For more information, please visit our website.
Ilmenite is a titanium-iron oxide mineral with the idealized formula FeTiO
3. It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium[5] and the main source of titanium dioxide, which is used in paints, printing inks,[6] fabrics, plastics, paper, sunscreen, food and cosmetics.[7]
Structure and properties
[
edit
]
Ilmenite is a heavy (specific gravity 4.7), moderately hard (Mohs hardness 5.6 to 6), opaque black mineral with a submetallic luster.[8] It is almost always massive, with thick tabular crystals being quite rare. It shows no discernible cleavage, breaking instead with a conchoidal to uneven fracture.[9]
Ilmenite crystallizes in the trigonal system with space group R3.[10][3] The ilmenite crystal structure consists of an ordered derivative of the corundum structure; in corundum all cations are identical but in ilmenite Fe2+ and Ti4+ ions occupy alternating layers perpendicular to the trigonal c axis.
Pure ilmenite is paramagnetic (showing only very weak attraction to a magnet), but ilmenite forms solid solutions with hematite that are weakly ferromagnetic and so are noticeably attracted to a magnet. Natural deposits of ilmenite usually contain intergrown or exsolved magnetite that also contribute to its ferromagnetism.[8]
Ilmenite is distinguished from hematite by its less intensely black color and duller appearance and its black streak, and from magnetite by its weaker magnetism.[9][8]
Crystal structure of ilmenite
Ilmenite from Froland, Aust-Agder, Norway; 4.1 × 4.1 × 3.8 cm
Ilmenite and hematite under normal light
Ilmenite and hematite under polarized light
Discovery
[
edit
]
In William Gregor discovered a deposit of black sand in a stream that runs through the valley just south of the village of Manaccan (Cornwall), and identified for the first time titanium as one of the constituents of the main mineral in the sand.[11][12][13] Gregor named this mineral manaccanite.[14] The same mineral was found in the Ilmensky Mountains, near Miass, Russia, and named ilmenite.[9]
Mineral chemistry
[
edit
]
Pure ilmenite has the composition FeTiO3. However, ilmenite most often contains appreciable quantities of magnesium and manganese and up to 6 wt% of hematite, Fe2O3, substituting for FeTiO3 in the crystal structure. Thus the full chemical formula can be expressed as (Fe,Mg,Mn,Ti)O3.[8] Ilmenite forms a solid solution with geikielite (MgTiO
3) and pyrophanite (MnTiO
3) which are magnesian and manganiferous end-members of the solid solution series.[3]
Although ilmenite is typically close to the ideal FeTiO
3 composition, with minor mole percentages of Mn and Mg,[3] the ilmenites of kimberlites usually contain substantial amounts of geikielite molecules,[15] and in some highly differentiated felsic rocks ilmenites may contain significant amounts of pyrophanite molecules.[16]
At temperatures above 950 °C (1,740 °F), there is a complete solid solution between ilmenite and hematite. There is a miscibility gap at lower temperatures, resulting in a coexistence of these two minerals in rocks but no solid solution.[8] This coexistence may result in exsolution lamellae in cooled ilmenites with more iron in the system than can be homogeneously accommodated in the crystal lattice.[17] Ilmenite containing 6 to 13 percent Fe2O3 is sometimes described as ferrian ilmenite.[18][19]
Ilmenite alters or weathers to form the pseudo-mineral leucoxene, a fine-grained yellowish to grayish or brownish material[8][20] enriched to 70% or more of TiO2.[19] Leucoxene is an important source of titanium in heavy mineral sands ore deposits.[21]
Paragenesis
[
edit
]
Ilmenite is a common accessory mineral found in metamorphic and igneous rocks.[3] It is found in large concentrations in layered intrusions where it forms as part of a cumulate layer within the intrusion. Ilmenite generally occurs in these cumulates together with orthopyroxene[22] or in combination with plagioclase and apatite (nelsonite).[23]
Magnesian ilmenite is formed in kimberlites as part of the MARID association of minerals (mica-amphibole-rutile-ilmenite-diopside) assemblage of glimmerite xenoliths.[24] Manganiferous ilmenite is found in granitic rocks[16] and also in carbonatite intrusions where it may also contain anomalously high amounts of niobium.[25]
Many mafic igneous rocks contain grains of intergrown magnetite and ilmenite, formed by the oxidation of ulvospinel.[18]
Processing and consumption
[
edit
]
Tellnes opencast ilmenite mine, Sokndal, NorwayMost ilmenite is mined for titanium dioxide production.[26] Ilmenite and titanium dioxide are used in the production of titanium metal.[27][28]
Titanium dioxide is most used as a white pigment and the major consuming industries for TiO2 pigments are paints and surface coatings, plastics, and paper and paperboard. Per capita consumption of TiO2 in China is about 1.1 kilograms per year, compared with 2.7 kilograms for Western Europe and the United States.[29]
Estimated world production of titanium concentrate by mineral source in metric tons, &#;. Titanium concentrate is mainly obtained from processing of ilmenite mineral, followed by titaniferous slags and natural rutile.Titanium is the ninth most abundant element on Earth and represents about 0.6 percent of the Earth's crust. Ilmenite is commonly processed to obtain a titanium concentrate, which is called "synthetic rutile" if it contains more than 90 percent TiO2, or more generally "titaniferous slags" if it has a lower TiO2 content. More than 80 percent of the estimated global production of titanium concentrate is obtained from the processing of ilmenite, while 13 percent is obtained from titaniferous slags and 5 percent from rutile.[30]
Ilmenite can be converted into pigment grade titanium dioxide via either the sulfate process or the chloride process.[31] Ilmenite can also be improved and purified to titanium dioxide in the form of rutile using the Becher process.[32]
Ilmenite ores can also be converted to liquid iron and a titanium-rich slag using a smelting process.[33]
Ilmenite ore is used as a flux by steelmakers to line blast furnace hearth refractory.[34]
Ilmenite can be used to produce ferrotitanium via an aluminothermic reduction.[35]
Feedstock production
[
edit
]
Various ilmenite feedstock grades.[36] FeedstockTiO
2
Link to GIANT ANODE
Content Process (%) Ore <55 Sulfate Ore >55 Chloride Ore <50 Smelting (slag) Synthetic rutile 88&#;95 Chloride Chloride slag 85&#;95 Chloride Sulfate slag 80 SulfateMost ilmenite is recovered from heavy mineral sands ore deposits, where the mineral is concentrated as a placer deposit and weathering reduces its iron content, increasing the percentage of titanium. However, ilmenite can also be recovered from "hard rock" titanium ore sources, such as ultramafic to mafic layered intrusions or anorthosite massifs. The ilmenite in layered intrusions is sometimes abundant, but it contains considerable intergrowths of magnetite that reduce its ore grade. Ilmenite from anorthosite massifs often contain large amounts of calcium or magnesium that render it unsuitable for the chloride process.[39]
The proven reserves of ilmenite and rutile ore are estimated at between 423 and 600 million tonnes titanium dioxide. The largest ilmenite deposits are in South Africa, India, the United States, Canada, Norway, Australia, Ukraine, Russia and Kazakhstan. Additional deposits are found in Bangladesh, Chile, Mexico and New Zealand.[40]
Australia was the world's largest ilmenite ore producer in , with about 1.3 million tonnes of production, followed by South Africa, Canada, Mozambique, India, China, Vietnam, Ukraine, Norway, Madagascar and United States.
The top four ilmenite and rutile feedstock producers in were Rio Tinto Group, Iluka Resources, Exxaro and Kenmare Resources, which collectively accounted for more than 60% of world's supplies.
The world's two largest open cast ilmenite mines are:
TiO
2
Major mineral sands based ilmenite mining operations include:
Attractive major potential ilmenite deposits include:
Fe
, 13.7%TiO
2
V
2
5
In , China has by far the highest titanium mining activity. About 35 percent of the world&#;s ilmenite is mined in China, representing 33 percent of total titanium mineral mining (including ilmenite and rutile). South Africa and Mozambique are also important contributors, representing 13 percent and 12 percent of worldwide ilmenite mining, respectively. Australia represents 6 percent of the total ilmenite mining and 31 percent of rutile mining. Sierra Leone and Ukraine are also big contributors to rutile mining.[30]
China is the biggest producer of titanium dioxide, followed by the United States and Germany. China is also the leader in the production of titanium metal, but Japan, the Russian Federation and Kazakhstan have emerged as important contributors to this field.
Patenting activities
[
edit
]
Patent activity on titanium dioxide production from ilmenite has increased since .Patenting activity related to titanium dioxide production from ilmenite is rapidly increasing.[30] Between and , there have been 459 patent families that describe the production of titanium dioxide from ilmenite, and this number is growing rapidly. The majority of these patents describe pre-treatment processes, such as using smelting and magnetic separation to increase titanium concentration in low-grade ores, leading to titanium concentrates or slags. Other patents describe processes to obtain titanium dioxide, either by a direct hydrometallurgical process or through two industrially exploited processes, the sulfate process and the chloride process. Acid leaching might be used either as a pre-treatment or as part of a hydrometallurgical process to directly obtain titanium dioxide or synthetic rutile (>90 percent titanium dioxide, TiO2). The sulfate process represents 40 percent of the world&#;s titanium dioxide production and is protected in 23 percent of patent families. The chloride process is only mentioned in 8 percent of patent families, although it provides 60 percent of the worldwide industrial production of titanium dioxide.[30]
Key contributors to patents on the production of titanium dioxide are companies from China, Australia and the United States, reflecting the major contribution of these countries to industrial production. Chinese companies Pangang and Lomon Billions Groups are the main contributors and hold diversified patent portfolios covering both pre-treatment and the processes leading to a final product.
In comparison, patenting activity related to titanium metal production from ilmenite remains stable.[30] Between and , there have been 92 patent families that describe the production of titanium metal from ilmenite, and this number has remained quite steady. These patents describe the production of titanium metal starting from mineral ores, such as ilmenite, and from titanium dioxide (TiO2) and titanium tetrachloride (TiCl4), a chemical obtained as an intermediate in the chloride process. The starting materials are purified if needed, and then converted to titanium metal by a chemical reduction process using a reducing agent. Processes mainly differ in regard to the reducing agent used to transform the starting material into titanium metal: magnesium is the most frequently cited reducing agent and the most exploited in industrial production.
Key players in the field are Japanese companies, in particular Toho Titanium and Osaka Titanium Technologies, both focusing on reduction using magnesium. Pangang also contributes to titanium metal production and holds patents describing reduction by molten salt electrolysis.[30]
Lunar ilmenite
[
edit
]
Ilmenite has been found in lunar samples, particularly in high-Ti lunar mare basalts common from Apollo 11 and Apollo 17 sites, and on average, constitutes up to 5% of lunar meteorites.[46] Ilmenite has been targeted for ISRU water and oxygen extraction due to a simplistic reduction reaction which occurs with CO and H2 buffers.[47][48][49]
Sources
[
edit
]
This article incorporates text from a free content work. Licensed under CC-BY. Text taken from Production of titanium and titanium dioxide from ilmenite and related applications&#;, WIPO.
References
[
edit
]
As of , the total global production volume of ilmenite amounted to an estimated 8.9 million metric tons of titanium dioxide equivalent, while rutile production amounted to an estimated 590,000 metric tons of titanium dioxide equivalent, amounting to a total global titanium production of 9.49 million metric tons. China dominates global titanium production overall, as the largest producer of ilmenite, titanium sponge, and titanium dioxide. Other leading titanium mineral producers are Mozambique, South Africa, Japan, Russia, and Australia , among others, depending on the specific mineral or form of titanium. Interestingly, most of the world&#;s titanium is produced in countries that are considered politically unstable The United States is the world&#;s largest exporter of titanium and articles thereof, while simultaneously being the world&#;s largest importer of another category of titanium: unwrought, waste or scrap, or powder. Meanwhile, China is the world&#;s largest exporter of titanium oxides and Germany is the largest importer of that product category. Because of the variety of titanium products on the market, prices for titanium are also varied. For instance, the Australian price of bulk rutile with a minimum titanium dioxide content of 95 percent, free on board, was 1,500 U.S. dollars per metric ton as of , while the average unit value price of one metric ton of ilmenite imported to the U.S. was 290 U.S. dollars in the same year.
Titanium is a chemical element that is only found in nature as titanium oxide. Through processing, titanium metal, which is a transition metal with a silver color, is produced. Despite its low density, titanium metal is very strong, as well as being resistant to corrosion from sea water and other chemicals. These properties, as well as the fact that titanium can be alloyed with a variety of metals, make titanium an industrially important commodity. In addition to titanium metal, there are other forms of titanium, such as the powder titanium dioxide (often used as a pigment), or titanium sponge, which is produced during the multiple step process to produce the metal. As of , the total global reserves of titanium minerals amounted to an estimated 650 million metric tons of ilmenite and 49 million metric tons of rutile. The country with the largest titanium reserves overall that year was China.
If you want to learn more, please visit our website titanium sheet supplier.