Henrian Activity Coefficient of Bi in Cu-Ni Mattes

Abstract

A transpiration method was used to evaluate the Henrian activity coefficient of Bi (γ^o_Bi) in Cu-Ni mattes. Values for the activity coefficient of Bi were evaluated at 1473 K as a function of the Cu/Ni molar ratio from 0 to 1 and as a function of the sulphur deficiency (defined as SD = X_S – 1/2X_Cu – 2/3X_Ni, where X_i is the mole fraction of the i_th species) from −0.1 to 0. The dependence of γ^o_Bi on both the Cu/Ni molar ratio and SD is represented by the equations

γ^o_Bi (at SD = −0.04) = 2.12 + 0.58·(Cu/Ni) + 1.16·(Cu/Ni)²

and

γ^o_Bi (at Cu/Ni = 0.5) = 3.19 + 14.8·SD + 64.2·SD².

Analysis of the activity coefficient (γ _Bi) as a function of the trace element concentration reveals that the activity coefficient is independent of Bi content at weight percent less than 0.7. Unlike Cu-Fe mattes, the experimental results show that Ni, in a matte, can significantly reduce the volatility of Bi as represented by the low value of γ^o_Bi.

A transpiration method was used to evaluate the Henrian activity coefficient of Bi (γ^o_Bi) in Cu-Ni mattes. Values for the activity coefficient of Bi were evaluated at 1473 K as a function of the Cu/Ni molar ratio from 0 to 1 and as a function of the sulphur deficiency (defined as SD = X_S – 1/2X_Cu – 2/3X_Ni, where X_i is the mole fraction of the i_th species) from −0.1 to 0. The dependence of γ^o_Bi on both the Cu/Ni molar ratio and SD is represented by the equations

γ^o_Bi (at SD = −0.04) = 2.12 + 0.58·(Cu/Ni) + 1.16·(Cu/Ni)²

and

γ^o_Bi (at Cu/Ni = 0.5) = 3.19 + 14.8·SD + 64.2·SD².

Analysis of the activity coefficient (γ _Bi) as a function of the trace element concentration reveals that the activity coefficient is independent of Bi content at weight percent less than 0.7. Unlike Cu-Fe mattes, the experimental results show that Ni, in a matte, can significantly reduce the volatility of Bi as represented by the low value of γ^o_Bi.

On a utilisé une méthode de transpiration pour évaluer le coefficient d'activité de Henry du Bi (γ^o_Bi) dans les mattes de Cu-Ni. On a évalué les valeurs du coefficient d'activité du Bi, à 1473 K, en fonction du rapport molaire de Cu/Ni de 0 à 1 et en fonction de la déficience en soufre (définie par SD = X_S – 1/2X_Cu − 2/3X_Ni, où X_i est la fraction molaire de la ième espèce) de −0.1 à 0. La dépendance de γ^o_Bi tant sur le rapport molaire Cu/Ni que sur SD est représentée par les équations

γ^o_Bi (at SD = −0.04) = 2.12 + 0.58·(Cu/Ni) + 1.16·(Cu/Ni)²

et

γ^o_Bi (at Cu/Ni = 0.5) = 3.19 + 14.8·SD + 64.2·SD².

L'analyse du coefficient d'activité (γ_Bi) en fonction de la concentration de l'élément trace révèle que le coefficient d'activité est indépendant de la teneur en Bi à des pourcentages en poids de moins que 0.7. Au contraire des mattes de Cu-Fe, les résultats expérimentaux montrent que le Ni, dans une matte, peut réduire significativement la volatilité du Bi, tel que représenté par la faible valeur de γ^o_Bi.