1. Product Introduction

The Drum Spray Granulator typically takes the form of a massive horizontal rotating drum. It serves a dual purpose: acting as both a high-efficiency granulator and, in specific processes, a partial dryer.

• Applications: Primarily used for the production of Di-ammonium Phosphate (DAP), Mono-ammonium Phosphate (MAP), urea-based compound fertilizers, and various chemical products that require a direct phase transition from liquid slurry to solid granules.

• Industrial Role: This is the cornerstone equipment for large-scale fertilizer plants (with an annual capacity exceeding 100,000 tons) to achieve continuous, automated production.

2. Performance Features

Utilizing the unique "slurry-to-film" coating characteristic, spray granulation offers significant advantages in finished product quality:

• Dense Granule Structure: Granules are formed by "painting" layers of slurry onto seed nuclei, creating an "onion-like" concentric structure. This results in exceptionally high granule strength and resistance to crushing.

• Low Moisture Content: Because the granulation process involves simultaneous heat exchange with a carrier (such as hot air), much of the moisture is evaporated during formation, reducing the workload for downstream drying stages.

• Superior Aesthetics: The process produces highly spherical granules with a smooth surface and uniform color, providing strong market competitiveness for the end product.

• Large-Scale Production: With high single-unit processing capacity, it meets the demands of ultra-large factories for 24/7 continuous operation.

• High Raw Material Recovery: The system easily processes recycled fines and scrubbing liquids, enabling a closed-loop production cycle with zero waste.

3. Working Principle

The core of spray granulation lies in the continuous cycle of "Slurry Atomization" and "Seed Coating."

Core Process Stages:

1. Seed Bed Formation: A specific volume of small "seed granules" (usually provided by system recycle) is fed into the drum. As the drum rotates, internal lifting flights lift and drop these seeds, creating a continuous "material curtain."

2. Slurry Spraying: High-temperature, high-concentration slurry prepared via chemical reaction is atomized through high-pressure pumps and spray guns, then sprayed evenly onto the tumbling material curtain.

3. Coating & Growth (Onion-Style): Atomized slurry droplets adhere to the surface of the cooler seed granules and spread rapidly. As the granules rotate between the spraying zone and the drying zone, the slurry solidifies layer by layer. The granules grow in size much like a "rolling snowball."

4. Heat Exchange & Drying: Hot air is typically introduced into the drum. As the slurry solidifies, the moisture is simultaneously carried away by the airflow.

5. Overflow Discharge: As granules reach the target size and more material is added, the finished granules overflow from the end of the drum, moving toward the screening and cooling stages.