Production of clean glass particles from post-consumer waste

Abstract

Clean glass particles are produced from post-consumer mixed glass and like waste streams by a series of pulverizing, size- and material-based separation, ozonation, drying, sizing, and paper fluff removal steps.

What is claimed is: 
     
       1. A system for producing a stream of clean, sterilized, and sized glass particles from post consumer and like waste streams, comprising:
 a pulverizing system, for breaking the glass into relatively small fragments, while not breaking other less-frangible materials in the waste stream; 
 a magnet for removing ferrous metals from the waste stream; 
 a trommel separator, for separating the glass fragments by size; 
 an air classification system for removing paper and other light materials from at least one of the glass streams exiting the trommel separator; 
 an ozone sterilization system, in which the glass particles are exposed to ozone to kill bacteria; 
 a fluidized bed dryer, for drying residual moisture from the particles with a stream of hot air at a temperature sufficiently low as to avoid burning or oxidation of non-glass particles; 
 a first screening system, for performing size-based separation of the glass particles; 
 a gyratory screening device for causing fine fibers of paper and plastic mixed with the glass particles to agglomerate; and 
 a vibratory conveyor comprising a first pan for receiving a layer of glass particles from the gyratory screening device, the pan being driven in a vibratory manner causing agglomerated fine paper and plastic fibers to rise to the surface of the layer of glass in the pan, and a screen section having a screen of mesh sized such that the glass particles fall through the screen, while the agglomerated paper and plastic fibers remain on the screen for subsequent removal. 
 
     
     
       2. The system of  claim 1 , further comprising diverters to allow the flow of glass particles to be diverted to containment devices for storing the glass particles for subsequent use. 
     
     
       3. The system of  claim 1 , further comprising a re-grind loop including said first screening system and a secondary pulverizer to further reduce the glass without creating sharp edges or breaking down plastic and paper. 
     
     
       4. The system of  claim 1 , wherein said trommel separator comprises two cylindrical barrel screens of made of screens of different mesh size, arranged in series, with the smaller-mesh screen barrel in the upstream position, so that smaller glass particles are removed first by falling through said smaller-mesh screen, and larger glass particles and large non-glass particles are removed second by falling through a larger-mesh screen, and such that items larger than the mesh size of the second screen exit the second barrel screen. 
     
     
       5. The system of  claim 4 , where a fan blows air through a stream of larger glass particles and larger non-glass particles falling from said larger-mesh screen, such that lighter materials such as paper scraps are removed from the falling stream of glass. 
     
     
       6. The system of  claim 1 , further comprising an eddy-current separator for removing metallic material from the waste stream. 
     
     
       7. The system of  claim 1 , wherein said ozone sterilization system comprises an ozone generator and an enclosed vibratory feeder, such that glass particles in the vibratory feeder are constantly agitated, so that their surfaces are efficiently exposed to the ozone in the chamber. 
     
     
       8. The system of  claim 1 , wherein said vibratory conveyor comprises a second pan located under said first pan, so that the glass particles falling through said screen fall onto said pan for collection. 
     
     
       9. The system of  claim 8 , wherein said agglomerated paper and plastic fibers also fall onto said second pan for collection. 
     
     
       10. A method for producing a stream of clean, sterilized, and sized glass particles from post consumer and like waste streams, comprising the steps of:
 pulverizing the glass into relatively small fragments, while not breaking other materials in the waste stream; 
 employing a magnet to removing remove ferrous metals from the waste stream; 
 employing a trommel separator to separate the glass fragments by size from other less-frangible materials in the waste stream; 
 blowing a stream of air across at least one of the glass streams exiting the trommel separator for removing paper and other light materials there from; 
 exposing the glass particles to ozone to kill bacteria; 
 employing a fluidized bed dryer, to dry residual moisture from the particles with a stream of hot air at a temperature sufficiently low as to avoid burning or oxidation of non-glass particles; 
 employing a first screening system to perform size-based separation of the glass particles; 
 agitating the particles in a gyratory screening device to cause fine fibers of paper and plastic mixed with the glass particles to agglomerate; and 
 providing a vibratory conveyor comprising a first pan to receive a layer of glass particles from the gyratory screening device, and driving the pan in a vibratory manner causing agglomerated fine paper and plastic fibers to rise to the surface of the layer of glass in the pan, and passing the glass particles over a screen section having a screen of mesh sized such that the glass particles fall through the screen, while the agglomerated paper and plastic fibers remain on the screen for subsequent removal. 
 
     
     
       11. The method of  claim 10 , further comprising the step of providing a re-grind loop including said first screening system and a secondary pulverizer to further reduce the glass without creating sharp edges or breaking down plastics and paper. 
     
     
       12. The method of  claim 10 , wherein said trommel separator comprises two cylindrical barrel screens of made of screens of different mesh size, arranged in series, with the smaller-mesh screen barrel in the upstream position, so that smaller glass particles are removed first by falling through said smaller-mesh screen, and larger glass particles and large non-glass particles are removed second by falling through a larger-mesh screen, and such that items larger than the mesh size of the second screen exit the second barrel screen. 
     
     
       13. The method of  claim 12 , where a fan blows air through a stream of larger glass particles and large non-glass particles falling from said larger-mesh screen, such that lighter materials such as paper scraps are removed from the falling stream of glass. 
     
     
       14. The method of  claim 10 , further comprising the step of employing an eddy-current separator for removing metallic material from the waste stream. 
     
     
       15. The method of  claim 10 , wherein said ozone sterilization system comprises an ozone generator and an enclosed vibratory feeder, such that glass particles in the vibratory feeder are constantly agitated, so that their surfaces are efficiently exposed to the ozone in the chamber. 
     
     
       16. The method of  claim 10 , wherein said vibratory conveyor comprises a second pan located under said first pan, so that the glass particles falling through said screen fall onto said pan for collection. 
     
     
       17. The method of  claim 16 , wherein said agglomerated paper and plastic fibers also fall onto said second pan for collection. 
     
     
       18. A system for producing a stream of clean, sterilized, and sized glass particles from post consumer and like waste streams, comprising:
 a pulverizing system, for breaking the glass into relatively small fragments, while not breaking other less-frangible materials in the waste stream;   a size-based separator, for separating the glass fragments by size from the less-frangible materials;   a dryer, for drying residual moisture from the particles with a stream of hot air at a temperature sufficiently low as to avoid burning or oxidation of non-glass particles, but sufficiently high to provide sterilization;   a first screening system, for performing size-based separation of the glass particles into streams of coarser and finer particles;   a gyratory screening device for causing fine fibers of paper and plastic mixed with the finer glass particles to agglomerate; and   a vibratory conveyor comprising a first pan for receiving a layer of glass particles from the gyratory screening device, the pan being driven in a vibratory manner causing agglomerated fine paper and plastic fibers to rise to the surface of the layer of glass in the pan, and a screen section having a screen of mesh sized such that the glass particles fall through the screen, while the agglomerated paper and plastic fibers remain on the screen for subsequent removal.   
     
     
       19. The system of claim 18, further comprising diverters to allow the flow of glass particles to be diverted to containment devices for storing the glass particles for subsequent use. 
     
     
       20. The system of claim 18, further comprising a re-grind loop including said first screening system and a secondary pulverizer to further reduce the glass without creating sharp edges or breaking down plastic and paper. 
     
     
       21. The system of claim 18, wherein said size-based separator is a trommel separator comprising two cylindrical barrel screens of different mesh size, arranged in series, with the smaller-mesh screen barrel in the upstream position, so that smaller glass particles are removed first by falling through said smaller-mesh screen, and larger glass particles and large non-glass particles are removed second by falling through a larger-mesh screen, and such that items larger than the mesh size of the second screen exit the second barrel screen. 
     
     
       22. The system of claim 21, further comprising an air separation device, comprising a fan for blowing air through a stream of larger glass particles and larger non-glass particles falling from said larger-mesh screen, such that lighter materials such as paper scraps are removed from the falling stream of glass. 
     
     
       23. The system of claim 18, further comprising an eddy-current separator for removing metallic material from the waste stream. 
     
     
       24. The system of claim 18, further comprising an ozone sterilization system comprising an ozone generator and an enclosed vibratory feeder, such that glass particles in the vibratory feeder are constantly agitated, so that their surfaces are efficiently exposed to the ozone in the chamber. 
     
     
       25. The system of claim 18, wherein said dryer is a fluidized bed dryer. 
     
     
       26. The system of claim 25, wherein said vibratory conveyor comprises a second pan beneath the first pan, whereby said glass particles fall onto said second pan for collection. 
     
     
       27. The system of claim 18, further comprising a magnetic separator for removing ferrous metals from the waste stream. 
     
     
       28. A method for producing a stream of clean, sterilized, and sized glass particles from post consumer and like waste streams, comprising the steps of:
 pulverizing the glass into relatively small fragments, while not breaking other materials in the waste stream;   employing a size-based separator to separate the glass fragments by size from other less-frangible materials in the waste stream;   drying residual moisture from the particles with a stream of hot air at a temperature sufficiently low as to avoid burning or oxidation of non-glass particles, while hot enough to provide sterilization of the particles;   employing a first screening system to perform size-based separation of the glass particles into streams of coarser and finer particles;   agitating the finer particles in a gyratory screening device to cause fine fibers of paper and plastic mixed with the glass particles to agglomerate; and   providing a vibratory conveyor comprising a first pan to receive a layer of glass particles from the gyratory screening device, and driving the pan in a vibratory manner causing agglomerated fine paper and plastic fibers to rise to the surface of the layer of glass in the pan, and passing the glass particles over a screen section having a screen of mesh sized such that the glass particles fall through the screen, while the agglomerated paper and plastic fibers remain on the screen for subsequent removal.   
     
     
       29. The method of claim 28, further comprising the step of providing a re-grind loop including said first screening system and a secondary pulverizer to further reduce the glass without creating sharp edges or breaking down plastics and paper. 
     
     
       30. The method of claim 28, wherein said size-based separator comprises a trommel separator comprising two cylindrical barrel screens made of screens of different mesh size, arranged in series, with the smaller-mesh screen barrel in the upstream position, so that smaller glass particles are removed first by falling through said smaller-mesh screen, and larger glass particles and large non-glass particles are removed second by falling through a larger-mesh screen, and such that items larger than the mesh size of the second screen exit the second barrel screen. 
     
     
       31. The method of claim 30, further comprising a fan blowing air through a stream of larger glass particles and large non-glass particles falling from said larger-mesh screen, such that lighter materials such as paper scraps are removed from the falling stream of glass. 
     
     
       32. The method of claim 28, further comprising the step of employing an eddy-current separator for removing metallic material from the waste stream. 
     
     
       33. The method of claim 28, further comprising the step of passing said glass particles through an ozone sterilization system comprising an ozone generator and an enclosed vibratory feeder, such that glass particles in the vibratory feeder are constantly agitated, so that their surfaces are efficiently exposed to the ozone in the chamber. 
     
     
       34. The method of claim 28, wherein said vibratory conveyor comprises a second pan located under said first pan, so that the glass particles falling through said screen fall onto said pan for collection. 
     
     
       35. The method of claim 34, wherein said drying step is performed employing a fluidized bed dryer. 
     
     
       36. Apparatus for separating fibers of paper from glass particles in a mixed stream thereof, comprising:
 a gyratory screen device for performing a first density-based separation, comprising a substantially horizontal pan wherein the stream of glass particles and paper fibers are agitated, whereby the paper fibers tend to rise to the top of the stream and agglomerate into paper fluff balls larger in diameter than the glass particles; and   a vibratory screen device for performing a second size-based separation, wherein the stream of glass particles and paper fluff balls are first disposed on a first pan having a first solid surface, and wherein the glass particles and paper fluff balls then migrate under vibratory action of said vibratory screen device to a second mesh surface of said pan of mesh sized to pass the glass particles but not the paper fluff balls, whereby the glass particles fall through the screen and are thereby separated from the paper fluff balls, which remain on the screen for subsequent removal.   
     
     
       37. The apparatus of claim 36, wherein said gyratory screen device comprises a screen of mesh sized to separate the glass particles into streams of coarser and finer particles, wherein the paper fibers tend to be mixed primarily with the finer particles, and wherein the stream of finer particles and paper fluff balls is supplied to said vibratory screen device for separation of the paper fluff balls from the glass particles. 
     
     
       38. The apparatus of claim 36, wherein said vibratory screen device comprises a second pan disposed beneath said first pan and arranged to collect the glass particles falling through the mesh screen surface. 
     
     
       39. The apparatus of claim 36, wherein said first pan of said vibratory screen device is divided longitudinally by a divider into two or more parallel aisles, wherein the mesh sizes of said screen sections of said pan differ in said aisles, and where differently-sized streams of glass particles with paper admixed therewith are supplied to said two or more aisles from said gyratory screen device. 
     
     
       40. A method for separating fibers of paper from glass particles in a mixed stream thereof, comprising the steps of:
 employing a gyratory screen device for performing a first density-based separation, wherein the stream of glass particles and paper fibers are agitated on the surface of a generally horizontal pan, whereby the paper fibers tend to rise to the top of the stream and agglomerate into paper fluff balls larger in diameter than the glass particles; and   separating the paper fluff balls from the glass particles.   
     
     
       41. The method of claim 40, wherein said step of separating the paper fluff balls from the glass particles is performed employing a vibratory screen device for performing a second size-based separation, wherein the stream of glass particles and paper fluff balls are first disposed on a first pan having a first solid surface, and wherein the glass particles and paper fluff balls then migrate under vibratory action of said vibratory screen device to a second mesh surface of said pan of mesh sized to pass the glass particles but not the paper fluff balls, whereby the glass particles fall through the screen and are thereby separated from the paper fluff balls, which remain on the screen for subsequent removal. 
     
     
       42. The method of claim 41, wherein said gyratory screen device comprises a screen of mesh sized to separate the glass particles into streams of coarser and finer particles, wherein the paper fibers tend to be mixed primarily with the finer particles, and wherein the stream of finer particles and paper fluff balls is supplied to said vibratory screen device for separation of the paper fluff balls from the glass particles. 
     
     
       43. The method of claim 41, wherein said vibratory screen device comprises a second pan disposed beneath said first pan and arranged to collect the glass particles falling through the mesh screen surface. 
     
     
       44. The method of claim 41, wherein said first pan of said vibratory screen device is divided longitudinally by a divider into two or more parallel aisles, wherein the mesh sizes of said screen sections of said pan differ in said aisles, and where differently-sized streams of glass particles with paper admixed therewith are supplied to said two or more aisles from said gyratory screen device.