SOP Fertilizer: Essential Potassium Source for Sustainable Agriculture

SOP fertilizer (Sulfate of Potash) is one of the most important potassium fertilizers used in modern agriculture. It provides both potassium (K₂O) and sulfur (S)—two vital nutrients that improve crop yield, quality, and resistance to stress. Compared with other potassium fertilizers, SOP fertilizer contains no chloride, making it ideal for crops sensitive to salinity such as tobacco, potatoes, fruits, and vegetables.

What is SOP Fertilizer?

SOP fertilizer, chemically known as potassium sulfate (K₂SO₄), is a white crystalline salt that dissolves easily in water. It is widely used in both organic and conventional farming. Because it delivers potassium and sulfur simultaneously, it supports both plant growth and protein synthesis, ensuring higher crop quality.

Nutrient	Content	Function
Potassium (K₂O)	50–52%	Enhances crop strength, sugar formation, and water regulation
Sulfur (S)	17–18%	Promotes amino acid and enzyme formation

Benefits of Using SOP Fertilizer

1. Improves Crop Quality – Increases sugar content in fruits and enhances color, taste, and storage quality.

2. Enhances Disease Resistance – Strengthens plant cell walls and improves drought and pest resistance.

3. Chloride-Free – Safe for salt-sensitive crops such as grapes, citrus, and coffee.

4. Suitable for All Soils – Especially effective in arid or saline-affected areas.

SOP Fertilizer Production Process

The SOP fertilizer production process mainly adopts the Mannheim method, which uses potassium chloride (KCl) and sulfuric acid (H₂SO₄) as raw materials. Through high-temperature reaction, cooling, granulation, drying, and packaging, the process transforms raw chemicals into high-quality sulfate of potash granules suitable for agricultural use.

1. Feeding and Reaction Stage

The process begins with potassium chloride being transferred from the automatic feeding hopper through a screw conveyor into the Mannheim furnace. At the same time, concentrated sulfuric acid is precisely added by a dosing pump connected to a corrosion-resistant storage tank.

Inside the Mannheim furnace, the two materials react at 600–700°C, generating molten potassium sulfate and gaseous hydrogen chloride (HCl). A gas collecting hood positioned above the furnace captures the acid gas and sends it to the acid absorption tower for purification. This closed system minimizes emissions and ensures a clean production environment.

2. Cooling and Crushing Stage

After the chemical reaction, the hot molten SOP is discharged from the furnace and sent to a rotary cooler or air cooling system, where it solidifies into crystalline particles. The cooled material is then conveyed to a chain crusher or hammer mill for size reduction. This ensures uniform particle size before entering the granulation section.

3. Granulation and Drying Stage

The finely ground SOP powder is evenly fed into a double roller granulator (or sometimes a disc granulator, depending on production needs). Inside the granulator, the material is moistened and agitated, forming uniform spherical granules.

The moist granules are then transferred to a rotary drum dryer, where hot air removes excess moisture, improving the mechanical strength of the particles. A rotary cooler positioned downstream helps stabilize granule temperature before further processing.

4. Screening and Coating Stage

Once dried, the granules pass through a vibrating screen machine, which separates them into qualified and unqualified fractions. Oversized particles are returned to the crusher for reprocessing, while fine powder is recycled to the granulator.

In some production lines, a rotary coating machine is used to apply an anti-caking or moisture-resistant film, improving the storage and flow properties of the SOP fertilizer.

5. Packaging and Storage Stage

The final granules are conveyed by a belt conveyor to the automatic weighing and packaging machine, where they are precisely bagged according to the required weight. The PLC-controlled packaging system ensures consistency and reduces labor intensity.

After packaging, the bags are sealed, labeled, and stacked by an automatic palletizer, ready for shipment or warehouse storage.

This SOP fertilizer production process integrates advanced equipment such as Mannheim furnaces, disc granulators, rotary dryers, and PLC-controlled packaging lines to ensure efficient, continuous, and environmentally friendly operation. By integrating automation and dust removal systems, this production line achieves high production efficiency, stable product quality, and minimal environmental impact, meeting the growing global demand for high-purity, chlorine-free potassium fertilizers.

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