Sheikh Abdul Rezan

Effect of Gas Atmosphere on Carbothermal Reduction and Nitridation of Titanium Dioxide

This article examined the reduction/nitridation of rutile in the He-N2, Ar-N2, and He (Ar)-H2-N2 gas mixtures, as well as pure nitrogen, in the temperature-programmed and isothermal experiments in a fixed-bed reactor. The extents of reduction and nitridation were determined from the off gas composition and LECO analysis. The off-gas composition was monitored using the infrared sensor (CO, CO2, and CH4) and dew point analyzer (H2O). The phase composition of the reduced samples was analyzed using X-ray diffraction (XRD). The temperature and gas composition had a strong effect on the rutile reduction. The reduction was the fastest in the H2-N2 gas mixture, followed by a reduction in nitrogen; the rate of reduction/nitridation in the He-N2 gas mixture was marginally higher than in the Ar-N2 gas. The rate of titania reduction/nitridation in the He (Ar)-H2-N2 gas increased with the replacement of He (Ar) with hydrogen. The article also discusses the mechanisms of reduction/nitridation in different gas atmospheres.

Phase development in carbothermal reduction and nitridation of ilmenite concentrates

Abstract The phase development in the course of carbothermal reduction and nitridation of ilmentie concentrates and synthetic rutile was studied in temperature programmed reduction (623–1873 K) and isothermal reduction experiments. Ilmenites and synthetic rutile were reduced in a tube reactor with continuously flowing hydrogen-nitrogen mixture or pure nitrogen. The rate and extent of reduction were monitored by online off-gas analysis. Samples reduced to different extent were subjected to XRD and SEM/BSE analyses. Pseudorutile and ilmenite were the main phases in ilmenite concentrates; rutile was the main phase in synthetic rutile. Pseudorutile was first converted to ilmenite and titania which occurred at temperatures below 623 K; iron oxides in ilmenite were quickly reduced to metallic iron. Titania was reduced to titanium suboxides and further to titanium oxycarbonitride. Reduction of ilmenites and synthetic rutile in hydrogen-nitrogen mixture was much faster than in pure nitrogen. The rate of conversion of titanium oxides to oxycarbonitride was affected by iron content in the ilmenites. The rate of reduction increased with increasing iron content in ilmenite (decreasing grade) when ilmenites were reduced in the hydrogen-nitrogen gas mixture, but decreased with decreasing ilmenite grade in reduction experiments in nitrogen; reduction in nitrogen was the fastest for synthetic rutile. The difference in the reduction behaviour was attributed to different chemical compositions and morphologies of ilmenites of different grades.

Microstructural Study of Reduced Malaysian Ilmenite by Carbothermal Reduction and Nitridation in Nitrogen Atmosphere

The reduction of Malaysia Ilmenite (FeTiO3) with coal by carbothermal reduction under N2 atmosphere was studied. Characterization of raw materials was done by XRD, XRF, Optical Microscopy (OM) and SEM analysis. Isothermal experiments were carried out using the pellets in a horizontal tube reactor with continuously flowing gas. From the experiments, 0-10 wt. % of FeCl3 was added in the ilmenite-coal mixtures before reduction. The mixture was reduced at 1100°C for 60, 120 and 180 minutes. The addition of FeCl3 acted as a catalyst and increased the rate of reduction. The microstructures of the reduced sample were porous with the addition of FeCl3. Furthermore, defects were observed due to increase release of Cl2 and CO during reduction. FeCl3 acted as catalyst in the gasification of coal by the Boudouard reaction. SEM analysis indicates that the microstructure of the particles was coarsened due to the addition of catalyst. Besides that, there was less agglomeration of metallic iron particles at higher addition of FeCl3. The effect of FeCl3 on the morphology iron was the nucleation of microscopic iron rich zones in the reduced sample. Keywords: Carbothermal Reduction, Iron Chloride, Malaysian Ilmenite, Nitridation, Titanium Oxycarbonitride.

Assessment of titanium carbide chlorination by statistical design

In present study, the effects of the process parameters on chlorination of Titanium Carbide (TiC) was studied. Besides that, process parameters were investigated by using experimental design of experiment (DOE) and statistical analysis. The chlorination of the samples was carried out at temperatures between 400 to 500°C. Effects of three parameters, namely temperature, soaking time, and molar ratio of potassium permanganate (KMnO4) to hydrochloric acid (HCl) were investigated. The interaction, on the rate of chlorination of TiC were statistically evaluated by using DOE. The weight loss (wt. %) was the main response taken into account in this paper. The results of the experimental design indicated that the main significant factor for chlorination of TiC was higher temperature, soaking time and higher molar ratio of KMnO4 to HCl. DOE results have demonstrated that the highest extent of chlorination obtained at the highest weight loss (wt. %) was about 54.59 wt. % at 500°C with a soaking time of 180 minutes and KMnO4 to HCl molar ratio of 0.17 respectively. The amounted to a titanium extraction of about 96.39 %. On the other hand, the lowest wt. lost was 30.76 wt. % and this was obtained at 500°C for 120 minutes with KMnO4 to HCl molar ratio of 0.09 respectively. The results obtained from this work will be employed as a guide for the future studies on chlorination of nitrided/carburized Malaysian ilmenite or titanium oxycarbonitride. The final aim was to produce TiCl4 at low temperatures (≤500°C) using the latter samples. The experimental values are in good agreement with calculations from the statistical model.

Microstructural Study of Leached Nitrided Malaysian Ilmenite with Coal-Polystyrene Reductant

Titanium oxycarbonitride (TiOxCyNz) produced from Malaysian ilmenite consists of impurities such as iron that adversely affect the efficiency of chlorination process. In this paper, the dissolution of iron present in TiOxCyNz was performed using ammonium chloride (NH4Cl) solution at 70 °C from 4-6 hrs. Effects of acid concentration, catalyst amount and leaching time on the rate of iron dissolution were also investigated. Microstructural and/or morphological studies of the raw materials, and products were carried out by X-ray diffraction (XRD), X-ray Fluorescence (XRF), scanning electron microscopy (SEM), and Energy Dispersive X-ray analysis. The results obtained from SEM/EDX analysis for the reduced samples HR15 (15% Polystyrene (PS) + 85% coal (C)), HR25 (25% PS + 75% C) and HR35 (35% PS + 65% C) showed that most of the Titanium oxycarbonitrides were found in the circular shape with increase grain coarsening. Iron dissolution was accelerated with acid concentrations and it increased with increasing leaching time from 4 to 6 hrs. The results also showed that the percentage of Fe removed from titanium oxycarbonitride was ~ 76.85% at 70 °C for 6 hrs with the PS/C ratio of 0.18 and 1 wt. % of glucose as catalyst.

An Assessment of the Carbothermal Reduction of Malaysian Ilmenite by Statistical Design

Statistical design analysis (factorial design) was utilized to verify the significance and the interaction between the studied factors include temperature, reduction time and catalyst amount. Carbothermal reduction of iron ore sample was carried out at temperature between 1000°C to 1200°C. The effects of operating parameters studied were extent of reduction (X), carbon consumed (Cconsumed ) and nitridation (XN). Temperature was the most influential parameter that showed strong interaction with the operating parameters, meanwhile, reduction time and catalyst have showed the contrary results and had a very low percentage of contribution. The results of the experimental design showed that the extent of reduction reached up to 93% at 1200°C using 10 wt. % catalysts after 180 minutes reduction. The use of 0-10 wt % catalyst at 1200°C for 180 min reduction significantly affect the X but did not for Cconsumed and XN.Keywords: Carbothermal Reduction, Factorial Design, Malaysian Ilmenite, Nitridation.

Extraction of titanium from low-iron nitrided Malaysian ilmenite by chlorination

In this paper, production of TiCl4 from low-iron nitrided ilmenite samples at relatively low temperature using chlorine gas generated from the reaction between KMnO4 and HCl has been investigated. The effects of chlorination soaking time, potassium permanganate (KMnO4) to hydrochloric acid (HCl) molar ratio and aluminium powder catalyst in chlorine gas generation on titanium extraction from nitrided Malaysian ilmenite were examined. The low-iron nitrided Malaysian ilmenite contained titanium oxycarbonitride (TiOxCyNz) after carbothermal reduction and nitridation with subsequent leaching. Chlorination process was performed at 500°C for 30 – 60 minutes. Statistical analysis of the data was done by Design of Experiment (DOE) to identify the significant variables and their interactions. The results achieved in this study showed that the highest extent of chlorination was about 98.34% at 500°C for 60 minutes. The lowest extent of chlorination was about 68.51% obtained in KMnO4 to HCl molar ratio of 2.0 and 0.3...

Kinetic modeling of liquefied petroleum gas (LPG) reduction of titania in MATLAB

In the present study, reduction of Titania (TiO2) by liquefied petroleum gas (LPG)-hydrogen-argon gas mixture was investigated by experimental and kinetic modelling in MATLAB. The reduction experiments were carried out in the temperature range of 1100-1200°C with a reduction time from 1-3 hours and 10-20 minutes of LPG flowing time. A shrinking core model (SCM) was employed for the kinetic modelling in order to determine the rate and extent of reduction. The highest experimental extent of reduction of 38% occurred at a temperature of 1200°C with 3 hours reduction time and 20 minutes of LPG flowing time. The SCM gave a predicted extent of reduction of 82.1% due to assumptions made in the model. The deviation between SCM and experimental data was attributed to porosity, thermodynamic properties and minute thermal fluctuations within the sample. In general, the reduction rates increased with increasing reduction temperature and LPG flowing time.

Minerals Characterization of Magnetic and Non-Magnetic Element from Black Sand Langkawi

Valuable minerals are defined as mineral which having good opportunities to economic and consireable important. The most commonly occurring sand mineral deposits are ilmenite, rutile, magnetite, cassiterite, monazite, tourmaline, zircon, kyanite, silimanite, and garnet. In Malaysia, mineral sand deposits is found in Langkawi which known as black sand Langkawi. Langkawi black sand having high amount of valuable minerals that is very crucial in the industrial and construction products. Characterizations of black sand acquire different techniques to concentrate and separate valuable minerals. These techniques utilize different in physical or chemical properties of the valuable and gangue (wastes) minerals. For magnetic is based on natural or induced differences in magnetic susceptibility or conductivity of the minerals.. They are used to distinguish and extract magnetic, slightly magnetic and non-magnetic components present in the heavy fraction (Rutile, Ilmenite, Magnetite, Garnets, Zircon and Monazite). All minerals will have one of three magnetic properties: ferromagnetic, paramagnetic and diamagnetic. Ferromagnetic minerals (i.e. Magnetite and Ilmenite) are magnetic and easily attracted to the poles of magnet. Paramagnetic and diamagnetic minerals in the group magnetic, but if the mixture of paramagnetic and diamagnetic minerals are passed through a magnetic field, the paramagnetic minerals will be pulled into the field and diamagnetic minerals separated from the field. By varying the intensity of the magnetic field, it is also possible to separate different paramagnetic minerals from each other. In this study, techniques used to separate valuable minerals from black sand are magnetic separator.

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.