TRANSPORT PHENOMENA IN ELECTRIC SMELTING OF NICKEL MATTE - PART II - MATHEMATICAL-MODELING

A three-dimensional mathematical model was developed to simulate the d istributions of electrical potential, heat release, temperature, and v elocity in the slag and matte in a six-in-line 36 MVA capacity furnace for smelting nickel calcine. From Part I of this series, it was found that there was a substantial electrical potential drop at the electro de surface, likely due to arcing through evolved carbon monoxide. The incorporation of this phenomenon into the model permitted accurate cal culation of the current, power, and temperature distributions in the s lag and matte. The slag was found to be thermally homogenized due to t he evolved gas, and to a lesser extent by natural convection. In contr ast, the matte was thermally stratified; this finding was attributed t o poor momentum transfer across the slag/matte interface. Ninety perce nt of the electrical energy was used in smelting reactions in the calc ine; to simulate the heat transfer from the slag to the calcine, a hea t transfer coefficient was deduced from plant data. The implications o f these findings for stable furnace operation are discussed.