CA1192413A - Process for manufacturing granular compound fertilizers - Google Patents
Process for manufacturing granular compound fertilizersInfo
- Publication number
- CA1192413A CA1192413A CA000421902A CA421902A CA1192413A CA 1192413 A CA1192413 A CA 1192413A CA 000421902 A CA000421902 A CA 000421902A CA 421902 A CA421902 A CA 421902A CA 1192413 A CA1192413 A CA 1192413A
- Authority
- CA
- Canada
- Prior art keywords
- slurry
- process according
- phosphoric acid
- ammonia
- fertilizer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05B—PHOSPHATIC FERTILISERS
- C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Pest Control & Pesticides (AREA)
- Fertilizers (AREA)
Abstract
SPECIFICATION
Title of the Invention:
A Process for Manufacturing Granular Compound Fertilizers Abstract of the Disclosure:
A process for manufacturing granular compound feritilizers wherein phosphoric acid, sulfuric acid or nitric acid or a mixture thereof is reacted with ammonia in a tubular reactor, the resulting reaction solution is concentrated to obtain a high temperature slurry having a liquid content of 40 - 90% by volume in a mixing tank, the high temperature slurry is then sprayed into a granu-lation zone of a spouted bed granulation apparatus or fluidized granulation apparatus to cause the thus-sprayed slurry to stick to priming particles floating in the granulation zone, thereby forming enlarged granules.
Title of the Invention:
A Process for Manufacturing Granular Compound Fertilizers Abstract of the Disclosure:
A process for manufacturing granular compound feritilizers wherein phosphoric acid, sulfuric acid or nitric acid or a mixture thereof is reacted with ammonia in a tubular reactor, the resulting reaction solution is concentrated to obtain a high temperature slurry having a liquid content of 40 - 90% by volume in a mixing tank, the high temperature slurry is then sprayed into a granu-lation zone of a spouted bed granulation apparatus or fluidized granulation apparatus to cause the thus-sprayed slurry to stick to priming particles floating in the granulation zone, thereby forming enlarged granules.
Description
Background of the Invention:
l. Field of the Invention:
This invention relates to a process for manufac-turing a granular compound fertilizer.
l. Field of the Invention:
This invention relates to a process for manufac-turing a granular compound fertilizer.
2. Description of the Prior Art:
It has been known to the public to prepare a solution o-f an ammonium phosphate, ammonium sulfate or a mixture thereof, which serves as a raw material for granular compound fertilizers, -from ammonia and phosphoric acid or sulfuric acid or a mixture of these acids while making use of a tubular reac-tor. Reference may be made, for example, to a report written by B. R. Parker, M. N.
Norton and D. G. Salladay (reported at FAI-IFDC Seminar 1977 in New Delhi, India). Compared with carrying out the above reaction in a neutralizing reaction tank equipped with an agitator, the above method has such merits that the reactor is simple in structure and easy in maintenance and the reaction heat may be effectively utilized -for the evaporation of water and the granulation and drying operations .
The thus-obtained solution is then fed to a drum-shaped granulator or blunger, mixed with a large quantity of recycled solid particles as well as, optionally another solid fertilizer substance and/or solid diluent
It has been known to the public to prepare a solution o-f an ammonium phosphate, ammonium sulfate or a mixture thereof, which serves as a raw material for granular compound fertilizers, -from ammonia and phosphoric acid or sulfuric acid or a mixture of these acids while making use of a tubular reac-tor. Reference may be made, for example, to a report written by B. R. Parker, M. N.
Norton and D. G. Salladay (reported at FAI-IFDC Seminar 1977 in New Delhi, India). Compared with carrying out the above reaction in a neutralizing reaction tank equipped with an agitator, the above method has such merits that the reactor is simple in structure and easy in maintenance and the reaction heat may be effectively utilized -for the evaporation of water and the granulation and drying operations .
The thus-obtained solution is then fed to a drum-shaped granulator or blunger, mixed with a large quantity of recycled solid particles as well as, optionally another solid fertilizer substance and/or solid diluent
- 3 -into granules, thereby providing a granular subs~ance having a water content of 2 - 5% by weight. This granular substance is thereafter dried with hot air in a rotary drier and subjected to classification in a classifier, thereby obtaining a final product, i.e., compound -Eertilizer of a desired particle size range. Excessively large particles are recycled to the granulator after pulverization and excessively small particles are recycled to the granulator as they are.
The above process generally requires making the quantity o~ solid particles recycled to the granulation apparatus 2 - 8 times that of the final product drawn out of the system in order to maintain the granulator and rotary drier under good operation conditions with respect to the granulatability of each compound fertilizer or the water or energy balance in the granulation system? although the above figures vary depending on the components contained in the compound fertilizer. Thus, it is generally required to recycle to the recycling line even a part of particles oE the desired particle size which are obtained in the classifier.
Summary of the Invention:
An object of this invention is to provide an improved process for efficiently manufacturing a granular compound fertilizer which contains at least -two agronomically ~2~
effective components selected from N (nitrogen), P (phosphor) and K (potassium).
According to this invention, the following process for manufacturing a granular compound fertilizer is provided:
A process -for manu~acturing a granular compound fertilizer containing at least two agronomically ef-fective components selected form N, P and K, which comprises reacting phosphoric acid, sulfuric acid or nitric acid or a mixture thereof and ammonia in a tubular reactor to form a solution containing diammonium hydrogenphosphate, ammonium dihydro-genphosphate, ammonium sulfate, ammonium nitrate or a mixture thereof; introducing the solution into a mixing tank and either evaporating the water contained therein to obtain a high temperature slurry having a liquid content of 40 - 90% by volume or evaporating the water contained therein and, at the same time, mixing a solid -fertilizer substance or solid diluent having particle sizes of 50 -1,000 ~m or a molten liquid or aqueous solution of a fertilizer substance with the solution to obtain a high temperature slurry having a liquid content of ~0 - 90% by volume spraying the thus-obtained high temperature slurry into the spacing of a granulation zone of a spouted bed granulation apparatus or fluidized bed granulation apparatus, thereby causing the thus-sprayed slurry to stick to priming particles floating in the spacing and thus forming enlarged granules; and drying and/or cooling the thus-enlarged granules.
~Z~
Brief Descrlption of the Drawing:
/ The accompanying drawing is a flow sheet illus-trating one embodiment of the invention.
Detailed Description of the Invention:
In a process according to this invention, ammonia and phosphoric acid, nitric acid, sulfuric acid or a mixture thereof are reacted in a tubular reactor. As an acid to be reacted with ammonia, it is preferred to employ phosphoric acid or a mixed acid of phosphoric acid and nitric acid or sulfuric acid. These acids and their proportions can be selected in accordance with the agronomica~ly effec~ive components contained in each intended compound fertilizer and the concentrations thereof.
Where phosphoric acid or a mixed acid of phosphoric acid and another acid is used, the resulting ammonium phosphate has maximum solubility when its molar ratio of ammonia to phosphoric acid is 1.~ to 1. If the molar ratio exceeds 1.4 to 1, the solubility of the ammonium phosphates drops abruptly and solid ammonium phosphates deposit, resulting in the clogging of the tubular reactor. Accord-ingly, it is desirable to maintain the molar ratio of ammonia to phosphoric acid in a tubular reactor within 1.3 - 1.6 to 1, particularly, within 1.3 - 1.5 to 1. Ammonia, which is reacted further with phosphoric acid, is added in a subsequent step as will be described later in this specifi-cation.
A tubular reactor is similar to a short piping in its structure and therefore, it has a very small volume.
It is thus unsuitable to employ such a tubular reactor for adding and mixing a solid, molten liquid or aqueous solution to and with a solution of ammonium phosphates J
ammonium sulfate or ammonium nitrate resulting from a reaction between ammonia and the above-described acid.
Therefore, a reaction mixture ~ormed in the tubular reactor is then introduced into a mixing tank, where it is reacted further with ammonia in order to increase the molar ratio of ammonia to phosphoric acid further. The water is caused to evapo~ate from the reaction mixture owing -to its sensible heat and reaction heat given off in the mixing tank. It is unnecessary to add that it is also possible to heat the mixing tank with steam and to evaporate the water if no sufficient heat quantity is available for the evaporation of the water from the reaction mixture. Furthermore, it is also possible to add while stirring various kinds of fertilizer substances in the form of a solid, molten liquid or aqueous solution to the reaction mixture in order to adjust the proportion of each component in ~he intended compound fertilizer and its concentration in the mixing tank. It may be feasible to add a solid diluent together with such fertilizer substances or as their substituent.
The particle sizes of these solids should range from 50 -1,000 ~m.
The liquid content of the thus-formed slurry ranges ~0 - 90~ by volume, and preferably, 40 - 60~ by volume. If the liquid content does not reach 40% by volume, it is di-fficult to achieve smooth transportation of the slurry -from the mixing tank to the granulation apparatus by means of a pump. On the other hand, if the water content of the slurry exceeds 30~ by volume, it is necessary to have more water evaporate in the granulation apparatus, thereby leading to an increased energy demand. Such a high water content is accompanied by another drawback in that the water content of the granular substance to be obtained will be high and a separate drier will be required.
Although fine solid particles are contained in the thus-obtained high temperature slurry, these solid particles have particle sizes within the above range and are uniformly dispersed in the slurry, thereby making it possible to feed the slurry to a spouted bed or fluidized bed granulation apparatus, which will be described below, by means of a pump. Owing to the nature of the slurry, spray nozzles of the granulation apparatus will be protected from clogging. It is pre-ferred to conduct the agitation of the reaction mixture in the mixing tank at a speed of 150 -500 r.p.m. It is generally preferred to maintain the slurry at 80 - 130C in the mixing tank, although it varies depending on the composition and the like of the intended compound fertilizer. The residence time of the slurry in the mixing
The above process generally requires making the quantity o~ solid particles recycled to the granulation apparatus 2 - 8 times that of the final product drawn out of the system in order to maintain the granulator and rotary drier under good operation conditions with respect to the granulatability of each compound fertilizer or the water or energy balance in the granulation system? although the above figures vary depending on the components contained in the compound fertilizer. Thus, it is generally required to recycle to the recycling line even a part of particles oE the desired particle size which are obtained in the classifier.
Summary of the Invention:
An object of this invention is to provide an improved process for efficiently manufacturing a granular compound fertilizer which contains at least -two agronomically ~2~
effective components selected from N (nitrogen), P (phosphor) and K (potassium).
According to this invention, the following process for manufacturing a granular compound fertilizer is provided:
A process -for manu~acturing a granular compound fertilizer containing at least two agronomically ef-fective components selected form N, P and K, which comprises reacting phosphoric acid, sulfuric acid or nitric acid or a mixture thereof and ammonia in a tubular reactor to form a solution containing diammonium hydrogenphosphate, ammonium dihydro-genphosphate, ammonium sulfate, ammonium nitrate or a mixture thereof; introducing the solution into a mixing tank and either evaporating the water contained therein to obtain a high temperature slurry having a liquid content of 40 - 90% by volume or evaporating the water contained therein and, at the same time, mixing a solid -fertilizer substance or solid diluent having particle sizes of 50 -1,000 ~m or a molten liquid or aqueous solution of a fertilizer substance with the solution to obtain a high temperature slurry having a liquid content of ~0 - 90% by volume spraying the thus-obtained high temperature slurry into the spacing of a granulation zone of a spouted bed granulation apparatus or fluidized bed granulation apparatus, thereby causing the thus-sprayed slurry to stick to priming particles floating in the spacing and thus forming enlarged granules; and drying and/or cooling the thus-enlarged granules.
~Z~
Brief Descrlption of the Drawing:
/ The accompanying drawing is a flow sheet illus-trating one embodiment of the invention.
Detailed Description of the Invention:
In a process according to this invention, ammonia and phosphoric acid, nitric acid, sulfuric acid or a mixture thereof are reacted in a tubular reactor. As an acid to be reacted with ammonia, it is preferred to employ phosphoric acid or a mixed acid of phosphoric acid and nitric acid or sulfuric acid. These acids and their proportions can be selected in accordance with the agronomica~ly effec~ive components contained in each intended compound fertilizer and the concentrations thereof.
Where phosphoric acid or a mixed acid of phosphoric acid and another acid is used, the resulting ammonium phosphate has maximum solubility when its molar ratio of ammonia to phosphoric acid is 1.~ to 1. If the molar ratio exceeds 1.4 to 1, the solubility of the ammonium phosphates drops abruptly and solid ammonium phosphates deposit, resulting in the clogging of the tubular reactor. Accord-ingly, it is desirable to maintain the molar ratio of ammonia to phosphoric acid in a tubular reactor within 1.3 - 1.6 to 1, particularly, within 1.3 - 1.5 to 1. Ammonia, which is reacted further with phosphoric acid, is added in a subsequent step as will be described later in this specifi-cation.
A tubular reactor is similar to a short piping in its structure and therefore, it has a very small volume.
It is thus unsuitable to employ such a tubular reactor for adding and mixing a solid, molten liquid or aqueous solution to and with a solution of ammonium phosphates J
ammonium sulfate or ammonium nitrate resulting from a reaction between ammonia and the above-described acid.
Therefore, a reaction mixture ~ormed in the tubular reactor is then introduced into a mixing tank, where it is reacted further with ammonia in order to increase the molar ratio of ammonia to phosphoric acid further. The water is caused to evapo~ate from the reaction mixture owing -to its sensible heat and reaction heat given off in the mixing tank. It is unnecessary to add that it is also possible to heat the mixing tank with steam and to evaporate the water if no sufficient heat quantity is available for the evaporation of the water from the reaction mixture. Furthermore, it is also possible to add while stirring various kinds of fertilizer substances in the form of a solid, molten liquid or aqueous solution to the reaction mixture in order to adjust the proportion of each component in ~he intended compound fertilizer and its concentration in the mixing tank. It may be feasible to add a solid diluent together with such fertilizer substances or as their substituent.
The particle sizes of these solids should range from 50 -1,000 ~m.
The liquid content of the thus-formed slurry ranges ~0 - 90~ by volume, and preferably, 40 - 60~ by volume. If the liquid content does not reach 40% by volume, it is di-fficult to achieve smooth transportation of the slurry -from the mixing tank to the granulation apparatus by means of a pump. On the other hand, if the water content of the slurry exceeds 30~ by volume, it is necessary to have more water evaporate in the granulation apparatus, thereby leading to an increased energy demand. Such a high water content is accompanied by another drawback in that the water content of the granular substance to be obtained will be high and a separate drier will be required.
Although fine solid particles are contained in the thus-obtained high temperature slurry, these solid particles have particle sizes within the above range and are uniformly dispersed in the slurry, thereby making it possible to feed the slurry to a spouted bed or fluidized bed granulation apparatus, which will be described below, by means of a pump. Owing to the nature of the slurry, spray nozzles of the granulation apparatus will be protected from clogging. It is pre-ferred to conduct the agitation of the reaction mixture in the mixing tank at a speed of 150 -500 r.p.m. It is generally preferred to maintain the slurry at 80 - 130C in the mixing tank, although it varies depending on the composition and the like of the intended compound fertilizer. The residence time of the slurry in the mixing
4~3 tank is preferably 20 minutes or less, and particularly, 10 minutes or less. A residence time exceeding 20 minutes is not preferred because it tends to induce a quality alteration to the compound fertilizer due to interactions among the raw material fertilizer substances.
The high temperature slurry prepared in the mixing tank is then sprayed into a granulation spacing of a spouted bed or fluidized bed granulation apparatus by a pump through s?ray nozzles and is allowed to stick to priming pa.-ticles floating in the granulation spacing. As such priming particles, may be employed excessively large granules (after pulverization) and excessively small granules, both of which granules are discharged from the granulation apparatus and separated from granules of the desired particle size range by a classifier. Any known spouted bed granulation apparatus or fluidized bed granu-lation apparatus may be employed in the present invention.
The embodiment of this invention will hereinafter be described with reference to the accompanying drawing.
Raw material phosphoric acid, sulfuric acid, nitric acid or a mixture thereof is charged into a tubular reactor 1 through a line 5 or 6. A part of the whole ammonia required to make the molar ratio of ammonia to phosphoric acid 1.4 to 1, is supplied through a line 7 to carry out a reaction.
The reaction mixture from the tubular reactor 1 is introduced into a mixing tank 2 by coupling an outlet nozzle of the tubular reactor l directly to the mixing tank 2. The mixing tank 2 is provided with a high-speed agitator 3 which may be rotated at 150 - 500 r.p.m., whereby completing in a short period of time -the mixing of the reaction mixture with a solid raw material containing agronomically e-ffective components such as N, P and/or K, or an aqueous solution or molten liquid thereof, or a solid diluent -fed into the mixing tank 2 via a line 8 or 9. On the other hand, the remaining part of the whole ammonia which is excessive to the above-mentioned ratio, is supplied into the mixing tank 2 through a line 10, whereby achieving the desired molar ratio. While carrying out these mixing or reaction operations, the water is evaporated from the reaction mixture by virtue of reac~ion heat generated in the tubular reactor 1 and/or mlxing tank 2.
The thus-evaporated water is sent together with a small quantity of ammonia gas via a line 12 to a gas scrubber 11, where it is washed with water, phosphoric acid, sulfuric acid or a mixture thereof supplied through a line 2~. Water, phosphoric acid, sulfuric acid or a mixture thereof which has absorbed ammonia is fed to the tubular reactor l through a line 29. The thus-washed gas is released into the atmosphere.
The above-described solid raw material containing the agronomically effective components includes, for example, urea, ammonium sulfate, ammonium nitrate, ammonium phos-phates, ammonium chloride, potassium phosphates, calcium superphosphate, calcined phosphate fertilizer, potassium sulfate, potassium chloride, potassium metaphosphate, a urea-aldehyde condensate Eertilizer, magnesium silicate, calcium silicate, various trace elements such as Zn, Mn, Mo, Cu, Fe and B, etc. Examples of molten liquids containing agronomically effective components include urea, ammonium nitrate and the like. Examples of raw material solid diluents include gypsum, bentonite, etc. The aqueous solution containing agronomically effective components includes, for example, an aqueous solution containing water-soluble substances out o-f the above-described -fertilizer substances.
A predetermined amount of priming particles is supplied through a line 17 into a spouted bed granulation apparatus 15. An upwardly-directed spouted bed o-f the priming particles is formed within the granulation apparatus 15 by a flow o-f the heated air supplied through a Iine 16.
At the same time, the high temperature slurry is supplied -from the mixing tank 2 through a pump ~ and line 13 to the granulation apparatus 15 and sprayed upwardly through slurry spray nozzles 1~ provided in the spouting bed granulation apparatus 15 at a lower location thereof, thereby causing the thus-sprayed liquid droplets to stick to the -floating priming particles and to become larger while drying the thus-enlarged granules with the air flow.
ll -The water evaporated from the high temperature slurry and the air flow generated in the granulation apparatus 15 and containing fine particles are sent through a line 1~ to a separator 19, where the fine particles are removed, and then released into the atmosphere. The fine particles caugh-t by the separator 19 are conveyed to a storage tank 22, After enlargement in the granulation apparatus 15, the resulting granules (having a wide variety o-f particle sizes -from large to small) are fed through a line 20 to a classifier 21, where they are classified into three groups, i.e., those having diameters within -the desired particle size range and to be finished to a final prodùct, those having particle sizes larger than the upper limit of the desired particle size range and those having par-ticle sizes smaller than the lower limit of the desired particle size range. Excessively large granules are fed to a pulverizer 25 while excessively small particles are tempo-rarily stored in the storage tank 22. The final product is cooled down in a cooler 23 and sent outside the system through a line 24. The excessively large particles are pulverized by the pulverizer 25 and then recycled to the classifier 21 through a line 26. The excessively small particles, which have been temporarily stored in the storage tank 22, are recycled via a line 17 to the granu-lation apparatus 15. In order to control the particle size 24~3 distribution at the outlet o:E the granulation apparatus 15, the amount of excessively small particles to be recycled is controlled by a feeder 27.
According to this invention, a granular compound fertilizer containing at least two components selected :Erom N, P and K can be effectively manufactured from a reaction mixture which has been obtained by reacting phosphoric acid, sulfuric acid, nitric acid or a mixture thereof with ammonia in a tubular reactor. Since a slurry prepared from the above-mentioned reaction mixture is subjected to granulation in a spouted bed or Eluidized bed, it is possible to lower the load of the drying step in the granu-lation process. In addition~ the evaporation of water` from the reaction mixture can be effected in the course of the preparation of the slurry by virtue of the reaction ~eat between ammonia and the acid. Since the reaction mixture is supplied in the slurry form to the granulation step, it is -feasible to add, upon preparation of the slurry, any desired fertilizer substance containing desired agronomically effective components in desired concentrations or a solid diluent to the reaction mixture so as to adjust the compo-sition of the intended final product. Accordingly, the process of this invention can be applied to manu~acture granular compound -fertilizers of any composition. Further-more, the deposition of ammonium monohydrogen phosphate and clogging in the tubular reactor are avoided in the present `
4 ~ 3 process, since ammonia is reacted with phosphoric acid in two steps, that is, in the tubular reactor and the mixing tank.
The invention will be described further in the following examples.
Example 1:
A manufacture test of a granular compound fertilizer containing N and P in amounts of 18% by weight and 46% by weight (in terms of P2O5), respectively, and having diameters in a range of from 1 to 3.5 mm was carried out as follows in accordance with the process illustrated in the accompanying drawing: The test was conducted using a tubular reactor of 50 mm in inner diameter and Z,000 mm in length and a mixing tank with an effective volume of 50 Q and equipped with an agitator rotatable at 200 r.p.m.
I'he spouted- bed granulation apparatus was generally of a cylindrical shape and was formed at a lower part thereof into an inverted truncated conical shape. Its diameter was 1,000 mm at the cylindrical part and its e-ffective volume was 250 Q.
Into the tubular reactor 1, were directly charged 373 kg/hour of liquid ammonia at 0C through the line 7, 800 kg/hour (in terms of P2O5) o~ 5~ wt.% phosphoric acid at 25C via the line 5 and 99 kg/hr of 98 wt.% of sulfuric acid at 25C through the line 6. In addition, the reactor 1 was fed with 2,247 kg/hr ~in terms of P2O5) of 32.4 wt.%
of phosphoric acid at 30C through the line 28. The latter phosphoric acid was first used as an absorbent in the gas scrubber 11 to recover ammonia gas accompanied with steam which had been separated in the mixing tank 2 and then charged into the reactor 1 via the line 29. The reaction mixture was then introduced into the mixing tank 2, where it was reacted with 192 kg/hr of liquid ammonia at 0C
supplied through the line lO, thereby providing 2,985 kg/hr of slurry at 110C which contained 15% by weight of water and 46% by weight of solid components and consisting principally of diammonium hydrogenphosphate and ammonium sulfate. The resultant slurry was transported through the slurry pump 4 and line 13 and sprayed through the spray nozzles 14 disposed in the spouted bed granulation apparatus 15 which were operated under the following operation condi-tions:
Amount of air blown in the 8,300 Nm3/hr granulation apparatus Temperature of air blown into O
the granulation apparatus 170 C
Temperature in the granulation 70 - 75C
apparatus Amount of priming particles 2,710 - 2,760 kg/hr Enlarged granules of a compound fertilizer were obtained at the outlet of the line 20 at a rate of 5,180
The high temperature slurry prepared in the mixing tank is then sprayed into a granulation spacing of a spouted bed or fluidized bed granulation apparatus by a pump through s?ray nozzles and is allowed to stick to priming pa.-ticles floating in the granulation spacing. As such priming particles, may be employed excessively large granules (after pulverization) and excessively small granules, both of which granules are discharged from the granulation apparatus and separated from granules of the desired particle size range by a classifier. Any known spouted bed granulation apparatus or fluidized bed granu-lation apparatus may be employed in the present invention.
The embodiment of this invention will hereinafter be described with reference to the accompanying drawing.
Raw material phosphoric acid, sulfuric acid, nitric acid or a mixture thereof is charged into a tubular reactor 1 through a line 5 or 6. A part of the whole ammonia required to make the molar ratio of ammonia to phosphoric acid 1.4 to 1, is supplied through a line 7 to carry out a reaction.
The reaction mixture from the tubular reactor 1 is introduced into a mixing tank 2 by coupling an outlet nozzle of the tubular reactor l directly to the mixing tank 2. The mixing tank 2 is provided with a high-speed agitator 3 which may be rotated at 150 - 500 r.p.m., whereby completing in a short period of time -the mixing of the reaction mixture with a solid raw material containing agronomically e-ffective components such as N, P and/or K, or an aqueous solution or molten liquid thereof, or a solid diluent -fed into the mixing tank 2 via a line 8 or 9. On the other hand, the remaining part of the whole ammonia which is excessive to the above-mentioned ratio, is supplied into the mixing tank 2 through a line 10, whereby achieving the desired molar ratio. While carrying out these mixing or reaction operations, the water is evaporated from the reaction mixture by virtue of reac~ion heat generated in the tubular reactor 1 and/or mlxing tank 2.
The thus-evaporated water is sent together with a small quantity of ammonia gas via a line 12 to a gas scrubber 11, where it is washed with water, phosphoric acid, sulfuric acid or a mixture thereof supplied through a line 2~. Water, phosphoric acid, sulfuric acid or a mixture thereof which has absorbed ammonia is fed to the tubular reactor l through a line 29. The thus-washed gas is released into the atmosphere.
The above-described solid raw material containing the agronomically effective components includes, for example, urea, ammonium sulfate, ammonium nitrate, ammonium phos-phates, ammonium chloride, potassium phosphates, calcium superphosphate, calcined phosphate fertilizer, potassium sulfate, potassium chloride, potassium metaphosphate, a urea-aldehyde condensate Eertilizer, magnesium silicate, calcium silicate, various trace elements such as Zn, Mn, Mo, Cu, Fe and B, etc. Examples of molten liquids containing agronomically effective components include urea, ammonium nitrate and the like. Examples of raw material solid diluents include gypsum, bentonite, etc. The aqueous solution containing agronomically effective components includes, for example, an aqueous solution containing water-soluble substances out o-f the above-described -fertilizer substances.
A predetermined amount of priming particles is supplied through a line 17 into a spouted bed granulation apparatus 15. An upwardly-directed spouted bed o-f the priming particles is formed within the granulation apparatus 15 by a flow o-f the heated air supplied through a Iine 16.
At the same time, the high temperature slurry is supplied -from the mixing tank 2 through a pump ~ and line 13 to the granulation apparatus 15 and sprayed upwardly through slurry spray nozzles 1~ provided in the spouting bed granulation apparatus 15 at a lower location thereof, thereby causing the thus-sprayed liquid droplets to stick to the -floating priming particles and to become larger while drying the thus-enlarged granules with the air flow.
ll -The water evaporated from the high temperature slurry and the air flow generated in the granulation apparatus 15 and containing fine particles are sent through a line 1~ to a separator 19, where the fine particles are removed, and then released into the atmosphere. The fine particles caugh-t by the separator 19 are conveyed to a storage tank 22, After enlargement in the granulation apparatus 15, the resulting granules (having a wide variety o-f particle sizes -from large to small) are fed through a line 20 to a classifier 21, where they are classified into three groups, i.e., those having diameters within -the desired particle size range and to be finished to a final prodùct, those having particle sizes larger than the upper limit of the desired particle size range and those having par-ticle sizes smaller than the lower limit of the desired particle size range. Excessively large granules are fed to a pulverizer 25 while excessively small particles are tempo-rarily stored in the storage tank 22. The final product is cooled down in a cooler 23 and sent outside the system through a line 24. The excessively large particles are pulverized by the pulverizer 25 and then recycled to the classifier 21 through a line 26. The excessively small particles, which have been temporarily stored in the storage tank 22, are recycled via a line 17 to the granu-lation apparatus 15. In order to control the particle size 24~3 distribution at the outlet o:E the granulation apparatus 15, the amount of excessively small particles to be recycled is controlled by a feeder 27.
According to this invention, a granular compound fertilizer containing at least two components selected :Erom N, P and K can be effectively manufactured from a reaction mixture which has been obtained by reacting phosphoric acid, sulfuric acid, nitric acid or a mixture thereof with ammonia in a tubular reactor. Since a slurry prepared from the above-mentioned reaction mixture is subjected to granulation in a spouted bed or Eluidized bed, it is possible to lower the load of the drying step in the granu-lation process. In addition~ the evaporation of water` from the reaction mixture can be effected in the course of the preparation of the slurry by virtue of the reaction ~eat between ammonia and the acid. Since the reaction mixture is supplied in the slurry form to the granulation step, it is -feasible to add, upon preparation of the slurry, any desired fertilizer substance containing desired agronomically effective components in desired concentrations or a solid diluent to the reaction mixture so as to adjust the compo-sition of the intended final product. Accordingly, the process of this invention can be applied to manu~acture granular compound -fertilizers of any composition. Further-more, the deposition of ammonium monohydrogen phosphate and clogging in the tubular reactor are avoided in the present `
4 ~ 3 process, since ammonia is reacted with phosphoric acid in two steps, that is, in the tubular reactor and the mixing tank.
The invention will be described further in the following examples.
Example 1:
A manufacture test of a granular compound fertilizer containing N and P in amounts of 18% by weight and 46% by weight (in terms of P2O5), respectively, and having diameters in a range of from 1 to 3.5 mm was carried out as follows in accordance with the process illustrated in the accompanying drawing: The test was conducted using a tubular reactor of 50 mm in inner diameter and Z,000 mm in length and a mixing tank with an effective volume of 50 Q and equipped with an agitator rotatable at 200 r.p.m.
I'he spouted- bed granulation apparatus was generally of a cylindrical shape and was formed at a lower part thereof into an inverted truncated conical shape. Its diameter was 1,000 mm at the cylindrical part and its e-ffective volume was 250 Q.
Into the tubular reactor 1, were directly charged 373 kg/hour of liquid ammonia at 0C through the line 7, 800 kg/hour (in terms of P2O5) o~ 5~ wt.% phosphoric acid at 25C via the line 5 and 99 kg/hr of 98 wt.% of sulfuric acid at 25C through the line 6. In addition, the reactor 1 was fed with 2,247 kg/hr ~in terms of P2O5) of 32.4 wt.%
of phosphoric acid at 30C through the line 28. The latter phosphoric acid was first used as an absorbent in the gas scrubber 11 to recover ammonia gas accompanied with steam which had been separated in the mixing tank 2 and then charged into the reactor 1 via the line 29. The reaction mixture was then introduced into the mixing tank 2, where it was reacted with 192 kg/hr of liquid ammonia at 0C
supplied through the line lO, thereby providing 2,985 kg/hr of slurry at 110C which contained 15% by weight of water and 46% by weight of solid components and consisting principally of diammonium hydrogenphosphate and ammonium sulfate. The resultant slurry was transported through the slurry pump 4 and line 13 and sprayed through the spray nozzles 14 disposed in the spouted bed granulation apparatus 15 which were operated under the following operation condi-tions:
Amount of air blown in the 8,300 Nm3/hr granulation apparatus Temperature of air blown into O
the granulation apparatus 170 C
Temperature in the granulation 70 - 75C
apparatus Amount of priming particles 2,710 - 2,760 kg/hr Enlarged granules of a compound fertilizer were obtained at the outlet of the line 20 at a rate of 5,180
5,240 kg/hr. The water content in the enlarged granules was 1.5 - 2~5% by weight.
The thus-granulated compound fertilizer was classified at the classifier 21 into those having diameters within the desired particle size range for the -final product, those having excessively large particle sizes and those having excessively small particle sizes which amounted on average to 48.0%, 5.3% and 46.7%, respectively. Ihe final product was obtained at a rate of 2,460 - 2,510 kg/hr. The granular -final product was cooled in the cooler 23 to 45C, which is a temperature suitable for storage, and discharged out of the system through the line 24.
Example 2:
A manufacture test of a granular compound fertilizer containing N, P and K in amounts of 19% by weight, 19% by weight ~in terms of P2O5) and 19% by weight (in terms of K2O), respectively, and having diameters in a range of from 1 to 4 mm was carried out as follows in accordance with the same process as that employed in Example Into the tubular reactor 1 in the same manner as that followed in Example 1 were supplied 259 kg/hr of liquid ammonia at 0C through the line 7, 1,253 kg/hr (in terms of P2O5) of 54 wt.% of phosphoric acid at Z5C via the line 5, 65 kg/hr of 98 wt.% of sulfuric acid at 25C through -the line 6, and 583 kg/hr ~in terms of P2O5) of 21.7 wt.% of phosphoric acid at 30C via the line 28, The resulting reaction mixture was introduced into the mixing tank 2 and combined with 1,267 kg/hr of potassium chloride having particle sizes of 1,000 ~m or smaller and maintained at room temperature and 1,196 kg/hr of a 96 wt.% aqueous solution of urea supplied at 110C through the line 9, thereby obtaining a slurry having a temperature of 105C
and containing 6% by weight of water and 30.5% by weight of solid components at a rate of 4,161 kg/hr. The thus-obtained slurry was conveyed through the slurry pump 4 and line 3 and sprayed through the spray nozzles 14 of ~he spouted bed granulation apparatus 15 operated under the following operation conditions:
e Amount of air blown into the 8 500 Nm3/hr granulation apparatus Temperature of air blown into 50C
the granulation appaTatus Temperature in the granulation 55 - 60C
apparatus Amount of priming particles 4,030 - ~,270 kg/hr supplied Enlarged granules of a compound -fertilizer were obtained at a rate of 7,865 - 8,345 kg/hr. These granules had a water content of 1 - 1.5% by weight.
I'he thus granulated compound fertilizer was classified at the classifier 21 into those having diameters within the desired particle size range for the Einal product, those having excessively large particle sizes and those having excessively small particle sizes which amounted on average to 49.6%, 1.0% and 49.4%, respectively. The final product was obtained at a rate of 3,840 - 3,920 kg/hr.
The final product was cooled to 45C in the cooler 23 and then discharged out of the system.
\
The thus-granulated compound fertilizer was classified at the classifier 21 into those having diameters within the desired particle size range for the -final product, those having excessively large particle sizes and those having excessively small particle sizes which amounted on average to 48.0%, 5.3% and 46.7%, respectively. Ihe final product was obtained at a rate of 2,460 - 2,510 kg/hr. The granular -final product was cooled in the cooler 23 to 45C, which is a temperature suitable for storage, and discharged out of the system through the line 24.
Example 2:
A manufacture test of a granular compound fertilizer containing N, P and K in amounts of 19% by weight, 19% by weight ~in terms of P2O5) and 19% by weight (in terms of K2O), respectively, and having diameters in a range of from 1 to 4 mm was carried out as follows in accordance with the same process as that employed in Example Into the tubular reactor 1 in the same manner as that followed in Example 1 were supplied 259 kg/hr of liquid ammonia at 0C through the line 7, 1,253 kg/hr (in terms of P2O5) of 54 wt.% of phosphoric acid at Z5C via the line 5, 65 kg/hr of 98 wt.% of sulfuric acid at 25C through -the line 6, and 583 kg/hr ~in terms of P2O5) of 21.7 wt.% of phosphoric acid at 30C via the line 28, The resulting reaction mixture was introduced into the mixing tank 2 and combined with 1,267 kg/hr of potassium chloride having particle sizes of 1,000 ~m or smaller and maintained at room temperature and 1,196 kg/hr of a 96 wt.% aqueous solution of urea supplied at 110C through the line 9, thereby obtaining a slurry having a temperature of 105C
and containing 6% by weight of water and 30.5% by weight of solid components at a rate of 4,161 kg/hr. The thus-obtained slurry was conveyed through the slurry pump 4 and line 3 and sprayed through the spray nozzles 14 of ~he spouted bed granulation apparatus 15 operated under the following operation conditions:
e Amount of air blown into the 8 500 Nm3/hr granulation apparatus Temperature of air blown into 50C
the granulation appaTatus Temperature in the granulation 55 - 60C
apparatus Amount of priming particles 4,030 - ~,270 kg/hr supplied Enlarged granules of a compound -fertilizer were obtained at a rate of 7,865 - 8,345 kg/hr. These granules had a water content of 1 - 1.5% by weight.
I'he thus granulated compound fertilizer was classified at the classifier 21 into those having diameters within the desired particle size range for the Einal product, those having excessively large particle sizes and those having excessively small particle sizes which amounted on average to 49.6%, 1.0% and 49.4%, respectively. The final product was obtained at a rate of 3,840 - 3,920 kg/hr.
The final product was cooled to 45C in the cooler 23 and then discharged out of the system.
\
Claims (9)
1. A process for manufacturing a granular compound fertilizer containing at least two agronomically effective components selected from N, P and K, which comprises reacting phosphoric acid, sulfuric acid or nitric acid or a mixture thereof and ammonia in a tubular reactor to form a solution containing diammonium hydrogenphosphate, ammonium dihydrogenphosphate, ammonium sulfate, ammonium nitrate or a mixture thereof; introducing the solution into a mixing tank and either causing its water to evaporate to obtain a high temperature slurry having a liquid content of 40 - 90% by volume or causing its water to evaporate and, at the same time, mixing a solid fertilizer substance or solid diluent having particle sizes of 50 - 1,000 µm or a molten liquid or aqueous solution of a fertilizer substance with the solution to obtain a high temperature slurry having a liquid content of 40 - 90% by volume; spraying the thus-obtained high temperature slurry into the spacing of a granulation zone of a spouted bed granulation apparatus or fluidized bed granulation apparatus, thereby causing the thus-sprayed slurry to stick to priming particles floating in the spacing and thus forming enlarged granules; and drying and/or cooling the thus-enlarged granules.
2. The process according to Claim 1, wherein the temperature of the slurry ranges from 80°C to 130°C.
3. The process according to Claim 1, wherein the slurry has a liquid content of 40 - 60% by volume.
4. The process according to Claim 1, wherein the fertilizer substance is a compound containing at least one of N, P and K, or a trace element.
5. The process according to Claim 1, wherein the solid diluent is gypsum or bentonite.
6. The process according to Claim 1, wherein the molten liquid o-f the fertilizer substance is molten urea or ammonium nitrate.
7. The process according to Claim 1, wherein the residence time of the slurry in the mixing tank is 20 minutes or less and the slurry is agitated at 150 - 500 r.p.m.
8. The process according to Claim 1, wherein the priming particles have the same composition as the granular compound -fertilizer.
9. The process according to Claim 1, wherein phosphoric acid or a mixture of phosphoric acid and sulfuric acid or nitric acid is reacted with ammonia in the tubular reactor in such a way that the molar ratio of ammonia to phosphoric acid in the resulting ammonium phosphate in a reaction mixture ranges from 1.3 to 1.6 to 1 and the reaction mixture is then reacted in the mixing tank so that the molar ratio o-f ammonia to phosphoric acid in the resultant ammonium phosphate falls within a range of from 1.4 to 2.0 to 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25246/1982 | 1982-02-20 | ||
| JP57025246A JPS58145685A (en) | 1982-02-20 | 1982-02-20 | Manufacture of granular composite fertilizer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1192413A true CA1192413A (en) | 1985-08-27 |
Family
ID=12160625
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000421902A Expired CA1192413A (en) | 1982-02-20 | 1983-02-18 | Process for manufacturing granular compound fertilizers |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS58145685A (en) |
| KR (1) | KR840004050A (en) |
| CA (1) | CA1192413A (en) |
| DE (1) | DE3305851A1 (en) |
| FR (1) | FR2521984A1 (en) |
| GB (1) | GB2116159A (en) |
| IT (1) | IT1163116B (en) |
| NL (1) | NL8300615A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2493290B1 (en) | 2009-10-27 | 2016-08-17 | Basf Se | Preparation of pesticide granulates using a spouted bed apparatus |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GR1003453B (en) * | 1999-07-07 | 2000-10-12 | ���������� ���������� �.�. | Method for the production of granular ammonium sulphate |
| KR100771488B1 (en) * | 2006-01-10 | 2007-10-30 | 주식회사 제철세라믹 | Granular fertilizer for preventing generation of malodor |
| KR100771489B1 (en) * | 2007-01-04 | 2007-10-30 | 주식회사 제철세라믹 | Ggranular residual gymsum fertilizer for preventing generation of malodor and manufacturing method thereof |
| EP2301917A1 (en) | 2009-09-16 | 2011-03-30 | Stamicarbon B.V. | Removal of urea and ammonia from exhaust gases |
| CN104529591A (en) * | 2014-12-17 | 2015-04-22 | 贵州开磷（集团）有限责任公司 | Method and device for preparing bulk blending fertilizer by using nitro nitrogen and phosphorus master batches |
| EP3330241A1 (en) | 2016-12-01 | 2018-06-06 | YARA International ASA | Fertilizer particle |
| EP3461803A1 (en) * | 2017-10-02 | 2019-04-03 | Evonik Degussa GmbH | Method for the production of granules containing dipeptide |
| CN109626395B (en) * | 2019-01-29 | 2023-11-28 | 原初科技（北京）有限公司 | Ammonia gas preparation device and preparation method |
| CN111423272A (en) * | 2020-03-31 | 2020-07-17 | 湖北万丰化工有限公司 | Method for producing fertilizer by slurry method |
-
1982
- 1982-02-20 JP JP57025246A patent/JPS58145685A/en active Pending
-
1983
- 1983-02-18 CA CA000421902A patent/CA1192413A/en not_active Expired
- 1983-02-18 FR FR8302700A patent/FR2521984A1/en not_active Withdrawn
- 1983-02-18 GB GB08304504A patent/GB2116159A/en not_active Withdrawn
- 1983-02-18 IT IT19657/83A patent/IT1163116B/en active
- 1983-02-18 NL NL8300615A patent/NL8300615A/en not_active Application Discontinuation
- 1983-02-19 KR KR1019830000686A patent/KR840004050A/en not_active Application Discontinuation
- 1983-02-19 DE DE3305851A patent/DE3305851A1/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2493290B1 (en) | 2009-10-27 | 2016-08-17 | Basf Se | Preparation of pesticide granulates using a spouted bed apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1163116B (en) | 1987-04-08 |
| DE3305851A1 (en) | 1983-09-01 |
| NL8300615A (en) | 1983-09-16 |
| GB2116159A (en) | 1983-09-21 |
| FR2521984A1 (en) | 1983-08-26 |
| GB8304504D0 (en) | 1983-03-23 |
| KR840004050A (en) | 1984-10-06 |
| JPS58145685A (en) | 1983-08-30 |
| IT8319657A0 (en) | 1983-02-18 |
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