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The dissolution of Cu2O in fayalite is one of the chief processes that cause copper loss in metallurgical processes. In this paper, the interaction between fayalite and Cu2O is systematically studied to verify the main mechanism of copper loss as well as the variation in the fayalite microstructure. The results indicate the simultaneous occurrence of melting and dissolution of copper in fayalite. The redox reaction of Cu + + Fe 2 + = Cu + Fe 3 + occurs in the melt phase, resulting in the generation of metallic copper and amorphous iron. The copper dissolution impacts the fayalite microscopically. With the increase of Cu2O, the obvious phase separation is seen in the fayalite melt, and large metal particles are dispersed in the melt. In addition, the dissolution mechanism of copper and the change in the fayalite microstructure are analyzed by x-ray photoelectron spectroscopy and Raman spectroscopy. The results show that amorphous iron trapping Cu(I) and the formation of fayalite-combined copper are the most probable mechanisms for copper dissolution and the fayalite microstructure changes. These findings provide theoretical support for the secondary extraction of copper resources from copper slag. [ABSTRACT FROM AUTHOR]

The sintering behaviors among SiO2, FeS and Fe3O4 were detected to reveal the formation mechanism of Fe2SiO4. The results indicated that the formation mechanism is divided into five steps: (1) migration of O2− induced by S2− under a reducing atmosphere; (2) formation of Fe3O4−β; (3) migration of Fe(II) into a ferrite cluster structure to gain oxygen and form Fe3−xO4; (4) Fe(II) invaded the silicon atomic position and released Si(IV); and (5) formation of the stable structure of Fe2SiO4 through chemical diffusion between cations of Fe(II) and Si(IV). These findings can provide theoretical support for controlling the process of the recovery of valuable metals in copper slag through the combined roasting modification-magnetic separation process. [ABSTRACT FROM AUTHOR]