The thermodynamic activities of the components of iron-copper mattes at 1300 degrees Centigrade

Chatchai Somsiri, Purdue University

Abstract

The thermodynamic properties of copper matte have been studied at 1300$\sp\circ$C by equilibrating mixtures of Cu$\sb2$S and FeS with gas mixtures (CO-CO$\sb2$-SO$\sb2$) of known pressures of S$\sb2$ and O$\sb2$. The conditions under which the equilibrations were carried out were log P$\sb{\rm O\sb2}$ = $-$8.5 to $-$9.5 and P$\sb{\rm S\sb2}$ = 0.005-0.0158 atmosphere with W$\sb{\rm Fe}$ of 0.1, 0.3, 0.5 (W$\sb{\rm Fe}$ = wt%Fe/(wt%Fe + wt%Cu)). It was observed that at fixed sulfur pressure, the activities of both copper and iron decrease with increasing oxygen pressure. Increasing the sulfur pressure at constant the partial pressure of oxygen and W$\sb{\rm Fe}$ also decreases the activities of both components. The activities of the sulfide components increase with increasing sulfur pressure as do the activities of the oxides with increasing oxygen pressure. The activity of FeS decreases slowly with increasing oxygen pressure but more quickly with a decrease in W$\sb{\rm Fe}$. The solubility of oxygen increases with increasing W$\sb{\rm Fe}$ at a constant sulfur pressure and with increasing oxygen pressure at constant W$\sb{\rm Fe}$ but decreases with increasing sulfur pressure. The oxygen content of the matte can be expressed by:$$\rm wt\%oxygen = 2.59\ P\sbsp{O\sb2}{0.225}P\sbsp{S\sb2}{-0.18}\ (1 +9.0\ W\sb{Fe})\sp{1.86}$$ An increase in sulfur pressure increases the sulfur content of the matte. Temkin and Flood activities have been calculated from the experimental data. It was found that the matte neither fully conforms to Temkin or Flood behavior. The activity of Cu$\sb2$S was found to be close to the values predicted by Flood's model at low oxygen pressure. At high oxygen pressure the Cu$\sb2$S activity decreases to values predicted by Temkin's model.

Degree

Ph.D.

Advisors

Gaskell, Purdue University.

Subject Area

Materials science

COinS