Abstract: Preparation of granules by making nuclei grow, in a fluidized bed, by causing a liquid material to solidify thereon. The liquid material is sprayed in the bed upwards, with the aid of a spraying device provided with a central channel through which the liquid material is supplied, and a channel concentric therewith carrying a powerful gas stream, with the liquid material contacting the gas stream and being carried with the gas stream to a dilute zone where the growth of the nuclei takes place, which zone is created by the gas stream and is completely within the fluidized bed. The liquid material is made to come out of the central channel as a virtually closed, conical film, with a thrust exceeding the thrust of the gas stream, and this film is nebulized to very fine droplets with the aid of the gas stream.In this process a very small amount of high-energetic gas is needed, while no agglomeration occurs in the bed.

Abstract: Preparation of granules by making solid nuclei grow in a fluidized bed, by causing a liquid material to solidify thereon, the liquid material being introduced into the bed from the bottom upwards with the aid of a feeding device provided with a central channel through which the liquid material is supplied and a channel concentric therewith through which a powerful gas stream is supplied, which creates a rarefied zone in the bed above the feeding device, wherein the liquid material is made to exit from the central channel into the rarefied zone as a virtually closed, conical film, nuclei from the bed are carried through the film with the aid of the powerful gas stream and next, during transport of the so moistened nuclei through the rarefied zone, the liquid material taken up by the nuclei is allowed to solidify. By this process only a small amount of high-energetic gas is required, while very little agglomeration and dust formation occurs.

Abstract: A process for determining the composition of an aqueous solution of ammonia and carbon dioxide from which ammonium carbamate or ammonium carbonate crystallizes out upon cooling to below the saturation temperature. The density and the saturation temperature of the solution are measured, and the ammonia, carbon dioxide, and water composition is determined by reference to densities and saturation temperatures of aqueous solutions of ammonia and carbon dioxide of known composition. The composition thus determined can be used to effect control over the composition of such aqueous solutions.

Abstract: A method and apparatus for determining the saturation temperature of a solution containing a dissolved substance, the crystals of which are optically anisotropic. The solution is placed in an optical measurement vessel under conditions wherein crystals of said substance are present, and the temperature of said crystal containing solution is gradually increased to at least the temperature at which all of the crystals dissolve. The temperature of the solution is continuously measured. Simultaneously with the temperature increase, a beam of linearly polarized light is directed into the optical measurement vessel in a manner such that it is transmitted through said solution; the transmitted beam of light, after having passed through the solution, is directed through a light polarizing analyzer having a direction of polarization normal to that of said beam of light; and at least a portion of any light transmitted through said analyzer is directed to a light measuring photodetector.

Abstract: Separating Ca(NO.sub.3).sub.2.4H.sub.2 O from a nitrophosphate digestion liquor by crystallization, wherein Ca(NO.sub.3).sub.2.4H.sub.2 O seeding material with a particle size smaller than 100 .mu.m is added to this liquor at a temperature of 0.degree.,1.degree.-2.degree. C. lower than the saturation temperature, the resulting liquor is batchwise cooled, and the Ca(NO.sub.3).sub.2.4H.sub.2 O crystallized out is separated from the cooled liquor.The Ca(NO.sub.3 ).sub.2.4H.sub.2 O is substantially crystallized out without excessive cooling as very coarse and uniform particles which can be easily separated out.

Abstract: A process for the preparation of urea from ammonia and carbon dioxide at an elevated temperature and pressure having a reaction zone and a stripping zone. In the reaction zone, carbon dioxide and a portion of the ammonia are converted to ammonium carbamate, and a portion of the ammonium carbamate is converted to urea, the combined conversions resulting in a net formation of heat. In the stripping zone, a urea product stream containing unconverted ammonium carbamate is heated by heat exchange with the reaction zone to decompose a portion of the ammonium carbamate. In the reaction zone, the conversion of ammonium carbamate into urea is continued until the quantity of urea formed is at least 50 percent of that quantity of urea that would be obtained at equilibrium under the reaction conditions present in the reaction zone.

Abstract: An improved process for the preparation of urea from carbon dioxide and excess ammonia at elevated temperature and pressure. The urea solution from the urea synthesis zone is heated and stripped at an elevated pressure to decompose a portion of the ammonium carbamate contained therein and the ammonium and carbon dioxide containing off-gas produced is condensed in a first condensation zone. The stripped urea solution is heated at a reduced pressure in a decomposition zone to decompose a further portion of ammonium carbamate, and the ammonia and carbon dioxide containing off-gas thereby produced is condensed in a second condensation zone to form an aqueous ammonium carbamate solution.

Abstract: An improved process and apparatus for the removal of ammonium carbamate from an aqueous urea solution wherein the aqueous urea solution is introduced into a stripping zone and caused to flow down a heat exchange wall as a thin film while being heated and contacted in counter-current relation with a gaseous stripping agent. The aqueous urea solution, while being stripped, is heated for at most 5 seconds at a temperature in the range of from 180.degree.-195.degree. C. and thereafter cooled to a temperature of from 155.degree.-170.degree. C.

Abstract: Process for preparing pure silicon dioxide from a hexafluorosilicic acid solution by controllably and vigorously admixing, stirring or blending a hexafluorosilicic acid solution with a quantity of ammonium hydroxide solution amounting to about 40 to about 75 percent by weight of the quantity stoichiometrically required for the converting hexafluorosilicic acid to ammonium fluoride and silicon dioxide to thereby form a reaction mixture and a precipitate therein; separating out this precipitate; treating the precipitate-free liquid with ammonium hydroxide and then recovering the pure silicon dioxide. The silicon dioxide is pure enough to be useful as a catalyst support or as a substitute for quartz.

Abstract: An improved process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions thereof by hydrolyzing the urea, and thereafter desorbing ammonia and carbon dioxide. The dilute solution containing urea is passed into the top portion of a reaction column and caused to flow downward and countercurrent to a heating and stripping gas while maintaining the reaction column at a pressure of between about 10 and 30 bar, and a top column temperature of between about 170.degree. and 220.degree. C. and a bottom column temperature of between about 180.degree. and 230.degree. C. The resulting liquid stream removed from the bottom of the reaction column, comprised of a substantially urea-free aqueous solution of ammonia and carbon dioxide, is introduced into a desorption zone wherein, at a pressure of between about 1 and 5 bar, ammonia and carbon dioxide are removed therefrom.

Abstract: A process for preparing thermally stable ammonium nitrate-containing granules having high bulk density, high impact resistance, high crushing resistance, and little or no tendency to cake by spraying a liquid composition containing at most 15% by weight water, a stabilization agent, ammonium nitrate and other components into a fluidized bed of ammonium nitrate seed particles thereby forming granules and recovering the thus formed ammonium nitrate-containing granulated product.

Abstract: Storage-stable nitrogen-phosphorous-potassium fertilizer granules and prills are made by adding to a molten or aqueous solution mixture of ammonium nitrate and ammonium phosphate, a particulate potassium salt, typically potassium chloride, in which the particles have an average size no greater than 55 microns and less than 1% by weight of the particles are larger than 150 microns. The potassium salt is added without the need for preheating and at a temperature of between 5.degree. and 40.degree. C. to the mixture where it is simultaneously converted. The resulting mixture is granulated or prilled into NPK fertilizer particles.

Abstract: A method for producing urea prills by passing molten droplets of substantially water free urea downwardly through a cooling zone countercurrent to a cooling gas. A dispersion of crystalline particles is maintained in at least a portion of the cooling zone, the crystalline particles having average dimensions of between 2 and 10 microns and being dispersed in the cooling gas in a quantity of between about 8 and 25 mg per m.sup.3 of the cooling gas at ambient temperature and pressure, whereby urea prills, built up of relatively small crystallites with random orientation having improved impact strength are formed.

Abstract: Ammonium orthophosphate products are prepared by reacting ammonia and phosphoric acid together at high speed under vigorous mixing conditions by spraying the reactants through a two-phase, dual coaxial mixer/sprayer and separately controlling the supply and axial outflow rate of the phosphoric acid at 1 to 10 m/sec. and the outflow rate of ammonia at 200 to 1000 m/sec. (N.T.P.). Thorough mixing and a homogeneous product is obtained by directing the outflow spray into a coaxial cylindrical reaction chamber of a specified size with respect to the diameter of the outermost duct of the sprayer/mixer. The product may be granulated on a moving bed of granules and adjusted in respect of the NH.sub.3 to H.sub.3 PO.sub.4 content by changing the concentration of the phosphoric acid and/or supplying additional ammonia to the granulation bed.

Abstract: Ammonium orthophosphate products are prepared by reacting ammonia and phosphoric acid together at high speed under vigorous mixing conditions by spraying the reactants through a two-phase, dual coaxial mixer/sprayer and separately controlling the supply and axial outflow rate of the phosphoric acid at 1 to 10 m/sec. and the outflow rate of ammonia at 200 to 1000 m/sec. (N.T.P.). Thorough mixing and a homogeneous product is obtained by directing the outflow spray into a coaxial cylindrical reaction chamber of a specified size with respect to the diameter of the outermost duct of the sprayer/mixer. The product may be granulated on a moving bed of granules and adjusted in respect of the NH.sub.3 to H.sub.3 PO.sub.4 content by changing the concentration of the phosphoric acid and/or supplying additional ammonia to the granulation bed.

Abstract: An improved process for the preparation of urea from carbon dioxide and ammonia at elevated temperature and pressure whereby unconverted ammonia, substantially free of carbon dioxide and water is recovered from a urea and ammonium carbamate containing liquid process stream. An urea and ammonium carbamate containing process stream is expanded to a pressure of between about 1 and 25 kg/cm.sup.2 absolute and heated, thereby decomposing ammonium carbamate and forming a gas mixture containing ammonia, carbon dioxide and water vapor.

Abstract: Unreacted free ammonia and ammonium carbamate are removed from a urea synthesis solution efficiently by first heating the solution up to 205.degree.-250.degree. C and then, in a second, separate step, stripping the heated solution with a stripping gas but under adiabatic conditions to remove the unreacted materials. The process is applied as an integral part of a continuous urea preparation.

Abstract: Mineral-enriched urea prills for addition to maize silage are prepared using conventional urea prilling equipment by rapidly mixing a urea melt with a mineral enrichment composition containing up to 22% weight of sodium chloride in a rapid manner such that at most only about one-third of the total sodium chloride content is dissolved, the balance remaining in suspension, mixing typically requires no more than about 7 seconds, then the melt is sprayed to prills and cooled.

Abstract: An improved method for spraying molten material in order to obtain solidified grains or prills. Molten material, such as NPK-fertilizer is fed into a symetrical rotating reservoir which rotates about a vertical axis and whose upright walls are provided with apertures for spraying. The interior of the rotating reservoir accommodates a member provided with blades, which member rotates at a speed different from that of the reservoir. The sprayed molten material cools while falling to form solid round prills. The blades inside the reservoir rotate at a speed at least 1.5 times greater than the speed of rotation for the reservoir.

Abstract: Ammonium carbamate is decomposed and removed in the form of its gaseous components by contacting a urea synthesis solution comprising the carbamate with a stripping gas, such as carbon dioxide, the countercurrent stripping conducted at adiabatic conditions in the stripper unit. Urea synthesis solution to be treated is supplied at higher pressures and temperatures, at least 205.degree.C and at a pressure of at least 225 atm. Conveniently, the decomposition of the ammonium carbamate and the removal of the liberated gases are carried out at these temperatures and pressures so that the stripper is operative under the same conditions as well.