CN1218005A - Method for preparation of potassium sulfate - Google Patents
Method for preparation of potassium sulfate Download PDFInfo
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- CN1218005A CN1218005A CN 97120953 CN97120953A CN1218005A CN 1218005 A CN1218005 A CN 1218005A CN 97120953 CN97120953 CN 97120953 CN 97120953 A CN97120953 A CN 97120953A CN 1218005 A CN1218005 A CN 1218005A
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- potassium sulfate
- potassium
- sulfate
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Abstract
A process for preparing potassium sulfate features use of ammonium sulfate and potassium chloride as raw materials and includes such technological steps as proportioning by a certain mole ratio, heating, stirring, cooling, centrifugal separation to obtain potassium sulfate crystals, cooling the mother liquid by heat exchanger and then cold-educing crystallizer to obtain three-element (N, K and S) fertilizer and cyclic utilization of the mother liquid. Its advantages are gentle reaction, simple process, less investment in apparatus, low energy consumption, no waste discharge and no environmental pollution.
Description
The present invention relates to a method for preparing potassium sulfate, particularly to a method for preparing potassium sulfate by a double decomposition cold method.
At present, the method for preparing potassium sulfate at home and abroad mostly adopts a thermal method (Mannheim method) and a double decomposition thermal method. The former is to react sulfuric acid and potassium chloride at high temperature to form potassium sulfate, which has relatively strict technological requirement and has the problems of hydrogen chloride recovery, hydrochloric acid corrosion, pollution, etc. The latter uses ammonium sulfate and potassium chloride as raw materials, the reaction temperature of the method is high, the mother solution of potassium sulfate is crystallized and separated by evaporation and concentration, the requirement on the material of equipment is high, the equipment investment is high, the operation cost is large, the medium temperature is about 90 ℃, and people are easily scalded.
The present invention is to overcome the above-mentioned disadvantages of the prior art and to provide a method for preparing potassium sulfate, which has the advantages of mild reaction, simple process, simple mother solution treatment method, low equipment requirement, low investment, low energy consumption, no waste gas, waste liquid, waste residue, and no environmental pollution.
The object of the invention can be achieved by the following measures: a process for preparing potassium sulfate from ammonium sulfate and potassium chloride includes such steps as adding ammonium sulfate and potassium chloride in reactor at the mol ratio of 1: 1.7-2.16, reaction at 35-55 deg.C for 1.5-2.5 hr, cooling to 25-39 deg.C, and centrifugal separation. The mother liquid of potassium sulfate is cooled to 20-28 ℃ by a heat exchanger, enters a cold separation crystallizer to be cooled to 5-17 ℃, and the ternary fertilizer of nitrogen, potassium and sulfur in the mother liquid of potassium sulfate is separated out by crystallization and is recycled.
The object of the invention is also achieved by the following measures: the optimal molar ratio of the ammonium sulfate to the potassium chloride is 1: 1.9-1.96, the optimal reaction temperature is 43-47 ℃, the optimal reaction time is 1.8-2.2 hours, and the optimal cooling temperature is 30-35 ℃. The mother liquid of potassium sulfate is cooled to the optimum temperature of 23-25 ℃ by a heat exchanger and then enters a cold separation crystallizer to be cooled to the optimum temperature of 10-12 ℃. The potassium sulfate mother liquor (hot mother liquor) is cooled by exchanging heat with the ternary fertilizer mother liquor (cold mother liquor) through a heat exchanger.
Compared with the prior art, the invention has the advantages that ① the reaction efficiency is improved due to the proper molar ratio of the ammonium sulfate to the potassium chloride, the reaction temperature, the reaction time and the cooling temperature, and the maximum yield of the potassium sulfate is obtained ② the comprehensive utilization rate of heat is improved, the energy consumption is reduced, and the requirement on the equipment material is reduced due to the heat exchange process, namely, the cold and heat exchange is carried out between the potassium sulfate mother liquor and the ternary fertilizer mother liquor, ③ the investment is reduced, the operation cost is reduced by half due to the adoption of the method for treating the potassium sulfate mother liquor, no secondary waste is discharged, and no pollution is caused.
Description of the attached drawings, which is a process flow chart of a method for preparing potassium sulfate
The invention is described in detail below with reference to the accompanying drawings:
the mol ratio of ammonium sulfate and potassium chloride is 1: 1.7-2.16, the best mol ratio is 1: 1.9-1.96, firstly adding ammonium sulfate and a small amount of potassium chloride into a reaction kettle to form potassium sulfate crystal nucleus, fully stirring until the ammonium sulfate is dissolved, then slowly adding potassium chloride, stirring uniformly and slowly, keeping the reaction temperature at 35-55 ℃, the best reaction temperature at 43-47 ℃, needing 1.5-2.5 hours in the whole reaction process, the best reaction time is 1.8-2.2 hours, and the potassium sulfate generated by the reaction is attached to the originally formed potassium sulfate crystal nucleus to form crystal slurry. Properly cooling the crystal slurry to 25-39 ℃, optimally 30-35 ℃, then feeding the crystal slurry into a thickener, separating out crystals in a centrifuge, cooling the separated potassium sulfate mother liquor to 20-28 ℃ by a heat exchanger, optimally 23-25 ℃, then feeding the separated potassium sulfate mother liquor into a cold separation crystallizer, cooling to 5-17 ℃, optimally 10-12 ℃, crystallizing and separating out nitrogen, potassium and sulfur ternary fertilizers in the potassium sulfate mother liquor, and recycling the ternary fertilizer mother liquor as a reaction medium of ammonium sulfate and potassium chloride.
The step of cooling the potassium sulfate mother liquor by the heat exchanger is called a heat exchange process, and the effect of the process is to cool the potassium sulfate mother liquor by utilizing the cold energy of the ternary fertilizer mother liquor so as to reduce the load of the cold precipitation of the ternary fertilizer and simultaneously reduce the steam amount required by the temperature rise of the ternary fertilizer mother liquor.
The ternary fertilizer cold separation crystallization process has the effects of cooling the potassium sulfate mother liquor to form supersaturated solution, co-crystallizing and separating out partial potassium sulfate and ammonium chloride, separating out the byproduct of the ternary fertilizer of nitrogen, potassium and sulfur by a centrifugal machine, and simultaneously obtaining the qualified ternary fertilizer mother liquor.
The process of preparing potassium sulfate includes the following reaction equation:
The crystallization is carried out in an external cooling type cold precipitation crystallizer. The liquid cooling circulation is realized by pumping out from the upper part of the cold separation by an axial flow pump, cooling by an external cooler and then entering a cold separation central pipe to run from bottom to top. The refrigeration quantity required by the external cooler is provided by an ammonia press.
Quality index of product and by-product
Nitrogen, potassium and sulfur ternary fertilizer of potassium sulfate
K2O≥40％ K2O≥14％
N≥3.5％ N≥19％
CL-Not more than 4 percent of water-soluble S not less than 5 percent
H2O≤6％ H2O≤6％
Claims (4)
1. A process for preparing potassium sulfate from ammonium sulfate and potassium chloride features that the mol ratio of ammonium sulfate to potassium chloride is 1: 1.7-2.16, the reaction temp. is 35-55 deg.C, the reaction time is 1.5-2.5 hr, then cooling to 25-39 deg.C, centrifugal separation to obtain potassium sulfate crystal, the mother liquid of potassium sulfate is cooled to 20-28 deg.C by heat exchanger, and then cooled to 5-17 deg.C by cold crystallizer, and the ternary fertilizer is crystallized out.
2. The method for producing potassium sulfate as claimed in claim 1, wherein the optimum molar ratio of the ammonium sulfate to the potassium chloride is 1: 1.9-1.96, the optimum reaction temperature is 43-47 ℃, the optimum reaction time is 1.8-2.2 hours, the optimum cooling temperature is 30-35 ℃, the mother solution of potassium sulfate is cooled to the optimum temperature of 23-25 ℃ by a heat exchanger, and then the mother solution of potassium sulfate is cooled to the optimum temperature of 10-12 ℃ by a cold crystallizer.
3. The process for preparing potassium sulfate as claimed in claim 1 or 2, wherein a small amount of potassium chloride is added while adding ammonium sulfate to the reaction vessel, and the potassium chloride is slowly added after most of the ammonium sulfate is dissolved.
4. The process for producing potassium sulfate according to claim 1 or 2, wherein the mother solution of potassium sulfate (hot mother solution) is cooled by exchanging heat with the mother solution of ternary fertilizer (cold mother solution) through a heat exchanger.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97120953 CN1218005A (en) | 1997-11-21 | 1997-11-21 | Method for preparation of potassium sulfate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97120953 CN1218005A (en) | 1997-11-21 | 1997-11-21 | Method for preparation of potassium sulfate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1218005A true CN1218005A (en) | 1999-06-02 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 97120953 Pending CN1218005A (en) | 1997-11-21 | 1997-11-21 | Method for preparation of potassium sulfate |
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| CN (1) | CN1218005A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1084299C (en) * | 1999-12-30 | 2002-05-08 | 孙海峰 | Potassium sulfate producing process of mixing and directly heating potassium chloride and ammonium sulfate |
| CN104261433A (en) * | 2014-09-24 | 2015-01-07 | 湘潭市天志科技有限公司 | Method for producing potassium sulfate from potassium/chlorine-ion-containing solid waste |
| CN106315627A (en) * | 2016-08-12 | 2017-01-11 | 宜昌富升化工有限公司 | Production technology of potassium sulfate |
| CN108083298A (en) * | 2018-01-15 | 2018-05-29 | 东南大学 | It is a kind of to prepare the nanocrystalline method of potassium sulfate |
| IT202000018238A1 (en) * | 2020-07-28 | 2022-01-28 | Edale S R L | PRODUCTION PROCESS OF FERTILIZER BASED ON POTASSIUM SULPHATE |
-
1997
- 1997-11-21 CN CN 97120953 patent/CN1218005A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1084299C (en) * | 1999-12-30 | 2002-05-08 | 孙海峰 | Potassium sulfate producing process of mixing and directly heating potassium chloride and ammonium sulfate |
| CN104261433A (en) * | 2014-09-24 | 2015-01-07 | 湘潭市天志科技有限公司 | Method for producing potassium sulfate from potassium/chlorine-ion-containing solid waste |
| CN104261433B (en) * | 2014-09-24 | 2016-06-29 | 湘潭市天志科技有限公司 | A kind of method that solid waste utilized containing potassium, chloride ion produces potassium sulfate |
| CN106315627A (en) * | 2016-08-12 | 2017-01-11 | 宜昌富升化工有限公司 | Production technology of potassium sulfate |
| CN108083298A (en) * | 2018-01-15 | 2018-05-29 | 东南大学 | It is a kind of to prepare the nanocrystalline method of potassium sulfate |
| IT202000018238A1 (en) * | 2020-07-28 | 2022-01-28 | Edale S R L | PRODUCTION PROCESS OF FERTILIZER BASED ON POTASSIUM SULPHATE |
| WO2022023886A1 (en) * | 2020-07-28 | 2022-02-03 | Edale S.R.L. | Process for the production of potassium sulphate based fertilizers |
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