Smart screening for sustainable fertilizers

The fertilizer industry continues to evolve under the combined pressure of rising global demand, increasingly variable raw material quality, and tightening environmental and product regulations. Producers are expected to supply fertilizers that are not only chemically effective, but also physically consistent, safe to handle, and compatible with modern application technologies. Within this environment, screening has taken on a central role in fertilizer processing.

Once regarded primarily as a final classification step, screening is now understood as a critical control function that influences product quality, energy consumption, plant availability, and overall process stability. Screening decisions affect how raw materials are prepared, how granulation and recycle loops are balanced, and how finished products behave during storage, packaging, and transport. When examined from a mine-to-market perspective, screening acts as a connecting element that aligns upstream extraction and processing with downstream logistics and end-use requirements.

Screening as a function of material properties

Fertilizer materials display a wide range of physical and mechanical properties. Particle size distribution, shape, moisture content, bulk density, abrasiveness, thermal sensitivity, and hygroscopic behaviour all influence how a material performs on a screen. As a result, screening efficiency cannot be optimised through equipment selection alone; it requires a thorough understanding of material behaviour under dynamic conditions.

An instructive approach to screening begins with material characterisation. Laboratory analysis and pilot testing help determine parameters such as flowability, tendency to agglomerate, and sensitivity to vibration. These characteristics directly inform screen type, motion, inclination, and media selection.

Understanding the mechanical behaviour of each product type is essential for identifying the optimal screening technology and improving downstream processing steps.

Linear vibrating screens for dry, granular fertilizers

Dry mineral fertilizers benefit particularly from vibration-based linear vibrating screening systems. These screens operate with a defined vibration direction that promotes stratification within the material bed. As the material moves across the deck, finer particles migrate downward and pass through the apertures, while coarser particles remain on the surface and are conveyed towards the discharge point.

These screens offer:

• High separation accuracy.
• Stable throughput across a wide operating range.
• Sharp cut points and clear differentiation between oversize and undersize fractions.

In fertilizer plants, linear screening is commonly used for both intermediate and final classification. In granulation circuits, for example, screens regulate the proportion of on-size product relative to recycle streams. Oversize granules are crushed and returned to the granulator, while undersize material is recycled directly.

The effectiveness of this screening step has a direct impact on process efficiency. Excessive recycling increases energy consumption, accelerates wear on crushers and granulators, and destabilises thermal balance in drying systems. Accurate linear screening helps maintain a narrow particle size distribution, improving granulation efficiency, and reducing unnecessary reprocessing.

Beyond the processing line, consistent sizing improves flowability in storage silos, reduces segregation during transport, and supports accurate filling during packaging or bulk loading. These downstream benefits illustrate how screening decisions made within the plant influence product performance throughout the supply chain.

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Read the article online at: https://www.worldfertilizer.com/special-reports/06022026/smart-screening-for-sustainable-fertilizers/