Sulfur coating technology is a kind of microcrystalline polymer material with sulfur and paraffin as main raw materials on the basis of large granule urea, so as to achieve slow controlled release of nitrogen nutrients. Sulfur coated urea should meet the following three indicators:
1. The content of N was 31 / 34 / 35 / 37.
2. Under the condition of 38 ℃ still water and constant temperature, 10%, 15%, 20% and 25% of total nitrogen content were released in 24 hours.
3. 60% - 70% of total nitrogen was released in seven days.
The key technology of sulfur coated urea coating can be used in NPK fertilizer granulation, drum granulation and other slow and controlled-release fertilizers, realize curtain coating granulation of various solid granular fertilizers, and produce various slow and controlled-release fertilizers such as super granular urea, sulfur coated compound fertilizer, lignosulfonate urea, humic acid urea and water-soluble resin.
The coated controlled-release fertilizer can give full play to the fertilizer efficiency and utilization rate, and has important economic and ecological benefits. NPK fertilizer manufacturing process adopts coating treatment, which greatly improves the controlled release time of fertilizer. The controlled release time of coated controlled-release fertilizer can be as long as 3 months to 2 years due to the technology setting, which is called slow-release fertilizer, long-term coated fertilizer and coated controlled-release fertilizer.
Because the efficiency of coated controlled-release fertilizer can be increased by 1-2 times than that of general fertilizer, and about one third of nitrogen fertilizer can be saved when it is used in rice farming. If we calculate the cost of fertilizer, the loss of fertilizer, the amount of fertilizer, labor and environmental protection are more important. The price difference between the two has been reduced obviously. The prospect of coated fertilizer processing by fertilizer manufacturing equipment still has its advantages and merits.