Studies On The Preparation Of Anti-caking Agent And Its Anti-Caking Property For Compound Fertilizer

Fertilizer plays an important role in increasing crop yield.However,due to various reasons,fertilizer is prone to agglomerate,which is inconvenient for agricultural production.In particular,because of the complex composition and high nutrient content,the compound fertilizer is easy to agglomerate in storage,transportation and application,what hinder its use,and even affect its fertilizer efficiency.In this paper,the compound fertilizer by spraying and melting granulation were studied.The reason of caking was discussed,and an effective anti-caking agent was developed accordingly.Details are as follows:Firstly,the moisture absorption properties of two kinds of compound fertilizers by melting and spraying granulation were studied.The temperature and humidity conditions of these compound fertilizers were obtained by the determination of the absorption rate curve,which were 50?,70% and 40?,70% respectively,when they were used in rapid agglomeration test.A kind of improved method of rapid characterization of granular fertilizer caking which can objectively reflect the environment of compound fertilizer in the process of storage and transportation was used in this experiment.And the period of experiment could be shorten from seven weeks to only one week.Therefore,the evaluation efficiency of caking was improved.Secondly,the internal factors and external factors that affect the caking of compound fertilizer with spray granulation were studied.The experimental results showed that the moisture content and the moisture absorbed from environment were the direct causes of caking of compound fertilizer,the environmental temperature,humidity and storage pressure were the driving forces of caking of compound fertilizer.By the analysis of various influencing factors,when the fertilizer water content lower than 0.8%,the small particle content less than 10%,the air relative humidity less than 50%,the pressure lower than 2 kg/cm2,the compound fertilizer was not easy to form agglomerate.In addition,the storage time also should be reduced.Thirdly,a kind of natural macromolecule anti caking agent was prepared,which was easy to be prepared and biodegraded.And the mechanism of anti-caking was discussed.The effects of the preparation of raw material,the concentration of anti-caking agent and the amount of the anti-caking spraying on fertilizer were investigated.The best ratio of the anti-caking agent compounded with hydroxyethyl cellulose(HEC)and the twelve sulfonate(LAS)was 0.5.The anti-caking effect was better when the concentration of anti-caking agent was 20%,the spraying amount was 3‰,which was more than 87%.Finally,the effect of slow-release fertilizer which was coated with the anti-caking agent was studied.The aqueous solution immersion method showed that the release rates of N,P and K were 35.4%,23.5% and 27.9%,respectively,which were lower than that of the untreated compound fertilizer at the rate of 46.8%,31.2% and 34.7%,respectively,after soaking in aqueous solution for a week.The soil culture method showed that the release rate of N,P and K in the 50 days of the compound fertilizer coated with anti-caking agent was70.3%,60.5% and 61.7%,respectively,which were lower than that of the untreated compound fertilizer,at the rate of was less than 86.6%,76.3% and 75.8%.These two methods showed that the anti-caking agent has good slow-release effect as a coating material.