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Method for producing nitric phosphate fertilizer at low temperature under vacuum through concentrated crystallization and calcium removal as well asdevice

A concentrated crystallization, vacuum and low temperature technology, applied in fertilization devices, fertilizer mixtures, agriculture, etc., can solve the problems of increasing refrigerant separation and recovery and circulating treatment devices, inert refrigerant medium consumption, refrigerant circulation energy consumption and other problems, shortening the process, reducing The effect of investment in production equipment and increased operating temperature

Inactive Publication Date: 2012-07-18
WENGFU (GRP) CO LTD
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  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

Although the direct freezing and crystallization method with refrigerant has direct contact heat exchange and small process thermal resistance, the disadvantage of this method is the consumption of inert refrigerant medium and the energy consumption of refrigerant cycle, and it is necessary to increase the separation and recovery of refrigerant and the circulation treatment device

Method used

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  • Method for producing nitric phosphate fertilizer at low temperature under vacuum through concentrated crystallization and calcium removal as well asdevice
  • Method for producing nitric phosphate fertilizer at low temperature under vacuum through concentrated crystallization and calcium removal as well asdevice

Examples

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Effect test

Embodiment

[0021] Embodiment: use 0.6MPa saturated steam to spray refrigeration, evaporate, concentrate and crystallize to remove calcium, and produce nitrogen-phosphorus compound fertilizer with water solubility ≥ 70%.

[0022] Utilize the heat exchanger 1 to heat the mixed solution of the circulating mother liquor and the newly added acidolysis solution to 40°C, and then enter the multi-stage (three-stage) vacuum evaporation, concentration and cooling supersaturation device 2 to produce the supersaturation required for calcium nitrate crystallization, The cooling temperature of the solution and the evaporative concentration process are jointly controlled by the primary steam injector 4, the secondary steam injector 3 and the circulating mother liquor injector 5, forming favorable conditions for calcium nitrate crystal growth, that is, the control of supersaturation. On the one hand, the 0.6MPa pan gas from the power plant, through the adjustment of the injection coefficient of the prima...

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Abstract

The invention discloses a method for producing nitric phosphate fertilizers at a low temperature under vacuum through concentrated crystallization and calcium removal and a device. A vacuum condition is created through adopting steam jet, steam kinetic energy is used to achieve jet refrigeration to evaporate a phosphorite nitric acid hydrolysis solution under low back pressure, and steam is used to absorb heat to achieve the solution refrigeration, so that the separation calcium nitrate from other acid non-soluble substances is achieved in a crystallization fluidized bed. After mother liquor is neutralized and concentrated by gaseous ammonia and a certain amount of potassium is added, the spraying granulation is conducted to obtain a high-concentration ternary compound fertilizer. After calcium nitrate crystals separated through filtration is enabled to be dissolved, and the acid non-soluble substances are removed, the solution absorbs carbon dioxide and gaseous ammonia to produce ammonium nitrate and calcium carbonate to be respectively processed into products. The flow process is shortened, the energy consumption is reduced, the investment of production equipment is reduced, the single-series continuous production of equipment is easy to realize, more importantly, the limitation to the phosphorite impurities is widened, the requirements on the nitric acid concentration are reduced, and the refrigeration temperature is raised.

Description

technical field [0001] The invention belongs to the field of nitrophosphate fertilizer production, in particular to a method and device for low-temperature crystallization and decalcification. Background technique [0002] The production process of nitrophosphate fertilizer has been invented for nearly a hundred years. Throughout the production process of nitrophosphate fertilizer, the differences are mainly reflected in the different crystallization and decalcification methods of phosphate rock acid hydrolysis solution, or the energy saving and consumption reduction of the crystallization process. [0003] The invention relates to a method for producing nitrophosphate fertilizer by using nitric acid to decompose phosphate rock and low-temperature concentration and crystallization to remove calcium. The main reaction of nitric acid to decompose phosphate rock is: [0004] Ca 5 F(H 3 PO 4 ) 3 +10HNO 3 +aq=5Ca(NO 3 ) 2 +3H 3 PO 4 +HF+aq [0005] It can be seen that ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C05G1/00
Inventor 罗容珍颜杰刘兴勇杨虎
Owner WENGFU (GRP) CO LTD
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