| The present work covers an analysis of the fundamental thermal phenomena which take place when 'buoyant', solid additives are injected into steel or hot metal for deoxidation or desulphurization purposes. For low melting point additives such as aluminum (for steel deoxidation) or magnesium (for hot metal desulphurization), it is found that a solid shell of the melt material will tend to fuse onto the object. Very often, the encasing shell will delay the rapid dispersion of the additive.;Aluminum wires of 6.4 to 15.9 mm in diameter were fed into steel melts while their 'apparent' weights were monitored with a novel piece of equipment. It was determined that the maximum depth of penetration of an aluminum wire fed into molten steel can be expressed as:;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);The thermal aspects of the bullet shooting method were also simulated with the above-mentioned apparatus. It was found that the aluminum was only dispersed when the shell in the vicinity of the ends of a bullet had melted back. Since the time required to melt back the shell is inversely proportional to the superheat of the melt, molten aluminum cores encased in solid shells will resurface if the superheat is too low. It was shown that by selectively applying an appropriate thermal resistance onto the surface of a bullet, this problem can be eliminated.;Two industrial methods which can be used to improve additive dispersion are the wire feeding and bullet shooting techniques. A thermal analysis of these two processes was carried out in the present study. |
