Kinetics of As, Sb, Bi and Pb volatilization from industrial copper matte during Ar+O 2 bubbling
- PDF / 236,687 Bytes
- 11 Pages / 612 x 786 pts Page_size
- 57 Downloads / 159 Views
1/1/04
09:42 PM
Page 651
Kinetics of As, Sb, Bi and Pb Volatilization from Industrial Copper Matte during Ar O2 Bubbling H.S. SOHN, Y. FUKUNAKA, T. OISHI, Z. ASAKI, and H.Y. SOHN A kinetic study on minor elements removal during copper matte oxidation was designed under the presumptions of low FeO activity and of no fayalite slag formation. Copper matte with a mass fraction of Cu of 59 pct was mixed by Ar gas blowing during preheating. The matte was oxidized at 1523 and 1673 K by bubbling Ar O2 gas through a submerged nozzle. The effects of melt temperature and input oxygen content on the oxidation rate of matte and the volatilization rate of minor elements in copper matte are discussed. The competition reaction composed of the oxygen dissolution into matte and SO2 gas evolution rate results in the preferential oxidation of FeS in copper matte. The desulfurization rate of matte and the volatilization of minor elements in copper matte were primarily controlled by the mass-transfer rate through the gas film boundary layer around rising gas bubbles. The As, Pb, and Bi were significantly removed during Ar gas blowing with the volatilization rates of Bi and Pb markedly increasing with the melt temperature. However, the dependences of the volatilization rates on the input oxygen partial pressure were affected in a complicated way by the effects of the melt temperature and the reduced amount of exhaust gas.
I. INTRODUCTION
AS the high-grade mineral deposits become exhausted, copper concentrates will contain increasing amounts of minor elements such as arsenic, antimony, bismuth, and lead. The behavior of these minor elements is of great importance during copper smelting process. These elements affect adversely the mechanical and electrical properties of product copper and are the major concern as environmental pollutants. There are a number of reports[1–6] on the distribution behaviors of minor elements in copper matte converting. A minor element can be removed to the gas phase by volatilization during the converting process. Yazawa and Azakami[7] have discussed the thermodynamics of the removal of impurities from matte and copper, and reported that most of the undesirable impurities such as arsenic, antimony, bismuth, and lead in matte are not removed by oxidation, but rather by volatilization. The concept of the degree of supersaturation of minor element in gaseous phase was proposed by Itagaki and Yazawa.[8] Chaubal and Nagamori[9,10] studied the volatilization of minor elements in copper matte converting with the stepwise equilibrium simulation. They reported that the elimination of minor elements by volatilization was possible only in the slag-making stage of converting. The copper matte converting process proceeds by a continuous supply of air or oxygen-enriched air. Exhaust gas from the P-S copper converter goes to the acid plant. Therefore, the kinetics study on the minor element behavior is also indispensable to understand the industrial copper smeltH.S. SOHN, Assistant Professor, is with the Department o
Data Loading...
