When NPK fertilizer is produced, if the phosphorus source in NPK is heavy calcium and common calcium, the fertilizer efficiency varies with the concentration. The main reason is that superphosphate reacts with phosphoric acid to reduce the fertilizer efficiency. It is better not to use heavy calcium as phosphorus source, but to ammoniate heavy calcium and then use it to produce NPK compound fertilizer.
The basic equipment for NPK fertilizer production includes: batching system, mixer, fertilizer granulator machine, drying cooling system, screening machine, coating machine, packing machine.
The key point of NPK fertilizer production is the processing of raw materials. In production, different raw materials should be mixed according to the proportion, and then made into crop-specific NPK compound fertilizer. In the production of NPK compound fertilizer, raw materials need to be stirred before entering the granulator machine. If the NPK fertilizer is not uniformly mixed, the nutrients in different parts of the compost pile will be different. Some nutrients content is not enough, but some nutrients content is too much. Finally, the nutrients of NPK fertilizer granules are inconsistent when the material enters the fertilizer granulator machine, so the nutrients of NPK fertilizer granules are not comprehensive.
NPK fertilizer can be granulated by rotary drum granulator machine or fertilizer disc pelletizer machine. After the material is granulated by the fertilizer granulator, the physical properties of the fertilizer are better and it is easy to apply. The size of compound fertilizer particles is relatively uniform and hygroscopicity is small, so it is easy to store. The granular fertilizer made by fertilizer granulating machine is more suitable for large-scale mechanized application and reduces labor force. Compound fertilizer has few by-components, and its nutrients are basically needed by crops, which can avoid adverse effects on soil. Moreover, NPK fertilizer is produced according to the nutrient characteristics of crops and soil nutrients, so as to avoid the waste of nutrients and improve the effect of fertilizer production.