Extraction of valuable metals from acidic wastewater and blast furnace slag by a collaborative utilization process

Abstract

Two typical wastes, acidic wastewater and titanium‐bearing blast furnace slag, are generated in the smelting process of vanadium‐titanium magnetite. Generally, the acidic wastewater is neutralized by lime or limestone and titanium‐bearing blast furnace slag is directly stacked in the tailings pond, which not only pollutes the ecological environment but also causes the waste of metal resources. In this study, a collaborative utilization process for efficient extraction of titanium, iron, magnesium, and aluminum from acidic wastewater and low titanium‐bearing blast furnace (LTBBF) slag was proposed. At the leaching temperature of 80°C, the leaching time of 50 min, and the liquid–solid ratio of 9:1, 99.26% Ti, 99.47% Mg, and 99.45% Al could be extracted from LTBBF slag by acidic wastewater. Leaching residue mainly composed of Ca and Si could be used as silicon fertilizer. The Ti in the leaching solution could be separated by adding Na3PO4. The precipitation efficiency of Ti reached 98.53% under the molar ratio of Na3PO4 to TiO2 of 1.4, reaction temperature of 85°C, and reaction time of 40 min. The titanium phosphate ((TiO)2P2O7) was obtained by calcination of the precipitate at 900°C for 3 h. Adding oxalic acid to the filtrate above, the precipitation efficiency of Fe, Mg, and Mn reached 96.47%, 99.21%, and 99.45%, respectively, under the optimal conditions, while the precipitation efficiency of Al was only .38%. By adjusting the pH of the filtrate to 6.5, 99.83% Al could be precipitated as Al(OH)3, and the final solution was evaporated to obtain Na2SO4 products. The method proposed realizes the harmless treatment of acidic wastewater and LTBBF slag and recovers the metal resources in both of them.

A Novel Approach for Comprehensive Utilization by Leaching Pyrite Cinder with Titanium Dioxide Waste Acid by Response Surface Methodology

“…Approximately 3.364 million tons of titanium dioxide pigments were produced by using the sulfate process in China in 2022, resulting in about 27 million tons of 20% waste sulfuric acid, which would cause great harm to the environment. In recent years, a series of studies had been conducted on valuable metal extraction, harmless resource utilization, recovery of titanium and sulfuric acid, and pressure leaching of titanium concentrate, − providing useful references for the comprehensive utilization of TiO 2 pigment waste acid.…”