To improve the fluidity of slag and to smoothly recover valuable metal by treating copper residues contg. valuable metal and industrial waste contg. metal and, while the generated slag is reduced, feeding a solvent contg. at least one kind among CaO, SiO2 and Fe therein.
Preferably, the flowing length of slag after the addition of a solvent is ≥18 cm, where stainless strip steel with a V type groove of 5 cm width inclined in the longitudinal direction at 7.5° inclined angle is heated at 200 to 250°C in such a manner that the groove face is orientated toward the upper direction, the slag of 150 g is flowed down from the upper direction of 10 cm to the groove face, and, by the length in which it has flowed off the groove face, its fluidity is measured. Moreover, the slag is composed of, by weight, 5 to 35% Cu2O, 5 to 17% FeO, 1 to 15% ZnO, 20 to 45% SiO2, 25 to 45% CaO and 10 to 20% Al2O3. The slag G is poured into an electric type holding furnace 31, and a graphite electrode is inserted into the slag bath, which is energized and melted. For optimizing the viscosity of the slag G, jointly with reduction, a solvent is continuously poured, and refining is executed. Black copper I having about 70 to 90% copper grade can be obtd.
KAWASAKI YASUTO
ASAI KAZUHIRO
KAWAI SHIRO
AZUMA MASARU
OKURA TAKAHIKO
