Chemistry Of Inclusions by Size in Three Primary Copper Anodes

Three copper anodes from different commercial electrorefineries were characterized to measure inclusion chemistry, size (diameter), and morphology. An automated scanning electron microscope (SEM) paired with energy-dispersive X-ray spectroscopy (EDS) was used to examine hundreds of inclusions near the mold and set sides of each anode. The investigation revealed that in the two anodes with less impurities (99.65% Cu and 99.75% Cu), many of the inclusions were Cu2O with an average diameter of 2 microns. The greater impurity anode (99.05% Cu, 4076 ppm Pb, 1939 ppm As, 635 ppm Bi) contained significant numbers of complex oxide inclusions, averaging 4.6 microns in diameter. In this anode the weight percents of Bi and Pb increased with increasing inclusion size, and over 50% of the contained Pb in the inclusions were found in inclusions greater than 6.5 microns. Due to EDS peak overlap, electron microprobe with wavelength dispersive spectroscopy was used to supplement the SEM-EDS measurements. In the high impurity anode, the complex oxide inclusions were enriched in Cu near their cores, while As and O contents were greater near their surfaces (shell). The inclusions contained no measurable S. No differences were observed in Bi and Pb inclusion content when comparing the mold and set/air sides