Phosphorus recovery into fertilizers and industrial products by ICL in Europe

Abstract

Phosphate recycling is an important issue, since phosphate is a finite resource which is essential to food security. The phosphate used in the fertilizer industry, which now solely comes from mining, has to be replaced with so-called secondary phosphates. At ICL Fertilizers, trials have been conducted to investigate the potential implementation of these sources of secondary phosphates into the fertilizer production. Extensive pilot-scale testing and several plant-scale tests have yielded promising results for the use of sewage sludge ash, meat and bone meal ash and struvite. The main issue remaining is the legislation for the use of these sources, as they are currently regarded as waste. Struvite is also suspected to be able to contain contaminants such as pathogens and pharmaceuticals, encapsulated in its crystals. Therefore, further research on this topic is necessary. In the draft of the new Fertilizer Regulations of the European Commission, maximum values for heavy metal content in fertilizer are discussed in greater detail. The first results show that products produced from sewage sludge ash (the big quantity of secondary phosphates) meet some of these demands; however some limits are put (without doing a risk assessment) too low and could block the use of these secondary phosphates in fertilizers. Since heavy metal content in struvite and meat and bone meal ash is low, no problems are expected. The use of secondary phosphate in fertilizer production yields great opportunities; however in parallel ICL is piloting other processes for production of industrial products (elemental phosphorous P 4 and food-grade phosphoric acid). The P 4 route is via the thermal RecoPhos process (inductive heating of ashes and evaporation, cleaning and condensation of the P 4 ) where no waste what so ever is created, only products with a positive market value. The food-grade phosphoric acid route is via the Tenova process, where ashes are treated with by-product HCl to produce phosphoric acid, which is then purified in several extraction stages. In the coming years, the pilot results will show the economic feasibility of these processes for which ICL has its own captive use in industrial applications. In this way ICL will try to turn the development of a circular economy from a threat into an opportunity.