Process & contact
AshDec (Metso Outotec)
Member of ESPP
All ashes with P-content >7%
Modified Rhenania Phosphate (Calcium-Sodium-Phosphate) Pnac solubility >80%; granular material with P2O5 content of 15-25% (depending on input-ash); no organic matter; product is blendable with all other fertilising products.
Ash is mixed with a sodium carrier (Na2CO3 or NaHCO3) and heated to about 850-900°C in a rotary kiln to modify the P-compounds to neutral-ammonium-citrate soluble CaNaPO4 (Rhenania Phosphate). Heavy metals are partly removed and captured in a baghouse filter from where they can be separated from the fertilising product as a small waste stream (3-5% of input material). Hence, > 97 % of phosphorus and other elements in input ash are recovered.
Recovery rate (P in final product / P in input ash): >95 %
Recovery rate (% from input ash in recycle stream) of iron, aluminium: >95%.
Removal of heavy metals (% from input ash in final phosphate product): Cd: ~ 50 % removal, Pb: ~10 %, As: ~ 50 %.
Cu, Zn and Ni are not removed from the ash with the standard process. Removal of Cu and Zn can be enhanced by use of chlorine additives.
Pilot plant (300 kg/h, photo) operational for several years, Leoben, Austria. Continuous operating campaigns produced several hundred tons of product.
A full scale plant (30 000 t/y ash input) is planned in Altenstadt (Bavaria), with Enter GmbH and sePura GmbH, in the R-Rhenalia RePhoR project.