h i g h l i g h t s Phosphate washing waste is one of phosphate sub product. The calcined phosphate washing waste was used as geopolymer precursors. The performance and the formed phases after alkali activation depend with calcination temperature.
Phosphate washing waste (PWW) is one of the wastes generated by the phosphate mine with a very high amount. This waste was investigated in this work to study the effect of the calcination of the PWW at four different temperatures 600°C, 700°C, 800°C and 900°C on its mineralogical and chemical composition. The samples were investigated by X-ray powder diffraction, Fourier transform infrared, differential scanning calorimetry and thermogravimetric analysis, solidstate magic angle spinning nuclear magnetic resonance of 29 Si, 27 Al and 31 P and scanning electron microscope. The results show that the PWW presents a complex system and it suffers a significant change on its mineralogical and chemical composition after calcination. It reveals the presence of carbonate, natural zeolite, fluorapatite, quartz and clay. After calcination, the waste shows the disappearance of some of these phases and the appearance of others and some other phases remain steady.
The extraction of the phosphate ore produces a high amount of waste causing serious environmental problems. This waste, termed as phosphate washing waste, was filtered and dried at 105°C for 24 h to remove the water. The dried waste was milled and then sieved in a 100 µm sieve. The resulting phosphates washing waste (PWW) particles size are below 70 µm. The phosphate washing waste was calcined at 700°C and 900°C.n Both calcined and uncalcined waste were investigated with X-ray fluorescence (XRF), Xray powder diffraction (DRX), Fourier transform infrared (FTIR), simultaneous differential thermal and thermogravimetric analyses (DTA-TG) and particle size analysis. This waste was activated with sodium hydroxide (NaOH) and sodium silicate in order to produce geopolymeric materials. The influence of replacing PWW by 15% of metakaolin was also study. The results show that the highest compressive strength is obtained with metakaolin. The results also showed that compressive strength decreased with the increase of NaOH concentration.
The valorization of phosphate mine waste (PMW) in different fields has recently become attractive to many researchers. This review paper examines the potential use of PMW as a raw material in different applications toward sustainable management strategies. Dewatering, recovery of phosphate and heavy metals, building materials and ceramics applications have been captured in this paper. Based on the origin of deposit and the treatment during ore beneficiation, the PMW shows different mineral compositions and various percentage of chemical elements which make it suitable for most of the studied applications. The objective of this paper is to show the potential of the phosphate mine waste valorization and to identify the knowledge gap.
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