Introduction and details of ilmenite

Structure

English name

ilmenite

Ilmenite is one of the main titanium-bearing minerals. Tetragonal crystal system, crystals are rare, often irregular grains, scales, plates or flakes. The color is iron black or steel gray, streaks of steel gray or black, when containing hematite inclusions, brown or maroon. Metallic to semi-metallic luster, shell-like or sub-shell-like fracture. Brittle. Hardness 5~6, density 4.4~5g/cm 3, density increases as MgO content decreases or FeO content increases. Weakly magnetic. It is more soluble in hydrofluoric acid and slowly dissolves in hot hydrochloric acid. Dissolved in phosphoric acid and cooled and diluted, add sodium peroxide or hydrogen peroxide, the solution is yellow-brown or orange-yellow. Ilmenite can be produced in all kinds of rocks, in the basal rock and acidic rock is widely distributed; produced in pegmatite, the particle size is larger, up to several centimeters. When the ore-bearing host rock is destroyed by weathering, ilmenite can be transferred to the sand ore.

The chemical composition of ilmenite is FeTiO3, and the crystals are oxide minerals of the tripartite crystal system. The English name comes from the original discovery of the origin of this mineral in the Urals, Russia, Ilmen Mountain (Ильменский горы). Containing TiO252.66%, it is the most important mineral raw material for extracting titanium and titanium dioxide. The crystals are often plate-like, and the aggregates are massive or granular. Steel gray to iron black, streak black to maroon, semi-metallic luster. Morse hardness 5~6, specific gravity 4.70~4.78, with weak magnetism. Ilmenite is generally found as a by-mineral in igneous and metamorphic rocks, and can also form alluvial ores. Famous mines include Ilmen Mountain in Russia, Kragler in Norway, Iron Mountain in Wyoming, USA, and Lake Ellard in Quebec, Canada. The Panzhihua Iron Mine in Sichuan, China, is also a large ilmenite producer with ilmenite in microscopic grains or flakes distributed between magnetite grains or in cleavage.

ilmenite

FeO47.36, TiO52.64. Fe2 and Mg2, Mn2 can be replaced by a complete homogeneous homogeneity, forming FeTiO3-MgTiO3 or FeTiO3-MnTiO3 series. When FeO is dominant, it is called ilmenite, when MgO is dominant, it is called magnesite, and when MnO is dominant, it is called red titanomanganite. Often have Nb, Ta and other analogous homogeneous substitution. At a high temperature of >960°C, FeTiO3-Fe2O3 can form a complete solid solution. With a decrease in temperature, at about 600 ℃, FeTiO3-Fe2O3 solid solution out of solution, precipitated in ilmenite hematite lamellar crystals, and ∥ (0001) directional arrangement.

Morphology

Tripartite crystal system, arh=0.553nm, α=54?49';Z=2. or ah=0.509nm, ch=1.407nm;Z=6. It can be regarded as a derivative of corundum-type structure. The difference is that the position of Al3 in corundum is replaced by Fe2, Ti4 and arranged between them, resulting in the disappearance of c slip surface, so that the space group is changed from R3c to R3.

At high temperature ilmenite in Fe, Ti is disordered distribution and has a hematite structure (i.e., corundum-type structure), so the formation of FeTiO3-Fe2O3 solid solution, the composition of which can be expressed as Fe32- xFex2Tix4O3 (x represents the molar fraction of ilmenite). The space group transforms from R3c to R3 at temperatures ranging from 1100 °C (x = 0.65) to 600 °C (x = 0.45). When 0.6>x≥0.5, a fully ordered structure with the space group as R3 cannot be obtained; at x=0.5, the transformation of R3c?R3 to a substable state and the solid solution begins to partially exsolve. Rhombic crystals. Often irregular grains, scales or thick plates. Above 950 ℃ ilmenite and hematite form a complete homogeneous homogeneity. When the temperature decreases, that is, melting away, so ilmenite often contains small scale-like hematite inclusion. The color of ilmenite is iron black or steel gray. Streaks are steel gray or black. Hematite inclusions are brown or reddish brown streaks. Metallic-semi-metallic luster. Opaque, no resolution. Hardness 5-6.5, specific gravity 4-5. weakly magnetic. Ilmenite occurs mainly in ultramafic, basaltic, alkaline, acidic and metamorphic rocks. China's Panzhihua vanadium and titanium magnetite beds, ilmenite is granular or flaky distribution of titanomagnetite and other minerals between the particles, or along the titanomagnetite cleavage surface into a directional lamellar crystals.

Types of ilmenite

ilmenite, often as a by-mineral, or in the basal, ultramafic rocks dispersed in the magnetite in the form of strips and flakes, and recalcitrant pyroxene, plagioclase feldspar and other **** born. Pegmatitic ilmenite, produced in granitic pegmatites, with microplagioclase feldspar, muscovite, quartz, magnetite etc.**** born. Titanium ilmenite tends to be enriched in alkaline rocks. Because of its chemical stability, it can form alluvial sand mines, which are ****-born with magnetite, rutile, zircon, monazite, and so on. It can be distinguished from hematite or magnetite according to crystal shape, striation, and weak magnetism. Ilmenite is the most important titanium ore mineral.

Properties Physical Properties

Iron black or steel gray; streaks steel gray or black. Brown or maroon color with hematite inclusions. Metallic to semi-metallic luster. Opaque. No resolution. Sometimes appearing or cracking. Hardness 5~5.5. brittle. relative density 4.0~5.0. weakly magnetic. Relative density 4.0~5.0. weakly magnetic.

Under polarized light: deep red, opaque or slightly transparent. Uniaxial crystal (-). Very high refractive index (N=2.7) and refractive index.

Chemical Properties

The ilmenite used in the experiments is a natural ore and the reducing agent is charcoal powder. The main phases in the ore are CaO, MgO, SiO2, Al2O3, MnO2, V2O5 and Cr2O3. The composition of the ore is 47.86% TiO2, 35.12% Fe, 0.22% CaO, 2.01% MgO, 1.86% SiO2, 0.70%. The particle size of the ore was less than 0.087 mm, and the particle size of the charcoal powder was less than 0.076 mm. the ore and the charcoal powder were dried at 105°C for 24 h, and then mixed in a certain proportion and pressed into blocks. The carbon content in the mixture was 20%. In the microwave carbothermal reduction process, the temperature of the material is gradually increased. It takes 3-8min to heat the material from room temperature to 1123-1263K by microwave, and it is found that: the reduction reaction of ilmenite starts from the first application of microwave, which indicates that the microwave carbothermal reduction reaction of ilmenite has started even under the condition of very low temperature. This property of ilmenite is mainly due to the fact that a portion of the microwave energy undergoes local coupling*** vibration and generates hot spots. The temperature of these hot spots is much higher than that of other regions, and thus they generate chemical reactions, with the center of the hot spot being the center of the reaction. In addition, atoms or molecules will vibrate vigorously at the center of the reaction and will be better able to meet the conditions of the chemical reaction, which will also lower the temperature at which the chemical reaction is initiated. It is because of the existence of these hot spots and the intense vibration of molecules or atoms, the microwave carbothermal reduction reaction of ilmenite can be carried out at lower temperatures, which greatly reduces the energy consumption of the carbothermal reduction process of ilmenite.

ilmenite

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

Reaction formula: FeTiO3+C=Fe+TiO2+CO(1)FeTiO3+CO=Fe+TiO2+CO2(2)CO2+C=2CO(3)The rate of reaction is accelerated with the increase of carbon content, and the rate of reaction is independent of the carbon content when the carbon content is greater than 20%. The rate of microwave reduction is much faster than conventional reduction. According to the ilmenite microwave carbothermal reduction and conventional carbothermal reduction study of comparative experiments show that: ilmenite microwave reduction rate is much faster than the conventional reduction, at 1153K, the rate of microwave carbothermal reduction is 79.06 times that of the conventional reduction. The rate of microwave reduction at 1153 K can be compared with that of conventional reduction at 1422 K. The temperature difference between the two is as high as 269 K. This also shows that the carbothermal reduction of ilmenite can be carried out at a lower temperature when microwave heating is used instead of conventional heating.

Similar to the carbothermal reduction of iron ore, the carbothermal reduction of ilmenite is a strong heat-absorbing reaction (ΔH=+181kJ/molFeTiO3), which also produces a "cold center" when reduced by conventional heating. As microwave can be rapid overall heating of the material, the "cold center" of the problem is naturally solved, and thus the reaction rate is significantly accelerated.

History

Titanium can also form many compounds, they also have a variety of special properties and uses, such as titanium dioxide, is a snow-white powder, it is the best white pigment, commonly known as "titanium dioxide", 1 gram of titanium dioxide can be more than 450 square centimeters of the area coated with snow white. The titanium dioxide used as white pigment in the world, more than hundreds of thousands of tons a year. If the titanium dioxide added to the paper, can make the paper white and opaque, so the manufacture of banknotes and art with the paper, sometimes have to add titanium dioxide, in addition, in order to make the color of the plastic becomes lighter, so that the rayon luster is soft, and sometimes also have to add titanium dioxide. Titanium dioxide is known as the whitest thing in the world. Most of the titanium in nature is in a dispersed state, the main formation of the mineral ilmenite TeTiO3 and rutile TiO2, and vanadium ilmenite and so on. China's Sichuan Panzhihua area is extremely rich in vanadium ilmenite, reserves of about 1.5 billion tons.

So, how was titanium discovered?1791, the British scientist Gregor found an ore in the suburbs of Minahan - black magnetic sand, through the study of this ore, he believes that there is a new chemical element in the ore. He named this new element after the place where he found the ore, "Minahan".

After four years, the German chemist Klaproth from Hungary Buynik in a red ore, found this new element, he used the Greek mythology, "too Dan" in the name of the name of the race (in Chinese according to the translation of the name of the original, named titanium), Klaproth also pointed out that Grigor found the new element "Mignonhan" is titanium, but at that time, in fact, found all Powdered titanium dioxide rather than titanium metal. Until 1910, the American chemist Hendel was the first time to produce 99.9% purity of titanium metal, but the total **** less than 1 gram. From the discovery of titanium to the production of titanium metal, before and after the experience of 120 years, to 1947, people began to refine titanium in factories, when the annual output of only 2 tons. By 1955, production had surged to 20,000 tons. By 1972, annual production reached 200,000 tons. The use of titanium is becoming more and more widespread, and it is being increasingly emphasized, and people call it the steel of the future, the metal of the 21st century.

Smelting methods

ilmenite smelting sulfuric acid method and chlorination method, the two methods are only different in the treatment of titanium ore: sulfuric acid method can be used to lower grade ilmenite ore, but also the production of ferrous sulfate low cost, but too much pollution by-products are difficult to deal with the consumption of sulfuric acid; chlorination method using higher grade ore and higher costs, but less pollution by-products less chlorine and can be recycled. Use. But both methods are titanium ore into pure titanium dioxide, and then pure titanium dioxide and pure chlorine and coke at high temperatures to generate titanium tetrachloride and carbon monoxide, with the metal of calcium, magnesium or sodium will be reduced to spongy titanium metal large-scale production of titanium methods:

ilmenite

The first step: at high temperatures, the rutile (TiO2) and charcoal powder (C) mixed, and chlorine gas to produce TiCl4 and a flammable gas CO.

The second step: in the argon (Ar) environment, with an excess of magnesium (Mg) in the heating conditions and TiCl4 reaction to produce titanium metal (argon does not take part in the reaction)

Significance of the study

Yunnan is a kingdom of non-ferrous metals, non-ferrous metal development naturally pay more attention to the metallurgical technology is changing day by day, the efficiency is the effectiveness of the study. This study fills the vacancy of microwave reduction of ilmenite, and provides a theoretical basis and methodological guidance for the industrial use of microwave carbothermal reduction of ilmenite. The microwave carbothermal reduction of ilmenite can make the reaction rate faster, because the microwave carbothermal reduction of ilmenite can be carried out at a lower temperature, so the use of energy will be greatly reduced for the energy shortage of China undoubtedly has a great scientific value and economic value. It is believed that this research will be used in the industrial field to produce good economic and social benefits.

ilmenite distribution Industrial application

Pure titanium is a silvery-white metal. Titanium minerals are widely distributed in nature, accounting for about 0.6% of the weight of the earth's crust, second only to aluminum, iron, calcium, sodium, potassium and magnesium, and more than copper, tin, manganese, zinc and so on in the earth's crust to be several times or even dozens of times the content. The melting point of titanium is 1725 ℃, its main feature is the density is small but strong. Compared with steel, its density is only equivalent to 57% of steel, while the strength and hardness is similar to steel. Compared with aluminum, aluminum density is smaller than titanium, but the mechanical strength is very poor. Therefore, titanium has the advantages of both steel (high strength) and aluminum (light weight). Pure titanium has good plasticity, its toughness more than 2 times pure iron, heat and corrosion resistance is also very good.

Because titanium has these advantages, so since the 1950s, a leap to become a prominent rare metal. Titanium and its alloys, first used in the manufacture of aircraft, rockets, missiles, ships and other aspects, began to promote the use of chemical and petroleum sectors. For example, in the supersonic aircraft manufacturing, due to such aircraft in high-speed flight, the surface temperature is high, with aluminum alloy or stainless steel, at this temperature has lost its original performance and titanium alloy in the 550 ° C and above still maintain good mechanical properties, so it can be used to manufacture more than the speed of sound 3 times the high-speed aircraft. The amount of titanium used in this aircraft to account for 95% of the total weight of its structure, so there is a "titanium aircraft," the name, about half of the world's more than titanium, used to manufacture aircraft fuselage and jet engine parts. Titanium in the atomic energy industry, for the manufacture of nuclear reactors, the main parts in the chemical industry, titanium is mainly used in the manufacture of various containers, reactors, heat exchangers, pipelines, pumps and valves. If titanium is added to stainless steel, only one percent or so, it greatly improves the rust resistance.