APPARATUS FOR REFINING MOLTEN METAL

摘要

In an apparatus for refining molten metal comprising combination:… a) a vessel having an insulated cover (16), at least one inlet zone and at least one outlet zone, and at least one refining compartment connected thereto; and… b) one rotating gas distributing device disposed in each refining compartment, said device comprising (i) a shaft passing through the cover (16) and having drive means at its upper end located above the cover outside of the compartment and a rotor fixedly attached to its lower end located below the cover inside of the compartment and (ii) a hollow stator (13) surrounding said shaft and fixedly attached to said vessel, the stator and shaft having a common hypothetical axis (17), said stator having an upper portion and a lower portion, the upper portion comprised of a corrosion resistant metal and the lower portion (22) comprised of graphite, the upper portion being connected to the lower portion by a corrosion resistant metal/graphite threaded joint, the cover being at least about 12,7 cm thick in the vicinity of the stator,… the improvement comprising:… (A) providing a joint which comprises a threaded male graphite piece (25) having a shoulder (26) preceding the threads and a threaded female corrosion resistant metal piece (19), the female piece being seated against the shoulder of the male piece and the cross-sectional area of the female piece, as measured immediately adjacent to the shoulder, being in the range of about 30 percent to about 50 percent of the cross-sectional area of the unthreaded section of the graphite portion (22) as measured immediately adjacent to the shoulder;… (B) providing an annular passage (23) in the unthreaded section (20) of the corrosion resistant metal portion through which a cooling gas can be passed, at least part of said passage being located perpendicular to the axis and proximate to the joint at a distance (D) therefrom about equal to the thickness (E) of the wall of the female piece in which the threads are cut and having an effective cooled area of at least about 70 percent of the cross-sectional area of the unthreaded section of the graphite portion (22) as measured immediately adjacent to the shoulder;… (C) establishing a ratio of (i) the distance (B) from the side of the cover (16) adjacent to the refining compartment to the side of the joint closest to the cover to (ii) the thickness (C) of the cover, said ratio being greater than unity; and… (D) establishing a ratio of (i) the distance (A) from the surface of the annular passage (23) closest to the shoulder (26) to the shoulder to (ii) the distance (B) from the side of the cover (16) adjacent to the refining compartment to the side of the joint closest to the cover, said ratio being no greater than about 0.35:1.