Raw materials for refining valuable metals and raw material recovery methods for refining valuable metals

摘要

PROBLEM TO BE SOLVED: To recover valuable metals contained in waste matter such as city waste incineration ash and sludge at a low cost.SOLUTION: A raw material D5 for refining valuable metals is obtained as a solid by extracting a part of the combustion gas from a kiln exhaust gas flow passage which is extended from the kiln tail of a cement kiln 5 to a lowermost-stage cyclone, while cooling the gas and subjecting the extracted gas G1 to solid-gas separation and contains at least one of gold, silver and bismuth. The raw material for refining valuable metals can be obtained at no additional cost in an exhaust gas treatment process of the cement kiln. The raw material for refining valuable metals can be obtained as the solid by separating the extracted gas into coarse powder D1 and a gas G2 containing fine powder D2, the 10 m sieve-passed content of which is 80 mass% or higher, and subjecting the gas containing fine powder to solid-gas separation. Since the raw material for refining valuable metals is obtained from such fine powder that the concentration of calcium or silicon is low and those of the valuable metals are high, the raw material for refining valuable metals, the valuable metal concentration of which is several times higher than that of a natural ore, can be obtained.