In the NPK fertilizer production line, the drying process is a crucial link between granulation and packaging. Its core function is to remove excess moisture from the granulated fertilizer, controlling the moisture content within the standard range of 8%-12% to prevent clumping and mold growth, while retaining nitrogen, phosphorus, and potassium nutrients. This directly determines the fertilizer's quality and shelf life.

The drying process must follow the principle of "gradual and precise temperature control," and mainly consists of three core stages. First, pretreatment involves screening and removing impurities from the NPK fertilizer granulator machine, ensuring uniform particle size and sufficient heat penetration.

The core drying stage employs segmented temperature control: initial preheating at medium to low temperatures to prevent granule cracking and nutrient decomposition caused by high temperatures; medium-stage drying at a controlled temperature of 80-100℃ at a uniform speed to gradually remove moisture; and final drying at a lower temperature to stabilize the moisture content.

The key to this process lies in parameter control. The drying time, temperature, and hot air velocity of the drum fertilizer dryer must be flexibly adjusted according to the fertilizer particle size and formula differences to avoid uneven drying due to accumulation. After drying, cooling is necessary to prevent residual heat from causing moisture reabsorption. Once the product meets the standards, it can proceed to the packaging stage.

This drying process ensures uniform fertilizer particle size while maximizing nutrient retention, making it suitable for large-scale NPK fertilizer production and an indispensable quality assurance link in the production line.