In June 2007 Stollberg supplied the first Flux Feeder to CSN for testing purposes. Due to the convincing operating experience, CSN continued to use the system beyond the testing phase and ordered three additional units at the end of 2007. Three of the four Flux Feeders are in operation at the continuous casting lines 2, 3 and 4. The fourth one is used as a stand-by unit. Before the automatic systems were supplied the granulated casting fluxes were added manually.
All of the Flux Feeders at CSN are in operation 24 hours a day. They are stopped only for maintenance purposes. Each feeder applies about 1.5 t of casting powder per day – or one kilogram per minute – onto the surface of the liquid steel in the mould. The Volta Redonda works produces about 5.3 million t/year of steel.
After about eight months of operation since the first feeder was started up, experience has shown that the systems improve the quality of the cast strand as a result of a more homogeneous flux distribution in the mould, that they increase safety and simplify handling operations.
In addition, the use of Flux Feeders is more environmentally friendly because they reduce the dust load in the casting shop. The pneumatic granulate feeding system has proved highly flexible during installation and operation. It needs little maintenance while providing high availability and is very gentle to the granulate product. Experience in other mills has shown that the use of big bags instead of sacks saves up to five percent fluxes because the big bags can be completely emptied without any remaining residues.
CSN has been a customer of Stollberg for more than ten years. While the fluxes were initially shipped from Germany, since erection of the casting flux production facilities in Brazil in 2002 CSN receives the casting flux deliveries from Stollberg do Brasil.
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