Preparation And Properties Of Slow-release Potassium Fertilizer

According to the existence of the excessive loss of potash in the process of using, the experimental research preparation of slow-release potash was carried out. This thesis adopts three methods to prepare slow-release potash to improve the comprehensive utilization of potassium feldspar resources and explore the new method of preparing slow-release potash.1. The silica gel method is using Na2 Si O3 to prepare a certain acidity and stability of silica gel, then adding the K2SO4 into the silica gel to react a certain time for the samples. There are some small flocculent particles on the surface of the samples. The best coated sample without centrifugal separation is at the condition of 50℃ for preparing silica gel and coating, Na2 Si O3:K2SO4=2:1. However, by the Si element dose not crystallize because of the Na element. The coating layer of the samples after centrifugal separation and washing Na+, is obviously increased and the properties of K2SO4 are not changed.2. Physical immersion method makes full use of the pore on the surface of the Si O2 adsorbing the K2SO4 as to achieve some the slow-release effect. The method is that adding Si O2 into the saturated solution of K2SO4 for samples. Characterized by a variety of means shows that the K+ into the pore of the Si O2. With the increasing of immersion time the content of potassium increases rapidly to the maximum, then decrease rapidly and approximately constant with the extension of time. The maximum of potassium content of the immersion time is 6 hours, and the content is about 0.5%. The XRD analysis of the samples shows that the properties of the treated Si O2 are not changed.3. The coating-machine method is using the production process of the coating machine to make inorganic coating materials and organic coating materials for coating experiments. The changes of the sample are found by the analysis. The samples prepared by the inorganic coating, appear flocculent particles, however K element in samples with Na element to generate composite salts. Si does not crystallize. The surface of the samples prepared by the organic coating is obviously covered by a layer of sticky material. The effect of coated organic coating is more uniform than inorganic coating.4. Through the study of the preparation of the samples, shows that the samples prepared by the silica gel method and the samples prepared by the coating-machine have some slow release properties. The samples are prepared by the silica gel method at the condition of 50℃ for preparing silica gel and coating, Na2 Si O3:K2SO4=1:1 are the best. The release rate of the samples prepared by the coating machine is 50% in 24 h. The samples prepared by the physical immersion method do not have slow-release properties.