CN1180047A

CN1180047A - Preparation method of lemery salt and ternary compound fertilizer containing nitrogen, phosphorus and potassium

Info

Publication number: CN1180047A
Application number: CN 97105278
Authority: CN
Inventors: 樊彩梅; 李安民; 李双志
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-25
Filing date: 1997-07-25
Publication date: 1998-04-29

Abstract

The present invention relates to a method for producing potassium sulfate without chlorine and potassium and chlorine-contained N, P, K three-component composite fertilizer and by-product hydrochloric acid solution by using potassium chloride and sulfuric acid as raw material and adopting chlorization-conversion process. Said invented method is simple and reasonable in technological process, flexible in operation and strong in practicality, and its reaction speed is rapid, reaction temp. is low, energy consumption is less and cost is low.

Description

Potassium sulfate and nitrogen, phosphorus and potassium three-element compound fertilizer and its production method

The present invention relates to a method for preparing potassium sulfate and ternary composite fertilizer of nitrogen, phosphorus and potassium.

At present, there are three potassium sulfate production processes. One is the direct process, also known as the Mannheim (Nannbeia) process. The sulfuric acid and the potassium chloride react in a high-temperature furnace (500-700 ℃) to obtain potassium sulfate, and the method has the advantages of high temperature, large energy consumption, serious corrosion, large operation technical difficulty and high product purity; the other method is a double decomposition conversion method, namely, potassium chloride and sulfate carry out double decomposition reaction to obtain potassium sulfate, the method is simple, the corrosion of the process is small, the mother liquor amount is large, and the product purity is low; the third is solvent extraction, which has high product purity, low reaction temperature, complicated operation and high production cost. CN1078226A also discloses a method for producing potassium sulfate type ternary compound fertilizer, and CN10600084A discloses a method for producing potassium dihydrogen phosphate and potassium sulfate. But at high cost.

The invention aims to provide an economical, practical and flexible method for preparing potassium sulfate and a nitrogen-phosphorus-potassium ternary compound fertilizer, wherein the raw materials are sulfuric acid, ammonia and potassium chloride.

The purpose of the invention is realized as follows: firstly, NH is prepared₄A circulating solution of CL + KCL; preparing concentrated sulfuric acid into a sulfuric acid solution by using the circulating solution, mixing sulfuric acid and potassium chloride in a reactor for reaction to obtain potassium bisulfate solid, and absorbing hydrogen chloride gas by using water to prepare industrial hydrochloric acid; secondly, performing ammoniation reaction on the potassium hydrogen sulfate solution to generate potassium sulfate and ammonium sulfate, controlling the concentration of free ammonia in the solution, adding a potassium chloride fertilizer, performing double decomposition reaction on the potassium chloride and the ammonium sulfate in an ammonia medium, further converting the ammonium sulfate into the potassium sulfate, and separating to obtain the chlorine-free potassium fertilizer potassium sulfate; and concentrating, cooling and separating the separated mother liquor to obtain the potassium hydrogen compound fertilizer mainly containing ammonium chloride, and then adding corresponding phosphorus and trace element fertilizers to obtain the compound fertilizer.

The detailed steps of the invention are illustrated as follows:

1. circulating solution required by preparation process

Heating and dissolving tap water, fertilizer ammonium chloride and potassium chloride according to the following weight ratio to obtain a circulating solution:

1000 parts of water + NH₄CL 270-360 parts and KCL 60-100 parts

2. Preparation of potassium hydrogen sulfate

And diluting concentrated sulfuric acid with the circulating solution to prepare a solution with the sulfuric acid concentration of 50-85%. H₂SO₄The molar ratio of KCL to KCL is 0.9-1.4: 1, the reaction temperature is controlled at 80-120 ℃, the continuous reaction is carried out for 0.5-1.5 hr under the condition of stirring, potassium bisulfate solid can be obtained, and hydrogen chloride gas generated by the reaction is absorbed by water to prepare hydrochloric acid.

3. Ammoniation of potassium bisulfate

Preparing saturated solution of potassium bisulfate under stirring, introducing ammonia gas or adding ammonia solution for ammoniation treatment.

The reaction time is 0.5-1.0 hr, and the concentration of free ammonia in the solution after the reaction is finished at the reaction temperature of 20-50 ℃ is 3-10%.

4. Conversion of ammonium sulfate to NH₃

Under thecondition of ammonia medium, sulfuric acid and potassium chloride are quickly converted into potassium sulfate under the (NH) condition₄)₂SO₄∶K₂CL₂The molar ratio is 0.9-1.1: 1, the reaction temperature is 20-80 ℃, the reaction time is 0.5-1.1 hr, wherein the content of ammonium sulfate in the solution is 25-35% (wt)

5. Separation of

After ammoniation conversion, solid-liquid separation is carried out to obtain the first-grade potassium sulfate (containing a small amount of ammonium sulfate) for agriculture according with the specification of ZB621006-89, and the first-grade potassium sulfate or industrial potassium sulfate can be obtained after washing and refining, and the aqueous solution returns to the system for reuse.

6. Preparation of chlorine-containing ternary composite fertilizer

Concentrating the mother liquor after separating potassium sulfate to 33-45% (wt), cooling to room temperature, and separating out nitrogen-potassium compound fertilizer mainly containing ammonium chloride, wherein at the moment, the chlorine-containing N, P, K ternary compound fertilizer and special fertilizer can be obtained by adding phosphorus and trace elements according to the proportioning requirements of different ternary compound fertilizers.

In summary, the invention has the following advantages:

1. can produce potassium sulfate as chlorine-free potassium fertilizer

2. Can produce chlorine-containing W, P, K ternary compound fertilizer

3. High reaction speed, low temperature and low energy consumption

4. Low cost, high economic benefit and only converting step to convert K₂SO₄The profit per ton is increased by 200 yuan.

5. The process operation is flexible, simple and reliable.

The following is further detailed by way of example:

example (b):

1. preparing circulating solution

Mixing fertilizer ammonium chloride (containing NH)₄CL 95%), potassium chloride fertilizer (KCL 95%), and tap water through mixing, heating and dissolving to obtain circulating solution.

87g of ammonium chloride, 25.5g of potassium chloride and 300g of water

2. Production of potassium hydrogen sulfate

130ml of concentrated sulfuric acid (98%) is added to 80g of the circulating solution to obtain a 75% sulfuric acid solution, and then the solution is treated with H₂SO₄Adding 150g of potassium chloride into KCL at a molar ratio of 1.2: 1, reacting at 90g under stirring for 1br to obtain potassium bisulfate containing a small amount of free acid, and absorbing hydrogen chloride gas released in the reaction process into a hydrochloric acid solution by using water.

3. Ammoniation of potassium bisulfate

The remaining circulating solution (332.5g) was mixed with potassium hydrogensulfate with stirring, after which 300g of an aqueous ammonia solution (containing NH) was added₃25%) at room temperature for 1 hour.

4. Conversion of ammonium sulfate

After the ammonification of the potassium bisulfate is completed, the temperature of a reaction system is 40g, 240g of potassium chloride is added, the ammonium sulfate in the solution is converted into potassium sulfate, the stirring reaction is carried out for 1 hour, and the warm potassium sulfate product is obtainedby filtering and separating.

5. Potassium sulfate product treatment

Drying the wet potassium sulfate separated from the step 4 at the temperature of below 60 ℃, and weighing to obtain 409.3g of agricultural first-grade potassium sulfate product. The product quality is K₂SO₄92.5% of CL^-Less than or equal to 1 percent. 4, adding about 200ml of water into the wet potassium sulfate obtained by separation, washing to obtain an agricultural high-grade potassium sulfate, and then adding water into the mixture to wash and refine to obtain an industrial potassium sulfate.

6. Production of compound fertilizer

Concentrating the mother liquid after separating potassium sulfate to 45% (wt), cooling to room temperature, and separating the obtained solid solution NH mainly containing ammonium chloride₄CL and KCL, drying below 60 deg.C to obtain 138.8g ammonium chloride product. The product quality is as follows: containing NH₄cl 91.2% with K₂And 5.4 percent of O. At this time, other nutrient elements can be added according to the requirement to produce chlorine-containing ternary compound fertilizer and special fertilizer. The mother liquor after separating the ammonium chloride is recycled.

Claims

1. A process for preparing potassium sulfate and the ternary compound fertilizer containing N, P and K includes such steps as preparing NH₄A circulating solution of CL + KCL; preparing concentrated sulfuric acid into a sulfuric acid solution by using the circulating solution, mixing sulfuric acid and potassium chloride in a reactor for reaction to obtain potassium bisulfate solid, and absorbing hydrogen chloride gas by using water to prepare industrial hydrochloric acid; secondly, performing ammoniation reaction on the potassium hydrogen sulfate solution to generate potassium sulfate and ammonium sulfate, controlling the concentration of free ammonia in the solution, adding a potassium chloride fertilizer, performing double decomposition reaction on the potassium chloride and the ammonium sulfate in an ammonia medium, further converting the ammonium sulfate into the potassium sulfate, and separating to obtain the chlorine-free potassium fertilizer potassium sulfate; and concentrating, cooling and separating the separated mother liquor to obtain the potassium hydrogen compound fertilizer mainly containing ammonium chloride, and then adding corresponding phosphorus and trace element fertilizers to obtain the compound fertilizer.

2. The method for producing potassium sulfate and a nitrogen, phosphorus and potassium ternary compound fertilizer according to claim 1, characterized in that: containing NH₄The CL + KCL circulating solution is prepared by heating and dissolving the following chemical substances in a weight ratio:

1000 parts of tap water, 270-360 parts of fertilizer ammonium chloride and 60-100 parts of fertilizer potassium chloride.

3. The method for producing potassium sulfate and a nitrogen, phosphorus and potassium ternary compound fertilizer according to claim 1, characterized in that: the preparation of the potassium hydrogen sulfate is to dilute concentrated sulfuric acid by using a circulating solution to prepare a sulfuric acid solution with the concentration of 50-85%, H₂SO₄The molar ratio of KCL to KCL is 0.9-1.4: 1, the reaction temperature is controlled at 80-120 ℃, the continuous reaction is carried out for 0.5-1.5 hr under the condition of stirring, potassium bisulfate solid can be obtained, and hydrogen chloride gas released by the reaction isabsorbed by water to prepare hydrochloric acid.

4. The method for producing potassium sulfate and NPK ternary compound fertilizer according to claim 1, wherein the solid potassium bisulfate obtained in claim 3 is mixed into a saturated solution, and ammoniation treatment is performed on the saturated solution with ammonia water or ammonia gas, wherein the reaction time is 0.5-1.0 hr, the reaction concentration is 20-60 ℃, and the content of free ammonia in the solution after the reaction is finished is 3-10%.

5. The method for producing potassium sulfate, NPK ternary compound fertilizer as claimed in claim 1, wherein the step of converting ammonium sulfate and potassium chloride comprises reacting at 20-80 deg.C for 0.5-1.0 hr (NH)₄)₂SO₄∶K₂CL₂The molar ratio is 0.9-1.1: 1, wherein the content of ammonium sulfate in the solution is 25-35%.

6. The method for producing potassium sulfate and ternary compound fertilizer of nitrogen, phosphorus and potassium as claimed in claim 1, wherein after separating the first-grade potassium sulfate, the mother liquor is concentrated to 33-45% (wt), cooled to room temperature, and solid solution NH mainly comprising ammonium chloride is separated out₄The compound fertilizer of CL and KCL nitrogen and potassium can be prepared into ternary compound fertilizer and special fertilizer containing chlorine, nitrogen, phosphorus and potassium by adding phosphorus and trace elements as required.

7. The method for producing potassium sulfate and NPK ternary compound fertilizer as claimed in claim 1, wherein: the first-grade potassium sulfate for agricultural use is refined by adding water to obtain thetop-grade potassium sulfate, and the aqueous solution is returned to the system for reuse.