The process of the NPK fertilizer production line
is essentially to crush (melt) each single raw material separately, and then formulate a raw material ratio plan (including selecting a certain proportion of additives) according to the requirements, and carry out mixing, granulation, drying, cooling, screening, Packaging etc. The core of compound fertilizer production is granulation. Once the granulation process and equipment are determined, the preparation and proportioning of the previous raw materials, and the subsequent process requirements for drying, cooling, and screening are determined accordingly. After more than 10 years of continuous exploration in the production of compound fertilizer in my country, on the basis of the above-mentioned conventional compound fertilizer production line technology, according to the production, special requirements of product technical indicators and raw material supply, the main classifications according to the granulation process are: agglomerate method, slurry method , Melt granulation method, blending method, extrusion method, coating granulation method, etc. Various production processes have the characteristics of coexisting development in different periods of compound fertilizer development. According to the production characteristics of compound fertilizers in different periods, they can be divided into three stages:
The stage was the mid-1980s. Various regions developed small-scale compound fertilizer production, with an annual output of about 5,000 tons, mainly in the form of extruded strips and large granular particles. Some manufacturers first granulated phosphorus and potassium fertilizer and then blended it with urea. Due to many shortcomings, only a few manufacturers are producing it now.
The second stage is from the late 1980s to the early 1990s. The development of compound fertilizer manufacturers with an annual output of more than 10,000 tons is mainly in granular form. The process of NPK fertilizer production includes disc granulation and drum granulation. The granulation method has its own advantages and disadvantages. The disc granulation method is relatively intuitive, and the disc is easy to operate after the inclination angle and speed of the disc are stable; its disadvantage is that the process is long, it occupies a lot of land, and the labor intensity of workers is large, and a binder needs to be added to granulate. The disc granulation method is suitable for the production of compound fertilizer with an annual output of 10,000 tons or less. The drum granulation method is used in the production of compound fertilizers of more than 10,000 tons. Its advantage is that it takes less area and the labor intensity of workers is less. The disadvantage is that the steam contains 40%-50% water, which is very difficult to calculate the water content of the material. Difficult to master, workers need to operate with experience. In the second stage, most of the ternary compound fertilizers with a total effective nutrient content of ≥25% are produced.
The third stage was in the 1990s, especially in the late 1990s. With the development of agricultural production, farmers needed compound fertilizers with higher nutrient concentrations. The total effective nutrient content of N, P, and K was ≥40%, and there was a lack of soil in many areas. For the symptoms of calcium, magnesium, sulfur and other medium elements, relying only on the large elements of nitrogen, phosphorus, and potassium can no longer meet the needs of agricultural production. At this time, a large number of enterprises producing high-concentration ternary compound fertilizer appeared. The NPK fertilizer production process of most enterprises adopts agglomerate method, slurry method, melt granulation method, coating granulation method.
In the fourth stage, entering the 21st century, compound fertilizer production line companies have made considerable progress. The concentration of compound fertilizer is developing towards higher concentrations, especially the development of balanced fertilization technology. Production companies have begun to develop special fertilizer production technology. At this time, blended fertilizers are also once again. The development is also mainly towards high concentration.