Secondary building material useful in road and concrete constructions - produced from rubble and old waste incineration slag

摘要

A method of producing secondary building materials from old waste incineration slags involves mixing of the slags with rubble, magnetic separation of large iron scrap, dry classification at 70 mm sieve size, treatment of the below 70 mm size fraction by further magnetic separation, dry classification at 32 mm with return of oversize material to a slowly operating impact crusher and then to the initial magnetic separation, and delivery of the below 32 mm size dry material onto a 2 mm sieve. The novelty comprises the subsequent steps of (a) spraying water at 5-8 bars from high pressure nozzles onto the sieve; (b) supplying a floating collector material to the below 2 mm size sieved material and separating the material into two particle classes in a two-stage upward flow classifier; and (c) subjecting the 2-32 mm size material to simultaneous attrition and high pressure water sprays in a twin shaft wet attritor. Also claimed is a secondary building material produced by the above method.