Metal processing chains are complex and involve a wide range of treatment processes depending on their end use. While it is particularly difficult to find reliable data on the quantities of material used and transformed at each stage (due to a lack of publication and to industrial secrecy), public authorities need this information to implement environmental and economic policies. The aim was to meet this need by estimating the silicon flows in the silicon metal processing chain for 2019, and to represent them in the form of diagrams that could be used by a wide audience.
After the collection and compiling of a database, all the flow data were made consistent at a global level, from the extraction of silica to the shaping of semi-finished products containing silicon metal. Based on this work, a flow chart and a map of annual production and trade were produced.
The flow chart shows the main processing stages and corresponding flows. In particular, the map illustrates China’s massive exports of metallurgical grade silicon, and its huge imports of solar and microelectronic grade silicon. An analysis published on Minéralinfo.fr (French mineral resources platform) shows that the situation is changing, with China moving towards self-sufficiency in high-purity silicon metal.
Using the results
These results, publicly available and free of charge on the Mineralinfo.com platform in an article in the Ecomine section entitled: “Chaîne de transformation du silicium métal, recyclage et montée de la Chine sur le marché du polysilicium en 2019” [Silicon metal processing chain, recycling and China’s rise in the polysilicon market in 2019], are used directly by COMES (Comité des Métaux Stratégiques) and French silicon metal stakeholders. A scientific article on this subject is also being prepared for publication.
We would like to thank the French startup RoSi Solara company specialising in the recycling of Si from photovoltaic panels, which provided us with a lot of data and information.