FR2531347A1 - PROCESS FOR PREPARING AQUEOUS DISPERSIONS NOT SEDIMENT - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR THE PRODUCTION OF AQUEOUS DISPERSIONS, WHICH DO NOT SEDIMENT. IN ACCORDANCE WITH THE INVENTION, BEFORE THE PREPARATION OF THE DISPERSION, THE STARCH AND THE CARBAMIDE EITHER SEPARATELY OR IN THE FORM OF A PREPARED MIXTURE, IN THE DISPERSION MEDIUM OR IN THE DISPERSION ALREADY CONTAINING THE SOLID PARTICLES. . THE PROCESS CAN BE ADVANTAGEALLY USED FOR THE STABILIZATION OF CHEMICAL FERTILIZER SUSPENSIONS.

Description

The present invention relates to a process for the preparation of

  aqueous dispersion which does not sediment, by dispersion of solid particles in water, which process is characterized in that prior to the preparation of the dispersion, the aqueous medium or the dispersion already containing the solid particles is distributed in starch and carbamide, either separately or under the

  form of a previously mixed product.

  It is known that soil particles that are part

  of the size range of the colloids, sediment extremely

  slowly, so that a sedimentation equilibrium is established. The particles of the suspensions, which represent the coarser order of magnitude, sediment relatively rapidly, in the case where their density is higher than that of the medium (see ERDEY- GRUZ, T SCHAY, Cs: Theoretische Physikalische Chemie, Tank 5 nyvkiad 6,

Budapest, 1964, pp. 226-233).

  In the case of both colloids and

  of the coarser order of magnitude, are present in the systems, the particles that enter

  in the field of coarsest magnitude and sedimen-

  relatively fast, outweigh the smaller particles, and can clump with them and they can eventually settle at a high speed

  as a result of what is known as ortho-coagulation

  kinetics, in a way that is absolutely not

  small particles, but which is characteristic of polydisperse systems (see Dr BUZAGH A: Praktikum

  der Kolloidik, Tank 8 nyvkiad 6, Budapest, 1962, pages 143-149).

  A large part of the industrial processes have for

  purpose of producing systems that sediment well, primarily

  in the case of the separation of substances in the solid or liquid state, as is the case, for example, in the dewatering of different sludges or in the transformation into sheets in the paper industry. another part of industrial processes, the aim is to increase the stability, to prevent sedimentation, as is the case for example in the manufacture of sludge

  drilling for the extraction of crude oil, for the manufacture

  cation of different emulsions or when the storage of

  dispersions pose as a transportation problem.

  Typical examples of what has just been said are represented by the manufacture of the suspensions of charges in the paper industry, the stabilization of

  paraffin and bitumen emulsions which can be used in different

  goals or the stabilization of plant protection agent emulsions, the most diverse, as well as the

  manufacture of different dispersions of chemical fertilizers.

  In the case of suspension stabilization,

  from an economic point of view the manufacture of chemical fertilizers

  in suspension is currently one of the areas

  the most important, and therefore of those whose development

  This is the reason why the principles, the practice and the detailed questions of stabilization will be discussed taking as an example

  chemical fertilizers in suspension.

  Storage, transport of different chemical fertilizers in powder form are linked to significant losses Heterogeneity when spreading is always a disadvantage; the spreading of chemical fertilizers containing different active constituents is only possible in several operations. These problems can be avoided by using suspensions made from chemical fertilizers containing several active constituents, in the event that no one occurs. troublesome sedimentation for the operations carried out, starting from the manufacturing, and passing by the storage, the transport

until spreading.

  The nomenclature of chemical fertilizers in suspension is changing There is no doubt that the components -3 - solids of chemical fertilizers used for manufacturing

  enter the field of coarse dispersions.

  The size and quality of the particles found in the saturated solution of the components, present a complex picture because of the various interactions, processes

  double salt formation, particle precipitation

  The, etc., that occur in the solution The quality of the particles found in these systems or their size according to their material quality, have not yet been subjected to detailed studies on the plan.

  scientist; that's why these systems -

  regardless of particle size analysis -

  are referred to as dispersions as a whole.

  This definition allows for the separate or common presence of both particles that are in the order of magnitude of the colloids and particles that are found

  in the order of magnitude of coarse dispersions.

  In the suspensions, electrolytes are traditionally used to stabilize in order to avoid -sedimentation. These electrolytes cause electrostatic repulsion-forcesbetween

  particles and thereby prevent their agglutination.

  This method is of course not usable in the case of the medium of chemical fertilizer dispersions constituted

  by a concentrated electrolyte solution.

  It is also possible to use for the stabilization of the dispersions, which are designated by the name of colloidal macromolecules, which increase the viscosity of the medium,

  make it more difficult for sedimentation of

  The gelatin, carboxymethylcellulose, polyvinyl alcohol, casein, lignin sulfonic acid, etc., can be used for this purpose. as their derivatives, sorbitol, glucose, etc. It has been proposed to use for the stabilization of chemical fertilizers in suspension, synthetic silicates, various silicic acid derivatives,

  colloidal silicate sols, magnesium silicates -

  aluminum; natural silicates such as bentonite, which is a clay ore, are also used.

  illite, attapulgite, etc. It may also be possible to

  use dispersion agents based on

  phosphated, in association with clay ores.

  In addition to dispersal agents and stabilizers, there is also a need to focus

  on the importance of the action of mechanical grinding.

  The corresponding state of the art is described, for example, in BUZAGH's "raktikum der Kolloidik" (Tank 8 nyvkiadb Budapest, 1962, pages 119-125, 143-149 and 176-199) and in the German patent N 1,667,798 and the Patent

American No. 3,579,321.

  Relatively good stability can be obtained with the methods described, however, in practice,

  in most cases it is necessary again to

  neise the already sedimented components, by stirring,

  in systems -stabilized in this way.

  Another problem is the relatively high price of industrial products, which is determined by energy and material requirements.

  natural by-products and different sub-products

  -products, significant fluctuations in quality constitute an obstacle to stabilization If appropriate, the value of a method considered

  can be reduced when the stability agent

  is a chemical composition which is

  foreign to the materials that make up the land.

  The present invention therefore aims to provide a method that allows the stabilization of suspensions using means available in sufficient quantity, consistent quality and relatively good

  market, usable without chemical transformations

  liereq and not deviating in principle from the natural components of the land. The invention is based on the observation that this goal can be achieved by using starch and

  Urea The Applicant has in fact found

  that starch and urea, which sediment rapidly in water, not only do not sediment when they are together, but also prevent sedimentation of

  solid particles of the dispersion.

  This observation is even more surprising since according to the literature (cf Handbuch der Papierindustrie, Editor-in-Chief: Gy 8 rgy VAMOS, Mtszaki K 8 nyvkiad 6,

  Budapest, 1980, pages 120-122 and 143) the starch can normally be

  to be converted into a system which does not sediment, by degradation by oxidation or by enzymatic, basic or acidic degradation, and the product obtained in this way is, on the other hand, not normally known as a stabilizing agent, but is known precisely as a coagulating agent, clarifying agent or sedimentation agent. Accordingly, according to the invention, water or aqueous medium or dispersion already containing solid particles prior to the preparation of the dispersion is dispersed with starch and carbamide, either separately or in the form of 'a mixture beforehand

prepared dry.

  The amount of starch used for the stabilization is between 1 and 50% by weight, and preferably between 2 and 10% by weight, relative to the water. The amount of carbamide is at least equal to the amount of starch,

  but is not more than 50 times that quantity and is preferably

  between 2 and 10 times this quantity.

  The starch can be used preferably in a non-disaggregated form, and especially in the form

  natural substances containing starch.

  Starch and urea can be used preferably

  in the form of a dry mixture. The process according to the present invention gives, from mixtures of various material qualities, which are soluble in water differently and consist of inorganic and / or organic compounds, a system which does not sediment, which is fluid The process thus fulfills several necessary conditions at a higher level than the state of the art; in particular: It is possible to stabilize suspensions with substances which are not foreign to the components

  soil and living organisms.

  The process is not limited to narrow groups of different materials, the necessary stability being provided on the contrary when using dispersed particles having the most diverse chemical compositions. In chemical fertilizer suspensions, one of the components of the stabilizing agent, namely urea,

  must be considered as a natural component.

  This method makes it possible to extend the field of use of the invention; starch which is an important product of the industry

  which is based on agricultural production.

  The process does not require the isolation of the starch from its natural state, it also works when using grinding products of different plant substances containing starch, such as different kinds of cereals, etc. Besides the preceding provisions, the invention also includes other provisions, which will emerge

of the following description.

  The invention will be better understood by means of the

  additional description which will follow, which refers

  examples of implementation of the process object of the

  present invention, which have no limiting character.

E X E M P L E S

  Comparison Example I 40 g of starch are dispersed in 500 ml of water with continuous stirring. A sedimentation cylinder of 250 ml capacity, a dispersion in the zone of between 100 and 250 ml, is filled with a difference of 2.5 ml The volume of the sedimented substance is read after 1 hour, 2

  hours and 24 hours, then it is determined after a sedition

  24 hours, the character of the sedimentation at

the naked eye.

  After one hour the sediment of the starch falls into the sedimentation cylinder in the non-graduated zone which is below the graduation 100 ml. The sediment forms in 24 hours an extremely compact and very

hard to pour.

Comparison Example 2

  The procedure is as described in Comparative Example

  its 1, with the difference that we disperse extra -

  During agitation, the urea decomposes, so that it is not possible to proceed.

to a sedimentation test.

Comparison Example 3 -

  The procedure is as described in Comparative Example

  its 1, with the difference that instead of starch we disperse 150 g

  of antraquinone After one hour, the sediment of antraqui-

  none falls in the sedimentation cylinder in the area

  not graduated below 100 ml graduation.

  The sediment forms after 24 hours an extremely

compact and hard to pour.

8 -

Example 1-

  The procedure is as described in Comparative Examples 1 to 3, with the difference that 200 g of carbamide, 40 g of starch and 150 g of antraquinone are dispersed in 500 ml of water, with stirring. . No sedimentation, either after one hour or after two hours, was observed in the sedimentation cylinder; after 24 hours, 5 ml of clear medium were observed above the sediment. After 24 hours of sedimentation no sediment was formed, the dispersion remained homogeneous

and easy to pour.

  Comparison Example 4 The procedure is as described in Example 2, except that in place of the 200 g of carbamide, 200 g of potassium chloride are dispersed.

  only potassium chloride has dissolved.

  After filling the sedimentation cylinder with the suspension formed in the saturated KCl solution,

  forms a system that sediments extremely rapidly.

  The sediment falls after only one hour, in the non-graduated zone which is below the graduation ml. The sediment forms in the space of 24 hours a

  extremely compact layer, difficult to pour.

  Comparative Example The procedure is as described in Comparative Example 2, with the difference that it is monoammonium phosphate which is dispersed during the production process.

  dispersion, some of the monoammonium phosphate dissolves.

  The monoammonium phosphate saturated suspension sediments rapidly in the sedimentation cylinder: indeed, after only one hour, the sediment falls in the zone

  not graduated below 100 ml graduation.

  After 24 hours, the sediment is loose, but its volume is extremely low; it is very easy to pour, without problem, Comparison Example 6 The procedure is as described in Comparative Example 5, except that 150 ml of sodium hydroxide are added during the suspension operation. 25% ammonium suspension The suspension sedimented in the sedimentation funnel with a capacity of 250 ml, slower than observed in Comparative Example 5, but despite this, the volume of the sediment falls from the end

  one hour a little below graduation 100 mi.

  The sediment can be poured relatively easily at the end

24 hours.

Example 2

  The procedure is as described in Comparative Examples 1 and 2 except that 500 g of water, 500 g of urea and 250 g of starch which have been previously dry-blended are dispersed in the system. extremely high ', and it is made more difficult to pour by its viscosity The system does not sediment even at the end

24 hours.

Exem Section 3

  The procedure is as described in Example 1, with the difference

  In addition, 1870 g of urea, 40 g of starch, 1000 g of monoammonium phosphate, 900 g of 25% ammonium hydroxide and 880 g of potassium chloride are dispersed.

  650 ml of water, in accordance with the nitrogen-phosphorus-po-

  tassitum 1: 0.5: 0.5 The dispersion thus formed, which has a content of active constituents of 40%, does not sediment in the sedimentation cylinder after one hour and two hours, respectively; after 24 hours 7.5 ml of clear medium is formed above

  the surface of the suspension No sediments are formed

  The suspension can easily be poured.

Example 4

  The procedure is as described in Example 3, except that -

  720 g of urea, 1000 g of monoammonium phosphate are dispersed

  and 40 g of starch in 30 ml of water and 900 g

  of ammonium hydroxide in a nitrogen-phosphorus

  potassium 1: 1: C 'The dispersion thus formed, which has a content of active constituents of 40%, does not sediment in the sedimentation cylinder of 250 ml capacity, nor in the space of one nor in the space of After 24 hours, 5 ml of clear medium is formed above the surface of the suspension. It is not necessary to homogenize.

  The suspension is easy to pour.

Example 5

  The procedure is as described in Example 3, except that it is dispersed in 710 ml of water,

  900 g of armonium hydroxide, 1000 g of monoammonium phosphate

  720 g of urea, 880 g of potassium chloride and g of starch, in a ratio nitrogen-phosphorus-potassimm of 1: 1: 1 The dispersion thus formed, which has a content of active constituents of 40%, does not sediment in the sedimentation cylinder of 250 ml capacity, either after one hour or after two hours After 24 hours, 10 ml of clear medium is formed above

  the surface of the suspension No sediment is formed.

  The suspension can be easily paid.

Example 6

  The procedure is as described in Example 3, with the difference that 720 g are dispersed in 920 ml of water.

  of urea, 1000 g of monoammonium phosphate, 900 g of hydro-

  ammonia hydroxide, 1860 g of potassium chloride and 50 g of starch, in a nitrogen-phosphorus-potassium ratio of 1: 1: 2 The dispersion does not sediment, either after one hour or at the end of two hours After 24 hours, 2.5 ml of clear medium is formed above the surface

of the suspension.

  11 - It does not form sediment Suspension is easy

To pour.

Example 7

  The procedure is as described in Example 3,

  except that 300 g of ammonium hydroxide, 280 g of urea, 1000 g of monoammonium phosphate, g of ground cereals containing starch and 1350 g of potassium chloride are dispersed in 1100 ml of ammonium hydroxide. water, in a nitrogen-phosphorus-potassium ratio of 1: 2 ': 3 _ Dispersion 1 O does not sediment in the sedimentation cylinder, nor after one hour-nor after two hours After 24 hours 12.5 ml of clear medium is formed above

  of the surface of the suspension It is not formed of.

  Sediment The suspension can be easily poured.

j 5 Example 8

  12-5 g of urea, 1250 g of monoammonium phosphate, 375 g of ammonium hydroxide, 20 g of starch are dispersed.

  and 2656 g of potassium chloride in 1750 ml of water.

  The dispersion thus formed, containing 40% of active constituents, does not sediment in the sedimentation cylinder of 250 ml of capacity, neither after one hour nor after two hours After 24 hours, 15 ml is formed of

  limpid medium above the surface of the suspension.

  It does not form sediment The suspension can be

easily paid.

  As is apparent from the foregoing, the invention

  tion is not limited to those of its modes of implementation, of realization and of application which come, to be described in a more explicit way; on the contrary, it embraces all the variants that may come to the mind of the technician in the field, without departing from the

  nor the scope of the present invention.

12 -

Claims (3)

  1 / A method for preparing aqueous dispersions, not sedimenting, by dispersion of solid particles in water, characterized in that prior to the preparation of the dispersion, it is distributed in water or in the aqueous medium or in the dispersion already containing   solid particles, 1 to 50% by weight, and   2 to 10% by weight of starch, as well as urea in an amount which corresponds at least to the mass of starch, and is at most 50 times this mass, and is preferably between 2 to 10 times amount of starch.   2 / A method according to claim 1 characterized in that   starch is used in a non-disaggregated form,   in the form of natural substances containing starch.   3 / A process according to Claim 1 or Claim 2, characterized in that starch as well as carbamide   are used in the form of a dry mixture.