QUANTITATIVE-DETERMINATION OF PHASES PRESENT IN OXIDIZED CHALCOCITE

A sample of chalcocite (Cu2S) of particle size 45-75 mu m was heated i n air at 10 degrees C min(-1) in a simultaneous TG-DTA apparatus. The phase compositions of the products at various temperatures were quanti tatively determined by X-ray diffraction (XRD), Fourier transform infr ared (FTIR) spectroscopy, and wet chemical analyses. Copper(II) sulfat e, of amount 1.7% by mass, was observed at 435 degrees C and increased rapidly in concentration to 56% at 570 degrees C. From 570-670 degree s C, there was a rapid decrease in CuSO4 content to 9.8% as the phase converted to CuSO4 . CuO, with the CuSO4 not being detected at 775 deg rees C. From 435-570 degrees C, Cu2O formed, but at a rather slower ra te, reaching 47% at 570 degrees C. The Cu2O level then decreased to 38 % over the range 570-670 degrees C. CuSO4 . CuO was first detected at 570 degrees C by FTIR, although it was not detected by XRD at this tem perature. The content of this species reached 41% at 670 degrees C, de creased to 24% at 775 degrees C, and tvas not detected at 840 degrees C. CuO first appeared at 670 degrees C and rose steadily in concentrat ion until at 840 degrees C it was the only compound present.