Deoxidation of molten copper with a rotating graphite cylinder
- PDF / 355,680 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 30 Downloads / 239 Views
TION
THE recent potential demand for high-purity copper in electronic industries requires further improvement of the deoxidation technique of copper refining processes. The conventional vacuum degassing of inductively melted copper in a graphite crucible is a batch process of small melt volume and has several inherent disadvantages regarding the flexibility of the melt’s size and the reaction rate. On the other hand, gas and powder injection refining[1] is especially suitable for mass production, but, in the case of degassing of high-purity copper, heavy splashing due to injection can become a serious disadvantage. A need exists for a new process of molten copper degassing with more flexibility in its productivity. One of the present authors (MS) has recently proposed[2] a new degassing method called vacuum-suction degassing (VSD), and has shown promising results in experiments with molten iron decarburization by the VSD method in the low and ultralow carbon concentration ranges. In the present study, the authors examine the application of the VSD method to the deoxidation of molten copper with a very low oxygen concentration. In the experiments, the copper bath is deoxidized with a rotating porous graphite tube, the inside space of which is evacuated for the purpose of CO gas removal from the graphite-metal interMASAKI MIYATA, formerly Graduate Student with the Graduate School of Engineering, Nagoya University, is Research Engineer with Sumitomo Metals Industries, Ibaraki-ken 314-0255, Japan. MASAMICHI SANO, Professor, is with the Department of Materials Processing Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-0814, Japan. MASAHIRO HIRASAWA, formerly Associate Professor with the Department of Materials Processing Engineering, School of Engineering, Nagoya University, is Professor with the Institute for Advanced Materials Processing, Tohoku University, Sendai 980-0812, Japan. Manuscript submitted May 19, 1997. METALLURGICAL AND MATERIALS TRANSACTIONS B
face to the outer space. The reaction mechanisms in the low and intermediate oxygen concentration ranges are to be investigated in relation to the kinetic effect of CO bubbles at the reaction interface. II.
EXPERIMENTAL
The basic idea of the VSD method is illustrated in Figure 1.[2] The porous material is permeable to gas constituents but impermeable to the liquid metal. The outer space is a vacuum. The pressure drops abruptly from the static pressure in the melt to the low pressure inside the pore of the porous material surface in the vicinity of the porous material–metal interface. The locally reduced pressure at the porous material–melt interface favors degassing reactions, i.e., reactions involving the formation of gaseous reaction products, at the interface. As the degassing occurs, we count the following three types of reactions: (1) nucleation of impurities, (2) reactions between impurites, and (3) reaction between the impurities and the porous material. The gas bubbles formed at the interface are removed quickly to the outer spa
Data Loading...
