JPS609992B2 - Method for producing nitrogen-potassium fertilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing inorganic fertilizers, and more particularly to a method for producing inorganic fertilizers, and more particularly, nitrogen-free fertilizers, such as those widely applied where chlorine-free or pallast-free fertilizers are required in agriculture. This invention relates to a method for producing potassium fertilizer.

This fertilizer is essential for plants such as tobacco, oil-producing crops, citrus fruits, grapes, potatoes, flax, and other plants that are not sensitive to chloride ions.

By using nitrogen-potassium fertilizers that do not contain chlorine, it is possible to increase crop yields and improve the quality of agricultural products, such as improving the grade of flax, increasing the amount of starch in potato tubers, and increasing the amount of sugar in grapes. obtain. Processes for producing nitrogen-potassium fertilizers are known, for example by reacting calcium nitrate with potassium chloride in an aqueous medium to form potassium nitrate (see US Pat. No. 3,361,522).
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In this method, the resulting solution is cooled to -10 to -2000, and potassium nitrate crystallizes into a solid phase. Concentrate the mother liquor and extract the double salt KN03 from there at 20-25℃.
After precipitating the CaC12.2LO and removing the calcium chloride precipitate, the mother liquor is further recycled. The biggest disadvantage of the method is the chloride contamination of the final product and the steps of crystallization of potassium nitrate by cooling from -10 to -2000, evaporation of the mother liquor, separation of double salts and separation and purification of calcium chloride from 20 to 2500. The complexity of the techniques involved.
The complexity of such techniques results in significant energy consumption. Processes for preparing potassium nitrate by precipitation from solutions containing calcium nitrate and potassium chloride are also known (see US Pat. No. 3,690,819 and British Patent No. 1,313,926).

In this method, after separating calcium nitrate, the mother liquor is treated with lime to obtain calcium oxychloride CaC12.ao.1. The disadvantages of said process are the chloride contamination of the final product and the complexity of the technical operations, including the step of treating the mother liquor with lime to obtain calcium oxychloride.

Calcium oxychloride is useless and should be discarded, but its disposal leads to environmental pollution with toxic substances. A process for preparing potassium nitrate by reacting calcium nitrate with potassium chloride in the presence of monohydric alcohols, polyhydric alcohols or ketones in aqueous soot is also known (French Patent No. 28
No. 0558).

The disadvantage of this process is that it uses organic compounds which require regeneration and which considerably increases the toxicity, fire hazard and explosion risk associated with the process.

A method for preparing potassium nitrate from calcium nitrate and potassium sulfate is also known (German Patent No. 974061).
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In this method, the starting components, namely potassium sulfate and calcium nitrate, are introduced into the mother liquor in such a way that, based on the stoichiometric ratio, it contains about a 5% excess of calcium nitrate. The obtained gypsum suspension is filtered, the gypsum remaining on the furnace material is washed with water, and the mother liquor is cooled to obtain potassium nitrate. Meanwhile, the mother liquor evaporates,
Let it recirculate. A disadvantage of the method is also the complexity of the method, with the need to precisely adjust the amount of calcium nitrate in solution to a level of 5% excess of the theoretical value.

When the amount of nitrate decreases, “syngenite is formed,
Potassium is significantly reduced. On the other hand, increasing the amount of nitrates promotes the contamination of the final product with calcium nitrate and also promotes the deterioration of the physicochemical properties of the fertilizer due to the hygroscopic nature of calcium nitrate. There is also a method for producing a nitrogen-potassium fertilizer comprising, after reacting potassium sulfate and calcium nitrate in an aqueous medium, separating gypsum from the potassium nitrate solution, evaporating the mother liquor, and subsequently recycling the mother liquor. Known (Soviet inventor certificate No. 3825)
(See No. 95). In this method, the reaction step between calcium nitrate and potassium sulfate is carried out with an excess amount of potassium sulfate. Potassium sulfate is dissolved in the recycled mother liquor, 8-15%
The concentration is K2S04. The major drawback of the method is that it produces fertilizers with an unbalanced ratio of active ingredients, ie nitrogen:potassium ratio, which further reduces the agrochemical effectiveness of the target product.

According to known methods, potassium nitrate as a nitrogen-potassium fertilizer is prepared at a nitrogen:potassium oxide (K20) ratio of 1:3.
．． 4 (approximately 14% nitrogen and approximately 47% K20). However, practical experience has shown that fertilizers for major crops must be rich in nitrogen. Fixed nitrogen, for example in the form of ammonium nitrate, should be used together with potassium nitrate; this fact means that ammonium nitrate must be produced and equipment for powder mixing must be used. Another drawback of the known method is that due to the stratification of the components, heterogeneous fertilizers tend to be produced.

Another drawback of the known method lies in the application of potassium sulfate, which is considered to be in excess of the stoichiometric amount.

If this condition is not met when producing potassium nitrate by known methods, potassium is significantly reduced due to the formation of syngenite K2Ca(S04)2.day20 together with calcium sulfate. It is therefore essential to limit the amount of potassium sulfate precisely to an excess level, which is quite difficult under industrial conditions. The main object of the present invention is to prepare a good nitrogen-rich and chloride ion-free target product by changing the raw materials and methods, and to
The aim is to simplify the technique by eliminating by-products (syngenite).

The main object is to use the method of the present invention, namely to react potassium hydrogen sulfate as a potassium source with calcium nitrate, strontium nitrate or barium nitrate in an aqueous soot, and to treat the resulting reaction product with ammonia, thereby reducing the This is achieved by a method for producing a nitrogen-potassium fertilizer comprising means for separating the poorly soluble sulfate and isolating the desired product.

To increase the proportion of nitrogen in the nitrogen-potassium fertilizer, the reaction product is treated with ammonia to adjust the pH to 5-7.

Ammonium nitrate is obtained by neutralizing the nitric acid resulting from the reaction of potassium hydrogen sulfate and nitrate. The N:K20 ratio in nitrogen-potassium fertilizers is defined as the ratio of ammonium nitrate to potassium nitrate in the solution. In order to improve the filtration properties of poorly soluble salts, such as barium sulfate, ammonia is continuously added to the reaction product.

That is, the ammonia treatment is carried out until the pH becomes -5 to separate the hardly soluble salts, and then the reaction product is further neutralized with ammonia to a pH of 5-7. In order to increase the solubility of the starting compound and of the potassium or ammonium nitrate produced, it is suitable to carry out the process for a period of from 60 to 100 hours.

However, the process may be carried out at even higher temperatures, with additional operational constraints, and at temperatures up to 0.000 C, although with reduced salt solubility and increased energy consumption for solution dehydration. If it is necessary to adjust the fine crystalline precipitate, the temperature may be lowered. The method of the present invention is carried out as follows.

The starting materials are charged to the reactor. Potassium hydrogen sulfate and calcium nitrate, strontium nitrate or barium nitrate are used as starting materials. In the method of the present invention, a fertilizer having any specified ratio N:K20 can be obtained by changing the composition of potassium hydrogen sulfate as necessary. Potassium hydrogen sulfate is prepared by mixing a sulfuric acid solution and potassium sulfate at a predetermined ratio (K2S04:2S04). For this reason, the equivalence ratio is KN0
A nitrogen-potassium fertilizer containing 3 and HN03 is produced;
N:K20 is the specified ratio. It is also possible to use potassium hydrogen sulfate prepared from potassium chloride and sulfuric acid,
In this case, by varying the ratio of KCI to day 2S04, the KCI to day 2S04 in potassium hydrogen sulfate
The specified ratio of 2S04 is maintained. Potassium hydrogen sulfate is produced in one step at low temperatures (80-240°C), whereas known methods for preparing potassium sulfate from potassium chloride and sulfuric acid result in the process being carried out at 500-700°C. The use of potassium hydrogen sulfate prepared from sulfuric acid and potassium chloride in accordance with the present invention requires the use of potassium hydrogen sulfate prepared from sulfuric acid and potassium chloride because of increased metal corrosion, adhesion of reaction products to the reactor walls and contamination of the resulting hydrogen chloride with impurities. It was found to be more effective than the use of potassium sulfate prepared from According to the method of the invention, it is also possible to use acid solutions of potassium sulfate containing nitric acid, such as those resulting from the decomposition of neferite and alunite with nitric acid.

For example, by charging the reaction product into a reactor and
By reacting at 0 to 100 qo, it is possible to increase the solubility of the starting materials and the produced nitrate, and to shorten the reaction time. As I worshiped the hawk, the reaction progressed,
Forms poorly soluble sulfate.

This reaction is shown by the chemical reaction formula below. In the above reaction formula, Me is Ca, Sr, or a mother.

The reaction product obtained in this way is subjected to PH in a reactor.
When treated with ammonia or aqueous ammonia until it reaches 5-7, and the resulting nitric acid is further neutralized, ammonium nitrate is formed by the following reaction.

The obtained suspension was heated in a furnace to dissolve elutriated sulfate (CaS0412L0"CaS04・0,9H20
, mother S04 "SrS04)" and mother liquor are obtained.

This mother liquor is dehydrated by drying or evaporation and used as a homogeneous composite nitrogen-potassium fertilizer.
A final organism consisting of 03 is obtained. In this case, by changing the x:y ratio of potassium hydrogen sulfate, KN03:NH4
N03 ratio changes. In order to change the physicochemical properties of the sparingly soluble sulfate, for example, ammonia is added continuously to the reactive composition in order to prepare a barium sulfate precipitate that is convenient for filtration.

That is, the reaction product was treated with ammonia to give a pH of -5.
After adjusting to
and the final product is isolated, for example by crystallization and drying. The wash liquor obtained when washing off the nada soluble sulfate from the target product can be removed together with the mother liquor or used to wash the newly formed nada soluble sulfate during the preparation of the reaction product, and can also be used for other purposes. used in a strategic manner. For example, the Nada precipitate can be used in the production of building materials.

The nitrogen-potassium fertilizers of the present invention, consisting of potassium nitrate and ammonium nitrate, are promising because the method of the present invention allows the ratio of active ingredients in the compound fertilizer to be varied over a wide range depending on the agricultural requirements. This is because it can be used for many agricultural plants.

The method of the present invention is characterized by a simple technique and is considerably superior to known methods in the following respects: The method of the present invention consists of potassium nitrate and ammonium nitrate, and contains fertilizing ingredients in a specified ratio (N:K20). and enables the preparation of a nitrogen-rich, non-blasting nitrogen-potassium fertilizer containing:
- Due to the crystallization of sparingly soluble sulfates in acidic solvents, there is no risk of potassium loss due to syngenite formation, much simpler process control and lower equipment load:
- The fertilizer obtained by the method of the invention has high agrochemical properties and maintains its homogeneity during transportation and storage:
- The use of potassium hydrogen sulfate in the production of nitrogen-potassium fertilizers reveals the disadvantages inherent in the method of preparing potassium nitrate from potassium sulfate obtained from the reaction of sulfuric acid with potassium chloride (low rationality, lack of equipment at high temperatures). Corrosion, etc.) are eliminated: - The method of the invention makes it possible to utilize potassium sulfate-containing waste, and its use does not generate secondary waste containing harmful substances that pollute the environment: and - The use of barium nitrate or strontium nitrate according to the invention allows the application of production wastes containing these salts.

In order to further understand the present invention, it will be explained in the following examples.

Example 1 Potassium hydrogen sulfate 10k9 (K2S048.5k9 and day 2S041.5
(prepared by mixing with K9) was treated with 10.8 kg of calcium nitrate.

The resulting suspension was neutralized to pH 6.8 with 10% aqueous ammonia and filtered, and the resulting precipitate was washed with wet gypsum (62.25% CaS04.2LO) 17.4k9 and washed. I got the liquid. The mother liquor was dried at 140 qo in a spray dryer to give the final product 12.5k9 with the following composition: KN03-78.80% (potassium content 30.4
8%, total K20 content 36.71%, nitrogen content 10.92
%): N ratio N03-19.60% (nitrogen content 6.86%
); CaS04・2 days 20-1.6%K20-36.7
1%, N-17.78% Therefore, the N:K20 ratio is 1:2
．． It was 1.

Example 2 Potassium chloride (KCI-98%, NaCI-2%) 42.7 in reactor at 100oo for 4 hours
3k9 was treated with concentrated sulfuric acid (93% 2S04) to obtain potassium hydrogen sulfate (98.04% KHS04, 1.64% N
aHS04)76.50k9 was obtained.

In the next step of this process (see Example 1), the washing liquid obtained by washing the plaster [KNH4(N03)2-10.83%,
NaN03-0.10%, NaCI-0.03%, Ca
S04/Phantom LO-0.40%, Day 20-88.64%]
After dissolving this potassium hydrogen sulfate in 136.93k9, add calcium nitrate (17%) for 15 minutes at 60:00.
Processed with 92.16k9.

After diluting the resulting suspension with 55.4 kg of water, the pH was adjusted to 6.5 using 9.48 k9 of ammonia gas.

This suspension (370.49k9) was filtered and the resulting gypsum precipitate was washed with water. As a result, gypsum [CaS04, day 20]
-44.04%, KN ratio (N03) 2-0.7%, Na
NQ-0.01%, ratio ○-54.38%] 214.46
Mixed liquid consisting of k9, mother liquor and concentrated washing liquid [KNH4 (N0
3) 2-29.54%, NaN03-0-26%, Na
CI-0-07%, CaS〇4.2 also 〇10.56%,
20-69.57%] 334.8k9, and 136.93k9 of a dilute wash that was recycled and used for the dilute wash used to dissolve potassium hydrogen sulfate. The mixed solution was dried at 100 qo to obtain the desired product 10 having the following composition.
Got 2k9. KNH4(N03)2-96.95% CaS0412day20-1.83% NaN03-0.86% NaCI-0.22% day20-0.14% The N:K20 ratio of the final product is 1:1. there were.

Example 3 Ammonia water (2
The same operation as in Example 2 was carried out using 47.4k9 of 0% NH3) to obtain a product with the same composition.

Example 4 100 kg of a solution containing 10k9 of potassium hydrogen sulfate (K2S041.0k9 and Hiroshi S049.0k9) was added to 90Q
Treated with calcium nitrate 16k9 at O.

The resulting suspension was neutralized to pH 6.0 using ammonia, separated in a furnace, and the precipitate was washed with water and added to wet gypsum (5.
3.38% CaS04・Group 20) 31k9 was obtained. The mother liquor is evaporated and then dehydrated to produce a final product with the following composition 16.
I got 15k9.

KN03-7.18% N is N03-90.00% CaS0412 days 20-1.49% day 20-1.33% The K20:N ratio in this product was 139.7.

Example 5 Potassium hydrogen sulfate (K2S045k9 and 2S045k9) 10X for 90 minutes at 100 qC
100 kg of a solution containing 9 was treated with barium nitrate 10.8k9.

The resulting suspension was neutralized to pH 3.0 with aqueous ammonia and then filtered. The precipitate remaining on the furnace material was washed with water to obtain 30 kg of wet barium sulfate (62% base S04). The mother liquor was once again neutralized with aqueous ammonia to pH 6.8 and then dried to obtain the final product 14k9 with the following chemical composition. KN03-41.43% N03-58.28% Ratio -0.29% The N:K20 ratio in the final product was 1:1.2.

Example 6 The procedure of Example 5 was repeated.

However, potassium hydrogen sulfate is used for 2 hours at 5°C for 10
% barium nitrate solution 97.2k9. The N:K20 ratio in the final product was 1:1.2, and the composition of the product was also similar to Example 5.

Example 7 Potassium hydrogen sulfate 20k9 between 4 powders in 80x0
A solution containing 100k9 (K2S0410k9 and 2S0410k9) was treated with strontium nitrate 38.8k9.

The resulting suspension was neutralized with ammonia to pH 6.5, filtered, and treated with strontium sulfate (49.6% SrS04).
) Got 59k9. Further, this mother liquor was dried to obtain a final product 28.5k9 having the following composition. KN03-4
0.7% N ratio N03-57.3% SrS04-0.1% Ratio -1.9% The N:K20 ratio in the final product was 1:1.2.

Example 8 Potassium hydrogen sulfate 30k9 (K2S04
20k9 and HN0810k9, or K2S046.
2k9, day 2S047.8kg and KN0316.0k
Solution 100k9 containing 9) was treated with calcium nitrate 19k9 at 70oo for 45 minutes.

The resulting suspension was neutralized with ammonia to pH 6.9, heated in a furnace, and mixed with wet gypsum (56.3% CaS04.2LO
) Got 32k9. Further, this mother liquor was dehydrated to obtain a final product having the following composition. KN03 - 62.70% N day N03 - 34.32% CaS04 12 day 20 - 2.16% day 20 - 0.82% The N:K20 ratio in the final product was 1:1.4.

Claims (1)

[Claims] 1. Potassium hydrogen sulfate in an aqueous medium with calcium nitrate,
The reaction product is reacted with a nitrate selected from the group consisting of barium nitrate and strontium nitrate, the resulting reaction product is treated with ammonia, the hardly soluble sulfate formed during the ammonia treatment is separated, and the desired product is further removed from the mother liquor. A method for producing a nitrogen-potassium fertilizer comprising means for isolating. 2. The method for producing a nitrogen-potassium fertilizer according to claim 1, wherein the reaction product is treated with ammonia to adjust the pH to 5-7. 3. Claim 1, wherein the reaction product is treated with ammonia to adjust the pH to 1-5 and the hardly soluble sulfate is separated, and then the reaction product is subsequently treated with ammonia to adjust the pH to 5-7. A method for producing a nitrogen-potassium fertilizer.