Worldwide Novelty: FlashPhos process

This page concerns itself with the FlashPhos process, the difficulty of the sewage sludge exploitation as well as the fields of application and economic benefit of this process.

1. The problem with phosphate

In central Europe, especially in Switzerland, Germany, Austria, Luxemburg, Belgium and the Netherlands, as well as in several North American regions, China, Singapore, Malaysia and Japan the yield of sewage sludge in farming is getting more and more problematic and impossible. This is due to organic and inorganic problematic residues in the sewage sludge. 


The essential natural source of raw material “phosphate” (e.g apatite) is located in partially problematic regions and is currently running dry.

As a result, prices for elementary phosphorus, phosphorous acid, phosphoric acid, phosphorus derivates, food phosphates, fireproofing material, insecticides, herbicides and phosphate fertilizers are already rising.
Therefore the co-processing of phosphate containing residues (such as sewage sludge and meat-and-bone-meal) in the cement industry, municipal waste incinerators and conventional power plants is only for a very limited amount of time possible.

The periods of transitions end 2026/2028 in Germany and Switzerland.

Many F&E projects, partially funded by the EU, are trying to deal with the recovery of phosphorus/phosphates from municipal sewage sludge.

2. The problem with sewage sludge

Conventional methods for the recovery of phosphorus and phosphates are mainly based on wet chemical and thermochemical extraction concepts.

FlashPhos comparably shall be the most economic and the most straightforward process concept. Additionally there is a significant positive effect on the CO2 reduction, since the method is functioning residue-free. The remaining fractions can be used as active binder in the cement production. 

CO2 reduction and residue-free processing of sewage sludge

Concentrated heavy metals emerge as by-products. They are usable in the non-ferrous metallurgy. In contrast to conventional methods the highly problematic microfibers/nano particles in the sewage sludge are entirely destroyed during the high-temperature process.

A dioxine de nuovo synthesis, known from fluidized bed incineration, will be prevented with the FlashPhos method.

A dioxine de nuovo synthesis will be prevented with the FlashPhos method.

Therefore FlashPhos can be called a “zero waste” process. In addition to that the landfill volume can be saved and the exploitation of the cement raw material marl reduced. The utilisation of other phosphate carriers, such as steel mill slags and bypass-dusts, is of course possible and can contribute to an optimised melt formation.

The recovery of the nitrogen content of the sewage sludge is possible through adding the necessary lime carrier to the wet sewage sludge. Heating it up will yield ammonia.

3. The functioning of FlashPhos

The FlashPhos process is based on experiences and discoveries in the areas application of secondary fuel for the cement clinker production, the metallurgical RecoDust and Flashmelter processes and constitutes an independent progression of the EU funded RecoPhos method. 
(IPs AT411 363 and AT413283; www.recophos.com)



Especially organic containing dusts can be processed now without any risk of explosion. This is potentially very interesting for medium sized sewage treatment plants, meat-and-bone-meal producers, cement producers, lime industry, metallurgical processes, glass manufacturing companies, chemical industry, power plants and municipal waste incinerators.

Sewage sludge (around 75% dry substance), meat-and-bone-meal or a mixture of both is used as starting product gets compounded with oxygen in a special furnace constellation. This mixture is being put into a 1500° hot reactor. Depending of the mix ratio of sewage sludge and oxygen the “redox-potential” can be set up in der burning chamber.

The thermochemical reactions happen within a fraction of a second.

This circumstance naturally has a positive effect on CAPEX and the space requirement.

4. Business model FlashPhos and cement production

Currently cement industry uses large amounts of sewage sludge and meat-and-bone-meal as secondary fuel.

The generated heat is used for the clinker burning, however phosphorus is being lost during the process. In addition to that phosphorus is known to a harmful element in cement. Therefore the exergetic valuable heat loss of the FlashPhos method for the calcination of raw meal is being proposed.

The required infrastructure (authorisation, commissioning, silos, funding systems) is already available.
The pollutant free phosphate slag can also be put into a central “InduCarb” plant and transformed into ultra-pure elementary phosphorus, highly valuable hydraulic binders and a small amount of raw meal or cement. The waste gas energy can be used for preheating the inlet substance. 
(For further information, please check out patent EP 1841 699, 27.1.2005)

Big amounts of waste gas heat of clinker furnace can be used for the thermal drying of sewage sludge, providing another interesting synergy potential for the cement industry.

In Europe around 80.000 t.p.a of elementary phosphorus are being used in chemical industry. Since there are no phosphate ores and production facilities in Europe, elementary phosphorus is being imported from mainly Kazakhstan. This implies dependence on imports, as well as rising market prices.

In total the establishment of FlashPhos leads to an optimal zero waste process with comparably low investments and costs of production as well as a high synergy potential.

5. Economic considerations of FlashPhos

The costs of production for phosphate melting (in a cement plant) are estimated to be around 30-50€/t. (dry material sewage sludge 75% presumed). The market price for phosphate fertilizers lies around 250-300€/t.

Each year 280 mio t of raw phosphate (Apatite) are being exploited globally. The world market price for raw phosphate is currently around 80€/t. (2018)

Sources show increasing contamination (Uranium, Cadmium, rare earths)

Fluoride contents complicate reprocessing and the by-product slag can only be deposited. With the conventional wet chemical phosphorus extraction a big quantity of contaminated gypsum remains. Phosphate-gypsum hardly finds any application potential and therefore constitutes generally a strain for the environment.

The costs of production for elementary phosphorus with the FlashPhos process average 1200-1500€/t. The market price in contrast lies around 2500-3000€/t.

Annually around 80.000 jato P4 are being consumed in Europe.

As there is no phosphorus producer in Europe, P4 has to get imported from Kazakhstan and China. 


​The dangerous and expensive delivery line (5000 km) of the highly toxic and easily inflammable substance has to be support by water-sealed tank waggons.

6. Application examples: Filter dust Refinement

Essentially the FlashPhos reactor is capable of transforming industrial fine dusts into recyclable material.

Metallurgical filter dusts (steel mill dusts) for instance are converted into a marketable zinc fraction and into an iron girder for the cement/iron producing industry according to the RecoDust method.

2002 the first IP with DI Alfred Edlinger as inventor got accepted.
“Device and process to oxidise, reduce, calcinate, sinter or melt dusts”
(AT 411 363 and AT413 283)

These IPs also provide a fundamental base for the FlashPhos method.

7. Patent protection FlashPhos procedure

The FlashPhos concept was protected by 2 basic patents and international patent protection was successfully introduced. The patent holder is RadMat AG, Lucerne, Switzerland.

8. Innovation prizes