Red mud and phosphogypsum and their fields of application

This chapter describes the most recent findings for the utilization of red mud and phosphogypsum, especially for the construction industry. Red mud and phosphogypsum belong to the family of wastes produced in large quantities like blast furnace slag (BF slag), fly ash, or municipal waste incineration ash (MWA). Red mud is a residue obtained by the Bayer process during the manufacture of alumina. Phosphogypsum is a byproduct from the production of phosphoric acid by the wet process. In spite of many possible venues for utilization of these wastes, they are usually land filled or disposed of at sea. The first reason for this is that red mud and phosphogypsum are not considered toxic materials and the producers are under less pressure by environmental or governmental regulations. The second reason is that the characteristics of the red mud and phosphogypsum are not readily amenable for economical use in large-scale processes.Because of the large production of these byproducts, research must be done to find an economical use for these wastes.