Structure-forming role and properties of phosphogypsum in unburned technology of wall materials and rare-earth metals concentrate simultaneous production

Abstract

The paper presents the theoretical aspects of the processes of structure formation of composites in the non-fired technology for producing building wall materials with the simultaneous extraction of a concentrate of non-radioactive rare-earth metals from phosphogypsum. The object of research is phosphogypsum – an environmentally-adverse chemical waste that accumulates in dumps over the years. The research results are illustrated with the X-ray fluorescence method, differential thermal calorimetry and spectrometry of the properties of phosphogypsum: radioactivity, chemical composition, dehydration energy, content of non-radioactive rare-earth metals. The effect of dehydration energy and pressure on the strength of the resulting building material is established. A flow chart of energy-saving non-firing technology for the direct production of wall materials with the simultaneous extraction of a rare-earth metal concentrate from phosphogypsum is presented. It has been shown that phosphogypsum can be used as a building material without radioactivity restrictions. It is proved that phosphogypsum exhibits astringent properties that provide annealing-free production of wall materials with the simultaneous extraction of a rare-earth metal concentrate. This technology allows for the selection of strategically important rare-earth metals from phosphogypsum while reducing the cost of production of wall materials by 2 - 3 times.