - Tailored combination of density/porosity, reactivity, particle shape and particle size distribution to give good operational conditions in the smelting furnace. Elkem has directly used the fundamental knowlede gained from the R&D project to build a pilot plant to verify scale up of equipment and process to produce such product and to validate the product in large scale. The R&D questions and research tasks include: A process for agglomerating fine biochar material into lump material is key to be able to tailor a biocarbon for use in metallurgical industry. Agglomeration of minerals, metals and other materials is well known, but corresponding processes for agglomerating biocarbon materials are less developed. A key R&D task has thus been to investigate how variables in the agglomeration process affects properties like density, porosity and reactivity of the biocarbon product. The project has established models for reactivity and furnace behavior as a function of biocarbon properties. This includes kinetic models and element distribution models. These models will later be used to predict furnace behavior and will be compared to actual results from full scale trials. The project has investigated the effect of leaching of biomass to produce biocarbon or leaching of biocarbon to see the effect on ash chemistry. The effect has been found to be lower than expected. Certain ash elements are not reduced at all by such treatment. The project has given fundamental understanding of the self heating phenomenon in carbon products in general and in biocarbon products specifically. Charcoal has a very low thermal conductivity that contributed to a stronger self heating tendency. Advanced agglomerated biocarbon has much higher thermal conductivity and could be expected to have less tendency to self heating. However, the project has proved that the most important driver for self heating is exothermic surface reactions. The reactions are connected to free radicals on the surface of the biocarbon material, and that these radicals are formed when certain conditions are met during the biocarbon production process.

The project has already contributed to the increased use of biocarbon in Elkem's smelters even though this increase is moderate as today. The full effect of the learning is expected to come when first full scale plant based on Elkem biocarbon technology is established. The results have been important for the startup of the Elkem Biocarbon Pilot facility, where the first 1 ton handling test has been done at Elkems plant in Canada, and is planned for at Norwegian plants. So far, there is no indication that the reduction of 330.000 tonnes of reduced fossil CO2 emissions per year in the Norwegian Elkem plants or 3.7% of the total annual emissions from Norwegian process industry should not be achievable. The broadening of the feedstock base has not been achieved as desired. However, the understanding built through the project will help in the continuation of this work in the pilot plant operation the search and development of raw material base for the full scale plants. All of the results from this R&D project have been used in the current process setup at the pilot plant and will be further improved when implemented in the full-scale plant design.

The overall objective of the OptBioCar Project is to solve remaining fundamental Challenges in the Development of a biocarbon Production process for supply of biogenic reduction material to metallurgical industry. Elkem's strategy is to be the world's most sustainable producer of ferrosilicon and silicon alloys and through this contribute to the zero-emission society. Changing the reduction material from fossil carbon (coal and coke) to biogenic reduction materials in the production process is a key part of the strategy. Elkem is now establishing the first pilot plant for production of a newly developed biocarbon agglomerate which has spawned from earlier research efforts. OptBioCar mission is to support this development and allow the transfer from pilot, to full scale production. Specifically, methods and technologies which will broaden the feedstock base will be developed. The fundamental understanding on how the different condensates produced in the current process can be optimally tailored and utilized to further increase carbon yield will be researched. And lastly, both the fundamental understanding and the performance of the biocarbon product will be investigated using new methods developed in the project. The overall goal is that the project will fast track the transition from pilot to full-scale production by omitting the majority of bottlenecks and risks and ensure that Elkem can maintain its position as a pioneer in renewable reductants in the metallurgical segment. The ultimate goal of the Project and the process Development is to provide and prove a biogenic reduction material that has at least as good furnaceability in silicon and ferrosilicon smelters as today's fossil carbon materials.

Funding scheme:

ENERGIX-Stort program energi