Power, fluid flow and temperature distributions in electric smelting of nickel matte

摘要

A voltage probe was constructed to makesimultaneous, multiple voltage measurements in Falconbridge's36 MVA furnace for smelting nickel calcine. It was evident thatthere was significant voltage drop at the electrode surface, 100to 120 volts for an applied potential of 180 to 230 volts. Thisdrop at the surface was attributed to arcing through the carbonmonoxide generated by electrode erosion. Thus, heat wasreleased in the immediate vicinity of the electrode due to arcing,as well as in the bulk of the slag by Joule heating. A three-dimensional mathematical model was developed to simulate thedistributions of voltage, heat release, temperature and velocity inthe slag and matte. Incorporation of the arcing phenomenon intothe model permitted accurate calculation of the current, powerand temperature distributions in the slag and matte. The slagwas found to be thermally homogenized due to the evolved gas,and to a lesser extent by natural convection. In contrast, thematte was thermally stratified; this finding was attributed topoor momentum transfer across the slag/matte interface. Theimplications of these findings for stable furnace operation are discussed.