Phase transformations and chemical compositions in different processing products of Pyritum Preparata / 中草药

ABSTRACT

Objective To study the phase transformations and chemical composition changes of Pyritum Preparata (PP) influenced by different processing. Methods To analyse the changes of microstructure, morphology, mineral phase, and chemical compositions in different PP by ore microscope, electron probe microanalyzer technique. Results Greater changes have taken place in chemical compositions of PP after calcination pyrite (FeS_2) changed into pyrrhotite (Fe_(1-x)S), even changed into magnetite (Fe_3O_4); and chalcopyrite generated mutation to be low-copper chalcopyrite, the contents of Cu reduced, the rate of Cu/Fe changed. At the same time, in the pyrrhotite around the mutative chalcopyrite, the contents of Cu increased. That is to say, the Cu got into pyrrhotite and generated solid-solution with high dispersion, and then ore became loose and porous. In the hard-burned spot of calcined quenched samples by vinegar, the contents of Pb and S are far lower than non-burned spot, the minimum estimate of Pb is less than 1/10 of crude ore. Conclusion There is a co-relativity between phase transformations and dissolution of chemical compositions before and after calcining PP.