LAUSR

Effects of cooling conditions on phase and microstructure in copper slag were studied. X-ray analysis of water-quenched slag shows noncrystalline, FeO-rich silicate phase, spherical copper loss particles, and a trace of crystalline phase. The slowly cooled slag in a furnace showed mainly fayalite and magnetite phases and SiO2-rich (>65 mol%) alumino-silicate matrix phase with copper loss particles. The crystallized slag indicated less than one-tenth amount of the elution amounts of Pb and As in 1 mol/L HCl aqueous solution at room temperature, compared with the water-quenched slag. The formation of fayalite and magnetite phases resulted in the change of residual noncrystalline matrix from FeO-rich silicate to SiO2-rich alumino-silicate compositions. Good stability against Pb and As dissolution in the HCl aqueous solution and SEM–EDS analysis for the crystallized copper slag suggested that Pb and As elements were present in the SiO2-rich alumino-silicate matrix and embedded spherical particles of copper losses.