CA1328862C - Method and apparatus for fine grinding - Google Patents
Method and apparatus for fine grindingInfo
- Publication number
- CA1328862C CA1328862C CA000583552A CA583552A CA1328862C CA 1328862 C CA1328862 C CA 1328862C CA 000583552 A CA000583552 A CA 000583552A CA 583552 A CA583552 A CA 583552A CA 1328862 C CA1328862 C CA 1328862C
- Authority
- CA
- Canada
- Prior art keywords
- mill
- cryogen
- grinding
- ground
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
- B02C23/18—Adding fluid, other than for crushing or disintegrating by fluid energy
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C13/00—Disintegrating by mills having rotary beater elements ; Hammer mills
- B02C13/14—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C19/00—Other disintegrating devices or methods
- B02C19/18—Use of auxiliary physical effects, e.g. ultrasonics, irradiation, for disintegrating
- B02C19/186—Use of cold or heat for disintegrating
Landscapes
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Disintegrating Or Milling (AREA)
Abstract
ABSTRACT
A method and apparatus for fine grinding materials normally difficult to grind at ambient temperature, e.g. plastic and elastomeric materials and foodstuffs in a fluid classification type impact mill utilizing liq-uid cryogen to pre-cool the material to be ground, to cool the material and the mill during grinding and to recycle vaporized cryogen from the mill back into the mill as the medium for conveying material to be ground into the mill.
A method and apparatus for fine grinding materials normally difficult to grind at ambient temperature, e.g. plastic and elastomeric materials and foodstuffs in a fluid classification type impact mill utilizing liq-uid cryogen to pre-cool the material to be ground, to cool the material and the mill during grinding and to recycle vaporized cryogen from the mill back into the mill as the medium for conveying material to be ground into the mill.
Description
1 32~62 METHOD AND APPA~ATUS FOR FINE GRINDING
TECF~ICU, FIELD
The present invention eertains to fine grinding and especially to fine grinding of plastic and elastomeric materials and foodstuffs.
sACKG20UND OF THE PRIOR AkT
Fine grinding, pulveri~ing or size reduction all terms used to denote comminution of relatively so~t or resilient materials ~uch as rubbers and plastics has been the subject of a great deal of interest and research for many years. In particular the rubber and plastic~ indu3try has been interested in fine grinding scrap or reject material in order to recycl~
10 the material for reuse. However, in order to make effective use of recycle material the recycle material must be ground to a particle ~ize finer than 80 mesh in order to be mixed ~ith virgin material for reuse.
An effective and economically cost justifiable fine griDding sy~tem would be an asset to the rubber and plastics industry because of the variou~
~ 15 states and the federal government making it re and ~ore difficult to dis-¦~ pose of scrap rubber and plastic material. Currently there is no economical process for producing powdered rubber or plastic of a particle size finer than 80 me h. Thus large amounts of scrap and reject material are being stoc~piled for recycle or disposition in accordance with current environ- -~` 20 mental la~s.
1~ In the past several attempt~ have been made to solve the problem of 1~ fine grinding by uti}izing~different types of grinding (pulverizing, size I reducing or comminution) mill~ which incorporate a liguid cryogen such as -~ liquid nitrogsn either before or in~ide the mill.
For example conventional hammer mills have utilized liguid nitrogen both inside the mill and before the mill in a pre-cooler. However over the past decade within which these devices have been used it ha~ been found that the hammer mill cannot grind the tough rubber and plastics economically be-cause of the escessive amount of liquid nitrogen required. ~
1 32~862 Attrition mills have also been modified to use liquid nitrogen both inside and befors the mill in a pre-cooler. This also has been done for about 10 years and it is known that the attrition mill cannot grind the tough rubber and plastics economically due to excessive plate wear inside S the mill.
Lastly air-swept impact mills ~fluid classification mills) have been utilized with nitrogen to pre-cool the material to be ground. Although a fine ground material was obtained the economics of the proce3s were un-favorable due to the excessive amounts of liguid nitrogen required.
The art i8 replete with variou~ types of whemes to utilize liquid nitrogen in combination with a grinding mill to effect the grinding of normally resilient or soft ~aterialR. U.S. Patents 2,609,150, 2,735,624, 2,919,862, 3,614,001, 3,771,729 and 4,273,294 illustrate the use of a liquid cryogen (liguid nitrogen) to pre-cool and~or cool the grinding mill to 15 achieve a ground product.
U.S. Patent 3,771,729 shows a particularly effective pre-cooling ap-¦ paratus for conditioning the material for grinding.
Other techniques for grinding materials that are normally soft, vis-cous, plastic or elastomeric in nature at room temperature are illustrated 20 in U.S. Patents 441,951, 637,465, 2,467,318, 3,314,802, 2,347,464, 2,435,503,2,583,697, 3,647,149, 3,658,259, 2,665,850, 3,734,412, 2,836,368, 2,893,216, 2,974,883, 3,319,895.
1~ SUMMARY OF THE INVENTION
j~ 25The present invention pertains to a method and apparatus for fine grinding ~e.g. to a -40 mesh particle size) of plastic and elastomeric materials utilizing a fluid classification impact grinding mill combined ~ with a liguid cryogen system to ere-cool the material to be ground, ¦-~ utilizing liquid cryogen inside the mill to cool the material during ~; 30 grinding which also cools the mill and recycling vaporized liquid cryogen 3~ for use as the classifying fluid or the sweep fluid for the mill.
~ BRIEF DESCRIPTION OF THE DRAWING
j FIG. 1 is a schematic elevational view of the system and method ac-35 cording to the present invention.
. - -:
~ ~ .
~ ! - ;
FIG. 2 is a front elevational view, partially in section, of a fluid cla~sification mill modified in accordance with the present invention.
FIG. 3 is a view taken along line 3-3 of FIG. 2.
FIG. 4 is a bottom plan vie~ of the manifold according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1 the overall system according to the invention is designated generally by the numeral 10. Sy~tem 10 includes as the central 10 apparatus a fluid classification impact mill 12 such as offered for sale by Mikropul Division of Hosokawa Micron International Inc., Summit, New Jersey, 07910, under the product designation AC~ ~icro Pulverizer.
Naterial i8 conveyed to the mill 12 for grinding by means of a transi-tion chute 14 which i3 connected to an air lock 16 which in turn is con-15 nected to a cooling conveyor 18. Cooling conveyor 18 is preferably of thetype shown and described in U.S. Patent 3,771,729 and offered for sale by Air Products and Chemicals, Inc., Trexlertown, Pennsylvania under the Cryo-Grind trademark. Cooling conveyor 18 has a feed hopper 22 as well as a conduit 24 for admitting liguid cryogen to the conveyor as shown in the 20 '729 patent. Conveyor 18 can be of any type that will provide means fo~
pre-c~oling the material to be qround to its embrittlement temperature.
Cooling conveyor 18 can be conveniently dispoced on a portable carriage or table 26 and includes dive mechanism 23. Do~nstream of mill 12 and con-nected to mill 12 via suitable piping 30 is a separator 32 such as a cyclone 25 separator. Cyclone separator 32 has disposed at its discharge opening an air lock 34 to permit discharge of the product into a receptacle or drum 36 without opening the system to ambient atmosphere.
A recycle blower 38 receives the vaporized cryogen exiting mill 12, after separation of the product 37 through ~uitable fluid tight connections 30 and piping 40. Recycle blower 38 convey~ the separated va~orized cryogen back to the mill 12 by means of conduit assembly 42 which includes a pres-sure relief valve 44.
A suitable conduit 46 conveys liquid cryogen to the mill 12 in a mannee a~ will hereinafter be more fully disclosed.
,~ .
;
~, . . . . .
The process according to the invention as practiced in tha apparatus or sy~tem of FIG. 1 takes place by i~troducing material to be ground to the cooling conveyor 18 by means of the hopper 22 and air lock 20. A~ the material is conveyed through the cooling conveyor 18 it i~ pre-cool~d by S liquid nitrogen introduced to the cooling conveyor through conduit 2~ to cool the material to its embrittling temperature. The material after cooling in cooling conveyor 18 i~ conveyed through a suitable air lock 16 and transition chute l~ to the fluit clas~ification impact mill 12. A~ i~
well known in the art mill 12 can be adjusted to provide product of a given lO fineness. In the case of the present invention the mill i~i set to grind thestarting material to a size that will pase through an 80 me~h (U.S. Standard) screen. The fine ground material entrained in vaporized cryogen exits the mill 12 in the direction shown by arrow 48 and enters the classifier or cyclone 32 where the particle~ shown by arrow 50 are separated from the 15 vaporized cryogen and collected as product 3~ in product drum 36. The vaporized cryogen exiting the cyclone 32 is conveyed by conduit 40 to the inlet or suction side of blower 38 ~hereby it is recycled to the ~luid classification mill 12 to be u~ied a~ the cla~sification fluid a3 will here- -inafter be more fully explained. Thus material processed accordinq to the 20 present invention can be finely ground very effectively. The proces~ i~
economical because the vaporized crycgen i~ recycled to be used as a classification fluid but more importantly the low temperature of the vaporized cryogen is utilized as an aid in cooling of the incoming produet and the mill.
The proce~s according to the Eresent invention can be operated effec~
tively with the following process conditions:
Table 1 Piece of Equipment Process Variable OPeratinq Limits Cooling Conveyor Temperature 0F to -320F
Cooling Conveyor Speed 0 to 100 volts Fluid Clas~ification Mill Temperature +70F to -320P
Fluid Classification Mill Classifier Speed O to 5000 rpm Blower Speed 100 to 3500 rpm ,~, .
-. .
,.~... .
:'' ', ' ' .' , ' : ' ' . ' ~ 328862 Mo8t common materials can be ground to size utilizing the parameter~ set out above. Experimentation has ~hown if the process i8 operated significantly outside the above limits the particle size required cannot be produced economically.
Scrap or recycle tire tread has been qround successfully utilizing the process of the psesent invention which material has been incorporated into virgin material for remolding.
FIG. 2 shows a fluid classification grinding mill such as the ACM Mikro pulverizer identified abo~e which ha~ been modified in accord with the pres-10 ent invention. Mill 12 includes an inlet chamber 60 containing an inlet conduit 64 which in turn i8 connected to the transition chute 14 of FIG. 1 by suitable fittings (not shown). Chamber 60 contains means for supporting a central rotor 64 which in turn is connected to the pin rotor 66 which 8Up-ports a plurality of hammers 68. Chamber 60 has mounted thereon a hou~ing ~-15 70 which in turn supports a second housing ~2 which contain~ an outlet con-duit 74 which i~ turn is connected to the piping 30 as shown in FIG. 1.
Disposed within housings 70 and 72 i~ a separator shaft and bearing hous-~ ing 74 which in turn supports the rotatable classifier 76. Disposed within ¦~ housing 70 and surrounding a pcrtion of the rotating classifier 76 is a ¦~ 20 shroud and baffle ring 78 Material to be ground is introduced to the mill 12 via a feed hopper and auger device 14 as i9 well known in the art. This basically is the conventional fluid classification impact grinding mill. In normal operation the material to be ground enters the mill and is contacted by hammers 68. A classification fluid (e.g. nitrogen) enters the mill 2S through inlet conduit 64 as shown by arrows 80 and flows through the mill ~o drive the particles in the direction shown by the arrows. The ground -, particles pass through the cliassifier 76 in accordance with the speed of ,~ rotation of the classifier and the selected particles are removed with the nitrogen via the arrows as shown. According to the pre~ent invention a ,~ 30 spray header or manifold 82 is disposed inside of the shroud and baffle ring l~ 78. Spray header 82 is adaptet to direct liquid cryogen, e.g. liguid nitro-gen in the direction shown by the hollow arrows 84. Spray header 82 is in turn connected through a suitable fitting 86 to a source of liquid cryogen , ~not shown). Spray header 82 can be di3posed at the top of the shroud and '~ 3S
, j ~ .
,. :
baffls ring, at the bottom thereof as ~hown by the ghost line~ or at any position intermediate thereof depending upon the mill and the degree of cooling and liquid cryogen consumption required. Tests have shown most economical use of liquid cryogen i9 effected when spray header 82 is dis-posed at the bottom of shroud and baffle ring 78. Liquid cryogen injectedinto the mill c0019 not only the mill, but the product as it is being ground. As the cryogen contacts the particles to be ground, it warms u~
and it vaporizes the vapors forming part of the product arrows 85 which leave the mill 12 and are conducted towards the cyclone 32 for separation 10 and recycled to the mill as hereinbefore described.
Figure 3 shows the shroud and baffle 78 and the housing 70 as well as the spray header 82. Spray header 82 as shown in Figure 4 i~ basically a circular tube containing a plurality of orifices or hole~ 90 for directing the liquid nitrogen towards the product being ground. Spray header 82 i9 15 constructed with a suitable manifold 94 so that the liquid crycgen entering the inlet conduit 96 passes to the orifices 90 without diminution.
Utilizing the method and apparatus according to the present invention of the total volume of liquid cryogen ~e.g. liquid nitrogen) used, 10-20~ i use~ in the precooler with the balance being used for direct injection into 20 the mill. -' -'.
'' '~
---~5 ` `
TECF~ICU, FIELD
The present invention eertains to fine grinding and especially to fine grinding of plastic and elastomeric materials and foodstuffs.
sACKG20UND OF THE PRIOR AkT
Fine grinding, pulveri~ing or size reduction all terms used to denote comminution of relatively so~t or resilient materials ~uch as rubbers and plastics has been the subject of a great deal of interest and research for many years. In particular the rubber and plastic~ indu3try has been interested in fine grinding scrap or reject material in order to recycl~
10 the material for reuse. However, in order to make effective use of recycle material the recycle material must be ground to a particle ~ize finer than 80 mesh in order to be mixed ~ith virgin material for reuse.
An effective and economically cost justifiable fine griDding sy~tem would be an asset to the rubber and plastics industry because of the variou~
~ 15 states and the federal government making it re and ~ore difficult to dis-¦~ pose of scrap rubber and plastic material. Currently there is no economical process for producing powdered rubber or plastic of a particle size finer than 80 me h. Thus large amounts of scrap and reject material are being stoc~piled for recycle or disposition in accordance with current environ- -~` 20 mental la~s.
1~ In the past several attempt~ have been made to solve the problem of 1~ fine grinding by uti}izing~different types of grinding (pulverizing, size I reducing or comminution) mill~ which incorporate a liguid cryogen such as -~ liquid nitrogsn either before or in~ide the mill.
For example conventional hammer mills have utilized liguid nitrogen both inside the mill and before the mill in a pre-cooler. However over the past decade within which these devices have been used it ha~ been found that the hammer mill cannot grind the tough rubber and plastics economically be-cause of the escessive amount of liquid nitrogen required. ~
1 32~862 Attrition mills have also been modified to use liquid nitrogen both inside and befors the mill in a pre-cooler. This also has been done for about 10 years and it is known that the attrition mill cannot grind the tough rubber and plastics economically due to excessive plate wear inside S the mill.
Lastly air-swept impact mills ~fluid classification mills) have been utilized with nitrogen to pre-cool the material to be ground. Although a fine ground material was obtained the economics of the proce3s were un-favorable due to the excessive amounts of liguid nitrogen required.
The art i8 replete with variou~ types of whemes to utilize liquid nitrogen in combination with a grinding mill to effect the grinding of normally resilient or soft ~aterialR. U.S. Patents 2,609,150, 2,735,624, 2,919,862, 3,614,001, 3,771,729 and 4,273,294 illustrate the use of a liquid cryogen (liguid nitrogen) to pre-cool and~or cool the grinding mill to 15 achieve a ground product.
U.S. Patent 3,771,729 shows a particularly effective pre-cooling ap-¦ paratus for conditioning the material for grinding.
Other techniques for grinding materials that are normally soft, vis-cous, plastic or elastomeric in nature at room temperature are illustrated 20 in U.S. Patents 441,951, 637,465, 2,467,318, 3,314,802, 2,347,464, 2,435,503,2,583,697, 3,647,149, 3,658,259, 2,665,850, 3,734,412, 2,836,368, 2,893,216, 2,974,883, 3,319,895.
1~ SUMMARY OF THE INVENTION
j~ 25The present invention pertains to a method and apparatus for fine grinding ~e.g. to a -40 mesh particle size) of plastic and elastomeric materials utilizing a fluid classification impact grinding mill combined ~ with a liguid cryogen system to ere-cool the material to be ground, ¦-~ utilizing liquid cryogen inside the mill to cool the material during ~; 30 grinding which also cools the mill and recycling vaporized liquid cryogen 3~ for use as the classifying fluid or the sweep fluid for the mill.
~ BRIEF DESCRIPTION OF THE DRAWING
j FIG. 1 is a schematic elevational view of the system and method ac-35 cording to the present invention.
. - -:
~ ~ .
~ ! - ;
FIG. 2 is a front elevational view, partially in section, of a fluid cla~sification mill modified in accordance with the present invention.
FIG. 3 is a view taken along line 3-3 of FIG. 2.
FIG. 4 is a bottom plan vie~ of the manifold according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1 the overall system according to the invention is designated generally by the numeral 10. Sy~tem 10 includes as the central 10 apparatus a fluid classification impact mill 12 such as offered for sale by Mikropul Division of Hosokawa Micron International Inc., Summit, New Jersey, 07910, under the product designation AC~ ~icro Pulverizer.
Naterial i8 conveyed to the mill 12 for grinding by means of a transi-tion chute 14 which i3 connected to an air lock 16 which in turn is con-15 nected to a cooling conveyor 18. Cooling conveyor 18 is preferably of thetype shown and described in U.S. Patent 3,771,729 and offered for sale by Air Products and Chemicals, Inc., Trexlertown, Pennsylvania under the Cryo-Grind trademark. Cooling conveyor 18 has a feed hopper 22 as well as a conduit 24 for admitting liguid cryogen to the conveyor as shown in the 20 '729 patent. Conveyor 18 can be of any type that will provide means fo~
pre-c~oling the material to be qround to its embrittlement temperature.
Cooling conveyor 18 can be conveniently dispoced on a portable carriage or table 26 and includes dive mechanism 23. Do~nstream of mill 12 and con-nected to mill 12 via suitable piping 30 is a separator 32 such as a cyclone 25 separator. Cyclone separator 32 has disposed at its discharge opening an air lock 34 to permit discharge of the product into a receptacle or drum 36 without opening the system to ambient atmosphere.
A recycle blower 38 receives the vaporized cryogen exiting mill 12, after separation of the product 37 through ~uitable fluid tight connections 30 and piping 40. Recycle blower 38 convey~ the separated va~orized cryogen back to the mill 12 by means of conduit assembly 42 which includes a pres-sure relief valve 44.
A suitable conduit 46 conveys liquid cryogen to the mill 12 in a mannee a~ will hereinafter be more fully disclosed.
,~ .
;
~, . . . . .
The process according to the invention as practiced in tha apparatus or sy~tem of FIG. 1 takes place by i~troducing material to be ground to the cooling conveyor 18 by means of the hopper 22 and air lock 20. A~ the material is conveyed through the cooling conveyor 18 it i~ pre-cool~d by S liquid nitrogen introduced to the cooling conveyor through conduit 2~ to cool the material to its embrittling temperature. The material after cooling in cooling conveyor 18 i~ conveyed through a suitable air lock 16 and transition chute l~ to the fluit clas~ification impact mill 12. A~ i~
well known in the art mill 12 can be adjusted to provide product of a given lO fineness. In the case of the present invention the mill i~i set to grind thestarting material to a size that will pase through an 80 me~h (U.S. Standard) screen. The fine ground material entrained in vaporized cryogen exits the mill 12 in the direction shown by arrow 48 and enters the classifier or cyclone 32 where the particle~ shown by arrow 50 are separated from the 15 vaporized cryogen and collected as product 3~ in product drum 36. The vaporized cryogen exiting the cyclone 32 is conveyed by conduit 40 to the inlet or suction side of blower 38 ~hereby it is recycled to the ~luid classification mill 12 to be u~ied a~ the cla~sification fluid a3 will here- -inafter be more fully explained. Thus material processed accordinq to the 20 present invention can be finely ground very effectively. The proces~ i~
economical because the vaporized crycgen i~ recycled to be used as a classification fluid but more importantly the low temperature of the vaporized cryogen is utilized as an aid in cooling of the incoming produet and the mill.
The proce~s according to the Eresent invention can be operated effec~
tively with the following process conditions:
Table 1 Piece of Equipment Process Variable OPeratinq Limits Cooling Conveyor Temperature 0F to -320F
Cooling Conveyor Speed 0 to 100 volts Fluid Clas~ification Mill Temperature +70F to -320P
Fluid Classification Mill Classifier Speed O to 5000 rpm Blower Speed 100 to 3500 rpm ,~, .
-. .
,.~... .
:'' ', ' ' .' , ' : ' ' . ' ~ 328862 Mo8t common materials can be ground to size utilizing the parameter~ set out above. Experimentation has ~hown if the process i8 operated significantly outside the above limits the particle size required cannot be produced economically.
Scrap or recycle tire tread has been qround successfully utilizing the process of the psesent invention which material has been incorporated into virgin material for remolding.
FIG. 2 shows a fluid classification grinding mill such as the ACM Mikro pulverizer identified abo~e which ha~ been modified in accord with the pres-10 ent invention. Mill 12 includes an inlet chamber 60 containing an inlet conduit 64 which in turn i8 connected to the transition chute 14 of FIG. 1 by suitable fittings (not shown). Chamber 60 contains means for supporting a central rotor 64 which in turn is connected to the pin rotor 66 which 8Up-ports a plurality of hammers 68. Chamber 60 has mounted thereon a hou~ing ~-15 70 which in turn supports a second housing ~2 which contain~ an outlet con-duit 74 which i~ turn is connected to the piping 30 as shown in FIG. 1.
Disposed within housings 70 and 72 i~ a separator shaft and bearing hous-~ ing 74 which in turn supports the rotatable classifier 76. Disposed within ¦~ housing 70 and surrounding a pcrtion of the rotating classifier 76 is a ¦~ 20 shroud and baffle ring 78 Material to be ground is introduced to the mill 12 via a feed hopper and auger device 14 as i9 well known in the art. This basically is the conventional fluid classification impact grinding mill. In normal operation the material to be ground enters the mill and is contacted by hammers 68. A classification fluid (e.g. nitrogen) enters the mill 2S through inlet conduit 64 as shown by arrows 80 and flows through the mill ~o drive the particles in the direction shown by the arrows. The ground -, particles pass through the cliassifier 76 in accordance with the speed of ,~ rotation of the classifier and the selected particles are removed with the nitrogen via the arrows as shown. According to the pre~ent invention a ,~ 30 spray header or manifold 82 is disposed inside of the shroud and baffle ring l~ 78. Spray header 82 is adaptet to direct liquid cryogen, e.g. liguid nitro-gen in the direction shown by the hollow arrows 84. Spray header 82 is in turn connected through a suitable fitting 86 to a source of liquid cryogen , ~not shown). Spray header 82 can be di3posed at the top of the shroud and '~ 3S
, j ~ .
,. :
baffls ring, at the bottom thereof as ~hown by the ghost line~ or at any position intermediate thereof depending upon the mill and the degree of cooling and liquid cryogen consumption required. Tests have shown most economical use of liquid cryogen i9 effected when spray header 82 is dis-posed at the bottom of shroud and baffle ring 78. Liquid cryogen injectedinto the mill c0019 not only the mill, but the product as it is being ground. As the cryogen contacts the particles to be ground, it warms u~
and it vaporizes the vapors forming part of the product arrows 85 which leave the mill 12 and are conducted towards the cyclone 32 for separation 10 and recycled to the mill as hereinbefore described.
Figure 3 shows the shroud and baffle 78 and the housing 70 as well as the spray header 82. Spray header 82 as shown in Figure 4 i~ basically a circular tube containing a plurality of orifices or hole~ 90 for directing the liquid nitrogen towards the product being ground. Spray header 82 i9 15 constructed with a suitable manifold 94 so that the liquid crycgen entering the inlet conduit 96 passes to the orifices 90 without diminution.
Utilizing the method and apparatus according to the present invention of the total volume of liquid cryogen ~e.g. liquid nitrogen) used, 10-20~ i use~ in the precooler with the balance being used for direct injection into 20 the mill. -' -'.
'' '~
---~5 ` `
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for utilizing a fluid classification impact grinding mill for fine grinding in a closed system comprising the steps of:
pre-cooling the material to be ground to a temperature below its embrittlement temperature;
injecting said pre-cooled material into said mill while simultaneously injection a liquid cryogen into said mill;
recovering said ground material and cryogen vaporized in said mill;
separating said vaporized cryogen from said ground material and recycling said vaporized cryogen to said mill as a classi-fying medium.
pre-cooling the material to be ground to a temperature below its embrittlement temperature;
injecting said pre-cooled material into said mill while simultaneously injection a liquid cryogen into said mill;
recovering said ground material and cryogen vaporized in said mill;
separating said vaporized cryogen from said ground material and recycling said vaporized cryogen to said mill as a classi-fying medium.
2. A method according to Claim 1 wherein said liquid cryo-gen is nitrogen.
3. A method according to Claim 1 wherein said pre-cooling is accomplished by utilizing liquid cryogen.
4. A method according to Claim 1 wherein said ground material is recovered as a product.
5. A method according to Claim 1 wherein said ground material has a particle size that will pass a 40 mesh screen.
6. A closed system for fine grinding rubber and plastic material comprising in combination means for collecting and conveying said material to a fluid classification grinding mill said means including means to pre-cool said material to below its embrittlement temperature;
a fluid classification grinding mill connected in fluid tight relation to said collecting and conveying means said mill including means to inject a liquid cryogen onto said material during grinding:
removal means to conduct ground material and cryogen vapori-zed in said mill to separator means;
separator means to separate such ground material from said vaporized cryogen;
recirculation means to convey such vaporized cryogen from said separator means to said mill; and collection means to recover said ground material as a product.
a fluid classification grinding mill connected in fluid tight relation to said collecting and conveying means said mill including means to inject a liquid cryogen onto said material during grinding:
removal means to conduct ground material and cryogen vapori-zed in said mill to separator means;
separator means to separate such ground material from said vaporized cryogen;
recirculation means to convey such vaporized cryogen from said separator means to said mill; and collection means to recover said ground material as a product.
7. A system according to Claim 6 wherein said collecting and con-veying means includes a feed hopper and a cooling conveyor with an air lock therebetween.
8. A system according to Claim 6 wherein an air lock is disposed between said collecting and conveying means and said fluid classification grinding mill.
9. A system according to Claim 6 wherein said separator means in-cludes a cyclone type separator.
10. A system according to Claim 6 wherein said recirculation means includes a blower the suction side connected to said mill through said cyclone and said output connected to said fluid classification mill.
11. In a fluid classification type grinding mill of the type wherein a normal gaseous fluid is used to convey particles to be ground into the mill and ground particles out of such mill, the improvement comprising:
means to inject a liquid cryogen into the particles during grind-ing to cool said particles and said mill.
means to inject a liquid cryogen into the particles during grind-ing to cool said particles and said mill.
12. An apparatus according to Claim 11 wherein said means includes a spray header disposed in said mill above active grinding devices with means to direct said cryogen toward said active grinding devices.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12563887A | 1987-11-25 | 1987-11-25 | |
| US125,638 | 1987-11-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1328862C true CA1328862C (en) | 1994-04-26 |
Family
ID=22420699
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000583552A Expired - Fee Related CA1328862C (en) | 1987-11-25 | 1988-11-18 | Method and apparatus for fine grinding |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0317935B1 (en) |
| JP (1) | JPH01168361A (en) |
| KR (1) | KR910006231B1 (en) |
| BR (1) | BR8806087A (en) |
| CA (1) | CA1328862C (en) |
| DE (1) | DE3870587D1 (en) |
| PT (1) | PT89070A (en) |
| ZA (1) | ZA888809B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5164132A (en) * | 1991-04-05 | 1992-11-17 | Air Products And Chemicals, Inc. | Process for the production of ultra-fine polymeric fibers |
| CH688269A5 (en) * | 1992-08-21 | 1997-07-15 | Debio Rech Pharma Sa | Ultra Centrifugal Mill and its implementation for cryogenic grinding of thermally sensitive material. |
| IT1271454B (en) * | 1993-01-28 | 1997-05-28 | Pro Co Gen Progettazioni E Cos | CRYOTRANSFORMATION PLANT AND SELECTION OF SOLID URBAN WASTE. |
| DE19533078A1 (en) * | 1995-09-07 | 1997-03-13 | Messer Griesheim Gmbh | Method and device for grinding and classifying regrind |
| ES2188329B1 (en) * | 2000-09-15 | 2004-12-01 | Consejo Superior De Investigaciones Cientificas | PREPARATION PROCEDURE THROUGH CRIOGENIC GRINDING OF AROMATIC POLYESTER MIXTURES WITH TRANSESTERIFICATION GRADE CONTROL. |
| CA2680185A1 (en) * | 2007-03-06 | 2008-09-12 | Archer-Daniels-Midland Company | Method and apparatus for producing cocoa products |
| KR100842300B1 (en) * | 2007-05-21 | 2008-06-30 | 한국기계연구원 | Powder classification and separation apparatus media mill system |
| CN103272674B (en) * | 2013-05-22 | 2015-12-02 | 张家港市华丰油脂有限公司 | A kind of air-flow vortex pulverizing mill for extracting cotton protein from cotton dregs |
| CN110026283B (en) * | 2019-04-09 | 2020-08-11 | 凤台县农盼水稻机插服务专业合作社 | Low-temperature crop straw smashing device and operation method thereof |
| EP3764030A1 (en) * | 2019-07-11 | 2021-01-13 | Air Liquide Deutschland GmbH | Method and device for cooling products |
| US11872593B1 (en) * | 2023-04-21 | 2024-01-16 | AGT-USA, Inc. | Cryogenic processing system for plant material |
| US11766678B1 (en) | 2023-04-21 | 2023-09-26 | AGT-USA, Inc. | Cryogenic processing system for plant material |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3771729A (en) * | 1971-06-17 | 1973-11-13 | Air Prod & Chem | Cryogenic comminution system |
| JPS5472563A (en) * | 1977-11-21 | 1979-06-11 | Nippon Oxygen Co Ltd | Method of low temperature crushing |
| US4222527A (en) * | 1979-02-22 | 1980-09-16 | Union Carbide Corporation | Cryopulverizing packed bed control system |
| DE2952363A1 (en) * | 1979-12-24 | 1981-07-02 | Linde Ag, 6200 Wiesbaden | METHOD AND DEVICE FOR CRUSHING SUBSTANCES AT LOW TEMPERATURES |
-
1988
- 1988-11-18 CA CA000583552A patent/CA1328862C/en not_active Expired - Fee Related
- 1988-11-21 EP EP88119353A patent/EP0317935B1/en not_active Expired - Lifetime
- 1988-11-21 BR BR888806087A patent/BR8806087A/en not_active IP Right Cessation
- 1988-11-21 DE DE8888119353T patent/DE3870587D1/en not_active Expired - Lifetime
- 1988-11-22 JP JP63295906A patent/JPH01168361A/en active Pending
- 1988-11-24 ZA ZA888809A patent/ZA888809B/en unknown
- 1988-11-24 PT PT89070A patent/PT89070A/en not_active Application Discontinuation
- 1988-11-25 KR KR1019880015558A patent/KR910006231B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR890007796A (en) | 1989-07-05 |
| ZA888809B (en) | 1990-07-25 |
| PT89070A (en) | 1989-09-14 |
| EP0317935A3 (en) | 1990-01-03 |
| BR8806087A (en) | 1989-08-08 |
| EP0317935A2 (en) | 1989-05-31 |
| JPH01168361A (en) | 1989-07-03 |
| KR910006231B1 (en) | 1991-08-17 |
| DE3870587D1 (en) | 1992-06-04 |
| EP0317935B1 (en) | 1992-04-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5203511A (en) | Method for fine grinding | |
| CA1328862C (en) | Method and apparatus for fine grinding | |
| US5588600A (en) | Process and apparatus for making crumb rubber from vehicle tires | |
| EP1685163B1 (en) | Process and apparatus for manufacturing crumb and powder rubber | |
| US4025990A (en) | Process for reclaiming rubber, metal and fabric from whole tires | |
| US2879005A (en) | Method of refining scrap plastic and apparatus therefor | |
| US4863106A (en) | Process for low temperature comminution of scrap tires | |
| CA1149357A (en) | Method and apparatus for cryogenic grinding | |
| RU2283759C2 (en) | Scrap rubber recycling plant | |
| KR100268981B1 (en) | Ultra-high energy cryogenic impact system | |
| US5195695A (en) | Apparatus for fine grinding | |
| CN107511392A (en) | A kind of electron wastes harmless disassembly and resource classification reclaimer and method | |
| US5887803A (en) | Process and apparatus for grinding and sifting a product | |
| EP0222760B1 (en) | Comminution of coal, ores and industrial minerals and rocks | |
| DE2318549A1 (en) | CRYOGENIC CRUSHING PROCESS | |
| CA1189046A (en) | Apparatus for and method of shredding cans | |
| JPH05253506A (en) | Vertical type crushing device | |
| KR0150229B1 (en) | Method and apparatus for pulverizing difficult for crushing plastic materials | |
| DE10059442A1 (en) | Device and method for producing fine material from chemically active regrind | |
| HU211770B (en) | Arrangement and apparatus for handling grinding, recycling of rubber-wastes | |
| LT5314B (en) | Device for recycling rubber-containing waste | |
| JP2001219426A (en) | Method and apparatus for recovering spent edible oil packaging container made of thermoplastic resin |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 19990426 |