FR2561133A1 - PROCESS FOR COATING ACTIVE MATERIAL - Google Patents

Abstract

THIS INVENTION CONCERNS A PROCESS FOR COATING ACTIVE MATERIALS WITH QUICK DISSOLUTION OF WHICH AN APPROACH TO REDUCE THE RELEASE SPEED IN A GIVEN MEDIUM. THE COATING IS CARRIED OUT BY COMPACTION AT ROOM TEMPERATURE OF A MIXTURE OF SOLID PARTICLES OF ACTIVE MATERIAL AND SOLID PARTICLES OF A PSEUDOPLASTIC MATERIAL. BY PSEUDOPLASTIC BEHAVIOR WE MEAN THE FACULTY OF A MATERIAL TO FLUATE AND TO AGGLOMERATE UNDER THE EFFECT OF PRESSURE. AMONG THE COATINGS, OIL PRODUCTS RICH IN ASPHALTEN AND POLYMERIC MATERIALS. THIS PROCESS IS ESPECIALLY SUITABLE FOR COATING INORGANIC FERTILIZERS, PHYTOSANITARY PRODUCTS AND PRODUCTS USED FOR TREATING INDUSTRIAL AND URBAN EFFLUENTS.

Description

This invention relates to a process for coating active ingredients with

  rapid dissolution of which we seek to reduce the speed of release in a given medium. It is particularly suitable for the manufacture of inorganic slow release fertilizers. Only 50 to 80% of the nitrogen fertilizer applied in

  the soil is used by the plant. One of the factors

  The sands of this imperfect assimilation is the great solubility of nitrogenous fertilizers in water, which leads to a considerable loss of nitrogen by leaching. The fertilizer thus leached is not only a loss for agriculture and therefore a major waste but at the same time it contributes to the eutrophication of groundwater.

and streams.

  Slow-release fertilizers, also known as late-release fertilizers, are fertilizer products capable of regulating the release of their nutrients and ensuring the best match between the needs of the plant and the

  release of nutrients into the soil.

  The delay effect is obtained by external coating or

  coating the particles of active material in the mass.

  External coating consists of forming a film

  wrapping around the particle of active material. The in-

  The massing is carried out by intimate mixing of the active ingredient with the coating agent. Each particle of matter

  active is isolated or dissolved in an insoluble matrix.

  In the case of fertilizers, the outer coating should form a thick and homogeneous film around each particle of fertilizer. This film filters the exchanges between the inside and the outside of the particle, it slows down the release of the fertilizing ions. This film must be so solid that it does not burst in the soil under the effect of the osmotic pressure. Training

  such a coating is a delicate operation.

  The process of CHISSOASAHI FERT, described in the patent

  French 2,255,962, realizes the external coating by puLveri--

  an organic solution of a thermoplastic resin

on the fertilizer granules.

  The process requires the use of large amounts of organic solvents. Evaporation and recycling of these solvents increases the process. IT is a source of losses

  solvents and considerable energy costs.

  The coating processes in the mass have a common

  The implementation of the coating at high temperature.

  Thus, according to US Pat. No. 3,219,433, the coating is carried out by molten bitumen either by dipping or by

  spraying or spraying molten bitumen on fertilizer

health.

  All these processes therefore prohibit the use of

  thermosensitive active substances. The decomposition temperature

  position of inorganic fertilizers varies between about 150 and 200 C. In their case there is therefore risk of decomposition

during the coating.

  The object of the present invention is to mitigate these

  conveniences and realize the coating in the mass of the active ingredients by a simple process that can be applied

  to thermosensitive active substances.

  This process for coating rapidly dissolving active substances whose release rate is to be reduced is characterized in that the coating is carried out by compacting a mixture of solid particles of active material and solid particles of 'a

pseudoplastic matter.

  By pseudo-plastic behavior we mean the faculty of a material to flow and agglomerate under

the effect of Pressure.

  The compacting temperature is between 0 and 50 C and preferably between 15 and 30 C. The pressure of

  compacting is between 0.1 and 100 bar, preferably

between 10 and 50 bar.

  Respective granulometries of the active ingredient

  and coating it, the weight ratio of active / enro-

  and the nature of the coating are the essential characteristics that determine the quality of the

obtained by the coating.

  If the average diameter of the active material particles and the coating particles have very similar or identical values, the mixture obtained is coarse and access to the particles of active material in the coated product remains very easy. The release of the active ingredient will be rapid. At the other end, if the ratio of the average diameter

  particles of active material on the particles of enro-

  bant is about 10, there is a flow of the fines of the coating between the coarse particles of active material until the destabilization of the mixture with separation of two solid phases. Finally, the particles of active material form an uncoated continuous phase with easy access. The release of the active ingredient is

still fast.

  On the other hand, if the ratio of the average diameter of

  cules of active material on the coating particles is between 2 and 8 and preferably between 3 and 4, the mixture is stable a good dispersion of the material is obtained

active.

  The size of the particles of active material can. be between 10 and 1500 microns and preferably between and 300 microns, that of the coating particles between

  1 and 500 microns and preferably between 30 and 100 microns.

  The coated active ingredient is in the form of pellets, tablets, granules, corks,

  sticks ranging in size from 1 to 40 mm and

between 2 and 6 mm.

  The mixes contain between 20 and 70% by weight, preferably between 40 and 50% of coating and between 30 and 80%

  preferably between 50 and 60% of active ingredient.

  The process is suitable for coating fast-dissolving active substances whose release rate is to be reduced, provided that they are

  are in the form of solids that can be ground.

  All inorganic fertilizers or their mixtures

  for this process, such as, for example, potassium or ammonium nitrate, soluble phosphates or

ammonium chloride.

  Among the active ingredients one can also mention phytosanitary products such as fungicides, insecticides or herbicides and products used in the treatment of industrial or urban effluents such as bactericides, neutralizers or complexants. The suitable solvents are the grinding solids

  pseudoplastic behavior. By pseudoplastic behavior

  tick we hear the facuLty of a matter of flowing and

  to agglomerate under the effect of pressure.

  Among the coating agents, mention may be made of asphaltene-rich petroleum products such as the asphalts obtained

  by deasphalting the residues under vacuum, atmospheric residues

  or residues of heavy crudes. As solvents

  deasphalting, the paraffinic hydrocarbons

  from C3 to about C7. The best results are

  obtained by asphalts extracted with butane or pentane.

  Other solid products, such as

  They are also suitable as enrobers. Coating can be an interesting use for residues

polymer.

  It may be useful to incorporate inor-

  such as talc, bentonite or dried clay

  to avoid the agglomeration of the mixes. There is also

  organic products such as anti-caking agents

for this purpose.

  Coating does not change the chemical nature of

  active ingredients. In the case of fertilizers the nutritional value

  tive is kept. Simply The effect of the fertilizer is delayed in time. The fertilizer is applied on the surface or inside the soil and under normal conditions of agricultural use the active ingredient is released into

3-4 months.

  The coating process generally has three

  main steps grinding, mixing and compacting.

  For the grinding of the active ingredient and the coating one can use all types of grinders known as

  ball or hammer mills.

  it is possible to proceed to a separate grinding of the

  sometimes, thanks to the difference in the hardness of the active ingredient and the coating, the mixed grinding

  gives mixtures of suitable particle size ratio.

  If the products have been ground together the mixing step

becomes superfluous.

  In case of separate grinding it is necessary to mix

  The constituents before compact-age. All types of

  usually used to mix particles

  The solids or powders are suitable, such as kneaders with drum, screw or counter-helicoidal or a dough with a worm The time required to achieve a homogeneous mixture can vary between a few seconds to a few minutes depending on the nature of the products and the type of mixer. It is possible to operate continuously or discontinuously. The most important operation is compaction. In general, it is carried out by pressing or extrusion. Depending on the method of compaction chosen, the finished product is in the form of pellets, tablets, granules, corks, sticks, etc., the size of which varies between 1.

  and about 40 mm and preferably between 2 and 6 mm.

  Rotary or eccentric presses (KILIAN) provide tablets. Roll presses (ALEXANDERWERK) provide plates that require

  additional crushing, followed by granulometric sorting.

  The sorting is carried out by a sieve or possibly using

of a cyclone.

  According to a particularly advantageous implementation of the process, mixing and compacting are carried out by

  an extruder. The extruder is fed with crushed product.

  It is preferable to use in this case a mixed mill

  for the coating and the active ingredient.

  Grinding and compacting operations can be carried out between 0 and 50 ° C but preferably

  Work at room temperature between 15 and 30 C.

  By way of nonlimiting example, the attached single figure is shown in the diagram of an installation according to the invention. The starting materials arrive through the active material hopper (1) and the coating hopper (2). They undergo separate milling in the mill (3) which sends the milled product to the hopper of the milled active ingredient (4). ) or ground coating hopper (5). Through the feed and mixing hopper (6) The mixture active and coating material

  arrives on a worm (7) which ensures a final

  age and predensification. This auger feeds the cypress press (8). The formed plates are crushed by a crusher (9) and then crushed by the mill (10). The product is sent to a separator screen (11) with three compartments. The coarse particles are returned to the crusher (9). The finer ones return to the feed hopper (6). The product of the desired particle size is sent to a bagger (12) then to

storage (13).

EXAMPLE

  The separate grinding of a deasphalting asphalt is carried out

  pentane and previously dried ammonium nitrate.

  The fraction of fertilizer between 400 and 625 microns and an asphalt fraction between 1 and 100 microns are collected by sieving. 12.5 g of asphalt and 12.5 g are mixed

  ammonium nitrate. The mixture is homogenized by maLaxa-

  using a roller dynamometer. When the mixture is

  homogeneous, the pastiLLage is carried out by a hydraulic press.

  Laboratory Lique. We work under a pressure of bars for 30 seconds, the decompression time being

  20 seconds. 4 pastiales of about 6 g are obtained.

  To compare the leaching resistance of fertilizer with

  when tested with an ammonium nitrate control, a leaching test is carried out. After filling two cups, one with a measured quantity of coated fertilizer, the other with pure ammonium nitrate of the same particle size, ml / hour of demineralized water is sent through the cups.

during 3h45 minutes.

  Leached fertilizer is collected and weighed after evaporation

some water.

  The percentage of fertilizer retained (Xr) is calculated by the formula: -] Xr ix 100 m1 m = mass Leached m. = initial mass The retained fertilizer percentage (Xr) is 40.28% for the coated fertilizer and 2.3% for the pure ammonium nitrate.

Claims (14)

  1 - A process for coating active substances capable of rapidly dissolving, the aim of which is to reduce the release rate, characterized in that the coating is made by compacting a mixture of solid particles of active material and solid particles. of a pseudoplastic material.   2 - Process according to the claim characterized in that the compaction temperature is between 0 and    C and preferably between 15 and 30 C.   3- Process according to claims 1 and 2 characterized in   that the compaction pressure varies between 0.1 and   bars and preferably between 10 and 50 bars.   4 - Process according to one of claims 1 to 3 caractéri-   the ratio of the average diameter of the   cules of active ingredients on the coating particles   is between 2 and 8 and preferably between 3 and 4.   - Method according to one of claims 1 to 4 characterized   in that the size of the particles of active material is between 10 and 1500 microns and preferably between 100 and 300 microns.   6 - Process according to one of claims 1 to 5 characterized   in that the size of the solid particles of   robant is between 1 and 500 microns and preferably between 30 and 100 microns.   7 - Method according to one of claims 1 to 6 characterized   in that the size of the mixes is between I and   mm and preferably between 2 and 6 mm.   8 - Process according to one of claims 1 to 7 character-   in that the mixes contain between 30% and 50% by weight, preferably between 50% and 60% by weight of   active ingredient and between 20% and 70% by weight of   this between 40 and 50% weight of coating.   9 - Process according to one of claims 1 to 8 characterized   in that the mixing is carried out by mixed grinding of   the active ingredient and coating it.   Method according to one of claims 1 to 9   risé in that compaction is achieved by pressing   of a mixture of particles of active material and enironment particles. bant. -9   II - Method according to one of claims 1 to 9 character-   characterized in that compaction is achieved by ex-   trusion of a mixture of particles of active ingredient and coating particles.   12 - Method according to one of claims 1 to 11 carac-   in that the coating is an asphalt of   splashing with paraffinic solvents.   13 - Process according to claim 12 characterized in that the deasphalting is carried out with a paraffinic solvent between C3 and C7 preferably between C4 and C5.   14 - Method according to one of claims 1 to it carac-   characterized in that the coating material is a polymeric material ricue.   15 - Process according to one of claims 1 to 14 charac-   characterized in that the active ingredient is an inorganic fertilizer   16 - Method according to one of claims 1 to 14 character-   characterized in that the active ingredient is a phytosanitary product such as a fungicide, insecticide or herbicide.   1.7 - Process according to one of claims 1 to 14,   characterized in that the active ingredient is a product used in the treatment of effluents such as   bactericidal, neutralizing or complexing agents.   18 - Mixed products obtained by the process according to one of the Claims 1 to 17. 9 sheets Company Anonymous known as ELF FRANCE