Copper deoxidation kinetics utilizing carbon monoxide
- PDF / 589,465 Bytes
- 6 Pages / 603 x 783 pts Page_size
- 108 Downloads / 206 Views
STER is Professor, Department of Metallurgical Engineering, Michigan Technological University, Houghton, MI49931. This paper is basedon a portion of the dissertation submitted by R. J. Andreini in partialfulfillment of the requirementsfor the degree ofDoctor of Philosophy at Michigan Technological University. Manuscript submitted April 9, 1976. METALLURGICAL
TRANSACTIONS B
c r e a s e d as the bubble size decreased. Increasing the flow rate of flushing gas was also observed to inc r e a s e the r a t e . They showed that the r e m o v a l of hydrogen from liquid aluminum by a flushing gas technique is a nonequilibrium process and postulated that the rate of removal could be described in t e r m s of liquid phase mass transport control. The mass t r a n s fer coefficient for the removal of hydrogen from liquid aluminum at 700°C was found to be equal to 3.9 × 10-2 cm s-1. T h e i r work, however, used arbitrary bubble sizes (bubble radius assumed to be twice that of the inlet tube radius) to estimate the bubble velocities and rise times in the melt. Davenport3 studied the absorption rate of oxygen in s i l v e r at 1010°C, but experimental difficulties led to an overall uncertainty of approximately =~30 to 40 pct in the measurement of mass transfer coefficients. Guthrie and Bradshaw4 studied the behavior of l a r g e bubbles r i s i n g in molten silver. They bubbled nitrogen through the melt t o test the behavior and accuracy of the experimental system and studied the kinetics of the absorption of oxygen in liquid s i l v e r at 1020°C. Spherical cap shaped bubbles were assumed and r e s i d e n c e times were determined by monitoring pressure fluctuations above the melt in a closed system. No d i r e c t measurements of bubble shapes were done in this study. Dumping-cup techniques were used in both of the studies described in this paragraph. Interest in the kinetics of the deoxidation of copper by gaseous reduction has increased since the development of the Phelps Dodge process to deoxidize copper u s i n g reformed natural gas injected into the melt from submerged tuyeres. 5 Brantley and Schack6 studied propane, natural gas, reformed natural gas, carbon monoxide, and butane for possible use as g a s e s for the deoxidation of copper in a study done by the U.S. Bureau of Mines, and found butane t o be superior t o all others tested. Henych e t a l7 have performed g a s e ous deoxidation of molten copper using ammonia (patented Czech process). Themelis and Schmidt8 have studied the kinetics of the deoxidation of liquid copper at 1170°C using a jet of CO gas. The kinetics of the process were examined on a laboratory s c a l e by varying orifice diameter, d e p t h of submersion in the melt, and gas velocity. A gas chromatograph was used to analyze the exit gas. They found that the rate of deoxidation increased as the diameter of the orifice increased, and concluded that gas phase mass transfer controlled the reaction VOLUME 8B, DECEMBER 1977-633
rate at oxygen concentrations g r e a t e r than 0.1 wt pct. Below thi
Data Loading...
