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Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titaniumHeinz Sibum, Volker Günther, Oskar Roidl, Fathi Habashi, Hans Uwe Wolf, "Titanium, Titanium Alloys, and Titanium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. and the main source of titanium dioxide, which is used in paints, printing inks, fabrics, plastics, paper, sunscreen, food and cosmetics.
Ilmenite crystallizes in the trigonal system with space group R.
Pure ilmenite is paramagnetic (showing only very weak attraction to a magnet), but ilmenite forms 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.
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.
Although ilmenite is typically close to the ideal composition, with minor mole percentages of Mn and Mg, the ilmenites of usually contain substantial amounts of geikielite molecules, and in some highly differentiated felsic rocks ilmenites may contain significant amounts of pyrophanite molecules.
At temperatures above , 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. 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.
Ilmenite Metasomatism or Weathering to form the pseudo-mineral leucoxene, a fine-grained yellowish to grayish or brownish material enriched to 70% or more of . Leucoxene is an important source of titanium in heavy mineral sands ore deposits.
Magnesium ilmenite is formed in kimberlites as part of the MARID association of minerals (mica-amphibole-rutile-ilmenite-diopside) assemblage of Biotite . Manganese ilmenite is found in granite rocks and also in carbonatite intrusions where it may also contain anomalously high amounts of niobium.
Many mafic igneous rocks contain grains of intergrown magnetite and ilmenite, formed by the oxidation of ulvospinel.
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.
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.
Ilmenite can be converted into pigment grade titanium dioxide via either the sulfate process or the chloride process. Ilmenite can also be improved and purified to titanium dioxide in the form of rutile using the Becher process.
Ilmenite ores can also be converted to liquid iron and a titanium-rich slag using a smelting process.
Ilmenite ore is used as a flux by steelmakers to line blast furnace hearth refractory.
Ilmenite can be used to produce ferrotitanium via an aluminothermic reduction.
| +Various ilmenite feedstock grades. |
| Sulfate |
| Chloride |
| Smelting (slag) |
| Chloride |
| Chloride |
| Sulfate |
| +Estimated contained . productionUSGS 2012 Survey, p. 174 (Metric tpa x 1,000, ilmenite & rutile) |
| 247 |
| 190 |
| 250 |
| 330 |
| 246 |
| ~1,250 |
Most 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 . 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.
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.
Australia was the world's largest ilmenite ore producer in 2011, 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 2010 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:
Major mineral sands based ilmenite mining operations include:
Attractive major potential ilmenite deposits include:
In 2020, 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.
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.
In comparison, patenting activity related to titanium metal production from ilmenite remains stable. Between 2002 and 2022, 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.
/ref> Ilmenite has been targeted for ISRU water and oxygen extraction due to a simplistic reduction reaction which occurs with CO and H2 buffers.Schluter & Cowley. "Review of techniques for In-Situ oxygen extraction on the moon."
/ref>Perreault & Patience. "Ilmenite–CO reduction kinetics."
/ref>Muscatello, Tony. 2017. "Oxygen Extraction from Minerals"
/ref>
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