Feasibility study of the new rutile extraction process from natural ilmenite ore based on the oxidation reaction
- PDF / 342,946 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 15 Downloads / 184 Views
INTRODUCTION
TITANIUM has many excellent characteristics such as light weight, high strength, heat resistance, corrosion resistance, nonmagnetic property, and biocompatibility, and metallic titanium is widely used for aircraft, chemical plant materials, medical equipment, eyeglass frames, golf clubs, and so forth. The metallic titanium is produced from highgrade rutile such as natural rutile, synthetic rutile, and titanium-rich slag by the Kroll process. Figure 1 shows the deposit and price of rutile and ilmenite ores in the world.[1] The price of rutile is 5 to 6 times higher than that of ilmenite, while the deposit of rutile is less than one-tenth of that of ilmenite. Thus, the available resources of high-grade natural rutile for a raw material in the extractive metallurgy of titanium tend to diminish, and the deposit of rutile is only about 50 million tons in the world. The titanium dioxide is generally used for pigments in large amounts, and also recently for photocatalysts and antibacterial materials in the environmental field. The oxide is commercially produced from natural ilmenite and rutile ores by sulfuric acid leaching, chlorination, and titanium-rich slag processes, and the amount of titanium dioxide pigment produced in the world reaches approximately 5 million tons per year.[1] However, they have problems such as high-energy consumption and a large amount of leaching residue. Therefore, the economic and environmentally friendly extraction processes of rutile from about 600 million tons ilmenite occurring in abundance worldwide[1] and supplying it to titanium and titanium dioxide industries are in great demand.
The compositions of natural ilmenite ores are plotted by the open circles in Figure 2, which is the phase diagram of the titanium-iron-oxygen ternary system at 1373 K.[2] The compositions of several natural ilmenite ores are present in the region of Fe2O3-FeTiO3-TiO2 system, which corresponds to a higher oxygen concentration range in the titanium-iron-oxygen ternary system, due to weathering. Webster and Bright[3] and Taylor[4] studied the FeOFe2O3-TiO2 system at 1473 and 1573 K, respectively. However, their data are unavailable for discussing eco processing at relative lower temperatures, because their reports dealt with higher temperatures. The objective of the present work is to investigate the phase relations and the equilibrium partial pressures of oxygen in the Fe2O3-FeTiO3-TiO2 system at 1373 K by quenching and electromotive force (EMF) methods, and also to develop a new extraction process of rutile from natural ilmenite ore based on oxidation reaction.
II.
EXPERIMENTAL
A. Experimental Principle of the Electromotive Force Method The oxygen partial pressure can be measured by an EMF method using the stabilized zirconia solid electrolyte. The cell is described as follows: ðÞ Pt, O2 ðIÞ=ZrO2 ð1CaOÞ=O2 ðIIÞ, Pt ð1Þ
[1]
The EMF of the cell is given as Eq. [2] under the experimental condition SATOSHI ITOH, Associate Professor, is with the Department of Environmental Studies, Graduate School
Data Loading...
