US3658259A - Method for granule pulverization - Google Patents

Method for granule pulverization Download PDF

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Publication number
US3658259A
US3658259A US96805A US3658259DA US3658259A US 3658259 A US3658259 A US 3658259A US 96805 A US96805 A US 96805A US 3658259D A US3658259D A US 3658259DA US 3658259 A US3658259 A US 3658259A
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United States
Prior art keywords
gas
stream
jet mill
streams
admixed
Prior art date
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Expired - Lifetime
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US96805A
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English (en)
Inventor
Anton Ledergerber
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Inventa AG fuer Forschung und Patentverwertung
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Inventa AG fuer Forschung und Patentverwertung
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    • 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. ultrasonic waves or irradiation, for disintegrating
    • B02C19/186—Use of cold or heat for disintegrating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00—Conditioning or physical treatment of the material to be shaped
    • B29B13/10—Conditioning or physical treatment of the material to be shaped by grinding, e.g. by triturating; by sieving; by filtering
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S241/00—Solid material comminution or disintegration
    • Y10S241/37—Cryogenic cooling

Definitions

  • the material may be partly heated to melting point and the grinding effect is thereby reduced and the output of the mill is considerably decreased.
  • the grinding conditions can be considerably improved, since the brittleness and consequently the destructibility of the grains fed in are increased. In this manner, the expenditure of energy for grinding is considerably reduced as is the temperature increase within the mill.
  • This method has the disadvantage that uniform metering of the cooling medium is difficult to attain so that the maintenance of a precise temperature cannot be readily achieved.
  • the minimum grinding temperature' is limited by the vaporization temperature of the solid carbon dioxide.
  • the handling of this cooling medium is complicated and, in consequence of the high cost of procuring solid carbon dioxide, operation is very uneconomical.
  • liquid nitrogen is extremely expensive, and the controllability of the system is limited. Moreover, if there is direct contact of the liquid nitrogen with the product, a deterioration in the structure of the material and in the comminution properties of the material may be caused by the extremely low temperatures.
  • jet mills have the great drawback that the consumption of energy for producing a certain product area is several times greater than in mechanical mills, so that jet mills are not normally used for the production of cheap bulk goods, but only for high-grade products or where a high degree of fineness is required.
  • a jet mill is employed for fine grinding and a cold-gas circuit is employed for refrigeration, the required low temperatures being obtained by the expansion of a precooled stream of gas.
  • the expansion is carried out in conventional expansion machines for which purpose expansion turbines are used with advantage.
  • These turbines can either be braked electrically with the interposition of conventional gearing to obtain mechanical power to run other portions of the cold-gas circuit or directly with a blower, the second case also having the advantage, apart from simplicity, that a pre-compression of the recycle gas can be effected.
  • the process according to the invention is characterized by the grinding being carried out in a jet mill with the aid of a working gas stream which is taken from a cold-gas circuit which achieves the low temperature required for the working gas stream and for the precooling of the charging product by approximately isentropic expansion of a precooled and compressed recycle gas, this precooling being effected by heat exchange with expanded recycle gas obtained after its use for cooling the charging product and the removal of the generated heat of grinding.
  • the compression of the recycle gas may be effected only to the working pressure of the jet mill, following which the recycle gas is divided after precooling into two partial streams, the first of which is further cooled by expansion in a turbine.
  • the second partial stream is reduced to approximately the temperature of the first partial stream by heat exchange, whereupon the compressed second partial stream serves as the working gas stream for the jet mill, while the expanded first partial stream is employed for precooling the charging product.
  • Another way of carrying the process into effect consists in compressing the recycle gas to a pressure which is two to 30 atmospheres higher than the working pressure of the jet mill.
  • the entire amount of recycle gas is expanded to the pressure of the jet mill, whereupon the total stream is divided into two partial streams, one of which is used for precooling the charging product and the other as working gas stream forthev jet mill.
  • the partial stream which is not carried through the jet mill only has to be compressed to the compression pressure from the working pressure of the mill, thereby reducing the energy input necessary to carry out the process.
  • the preferred method of carrying the process into effect is that in which the partial stream which is not carried through the jet mill is expanded in another expansion stage to the outlet pressure of the jet mill, as -a result of which its temperature'is lowered further so that by-means-of heat exchange the working gas stream for the jet mill-canalso be cooled still further.
  • Air is preferably employed as recycle gas, since in this way the cost of replenishing the system in the event of leakage losses would probably be lowest.
  • other gases which are not liquified in the operating range of the turbines may also be employed.
  • air it is also possible to use a so-called open circuit and in this case precautions must be taken for eliminating foreign gases (for example, water vapor and CO which crystallize out at low temperatures from the circuit.
  • the process according to the invention allows the temperature during the grinding operation to be adjusted within wide limits and with simple means conventionally used in control engineering to any desired level and to be kept exactly constant at this level.
  • the adjustment may be effected by a variation of the pressure gradient in the refrigerating circuit, a variation of the amount of gas in circulation or of the amount of the partial stream passing through the mill, as well as by varying the effective heat-exchanger area.
  • the cost of the refrigeration by the new process is considerably lower than in the other processes that are known and handling is extremely simple. Due to the use of a refrigerating circuit for cooling the gas used in the grinding operation, a separate compressor for the jet mill can be saved, as a result of which the cost to construct the mill and the cost of its operation is greatly reduced.
  • H0. 1 illustrates an embodiment of the process according to the invention.
  • FIG. 2 illustrates a second embodiment of the process according to the invention.
  • the recycle gas is compressed by the compressor 14 to the pressure of the jet mill 7 and is freed from the heat of compression in the after-cooler 15 by means of cooling water.
  • the recycle gas is further precooled in the heat exchanger to a temperature determined by the existing gas pressure and the desired grinding temperature.
  • the recycle stream coming from the line 20 is branched into two partial streams, one partial stream being expanded in the turbine 2 and being cooled further in the process. Through the line 22 this partial stream enters the heat exchanger 3, where it absorbs heat by cooling the second partial stream flowing in through the line 21.
  • the first partial stream enters the fluidized bed cooler 5, where the plastics granules fed from the supply vessel 4 are precooled and are brought by way of the bucket lock 34, the line 35 and the conveyor worm 36 into the fluidized bed cooler 6, where the low-temperature cooling is effected by the second partial stream flowing in through the line 33.
  • the resulting mixture of granules and air passes into the jet mill 7, where the grinding into powder takes place.
  • the powder-charged second partial stream enters a cyclone separator 8 through the line 37 after being combined with the first partial stream from the line 25, in which separator the powder can be separated from the air and drawn off by way of the lock 38.
  • the recycled air, charged with fine residues of powder passes through the line 28 into the filter 9 and is finely purified therein.
  • the clean air is supplied through the line 29 to the heat exchanger 10, where it absorbs heat from the compressed air.
  • the purified preheated air is fed through the line 30 to the blower 12, is precompressed therein in accordance with the output available and, after cooling in the intermediate cooler 13, is supplied to th compressor 14 again, where the cycle begins afresh.
  • This partial stream passes through the line 22 into the heat exchanger 3, where it is conveyed in counter-current to the second partial stream,.which has been separated from the first partial stream via the line 21 at the intermediate pressure of six atmospheres absolute.
  • the first partial stream is heated from 157 to -l22 C. and passes through the line 23 into the fluidized bed cooler 5.
  • Plastics granules are fed to this cooler from the supply vessel 4 and are cooled from +20 to 1 10 C. by the first partial air stream.
  • the precooled granules pass through a bucket lock 34 into the line 35 and are conveyed by means of the conveyor worm 36 into the fluidized bed cooler 6, where they are cooled to 1 40 C. by the second partial air stream.
  • the second partial air stream leaves the heat exchanger 3 at a temperature of150 C. and is conveyed through the line 33 to the fluidized bed cooler 6, where the air becomes heated to 142 C.
  • the cold mixture of air and granules now enters the jet mill 7, where the air expands to a pressure of about 1.5 atmospheres absolute.
  • the temperature of the air is reduced to 130 C. and the air is then heated to l20 C. through turbulence and absorption of heat which is generated during the pulverization of the granules.
  • the plastic is ground in the mill into powder with a particle size of 100 to 200p..
  • the mixture of powder and air leaves the mill 7 by way of the line 37 and combines with the first partial air stream coming from the fluidized bed cooler 5 at a temperature of 113 C.
  • the powder is separated from the air in the cyclone separator 8 and can be drawn off via the lock 38.
  • the air charged with residues of fine powder passes to the filter 9 where the powder is retained and the pure air is drawn off through the line 29 and enters the heat exchanger 10 at a temperature of-l 16 C., being heated therein to l C. in counter-current to the compressed air. Due to the pressure losses of the various interposed pieces of apparatus, the pressure of the recycle air in the line 30 is about one atmosphere absolute.
  • the air stream is distributed between the two blowers 11 and 12 in accordance with the output available and is compressed therein to about 1.5 atmospheres absolute.
  • the recycle air arrives at the intermediate cooler 13 and from here at the compressor 14, where compression to 15 atmospheres absolute is effected.
  • the after-cooler 15 the heat of compression is transferred to cooling water and the air finally passes at a temperature of about 20 C. to the heat exchanger 10, where it is precooled to in counter-current to the low-pressure air, and in the end is again fed to the turbine 1, whereby the cycle recommences.
  • the pressures may vary within wide limits.
  • the pressure in advance of the turbine may be, for example, between five and 40 atmospheres absolute
  • the intermediate pressure between the turbines 1 and 2 may be three to 10 atmospheres absolute
  • the pressure in the low-pressure system may vary, for example, from 0.5 to two atmospheres absolute.
  • the temperatures may also range within wide limits, depending on the nature of the materials to be ground and the pressures employed.
  • a process for grinding granular material at low temperatures in ajet mill comprising the steps of contacting the granular material with a first stream of cold gas before the granular material is fed to the jet mill to precool said granular material, feeding the precooled granular material to the jet mill, pulverizing said granular material in said jet mill, by means of introducing an expanding second cold gas stream into said jet mill effecting the granular material being pulverized and to reduce the temperature of the granular material as it is being pulverized.
  • the process specified in claim 1 further including the steps of admixing the first and second gases downstream of the jet mill, separating the pulverized material from the admixed gases, and recycling the admixed gases to a cold gas circuit for reuse.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Food Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Disintegrating Or Milling (AREA)
US96805A 1969-12-15 1970-12-10 Method for granule pulverization Expired - Lifetime US3658259A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1857669A CH503520A (de) 1969-12-15 1969-12-15 Verfahren zum Vermahlen von körnigen Materialien, insbesondere von Kunststoffgranulaten, bei tiefen Temperaturen

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Publication Number Publication Date
US3658259A true US3658259A (en) 1972-04-25

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US (1) US3658259A (fr)
CA (1) CA918623A (fr)
CH (1) CH503520A (fr)
FR (1) FR2073732A5 (fr)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3739991A (en) * 1970-10-05 1973-06-19 Kloeckner Humboldt Deutz Ag Vibrating mill
US3771729A (en) * 1971-06-17 1973-11-13 Air Prod & Chem Cryogenic comminution system
US3785575A (en) * 1970-11-21 1974-01-15 Kloeckner Humboldt Deutz Ag Vibrating mill with introduction of refrigerants into the solid material being ground in the grinding chamber
US3897010A (en) * 1971-07-02 1975-07-29 Linde Ag Method of and apparatus for the milling of granular materials
US4112040A (en) * 1976-09-07 1978-09-05 Norman Orentreich Method of making fibers containing hair particles
US4846408A (en) * 1988-01-21 1989-07-11 Gentex Corporation Method for making a friction material
US4863106A (en) * 1988-10-13 1989-09-05 Tde, Inc. Process for low temperature comminution of scrap tires
US5704104A (en) * 1995-12-27 1998-01-06 Bacon; Forrest C. Method and machine for recycling discarded carpets
WO1999036179A1 (fr) * 1997-12-23 1999-07-22 Polymer Processing Broyeuse verticale
US6203405B1 (en) 1998-06-30 2001-03-20 Idaho Powder Products, Llc Method for using recycled aluminum oxide ceramics in industrial applications
US6360547B1 (en) 2000-01-07 2002-03-26 Crumbrubber Technology Co., Inc. Method and apparatus for cooling air to cryogenic temperatures for recycling processes
US20140021275A1 (en) * 2011-03-21 2014-01-23 Roland Nied Operating Method For A Jet Mill Plant And Jet Mill Plant
US9180463B1 (en) * 2014-08-29 2015-11-10 Joseph R. Fitzgerald Method for fractionation of dry material using accelerators
US20160263032A1 (en) * 2013-11-26 2016-09-15 Grunenthal Gmbh Preparation of a powdery pharmaceutical composition by means of cryo-milling
CN106476166A (zh) * 2015-08-27 2017-03-08 约瑟夫·菲希尔 低温碾磨装置和方法
US10300141B2 (en) 2010-09-02 2019-05-28 Grünenthal GmbH Tamper resistant dosage form comprising inorganic salt
US10335373B2 (en) 2012-04-18 2019-07-02 Grunenthal Gmbh Tamper resistant and dose-dumping resistant pharmaceutical dosage form
US10369109B2 (en) 2002-06-17 2019-08-06 Grünenthal GmbH Abuse-proofed dosage form
US10493033B2 (en) 2009-07-22 2019-12-03 Grünenthal GmbH Oxidation-stabilized tamper-resistant dosage form
US10624862B2 (en) 2013-07-12 2020-04-21 Grünenthal GmbH Tamper-resistant dosage form containing ethylene-vinyl acetate polymer
US10675278B2 (en) 2005-02-04 2020-06-09 Grünenthal GmbH Crush resistant delayed-release dosage forms
US10695297B2 (en) 2011-07-29 2020-06-30 Grünenthal GmbH Tamper-resistant tablet providing immediate drug release
US10729658B2 (en) 2005-02-04 2020-08-04 Grünenthal GmbH Process for the production of an abuse-proofed dosage form
US10842750B2 (en) 2015-09-10 2020-11-24 Grünenthal GmbH Protecting oral overdose with abuse deterrent immediate release formulations
US10864164B2 (en) 2011-07-29 2020-12-15 Grünenthal GmbH Tamper-resistant tablet providing immediate drug release
US11224576B2 (en) 2003-12-24 2022-01-18 Grünenthal GmbH Process for the production of an abuse-proofed dosage form
US11844865B2 (en) 2004-07-01 2023-12-19 Grünenthal GmbH Abuse-proofed oral dosage form
WO2024162847A1 (fr) 2023-02-03 2024-08-08 Atlantis Rubber Powders B.V. Procédé de modification de bitume

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1247008B (it) * 1991-04-24 1994-12-12 Pro Co Gen Progettazioni E Cos Procedimento ed impianto per criodistruzione dei rifiuti solidi urbani

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2400382A (en) * 1943-07-29 1946-05-14 Gerald D Arnold Closed hammer mill circuits
US2770543A (en) * 1950-11-24 1956-11-13 Gerald D Arnold Recirculating convection current cooler and method
US2879005A (en) * 1954-12-29 1959-03-24 Melvin Sobel Method of refining scrap plastic and apparatus therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2400382A (en) * 1943-07-29 1946-05-14 Gerald D Arnold Closed hammer mill circuits
US2770543A (en) * 1950-11-24 1956-11-13 Gerald D Arnold Recirculating convection current cooler and method
US2879005A (en) * 1954-12-29 1959-03-24 Melvin Sobel Method of refining scrap plastic and apparatus therefor

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3739991A (en) * 1970-10-05 1973-06-19 Kloeckner Humboldt Deutz Ag Vibrating mill
US3785575A (en) * 1970-11-21 1974-01-15 Kloeckner Humboldt Deutz Ag Vibrating mill with introduction of refrigerants into the solid material being ground in the grinding chamber
US3771729A (en) * 1971-06-17 1973-11-13 Air Prod & Chem Cryogenic comminution system
US3897010A (en) * 1971-07-02 1975-07-29 Linde Ag Method of and apparatus for the milling of granular materials
US4112040A (en) * 1976-09-07 1978-09-05 Norman Orentreich Method of making fibers containing hair particles
US4846408A (en) * 1988-01-21 1989-07-11 Gentex Corporation Method for making a friction material
US4863106A (en) * 1988-10-13 1989-09-05 Tde, Inc. Process for low temperature comminution of scrap tires
US5704104A (en) * 1995-12-27 1998-01-06 Bacon; Forrest C. Method and machine for recycling discarded carpets
WO1999036179A1 (fr) * 1997-12-23 1999-07-22 Polymer Processing Broyeuse verticale
BE1011835A3 (nl) * 1997-12-23 2000-02-01 Polymer Processing Res Inst Vermaaltoreninrichting.
US6203405B1 (en) 1998-06-30 2001-03-20 Idaho Powder Products, Llc Method for using recycled aluminum oxide ceramics in industrial applications
US6360547B1 (en) 2000-01-07 2002-03-26 Crumbrubber Technology Co., Inc. Method and apparatus for cooling air to cryogenic temperatures for recycling processes
US10369109B2 (en) 2002-06-17 2019-08-06 Grünenthal GmbH Abuse-proofed dosage form
US11224576B2 (en) 2003-12-24 2022-01-18 Grünenthal GmbH Process for the production of an abuse-proofed dosage form
US11844865B2 (en) 2004-07-01 2023-12-19 Grünenthal GmbH Abuse-proofed oral dosage form
US10675278B2 (en) 2005-02-04 2020-06-09 Grünenthal GmbH Crush resistant delayed-release dosage forms
US10729658B2 (en) 2005-02-04 2020-08-04 Grünenthal GmbH Process for the production of an abuse-proofed dosage form
US10493033B2 (en) 2009-07-22 2019-12-03 Grünenthal GmbH Oxidation-stabilized tamper-resistant dosage form
US10300141B2 (en) 2010-09-02 2019-05-28 Grünenthal GmbH Tamper resistant dosage form comprising inorganic salt
US20140021275A1 (en) * 2011-03-21 2014-01-23 Roland Nied Operating Method For A Jet Mill Plant And Jet Mill Plant
US10695297B2 (en) 2011-07-29 2020-06-30 Grünenthal GmbH Tamper-resistant tablet providing immediate drug release
US10864164B2 (en) 2011-07-29 2020-12-15 Grünenthal GmbH Tamper-resistant tablet providing immediate drug release
US10335373B2 (en) 2012-04-18 2019-07-02 Grunenthal Gmbh Tamper resistant and dose-dumping resistant pharmaceutical dosage form
US10624862B2 (en) 2013-07-12 2020-04-21 Grünenthal GmbH Tamper-resistant dosage form containing ethylene-vinyl acetate polymer
US20160263032A1 (en) * 2013-11-26 2016-09-15 Grunenthal Gmbh Preparation of a powdery pharmaceutical composition by means of cryo-milling
US10449547B2 (en) * 2013-11-26 2019-10-22 Grünenthal GmbH Preparation of a powdery pharmaceutical composition by means of cryo-milling
US9968936B1 (en) 2014-08-29 2018-05-15 Shockwave Abf Llc System and method for dry material fractionation using accelerators
US9180463B1 (en) * 2014-08-29 2015-11-10 Joseph R. Fitzgerald Method for fractionation of dry material using accelerators
CN106476166A (zh) * 2015-08-27 2017-03-08 约瑟夫·菲希尔 低温碾磨装置和方法
CN106476166B (zh) * 2015-08-27 2019-04-09 约瑟夫·菲希尔 低温碾磨装置和方法
US10842750B2 (en) 2015-09-10 2020-11-24 Grünenthal GmbH Protecting oral overdose with abuse deterrent immediate release formulations
WO2024162847A1 (fr) 2023-02-03 2024-08-08 Atlantis Rubber Powders B.V. Procédé de modification de bitume
NL2034086B1 (en) * 2023-02-03 2024-08-23 Atlantis Rubber Powders B V A method for the modification of bitumen

Also Published As

Publication number Publication date
DE2061184A1 (de) 1971-07-15
CH503520A (de) 1971-02-28
FR2073732A5 (fr) 1971-10-01
CA918623A (en) 1973-01-09

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