FLUID DYNAMICS OF SUBMERGED GAS-PARTICLE JETS AND INJECTION REFINING OF LIQUID METALS.

摘要

In order to model the transition of flow from bubbling to jetting flow behavior, a variety of liquids, particles and injection parameters have been used in this study to identify all the possible variables which can affect flow behavior of submerged gas-particle jets. The transition between jetting and bubbling is controlled by momentum transfer from particles to gas bubbles via the liquid phase. The ratio of drag force in liquid to buoyancy force of bubble, N(,R), can be used to predict the flow transition. When N(,R) is greater than 1300, jetting occurs. When N(,R) is less than 800, bubbling occurs. The feasibility of metal matrix composite manufacture by gas-particle injection has been investigated. Gas-particle jets could be used to make composites, if injection parameters and casting conditions are well controlled. The deoxidation of molten copper by graphite covering and gas injection have been investigated. The oxygen concentration in copper can be reduced down to 10 ppm or less by inert gas injection with graphite covering. The rate of deoxidation of molten copper by graphite with gas stirring obeys the first order rate equation and the rate constant is determined by mixed control of chemical reaction and liquid phase mass transfer. The rate constant can be calculated from the equation: 1/k = 1/k(,R) + 1/k(,L).