Abstract: The mouth of a metal refining vessel has a primary gas collection hood supported over it. A duct couples the hood to a gas cleaning quencher which is serially connected by a duct to a wet scrubber. A fan draws gases and suspended particulates through the system and discharges the effluent from the scrubber to a stack which burns the gas in the atmosphere. A secondary gas collection hood is supported over the first hood. The secondary hood has a duct which connects into the gas cleaning system intermediate the quencher and the scrubber. A bell damper connects the duct from the secondary hood into the intermediate duct. When the vessel is tilted away from the primary hood, the damper is opened so that gases escaping from the mouth of the vessel may be captured by the secondary hood and passed through the gas cleaning system. The secondary hood has a chain curtain which yields to allow a ladle or scrap charging box to swing over the vessel mouth when it is tilted.

Abstract: A gas collector hood is located close to the mouth of a converter vessel and has a diameter which is not much greater than the mouth of the vessel. A mixture of oxygen together with entrained powdered materials based on process requirements and a hydrocarbon fluid as cooling agent are blown through tuyeres in the bottom of the vessel and diffuse through the hot metal in the vessel. The inherently finer dust produced from the bottom-blown oxygen process requires that for proper air pollution control a non-combustion system be used to take advantage of the increased agglomerating properties of iron oxides when produced in reducing atmospheres. When blowing is initiated in this process carbon monoxide and hydrogen evolve immediately and in order to render the gases inert, air is aspirated into the gas collector hood so that an inert gas plug is formed which purges the exhaust system of combustion air.