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Ilmenite

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Ilmenite is a titanium-iron(II) oxide mineral that serves a vital role in modern industry. It is a heavy, opaque solid with a black or steel-gray color and a submetallic luster. As the most important ore of titanium, it is the primary source for producing titanium dioxide. This chemical compound is a brilliant white pigment used globally. You can find it in paints, printing inks, plastics, paper, and even in cosmetics and sunscreen.

Tellnes
Tellnes

The internal structure of ilmenite is quite specific and organized. It crystallizes in the trigonal system, which describes the geometric shape of its crystals. The structure is an ordered derivative of the corundum structure. In corundum, all cations are identical, but in ilmenite, they are different. Specifically, Fe2+ and Ti4+ ions occupy alternating layers perpendicular to the trigonal c axis. This precise arrangement of ions defines how the mineral behaves and how it can be processed.

Relevant patent families describing titanium dioxide production from ilmenite, 2002–2021
Relevant patent families describing titanium dioxide production from ilmenite, 2002–2021

Ilmenite possesses interesting magnetic properties depending on its purity. Pure ilmenite is paramagnetic, meaning it shows only a very weak attraction to a magnet. However, it often forms solid solutions with hematite, making it weakly ferromagnetic. This means it can be noticeably attracted to magnets. Natural deposits also frequently contain intergrown or exsolved magnetite. This magnetite adds to the mineral's ferromagnetism, which helps workers separate it from other materials. You can distinguish ilmenite from hematite by its duller appearance and black streak.

The history of this mineral began with a discovery in the late 18th century. In 1791, William Gregor found a deposit of black sand in a stream. This stream flowed through a valley south of Manaccan in Cornwall. Gregor identified titanium as a constituent of the main mineral in that sand. He originally named the mineral manaccanite. Later, the same mineral was discovered in the Ilmensky Mountains near Miass, Russia. Because of this Russian location, the name ilmenite was adopted.

Chemically, ilmenite is complex and often contains other elements. While pure ilmenite is FeTiO3, it usually contains magnesium and manganese. It can also contain up to 6 wt% of hematite. This creates a solid solution series with minerals like geikielite and pyrophanite. In certain environments, like kimberlites, ilmenite contains substantial amounts of geikielite. In other rocks, it may contain significant pyrophanite. When ilmenite weathers, it can turn into a pseudo-mineral called leucoxene. Leucoxene is yellowish or brownish and is enriched to 70% or more with titanium dioxide.

Worldwide mining of the titanium-containing minerals ilmenite and rutile
Worldwide mining of the titanium-containing minerals ilmenite and rutile

Processing ilmenite is a major global industrial undertaking. Most ilmenite is mined to produce titanium dioxide via the sulfate process or the chloride process. Another method, the Becher process, can purify ilmenite into rutile. Some ores are even converted into liquid iron and titanium-rich slag through smelting. Beyond pigments, ilmenite can produce ferrotitanium through aluminothermic reduction. It is also used by steelmakers as a flux to line the hearth of blast furnaces.

Tellnes
Tellnes

Global production numbers show how important this mineral is to the economy. In 2011, Australia was the largest producer, yielding about 1.3 million tonnes of ore. China is a massive player, mining about 35 percent of the world's ilmenite in 2020. The industry involves massive operations like the Tellnes mine in Norway and the Lac Tio mine in Canada. The largest deposits are located in South Africa, India, the United States, and several other nations. These resources support a massive supply chain for the materials we use every day.

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🖼️ Images & Media (4)
File:Tellnes.jpg
Tellnes.jpg
File:Estimated world production of titanium concentrate by mineral source in metric tons, 2015–2019.png
Estimated world production of titanium...
File:Worldwide mining of the titanium-containing minerals ilmenite and rutile.png
Worldwide mining of the...
File:Relevant patent families describing titanium dioxide production from ilmenite, 2002–2021.png
Relevant patent families describing...
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