Fluorescent tube crusher with particulate separation and recovery

A digester for scrap fluorescent tubes comprising:

• (a) a rotatable fracture blade for impacting used fluorescent tubes to fracture said tubes into small pieces,
• (b) said rotatable fracture blade having a width not substantially greater than the diameter of the fluorescent tubes,
• (c) a casing surrounding the rotatable blade having inner dimensions not substantially greater than the outer dimensions of the rotatable blade,
• (d) a lower extension on the casing through which glass particulates may pass downwardly countercurrently with upwardly passing stripping gas,
• (e) a stripping gas takeoff intermediately positioned between a portion of the casing surrounding the fracture blade and the lower extension, and
• (f) means for drawing a substantial flow of a stripping gas through the casing during operation to strip dust and gas from residual fractured glass particulates within said casing resulting from rotation of said fracture blade against fluorescent tubes inserted into said casing.

A digester for scrap fluorescent tubes for decreasing bulk of the glass components of such tubes and allowing use of the component glass for recycling while collecting toxic dust and fumes for separate safe disposal comprising:

• (a) a fracture chamber incorporating a rotatable chopping blade,
• (b) a countercurrent flow chamber adjoining and interconnected with the bottom of the fracture chamber,
• (c) a gas take-off in the vicinity of the interconnection of the countercurrent flow chamber and the fracture chamber,
• (d) the countercurrent flow chamber being open at the lower end to an expanded particulate collection chamber,
• (e) the countercurrent flow chamber, fracture chamber, gas take-off and inlets to the fracture chamber and countercurrent flow chamber being dimensioned and interconnected such that when a suction is applied to the gas take-off, a rapid flow of gas is established through the fracture chamber and the countercurrent flow chamber, with the velocity of flow through the countercurrent flow chamber being an order of approximately one hundred times the velocity of flow through the fracture chamber.

A digester system for scrap fluorescent tubes for decreasing the bulk of glass components of such tubes and allowing use of the component glass for recycling while collecting toxic dust and fumes for separate safe disposal comprising:

• (a) a casing arranged and constructed for substantially surrounding and enclosing a rotatable chopping blade for fracturing used fluorescent tubes into reduced-size individual glass particulates,
• (b) an enclosed feed chute passing into the chopping blade casing, said chute having an internal diameter such as to allow free passage of used fluorescent tubes therethrough, but with a restricted clearance at least in one portion of the chute to limit air passage down the chute when a fluorescent tube is passing therethrough,
• (c) a vertically rotatable tube chopping blade having a width not substantially greater than the diameter of the feed chute positioned to intersect fluorescent tubes passing down said feed chute into said casing,
• (d) said casing extending downwardly form the rotatable tube chopping blade toward a lower particulate outlet and having restricted internal dimensions such that a substantial flow of air at least through a lower portion of the casing between the particulate outlet and the rotatable chopper blade can be maintained during chopping of fluorescent tubes,
• (e) an offtake from the casing connected to a vacuum suction system means for drawing air from the casing and into a centrifugal separator means followed by a filter and mercury absorption means,
• (f) said offtake being positioned and the vacuum system being arranged and constructed such that a rapid flow of stripping air passes through the portion of the casing surrounding the fracture blade concurrently with movement of fractured glass particles through said upper portion of the casing and countercurrently through the lower portion of the casing with the descent of fractured glass particulates through the casing after fracturing by the tube chopping blade.

A method of digesting used fluorescent tubes for recycling of usable components and disposal of toxic components comprising:

• (a) chopping the fluorescent tubes into small particulates with a rotating chopper blade contained in a restricted clearance casing,
• (b) drawing a stream of air through the restricted clearance casing having a volume and velocity sufficient to remove and entrain in said air stream substantially all toxic powder and fumes released from the fluorescent tubes during fracturing thereof,
• (c) passing said stream of air containing toxic powder and fumes entrained therein into a centrifugal separator to separate the majority of the toxic powder entrained in the gas stream, and
• (d) passing the stream of air from the centrifugal separator to a filter and absorption system to remove residual particulate material and any toxic fume material, and
• (e) wherein the air stream which entrains the toxic powder and fumes enters the casing from two directions in two portions, one portion of which air stream passes through a first section of the restricted clearance casing surrounding the rotating chopper blade substantially concurrently with the fractured glass particulates formed by impact with the rotating chopper blade and the other portion of which air stream passes through a second portion of the restricted clearance casing below the rotating chopper blade countercurrently with the fractured glass particulates descending through the casing.

A method of digesting fluorescent tubes and separating residual components of said tubes comprising:

• (a) fracturing the tubes in a constricted fracturing volume with a rotating fracture blade,
• (b) passing a first rapid flow of stripping gas through the constricted fracturing volume while the tubes are being fractured into a particle size that is easily disposable in order to entrain loose powder material originally coating the inside of the tube,
• (c) passing particles of glass from the constricted fracturing volume together with entrained powder and stripping gas into a connecting constricted countercurrent gas stripping zone in opposition to a second rapid flow of stripping gas passing upwardly countercurrent to passage of the particles of glass,
• (d) removing said first and second rapid flows of gas simultaneously from a point where the constricted fracturing volume and the connected constricted countercurrent gas stripping zone interconnect, and
• (e) passing the rapid flows of gas as a combined flow through a series of powder removal devices to remove entrained powder from the combined gas flow.

A method of digesting used fluorescent tubes and separating the components of the tubes comprising:

• (a) passing a fluorescent tube into a constricted fracturing chamber where the tube is fractured into separate pieces by contact with a rotating fracturing blade,
• (b) drawing a first stream of air through said fracturing chamber substantially concurrently with the passage through and from said chamber of fractured glass particulates, the stream of air having a sufficient flow to entrain powder derived from powder deposits adherent to the inside of the unfractured tube, which powder becomes separated from the glass and glass particulates during fracturing and upon exposure of the glass particulates to the rapid flow of gas, and to prevent buildup of particulate and powder deposits in the fracturing chamber,
• (c) passing the glass particulates substantially downwardly into a second stream of air passing countercurrently with the glass particulates and having a countercurrent velocity sufficient to strip loose powder from original internal surface portions of the glass particulates and carry the powder upwardly, but insufficient to carry the majority of the glass particulates upwardly,
• (d) passing the first and second streams of air to a particulate removal arrangement to remove particulates of powder and small glass particles from the air streams.

A method of digesting used fluorescent tubes for recycling of usable components and disposal of toxic components comprising:

• (a) chopping the fluorescent tubes into small particulates with a rotating chopper blade contained in a first restricted clearance casing,
• (b) drawing a first stream of air through the first restricted clearance casing having a volume and velocity sufficient to remove and entrain in said air stream substantially all toxic powder and fumes released from the fluorescent tubes during fracturing thereof,
• (c) passing fractured glass particulates from said first restricted clearance casing generally downwardly into a second interconnected casing having restricted dimensions such that the longitudinal dimension of the second casing is at least several times the transverse dimension of said second casing,
• (d) drawing a second stream of generally vertically moving air through the second casing having a volume and velocity sufficient to remove and entrain in the air substantially all remaining toxic powder and fumes released from the fractured glass,
• (e) passing said streams of air containing toxic powder and fumes entrained therein into a centrifugal separator to separate the majority of the particulate matter entrained in the gas stream, and
• (f) passing the stream of air from the centrifugal separator to a filter and absorption system to remove residual particulate material and any toxic fume material.