PHOS4green – How the Phosphorus Recovery Works

Simple, flexible and stable process control due to separation of the process steps

In this process, the suspension production and thus the reaction of phosphate conversion between phosphate-containing secondary raw material and acid are separated from the granulation process. As a result, the raw material components are homogenized. For the conversion reaction, a suspension is produced from the phosphate-containing ash with the aid of an acid, in which the solid particles are distributed. The aim is to make the ash-based nutrients available to plants. Adapted to the available raw materials, the suspension is customized for the desired fertilizer product.

Depending on the application objective, water and other solid or liquid nutrient components, including additional phosphate sources, are added. The suspension step also makes it possible to better control and manage the tackiness of the system and the exothermic reaction. The high-energy reaction, which sometimes occurs spontaneously and violently when the phosphate-containing ashes and the acid are brought together directly, becomes controllable and manageable. The free acid is already largely converted in the suspension, effectively preventing corrosion of plant components.