Development Of AZF Technology For The Production Of Granular Water Soluble Fertilzer

Fresh water resources are scarce in China,and the utilization level of agricultural water is low following with serious waste.In addition,the consumption of chemical fertilizer is large and the utilization rate is low.Water soluble fertilizer is suitable for the application of water and fertilizer integration technology,which can save water resources,improve the utilization rate of chemical fertilizer and reduce environmental pollution.Therefore,developing a technology for large-scale production of water-soluble fertilizers has great practical significance.In this paper,the factors that affect the solubility of compound fertilizer in AZF process are studied by analysis and experiments,which are proved mainly leading by the impurities brought in by the raw material for agricultural potassium sulfate and wet process phosphoric acid.Through using water soluble potassium sulphate instead of agricultural potassium sulfate,and using 72% content of ammonium phosphate instead of most wet phosphoric acid,replacing partial ammonium nitrate by potassium nitrate.The content of water insoluble substance can be reduced from 2.0% to 0.5%,but the trace elements in the form of sulfate can not be added.The metal ions in the fertilizer are chelated by the chelating agent,to transform the insoluble phosphate and sulfate into water-soluble trace elements.This study shows that the chelating rate of magnesium,zinc or manganese by using sodium citrate can reach 70%,and 30% for iron or aluminum.The chelating rate of ammonium polyphosphate to zinc,iron or aluminum can reach 35%,and more than 50% for magnesium or manganese,respectively.The chelating rate by using sodium tripolyphosphate is similar to that of ammonium polyphosphate.Adding 37 kg/t chelating agent into the fertilizer and the pH of fertilizer was controlled around 6.0,the production of 17-17-17 nitro potassium sulfate water soluble fertilizers are coincidence with the requirements of HG/T 43605-2012 water solublefertilizer standard.The water insoluble contents in 17-17-17 compound fertilizer are reduced from 2.0% to 0.1%-0.2%,and the contents of water soluble iron and zinc are more than 0.2%.Field experiment results show that 17-17-17 granular water-soluble fertilizer can meet the requirements of water-soluble fertilizers for dripping irrigation under film,greenhouse and other facilities.Compared with powdered water-soluble fertilizer,granular water soluble fertilizer can increase the yield of cotton,eggplant and tomato by 4.53%,0.60% and 0.75%,respectively.