Slag system equilibria

Since the mole fraction of K2O can be defined at any stage of an experiment, it is>possible to convert K-partial pressures to K2O activity coefficients using equation [6]. By varying the amount of K2O present in the slag during a vaporization run, we were able to follow the dependence of the K2O "apparent" thermodynamic activity on temperature and composition. The term "apparent is used to emphasize that the slag system may not always be in a state of complete thermodynamic equilibrium. Typical data. 

The silicate slag systems are involved in most pyro-metallurgical processes which result in the formation of a number of ferrous and non-ferrous metals (Cu, Ag, Zn, Cd Sn, Pb, Sb, Bi). These systems are oxide- and sulfide-oxide melts, and, therefore, the processes of their interaction with raw materials are dependent on the melt properties (oxidation ability, solubility of metals), and on their oxoacidic properties. Any metallurgical slag contains MgO, CaO, FeO and Si02 as one of main components. The oxidation ability of the slags increases with a rise of their basicity (increase of equilibrium O2-concentration), caused by the following electrochemical process ... 

The equilibrium thickness increases as the of the refractory-slag system increases, i.e., as more slag-resistant refractories are used. This usually means the use of higher-purity refractories, namely higher alumina content or higher MgO purity. 

In a steel refining process, molten steel eventually comes into equilibrium with slag and gas phases coexisting in the furnace. The furnace can be considered as a closed system. The species identified in each phase are given in the following ... 

For slags exhibiting a transition in behavior, the transition temperature could usually be associated with a ternary eutectic temperature in the phase equilibrium diagram for the most closely related ternary system. 

Calculate the value of the equilibrium constant and standard free energy change for the above reaction at 1655°C 1928 K), assuming that the slag and Fe-Mn system behave ideally at that temperature. Neglect the effect of other metalloids present in the steel. 

Lurgi (BGL) system [20] is moved to the fluid-bed domain C as a result of combining slagging and moving-bed conditions. Because the moving-bed domain D is completely below 800 °C, equilibrium is not possible. To emphasize this fact, the domain is indicated by dashed lines. 

Corrosion reactions should be viewed as attempts by the system to achieve compatibility by progressing toward equilibrium. Refractories are rarely at chemical equilibrium on a microscopic scale since they are typically made from mixtures of different minerals. However, at the immediate corrosion interface between the refractory and the slag, the localized volume elements may be at or close to chemical equilibrium. 

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