Process & contact
Spodofos (ThermusP)
Updated 9/2024
Input materials
Ashes from sewage sludge and bone meal incineration, vivianite, struvite and biochar.
Output products
- White phosphorus (P4), mean efficiency >90%
- High aluminia slag, successfully tested in refractory materials and ceme
nt - Ferrophosphorus (<10%P), direct use in sink-float processes; convertible to FeCl3 coagulant
- Volatiles (lead, zinc, alkalis) to recycle or disposal (not tested yet).
Process description
Secondary aluminium (preferably recovered from bottom ash of municipal waste incineration) and a phosphate containing ash are mixed and preheated, resulting in a reactive mixture. After ignition in the reactor, a solid-solid, highly exothermic thermite reaction occurs, raising the temperature to >1700°C where the phosphate and the iron oxides are reduced. Phosphorus gas distills off and is condensated. The liquid metallic iron and mineral (slag) are drained, separated by density and solidified.
Unlike in conventional phosphorus furnaces (using cokes, electricity and gravel), pre-sintering of the input materials is not necessary, electrical power for the reaction is omitted and carbon monoxide is not generated.
External energy is only needed for limited preheating of the input materials. In Spodofos, the aluminium acts as a reducing agent and as an energy carrier. The CO2 footprint of all products is extremely low (LCA report available). Normal iron contents in sewage sludge ash can be used in the process. Heavy metals are immobilized or collected as a rest stream.
Spodofos is characterized by few and compact processing steps.
Operating status
TRL5 achieved; prototypes for pilot (TRL6) ready. Product application tests have been performed.
STOWA report on Spodofos 5/1/2022 “Spodofos: witte-fosforproductie uit slibverbrandingsassen. Eerste evaluatie van de duurzaamheid en technologische en economische haalbaarheid”