Some bismuth-rich alloys

FIG. 29.20. Structures of some bismuth-rich alloys (a) coordination polyhedron around transition metal atom, (b)-(d) packing of these coordination polyhedra in [Pg.1049]

The washed slime is dried and melted to produce slag and metal. The slag is usually purified by selective reduction and smelted to produce antimonial lead. The metal is treated ia the molten state by selective oxidation for the removal of arsenic, antimony, and some of the lead. It is then transferred to a cupel furnace, where the oxidation is continued until only the silver—gold alloy (dorn) remains. The bismuth-rich cupel slags are cmshed, mixed with a small amount of sulfur, and reduced with carbon to a copper matte and impure bismuth metal the latter is transferred to the bismuth refining plant. 

The bismuth-rich slags from the converter operation and from dord cupellation can be reduced in a short rotary furnace with coal and some sulfur addition to give a bismuth-lead alloy and a copper matte. The bismuth-lead alloy can be refined by a similar sequence as used for the thermal refining of lead, as follows ... 

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