Gas injection method

Claim 1

A process for introducing gas into molten metal in an apparatus comprising a. a first metallic bath chamber; b. a second metallic bath chamber; c. means for flowing metal from the first metallic bath chamber to the second metallic bath chamber, through a metal transfer conduit, said metal transfer conduit being at least partially submerged in the first metallic bath chamber; d. a two-ended gas injection conduit having one end submerged within the first metallic bath chamber, the submerged end of the gas injection conduit being connected to the metal transfer conduit, the gas injection conduit being so constructed and arranged that the metal of the first metallic bath chamber is flowable past the submerged end of the gas injection conduit so as to contact the gas within the gas injection conduit and permit passage of the gas from the gas injection conduit to the metal transfer conduit, the gas injection conduit having an unsubmerged end opposite the submerged end of the gas injection conduit; and e. means for providing gas to be introduced into the molten metal into the unsubmerged end of the gas injection conduit, comprising the steps of: 1. introducing a gas to be injected into the molten metal, into the two-ended gas injection conduit, one end of which is submerged within the first metallic bath chamber and connected to the metal transfer conduit between the first and second metallic bath chambers; while 2. flowing the molten metal from the first metallic bath chamber through the metal transfer conduit to the second metallic bath chamber, past the submerged end of the gas injection conduit connected so as to connect the gas within the gas injection conduit and permit passage of the gas from the gas injection conduit to the metal transfer conduit; and 3. passing the gas from the gas injection conduit into the metal transfer conduit and into the flowing molten metal in the metal transfer conduit.