<Original Papers>On the Re-treatment of Zinciferous Residues from Japanese Smelters

The question of zinciferous residues was examined and discussed from the viewpoint that the more complete utilization of zinc constitutes a key to the rehabilitation of Japanese sulfide mineral industries as a whole. Leached residue of the Annaka Electrolytic Zinc Plant was taken as an example and laboratory reduction experiments were carried out to ascertain the behaviours of various constituents and to establish the best condition for complete recovery of zinc when it was re-treated. The softening points of the slag-forming constituents were found to play by far the most important part, so that a reroasting and sintering test of the sample brought forth a much improved recovery of zinc due to absence of iron sulfide. A new form of zinc lost in the final residue of re-treatment was found which was possibly due to metallic zinc enclosed in pasty globules of slag-forming constituents