JPH0235713B2 - SHUKUGORINSANENGANJUHIRYONOSEIZOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a condensed phosphate-containing fertilizer. In this specification, all percentages are by weight.
It is.

Condensed phosphates have unique properties compared to orthophosphates. That is, it has properties such as sequestration of metal ions, buffering, and peptizing and dispersing effects, and is used in various industrial fields such as detergents, water treatment agents, metal surface treatment agents, and food processing. On the other hand, regarding fertilizer,
Condensed phosphates have high concentrations of active ingredients in fertilizers due to the condensation of orthophosphoric acid, which saves labor in storage, transportation, fertilization, etc., and also reduces the amount of iron in the soil compared to orthophosphoric acids. It has less fixation of phosphoric acid by aluminum, lime, etc., and has good phosphoric acid movement and dispersion in the soil, and is also slow-release, so it is attracting attention as a fertilizer with high phosphoric acid utilization efficiency. .

Methods for producing condensed phosphates include a method by direct reaction of phosphorus pentoxide and ammonia, and a method by calcination heating of orthophosphate. The former requires high temperature and pressure, and the manufacturing process is complicated. The latter is
It requires a firing temperature of over 200°C, and the product is difficult to handle in a molten state. There is also a method of producing a condensed phosphate by heating a mixture of orthophosphate and urea; however, although this method produces a slightly lower temperature than the first two methods, it requires a long time for heating. Recently, a method for producing ammonium phosphorus has been developed in which a phosphoric acid solution and ammonia are introduced into a pipe reactor and reacted instantly. In this method, the reaction temperature is
When the temperature is raised to 200℃ or higher and about 300℃, condensed ammonium phosphate is generated. To do this method,
The raw material phosphoric acid solution requires a high concentration, and the raw material phosphoric acid solution and ammonia need to be preheated to around 100°C before being supplied.

The present invention eliminates all the drawbacks of the various production methods described above and provides a method for effectively producing condensed phosphate-containing fertilizers at a low temperature of 200°C or less.

The method for producing a condensed phosphate-containing fertilizer according to the present invention is characterized in that a phosphoric acid solution containing urea and ammonia are reacted at a temperature of 200° C. or less in a pipe reactor to produce condensed ammonium phosphate.

As shown in the drawing, the pipe reactor consists of a tubular reactor body 1 with both ends closed, an ammonia supply pipe 2 disposed at one end of the reactor body, and a phosphoric acid solution disposed on both sides of the same end. It consists of a supply pipe 3, a sulfuric acid supply pipe 4, and a product discharge port 5 provided on the other end side of the main body 1.

In this pipe reactor, ammonia and phosphoric acid solutions are supplied from supply pipes 2 and 3 at a gauge pressure of 0.5
Supplied at ~6Kg/ ^cm2 . Therefore, the mixing and reaction of raw materials in the vessel is instantaneous. As the phosphoric acid solution, a wet phosphoric acid solution containing 27 to 55% P ₂ O ₅ is often used. Further, reaction products, generated steam, and volatile matter are discharged from the discharge port 5. The reaction product discharged is in the form of a slurry or mist that is easy to handle. Some of the volatile matter and vapors are recovered in a recovery system.

The temperature at which condensed phosphates are formed is generally 200℃ or higher.
Although it is said that the temperature is about 300°C, in the method of the present invention, condensed ammonium phosphate is sufficiently produced at a temperature of 200°C or lower, especially about 120 to 200°C, due to the effect of urea contained in the phosphoric acid solution. The amount of urea added to the phosphoric acid solution is in the range of 0.1 to 2 moles per mole of P ₂ O ₅ contained, and approximately 0.2 to 1 mole is most effective. When the amount of urea added is less than 0.1 mole, the production rate of condensed phosphoric acid is poor, and when it is more than 2 moles, unreacted urea remains.

The second aspect of the present invention is to prepare a phosphoric acid solution containing urea, ammonia and sulfuric acid in a pipe reactor at a temperature of 200°C.
It is characterized by producing condensed ammonium phosphate through the following reaction.

If the concentration of the phosphoric acid solution is low and the reaction temperature does not reach the predetermined temperature, the necessary reaction temperature can be maintained by adding sulfuric acid. Sulfuric acid is added to the raw phosphoric acid solution or directly introduced into the pipe reactor. As described above, since the reaction temperature is 200°C or less and sulfuric acid is present, the production of biuret is relatively small at 0.3% or less.

Powdered or granular ammonium phosphate containing condensed ammonium phosphate is obtained by spraying the product from the pipe reactor according to this method from a high place such as a spray tower. Furthermore, by spraying the product from the pipe reactor according to this method into a rotating body such as an ammonification granulator or a brunzier, and mixing and granulating it with the returned product, monoammonium phosphate containing condensed ammonium phosphate or can produce granules of diammonium phosphate. Furthermore, the product from the pipe reactor according to the present method is sprayed into a rotating body similar to the above, and mixed and granulated with the returned product and other fertilizer raw materials such as potassium salt, magnesia salt, etc. in the rotating body. ,
A nitrogen, phosphoric acid, potassium and magnesium based granular fertilizer containing condensed phosphates is obtained. These products contain little moisture and require almost no drying because the reaction in the pipe reactor is effective and the rate of moisture evaporation is high. In the case of granules, the product is cooled and sieved to product size using a sieve, and the pulverized products of the sieve and sieve products are returned to the rotating body for granulation.

The condensed phosphate produced by this method is a polyphosphate mainly composed of ammonium pyrophosphate and containing ammonium tripolyphosphate depending on the conditions, although it varies depending on the reaction conditions. When potassium salts and magnesia salts are present, some of these condensed phosphates are also present.

The method of the present invention is configured as described above, and a phosphoric acid solution containing urea and ammonium are reacted instantaneously and efficiently in a pipe reactor. It is simple and effective compared to other methods, and there is less drying burden, etc., and it is possible to economically produce a fertilizer containing condensed phosphate. That is, this method does not require complicated processes at high temperatures, such as the direct method using phosphorus pentoxide and ammonia, or the method of calcining phosphate, and does not require the production of phosphate, unlike the method of calcining a mixture of phosphate and urea. After that, there is no need to mix this with urea and heat it for a long time, and furthermore, in order to generate condensed ammonium phosphate, unlike other methods that use a pipe reactor, the heating temperature is 200℃ or higher.
There is no need for a high temperature reaction of about 300°C, and therefore there is no need to preheat the raw material phosphoric acid solution, ammonia, etc. to about 100°C.

Further, according to the second invention, since sulfuric acid is further added to the phosphoric acid solution containing urea and ammonia, the necessary reaction temperature can be maintained and the formation of biuret can be suppressed.

Example 1 371 parts of a mixed solution obtained by adding 16 parts of urea (N46%) and 18 parts of recovered water to 337 parts of wet phosphoric acid solution (P ₂ O ₅ 55.0%, H ₂ SO ₄ 4.3%), and 48 parts of ammonia, 1/2 inch diameter,
A pipe reactor with a length of 900 mm was fed for 1 hour each at a cage pressure of 4 kg/cm ² . The reaction temperature reached 185°C. The resulting slurry of the reaction product was sprayed into a spray tower with a height of 10 m and allowed to fall. In this way, 354 parts of fertilizer containing powdered or granular condensed ammonium phosphate was obtained. The analysis value of the product is 4.2% moisture.
N was 12.7%, P ₂ O ₅ was 52.3%, and the condensation rate of phosphoric acid was 28%.

Example 2 489 parts of a mixed solution of 438 parts of wet phosphoric acid solution (P ₂ O ₅ 43.0%, H ₂ SO ₄ 2.8%), 33 parts of urea (N46%) and 18 parts of 95% sulfuric acid, and 47 parts of ammonia were used. The pipe reactor was fed as in Example 1. Reaction temperature is 150℃
reached. The resulting slurry of the reaction product was introduced into an ammonification granulator and sprayed onto the returned product, and 33 parts of ammonia was further fed into the granulator to carry out ammonification and granulation. In this way, 400 parts of granular fertilizer containing condensed ammonium phosphate was obtained. The analytical values of the product were 1.2% moisture, 18.6% N, 46.8% P ₂ O ₅ , and 33% phosphoric acid condensation rate.

Example 3 476 parts of a mixed solution of 394 parts of wet phosphoric acid solution (P ₂ O ₅ 27.5%, H ₂ SO ₄ 2.1%) and 82 parts of urea (N46%), 35 parts of ammonia and 120 parts of 95% sulfuric acid were used. The pipe reactor was fed as in Example 1. The reaction temperature is
The temperature reached 120℃. The resulting reaction product was introduced into a rotary granulator, sprayed onto a mixture of 110 parts of potassium chloride (K ₂ O 60%) and the reconstituted product, and dried and cooled. Thus granular fertilizer containing condensed phosphates
Got 500 copies. Product analysis values are moisture 0.9%, N12.9
%, _P2O5 21.8% _{, K2O12.8} %, phosphoric acid condensation rate 47%
It was hot.

Example 4 312 parts of a mixed solution of 195 parts of wet phosphoric acid solution (P ₂ O ₅ 50.0%, H ₂ SO ₄ 4.7%), 41 parts of urea (N46%) and 76 parts of recovered water, and 97 parts of 95% sulfuric acid and 40 parts of ammonia were supplied to the pipe reactor in the same manner as in Example 1.
The reaction temperature reached 195°C. The obtained reaction product was introduced into a rotary granulator to convert potassium chloride ( _K2O60 %)
It was granulated by spraying onto a mixture of 115 parts of sodium hydroxide, 35 parts of magnesium hydroxide (MgO 60%), and the reconstituted product. In this way, 460 parts of granular fertilizer containing condensed phosphate was obtained. Product analysis values are moisture 2.0%, N 10.7%, P ₂ O ₅ 20.6%, K ₂ O 14.6
%, MgO4.3%, and phosphoric acid condensation rate 58%.

[Brief explanation of drawings]

The drawing is a partially cutaway front view of the pipe reactor.

Claims (1)

[Claims] 1. A method for producing a condensed phosphate-containing fertilizer, which comprises reacting a phosphoric acid solution containing urea with ammonia at a temperature of 200° C. or lower in a pipe reactor to produce condensed ammonium phosphate. 2. The method according to claim 1, wherein the reaction temperature is 120 to 200°C. 3. The method according to claim 1 or 2, wherein the phosphoric acid solution contains 0.1 _to 2 moles of urea per 1 mole of _P2O5 . 4. Any one of claims 1 to 3 in which fertilizer elements such as potassium and magnesia are added to the reaction product.
The method described in section. 5. A method for producing a condensed phosphate-containing fertilizer, which comprises reacting a phosphoric acid solution containing urea, ammonia, and sulfuric acid in a pipe reactor at a temperature of 200°C or less to produce ammonium condensed phosphate.