CA2120659A1 - Process for the production of fine granules - Google Patents

Process for the production of fine granules

Info

Publication number
CA2120659A1
CA2120659A1 CA002120659A CA2120659A CA2120659A1 CA 2120659 A1 CA2120659 A1 CA 2120659A1 CA 002120659 A CA002120659 A CA 002120659A CA 2120659 A CA2120659 A CA 2120659A CA 2120659 A1 CA2120659 A1 CA 2120659A1
Authority
CA
Canada
Prior art keywords
solvent
product melt
process according
melt
speed mixer
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.)
Abandoned
Application number
CA002120659A
Other languages
French (fr)
Inventor
Ricardo Schneeberger
Hans Horisberger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF Schweiz AG
Original Assignee
Ciba Geigy AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Ciba Geigy AG filed Critical Ciba Geigy AG
Publication of CA2120659A1 publication Critical patent/CA2120659A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/10Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic in stationary drums or troughs, provided with kneading or mixing appliances
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/003Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic followed by coating of the granules

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Glanulating (AREA)
  • Medicinal Preparation (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

Process for the production of fine granules Abstract In a process for the production of fine granules, a product melt (M) from a melt tank (2) is preferably supercooled, and then metered or sprayed into a high-speed mixer (5) and there brought into contact with dry powder, powder mixtures or also with centrifuged and then washed crystallisate (P) from a silo (6). During that operation, granules are formed by crystallisation, which are discharged from the high-speed mixer (5), subsequently dried and/or cooled in a drier (8), for example a moving bed drier or a fluidised bed drier, and then removed from the drier (8). Prior to cooling, the product melt (M) is mixed with a solvent (S), as a result of which its viscosity is greatly reduced and its wetting capacity in respect of the powder, the crystallisate or the powder mixtures (P) is substantially increased. The product melt/solvent mixture is then supercooled preferably to within the metastable range of the solubility curve so that very rapid crystallisation commences in the high-speed mixer (5). During that operation, the temperature of the product melt/-solvent mixture is so regulated that the mixture does not boil at the spray outlet (20) in the high-speed mixer (5).

(Fig.)

Description

21206~9 -' Process for the production of fine granules The invention relates to a process for the production of fine granules in accordance with the preamble of patent claim 1.

Various processes for the production of granules are known. US-A-4 578 021 describes a granulating process in which a supercooled melt provided with seed crystals is pressed through openings in a perforated hollow roller in which a rotating pressure roller is provided. The pressed-out drops fall onto a cooling belt and can there solidify or crystal-lise out. The granules that can be obtained by that process are of a relatively large size which is determined by the dimensions of the openings in the hollow roller. -~`

In another known process for the production of fine granules, dry powder, powder .
mixtures or also centrifuged and then washed crystallisate is/are mixed with product melt in a high-speed mixer. The granules formed by crystallisation during that operation are discharged from the high-speed mixer and then dried andlor cooled in a drier, for example a moving bed drier or a fluidised bed drier. Although that process is able to yield fine, low-dust gramlles, the granules are in many cases not abrasion-resistant. In addition, the application of the process is limited. In particular, in many cases it has hitherto been impossible to use that process to granulate products having high melting points or having high viscosities of the product melt, since the product melt does not adequately wet the powder, or the powder mixture or the crystallisate, in the high-speed mixer. Owing to the long crystallisation time, the product melt often does not crystallise completely, which leads to incrustation of the mixer and to lumps which may clog the pipes.

The problem of the invention is accordingly to provide a process for the production of fine granules by means of which substantially dust-free, stable, completely crystallised granules or agglomerates can be produced. It is also to be possible to use the process in the case of products having high melting points andlor having high viscosities of the product melt. The process is to permit produc~s of mixtures of any number of components tO be - `
granulated in small particle siæs.

~ :~` 2120659 Those problems are solved according to the invention by a process that comprises the process steps listed in the second part of patent claim 1. In the process according to the invention for the production of fine granules a product melt from a melt tank is super-cooled and then metered or sprayed into a high-speed mixer and there brought into contact with dry powder, powder mixtures or also with centrifuged and then washed crystallisate from a silo. During that operation, granules are formed by crystallisation, which are discharged from the high-speed mixer, subsequently dried and/or cooled in a drier, for example a moving bed drier or a fluidised bed drier, and then removed from the drier.
Prior to cooling, the product melt is mixed with a solvent, as a result of which its viscosity is greatly reduced and its wetting capacity in respect of the powder, the crystallisate or the powder mixtures is substantially increased. The product melt/solvent mixture is then supercooled preferably to within the metastable range of the solubility curve so that rapid crystallisation commences in the high-speed mixer. During that operation, the temperature of the product meltJsolvent mixture is so regulated that the mixture does not boil at the spray outlet in the high-speed mixer. The viscosity of the product melt is thus markedly reduced and the wetting capacity of the product melt is greatly improved. Crystallisation takes place very rapidly in the high-speed mixer and incrustation and lumps are avoided.
The dependent patent claims relate to preferred process variants.

The process according to the invention is explained in more detail hereinafter with refer-ence to the single Pigure which shows diagrammatically a granuladon system for implem-enting the process according to the invention.

The granuladon system is indicated as a whole by the reference numeral 1. It comprises a melt tank 2 from which a product melt M is conveyed by way of a pipeline 3 to a cooler 4 by means of a pump 18. The product melt M is supercooled in the cooler. From the cooler it passes by way of a pipeline 23 to a high-speed mixer 5. Such a mixer is described, for example, in company brochure No. wd 10.84 Rec.-d-26.3000 M of Gebruder Lodige Maschinenbau-GmbH, Elsener Str. 7-9, Postfach 2050, D-4790 Paderborn. The product melt M is metered or finely sprayed into the high-speed mixer 5 by means of spray nozzles 20 or distributing tubes and, during that operation, comes into contact with a powder P, a powder mixture or with a crystallisate that has been centrifuged and then washed. The powder or powder mixture or crystallisate is stored in a powder silo 6. An amount weighed out using a weighing device 7 is introduced into the high-speed mixer by way of a pipeline 22. In the mixer 5, the atomised product melt droplets settle on the -` 2120~5~

powder or the crystallisate which acts like a crystallisation seed and generally induces rapid crystallisation. The granu1es formed are conveyed by way of a pipeline 24 to a drier 8, for example a moving bed drier or a fluidised bed drier, and are there dried and/or cooled. The dried and/or cooled granules are finally removed from the drier 8 by way of a pipeline 9.

Before the product melt M is supercooled in the cooler 4, it is mixed with a solvent S
which, by means of a pump 19, is conveyed by way of a pipeline 21 out of a solvent tank 16 and to a mixing device 17. As a result of mixing the product melt M with the solvent S, the viscosity of the product melt is greatly reduced, for example from the range of approximately 1000 to over 100 000 mPas to the range of approximately 30 to 1500 mPas. At the same time, the wetting capacity of the product melt M in respect of the powder, crystallisate or powder mixture is substantially increased. The product melt/-solvent mixture is supercooled in the cooler 4, preferably to within the metastable range of the solubility curve. It is thus ensured that the atomised product melt/solvent mixture crys-tallises very rapidly in the high-speed mixer S when it comes into contact with the powder, powder mixture or crystallisate P. The temperature of the product melt/solvent mixture is preferably so regulated that the mixture does not boil at the spray outlet 20. It will be understood that the pipeline 23 between the cooler 4 and the high-speed mixer 5 is for that purpose constructed to be heatable in a regulated manner. For example, the pipeline 23 is a double-walled pipe in which circulates a heating liquid, the temperature of which can be adjusted.

In the mixing device 17, product melt M is mixed continuously with the solvent S. In order to supersaturate the solution, the product melt/solvent mixture is supercooled.
Starting from the solubility equilibrium temperature (at which there exists a saturated solution) the product meltlsolvent mixture is supercooled by up to 70C. The degree of supersaturation increases with the degree of supercooling.
.,~
In the regulation of ~he temperature of the supersaturated solution, care is preferably taken that the ~emperature of the supersaturated solution is kept lower than the boiling tempera-ture of the solvent. If the product melt/solvent mixture is mixed and transported under elevated pressure the temperature can be higher, and it is also found that smaller amounts of solvent S will suffice. A superpressure of from approximately 0 bar to approximately 5 bar is preferably set.

'4. ' In order to prevent the evaporation of solvent from the product melt/solvent mixture and -the commencement of crystallisation, which may cause the pipes to become clogged, the mixing of the solvent S with the product melt is carried out in a closed system, care being taken that the system is free of pockets of gas.

It is especially advantageous if the mixing device 17, in which the product melt M is mixed with the solvent S, is a static mixer. Such static mixers are widely used in chemical synthesis and are described, for example, in an article by Adolf Heierle "Statische Mischer-Warmeaustauscher", in chemie-anlagen + verfahren 7/89. With regard to the process according to the invention, the advantages of a static mixer result especially from the fact that the system is free of pockets of gas. In addition, it has no moving parts, is easy to clean and is inexpensive. It would, however, also be possible to use a rotor-stator mixer system instead of a static mixer.

The obtainable size of the granules produced can be altered by varying the ratio of the amounts of the solvent S and the product melt. The quantitative ratio is preferably so adjusted that granule sizes of from approximately 0.15 mm to approximately I mm, with a range of fluctuation of up to approximately i 0.3 mm, are obtained.

In the process according to the invcntion for the production of fine granules, polar solvents, such as, for example, methanol, isopropanol or water, are preferably used. The solvent S is recovered when the granules are dried in the drier 8, which, apart from comprising an inert gas circuit 12 for providing inert gas heated in a heater 11, also comprises a filter 13, a condenser 14 and a solvent separator 1~ by means of which the solvent S evaporated off in the drier can be recovered in known manner.

By mixing the product melt with a solvent, the viscosity of the product melt is greatly reduced, as a result of which many highly viscous product melts can also be granulated in a high-speed mixer. In addidon, the mixing of the product melt with the solvent also increases to a marked degree the wetting capacity of the atomised product melt in respect of the powder, powder mixture or crystallisate, as a result of which the crystallisation time is greatly reduced. The process according to the invention is accordingly also suitable for the granulation of product melts of antioxidants, stabilisers or light-protective agents, which, in the unmixed state, usually have too high a viscosity. The supercooling of the product melt/solvent mixture ensures spontaneous crystallisation in the high-speed mixer.
As a result, incrustation of the walls of the high-speed mixer is prevented, and the ~:- 2120~9 formation of lumps, which could clog the pipelines, is obviated. The temperature control -of the process according to the invention is such that undesired crystallisation in the pipe-lines or in the cooler is largely excluded.

The process according to the invention can be used for powders comprising one or more ~ -components. That is to say, apart from pure substances, it is also possible to granulate powder mixtures in fine particle sizes. The components of the powder rluxtures may be pre-mixed or may be mixed directly in the high-speed mixer in an appropriately lengthen- -ed mixing part. For example, one of the components is provided as the product melt which is mixed with the solvent before it is preferably supercooled and metered or sprayed into ; ~ ~
the high-speed mixer. ~ i ~' - ~;, ;", . ' '':. ~: ~' .'

Claims (11)

1. A process for the production of fine granules, in which a product melt (M) from a melt tank (2) is preferably supercooled, and then metered or sprayed into a high-speed mixer (5) and brought into contact with dry powder, powder mixtures or also with centri-fuged and then washed crystallisate (P) from a silo (6), crystallisation giving rise to granules which are discharged from the high-speed mixer (5), subsequently dried and/or cooled in a drier (8), for example a moving bed drier or a fluidised bed drier, and then removed from the drier (8), in which process the product melt (M) is mixed with a solvent (S) prior to cooling, as a result of which its viscosity is greatly reduced and its wetting capacity in respect of the powder, the crystallisate or the powder mixtures (P) is substantially increased, the product melt/solvent mixture is supercooled preferably to within the metastable range of the solubility curve so that rapid crystallisation commences in the high-speed mixer (5), and the temperature of the product melt/solvent mixture is so regulated that the mixture does not boil at the spray outlet (20) in the high-speed mixer (5).
2. A process according to claim 1, wherein the product melt/solvent mixture is produced on-line in the form of a supersaturated solution by supercooling, the product melt/solvent mixture being supercooled by up to approximately 70°C starting from the solubility equi-librium temperature.
3. A process according to claim 2, wherein the temperature of the supersaturated solution is kept lower than the boiling temperature of the solvent.
4. A process according to any one of the preceding claims, wherein the mixing of the product melt (M) and the solvent (S) is carried out under elevated pressure, a super-pressure of from approximately 0 bar to approximately 5 bar being selected.
5. A process according to any one of the preceding claims, wherein the mixing of the product melt (M) and the solvent (S) is carried out in a closed system without pockets of gas.
6. A process according to any one of the preceding claims, wherein the mixing of the product melt (M) and the solvent (S) is carried out in a static mixer (5).
7. A process according to any one of the preceding claims, wherein a polar solvent, for example methanol, isopropanol or water, is used as the solvent (S).
8. A process according to any one of the preceding claims, wherein the size of the granules is varied by varying the ratio of the amounts of the solvent (S) and the product melt (M).
9. A process according to claim 8, wherein the ratio of the amounts of the solvent (S) and the product melt (M) is so adjusted that the size of the granules is from approximately 0.15 mm to approximately 1 mm.
10. A process according to any one of the preceding claims, wherein the product melt (M) is an antioxidant, a stabiliser or a light-protective agent.
11. A process according to any one of the preceding claims, wherein, by mixing the product melt (M) with the solvent (S), the viscosity of the product melt is reduced from the range of approximately 1000 to over 100 000 mPas to the range of approximately 30 to 1500 mPas, and its wetting capacity in respect of the powder, the crystallisate or the powder mixtures is substantially increased.
CA002120659A 1993-04-08 1994-04-06 Process for the production of fine granules Abandoned CA2120659A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP93810253.0 1993-04-08
EP93810253A EP0619137B1 (en) 1993-04-08 1993-04-08 Process to prepare finely granulated material

Publications (1)

Publication Number Publication Date
CA2120659A1 true CA2120659A1 (en) 1994-10-09

Family

ID=8214947

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002120659A Abandoned CA2120659A1 (en) 1993-04-08 1994-04-06 Process for the production of fine granules

Country Status (9)

Country Link
EP (1) EP0619137B1 (en)
JP (1) JPH07132220A (en)
KR (1) KR100327679B1 (en)
CN (1) CN1074940C (en)
AU (1) AU675288B2 (en)
CA (1) CA2120659A1 (en)
DE (1) DE59308701D1 (en)
ES (1) ES2118212T3 (en)
SK (1) SK280446B6 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5979165A (en) * 1995-11-20 1999-11-09 Good Humor-Breyers Ice Cream Process for supercooling

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL113562A (en) * 1995-05-01 1999-08-17 Bromine Compounds Ltd Process for the production of finely granulated solid chemical compounds
DE19541242A1 (en) 1995-11-06 1997-05-07 Hoechst Ag Storage-stable plastic additives
GB9625415D0 (en) * 1996-12-06 1997-01-22 Agglomeration Technology Ltd Method of coating particulate matter
JP3962703B2 (en) * 2003-05-09 2007-08-22 東都化成株式会社 Method for crystallizing organic oligomer

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1592512B2 (en) * 1966-09-12 1973-02-15 Solvay & Cie,Brüssel PROCESS FOR THE MANUFACTURE OF GRANULATED FERRICHLORIDE HEXAHYDRATE
DE1771558B1 (en) * 1968-06-08 1970-12-03 Quarzwerke Gmbh Process for coating fine-grain bulk material, in particular quartz sand and quartz powder
US4231924A (en) * 1976-09-23 1980-11-04 Abbott Laboratories 4-N-Acylfortimicin B derivatives and the chemical conversion of fortimicin B to fortimicin A
US4213924A (en) * 1978-06-19 1980-07-22 Tennessee Valley Authority Granulation and coating by improved method of heat removal
US4578021A (en) * 1983-11-01 1986-03-25 Santrade Ltd. Apparatus for the production of granules from two-phase mixtures
US4540546A (en) * 1983-12-06 1985-09-10 Northeastern University Method for rapid solidification processing of multiphase alloys having large liquidus-solidus temperature intervals
DE3635313A1 (en) * 1986-10-17 1988-04-28 Bayer Ag METHOD FOR PRODUCING GRANULES
ES2022466B3 (en) * 1987-01-20 1991-12-01 Dow Chemical Co GRANULATED BIPHENYL PRODUCTION
US5006284A (en) * 1989-06-14 1991-04-09 Ciba-Geigy Corporation Granules of alkyl esters containing hydroxyphenyl groups

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5979165A (en) * 1995-11-20 1999-11-09 Good Humor-Breyers Ice Cream Process for supercooling

Also Published As

Publication number Publication date
ES2118212T3 (en) 1998-09-16
AU5922394A (en) 1994-10-13
EP0619137B1 (en) 1998-06-17
CN1093300A (en) 1994-10-12
CN1074940C (en) 2001-11-21
AU675288B2 (en) 1997-01-30
DE59308701D1 (en) 1998-07-23
SK280446B6 (en) 2000-02-14
EP0619137A1 (en) 1994-10-12
SK39294A3 (en) 1994-11-09
JPH07132220A (en) 1995-05-23
KR100327679B1 (en) 2002-06-20

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