Combined use of thermal and surface analyses. Study of the smelting process of iron ores from Monte Ferru (Sardinia)

In order to attempt the location of the iron ore sources exploited at Tharros (Sardinia) during the Phoenician-Punic period and to elucidate some chemical aspects of the iron ore smelting process, the iron ore outcrops of Monte Ferru located near to this archaeological site, have been first sampled and then, differential thermal analysis (DTA) and thermogravimetry (TG) have been used for simulating and studying the iron ore smelting process under a carbon monoxide atmosphere. Furthermore, in order to obtain a qualitative identification of minerals present in the iron bearing rocks and for obtaining some thermochemical data, the smelting process has been carried out also under air and Ar-5% H-2 atmospheres. The microchemical aspects involved during the smelting process of the iron ore to crude iron, the formation and the chemistry of new no metallic phases that results from the smelting, i.e. the slags, and the final product of the pyrometallurgical process have been identified via small area X-ray photoelectron spectroscopy (SA-XPS), X-ray induced Auger electron spectroscopy (XAES) and scanning electron microscopy + energy dispersive spectroscopy (SEM + EDS). These results are compared with those obtained from the characterisation of the smelting slags found during the excavation of the archaeological site of Tharros and a relationship is found.