Hokkaido,The thermodynamics of manganese in high MnO slags at hot metal pretreatment temperature were investigated. The CaO-MnO-Si02-P02,5(-MgO. FetO

The CaO-MnO-Si02-P02 5(-MgO. FetO) slags were equilibrated with liquid copper alloys in a molybdenum crucible under a flowing C02/H2atmosphere in the temperature range of 1 573 to 1 673 K.The activity coefficient of P02.5, ypo,~, and the phosphate capacity, Cpo~-= (o/.PO~-)/p~;2p~;4• of the slags were expressed as follows: log *lpo, ==~2 .59{ ("/oCaO) + 0,33 (~/oM -0.77 ("I.PO 2 5) }/ ("/.Si02) +40400/ T-6.48 Thephosphorusdistributions betweenhot metal .-i*c~2-""-""""""-"""' . (3) where K2 is the equilibrium constant of Reaction (2) +5/410gp02~logXpo..5 ""-"-"where Xp02 """""' (7) where c((oc'), p(fi') and X are CaO-equivalent coefficients of MnO, P02.5 and Si02, respectively.As a result, it was found that the fractional expression (7) is superior to the algebraic sum expression (6) Effect of (~/oMgO)/("/~MnO) ratio on logypo,, at l 623 K. Since the interaction parameter (eph~') between phosphorus and iron in liquid copper was not reported, the effect of iron content on the activity of phosphorus in liquid copper alloys was neglected in computing the yp02.5value.

The oxidation-reduction equilibrium of manganese in the CaO-MntO-Si02(-MgO-Al203)slag system has been investigated as functions of slag composition, oxygen partial pressure and temperature. where ai = Experirnental apparatus is shown in Fig. 1

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