Considerations on Copper Smelting from Fahlores and the Metallurgy of Cu-As Bronzes

Abstract The copper production in the Alps began three thousand years BC, usually near ore deposits Austria and Switzerland. For smelting, sulphidic ores like chalcopyrite fahlores were used. Copper produced from was widely used resulting As Sb contents metallic copper. Such alloys generally referred to as arsenical bronzes. However, ancient bronze objects, a wide range of arsenic content observed. One question relates how much is transferred into alloy during smelting. By thermodynamic equilibrium calculations, roasting smelting processes are simulated show that reacts already gaseous compounds before Cu 2 S attacked formed. In case liquid, O 3 formed quickly finally enriched slag. These results have been confirmed by investigation an ingot containing 4 wt. % 2.5 well smaller quantities Sb, Ni, Fe, Ag. main phases apart As, S, oxide. slag sample, inclusion characterized chalcopyrite, FeO, oxide This result accordance with calculations where obtained. Another interesting point loss bronzes remelting. Thermodynamic reveal very stable remelting no evaporation Moreover, oxidation Cu-As, formation favoured not As. Consequently melting Cu-As for casting, at first enrichment melt casted object, respectively. effects superimposed and, if recycled used, starting concentration unknown.