Dissolution of Iron from Oxides in Solutions of Citric Acid and Sodium Thiosulfate

摘要

In this work, the dissolution of iron from a kaolinitic mineral (Veracruz, Mexico) is compared with that from an iron ore (Michoacan, Mexico), a specular hematite (Mexico), a magnetite (southeastern Utah, USA) and a hematite (from Arizona, USA), using aqueous solutions of sodium thiosulfate and citric acid, as the reducing and complexing agents, respectively. The minerals were dry sieved to obtain particle sizes between -100 +250 mesh. The minerals were then characterized by X-ray diffraction (XRD), energy dispersive spectroscopy EDS and atomic absorption (AA). Leaching experiments employed 0.5 M of both reactants at a temperature of 363.15 °K and pH = 3; this last parameter was controlled with ammonium hydroxide. The experimental results showed an iron removal of greater than 99% in the kaolinitic clay and magnetite from Utah, but only 79% for the iron ore, 46.5% from the Arizona hematite and 30% from the Stone Plus hematite, in 180 minutes.