SisAl Pilot: Silicon production with low environmental impact using secondary aluminium and silicon product streams

SisAl Pilot aims to demonstrate a patented novel industrial process to produce the Critical Raw Material (CRM) Silicon (Si) in different qualities; Metallurgical Grade Silicon (MG-Si), pure silicon (99.99 %) and Al-Si alloys, by shifting from today’s carbothermic Submerged Arc Furnace (SAF) process to aluminothermic reduction of quartz in a calcium silicate slag, producing metal/alloy and a CaO-Al2O3 slag, which is hydrometallurgically treated to produce alumina (Al2O3) and calcia (CaO). The alumina may be used as raw material in the Al electrolysis process or in other high value applications. The CaO is recycled into the making of the CaO-SiO2 slag, which is used in the reduction process. Compared with the present SAF process to produce (MG-Si), SisAl will give substantial reductions in material yield losses, enhanced valorisation of waste- and by-product streams, at a 2/3 lower energy consumption and radically lower emissions of CO2 and harmful pollutants - at a significantly lower cost. The SisAl process is a step towards more circular production compared with the current one-dimensional silicon and aluminium supply chains and enjoys the advantage of high flexibility concerning both raw materials and products, to be demonstrated in the project. For example, fine quartz can be used as opposed to lumps - enabling the utilization of low-cost raw materials that are unsuitable for traditional Si production. SisAl Pilot will bring together raw material providers, silicon- and aluminium producers/processors with SME´s/consultants/equipment manufacturers and research organizations to demonstrate the advantages of the process in four pilots, located in four European countries (Norway, Germany, Spain and Greece). The pilots will be accompanied by environmental, economic and technological benchmarking.