Patent ID: 6217631
Filing Date: 2001-04-17
Classification: B01F,C22B,C23C,Y02P

Abstract:
A method of treating a body of molten metal using an impeller, the method including increasing shear forces in the body of molten metal and reducing vortex formation, the method comprising the steps of:(a) providing a molten metal treatment box having:(i) a bottom and sides joined together to contain the body of molten metal;(ii) a molten metal entrance and a molten metal exit provided in said sides, said bottom and sides comprised of an outer shell of metal and an inner layer of fused silica refractory resistant to attack by said molten metal, a second refractory liner adjacent said inner layer disposed between said inner layer and said shell of metal, said second liner comprised of a castable refractory and a thermal insulation liner provided between said second liner and said metal shell;(iii) a removable metal lid for covering said body of molten metal, said lid supported by said outer shell of metal, said lid having a first opening therein for projecting an impeller on a shaft into said body, said lid adapted for supporting said shaft and shaft rotation means, said lid having a second opening therein for removing skim accumulated on said body;(b) projecting an impeller on a shaft through said first opening into said body; and(c) treating said body by dispersing a gas therein by rotating said impeller in one direction and thereafter reversing said direction of rotation, the direction of rotation being reversed periodically.