The suitable temperature range for the drying stage in the organic fertilizer production line is typically between 80°C and 120°C. The core principle is to quickly remove moisture while avoiding high temperatures that could damage beneficial microorganisms and nutrients in the organic fertilizer.

This temperature range is not a fixed value and must be adjusted flexibly based on the raw materials of organic fertilizers, moisture content, and the type of drying equipment.

1. Core Basis for Temperature Setting

Temperature settings primarily revolve around two objectives: "Maintenance" and "Fast Drying," with specific considerations based on the following factors:

• Raw material characteristics: Different raw materials have varying high-temperature resistance. For instance, organic fertilizers primarily composed of livestock manure and straw can withstand relatively higher temperatures, typically controlled between 100°C and 120°C. In contrast, organic fertilizers rich in microbial residues and humic acid, due to their higher content of active substances, require slightly lower temperatures, generally ranging from 80°C to 100°C.

• Initial Moisture Content: If the initial moisture content of the pellets after granulation is higher (e.g., 35%-40%), the temperature can be appropriately increased (e.g., 110°C-120°C) to enhance drying efficiency. Conversely, if the initial moisture content is lower (e.g., 25%-30%), the temperature can be reduced (e.g., 80°C-100°C) to avoid excessive drying.

• Drying Equipment Types: Different equipment types exhibit varying heat transfer efficiencies and temperature settings.

2. Key Principles of Temperature Control

• No overheating: When the temperature exceeds 130°C, beneficial microorganisms in organic fertilizers (such as nitrogen-fixing bacteria and phosphorus-solubilizing bacteria) will die in large numbers, while some organic matter (like humic acid) will be carbonized, leading to a significant decline in fertilizer efficacy.

• Prioritize low-temperature slow drying: Under the premise of ensuring drying efficiency, prefer lower temperatures and longer durations to fully retain the active components and nutrients of organic fertilizer.

• Tail-end temperature monitoring: In addition to the inlet temperature of the drying equipment, special attention should be paid to the outlet (flue gas) temperature, which is typically maintained at 50°C-60°C. At this point, the particle moisture can generally be reduced to 20%-30%, meeting the requirements for subsequent cooling and packaging.