Sulfur-coated urea controlled-release fertilizer as well as preparation method thereof

Abstract

Disclosed are a sulfur-coated urea slow-release fertilizer and a preparation method therefor. The method comprises the steps: 1) coating pre-heated base material urea particles by using molten sulfur, so as to obtain a compact and uniform coated-layer with a preset thickness; 2) coating, by a pump, a sulfur-coated layer prepared in the step 1) by using a composition consisting of natural beewax, so as to improve the tenacity and the slow release of the sulfur-coated urea; and step 3) gradually cooling the natural beewax composition-coated sulfur-coated urea particles processed in step 2) by using a fluidized bed cooler and a solid heat exchanger, so as to ensure that the organic waxy films are compact and mutually connected. The method provided in the present invention improves the nitrogen content in the fertilizer, and reduces the content of the coated sulfur, and has very good controlled-release property and good tenacity. Nutrients of the product can be released according to demands of growth stages of crops. The fertilizer has improved impact resistance and abrasion performance and are not affected by transport, collision and blending, and can be completely degraded, is safe and environmentally-friendly, and the price of the fertilizer is also accepted easily by a user.

Description

technical field [0001] The invention relates to a urea slow-release fertilizer and a manufacturing method thereof, in particular to a sulfur-coated urea slow-release fertilizer and a manufacturing method thereof. release fertilizer. The sulfur-coated urea slow-release fertilizer product of the invention has good controlled release and good toughness, improved impact resistance and wear resistance, can be completely degraded, and is safe and environmentally friendly. Background technique [0002] Sulfur-coated urea (SCU) slow-release fertilizer, first developed by TVA in the United States in 1957, is a relatively mature slow-release fertilizer. In the conventional method of manufacturing sulfur-coated urea, granular urea with a nominal size range of 1.7-2.9mm has been preheated at 70-80 degrees Celsius in a fluidized bed heater, and then added to a rotating horizontal drum-shaped drum (the 12 feet long and 5.5 feet in diameter). At this time, the lifting scrapers or longit...

AI Technical Summary

Problems solved by technology

Due to its composition characteristics, although the product made of it as a sealant was well sealed at the time, it was easily broken and broken during packaging, transportation, and mixing before use, and even the phenomenon of defilming occurred, resulting in incomplete sealing of the product , poor nutrient release

And the traditional use of hydrocarbon wax needs a long process to degrade in the soil due to its composition, and long-term and large-scale use will have a certain impact on the soil structure and the natural environment (from "Journal of Ecotoxicology", Volume 3, No. 1, February 2008 Issue "Research Progress on Microbial Degradation and Remediation of Total Petroleum Hydrocarbon Pollution (TPH) in Soil")

[0006] Although these sulfur-coated urea products generally have good sustained-release properties after being manufactured, the impact resistance and abrasion resistance of the coating are low, and the coating will occur after handling, transportation, blending and coating operations. Mechanical degradation, resulting in poor slow-release performance, unable to supply nutrients for a long time according to the nutrient requirements during the growth of crops, and some sealants cannot be completely degraded in a short period of time, there are certain environmental problems, and the price is expensive

And some patents publish a layer of polymer on the sulfur layer, which has good release and impact strength, such as US5599374, but the price is expensive, the operation is also more complicated, the sulfur content is high, and the nitrogen content is low, which is difficult to be accepted and exists. Environmental issues, non-degradable

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