Radiological Impact of the Application of Phosphogypsum in Civil Construction: an Overview of Brazilian Studies

In the last decades considerable attention has been given to naturally occurring radioactive material (NORM). Within this frame, of particular concern is the phosphate fertilizer industry. In Brazil, four main industries (Ultrafertil, Copebrás, Fosfertil and Bunge Fertilizantes) are responsible for the production of 1.2x10 6 tons per year of P2O5. Phosphogypsum is the by-product of the phosphoric acid industry, obtained by reacting phosphate rock with sulphuric acid. This waste is stockpiled in the surrounding environment of the facilities at a rate of 5.5x10 6 tons per year. The level of radioactivity present in the phosphogypsum, among other impurities, prevents its reuse for a variety of purposes. All the countries that produce phosphate fertilizer by acid wet processing of phosphate rock are facing the same problem of finding solutions for the safe application of phosphogypsum, in order to minimize the impact caused by its disposal. This paper aims to present a review of the research carried out at Instituto de Pesquisas Energéticas e Nucleares (IPEN), São Paulo, Brazil, focusing in the radiological implications of using Brazilian phosphogypsum as building material: bricks and plaster. The results and conclusions achieved can contribute to the development of national standards and guidelines concerning the safe use and management of phosphogypsum as a building material.