An Update to the Fluxing Practice of the Rio Tinto Kennecott Copper Flash Converter

The flash converter at Rio Tinto Kennecott in Salt Lake City, Utah, has been operating with a calcium ferrite (Ca₂Fe₂O₅) slag since its commissioning in 1995. Major components of the slag system are Ca, Fe, and Cu oxides, but the minor components silica and arsenic significantly affect the slag and furnace operation. Lime (CaO) fluxing practice originally aimed to flux only iron in the furnace feed. Issues controlling solid buildup in the converting furnace eventually drove a better understanding of the impact of minor components on the slag system. An empirical equation was developed between magnetic susceptibility of the slag and its major and minor components. This understanding allowed a controlled variable (lime flux to the furnace) to vary with uncontrolled variables (major and minor components in slag) aiming to maintain a constant magnetic susceptibility of the slag, which is desirable for maintaining a controlled amount of accretion in the furnace, improving campaign life and operability. New thermodynamic understanding provided by collaboration with researchers at the University of Queensland facilitated a recent modification of the fluxing strategy, based on thermodynamic fundamentals, to better control furnace accretion.