CA1269860A - Process and composition for the anticlumping of non- powdery salts or fertilizers - Google Patents

Abstract

ABSTRACT

The invention relates to a process for the anti-clumping of non-powdery salts or fertilizers, characterized by the fact that there is sprayed onto the constituent particles of the fertilizer, after drying and before storage, at a moment when said particles are in their final form and have acquired almost the whole of their final mechanical properties, an effective amount:
- either of an aqueous solution of alkali or amine silicate whose content of dry matter is from 15 to 60% by weight, this application being preceded or followed by an application of an anionic surfactant in aqueous or oily solution, - or of an aqueous solution of alkali or amine silicate comprising an anionic surfactant in the form of an alkali or amine salt, - or of one of the preceding products, associated with an oil or with a fuel and/or if necessary with an inert mineral coating agent.

Description

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.. 1 _______________________________________________ NON-POWDERY SALTS OR FERTILIZERS
________________________________ ~ he invention relates to a process and composi-tion for the anti-clumping of non-powdery salts or fer-tilizers.
For the term "fertilizers" is meant both simple fertilizers and complex fertilizers and by ths expres-sion "non-powdery" salts or fertilizers, any type of presentation of these products in which the latter are in the for~ of granules, grains, beads, small cylinders or prills obtained by means of processes denoted in the technique by "prilling", granulation in a drum, on a plate, by a screw, or by fluidized bed.
The above-said salts being treatable within the scope of the invention comprise particularly calcium phosphate, chloride and potassium nitrate.
The above-said "simple" fertilizers comprise urea, ammonium sulfate, and particularly ammoni~m nit-rate; in the latter case it may be pure ammonium nitratethat is to say whose titer (~0 of nitric and ammoniacal nitrogen by weight ~ith respect to the weight of ferti-lizer) is 34.8% or of dilute ammonium nitrate and of which the titer is reduced to 33.5%, 30%, 27.5%, 20%
and 20% and so on.
The so-called "complex" fertilizers are fertilizers ranging to the nitrogen of other nutrient elements of vegetation; they comprise fertilizers of the N.P.K. type (fertilizers contrlbuting to the plant ni-trogen, phosphorus and potassium) and any combination inpairs of these elements, as the case may be associated with the necessary oligo-elsment~.
Fertilizers of the N.P.K. type are defined by their nitrogen titer expressed in % by weight of ritro-gen with respect to the fertili~er and/or by their pho6-phorus titer expressed in % by weight of pho~phoric an-` ~2~;~3~6~

hydride with respect to the fertilizer and/or by -their potassium tlt0r expressed in % by weight of potassium oxide with respect to the fertilizer.
It is well known that the above-said salts and fertilizers, when they are stored either in bulk or in the form of piles can reach 15 to 20 m in height, or in bags piled over several stories which can reach 12 m have a tendency to clump, that is to say to set so-lid.
This iæ a poorly known complex phenomenon, which causes a considerable cohesion between the grains or prills, preventing them from rolling freely and causing clumping, that is to say setting solid of the pile which is all the greater as it is nearer the bottom of the pile or the stack of bags; this setting solid may sometimes reach proportions such that the fer-tilizer takes the form of a compact hard mass or largeblocks which are extremely difficult to break up: the fertilizer is then no longer uæable as such but must be broken up and recycled, which involveæ a considerable further exploitation co~t for fertilizer manufacturers.
One of the possible cause6 of clumping~ par-ticularly ~or very hygroscoplc and deliquescent ferti-lizerR, like ammonium nitrate, re6ides in the varlations of humidity and temperature at the surface of the grains, phenomena which cause a sur~ace dissolution of the fertilizer and its recrystallization with crystal-line bridges between neighbouring grains on drying.
When small amounts of ammonium nitrate (of the order of 100 grams) are æub~ected to pressure and to cycles of humidity and temperature, such phenomena are indeed ob~
served. However, this deliqueæcence of the fertilizer grains is not the real cause of clumping 6ince it is currently admitted that at the heart of a pile, where the clumping is a maxlmum, there is no exchange of humi-dity with the outer surrounding air and the pile is adi-abatic; the explanation which has just been provided is therefore only valid for a very superficial layer of a pile.
To combat this clumping or setting æolid, it has already been proposed to resort to inorganic coat-ing agents possibly associated with organic products such as surface active agents, oils, polymers and the like; various organic treatments have also been propo-sed, without mineral coating, by means of amine soluti-ons in oil, of surface active agents associatedwith waxes and the like.
It has al60 been proposed (US patent 1,932,434) to combat clumping of ammonium nitrate powders, to modi-fy the crystallization of the ammonium nitrate by incor-porating a solution of concentrated sodium silicate in the solution of ammonium nitrate before it~ final concentration, the nitrate being obtained in the form of powder; such powdered nitrates are practically no longer marketed and no longer respond to present needs.
The use as also been proposed as anti-clumping agents of silicates insoluble in water or of insoluble alumino-sillcates (US patents 2,407,151, 2,903,349 an~
3,190,774), the silicates or alumino-silicates being possibly associated with surface active agents; a modification of this technique (US patent

2,660,541) consists of precipitating the insoluble alu-mino-silicate at the surface of the fertilizer whose temperature i6 higher than 105C by spraying thereon an alumina dispersion finely ground and dispersed in an al-kali silicate. At this temperature, the alumina reacts on the alkali silicate and forms an insoluble alumino-silicate.

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The employment on fertilizers of insoluble sili-cates and silico-aluminates, generally in a coating ag-ent, does not permit a very homogeneous distribution thereof and even in the presence of a surfacc active ag-ent or of oil there is not obtained a totally satisfac-tory anti-clumping action in all cases; besides, the use of larger amounts of surface agents to arrive at an acceptable result can be troublesome with regard to the mechanical properties of the fertilizer grains.
Moreover these treatments are often extremely dusty.
It is a particular object of the invention to overcome the drawbacks of the prior art and to provide an improved anti-clumping process and composition for non-powdered salts and fertilizers of the type concern-ed.
And it is to the merit of Applicant Company tohave been able to perfect, as a result of extensive re-search, a process adapted to permik unexpectedly very effective anti-clumping of non-powdered salts and fertilizers of thfl type concerned, this process being characteriæed by the fact that th0re is applied to the constituent particles of fertllizer, aPter at least par-tial drying and before storage, at a moment when said particles are in their final form and have acquired al-most the totality of their final mechanical properties, an effective amount:
- either of an aqueous alkali or amine silicate solution whose content of dry matter is 15 to 60% by weight, this application being preceded or followed by an application of an anionic surface active agent in the form of an alkali, alkaline-earth or amine salt, - or of an aqueous solution of alkali or amine silicate comprising an anionic surface active agent in the form of an alkali, alkaline-earth or amine salt as-sociated with a surface active agent in tha form of an ~ 3~

alkali, alkaline-earth or amine salt in oil or water so-lution, - or of one of the preceding products, associat-ed with an oil, a wax, a vaseline, a paraffin or with a fuel and/or possibly with an inert mineral coating agent.
The anti-clumping composition according to the invention is, for its part, characterized by the fact that it is based on an aqueous solution of an alka-li silicate or of an amine and at least one anionic sur-face active agent in the form of an alkali, alkaline-earth or amine in aqueous or oil solution, the respec-tive parts by weight of silicate and of surface active agent being 10/90 to 90/10.
The above-said solution can also include an effective amount of paraffin fuel of wax or vaseline or of oil, the whole then being in the form of an emulsion. Such an emulsion can include, according to the invention, - from 1.6 to 2-1.6% on dry matter of alkali or amine silicate, - from 21.6 to 1.6 on dry matter Or surface ac-tive agent, - from 40 to 60% of fuel, wax or oil, the complement to 100 being constituted-by water, Apart from the above-said features, the inven-tion is aimed also at other features which are used pre-~erably at the same time and will be considered.
It will be well understood by msans of the complement of description which follows and of the ex-amples, said additional description and examples illus-trating advantageous embodiments.
Proposing, consequently, to effect anti-clumping _ of non-powdered salts and fer-tilizers of the type con-cerned, procedure is as follows or in equivalent ma~ner.

i't38~i(3 There is applied to the grains or prills or spherules of salt or fertilizer in their final form, that is to say after prilling or granulation and drying, when the grain has acquired almost the integrality of its final mechanical properties and-- before storage, at least one solution of alkali silicate and of amine whose content of dry matter varies between 10 and 60% by weight.
And an anionic surface active agent in the form of a salt in aqueous solution or in solution in an oil, a wax, a paraffin, a v~seline or a fuel. The anionic surface active agent in the form of a salt may be mixed with the silicate, then forming a comp~sition according to the invention, or be employed before or after the silicate.
Finally, it is possible to associate with the above-said treatments a treatment with an oil, a fuel andtor an inert mineral coating.
More particularly, in the case o~ granulated or prilled ammonium nitrates whose titer varies between 33.5% and 34.8%, the process according to the invention is advantageously applied to the cooled fertilizer at the outlet of the cooling drum at the end of the fluidized bed or of any other cooling system. The tem-perature of the fertilizer is then generally less than40C and often less than 32C which is th~emperature of the first transition point of the fertilizer. The hu-midity of the grain is then generally less than 1%, cur-rently comprised between 0.1 and 0.~% and the nitrate grain has acquired almost the totality of its final mechanical properties.
In certain particular installations, the process according to the invention can be employed on the partially cooled fertilizer, for example at a tempera-~6~

ture comprised between 80C and 40C. The treated fer-tilizer is then again cooled to -the silo storage temperature.
In the case of ammonium nitrates whose nitrogen titer is less than 33.5% and which, in most cases, con-tain chalk, the process according to the invention is employed after dilution to the desired titer and after granulation or prilling, drying and cooling. The residual moisture is generally less than 2% and in prac-tice comprised between 0.1 and 1%.
After cooling the temperature of the grain isgenerally less than 50C. The grain has then acquired almost the whole of its mechanical properkies and the treatment according to the process according to the in-vention is adapted to the specific characteristics ofthe fertilizer for the desired per~ormance.
In the case of complex fertilizers of the N.P.K. type, the process according to the invention is employed at the end of the production process when the fertilizer has been dried and cooled and its humidity is comprised between 0.1 and 3% and, more ~enerally, be-tween 0.2 and 1%.
Fertilizers have very different behaviours with respect to clumping.
Certain fertilizers have a kendency to clump fast and very strongly, others clump much more slowly.
These differences are connected with a given type of fertili~er, but it was observed that, for the same type of fertilizer, for example, ammonium nitrake whose 30 nitrogen titer varies between 33.5% and 3~.8%, the clumping can depend on the additives used for the granu-lation or for the hardening, on the diluent placed in the mass to lower the titer from 34.8% to 33.5%, but also on the manufacturing process, on the method and - 35 speed of cooling, and so on. For example, in complex fertilizers like the N.P.K.s, certain formulae are very 6~3 clumping and others not. And for a given formula, the clumping may be associated, here again, with the manufacturing process, with the impurities contained in raw materials.
The process according to the invention may ad-vantageously be adapted to the type~of fertilizer to be treated and to the difficulty of the anti-clumping, as shown in the examples.
The silicateæ employed according to the inven-tion are aqueous solutions of alkali or amine silicates whose content of dry matter varies between 15 and 60%.
The alkali silicates are the silicates of lithi-um, sodium and potassium, the preferred silicate being sodium silicate.
They are characterized by the molar ratio SiO2 / Na20 = n, that is to say by the number of molecules of silica associated with a molecule of alkali metal oxide. The alkali silicate solutions currently available in com-merce have ratios which vary between 1 and 4. If theratio is close to 1, the pH of the solution is substan-tially higher than when the ratio is clo~e to 4. Through this fact, when the ratio is close to 1, the silicates are more difflcult to handle, which can in certain cases exclude their use.
The amine silicates may be represented by SiO2 / (NR4)20.H20 where R represents alkyl or hydroxyalkyl radicals pos-sibly substituted.
Specifying that it is not intended to be limited by the explanations which follow, Applicant Company be-lieves that, within the scope of the process accordin~
to the invention, the action of silicates is associated with the more or less rapid insolubilization of the sil-ica at the surface of the fertilizer grains. Under these conditions, the silica precipitates either in the 6~:~

form of a silica hydrogel, or in the form of very divi-ded silica. This precipitation at the surface itself of the grain ensures excellent adherence of the treatment to the fertilizer and good homogeneity of the treatment over the whole of each grain contrary to inert silicates or coating agents, insoluble in water, of the prior art which are preferentially fixed to certain portions of the grain and which, moreover, have very poor adherence and become powdery in time.
The precipitated silic~ ensures excellent prote-ction of the grain and good isolation of the grains from one another and facilitates the flow of the grains. In addition it is hydrophobic and protects the grains against moisture.
The rapidity of the precipitation of the silica at the surface of the fertilizer depends on the type of fertilizer to be treated.
In the case of ammonium nitrates whose titer varies between 33.5% and 34.8%, the surface pH of the grains is generally less than 7 and varies generally between 4.5 and 6.5. It is sometimes less if -the nit-rate is not ~aturated with ammonia before granulation or prilling. When this fertilizer is treated with a sili cate according to the invention, an immediate release of ammonia is observed, which corresponds to the attack of the ammonium nitrate by the sodium silicate which is a basic salt and which causes the immediate precipitation of the silica. The so-treated fertilizer grain has a mat appearance.
In the case of other fertilizers, the pH of ~he grains is generally a little higher and can reach 7 to 7.5. In this case, the precipitation of the silica is less rapid.
For certain applications, too high a pH associ-ated with a ratio n close to 1 may be a drawback; this is the casè, for example, for ammonium nitrate, the us~

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of such solutions causing too great a release of ammonia. In addition, in such solutions, the amount of SiO2 contributed per liter of anti-clumping product ap-plied is lower and this drawback cannot be compensated by the use of more concentrated solutions, their solu-bility being insufficient. In fact, the amount of SiO2 applied by the anti-clumping treatment is considerable.
The silicate~ whose application according to the invention is preferred are those whose ratio varies be-tween 2 and 4; the choice of silicate will be made ac-cording as treatment is separate or in a mixture with a surface active agent or in the form of an emulsion with a surface active agent and an oil or a fuel and accord-ing to the type of fertilizer to be treated.
Thus, for example, in the case of the treatment of ammonium nitrate with sodium silicate followed by a surfactant or an oil (in this order or in the reverse order), the silicates of ratio n = 2 or n = 4 are shown to be practically equally effective.
On the other hand, in the case of a treatment with an association of surfactant silicate used conjoin-tly, it is a silicate of ratio 2 which seems to be the best compromise both for problems of compatibility of the formula and for problems of direct effectiveness.
In the case of the treatment of fertilizers of the N.P.K. type, whether this i8 by a silicate alone or associated with a surfactant, all the silicates whose ratio is comprised between 2 and 4 are suitable accord--ing to the various cases to be reckoned with.
Potassium silicate in certain applications is shown to be slightly poorer particularly on N.P.K. than sodium silicate.
The silicates whose use according to the invention is preferred, are the alkali silicates _ 35 in aqueous solution whose content of dry matter varies between 15 and 60~ and more particularly, sodium sili~

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cate in concentrated solution, this in order to contri-bute the least water possible to the fertilizer.
It is especially the case ln the treatment of ammonium nitrate which is currently dried for anti-clumping treatment until the residual moisture is com-prised between 0.1 and 0.4% in order to improve the mechanical properties of the grain.
The process according to the inven-tion is then placed in operation, generally, doses such that there is not contributed more than 0.03% to 0.1% of maximum mois-ture to the grain in order not to spoil the mechanical properties of the grain.
In the case of fertili~ers of the N.P.K. type, the final moisture is of the order of 0.2 to 1% and sometimes more. Here again, the treatment is calculat-ted in order to not increase too much the moisture of the g~ain, which would have the effect of spoiling its mechanical properties, but the influence of the water is less prejudicial than in the case of nitrates.
The choice of silicate according ko the inven-tion is done therefore according to the pH of the latter either for problems of handling and of compatibility with the fertilizer, or, as the case may require, for formulation problems with a surfactant. It is also se-lected so as to precipitate rapidly in contact with the fertilizer and so as to contribute the amount of pre-cipitable silica necessary for the treatment whilst only contributing the minimum of water compatible with the fertilizer.
The alkali silicates used within the scope of the process can be according to the invention concentra-ted solutions of commerce whose dry extract varies be-tween 35 and 60% as a function of the ratio n; they may be possibly diluted with water but so that the content of dry matter is not lesc than 15% and the spacific gra-BIii(3 vity of the solution is not less than 1.1.
Applicant Company does not wish to be limited by the explanations which follow but it is of the opinion that one of the roles of the surfactant is to facilitate the contact between the silicate and the fertilizer grains. In fact, the silicate has not intrinsically a good filmogenic power. Thus, for example, when it i5 sprayed onto a flat surface, the silicate is deposited in the ~or~ of small droplets which do not spread and do not necessarily wet the whole of the surface. In this case, a surfactant in aqueous solution is sprayed before the silicate solution, or incorporated with it, or sprayed after, and permits this drawback to be reme-died.
In the same spirit, Applicant Company believes that another role of surfactants is to contribute in as-sociation with the anti-clumping effect of the silicate a complementary anti-clumping effect due to the hydro-phobic effect and to a role of modification of crystal-lization.
The surfactant whose application is proposed within the scope of the process according to the invention are an-ionic surfactants. Among the anionic surfactants, may be mentioned:
- C12 to C20 fatty acid~, among which are particularly stearic acid, - soaps, - alkyl-aryl-sulfonates~
- alkane-sulfonates, - sulfates of fatty alcohols or of phenol possibly oxy-ethylenated, - phosphates of fatty alcohols or of phenols possibly oxyethylenated, - alkanolamide sulfates, - alkylalkanolamide sulfonates, 6~B6~

alkyl-polypeptides, alkyl-sarcosinates, - sulfated derivatives of glycerides, - alkyl-sulfo-acetates, - alkyl-sulfosuccinates, 5 - alkylamido-sulfosuccinates.
These anionic surfactants may be used in water (water-soluble) or in organic solvents (fat-soluble).
The choice of surfactants applied within the scope of the process according to the invention depends on numerous factors such as the nature of the fertilizer to be treated, its porosity, its natural tendency to set solid, its hardness, the type of industrial installation used, the appearance of the grain obtained, storage and the destination of the fertilizer and the like.
Th~s, ammonium nitrate is a stable product if it is very pure but can be dangerous if it is acid and if it contains too large amounts of organic substances.
There then occur decomposition reactions which may lea~
to an explosion; consequently only particularly stable surfactants will be employed like, for example, arylal-kyl-sulfonates and alkane-sulfonates.
One of the advantages of the compositions based on concentrated alkali silicate and a surfactant is that the arnount of organic substance necessary for the anti-setting of the fertilizer can be reduced.
One of the other advantages of the invention as-sociated with its high effectiveness is that for certain fertilizers difficult to render anti-setting like cer-tain ammonium nitrates it was customary to use an oil containing 15 to 30% of a fatty amine like stearylamine and an inert inorganic coating like kieselghur.
Fertilizers thus treated are powdery, the powder being both due to a re-emission of the inorganic coating _ substance and to the formation of fertilizer dustO The treatments according to the invention like, for exa~ple, -~LZ~j9B6~

with an alkali silicate solution and sodium alkylnaphth~
lene sulfonate are distinctly ~ore effective and do not cause any dust-formation of the fertilizer.
In other types of fertilizers where this problem S of a danger does not exist, it is experience and in par-ticular the desired effectiveness which govern the choice of surfactant applied.
In certain installations, it is possible to em-ply a single product~ The composition according to the invention can then comprise an alkali silicate and a surfactant, the latter being selected as a function of its compatibility with the silicate. In fact, the sili-cates are only stable in a slightly basic medium. Also, the surfactant employed in this case must be stable at these pHs and be selected very particularly so that the final mixture does not dephase or saIt out over time and can be applied whilst preserving its anti-clumping activity.
In certain cases, the anti-clumping composition comprises an oil, a wax or a fuel; the surfactant is then selected so as to give a stable emulsion "alkali silicate -- oil or fuel -- surfactant", not losing its properties at the tim~ of use, The oils or waxes which may be comprised by the compositions according to the inventlon are waxes or mineral oils like paraffin, naphthene or aromatic oils, or particularly stable natural oils, petrolatums or vaselines, paraffins; the oils are selected for their lubricating power and their hydrophobic power; they must ~o be non-migrating and if possible solidify as soon as they are in contact with the grain.
As indicated above, ~he composition according to the invention can include an inert coating a~ent, par-ticularly when it is a matter of treating certain fer~
tilizers particularly difficult to render antl-clumping -like for example certain N.P.K.s.

Among these coating agents, may be mentioned talc, chalk, kaolin, kieselauhr, diatomaceous earths, clays, infusorial earths, natural silico-aluminates ground or precipitated, and the like.
When the composition employed within the scope of the process according to the invention is liquid, it is advantageously sprayed in the form of a fog of very fine droplets in order to reach and coat the totality of the grains of fertilizer or of salt.
When it is a matter of aqueous solutions of sil-icates or surfactants, or a mixture of both, or again emulsions obtained by the introduction of fuel of an oil into the surfactant-silicate rnixture, the spraying is at ambient temperature or after slight heating.
The spraying can be carried out by means of well-known systems such as sprayers with nozzles of the airless type or with secondary air nozzles, In the first case, the composition is pumped and sent under a pressure of 2 to 30 bars to nozzles where it brea~s up into micro droplets.
In the second case, the composition is sent un-der very low pressure just into the nozzle and it is an air jet under pressure which causes the br0akup into droplets.
Wh~n the composition accordin~ to the invention includes a surfactant in solution in a wax, a paraffin, a vaseline, an oil or a fuel, this composition is ad~an-tageously preheated to temperatures which can reach ~0C
to reduce its viscosity and sent under pressures which can reach 100 bars into airless nozzles where it is sprayed.
In all cases, the diameters of the nozzles and the supply pressures of liquid and/or of secondary air are calculated so as to ensure the right dosage onto the - 3S fertilizers of one or more products applied.

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The number of spray nozzels depends on the ins-tallation and on the hourly flow rate of fertilizer.
In general, 1 to 3nozzles suffice to applythe liquid compositions employed within the scope of the process according to the invention.
Accordin~ to the process according to the inven-tion, the anti-clumping compositions are applied to the fertilizer at the final stage of its manufacture The doses of anti-clumping composition employed within the scope of the process accordlng to the inven-tion can vary from 0.2 to 40 per thousand by weight with respect to the weight of fertilizer.
These doses vary as a function of the constitu-ents of the anti-clumping composition and the type of fertilizer to be treated. They -take into account the nature of the fertilizer, its composition and its method of manufacture, its particular aptitude to clump and its physical properties.
It takes account also of the constituents o~ the composition applied to the fertilizer.
When, within the scope of the process according to the invention, an alkali silicate and a surfactant are employed, the respective do~es of silica and of sur~actant can each vary from 0.02 to 7.2 per thousand but so that the global dose which is the sum of the two particular doses is from 0.2 to 8 per thousand by weight with respect to the fertilizer; more prefPrably still, the dose concerned varies from 0.5 to 3 per thousand by weight with respect to the fertilizer.
When, within the scope of th~ process according to the invention, there is employed a composition based on a surfactant and an alkali silicate or amine, the dose supplied to the fertilizer varies from 0.2 to 8 per tho~sand by weight with respect to the fertilizer~
the ratio of dry matter al~ali silicate to surfactant in the composition according to the invention varying from ~ 39~36~

1/3 to 9, which signifies that the respective propor-tions of alkali silicate and of surfactant vary from 10/90 to 90/10 ~expressed as dry/dry). Still in this case, the preferred doses vary from 0.5 to 3 per thousand by weight with respect to the fertilizer, more preferably ~rom 0.6 to 1.6 per thous-and by weight.
When within the scope of the process according to the invention, there is also applied a fuel, an oil, a vaseline, a paraffin or a wax, ths dose of the latter product can vary between 0.2 and 5 per thousand by weight with respect to the fertilizer, the preferred doses being comprised between 0.6 and 2 per thousand.
Finally, when, within the scope of the process according to the invention, there is also applied an inert mineral coating agent, there is added to the previously described doses doses o~ a coating agent which can vary between 1 and 35 per thousand by weight with respect to the fertilizer, the preferred doses of a coating agent varying in practice from 2 to 8 per 20 thousand.
To establish the effectiveness of the anti--clumping process and of the anti-clumping composition according to the inventlon, Applicant Company has car ried out various tèsts and measurements.
Among these measurements or tests, will be men-tioned firstly the test called "clumping box" test.
This test enables in a very short time a comparison be-t~reen them and with respect to a control, the behaviour of fertilizers treated by various products; it permits 30 a rapid response to be obtained, but on the contrary it is not really representative of the behaviour of a fer-tilizer on storage.
Within the scope of this test, the fertilizer is placed under pressure in a climatic enclosure of ~Ihich 35 the ambient temperature and humidity are made to vary cyclically. In practice, the fertilizer is placed in a .....

perforated cylinder and sub~ected to constant pressure by means of a piston sliding freely in the cylinder con-taining the fertilizer; the piston is loaded, with a given weight so that the pressure exerted is of the order of 0.8 kg/cm . Several cylinders of this type are placed in a climatic enclosure where the relative humi-dity is made to vary at the same time as the temperature For example, it is possible to vary the relative humi-dity bet~een 80% and 40%, the temperatures varying sim-ultaneously between 31C and 24C. Such cycles can beeffected for example every twelve hours, After 2 or 3 days, the sample of fertilizer is taken up again and its condition observed. I~ the grains of fertilizer are not absolutely joined to one another, the fertiliæer flows; this property is denoted in the technique by the English term "free flowing" which can be translated by "s'écoulant libre-ment". If the grains are lightly bonded to one an-other, the fertilizer has preserved the form of the cy-linder in which the test was carried out but the cohe-sion between the grains may be sufficiently low for the cylinder -to crush a~ soon as it is handled.
On the other hand, if the grains are strongly bonded to one another, the fertilizer is in the form of a hard cylinder and the degree of clumping is e~ti-mated by the force necessary to crush this cylinder, for example, between the plates of a dynamometer.
It is considered that the anti-clumpin~ process is effective if it gives a "free-flowing" fertilizer or cylinders which are crumbly. In other cases, treatment is all the better as the forces necessary to crush the cylinder are weaker. To have a reliable respon~e, a half score of specimens are formed for each compositlon with several repetitions in several boxes. The results _ 35 are expressed by the ratio between the force necessary to crush the treated fertilizer and that necessary to 36~) lg crush the control.
Rather than resort to the clumping box test, it is preferred to measure the anti-çlumping effectiveness of various compositions by packaging the treated fertilizer in bags and subjecting these bags to consid-erable pressures over fairly long periods and which can reach several months.
It is advantageous, for example, to arrange these bags in four on pallets and to load these pallets so as to produce pressures which can reach 0.3 to 5 kg/cm .
Then, the fertilizer is taken up again anditS
behaviour is observed. If the fertilizer has not clum-ped, the grains are perfectly free from one another and the contents of the bag flow easily without observing small lumps. In the case of partial clumping, lumps are observed in the bags and the tendency to clumping is estimated first by weighing the lumps and by relating their weight to the weight of fertilizer in the bag and also by evaluating the hardness of these lumps, that is to say by measuring the force necessary to break them upIn the case of total clumping, the fer-tilizer contained in the bag is in the form of a block and it then becomes convenient to measure the force ne~
cessary to reduce this block.
It is considered that an anti-clumping process gives results which are all the better as less :lumps are observed for the longest storage under highest pres-sures and, if there are -lumps, the latter are as fri-able as possible.
The anti-clumping process must not make the fer-tilizer grains fragile nor reduce their hardness. For this, it is convenient to compare the hardness of the treated grains and the untreat~d grains by means of a hardness meter which measures the crushing ~trength of the grain between two rods. It i5 also intereæting to 36~

measure the hardness of the grains afker clumping. In fact, after considerable clumping, the cohesion of the grains diminishes which also permits a classification of the anti-clumping treatments with one another.
It is sometimes inevitable that fertilizers are stored under difficult climatic conditions. This is the ca~e, for example, of hot and humid countries or again storages in bulk in unenclosed hangars. It is then ne-cessary for the anti-clumping process to bestow a hydrophobic character to protect the fertilizer from variations in atmospheric humidity. It will then be in-teresting, to compare the anti-clumping treatments, to measure the taking up again of moistu~e of the fertili-zer treated in atmospheres of variable relative humidi-ty.
Often, on taking up again fertilizers at the silo, a new release or formation of dust either of the coating agent used for the outside of the grain, or of "fine fertilizer particles", that is to say of fertilizer grains which are loosened or crumbled on ac-count of the clumping, is observed. It is important to evaluate the influence of the anti-clumping process on --r this dust formation phenomenon. To do this, the ~ertilizer is subjected to one or several drops from a height of 1 m inside a closed cylinder in a flow of air which entrains the poorly fixed coating Rgent or the fine fertilizer particles which are recovered by filtering the air on a diaphragm; these entrained pro-ducts are then welghed.
The result is all the better as the amount of dust released i5 less. This amount is more easily ex-pressed with respect to the untreated fertiliæer. ~t is also important to analyze this dust to distinguish the portion due to the coating agent and the portion due to the fertilizer.

~'9B~
.

The following examples are intended to render the scope of the invention better understood, to dernon-strate its advantages with respect to the prior art but however not to be regarded as limiting.
In these examples which relate to advantageous embodiment~recourse is had to various anionic surfact-ants of which the method of manufacture are described in the following. The class of surfactants advantageously used according to the invention is that of alkali, alka-line-earth or amine alkyl arylsulfo-nates, more particularly that of alkali, alkaline-earth or amine polyalkylnaphthalene sulfonates.
Their manufacture is well known.
It is possible for example to react various am-ounts of alcohol like propanol, isopropanol9 butanol, isobutanol, amyl alcohol, isoamyl alcohol, etc. on naph-thalene or naphthalene cuts based on methyl-naphthalene or dimethylnaphthalene in the presence of 98% sulfuric acid and/or 20% oleum to obtain the desired alkylated and sulfonated derivative. The excess dilute acid ob-tained at the end of the reaction is removed by decanta-tion and the polyalkylnaphthalene sulfonic acid obtained is neutralized by an alkali or alkaline-earth, an amine, the excess sulfate being if necessary removed by filtration or precipitation ln the cold.
A product advantageously used according to the invention is that obtained, for example, from 2 moles of alcohol like isopropanol or isobutanol, naphthelene or a cut rich in methylnaphtalene. This product is advanta-geously sulfonated with an excess of 20% oleu~ so that all the nuclei are alkylated and are at least monosulf-anated. The excess acid necessary is of the order 3 times the stoichiometric amount with respect to the num-ber of aromatic nuclei used. This product may be neut-ralized ~ith an alkali like for example soda or potash, a short amine like monoethanolamine when it is desired to obtain a water soluble product.
This product may be associated with soluble salts of ~ - naphthalene sulfonic acid polymerized with formol.
We will call, in the following solution, A such 5 product in the form of a sodium salt containing 20% ex- b pressed in dry matter on dry matter of polymer of poly-merized sodium~ -naphthalene sulfonate polymerized with formol the whole in a 45% aqueous solution on dry matter.
We will call solution B the same product 10 but neutralized with monoethanolamine in a solution with 40% of dry matter.
It may sometimes be advantageous to use such products in oil solution to relnforce the hydrophobic power of the treatment.
We will call solution C the product as described above obtained with 2 moles of alcohol neutralized with fatty amine like stearylamine in an oil.
Its composition is as ~ollows:
alkylnaphthalene sulphonic acid = 11.5 alkylamine mainly C18 cut = 15.0 stearic acid = 18.5 oil (for example SW50 of ~.P.) = 55 In this type of composition it is advantageously possible to replace stearic acid by paraffinic 25 waxes of polyethylene, etc.
We will call solution D the product contained as described above but with ~ moles of isobutanol or butan ol reacted with naphthalene or methylnaphthalene and neutralized with a fatty acid like stearylamine in an 30 oil solution ~for example SW50 of B.P.).
Example 1:
An anti-clumping composition called composition no. 1 and whose constitution is as followsis prepared:
Solution A previously described 43.8 Water 9 ~
30% Soda solution 4.0 l X6~B~i'O

Dry extract sodium silicate 46.4% and of ratio SiO2/Na20 = 2.1 42.6 100 .0 The composition no. 1 shows a 40% dry extract~
In a concrete mixer, spra,yin~ is carried out at a temperature of 30C, of 24 g of composition no. 1 on a specimen of 20 kg of prilled ammonium nitrate whose ni~
trogen content is 33.5% and whose temperature is 30C~
A control specimen illustrating the prior art is prepared by treating 20 kg of ammonium nitrate with 20 g of a 30Y0 of stearylamine solution in oil by spraying at a temperature of 80 - 85C.
The two fertilizer speciments thus treated as well as an untreated specimen of 20 kg were tested by tests in an actual stack. After a month of storage under three tons load, the clumping was evaluated by weighing the lumps observed in each bag and by estima-ting their friability.
The untreated specimen showed a total setting solid corresponding to a clumping ratio of lOOY~ and the lumps are particularly hard.
The ratio of clumping of the specimen illustra ting the prior art is 15%, measured relative to the un-treated ammonium nitrat,e.
The specimen treated with composition no.
1 led to a ratio of 2% which signifies that no ferti-lizer dust is observed.
The results are reported in Table I.
Example 2-In a concrete mixer, is sprayed at a temperature of 30C, 24 g of composition no. 1 on a specimen of 20 kg of ammonium nitrate whose nitrogen titer is 26% and ' temperature 28C.
A specimen control illustrating the prior art _ 35 was prepared by spraying 20 g of a solution of fatty amine in 25% oil on 20 kg of ammonium nitrate. The i9~

spraylng was carried out at a temperature of 80C.
Another control specimen was prepared by spray-ing 8 g o~ surfactant based on monoalkanolamine tetra-alkylnaphthalene sulfonate in a wax in a ratio of 33.66, on 20 kg of ammonium nitrate. The latter spraying was carried out at a temperature of 95C.
The three fertilizer specimens thus treated were tested by trials in an actual stack, as described above.
The clumping ratio of the ammonium nitrate trea-ted with the amine solution is 15% measured relative toan untreated ammonium nitrate control of which the clum-ping ratio is 100%, which corresponds to a total set-ting solid.
The specimen control treated with monoethanol-amine tetraalkylnaphthalene sulfonate led to a clumping ratio of 14%.
The composition no. 1 led to a clumping ratio of 3%, the lumps being also very crumbly.
Example 3:
________ _ In a concrete mixer is sprayed, at a temperature of 30C on a specimen 20 kg of N.P.K. fertilizer 15/11/
22, 24 g of` the anti-clumping product of composltion no.
1.
The spraying is followed by a coating by means of 100 g of commercial clay. The concrete mixer is left to rotate f`or 5 minutes in order that the N.P.K. f`erti-lizer granules were uniformly coated.
The coating is followed by spraying of 32 g of heavy fuel.
A control specimen is prepared by coating 20 kg of r~.p.K. fertilizer in the same manner by means of 100 g of commercial clay, then a mixture of 8 g of surface active agent based on monoethanolamine tetraalkylnaph-thalene sulfonate in an aromatic oil in the ratio 35 of 70 - 30 and 32 g of` heavy fuel sprayed thereon.

2~i~3~3~

After an actual stacking test of 15 days, the clum-ping ratio of the fertilizer treated with the composi-tion no. 1 is 1.2% whereas that treated with monoethanol amine tetraalkylnaphthalene sulfonate in oil is 32% re-lative to a control specimen which was untreatedwhose setting solid was total, which corresponds to a clumping ratio of 100%.
The results are reported in Table I.
Example 4-10An anti-clumping composition called composition no. 2 is prepared by mixing the following constituents:
Solution B 26.~
Water 23.7 30% Soda solution 9.3 15 Dry extract sodium silicate ~6.4% and of ratio SiO2/Na20 = 2.1 42.6 100 .0 this anti-clum?ing cornposition having a dry extract of ~0%.
20There is sprayed into a concrete mixer 24 g of composition no. 2 on 20 kg of ammoniu~ nitrate whose nitrogen titer is 33.5% and whose temperature is 31C.
This specimen is sub~ected to a stacking test described in Example 1. The clumping ratio of the ammo-nium nitrate treated by composition no. 2 is 30% re-lative to an untreated control whose setting solid is total, which corresponds to a clumping ratio of 100%.
The results are reported in Table I.
Examples_5 and 6 An anti-clumping composition called composition no. 3 was prepared by mixing the following constituents:
Solution A 56.9 Water 10.4 35 30% Soda solution 5.1 1~6~Bfil:) Dry extract sodium silicate 46.4% and ratio SiOz/Na20 = 2.1 27.6 100.0 this anti-clumping composition havlng a dry extract of ~0%.
The ratio in dry matter:
sodium sulfonate sodium silicate is 2.
In the same way, an anti-clumping composition called composition no. 4 is prepared by mixing the following constituents:
Solution A 28.1 Water 14.8 30% Soda solution 2.5 Dry extract sodium silicate 46.4% and lS 2/ 2 S4.6 100 .0 This composition has a dry extract of 38.7%.
The ratio of dry matter:
sodium sulfonate sodium silicate is 0.5.
In the same way as in Example 1, compositions 3 and 4 were tested on ammonium nitrate whose nitrogen titer is 33.5%~
The results are reported in Table I.
Example 7.
Procedure was in the same manner as in Example 3 with the slight difference that there is no spraying of heavy fuel and, besides, that the treatments respective-ly uith clay and uith composition no. 1 are done in re-verse order.
There is also a difference, on the ~core of the amounts employed.
The results are reported in Table I.

~ ~6~
. . ~

Example 8-The procedure was in the sarne manner as Example 3, with the slight difference that the clay is replaced by talc.
The results are reported in Table I.
Example 9 In a concrete mixer, are sprayed at a tempera-ture of 20C, 20 g of the solution sodium silicate of ratio SiO2/Na20 = 3.S and dry extract equa].ling 35%, on an ammonium nitrate specimen whose nitrogen titer is 33.50,~.
This first spraying is followed by a second car-ried out at 70C, of 12 g of surfactant based on mono-ethanolamine dialkylnaphthalene sulfonate with a wax in the ratio 66 - 33.
A control specimen is prepared by spraying at a temperature of 80C, 20 g of a commercial solution at 25% of aminated oil on 20 kg of the same ammonium ni-trate.
The two fertilizer specimens thus treated are tested by tests in an actual stack.
The clumping ratio of the specimen treated by means of a sodium silicate solution and monoeth~nolamine dialkylnaphthalene sulfonate with a wax is 6% and that of the ammonium nitrate treated with aminated oil 9%
relative to a control of untreated ammonium nitrate whose clumping ratio is 100%, which corresponds to a to-tal setting solid.
The results are reported in Table I.
Exam~le 10: ~
____ ~_____ In a concrete mixer 9 iS sprayed, at the temper-ature of 20Ct 20 g of a sodium silicate solution of ra-tio SiO2/Na20 = 3.5 and of dry extract equal to 35%, on 20 kg of ammonium nitrate whose nitrogen titer is 33.5%.
This spraying is followed by another of 8 g of stearic acid, at a temperature of 70C on fertilizer i9~3~(`3 whose temperature is 30~C.
The so-treated nitrate i5 tested by actual stack-ing tests as described previously.
The clumping ratio of the thus-treated fertili-zer is 33% measured relative to an untreated ammonium nitrate control whose clumping ratio is 100%.
The results are reported in Table I.
Example 11:
____ ______ The following solution was prepared:
40 g of a 30% aqueous solution of a C12-C14 ox-yethylenated alcohol sulfate with 3 moles of ethylene oxide is mixed with 40 g of a sodium ~ilicate solution whose ratio SiO2/Na20 = 2.1 and dry extract extract equ-al 46,4%; then 20 g of water are added so as to obtain a homogenous solution of dry extract equal to 30%.
On 20 g of ammonium nitrate whose nitrogen ti-ter is 33.5,' and temperature 30C, are sprayed 20 g of the previously described solution.
The thus treated fertilizer is tested by tests in an actual stack as described previously.
The clumping ratio of the fertilizer thus treat-ed is 6% measured relative to a control of untreated am-monium nitrate whose clumping ratio is 100%.
The results are report0d in Table I.
Exam~le 12.
The following anti-clumping composition called composition no. 5 is prepared.
Solution B previously described 33.3 30% Soda solution 16.7 30 ~later 607 Potassium silicate dry extract 31.5% and ratio SiO2/K20 = 2.32 33 3 This anti-clumping composition has a dry extract _ 35 of 39%.

2~

In a concrete mixer, are sprayed 26 g of composition no. 5 at a tempera-ture of 20C on 20 kg of ammonium nitrate whose nitrogen titer is 33.5% and whose temperature reaches 31C.
The thus treated fertili~er was tested by tests in an actual stack as previously desc~ibed.
The clumping ratio of ammonium nitrate thus treated is 5% measured relative to an untreated control whose clumping ratio is 100%~ which corresponds to the total setting solid.
The results are reported in Table I.
Example 13~
The preparation of the monoethanolamine salt of naphthalene sulfonic acid polycondensed with formol. is described.
A solutiGn with 70% dry extract is prepared.
The following anti-clumping composition called composition no. 6 is prepared:

,7 ,, 12Ç;~36~3 Monoethanolamine salt of ~-naphthalene sulfonic acid polycondensed with 70' of formol 22.7 Water 22.7 5 30% Soda solution 9.1 Sodium silicate of a ratio SiO2/Na20 = 2.1 and dry extract equal ko 35% 45.5 In a concrete mixture is sprayed 24 g of compo-sition no. 6 at a temperature of 20C onto 20 kg ofammonium nitrate whose nitrogen titer is 33.5% and temp-erature 30C.
The fertilizer thus treated is tested by actual stack tests as described previously.
The clumping ratio of the thus treated ammonium nitrate is 24% measured relative to an untreated con-trol fertilizer whose clumping ratio reaches 100%, which corresponds to setting totally solid.
The results are recorded in Table I.
Example 14:
____ _._____ There is preparedan anti-clumping compo~itlon cal-led composition no.7 whose constitution is as follows:
Prevlously described solution A34.5 Water 11.2 25 30% Soda solution 4.1 Sodium silicate dry extract 46.4~
and ratio SiO2/Na20 = 2.1 _50.2 Composition no. 7 shows a dry extract of 40%.
In a concrete mixer spraying is carried out at a temperature of 30C, of 16 g of composition no. 7 on a specimen of 20 kg prilled ammoniu~ nitrate whose nitrogen content is 33.5% and whose temperature is A control sample illustrating the prior art is prepared by treating 20 kg of ammonium nitrate with 20 g ~ 31 of a 20% stearylamine in oil solution by spraying at a temperature of 80 - 85~C.
The two fertilizer speciments thus treated as well as an untreated 20 kg specimen were tested hy tri-als in an actual stack. After a month of storageunder a three ton load, the clumping was estimated by weighing the lumps observed in each bag an~ by evalua-ting their friability.
The untreated specimen shows a total setting so-lid corresponding to a clumping ratio of 100% and thelumps are particularly hard.
The clumping ratio of the specimen illustrating the prior art is 40% measured relative to the untreated ammonium nitrate.
The specimen treated with composition no. 1 led to a clumping ratio of 20~o~ the lumps being friable.
The results are recorded in Table I.
Example 15:
____ ______ In a concrete mixture is sprayed at a tempera-ture of 30C, a specimen of 20 kg of granulated N.P.K.fertilizer of the formula 15.12.24~ with 24 g Of compo-sition no. 7.
The spraying is followed by coating by means of 100 g of commercial clay. The rotation of the concret0 mixture for 5 minutes permits uniformity of coatlng of the N.P.K. granules.
This coating is followed by spraying with 32 g of heavy fuel.
A control sample is prepared by coating 20 kg of N.P.K. fertilizer by the same process with 100 g of commercial clay, then spraying a mixture of ~ g of sur-factant based on monoethanolamine tetra-alkalylnaphtha~
lene sulfonate in an aromatic oil in the ratio 70/30 and 32 g of heavy fuel.
~5 After an actual stacking test of 45 days, the clumping ratio of the fertilizer treated with composi~

C;~

tion no. 7 is 2% with very friable lumps, whereas that treated with monoethanolamine tetraalkylnaphthalene sul-fonate is 10% relative to an untreated control specimen whose setting solid is total, which corresponds to a clumping ratio of 100%. The results are recorded in Table I.
Example 16:
____ ______ An anti-clumping composition called composition no. 8 is prepared whose composition is as follows:
10 Previously described solution A6900 Water 10.2 30% Soda solution 4.1 Sodium silicate dry extract 46.4% and ratio SiO2/Na20 = 2.1 16.7 This composition has a dry extract of 40%.
In a concrete mixer at ambient temperature onto 20 kg of prilled ammonium nitrate whose nitrogen titer is 33.5%, is sprayed 26 g of composition no. 8.
A control specimen is prepared by coating 20 kg of this fertilizer with 8 g of surfactant based on mono-ethanolamine tetraalkylnaphthalene sulf`onate in a wax in the ratio 33:66 kept at the temperature of 80 - 85C
during the spraying.
This specimen is sub~ected to the static test described in Example 1. The clumping ratio of the ammonium nitrate treated by composition no. 8 is 34%
relative to an untreated control whose clumping ratio is 100%, which corresponds to setting solid.
The control specimen gives a clumping ratio 100%
Example 17:
____ ______ An anti-clumping composition called com`position no. 9 is prepared whose constitution is as follows:
Previously described solution A 51.7 - 35 Water 5.0 Sodium hydroxide solution 30% 4.1 Sodium silicate dry extract 39.6% and 2/ 2 2.1 _39.2 This composition has a dry extract of 40%.
In a concrete mixer is sprayed onto 20 kg of prilled ammonium nitrate, whose nitrogen titer is 33.5% and temperature 38C is sprayed 30 g of composi tion no. 9.
A control specimen is prepared illustrating the prior art by spraying 24 g of a 20% fatty amine solution in oil. The spraying is done at a temperature of 80C.
It is followed by coating with 500 g of kieselghur. The rotation of the concrete mixture is continued for 5 minutes to ensure homogeneity of treatment.
After the stacking test similar to that descri-bed in Example 14, the fertilizer treated with composi-tion no. 9 has a clumping ratio of 45%, with very crum-bly lumps, comparatively to an untreated control whose clumping ratio is 100/~.
The clumping ratio of the fertilizer treated with the aminated oil is 100%. In addition it is ex tremely dusty.
Example 18:
___________ In a concrete mixer is sprayed on 20 kg of gran-ulated ammonium nitrate whose nitrogen titer is 26% Of temperat~lre 40C, 28 g of composition no. 9 at ambient temperature.
A control specimen is prepared by coating in the same way 20 kg of'this fertilizer with 24 kg of aqueous solution adjusted to 35% dry extract of a surfactant ba-sed on sodium dialkylnaphthalene sulfonate in aqueous solution with 35% dry matter. This spraying is preceded by coating by means of 100 g of commercial talc.
After an actual stacking test of 1 month, the fertilizer treated with the composition no. 9 shows a clumping ratio of 70% with crumbly lumps, ~ ~,,q~ 3~6~) relative to an untreated fertilizer whose clumping ratio is 100%, with hard lumps corresponding to a total set-ting solid.
Under these conditions, the control specimen gives a clumping ratio of 100% and is slightly dusty.
Exam~le 19:
___._ ______ Procedure is similar in Example 15, with the slight difference that formula of the fertilizer is 17x17x17 and that the composition no. 9 replaces compo-sition no. 7.
After an actual stacking test of 84 days, theclumping ratio of the fertilizer treated with composi-tion no. 9 is 6.5% with crumbly lumps, that treated with the tetraalkylnaphthalene sulfonate is 28% in comparison with an untreated control specimen whose clumping ratio is 100%, which corresponds to a total setting solid.
Example 20-An anti-clumping composition called composition no. 10 is prepared whose composition was as follows:
20 Previously described solution A 42.0 Sodium hydroxide solution 30~0 4.0 Sodium silicate dry extract 35% and ratio SiO2/Na20 = 3.5 54.0 This composition having a dry extract of 39%.
There is sprayed in a concrete mixer on 20 kg of low density nitrate of nitrogen content 33.5%, 40 g of composition no. 10 at ambient temperature.
A specimen illustrating the prior art is prepared by spraying at 80C 14 g of microcrystalline wax of melting point 65-70~C, followed by spraying of 14 g of a fatty amine at a temperature of 80C.
After stacking, as described in Example 14, the treated fertilizer with the composition no. 10 has a 3~Bt`~C~

clumping ratio of 50% with friable lumps, with respect to the specimen of untreated fertilizer which gives a clumping of 100%, corresponding to total setting solid.
The fertilizer treated with the association of wax-fatty amine has a clumping ratio of 95~0 with very hard lumps.
Example 21:
____ ______ The anti-clumping composition called composition no. 11 is prepared constituted in the following manner:
10 Previously described solution A 36.5 Water 27.8 Soda solution 30% 7.1 Pentahydrated sodium metasilicate containing 42.5% oE water and of 15 ratio Si2/Na2 = 1 ~8 6 Procedure is as in Example 14 with the slight dif-ference that the 16 g of composition no. 17 are replaced by 20 g of composition no. 11.
The untreated specimen has a total setting solid corresponding to a clumping ratio 100% and the clumps are particularly hard.
The clumping ratio of the specimen illustrated in the prior art is 40% measured relative to the untreated ammonium nitrate.
The specimen treated with composition no. 7 leads to a clumping ratio of 20% the lumps being friable.
Exam~le 22 ___ _____ In a concrete mixer is loaded 20 kg of granuls-ted 3x17 N.P.K., of temperature 40C and with stirring and 16 g of a solution of sodium silicate whose ratio - . SiO2/Na20 = 2.1 and whose dry ex~ract has ~een brough-t to 40% i8 sprayed thereon.

1~i9~360 There i8 then dusted thereon,still with stirring 60 g of clay and it is sprayed immediately with 40 g of solution C taken to 80C. The concrete mixer is left to rotate for 5 further minutes and then placed in a bag.
The fertilizer is placed in a stack with a bag of un-treated fertilizer under 2 t load.
After 2 months under pressure, the stack is dismantled and the bags are opened.
The fertilizer treated as described above shows just a small friable lump representing 15% of the weight of fertilizer.
The untreated fertilizer is in the form of a hard lump. The clumping is lO0~.
Example 23:
___ ______ In a concrete mixer is charged 20 kg of ammo-nium nitrate whose titer has been brought to 33.5,' by 4%
of ammonium sulfate, the fertilizer being at 35C and stirred. 20 g of a solution of sodium silicate of ratio SiO2/Na20 = 3.5 and whose dry extract has been brought to 35/0 is sprayed thereon. Under stirring is then sprayed 20 g of solution C brought to 80C. The concrete mixer i8 l~ft to rotate for 5 additional min-utes and the fertillz0r placed in bags. A control trea~-ment of the prior ar-t is carried out by spraying in the same mann~r 40 g of oil containing 20% stearylamine pre-viously brought to 80C. The fertilizer according to the invention, and the fertilizer according to the con-trol treatmentt and the untreated fertilizer are placed in bags, and the bags stacked under a 3 t load.
After being in a stack for 2 months the untreat~
ed fertilizer bag is a hard block which only breaks af-ter several falls, the fertilizer treated with the amine in oil shows a rather hard lump representing 60% of the fertilizer present, and the fertilizer treated according to the invention only has a lump of 50% which is rather friable.

~2~

Example 24:
____ ______ Procedure is as in Example 22 but the solut,ion C
is replaced by solution D. The control specimen of the prior art i5 formed by dusting onto the 20 kg of 3x17 N.P.K., 140 g of a clay dosed with 3% of stearylamine and by spraying 40 g of heavy fuel no. 2 thereon pre-viously heated to 80C.
After removing from the stack the fertilizer ac-cording to the invention is not clumped and flows freely after opening the bags, the fertilizer according to the prior art is clumped to more than 40% whilst the untrea-ted fertilizer is a real hard block.

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Claims (18)

WHAT IS CLAIMED IS:

1. In an anticlumping process of non-powdery salts and fertilizers comprising spraying of an anti-clumping agent onto the salts or the fertilizers to be treated, the improvement comprising:
- selecting, as a first anticlumping agent, an aqueous solution of alkali silicate whose dry matter content is from 15 to 60% by weight and, as a second anticlumping agent, an anionic surfactant in the form of an alkali, alkaline-earth or amine salt in aqueous or oily solution.
- spraying onto the constituent particles of the salt or fertilizer to be treated, after drying and before storage of the particles at a moment at which they have acquired almost the whole of their final mechanical properties, the said first and second anti-clumping agents either simultaneously in the form of an aqueous solution or an emulsion or successively, the used amount of the first anticlumping agent being se-lected in such a way that it constitutes 0.6 to 1.5 per thousand by weight with respect to the said salt or fertilizer to be treated.

2. Process according to Claim 1, wherein the first anticlumping agents is an alkali silicate having a ratio SiO2/Na2O from 2 to 4.

3. Process according to Claim 1, wherein the second anticlumping agent is an alkylarylsulfonic sur-factant in the form of an alkali, alkaline-earth, alkylamine, cycloalkylamine or aromatic amine salt.

4. Process according to Claim 1, wherein the second anticlumping agent is selected from the group consisting of alkali, alkaline-earth, alkylamine, cycloalkylamine and aromatic amine polyalkylnaphtalene sulfonate.

5. Process according to Claim 1, wherein an amount of 0.2 to 8 per thousand by weight, with respect to the said salt or fertilizer to be treated, of oil or of fuel is associated with the first or the second anticlumping agent or with the solution or the emulsion containing both of them.

6. Process according to Claim 1, wherein an amount of 1 to 35 per thousand by weight, with respect to the said salt or fertilizer to be treated, of an inert mineral coating agent selected from the group consisting of talc, kaolin, kieselguhr, clays, infuso-rial earths and silicoaluminates, is associated with the first or the second anticlumping agent or with the solution or the emulsion containing both of them.

7. Process according to Claim 1, wherein an amount of 0.2 to 8 per thousand by weight, with respect to the said salt or fertilizer to be treated, of oil or fuel as well as an amount of 1 to 35 per thousand by weight, with respect to the said salt or fertilizer to be treated, of an inert mineral coating agent selected from the group consisting of talc, kaolin, kieselguhr, clays, infusorial earths and silicoaluminates, are associated with the first or the second anticlumping agent or with the solution or the emulsion containing both of them.

8. Process according to Claim 1, wherein the fertilizer to be treated is ammonium nitrate having a nitrogen titer comprised between 33.5 and 34.8%, a moisture content comprised between 0.1 and 0.4% and a temperature less than 40°C.

9. Process according to Claim 1, wherein the fertilizer to be treated is ammonium nitrate having a nitrogen titer less than 33.5%, a moisture content com-prised between 0.1 and 1% and a temperature less than 50°C.

10. Process according to Claim 1, wherein the fertilizer to be treated is N.P.K. having a moisture comprised between 0.1 and 3% and a temperature less than 80°C.

11. Anticlumping composition for non powdery salts or fertilizers consisting of an aqueous solution or of an emulsion and comprising a first anticlumping agent consisting of an alkali silicate whose dry matter content is from 15 to 60% by weight and a second anti-clumping agent consisting of an anionic surfactant in the form of an alkaline, alkaline-earth or amine salt, the respective proportions by weight of dry matter of the first and of the second anticlumping agent being from 10/90 and 90/10.

12. Anticlumping composition according to Claim 11 comprising a fuel or an oil.

13. Anticlumping composition according to Claim 11 comprising an inert mineral coating agent selected from the group consisting of talc, kaolin, kieselguhr, clays, infusorial earths and silico-aluminates.

14. Anticlumping composition according to Claim 11 in the form of an "oil-in-water" emulsion and consisting of - 1.6 to 21.6% by weight on dry matter of alkali or amine silicate, - 21.6 to 1.6% by weigh-t on dry matter of sur-factant, - 40 to 60% by weight of fuel, wax or oil, the complement to 100 being constituted by water.

15. Anticlumping composition according to Claim 11, wherein the first anticlumping agent is an alkali silicate having a ratio SiO2/Na2O from 2 to 4.

16. Anticlumping composition according to Claim 11, wherein the surfactant is an alkylaryl sulfonic surfactant in the form of alkali, alkaline-earth or alkylamine, cycloalkylamine, aromatic amine salt.

17. Anticlumping composition according to Claim 11, wherein the surfactant is selected from among alkali-, alkaline-earth-, alkylamine-, cycloalkylamine-and aromatic amine-polyalky]naph-talene sulfonates.

18. Anticlumping composition according to Claim ll, wherein the surfactant is selected from the group consisting of mono-, di-, tri-, tetra-, propyl-or isopropyl-, butyl- or isobutyl-naphtalene and methylnaphtalene sulfonates.