Secondary Phosphorus as Raw Material for the Chemical Industry
The element phosphorus (P) occurs naturally in the form of phosphates and is an essential nutrient for all organisms. Thus, it is of crucial importance for food production. Agricultural areas were previ-ously fertilized with manure. Increased demands on the productivity of agricultural operations soon made the use of mineral phosphorus sources necessary. Phosphorus can be found in Phosphate ore deposits which are distributed very unevenly around the world.
90 % of produced phosphorous are used in the fertilizer industry where mined phosphate ore is first processed into phosphate rock. Phosphate rock can then be processed into various fertilizers.
Approx. 10 % of the phosphorus extracted is used in industrial applications where either technical phosphoric acid or white phosphorus - both made from phosphate rock - are used. Since phospho-rus is involved in countless production processes, analog to biology, phosphorus can also be viewed as a technical nutrient analog.
So far, hardly any mineral phosphorus deposits have been found in the EU. Coupled with an in-creasing demand for phosphorus in the future, certain supply risks are bound to arise. For this rea-son, both phosphate rock and white phosphorus are included on the EU's list of critical raw materi-als.
The use of phosphorus is largely linear. In order to reduce the dependency on imports, however, effective raw material recycling is needed.
Municipal sewage sludge has been identified as the waste stream that is generally the largest sink for secondary phosphorus. Relevant projects have been dealing with the recovery of phosphorus from this anthropogenic source for years. Sewage sludge mono-incineration with subsequent phosphorus recovery from the ash is currently seen as the most promising approach in this regard. Not only is phosphorus recovered by this approach but pollutants and contaminants are also relia-bly removed in the course of the incineration process. However, effective raw material recycling not only requires the availability of recovery technologies, but also the creation of value chains.
In the past, secondary phosphorus was mainly used in the fertilizer industry. Nowadays, technical possibilities for further areas of application are already available & feasible.
This paper investigates the potential of secondary phosphorus use in domestic industry applica-tions. For this purpose, a literature research was carried out and experts and stakeholders were interviewed. Although technical phosphates are processed by local industry, the quantities and achievable product prices are (currently) too low to make commitments outside of applications in the fertilizer industry.
In the European context, the implementation of an innovative value chain based on secondary phosphorus has great potential. White phosphorus is of particular importance, as the EU no longer has its own local industries. Further innovations in the field of phosphorus recycling are expected in the future.