Studies On The Preparation Technology Of Soluble Ammonium Polyphosphate Fertilizer

Water resources are scarce in China,and the crisis of water resources is becomingincreasingly prominent.However,agricultural irrigation needs to consume a large amount of water resources.According to statistics,the proportion of agricultural water occupies more than half of the total water in our country,but its comprehensive utilization rate is less than half,while that of developed countries has reached over 70%.Therefore,there is much room for improvement in agricultural water use.Chemical fertilizer is a key factor in agricultural production.The amount of chemical fertilizer used in China is very large,but the effective utilization rate is only about 30%,and a considerable part of the chemical fertilizer has not really played a role.Therefore,it is crucial for the development of agriculture to develop a new type of fertilizer and application technology.The integration of water and fertilizer can reduce agricultural water consumption and improve the effective utilization rate of fertilizer,which is the important direction of agricultural development in the future.The low Degree of polymerization of ammonium polyphosphate has the advantages of good solubility,high nutrient content and near neutrality of pH,it is a good water-soluble new fertilizer with high efficiency.However,the research on the application of agriculture in China is scarce,and the reaction conditions described in the literature are different from the properties of the products.Therefore,it is of great significance to explore the conditions for the synthesis of water-soluble ammonium polyphosphate.The subject draws on the current method of synthesis of ammonium polyphosphate with high polymerization degree,polycondensation reaction with different condensing agents at high temperature,and ammonium polyphosphate obtained after cooling and solidification,and its synthetic process conditions are explored.?1?Ammonium polyphosphate was prepared using urea as an ammoniating agent and a condensing agent.The effects of the ratio of urea and urea phosphate,reaction time and reaction temperature on the degree of polymerization and solubility of ammonium polyphosphate products were investigated by single factor experiments and orthogonal experiments.The results showed that the influence of each factor on the product polymerization degree was different:the ratio of urea to urea phosphate>reaction time>reaction temperature.And the preferential process conditions for the reaction were obtained:The molar ratio of urea to urea phosphate was 0.4:1 and the reaction time was 60 min,the reaction temperature was 230?.The average degree of polymerization of the products is 10.94 and the solubility is 3.70 g/100 gH₂O.FTIR and XRD analysis of the products under this condition proved that the product was ammonium polyphosphate.?2?Ammonium polyphosphate was prepared with melamine as the ammoniating agent.The effects of reaction temperature,reaction time,ratio of urea phosphate to melamine on the degree of polymerization and solubility of ammonium polyphosphate products were investigated by single factor experiments and orthogonal tests.The results showed that the influence of each factor on the product polymerization degree was different:reaction temperature>the ratio of urea phosphate to melamine>reaction time.And the preferential process conditions for the reaction were obtained:The reaction temperature was 220?and the reaction time was 75 min,the molar ratio of urea to urea phosphate was 12:1.The average degree of polymerization of the products is 14.67 and the solubility is 3.62 g/100 gH₂O.FTIR and XRD analysis of the products under this condition proved that the product was ammonium polyphosphate.?3?Ammonium polyphosphate was prepared by urea phosphate-phosphorus pentoxide polymerization.The effects of the ratio of urea phosphate and phosphorus pentoxide,reaction time and reaction temperature on the degree of polymerization and solubility of ammonium polyphosphate products were investigated by single factor experiments and response surface experiments.The results showed that the influence of each factor on the product polymerization degree was different:the ratio of urea phosphate to phosphorus pentoxide>reaction time>reaction temperature,and the interaction between factors was not significant.And the optimal reaction conditions were obtained:The molar ratio of urea phosphate to phosphorus pentoxide was 4.44:1and the reaction temperature was 218.93?.The reaction time was 70.82 min.The average degree of polymerization of the products is 23.64 and the solubility is 2.24g/100 gH₂O.FTIR and XRD analysis of the product obtained under optimal conditions confirmed that the product was a crystalline type I ammonium polyphosphate.