Manganese vapor pressure, high temperature

Because of the relative instabiUty of FeO, the reduction to metallic Fe occurs at a much lower temperature and appreciable CO2 is present in the product gas. The high temperature required for the reaction of MnO and C results in the formation of essentially pure CO the partial pressures of CO2 and Mn are <0.1 kPa (1 X 10 atm). The product of this reaction is manganese carbide (7 3) [12076-37-8J, Mn C, containing 8.56% carbon. Assuming immiscibility of the metal and carbide, Mn should be obtainable by the reaction of MnO and Mn C at 1607°C. However, at this temperature and activity of Mn, the partial pressure of Mn vapor is approximately 10 kPa (0.1 atm) which would lead to large manganese losses. 

Calcium and particularly magnesium show excessive vapor pressure at steelmaking temperatures. Table I, but this alloyability problem has been somewhat alleviated bj - submerging the introduction of the calcium alloy under 3 meters of liquid steel (31) However, independently of vapor pressure, it is the low solubility of calcium in liquid iron which limits the effective substitution of >feiS by CaS to extremely low sulfur levels, particiilarly when the manganese content is high, 2% for example (32). 

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