The Leaching Kinetics of Iron from Titanium Gypsum in a Citric Acid Medium and Obtain Materials by Leaching Liquid

Abstract

In this study, the effect of citric acid on iron leaching from titanium gypsum (TiG) was systematically investigated. The conditions for the leaching of valuable metals were optimized while varying such parameters as the leaching time, citric acid mass fraction, leaching temperature, and the liquid–solid ratio. It was found that under the conditions of a citric acid mass fraction of 10%, at a 80 °C leaching temperature, a leaching duration of 80–90 min and a liquid–solid ratio of 8, the whiteness of titanium gypsum (TiG) increased from 8.1 to 36.5, and the leaching efficiencies of iron reached 84.37%. The kinetic analysis indicated that the leaching process of iron from TiG was controlled by the reaction product layer from 0–20 min, while the leaching process of iron from TiG was controlled by internal diffusion from 20–90 min. The apparent activation energy of the leaching reactions was 33.91 kJ/mol and 16.59 kJ/mol, respectively. High-value-added calcium oxalate and ferrous oxalate were prepared from the calcium and iron in the filtrate of the oxalic acid extraction. The leaching liquid could be recycled, which will provide a new way to utilize titanium gypsum.

Application of the Industrial Byproduct Gypsum in Building Materials: A Review

“…The displaced [SiO 4 ] can react with free Ca 2+ to form a new gel, and the presence of [SiO 4 ] will also increase the solubility of the active Al. Moreover, the synergistic effect of the three solid wastes results in curing Na + , and calcite has the ability to absorb and encapsulate Na + [34]. The positive valence state of sodium ions can be balanced by the charge of alumina tetrahedra with a negative valence, and chemical bonds are formed between sodium and aluminum atoms to achieve stable curing of sodium ions [31].…”