Abstract: Glass cullet such as recycled municipal waste is processed to substantially eliminate contaminants including light weight paper and polymer, ferrous and nonferrous metal and also ceramics, pyroceramics, tempered glass, stones and assorted silicates that have properties approximating those of glass. In a series of washing and sorting steps, different mechanical, chemical, electromagnetic, and thermal processes cause distinct materials in the cutlet to react differently, whereupon the contaminants are selectively removed and the glass is processed on. The cullet is crushed; ferrous and nonferrous metals are detected and diverted, a screening station sizes cullet particles and routes larger sizes back for additional crushing. An air blower entrains and removes light fractions and dust. A wash station entrains and removes dirt and soluble material. In a flow of sized particles, further metal and ceramic (non-glass silica) detection devices divert portions of the flow sensed to contain non-glass materials.

Abstract: A stream of mixed particulates of two or more materials having different induction heating characteristics (i.e., distinct thermal, dielectric strength and/or loss tangent characteristics), such as recycled glass cullet including fragments of glass mixed with fragments of glass-like contaminants such as ceramics, pyroceramics, tempered glass or the like, is sorted using the differing characteristics of the glass and contaminants to cause detectable differences in temperature. A thick heating layer many particles deep is formed on a conveyor path for heating the stream in a compact mass for uniform heating. An electromagnetic induction heater applies microwave energy between 0.915 and 2.45 GHz for heating the mass, which is then spread into a thin detecting layer, for example one particle deep, on a further conveyor. The detecting layer is digitally imaged using a thermal camera.