Fertilizer Granule Formation with Recovered Phosphorus by PHOS4green
Transfer of the finished suspension directly into a dry, dust-free granulate with defined properties
Using continuous spray granulation to produce phosphate-containing fertilizer
Spray granulation in the fluid bed refines the digested phosphate into a marketable product. This enables you to produce round pellets with a compact, homogeneous particle structure. The process allows the drying of liquids – like suspensions from sewage sludge ash – to produce dust-free, flowable, easy-to-dose granules with high bulk density and a narrow particle size distribution.
Fluidized bed processes are used for thermal treatment and drying to form granules from powders or liquids and to coat particles. A fluidized bed is formed when process air lifts and fluidizes a layer of solid particles. The process air simultaneously provides the thermal energy required for particle production. The process time varies depending on the raw materials and the end product, for example, if substances in the formulation tend to stick together. Once the target size of the fertilizer granules is reached, the product is discharged. It is immediately ready for use and can be directly packaged, shipped and dosed.
The phosphate suspension is sprayed into the fluidized bed in the process chamber and dries on to the particles already in the bed, initiating layer-by-layer particle growth. The small solid particles required to maintain the granular structure are generated in the process itself. These serve as carrier nuclei for the formation of new fertilizer granules. The liquid raw material suspension is the only required raw material.
Principle of spray granulation in the fluidized bed: solid particles from the suspension are wetted with spray liquid, which evaporates and forms a solid shell consisting of several layers.
Exceptional fertilizer quality due to the sophistication of granulation
The granules produced have a dense surface with high abrasion resistance. This brings improved product properties and reduced occurrence of undesirable drift phenomena when spreading the fertilizers. In addition, the solubility of such granules can be very well adapted to soil-, plant- and weather-specific application conditions. Parameters such as particle size, residual moisture and solids content can be specifically influenced to achieve different product properties.
Here are some examples of different phosphate fertilizers and phosphate-containing multi-nutrient fertilizers:
Optional: Further options for functionalization with subsequent fluidized bed coating.
If required, the particles can be coated with a functional protective layer. Such a coating protects active substances, for example, from storage, transport or application-related influences, masks unwanted odor and enables colored branding as well as the targeted release of active ingredients.
The application of the coating material by spraying the solids-containing liquid onto the fluidized particles, as well as the drying and solidification of the film, take place in one process step.
Glatt uses its many years of experience in the production of special fertilizers to meet customer requirements, e.g.:
- long-term fertilization
- multi-component fertilization
- functionalities such as controlled release or slow release through defined coating of the fertilizer granules
The application of various coating materials with the aid of fluid bed coating makes it possible to fulfill such functions.
The coating/enveloping of the fertilizer granules is carried out in compliance with the currently valid regulations of the Fertilizer Ordinance – German Düngemittelverordnung (DüMV) and Regulation EG No. 2019/1009. Conformity to some of these requirements is often only achieved through the use of auxiliary materials.
Examples of coating materials that are used in the process of fertilizer coating in the fluid bed include:
- hydrophobic materials
- nitrification inhibitors
- urease inhibitors
- polymers, sulfur-coated
Here are some examples of fertilizer granules that have been coated: