Developing Of Coated Urea By Urea-aldehyde And Test Of Its Characteristics

Slow-release urea of urea-aldehyde has three shortcomings that nutrient releasing is more slowly,the using amount of aldehyde is too much and the price is too expensive.In view of the above question,this research discussed the feasibility of the two methods of producing coated-slow/controlled-urea using urea-aldehyde by using dissolve rate in water .One way is sprayed-coated-urea using aldehyde,another is sprayed-coated-urea using urea-aldehyde.The productions that had reached the international recongnized standard were appreciated further by soil-column leaching,and compared the produce cost with other similar production in market. The results as following:1.Developing of coated-urea by urea-aldehyde.(1)Developing of coated-urea using spraying method of aldehyde:first,Attain a conclusion of the better reacted condition of urea and aldehyde by reaching reacted condition of urea and aldehyde.It is that formaldehyde:reacted temperature 70～80℃,reacted pH 2～3,reacted time 45min,mol ratio between urea and formaldehyde 6:1～3:1;acetaldehyde:reacted temperature 60～70℃,reacted pH2～4,reacted time 30min,mol ratio between urea and acetaldehyde 6:1～3:1;isobutyraldehyde:reacted temperature 60～70℃,reacted pH 2～3,reacted time 30min,mol ratio between urea and isobutyraldehyde 6:1～3:1.Developed nine coated-urea using spraying method of aldehyde under this condition.They are FSU-1,FSU-2,FSU-3,ASU-1,ASU-2,ASU-3,ISU-1,ISU-2 and ISU-3.(2)Developing of coated-urea using spraying method of urea-aldehyde.the material is the coated-material is urea-formaldehyde produced under this condition of reacted temperature 70～80℃,reacted pH 2～3,reacted time 20min,mol ratio of urea to formaldehyde is 1.5:1;urea-formaldehyde-acetaldehyde produced under this condition of reacted temperature 70～80℃,reacted pH 2～4,reacted time 20min,mol ratio of urea to formaldehyde to isobutyraldehyde is 2.5:1:1;urea-formaldehyde- isobutyraldehyde produced under the condition of reacted temperature 70～80℃,reacted pH 2～4,reacted time 20min,mol ratio of urea to formaldehyde to isobutyraldehyde is 2.5:1:1.Developed nine coated-urea using spraying method of urea-aldehyde under these condition.These are SRU-UF1,SRU-UF2,SRU-UF3,SRU-UFA1,SRU-UFA2,SRU-UFA3,SRU-UFI1,SRU-UFI2 and SRU-UFI3.2.Characteristic test of coated-urea using spraying method of aldehyde. The result indicate that it is impossible to produce coated-slow-release-urea by spraying formaldehyde, acetaldehyde,isobutyraldehyde onto the surface of urea by test using...