Kinetics of titanium leaching with citric acid in sulfuric acid from red mud

The recovery of titanium with citric acid in sulfuric acid from red mud was put forward to strengthen acid leaching efficiency. The main factors on the recovery of titanium such as citric acid addition, sulfuric acid concentration, leaching temperature, time and liquid-to-solid ratio were studied. The kinetics analysis of titanium leaching from red mud was deeply investigated. The results show that the citric acid could increase the recovery of titanium and decrease the consumption of sulfuric acid. The recovery of titanium was increased from 65% to 82% and the consumption of sulfuric acid was decreased by about 30% with using 5% citric acid. The dissolution of perovskite, brookite, and hematite in red mud could easily be dissolved using citric acid. The acid leaching process was controlled by internal diffusion of shrinking core model (SCM) and the correlation coefficient was above 0.98. The apparent rate constant was increased from 0.0012 to 0.0019 with 5% citric acid at 90 °C. The apparent activation energy of titanium leaching decreased from 39.77 kJ/mol to 34.61 kJ/mol with 5% citric acid.