Apparatus and process system for preheating of steel scrap for melting

Abstract

The invention provides a novel preheating apparatus and method for preheating a ferrous scrap mixture prior to feeding the scrap into a metallurgical furnace, primarily using heat recovered from hot waste gases emitted from the furnace exhaust port, and simultaneously reducing contaminants from the scrap and from the waste gases, with concurrent downward flow of hot waste gases and downwardly descending scrap. The apparatus has a chamber, including a top compartment with a cold scrap input for depositing cold scrap into the top compartment and a hot waste gas inlet in flow communication with the furnace exhaust port. The chamber also has a bottom compartment with a heated scrap discharging mechanism for force delivering the heated scrap into the furnace and a waste gas outlet in flow communication with a vacuum exhaust for evacuating spent waste gas. Gas permeable gates are disposed between each chamber compartment and sequentially operate between a closed gate position and an open gate position, for concurrently receiving a gravity fed charge of scrap from the cold scrap input in a closed gate position, and during a predetermined dwell period supporting the scrap charge while hot waste gas flows downwardly from the hot gas inlet in the top compartment, permeates through the scrap charge and through the closed gates, and flows out the waste gas outlet in the bottom compartment. The gates mix the scrap as it falls and serve to control the gravitational descent of the scrap charge from the top compartment to the bottom compartment on expiry of the dwell period.