Speciation of copper in plasma-melted slag

Abstract

Speciation of copper in the laboratory waste incineration ashes and plasma-melted slag has been studied by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXFAS) spectroscopies. The component-fitted XANES spectra show that main copper species in the bottom and fly ashes are CuO (9–45%), Cu(OH) 2 (25–40%) and nanosize CuO (30–35%). During the plasma melting process at 1773 K, about 97% of Cu 2S in the slag is observed possibly due to sulfurization and self-reduction of CuO at high temperatures. By EXAFS, we also found that copper in the bottom and fly ashes possessed Cu O bond distances of 1.97 and 1.99 Å with coordination numbers (CNs) of 2.1 and 2.3, respectively. In the slag, the bond distance of Cu–S is 2.3 Å with a CN of 3.8.