Production delays are a common occurrence in an integrated mill, and beaching hot metal is often a necessity. Fumes generated from beach dumping can be observed for miles, and in many cases, local environmental authorities prohibit beaching. To reduce fume from processes such as iron beaching at a much lower capital cost than a fume collection system, the Air Liquide emission control technology (Alect~(TM)), utilizing CO_2, was developed.The Alect system utilizes the physical properties of CO_2 to transform it from a liquid at 300 psi to a solid at atmospheric pressure. Liquid CO_2 is conveyed under pressure to a snow cannon, which injects the dense CO_2 snow to the areas where fume generation occurs, such as the molten metal impact points where associated turbulence and mixing with ambient air occurs. At the hot metal surface, the solid CO_2 sublimates to a gas, with a volumetric expansion of 900 times. This rapid expansion purges the air away from the molten metal and provides a much more effective air purge than other fume-suppression techniques, such as gas injection or flame suppression. Fume, which is generated from the oxidation of fine iron droplets, is thereby greatly reduced.
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