Metal loss to slag: Part II. oxidic dissolution of nickel in fayalite slag and thermodynamics of continuous converting o
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concept of oxidic and sulfldic dissolution of copper in sulfur-containing slags has been developed in the previous work to explain the observed high solubilities of copper in r e v e r b e r a t o r y slags. ~ The distinction between oxidic and sulfidic dissolution of copper is only imaginary because copper in slag is assumed to be in the form of copper ion in both cases, but it nevertheless a s s i s t s in understanding various aspects of copper loss to slag. On the basis of this concept, the sulfldic solubility of copper from high-grade matte decreases with decreasing activity of iron sulfide, or with increasing copper content of matte. Thus, it may be assumed that the metal losses to slag occur mainly in the oxidic form toward the finishing blow of nickel-copper matte converting. Under such conditions the dissolution of nickel and copper may be a s s e s s e d based on solubility data established for sulfur-free slags. Data for copper solubility are avatlablefl 'a'4 Nickel solubility was measured in the present study. In the converting of nickel-copper matte, the t e m p e r ature is normally about 1270~ 5 and typical Fe/SiOs ratios in the slag are 1.8 (Falconbridge) s and 2.0 (Copper Cliff)fl The ratio is 1.5 in fayalite slag saturated with silica and magnetite. ~ These Fe/SiO2 ratios suggest that the solubility of nickel in slag during converting cannot be investigated using silica crucibles. A condition close to silica saturation may prevail in r e v e r b e r a t o r y smelting, but in this the slag should contain sulfur. For silica-unsaturated fayalite slags, the choice of a crucible becomes somewhat more difficult. Fortunately, the solubility of nickel can be determined using a nickel crucible, which has the added advantage of being applicable not only to simple fayalite slag but also to alumina- or lime-bearing slags. The experimental part of this study consisted of determining the nickel content in silica-unsaturated slag equilibrated with a pure nickel crucible under a COM. NAGAMORI,formerlywith Noranda Research Centre, Pointe Claire, Quebec, is now with Centre de Recherche industrielle du Quebec, Complexe Scientifique, Ste-Foy,Quebec, Canada. Manuscript submitted April 16, 1973. METALLURGICALTRANSACTIONS
COs atmosphere. The discussion includes a prediction of the solubilities of nickel and copper in slag under various conditions of b e s s e m e r matte converting. EXPERIMENTAL Two fayalite slags having Fe/SiOa ratios of 1.51 (33.8 pct SiOs, 1.4 pct Fe2Os, 64.8 pct FeO) and 1.97 (28.2 pct SiO2, 2.4 pct F%Os, 6g.4 pct FeO) were p r e pared by premelttng ferrous oxide, f e r r i c oxide and silica (reagent grade) in iron crucibles under a neutral atmosphere. ~ Carbon monoxide (99.5 pct) was passed through packed towers of copper pellets (hydrogenreduced BASF R3-11 catalyst) maintained at 300~ to remove oxygen, soda lime to remove carbon dioxide, and phosphorus pentoxlde to remove water vapor. Carbon dioxide (99.99 pct) was similarly purified in the absence of the soda lime tower. The gases were then mi
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