Ilmenite is one of the main titanium-bearing minerals. […]
Ilmenite is one of the main titanium-bearing minerals. Trigonal system, crystals are rare, often irregular grains, scales, plates or flakes. The color is iron black or steel gray, streak steel gray or black, when containing hematite inclusions, it is brown or maroon. Metal to semi-metallic luster, shell-shaped or subshell-shaped fractures. Brittle. The hardness is 5-6, and the density is 4.4-5 g / cm3. The density increases as the MgO content in the composition decreases or the FeO content increases. With weak magnetism. It is more soluble in hydrofluoric acid and slowly dissolves in hot hydrochloric acid. After dissolving in phosphoric acid and cooling and diluting, sodium peroxide or hydrogen peroxide is added, and the solution is yellowish brown or orange yellow. Ilmenite can be produced in various rock masses, and is widely distributed in basic rocks and acid rocks; those produced in pegmatite have a larger particle size, up to a few centimeters. When the ore-bearing mother rock is destroyed by weathering, ilmenite can be transferred to sand ore.
The chemical composition of ilmenite is FeTiO3, and the crystal belongs to the trigonal oxide mineral. The English name comes from the Ilmen Mountain (Ильменские горы) in Ural, Russia, where the mineral was originally discovered. Containing TiO252.66%, it is the most important mineral raw material for extracting titanium and titanium dioxide. The crystals are often plate-shaped, and the aggregates are massive or granular. Steel gray to iron black, streaks black to maroon, semi-metallic luster. Moss hardness is 5 ～ 6, specific gravity is 4.70 ～ 4.78. With weak magnetism. Ilmenite is generally found as an accessory mineral in igneous rocks and metamorphic rocks, and can also form sand deposits. Famous mines include Mount Ilmen in Russia, Krager in Norway and Iron Mountain in Wyoming in the United States, and Lake Erad in Quebec, Canada. Panzhihua iron ore in Sichuan, China is also a large ilmenite ore producing area, and its ilmenite is distributed in the form of fine particles or flakes between magnetite particles or in fissures. 
The theoretical composition of ilmenite: FeO 47.36%, TiO2 52.64%. Fe2 + and Mg2 + and Mn2 + can be replaced by completely quasi-homogeneous, forming FeTiO3-MgTiO3 or FeTiO3-MnTiO3 series. When mainly FeO is called ilmenite, when MgO is mainly called magnesite, and when MnO is mainly called red titanium manganese. There are often similar qualitative alternatives such as Nb and Ta. Under high temperature condition> 960 ℃, FeTiO3-Fe2O3 can form complete solid solution. As the temperature drops, at about 600 ° C, the solid solution of FeTiO3-Fe2O3 dissolves, and the platelets of hematite are precipitated in ilmenite, and they are aligned according to (0001) orientation.