Kinetic Modeling of Ilmenite Reduction with Compressed Natural Gas (CNG) Using MATLAB

The reduction of ilmenite by a gas comprising of CNG, hydrogen and nitrogen mixture was investigated by experimental and kinetic modeling in MATLAB. The CNG flow time was varied from 15 to 45 minutes at the temperatures of 1100-1200°C for 1-3 hours. In order to predict the extent of reduction, a shrinking core model (SCM) and crackling core model (CCM) were employed for the kinetic modeling. The results showed that the extent of reduction of 80% was achieved by using a CNG flow time of 45 minutes at 1200°C for 1 hour. The kinetic modeling for non-isothermal SCM at the same conditions gave a predicted value of 87%. The CCM gave a predicted value of about 100% at the same conditions. The non-isothermal SCM showed a closer trend to the experimental results. The deviation between SCM and CCM with the experimental data was attributed to porosity, thermodynamic properties and minute thermal fluctuations within the sample during the reduction process.

Reduction of Ilmenite in the Presence of Sulfur

Synthetic rutile has been produced from a Western Australian ilmenite by reducing it under controlled oxygen and sulfur fugacities , then leaching out the resulting metallic and sulfide phases with a bromine-in-methanol solution. The grade of the synthetic rutile has been determined as a function of reduction temperature, reduction time and oxygen fugacity. Experimental limitations precluded investigation of different sulfur fugacities. Reductions performed at 1301, 1348 and 1423 K have shown that synthetic rutile produced at 1301and 1348 K has a higher grade than that produced at 1423 K. In addition, the reduction time required to achieve a high-grade product at 1301 and 1348 K has been found to be less than that required at 1423 K. Included in the paper are an indication of how phase equilibria for the Fe- Mn -Ti-O-S system can be used to predict the grades of synthetic rutile produced at other temperatures or sulfur fugacities, and a discussion of how the reported results can be applied to ilmenite reduction in coal-fired kilns.