Journal of Mining and Metallurgy, Section B: Metallurgy 2015 Volume 51, Issue 1, Pages: 41-48
https://doi.org/10.2298/JMMB130320004J
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Microstructure characterisation of freeze linings formed in a copper slag cleaning slag
Jansson J. (School of Chemical Technology, Department of Materials Science and Engineering, Aalto University, Espoo, Finland)
Taskinen P. (School of Chemical Technology, Department of Materials Science and Engineering, Aalto University, Espoo, Finland)
Kaskiala M. (School of Chemical Technology, Department of Materials Science and Engineering, Aalto University, Espoo, Finland)
The initial growth rate of freeze linings on water-cooled elements submerged
in molten iron silicate slag is fast. The freeze lining microstructure
forming on water cooled steel surface in a high-silica, slag cleaning furnace
slag of a direct-to-blister copper smelter is mostly glassy or amorphous. It
contains 5-30 μm magnetite crystals, very small and larger copper droplets as
well as small magnetite and silicate nuclei embedded in the glassy
silica-rich matrix. Chemically the formed freeze linings are more silica-rich
than the slag from which they were generated. Magnetite (spinel) is the
primary phase of the solidifying SCF slag but it does not form a continuous
network through the freeze lining. Its strength is given by the intergranular
silica-rich phase which initially is glassy or microcrystalline. Due to only
partial slag reduction in the SCF process, large magnetite crystals are
present in the freeze lining and seem to interact physically with copper
droplets.
Keywords: copper smelting, slag, cooling element, freeze lining