Search

CN-122010613-A - Method for producing urea formaldehyde polyglutamic acid compound fertilizer from phosphorus-potassium mixed acid raffinate

CN122010613ACN 122010613 ACN122010613 ACN 122010613ACN-122010613-A

Abstract

The application relates to the technical field of fertilizer production and industrial solid waste resource utilization, and in particular discloses a method for producing urea formaldehyde polyglutamic acid compound fertilizer by using phosphoric-potassium mixed acid raffinate. The preparation method takes phosphorus-potassium mixed acid slurry, polyglutamic acid and urea formaldehyde as main raw materials, and comprises the steps of raw material reaction and mixed acid preparation, multistage neutralization and functional agent mixing, slow-release nitrogen source mixing, returning charge pretreatment and granulation, screening and wrapping, process waste heat recovery and the like. The product of the application can be applied as a special compound fertilizer with the functions of slow release of nutrients and biological stimulation, and has the advantages of balanced nutrients, high utilization rate and soil improvement. In addition, the preparation method of the application realizes the high-value resource utilization of the phosphoric-potassium mixed acid raffinate, and has the advantages of reducing the raw material cost, improving the product performance and saving the production energy consumption through the ammoniation pretreatment of the returned materials and the systematic recovery of the reaction waste heat.

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 preparation method of the urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate is characterized by comprising the following steps of: s1, raw material reaction and mixed acid preparation, namely, after the sulfuric acid reacts with potassium chloride, separating out potassium hydrogen slurry and mixing the potassium hydrogen slurry with phosphoric acid to prepare phosphorus-potassium mixed acid slurry; S2, mixing the neutralization and functional agent, namely carrying out multistage neutralization reaction on the phosphorus-potassium mixed acid slurry, and adding a polyglutamic acid solution in the neutralization process to obtain composite slurry; s3, slowly releasing nitrogen source mixing, namely adding urea formaldehyde into the composite slurry, and mixing to form gunite slurry; S4, returning charge pretreatment and granulation, namely carrying out ammoniation pretreatment on part of the screened fine powder returning charge to obtain pretreated returning charge; s5, screening and packaging, namely drying the wet fertilizer particles, screening, and carrying out spray coating on the combined particles to obtain a compound fertilizer product; s6, recovering the process waste heat, namely recovering and utilizing the chemical reaction heat and/or the absorption heat generated in the manufacturing process.
  2. 2. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 1, wherein in the step S1, the reaction is double decomposition reaction carried out in a conversion reaction tank, the reaction temperature is 80-120 ℃, the mixture after the reaction is subjected to gas-liquid separation, the gas is treated by a hydrochloric acid absorption system to obtain byproduct hydrochloric acid, the liquid is potassium hydroxide slurry, and the effective potassium content in the potassium hydroxide slurry is 15-25% in terms of potassium oxide.
  3. 3. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 1, wherein in the step S2, the multistage neutralization reaction is carried out in a neutralization reaction system, and comprises a first neutralization zone and a second neutralization zone, wherein the pH value of a material is adjusted to 3.5-4.5 in the first neutralization zone, the pH value of the material is adjusted to 5.0-6.5 in the second neutralization zone, and a polyglutamic acid solution is added in the second neutralization zone.
  4. 4. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 3, wherein in the step S2, the material temperature of the second neutralization zone is maintained at 60-85 ℃, the polyglutamic acid solution is added in an amount such that the mass percentage of polyglutamic acid in a final product is 0.2-0.5%, and the polyglutamic acid is gamma-polyglutamic acid with the molecular weight of 100-300kDa.
  5. 5. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 1, wherein in the step S3, the adding amount of urea formaldehyde accounts for 30-60% of the total nitrogen mass of the guniting slurry based on nitrogen element, and the mixing is carried out under the conditions of stirring rotation speed of 30-60r/min and mixing time of 10-30 min.
  6. 6. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 1, wherein in the step S4, the amount of fine powder returned materials in the partial screening accounts for 20-50% of the total returned materials by mass, the ammoniation pretreatment is carried out by utilizing ammonia-containing tail gas or diluted gas ammonia from a neutralization reaction system for contact treatment, the contact time is 60-90S, and the inlet temperature of hot air used for granulation is 180-250 ℃.
  7. 7. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using phosphorus-potassium mixed acid raffinate according to claim 6, wherein the pretreatment returned material formed by ammoniation pretreatment has a surface pH value of 7.5-9.0.
  8. 8. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphoric-potassium mixed acid raffinate according to claim 1, wherein in the step S5, the condition of spraying coating is that the temperature of particles in a coating cylinder is 45-65 ℃ and the relative humidity of air is 25-45%, the coating liquid comprises polyglutamic acid, an anti-caking agent and hydrophilic natural colloid, and the hydrophilic natural colloid is at least one selected from xanthan gum, guar gum and sodium alginate.
  9. 9. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 1, wherein in the step S6, the specific recycling mode is that the recycled heat is used for preheating combustion air required by granulation in the step S4 through a heat exchange device or for pre-concentrating the phosphorus-potassium mixed acid slurry in the step S1.
  10. 10. The method for producing urea formaldehyde polyglutamic acid compound fertilizer by using the phosphorus-potassium mixed acid raffinate according to claim 1 is characterized in that the neutralization reaction system is a first neutralization tank and a second neutralization tank which are arranged in series or is a single-body type multistage neutralization tank with a partition plate and a partition stirring device inside, the returning material pretreatment device is a fluidized bed pretreatment bin or a rotary ammoniation cylinder, and the production scale of the method is 9-11 ten thousand tons of compound fertilizer per year.

Description

Method for producing urea formaldehyde polyglutamic acid compound fertilizer from phosphorus-potassium mixed acid raffinate Technical Field The application relates to the technical field of fertilizer production and industrial solid waste resource utilization, in particular to a method for producing urea formaldehyde polyglutamic acid compound fertilizer by using phosphoric and potassium mixed acid raffinate. Background Along with the promotion of industrial solid waste recycling policy and the upgrading of the agricultural requirement on high-efficiency functional fertilizers, the phosphorus-potassium mixed acid raffinate is used as a byproduct of phosphorus chemical production, becomes a high-quality low-cost raw material for producing compound fertilizer because of rich phosphorus-potassium nutrients, and becomes a core technical path for improving the utilization rate of fertilizer nutrients and strengthening the field application effect because of the combination of the slow-release nitrogen characteristic of urea formaldehyde and the growth-promoting stress-resistant function of polyglutamic acid. However, the phosphorus-potassium mixed acid raffinate itself has complex components, contains various impurities, has high natural acidity and large fluctuation range, and provides a serious challenge for the stability control of the subsequent process. In the prior art, neutralization reaction is finished by adopting a single step when the compound fertilizer is produced, so that acidity fluctuation of raffinate is difficult to be precisely counteracted, the pH value of a neutralization system is always in an unstable state, and the situation of severe oscillation of local peracid or acid-base often occurs. The subsequent slurry spraying granulation step needs to be subjected to a high-temperature environment, and the polyglutamic acid is used as a bioactive substance, so that under the dual effects of unstable acid-base conditions and high temperature, structural degradation and active group destruction are very easy to occur, and the core functions of promoting growth and resisting stress are greatly weakened. The problem not only causes the waste of functional components, but also causes the dual expectations of slow release and synergy of the final compound fertilizer product to be difficult to fully realize, influences the deep landing effect of resource utilization of the phosphoric-potassium mixed acid raffinate, and also is difficult to fully meet the actual demands of agricultural production on the high-activity functional fertilizer. Disclosure of Invention The application provides a method for producing urea formaldehyde polyglutamic acid compound fertilizer by using phosphoric-potassium mixed acid raffinate, which aims to solve the problems that the activity is easy to be lost due to acid-base fluctuation and high temperature in polyglutamic acid production in the prior art. A preparation method of urea formaldehyde polyglutamic acid compound fertilizer by using phosphoric-potassium mixed acid raffinate comprises the following steps: s1, raw material reaction and mixed acid preparation, namely, after the sulfuric acid reacts with potassium chloride, separating out potassium hydrogen slurry and mixing the potassium hydrogen slurry with phosphoric acid to prepare phosphorus-potassium mixed acid slurry; S2, mixing the neutralization and functional agent, namely carrying out multistage neutralization reaction on the phosphorus-potassium mixed acid slurry, and adding a polyglutamic acid solution in the neutralization process to obtain composite slurry; s3, slowly releasing nitrogen source mixing, namely adding urea formaldehyde into the composite slurry, and mixing to form gunite slurry; S4, returning charge pretreatment and granulation, namely carrying out ammoniation pretreatment on part of the screened fine powder returning charge to obtain pretreated returning charge; s5, screening and packaging, namely drying the wet fertilizer particles, screening, and carrying out spray coating on the combined particles to obtain a compound fertilizer product; s6, recovering the process waste heat, namely recovering and utilizing the chemical reaction heat and/or the absorption heat generated in the manufacturing process. By adopting the technical scheme, the preparation method surrounds the resource utilization of the phosphoric-potassium mixed acid raffinate, and a multi-step collaborative production system is constructed. And (3) carrying out double decomposition reaction on sulfuric acid and potassium chloride to generate potassium hydrogen chloride slurry, separating and recovering hydrogen chloride gas, mixing with phosphoric acid, and preparing into phosphorus-potassium mixed acid slurry with balanced nutrition by means of phosphorus-potassium element accurate proportioning, thereby laying the nutrient foundation of the compound fertilizer. Aiming at the characteristics of complex components and large