The Influence of Phosphogypsum Microstructure on the Main Properties of Press-Formed Samples

The storage of the phosphogypsum in stockpiles causes serious environmental problems. In order to avoid them, this by-product should be utilised. Hence, one solution is to employ it as a binding material, so that its structural and binding properties must be satisfactory. Depending on the type of original phosphate rock, the microstructure of phosphogypsum may differ, determining its main physical-mechanical properties. However, research with comparative analyses of the properties of phosphogypsum from different origins is almost inexistent. Therefore, in this study, the microstructure of phosphogypsum from two different sources is analysed: the first type is from Kovdor mine (Russia); the second is a mixture between material from Kirov (Russia) and Casablanca (Morocco) mines. The microstructure of both phosphogypsum types was analysed and compared by applying SEM-DES analysis and by measuring the loss on ignition. In order to obtain high mechanical properties, the material was processed by press-forming. Eventually, the mechanical properties of hardened phosphogypsum of both types were obtained by compression test and then compared.