Authors: C. Jiang, Hatch Beijing, Roumeliotis and R. Harris, McGill
5th International Copper Conference, Pyrometallurgy of Copper, Santiago, Chile, November 2003
Abstract
Experiments were performed to determine the potential of vacuum roasting of copper concentrates to eliminate the imputities, As, Sb, Bi, Pb, and Zn prior to their entry into the copper smelting circuit. One hundred gram samples of three copper concentrates of different chemical, mineralogical composition and impurity content were roasted at temperatures between 400⁰C and 900⁰C under a vacuum if 80 Pa for a period of 30 to 90 minutes in a stainless steel cylindrical retort that was air-colled on one end. It was found that almost complete removal of As, Sb, Pb, and up to 60% Zn and 90% Bi elimination from the concetrates was achieve after 60 minutes of vacumm roasting at 900⁰C. Less elimination was observes at lowe temperatures and shorter times and the rate and ultimate level of elimination was seen to vary with the mineralogical composition but in no obvious pattern. Scanning electron microscopy performed on samples of the copper concetrates prior to roasting revealed distince sulfide particles of Pb and Zn but not of As, Sb nor Bi. X-ray diffraction analyses also failed to detect the presence of silfides or either of As, Sb, or Bi. Examination of the retort interior in the vicinity of the air-cooled region at the end of reasting trials showed segregated condensation of the volatized metallic components and the sulfer; this observation suggests that the separare, stage-wise crecovery of separation of these metals may be possible.
