Mechanism of fluidized chlorination reaction of Kenya natural rutile ore

In this paper, the thermodynamics and kinetics of nature rutile carbochlorination in a fluidized-bed were investigated. The thermodynamic calculations of TiO₂–C–Cl₂ system show that when C is excess in the solid phase, titanium tetrachloride and carbon monoxide can exist stably. At high temperature, the reaction with CO as the product is the dominant reaction. The appropriate reaction conditions are as follows: reaction temperature of 950 °C, reaction time of 40 min, carbon ratio of 30 wt% of rutile, natural rutile particle size of −96 μm, petroleum coke size of −150 μm, and chlorine flow of 0.036 m³·h⁻¹. Under the above conditions, the reaction conversion rate of TiO₂ can reach about 95 %. This paper proposed a reaction rate model, and got a rutile chlorination rate formula, which is generally consistent with the experimental data. For the TiO₂–C–Cl₂ system, the reaction rate is dependent on the initial radius of rutile particle, density, and the partial pressures of Cl₂. From 900 to 1,000 °C, the apparent activation energy is 10.569 kJ·mol⁻¹, and the mass diffusion is found to be the main reaction-controlling step. The expression for the chlorine reaction rate in the C–Cl₂ system is obtained, and it depends on the degree of reaction, the partial pressure of Cl₂, and the size of rutile particle.