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CN-122010637-A - Method for producing balanced alkaline high-phosphorus compound fertilizer by ammonia-acid method roller granulation

CN122010637ACN 122010637 ACN122010637 ACN 122010637ACN-122010637-A

Abstract

The application relates to the technical field of fertilizer production, and in particular discloses a method for producing a balanced alkaline high-phosphorus compound fertilizer by ammonia-acid roller granulation. The preparation method comprises the steps of raw material pretreatment and proportioning, ammonium phosphate slurry preparation, roller granulation and granulation, drying and screening, cooling and screening, coating treatment, tail gas treatment and resource recovery, process control and the like. The product of the application can effectively regulate the pH value of the acid soil. In addition, the preparation method of the application obtains the advantages of uniform granularity, high strength, energy saving in the production process, good environmental protection benefit and good product storage stability through the cooperative technologies of material returning classification and partition addition, multi-stage temperature control reaction and waste heat cascade utilization, alkaline compatible coating, tail gas Venturi pretreatment and resource recovery and the like.

Inventors

  • LIU TONG
  • JIAN MIN
  • YANG MINGRONG
  • ZHANG YUEYUE

Assignees

  • 金正大诺泰尔化学有限公司

Dates

Publication Date
20260512
Application Date
20251230

Claims (10)

  1. 1. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation is characterized by comprising the following steps of: S1, raw material pretreatment and batching, namely, metering and conveying raw materials with various formulas to a granulating process; S2, preparing ammonium phosphate slurry, namely metering phosphoric acid and gaseous ammonia, then introducing the metered phosphoric acid and the gaseous ammonia into a tubular reactor for neutralization reaction to generate ammonium phosphate slurry, controlling the slurry to be alkaline, and preheating by utilizing reaction waste heat; S3, roller granulation and granulation, namely adding the raw materials conveyed in the step S1, the alkaline slurry prepared in the step S2 and the returned materials into a roller granulator to enable the materials to be agglomerated into granules; s4, drying and primary screening, namely drying the wet granulated particles, screening the dried materials, returning the screen residues to S1 as return materials, and enabling qualified particles to enter a cooling process; S5, cooling and secondary screening, namely primarily cooling qualified particles by a cooler, further cooling the qualified particles by a plate cooler, secondarily screening the cooled particles to obtain final finished particles, and returning the screen residues to S1 as return materials; s6, coating treatment, namely carrying out anti-caking coating treatment on the final finished product particles by adopting a composite coating agent; s7, tail gas treatment and resource recovery, namely purifying tail gas generated in the granulating, drying and cooling processes to realize resource recovery; s8, packaging and storing finished products, namely automatically weighing, sewing, stacking, metering and packaging the coated finished product particles, and then storing in a warehouse; S9, process control, namely monitoring and adjusting key parameters in the production process in real time, and ensuring the quality of a final finished product.
  2. 2. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation according to claim 1, wherein in the step S1, the formula raw materials comprise ammonium chloride, potassium chloride, ammonium sulfate, potassium sulfate, urea, monoammonium phosphate and auxiliary materials, all the raw materials are respectively added into respective bins and then are metered and conveyed, a particle size grading device is arranged in the material returning system, the returned materials generated in the subsequent step S4 and S5 screening processes are collected in a grading manner and are returned to a granulating process, the materials are graded into coarse returned materials and fine returned materials, the particle size range of the coarse returned materials is 2.5-4.25mm, the particle size of the fine returned materials is less than 1.0mm, in the step S3, the coarse returned materials are added from the feeding end of a rotary drum granulator as nucleation cores, the fine returned materials are added from the middle of the rotary drum granulator as wrapping layers, and the adding mass ratio of the coarse returned materials to the fine returned materials is 1:3-1:5.
  3. 3. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation according to claim 1 is characterized in that in the step S2, phosphoric acid and gaseous ammonia are respectively metered and continuously fed into a tubular reactor for neutralization reaction, the concentration of the phosphoric acid is 70-85wt%, the molar ratio of the ammonia to the phosphoric acid is 1.05:1-1.25:1, the neutralization reaction is carried out at the reaction temperature of 60-120 ℃, and the pH value of the generated ammonium phosphate slurry is controlled to be 7-9.
  4. 4. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation is characterized in that in the step S2, a multistage heat exchange coil is arranged on the outer wall of a tubular reactor, a multistage temperature control structure is adopted, the method comprises a first reaction section, a second reaction section and a third reaction section which are sequentially connected, the control temperature of the first reaction section is 60-80 ℃, the control temperature of the second reaction section is 80-100 ℃, the control temperature of the third reaction section is 100-120 ℃, the multistage heat exchange coil is correspondingly arranged on the outer wall of each reaction section, the multistage heat exchange coil is used for carrying out cascade utilization, waste heat of the first reaction section is used for preheating phosphoric acid raw materials to 40-50 ℃, waste heat of the second reaction section is used for preheating returned materials in the step S1 to 50-60 ℃, and waste heat of the third reaction section is used for preheating combustion air entering a hot blast stove.
  5. 5. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation according to claim 1, wherein in the step S3, the temperature of the materials in the rotary drum granulator is controlled to be 55-75 ℃, the rotating speed of the rotary drum granulator is 10-18rpm, the inclination angle is 1-3 degrees, and the residence time of the materials in the granulator is 5-10min, so that the materials are fully agglomerated into granules.
  6. 6. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation according to claim 1, wherein in the step S4, hot air with the temperature of 100-140 ℃ produced by a hot air furnace is adopted for drying wet particles in parallel, the inlet temperature of the hot air for drying is controlled to be 110-130 ℃, the water content of the dried materials is 1.0-2.5wt%, fine powder with the particle size smaller than 1.0mm and large particles with the particle size larger than 4.25mm are separated in the screening process and returned to the step S1 as return materials, wherein the large particles are subjected to crushing treatment firstly, and qualified particles with the particle size between 1.0-4.25mm enter a cooling process.
  7. 7. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation is characterized in that in the step S5, the cooler adopts normal-temperature air for countercurrent cooling to enable the temperature of materials to be reduced to 35-45 ℃, the flow rate of the cooling air is 1.2-2.0m/S, the cooling time is 8-15min, the final product particles with the particle size of 2.0-4.0mm are obtained through secondary screening, and the screen residues are returned to the step S1 to serve as return materials.
  8. 8. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation according to claim 1, wherein in the step S6, the coating treatment is carried out at 40-55 ℃, the final finished product particles are sprayed by taking a composite coating agent from a coating oil buffer tank, the composite coating agent consists of hydrophobic mineral oil and an alkaline stabilizer, the addition amount of the composite coating agent is 0.5-1.5wt% of the mass of the finished product particles, the mass ratio of the hydrophobic mineral oil to the alkaline stabilizer in the composite coating agent is 8:1-10:1, and the alkaline stabilizer is at least one of hydrogenated castor oil derivatives or magnesium stearate.
  9. 9. The method for producing the balanced alkaline high-phosphorus compound fertilizer by the ammonia-acid method roller granulation is characterized in that in the step S7, the tail gas purification treatment is specifically that dry tail gas and cooling tail gas are pretreated through a venturi tube and then purified through a dust remover, the granulated tail gas is washed and absorbed, washing liquid is partially recycled, dust collected by purifying the dry tail gas is led into a washing system to be mixed with ammonia-containing washing liquid, the washing system comprises a phosphoric acid buffer tank and a washing circulation tank, the pH value of the washing liquid in the washing circulation tank is maintained to be 6.0-7.0, the washing liquid recycled for a raw material batching system accounts for 20-40% of the total washing liquid, and nutrient recovery liquid formed by mixing the dust and the ammonia-containing washing liquid is fed into a tubular reactor in the step S2 according to 2-5% of the feeding flow of phosphoric acid.
  10. 10. The method for producing balanced alkaline high-phosphorus compound fertilizer by using drum granulation according to claim 1, wherein in step S9, key parameters monitored and regulated in real time specifically comprise the feeding proportion of ammonia and phosphoric acid in a tubular reactor, the material temperature in a drum granulator and the temperature of drying hot air, and the corresponding operation parameters are regulated according to the monitoring result, so that the production process runs stably.

Description

Method for producing balanced alkaline high-phosphorus compound fertilizer by ammonia-acid method roller granulation Technical Field The application relates to the technical field of fertilizer production, in particular to a method for producing a balanced alkaline high-phosphorus compound fertilizer by using an ammonia-acid method roller granulation method. Background The compound fertilizer is a key agricultural product for guaranteeing the growth and development of crops in agricultural production, wherein phosphorus contained in the high-phosphorus compound fertilizer is a core nutrient element for root system germination, flowering and fruiting of crops, and has important significance for improving stress resistance and yield of crops. For a long time, in order to meet the nutrient requirements of large-scale planting, the acid compound fertilizer is widely applied due to mature production technology and lower cost, but after long-term continuous application, the problems of soil acidification and hardening are more remarkable, so that nutrients such as available phosphorus and potassium in soil can be fixed, the fertilizer utilization rate is reduced, the root growth environment of crops can be damaged, the problems of root burning, growth vigor weakness and the like are caused, and the quality and the yield of crops are seriously influenced. Therefore, the research and development of the alkaline high-phosphorus compound fertilizer capable of adjusting the pH value of the acid soil becomes an urgent requirement for agricultural production, and the ammonia-process roller granulation process becomes a main process selection for producing the high-phosphorus compound fertilizer by virtue of the characteristics of uniform nutrient distribution, high production efficiency and easiness in large-scale implementation. In the existing ammonia acid method roller granulation process, returned materials generated in the screening process are mostly and directly mixed and recycled, grading treatment is not carried out according to the granularity difference, the nucleation core in the granulator and the coating layer materials cannot be accurately matched, so that the particle forming uniformity is poor, meanwhile, a single-section temperature control design is mostly adopted in the tubular reactor, the neutralization reaction of ammonia and phosphoric acid is difficult to fully carry out, and the fluctuation of pH value of slurry is large. The factors together cause that the pH value of the finally produced compound fertilizer product is difficult to stably control in an alkaline range of 7 to 9, the product performance consistency is poor, the function of adjusting the pH value of the acid soil can not be reliably realized, uncertainty is brought to agricultural production application, and popularization and use of the compound fertilizer in an acid soil planting scene are limited. Disclosure of Invention The application provides a method for preparing a balanced type alkaline high-phosphorus compound fertilizer by using an ammonia-process roller granulation process, which aims to solve the problems that the pH value of the high-phosphorus compound fertilizer produced by the existing ammonia-process roller granulation process is difficult to stabilize in an alkaline range of 7-9 and the pH value of acidic soil cannot be reliably regulated. A method for producing balanced alkaline high-phosphorus compound fertilizer by using a roller granulation method comprises the following steps: S1, raw material pretreatment and batching, namely, metering and conveying raw materials with various formulas to a granulating process; S2, preparing ammonium phosphate slurry, namely metering phosphoric acid and gaseous ammonia, then introducing the metered phosphoric acid and the gaseous ammonia into a tubular reactor for neutralization reaction to generate ammonium phosphate slurry, controlling the slurry to be alkaline, and preheating by utilizing reaction waste heat; S3, roller granulation and granulation, namely adding the raw materials conveyed in the step S1, the alkaline slurry prepared in the step S2 and the returned materials into a roller granulator to enable the materials to be agglomerated into granules; s4, drying and primary screening, namely drying the wet granulated particles, screening the dried materials, returning the screen residues to S1 as return materials, and enabling qualified particles to enter a cooling process; S5, cooling and secondary screening, namely primarily cooling qualified particles by a cooler, further cooling the qualified particles by a plate cooler, secondarily screening the cooled particles to obtain final finished particles, and returning the screen residues to S1 as return materials; s6, coating treatment, namely carrying out anti-caking coating treatment on the final finished product particles by adopting a composite coating agent; s7, tail gas treatment and resource recovery, namely pu