Cullet sorting by differential thermal characteristics
First Claim
1. Method for separating a stream of mixed particulates of at least two distinct materials having at least one of different thermal, dielectric strength and loss tangent characteristics, comprising:
- providing a conveying means having a heating path followed by a detecting path;
spreading a heating layer of mixed particulates, having a heating layer thickness, along the heating path;
heating the heating layer to an exit temperature with an electromagnetic induction heater disposed along the heating path, the electromagnetic induction heater being operable to apply an electromagnetic field to heat the heating layer;
spreading the heating layer along the detecting path thereby forming a detecting layer having a detecting layer thickness, the heating layer thickness being larger than the detecting layer thickness;
detecting and signaling a difference in temperature between the two distinct materials in the detecting layer using a temperature sensor operable to detect and signal the difference in temperature between the two distinct materials occurring as a result of said different thermal characteristics;
diverting a portion of the detecting layer as a function of the difference in temperature, whereby the two materials are separated using at least one controllable diverting mechanism responsive to a signal of the temperature sensor for diverting a portion of the detecting layer.
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Accused Products
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. The thermal image data is analyzed for temperature differences, particularly for temperature differences from an average temperature computed for discrete lateral lanes. A downstream diverter mechanism is triggered to divert incremental portions of the material stream found to contain temperature differences, thereby removing the contaminants.
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Citations
24 Claims
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1. Method for separating a stream of mixed particulates of at least two distinct materials having at least one of different thermal, dielectric strength and loss tangent characteristics, comprising:
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providing a conveying means having a heating path followed by a detecting path; spreading a heating layer of mixed particulates, having a heating layer thickness, along the heating path; heating the heating layer to an exit temperature with an electromagnetic induction heater disposed along the heating path, the electromagnetic induction heater being operable to apply an electromagnetic field to heat the heating layer; spreading the heating layer along the detecting path thereby forming a detecting layer having a detecting layer thickness, the heating layer thickness being larger than the detecting layer thickness; detecting and signaling a difference in temperature between the two distinct materials in the detecting layer using a temperature sensor operable to detect and signal the difference in temperature between the two distinct materials occurring as a result of said different thermal characteristics; diverting a portion of the detecting layer as a function of the difference in temperature, whereby the two materials are separated using at least one controllable diverting mechanism responsive to a signal of the temperature sensor for diverting a portion of the detecting layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for separating a stream of mixed particulates of at least two distinct materials having at least one of different thermal, dielectric strength and loss tangent characteristics, comprising:
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means operable to move the stream of mixed particulates along a heating path and a detecting path; means for spreading a heating layer of mixed particulates, having a heating layer thickness, along the heating path; an electromagnetic induction heater disposed along the heating path and operable to apply an electromagnetic field to heat the heating layer to an exit temperature; means for spreading the heating layer onto the detecting path thereby forming a detecting layer having a detecting layer thickness, the heating layer thickness being larger than the detecting layer thickness; at least one temperature sensor operable to detect a temperature of particulates in the detecting layer at least at one discrete point along the detecting path, the temperature sensor being operable to detect and signal a difference in temperature between the two distinct materials occurring as a result of said different thermal characteristics; and
,at least one diverting mechanism controllable responsive to a signal of the temperature sensor for diverting a portion of the detecting layer as a function of the difference in temperature, whereby the two materials are separated. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification