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GB2049429A - Process for preparing composite granules - Google Patents

Process for preparing composite granules Download PDF

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Publication number
GB2049429A
GB2049429A GB8012924A GB8012924A GB2049429A GB 2049429 A GB2049429 A GB 2049429A GB 8012924 A GB8012924 A GB 8012924A GB 8012924 A GB8012924 A GB 8012924A GB 2049429 A GB2049429 A GB 2049429A
Authority
GB
United Kingdom
Prior art keywords
process according
pulverulent material
granular substrate
granules
composite granules
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.)
Granted
Application number
GB8012924A
Other versions
GB2049429B (en
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.)
Borax Europe Ltd
Original Assignee
Borax Consolidated Ltd
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 Borax Consolidated Ltd filed Critical Borax Consolidated Ltd
Priority to GB8012924A priority Critical patent/GB2049429B/en
Publication of GB2049429A publication Critical patent/GB2049429A/en
Application granted granted Critical
Publication of GB2049429B publication Critical patent/GB2049429B/en
Expired legal-status Critical Current

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Classifications

    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01NPRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/26Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests in coated particulate form
    • CCHEMISTRY; METALLURGY
    • C05FERTILISERS; MANUFACTURE THEREOF
    • C05GMIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G5/00Fertilisers characterised by their form
    • C05G5/40Fertilisers incorporated into a matrix

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Pest Control & Pesticides (AREA)
  • General Health & Medical Sciences (AREA)
  • Organic Chemistry (AREA)
  • Agronomy & Crop Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Plant Pathology (AREA)
  • Toxicology (AREA)
  • Engineering & Computer Science (AREA)
  • Dentistry (AREA)
  • Wood Science & Technology (AREA)
  • Zoology (AREA)
  • Environmental Sciences (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)

Abstract

A process for preparing composite granules is disclosed which comprises mixing a granular substrate and a pulverulent material with an aqueous solution of an inorganic salt which forms a non-hygroscopic hydrated salt in the presence of the pulverulent material. The pulverulent material is thereby firmly attached to the hydrated salt crystallised on the surface of the granular substrate, and the resulting composite granules are dried. A particular application of the process is for the preparation of fertilisers, herbicides, fungicides and pesticides.

Description

SPECIFICATION Process for preparing composite granules This invention relates to a process for preparing composite granules. More particularly, this invention relates to a process for preparing composite granules whereby the adherence of a pulverulent material to granular substrates is improved. A particular application of the process of the invention is in the agricultural field and in particular in connection with fertilisers, herbicides, fungicides and pesticides. Such materials are often compounded with solid diluents such as talc or chalk in a finely divided state for the purpose of spraying on crops or on ground which has been sown.A problem which arises with the spraying or other distribution of such materials in finely divided form is that the resulting dust particles readily become airborne and hazardous to the operator and also thatthey may settle in unwanted locations, e.g. on growing crops.
Various proposals have therefore been made for the compounding of such pulverulent materials in a granular as opposed to finely divided form. Thus, granules have been made by the compacting of powdered material with or without additional inert diluents. Alternatively, the active ingredients in finely divided form have been mixed with an inert filler and water and the product has thereafter been extruded and granulated to the desired granular size.
One problem which has, however, arisen in practice with such proposals is that the granular materials have often fractured either during manufacture or during subsequent handling, thereby creating again the problem of dusting.
Accordingly, there have been alternative proposals which have involved the use of a so-called strong or fracture-resistant substrate upon which the desired active ingredient or ingredients have been coated with or without additional inert diluents also in finely divided form. Thus, coating processes have been proposed which use so-called "strong" substrates on which glues, oils or waxes had been either absorbed or adsorbed thereby producing surfaces on which the powdered active ingredient optionally together with a powdered diluent would adhere. It has, however, been found in practice that granules made by using aqueous glues need considerable periods of time for drying before they become free flowing and the use of non-aqueous adherents involved the risk of a delay in the release of active ingredient from the granule.Furthermore dusting problems have not been overcome.
We have found what we believe to be both a novel and an effective way of forming composite granules from finely divided or powdered materials. The method of the invention has been evolved from our discovery that such a pulverulent material can be firmly attached to the surface of a granular substrate by the crystallisation on the surface of certain non-hygroscopic hydrated salts which entrap the powdered material.
Thus, the present invention provides a process for preparing composite granules comprising a granular substrate and a pulverulent material which compris es contacting the granular substrate and the pulveru lent material with an aqueous solution of at least one inorganic salt which forms a non-hygroscopic hydrated salt in the presence of the pulverulent material whereby the pulverulent material is attached to the hydrated salt crystallised on the surface of the granular substrate, and drying the resulting composite granules.
According, in the process of this invention the surface of a granular substrate is coated with an.
inorganic salt or salts from an aqueous solution which form thereon such non-hygroscopic hydrated salt or salts in the presence of the pulveru lent material. The pulverulent material is thereby firmly attached to the hydrated salt or salts crystallised on the surface of the substrate granules to form the desired composite granules which are then dried.
We preferthatthe granular substrate and in particular the composite granules should have physical characteristics which enable them to be resistantto dusting and to fracturing during normal packing and storage procedures.
A preferred substrate material is for example a naturally occurring mineral such as limestone, calcite or marble; these are commercially available and economic to use in comparison with materials which have to be prepared by manufacturing techniques such as extrusion.
The substrate granules may be prepared for example by crushing and sieving the mineral and retaining the desired size fraction. The preferred particle size of the granules used in the process of the invention may range from 4,000 microns (4 BS mesh) to 250 microns (60 BS mesh). A particularly preferred size is substantially 1000 microns (16 BS mesh).
Preferred inorganic salts are alkali metal borates and mixtures thereof. In particular, those alkali metal borates which are most soluble in water are suitable for use in the process according to the invention. For example, Polybor (Trade Mark) which is disodium octaborate tetrahydrate is particularly suitable for use as the inorganic salt. The alkali metal borates are preferably heated to above 60"C in order to ensure good solubility.
According to one aspect of the present invention an inorganic salt or mixture of salts in finely divided form may be added to the other components in dry form before spraying with the inorganic salt solution.
The amount of inorganic salt used in the process of the invention depends on the particle size of the granules employed but is usually in the range of 1-20% by weight of the granules. Typically, for granules of above 1000 microns in size, an amount of inorganic salt representing substantially 2% of the weight of granules is used.
One advantage of the method of the invention is that the products are dry and suitable for packaging in a short period of time as compared with various prior proposals. A second advantage is that the active ingredient used is immediately available to the environment on which it is sited.
The process of the invention is preferably carried out in a rotating drum type of mixer, although it will be apparent that any type of conventional mixer which is capable of effecting the overall distribution of the pulverulent material on the surface of the granules may be used. We have found that a mixing time of substantially 15 minutes in a rotating drum mixer may be sufficient to prepare the product of the invention. Pulverulent material is dry mixed with the granules prior to adding the inorganic salt solution.
In order to ensure even distribution, the inorganic salt solution must be added slowly to the components preferably by spraying directly on to the materials being mixed.
it has been found to be beneficial to add a surface-active agent. The addition of up to 5% of surface-active agent based on the weight of water employed is preferred.
Any pulverulent material which is not affected by the chemicals used in the process of the invention may be caused to adhere to the granular substrate which we have defined above. In particular, as stated above, we have found that the method of the invention is particularly suited to the development of composite granules for use as herbicides fertilisers and pesticides. The active ingredient in powdered form either alone or together with one or more similar powdered solid diluents may be for example a fertiliser in finely divided form or a powdered herbicide, fungicide or pesticide. Typically, the substrate granules may be coated with an active ingredient which represents up to 10% of the weight of the substrate. In the case of a herbicide for example, the active ingredient may be present in any proportion from 1-8% of the weight of the composite granule as a whole.
The invention described in general terms above is now further described and illustrated by the follow ing examples of specific embodiments of the processes of the invention.
Example 1 150 kg of limestone granules having a particle size of about 1000 microns were mixed with 6.96 kg of Atrazine herbicide having a particle size of less than about 90 microns and 0.15 kg EMPICOL (Trade Mark) for an anionic surface active agent in a rotating drum mixer. A solution comprising 2.7 kg of POLYBOR (Trade Mark for disodium octaborate tetrahydrate) in 4.051 water at 75-80 C was sprayed on to the well mixed ingredients over a period often minutes.
Mixing was continued for 15 minutes. The resulting product comprised free flowing, non-dusting gra nules suitable for packing. No caking of the packed product was observed after storage for one week.
Example 2 The procedure followed was similar to that de scribed in Example 1 except 6.96 kg Atrazine was replaced by 6.96 kg Bromacil herbicide. A similar product to that described in Example 1 was obtained.
Example 3 1 kg of fine grade limestone granules as described in Example 1 was mixed with 36g of sodium metaborate of less than 250 microns in size, 40g of finely divided Atrazine and 1g of EMPICOL in a rotating drum mixer. A solution at750C comprising 48.29 of POLYBOR in 60g water was sprayed on to the mixed ingredients over a period of 10 minutes.
Stirring was continued for 1 hour.
The resulting product comprised discrete granules with an evenly distributed coating of herbicide, was free flowing and non-dusting.

Claims (10)

CLAIMS:
1. A process for preparing composite granules comprising a granular substrate and a pulverulent material which comprises contacting the granular substrate and the pulverulent material with an aqueous solution of at least one inorganic salt which forms a non-hygroscopic hydrated salt in the presence of the pulverulent material whereby the pulverulent material is attached to the hydrated salt crystallised on the surface of the granular substrate, and drying the resulting composite granules.
2. A process according to claim 1, wherein the inorganic salt is one or more alkali metal borates.
3. A process according to claim 2, wherein the alkali metal borate is disodium octaborate tetrahydrate.
4. A process according to any of claims 1 to 3, wherein the contacting is effected in the presence of a surface active agent.
5. A process according to any of claims 1 to 4, wherein the inorganic salt is used in a proportion of 1-20% by weight based on the weight of the granular substrate.
6. A process according to any of claims 1 to 5, wherein the granular substrate is limestone, calcite or marble.
7. A process according to any of claims 1 to 6, wherein the particle size of the granular substrate is within the range from 4,000 microns to 250 microns.
8. A process according to claim 7, wherein the particle size of the granular substrate is substantially 1000 microns.
9. A process according to any of claims 1 to 8, wherein the pulverulent material is a herbicide, fertiliser or pesticide.
10. A process for preparing composite granules substantially as herein described with reference to the specific Example.
GB8012924A 1979-04-23 1980-04-18 Process for preparing composite granules Expired GB2049429B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8012924A GB2049429B (en) 1979-04-23 1980-04-18 Process for preparing composite granules

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7914110 1979-04-23
GB8012924A GB2049429B (en) 1979-04-23 1980-04-18 Process for preparing composite granules

Publications (2)

Publication Number Publication Date
GB2049429A true GB2049429A (en) 1980-12-31
GB2049429B GB2049429B (en) 1983-01-12

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8012924A Expired GB2049429B (en) 1979-04-23 1980-04-18 Process for preparing composite granules

Country Status (1)

Country Link
GB (1) GB2049429B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0184663A1 (en) * 1984-11-21 1986-06-18 Bio-Kil Chemicals Limited The production of shaped bodies of boron compounds

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0184663A1 (en) * 1984-11-21 1986-06-18 Bio-Kil Chemicals Limited The production of shaped bodies of boron compounds

Also Published As

Publication number Publication date
GB2049429B (en) 1983-01-12

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