Commercial production of copper by continuous casting in a wheel-and-band machine, with suitable modifications to induce high undercooling, is considered. Impurities control to a large extent the microstructure and mechanical properties of the ingot. Suitable solute additives in the molten alloy to achieve constitutional supercooling during solidification have been analyzed, with particular emphasis on the presence of lead. Experimental information on the Cu-O-Pb phase diagram has been revised and modeling of the microstructure evolution as a function of several casting parameters is being presented.