A Clean Process to Prepare High-Quality Acid-Soluble Titanium Slag from Titanium Middling Ore

Abstract

A direct reduction-magnetic separation-alkali leaching-dilute acid washing method was proposed to prepare high-quality acid-soluble titanium slag (HQASTS) from titanium middling ore. The relevant potential pH diagrams were built, and the analysis results showed that the pH values for alkali leaching and dilute acid washing should be higher than 13.50 and lower than 1.00, respectively. Increasing temperature was beneficial to alkali leaching but not to dilute acid washing. The effects of operating parameters on the TiO2 content and impurity oxides extraction ratios of titanium slag were investigated, and the optimal experimental conditions were obtained. The HQASTS was obtained with TiO2 and Fe2O3 content of 75.37 wt % and 0.96 wt %, respectively, under the above conditions. Furthermore, the leaching mechanism was studied by chemical analysis and X-ray diffraction (XRD) technology, and it was found that the alkali leaching-dilute acid washing process presented in this work could avoid the encapsulation of the unreacted anorthite by the calcium aluminum spinel generated in alkali leaching.

Research on High-Pressure Hydrochloric Acid Leaching of Scandium, Aluminum and Other Valuable Components from the Non-Magnetic Tailings Obtained from Red Mud after Iron Removal

“…The recovery degree of titanium for diluted acid is 18% at 50 • C; it decreases to less than 1% at temperatures above 100 • C. In contrast, the dissolution degree of titanium at 50 • C is 49% for concentrated acid; it increases to 77% with HPAL temperature rising up to 150 • C, then decreases to 36%. These results agree well with previously reported data [56,57], where perovskite is proved to be highly soluble in concentrated hydrochloric acid and poorly soluble in diluted acid. Hence, the use of high-pressure diluted hydrochloric acid leaching allows to separate selectively titanium and silicon from the other elements.…”

Research on High-Pressure Hydrochloric Acid Leaching of Scandium, Aluminium and Other Valuable Components from the Non-Magnetic Residues Obtained from Red Mud after Iron Removal

“…In contrast, the dissolution degree of titanium at 50 °C is 49% for concentrated acid; it increases to 77% with HPAL temperature rising up to 150 °C, then decreases to 36%. These results agree well with previously reported data [51,52], where perovskite is proved to be highly soluble in concentrated hydrochloric acid and poorly soluble in diluted acid. Hence, the use of high-pressure diluted hydrochloric acid leaching allows to separate selectively titanium and silicon from the other elements.…”

“…Therefore, the use of HPAL allows to avoid silica gel formation. The process can be described by the following equation [29,51]: M2SiO4(s) + 4HCl(l) + (4n-2)H2O(l) = 2MCl2 nH2O(l) + SiO2(filterable),…”

One-Step Synthesis of Iron and Titanium-Based Compounds Using Black Mineral Sands and Oxalic Acid under Subcritical Water Conditions

“…Based on the abovementioned facts, it can be inferred that the dissolution of the ferrotitaniferous black sand was favored as the proton concentration in the reaction medium increased. In addition, Pourbaix diagrams for Fe-H 2 O [50] and FeTiO 3 -H 2 O [15] systems also report that up to pH 4 (high proton concentration), the soluble iron Fe +2 is the predominant species, while titanium still remains as the insoluble oxide TiO 2 (s) [15]. To discuss further the influence of oxalic acid concentration on the synthesis reaction, the oxalic acid dissociation constants (Ka 1 and Ka 2 ), pH, and ionic strength were considered (Table 2).…”

“…This stage is even more important if we consider that some of these ferrotitaniferous black sands are naturally occurring ilmenitehematite solid solutions (IH SSs), which are more difficult to dissolve, in comparison with the ones composed only of ilmenite [13]. For this reason, efforts have been devoted to the improvement of the throughput of the dissolution stage [14], and to the development of cleaner processing that minimizes the usage of toxic chemicals [4,15]. Organic acids, for example, represent an effective alternative to strong mineral acids in acid leaching.…”