Title:
Enhancement and Modification of Raw Fluorogypsum with CaO and NaHCO3
Author(s):
Hang He, Yuli Wang, Junjie Wang, Huiyu Tang, and Rong Huang
Publication:
Materials Journal
Volume:
123
Issue:
4
Appears on pages(s):
19-32
Keywords:
modification; NaHCO3; raw fluorogypsum; solid wastes; soluble fluorides
DOI:
10.14359/51750610
Date:
7/1/2026
Abstract:
Raw fluorogypsum usually contains a high amount of soluble fluoride ions, which can cause serious environmental pollution. Investigations on the solidifying soluble fluoride ions and modification of raw fluorogypsum with CaO and NaHCO3 were carried out. The findings indicate that CaO contributed to an increase in pH and grindability of raw fluorogypsum, and a significant reduction of 80.7% in soluble fluoride ions was observed in fluorogypsum with 0.75 wt. % CaO. NaHCO3 significantly enhanced the hydration activity of fluorogypsum by increasing the solubility of fluorogypsum, leading to increased supersaturation and inhibition of dihydrate gypsum dissolution. An impressive increase of more than 500% in 3-day compressive strength in fluorogypsum with 0.75 wt. % CaO and 1.0 wt. % NaHCO3 was achieved. The reaction between NaHCO3 and fluorogypsum resulted in the formation of calcium carbonate and sodium bisulfate, and the latter acted as a catalyst for accelerating the hydration process of fluorogypsum. Furthermore, NaHCO3 changed the morphology of hydrated dihydrate gypsum from plate-like to short columnar shape and optimized the pore structure of hardened fluorogypsum paste.
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