WAPHCO Project: How to Produce High-Quality Merchant Grade Acid from El Wady Phosphate Rock Charged with Impurities?

Abstract

The WAPHCO Project consists of the construction of a phosphoric acid plant producing 500,000 metric tons of P2O5 per year as merchant grade acid (“MGA”) from the adjacent Abu Tartour phosphate ore mine in the southwestern desert of Egypt. The main issue with that ore is the high content of minor elements like iron, aluminum and magnesium. From a chemical standpoint, those elements lead to the formation of gels impeding negatively the production of phosphoric acid. During a preliminary bench scale test performed by Prayon, the acid could not be concentrated above 42% P2O5 while MGA specification requires at least 52%. At that stage, K-Technologies, Inc. (K-Tech) was introduced into the project to solve those “minor elements” issues. Indeed, the American company has developed and patented a technology to remove the minor element cations from a phos acid solution by continuous ion-exchange. Preliminary bench scale tests were performed successfully by K-Tech on phosphoric acid produced by Prayon from the Egyptian Rock. Consequently, WAPHCO decided to hire Prayon and K-Tech to design the plant based on a combined and integrated pilot plant test work program. Results of the pilot tests were even better than expected as the quality of the produced acid largely exceeded the usual requirement from fertilizer producers in terms of purity degree and post-precipitation characteristics. Moreover, performances of the Prayon Dihydrate Process regarding P2O5 recovery through attack and filtration were enhanced during pilot test phase. The final plant design elaborated after the tests is the consequence of close collaboration between Prayon and K-Tech. Synergies between processes will allow the client to save money on capital and operational costs of the plant, as well as produce a premium product for the marketplace.