Gas saturation of the matte-slag melt in the Ausmelt® TSL furnace and the special aspects of natural gas combustion therein

Summarizing the operating experience of JSC Karabashcopper in the autogenous Ausmelt unit equipped with a TSL enables the development of new vertical blast processes, as well as the refinement and advancement of smelting technologies. Theoretical analysis and evaluation of the physical and chemi-cal processes occurring in the slag-matte melt in an industrial furnace allows to develop and accumulate the knowledge base for this technology. A two-phase model was generated; the bath state and its saturation with gas bubbles was analysed. Evaluating the boundary conditions for gas saturation and the diameter of gas inclusions enables monitoring the bath state and preventing melt foaming during operation, ensuring maximum equipment performance. The composition of the oxygen-air mixture/natural gas mixture significantly impacts the performance of the tuyere when injecting blast into the melt. JSC Karabashcopper operates in a mode that maximizes natural gas usage to enable processing low-sulphur feedstock. Data analysis over many years has shown that the process operates under boundary conditions for natural gas ignition at the tuyere tip, which creates the preconditions for its failure. The presented methodology for assessing natural gas combustion conditions in the melt enables the in-formed selection of the best process parameters for a specific natural gas composition and actual blast pa-rameters with specified swirl parameters.