Ilmenite is an oxide mineral of iron and titanium, and is the main ore for titanium extraction. Ilmenite is heavy, gray to black, with a little metallic luster. The crystals are generally plate-shaped, and the crystals are aggregated into a massive or granular shape. The composition is FeTiO3. Containing TiO252.66%, it is the main mineral for extracting titanium and titanium dioxide. In the trigonal system, Panzhihua iron ore in Sichuan, China, ilmenite is distributed between magnetite particles or in fissures and forms large deposits. The chemical composition of ilmenite is related to the formation conditions. The ilmenite produced in ultrabasic rocks and basic rocks has a high MgO content and is basically free of Nb and Ta; the ilmenite in alkaline rocks has a high MnO content and contains Nb and Ta The ilmenite in acid rock has high FeO and MnO contents, and relatively high Nb and Ta contents.
Smelting of ilmenite includes sulfuric acid method and chlorination method, the two methods are only different in the treatment of titanium ore:
The sulfuric acid method can use lower-grade ilmenite ore, and it can also produce ferrous sulfate at a low cost, but the pollution is too large and the by-products are difficult to handle and consume more sulfuric acid; the ore used by the chlorination method has a higher grade and higher cost, but There are fewer by-products of pollution and chlorine can be recycled. But both methods turn titanium ore into pure titanium dioxide, then react the pure titanium dioxide with pure chlorine and coke at high temperature to produce titanium tetrachloride and carbon monoxide, and finally reduce it to a sponge shape with metal calcium, magnesium or sodium Titanium
Current method for mass production of titanium:
First step: at high temperature, mix rutile (TiO2) and carbon powder (C), and pass chlorine gas to produce TiCl4 and a combustible gas CO.
The second step: in the argon (Ar) environment, using excessive magnesium (Mg) under heating conditions to react with TiCl4 to produce metal titanium (argon does not participate in the reaction)
Industrial applications
Pure titanium is a silver-white metal. Titanium minerals are widely distributed in nature, accounting for about 0.6% of the earth’s crust, second only to aluminum, iron, calcium, sodium, potassium, and magnesium, but more than copper, tin, manganese, and zinc in the earth’s crust. Several times or even dozens of times. The melting point of titanium is 1725 ° C. Its main feature is its low density and high strength. Compared with steel, its density is only equivalent to 57% of steel, and its strength and hardness are similar to steel. Compared with aluminum, aluminum has a lower density than titanium, but its mechanical strength is poor. Therefore, titanium has both the advantages of steel (high strength) and aluminum (light texture). Pure titanium has good plasticity, its toughness is more than twice that of pure iron, and its heat resistance and corrosion resistance are also very good.
Because titanium has these advantages, it has become a prominent rare metal since the 1950s. Titanium and its alloys, first used in the manufacture of aircraft, rockets, missiles, ships, etc., are currently being promoted to the chemical and petroleum sectors. For example, in the manufacture of supersonic aircraft, due to the high surface temperature of these aircraft during high-speed flight, aluminum alloy or stainless steel is used. At this temperature, the original performance has been lost and the titanium alloy remains good above 550 ℃ The mechanical properties can be used to manufacture high-speed aircraft that exceed 3 times the speed of sound. The amount of titanium used in this aircraft accounts for 95% of the total weight of its structure, so it is known as “titanium aircraft”. Currently, more than half of the world’s titanium is used to manufacture aircraft fuselages and jet engines Important parts. In the atomic energy industry, titanium is used to manufacture the main parts of nuclear reactors. In the chemical industry, titanium is mainly used to manufacture various vessels, reactors, heat exchangers, pipes, pumps, and valves. If titanium is added to stainless steel, only about one percent is added, which greatly improves the ability to resist rust.
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