Urea granulation technology
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Gentlemen, that person used urea for extrusion granulation. What should be taken into account when granulating with urea, such as moisture control and particle size?
Do you mean to directly compress urea powder to form urea particles? It seems like they all crush urea pellets, right?
Reply to 2# Fengfeng Laonong: After crushing the urea granules, they are pressed into granules together with other fertilizers such as monoammonium phosphate.
Could the original poster describe in detail the process you mentioned?
Reply to 3# wdsh1: The fertilizer pellets produced using this method have very poor strength, and moisture levels cannot be controlled.
Oh, haha, I see now. It’s just the extrusion granulation of compound fertilizers. Which extrusion method do you use? If it is roll extrusion, it is recommended not to use a particle size that is too small. 3~4mm might be more appropriate. The strength of the particles depends to a large extent on moisture control. If it is too dry, the particles will inevitably be loose and have low strength. So, generally speaking, some water needs to be added. Of course, the moisture content cannot be too high, otherwise it will not meet the factory specifications. You need to conduct more experiments to determine how much water should be added to the material based on the local level of air humidity. In humid areas in the south or during rainy weather, it may not be necessary to add water.
Reply to 6# Fengfeng Lao Nong: The process is relatively simple – feeding – crushing – metering – mixing – granulation – drying – coating – packaging. Is it appropriate to control the moisture level at 20~30?
Do you produce sulfur-coated slow-release fertilizers? Why is there still a lamination step? Generally, drying is not required in the production of compound fertilizers via extrusion granulation; the moisture content after granulation should be appropriate. Otherwise, extrusion granulation would be meaningless. Since all the energy used in extrusion granulation is devoted to the extrusion process, if additional energy is required for drying, the cost will increase significantly, which would not be worthwhile. In that case, it’s better to use a drum or disk granulator. The standard GB15063-2009 for compound fertilizers requires that the moisture content upon leaving the factory be within 2%.
The terms \"drying\" and \"coating\" may not be entirely appropriate; since it is impossible to ensure an adequate level of moisture, drying is still necessary. After drying, waxing and coloring are carried out in a roller machine.
What type of extrusion do you use? Opposing rollers? Flat die? Ring die? There are just these few types. Logically, there is no need for drying. Are your raw materials urea, monoammonium, potassium chloride, or potassium sulfate? If it’s just these materials and roll compression is used, then when the air is relatively dry, add a little water during mixing so that the moisture content is around 2% (within 2%), and then proceed with compression and granulation. The resulting hardness will be ideal; the product can be packaged and shipped right away without the moisture level exceeding the specified limit. Because friction generates some heat during extrusion, which helps to remove a little moisture.
Reply to 10# Fengfeng Lao Nong: Thank you! Let’s give it a try to see if we can eliminate the drying.