ilmenite

Iron and titanium oxide minerals

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Ilmenite is an oxide mineral of iron and titanium, also known as Titanomagnetite It is the main ore for extracting titanium. Ilmenite is very heavy, gray to black, with a little Metallic luster 。 The crystals are generally plate shaped, and the crystals are lumpy or granular together. Composed of FeTiO three 。 TiO two The content is 52.66%, which is used to extract titanium and titanium dioxide Main minerals 。 Tripartite system, in Panzhihua iron ore, Sichuan, China, ilmenite is distributed between magnetite particles or Cleavage And form large deposits. The chemical composition of ilmenite is related to the formation conditions. Ilmenite produced in ultrabasic rocks and basic rocks has high MgO content and basically no Nb and Ta; Alkaline rock Ilmenite with high MnO content and Nb, Ta Acid rock The content of FeO, MnO, Nb and Ta in ilmenite is relatively high.

Chinese name: ilmenite
Foreign name: Ilmenite
Also called: Titanomagnetite

Composition: One of the main titanium bearing minerals
Crystal system: Trigonal system
Application: Extraction of rare metal titanium

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one structure
two form
three type
four nature

seven research meaning
eight Industrial applications

structure

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English name

ilmenite

Ilmenite is one of the main titanium bearing minerals. Trilateral crystal system, rare crystal, often irregular granular Scaly , plate or sheet. colour Iron black Or steel grey, strip steel grey or black, when containing Hematite Inclusion It is brown or maroon. Metallic to semi metallic luster, shell like or sub metallic Conchoidal fracture 。 It is brittle. Hardness 5~6, density 4.4~5g/cm three The density increases with the decrease of MgO content or the increase of FeO content in the composition. It has weak magnetism. stay hydrofluoric acid Medium solubility is large, and it is slowly soluble in hot hydrochloric acid. Dissolve in phosphoric acid, cool and dilute, add Sodium peroxide or hydrogen peroxide The solution is yellowish brown or orange yellow. Ilmenite can be produced in various rock , on Basic rock and Acid rock It is widely distributed in the middle; Produced in Pegmatite The particle size is large, up to several centimeters. When ore bearing Parent rock After being destroyed by weathering, ilmenite can be transferred into placer ore.

ilmenite

The chemical composition of ilmenite is FeTiO three The crystal belongs to the oxide mineral of the trigonal system. The English name comes from the Ilmen Mountain (Илжменскиегоры) in Ural, Russia, where the mineral was originally found. Containing TiO two 52.66%, which is the most important for extracting titanium and titanium dioxide Main minerals Raw materials. The crystals are often plate shaped, and the aggregates are massive or granular. Steel grey to iron black, Streaks Black to maroon, Semi metallic luster 。 Mohs Hardness 5～6， proportion 4.70～4.78。 It has weak magnetism. Ilmenite is generally used as Accessory mineral See at igneous rock and Metamorphic rock Medium, can also form placer 。 Famous mines include Irmen Mountain in Russia, Craigler in Norway, Iron Mountain in Wyoming in the United States, and Ellard Lake in Quebec, Canada. Panzhihua iron ore deposit in Sichuan, China, is also a large ilmenite producing area. Its ilmenite is distributed in granular or flaky form magnetite Between particles or Cleavage Medium.^[1]

Theoretical composition of ilmenite: FeO 47.36%, TiO two 52.64% 。 Fe 2+ And Mg 2+ 、Mn 2+ Between can be complete Isomorphism Substitution, forming FeTiO three -MgTiO three Or FeTiO three -MnTiO three Series. It is called ilmenite when it is mainly FeO, and it is called MgO when it is mainly MgO Magnesite , when MnO is dominant Rhodochrosite 。 There are often isomorphic substitutions of Nb, Ta, etc. FeTiO three -Fe two O three Can form complete Solid solution 。 FeTiO three -Fe two O three The solid solution is exsolved and hematite is separated from ilmenite Lamella , and arrange them directionally according to (0001).

form

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Trigonal system ，arh=0.553nm，α=54°49'； Z=2。 Or ah=0.509nm, ch=1.407nm; Z=6. It can be regarded as corundum A derivative structure of a type structure. The difference is that Al in corundum 3+ The position of 2+ 、Ti 4+ It is replaced and arranged alternately, resulting in c Slip surface Disappear Space group Change from R3c to R3.

ilmenite

At high temperature, Fe and Ti in ilmenite are distributed disorderly Hematite Structure (i.e. corundum type structure), so FeTiO is formed three -Fe two O three Solid solution Its composition can be expressed as Fe three O two -xFe 2x Ti 4x O three (x stands for ilmenite mole fraction ）。 The temperature of space group from R3c to R3 is 1100 ℃ (x=0.65) to 600 ℃ (x=0.45). When 0.6>x ≥ 0.5, the completely ordered structure of space group R3 cannot be obtained; When x=0.5, R3c to R3 transforms into a metastable state, and the beginning of the solid solution Exsolution 。 Rhombohedron Crystalloid 。 It is often irregular granular, scaly or thick plate. Ilmenite and hematite are completely formed above 950 ℃ Isomorphism 。 When the temperature decreases, melting will occur, so ilmenite often contains fine scale hematite Inclusion 。 The color of ilmenite is iron black or steel gray. Strips are steel gray or black. The hematite inclusions are brown or brownish red streaks. Metallic - Semi metallic gloss. Opaque, None cleavage 。 The hardness is 5-6.5, and the specific gravity is 4-5. Weak magnetism. Ilmenite mainly occurs in Basic rock , basic rock Alkaline rock 、 Acid rock And metamorphic rocks. our country Panzhihua In vanadium titanium magnetite deposits, ilmenite is distributed in granular or flaky Titanomagnetite Between other mineral particles, or along the titanium magnetite fracture surface Lamellae 。^[2]

type

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ilmenite

Ilmenite, often used as accessory mineral, or dispersed in magnetite in strips and sheets in basic and ultrabasic rocks Enstatite , plagioclase, etc. Pegmatic ilmenite, occurring in granite pegmatite, and Microcline 、 Muscovite , quartz, magnetite, etc. Ilmenite is often found in Rich in alkaline rock Set. Because of its chemical property Stable, so it can form alluvial placer rutile 、 zircon 、 Monazite Symbiosis. according to Crystal form 、 Streaks Weak magnetism can be distinguished from hematite or magnetite. Ilmenite is the most important titanium ore mineral.

nature

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physical characteristics

Iron black or steel gray; Striped steel grey or black. Hematite bearing Inclusion It is brown or maroon. Metal to Semi metallic luster 。 Opaque. No cleavage. Sometimes appear or split. The hardness is 5~5.5. It is brittle. The relative density is 4.0~5.0. have Weak magnetism 。

Polarizer Bottom: Dark red, opaque or slightly transparent. Monoaxial crystal 。 With very high refractive index (N=2.7) and Refold rate 。

chemical properties

ilmenite

The ilmenite used in the experiment is a natural ore, reducing agent It is charcoal powder. The main phases in ore are CaO, MgO and SiO two 、Al two O three 、MnO two 、V two O five 、Cr two O three Etc. The composition of ore is 47.86% TiO two ，35.12%Fe，0.22%CaO，2.01%MgO，1.86%SiO two 。 The particle size of ore is less than 0.087mm, and that of charcoal powder is less than 0.076mm. Ore and Charcoal powder Dry at 105 ℃ for 24h, then mix and press into blocks in a certain proportion. Mixture The carbon content in is 20%. In the microwave carbothermal reduction process, the temperature of the material is gradually increased. It takes 3-8 min to heat the material from room temperature to 1123-1263K by microwave. The experiment shows that: Reduction reaction The microwave carbothermal reduction reaction of ilmenite started even at very low temperature. This characteristic of ilmenite is mainly that part of microwave energy will be localized Coupling resonance , generating hot spots. The temperature of these hot spots is much higher than that of other areas, so they will generate chemical reaction The center of the hot spot is the center of the reaction. In addition, atom Or molecules in Reaction center Intense vibration will also occur, which can better meet the conditions of chemical reaction, which will also reduce the temperature of chemical reaction. It is precisely because of the existence of these hot spots and the violent vibration of molecules or atoms that ilmenite Microwave carbothermal reduction reaction It can be carried out at a lower temperature, thus greatly reducing the energy consumption of the carbothermal reduction process of ilmenite.

The microwave reduction rate of ilmenite is closely related to the carbon content of the sample. When the initial carbon content of the sample is less than 20%, the reduction rate increases significantly with the increase of carbon content; When the carbon content is greater than 20%, further increase of carbon content has no obvious effect on the reduction rate.

Reaction formula: FeTiO three +C=Fe+TiO two +CO（1）FeTiO three +CO=Fe+TiO two +CO two （2）CO two +C=2CO（3） reaction rate When the carbon content is more than 20%, the reaction rate is independent of the carbon content. Microwave reduced rate Much faster than traditional restore. According to the information about microwave carbon for ilmenite Thermal reduction The comparison experiment with the traditional carbothermal reduction research shows that the microwave reduction rate of ilmenite is much faster than the traditional reduction rate. At 1153K, the microwave carbothermal reduction rate is 79.06 times of the traditional reduction rate. The rate of microwave reduction at 1153K can be compared with that of traditional reduction at 1422K, and the temperature difference between the two is as high as 269K, which also shows that when microwave heating is used instead of traditional heating, the carbothermal reduction of ilmenite can be carried out at a lower temperature.

Similar to the carbothermal reduction of iron ore, the carbothermal reduction of ilmenite is also strong Endothermic reaction （ΔH=+181kJ/molFeTiO three The "cold center" will also be generated when using traditional heating reduction. Since microwave can rapidly heat the whole material, the problem of "cold center" is naturally solved reaction rate Accelerated significantly.^[2]

Development history

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Titanium can also form many compounds, which also have various special properties and uses, such as titania , a white powder, is the best white pigment, commonly known as“ Titanium white ”One gram of titanium dioxide can paint an area of more than 450 square centimeters white. The titanium dioxide used as white pigment in the world is more than several hundred thousand tons a year. If titanium dioxide is added to the paper, it can make the paper white and opaque bank note Titanium dioxide is sometimes added to paper and art paper. In addition, titanium dioxide is sometimes added to lighten the color of plastics and soften the luster of rayon. Titanium dioxide is known as the whitest thing in the world. Most titanium in nature is in a dispersed state, mainly forming the mineral ilmenite TeTiO three and rutile TiO two , vanadium ilmenite, etc. Panzhihua, Sichuan, China is rich in vanadium ilmenite with reserves of about 1.5 billion tons.

So, how was titanium discovered? In 1791, English scientist Gregor found a kind of ore - black magnetic sand in the suburb of Minahan. Through the study of this ore, he believed that there was a new chemical element in the ore. And use the location where the ore was found“ Minahan ”Name this new element.

Four years later, the German chemist Klapulot discovered this new element from a red ore in Buynik, Hungary. He named it after the "Taidan" tribe in Greek mythology (in Chinese, it was named titanium according to the translation of its original name), Claplote He also specifically pointed out that the new element "Minahan" discovered by Grigor was titanium, but what was found at that time was actually powdery titanium dioxide rather than metallic titanium. Until 1910, the American chemist Han Del It is the first time to produce 99.9% pure titanium, but the total is less than 1 gram. It took 120 years from the discovery of titanium to the production of metallic titanium. In 1947, people began to smelt titanium in factories. At that time, the annual output was only 2 tons. By 1955, the output had soared to 20000 tons. By 1972, the annual output had reached 200000 tons. Titanium is used more and more widely, and people pay more and more attention to it. People call it the steel of the future, the metal of the 21st century.

Smelting method

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ilmenite

The smelting of ilmenite includes Sulfuric acid process Compared with the chlorination method, the two methods are only different in the treatment of titanium ore: the sulfuric acid method can use lower grade ferrotitanium ore, and can also produce ferrous sulfate The cost is low, but it is difficult to treat the by-products with too much pollution and consume too much sulfuric acid; Chlorination method Used Ore grade Higher and higher cost, but less pollution by-products and chlorine can be recycled. But both methods are to turn titanium ore into pure titanium dioxide, and then combine pure titanium dioxide with pure chlorine and coke Generated by reaction at high temperature Titanium tetrachloride and carbon monoxide , using Metallic calcium , magnesium or sodium to reduce it into spongy metallic titanium Mass production method of titanium:

Step 1: at high temperature, turn rutile (TiO two ）Mix with carbon powder (C) and feed chlorine Prepared TiCl four And a combustible gas CO.

Step 2: In the argon In the (Ar) environment, use excessive magnesium (Mg) to mix with TiCl under heating conditions four Reaction preparation Metallic titanium (Argon does not participate in the reaction).^[3]

research meaning

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Ilmenite distribution

Yunnan is the kingdom of nonferrous metals, and naturally attaches great importance to the development of nonferrous metals, Metallurgical technology With each passing day, efficiency is benefit. This research fills the gap of microwave reduction of ilmenite, and provides theoretical basis and method guidance for industrial use of microwave carbothermal reduction of ilmenite. Microwave carbothermal reduction of ilmenite can make reaction rate Speed up. Since microwave carbothermal reduction of ilmenite can be carried out at a lower temperature, the utilization of energy will be greatly reduced, which undoubtedly has great scientific and economic value for China, which is in short supply of energy. It is believed that this research will be applied to the industrial field and produce good economic and social benefits.

Industrial applications

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Pure titanium is a silver white metal. Titanium minerals are widely distributed in nature, accounting for about 0.6% of the weight of the crust, second only to aluminum, iron, calcium, sodium, potassium and magnesium, and several times or even dozens of times more than copper, tin, manganese, zinc, etc. in the crust. The melting point of titanium is 1725 ℃, which is characterized by low density and high strength. Compared with steel, its density is only 57% of that of steel, while its strength and hardness are similar to that of steel. Compared with aluminum, aluminum is less dense than titanium, but its mechanical strength is poor. Therefore, titanium has the advantages of both steel (high strength) and aluminum (light texture). Pure titanium has good plasticity, and its toughness exceeds pure iron 2 times, good heat resistance and corrosion resistance.

Because of these advantages, titanium has become an outstanding rare metal since the 1950s. Titanium and its alloys were first used in the manufacture of aircraft, rockets, missiles, warships, etc., and began to be popularized for the chemical and petroleum sectors. For example, in Supersonic aircraft In terms of manufacturing, due to the high surface temperature of such aircraft during high-speed flight, aluminum alloy or stainless steel has lost its original performance at this temperature, while titanium alloy still maintains good performance above 550 ℃ Mechanical properties Therefore, it can be used to manufacture high-speed aircraft that is three times faster than the sound speed. The amount of titanium used by this kind of aircraft accounts for 95% of the total weight of its structure, so it is called "titanium aircraft". More than half of the world's titanium is used to manufacture aircraft bodies and Jet engine Important parts. Titanium is used for manufacturing in the atomic energy industry nuclear reactor In the chemical industry, titanium is mainly used to manufacture various containers Reactor 、 heat exchanger , pipes, pumps and valves, etc. If titanium is added to stainless steel, only about 1% will greatly improve the rust resistance.^[3]

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