Claims
- 1. A non-magnetic process for the separation of non-ferrous metallic particles from a solid waste mixture of non--metallic particles, ferrous metallic particles and non-ferrous metallic particles, comprising the steps of:
- (a) conducting a solid waste mixture of non-metallic particles, ferrous metallic particles, and non-ferrous metallic particles in a feed stream through a concentration zone,
- (b) electronically detecting said non-ferrous metallic particles in said concentration zone by passing all said particles in the vicinity of a detector coil connected in a phase detector circuit, said circuit producing a frequency phase error signal comparable to a decrease in the inductance of said detector coil responsive only to the proximity of said non-ferrous metallic particles,
- (c) removing said non-ferrous metallic particles from said ferrous metallic particles and said non-metallic particles in said feed stream in response to said frequency phase error signal.
- 2. The invention according to claim 1 further comprising the step of high-pass filtering said error signal so that said error signal is free of low frequencies generated by thermal drift of said phase detector circuit.
- 3. The process according to claim 1 in which said removing step comprises producing air pulses to project said non-ferrous metallic particles detected in said concentration zone in response to said error signal away from the other particles in said solid waste mixture in said feed stream.
- 4. The process according to claim 3 further comprising the step of delaying the producing of said air pulses after the production of said frequency phase error signal until the detected non-ferrous metallic particles are in the path of said air pulses.
- 5. The process according to claim 4 further comprising the step of high-pass filtering said error signal generated by said phase detector circuit.
- 6. The process according to claim 1 in which said phase detector circuit is a closed loop circuit including said detector coil and a phase lock loop.
- 7. The process according to claim 1 in which said removing step comprises projecting said non-ferrous metallic particles detected in said concentration zone in response to said error signal away from said feed stream of said solid waste mixture.
BACKGROUND OF THE INVENTION
This is a continuation-in-part of Ser. No. 397,559, now U.S. Pat. No. 4,541,530, filed July 12, 1982.
US Referenced Citations (9)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0045869 |
Apr 1979 |
JPX |
197709 |
Apr 1975 |
SUX |
639684 |
Dec 1978 |
SUX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
397559 |
Jul 1982 |
|