Study On The Preparation Technology Of Urea Formaldehyde Slow-Release Compound Fertilizer

The urea formaldehyde slow-release fertilizer is one of the slow sustained-release fertilizers with great potential, but there are many blank and weak links in research and applications of urea formaldehyde slow-release fertilizer, such as the industrialized production technology is still not mature, the research of urea formaldehyde slow-release fertilizer in-depth is necessary.In this study,the various factors which influence the conversion ratio of nitrogen and product activity index—AI are inspected by single-factor experiment,and the appropriate preparation conditions of urea formaldehyde slow-release fertilizer is obtained, the mother liquor are recycled repeatedly to inspecte the change of nitrogen production rate and product activity index—AI; the potassium chloride is added to prepare slow-release compound fertilizer in the process of preparing urea formaldehyde slow-release fertilizer,and to inspecte the influence on the preparation of urea formaldehyde slow-release compound fertilizer of adding period and adding amount of potassium chloride.The results show:1.The appropriate technological parameters of preraring urea formaldehyde slow-release fertilizer are:n(U)/n(F)=1.4; the conditions of hydroxymethylation are t1=90min,T1=50℃,pH1=8.0; the conditions of methylenelation are t2=75min,T2=40℃, pH2=3.0; dryin g temperature of product is 90℃.Under these conditions, the product activity index—AI is 53.16%, and the conversion of nitrogen is 75.07%.2. After 5 times of recycling the mother liquor,the product activity index—AI falls from 53.16% to 48.30%,but it still meets the standards formulated by AOAC,that is AI≥40%; the nitrogen production rate increase markedly after the mother liquor is recycled once, although the nitrogen production rate decrease after the first recycle,the measure of recycling the mother liquor reduce waste of resources and discharge of waste liquid with economic significance and environmental protection significance.3.When the adding amount of potassium chloride constant,the product activity index——AI is highest when the potassium chloride is added at the end of the reaction,the potassium chloride is added at the beginning of methylenelation and hydroxymethylation,in that order,follow the way of the potassium chloride is added at the end of the reaction;in the circumstances of the potassium chloride is added at the beginning of methylenelation and hydroxymethylation,the conversion ratio of nitrogen and the product potassium content are almost the same,when the potassium chloride is added at the end of the reaction,the conversion ratio of nitrogen and the product potassium content are less than above two circumstances.When the adding period constant,the product activity index——AI decrease with the increase of the adding amount of potassium chloride;the nitrogen production rate dose not change with the adding amount of potassium chloride;the product potassium content increase with the increase of the adding amount of potassium chloride.The experimental rule of adding potassium chloride experiment shows that it is inappropriate to add the potassium chloride in the process of preparing urea formaldehyde slow-release fertilizer.