Usage of the ore
Titanium bearing minerals like Titaniferrous Ore (TIFe) are used in blast furnaces to protect the hearth wall against erosion. TIFe is a dense magnetite ore with a high specific gravity. It reaches the hearth at a faster rate than any of the other burden material and gets deposited there giving extensive protection.

Hearth wall erosion and formation of an elephant-foot is a common phenomenon in all blast furnaces operation. If erosion is not prevented, it may lead to hearth breakouts, cutting short the campaign life of the blast furnace. Tife ore, used as a feed material with the burden, results in an increase in the Ti contents of the hot metal. Titania is reduced in the blast furnace, which passes into liquid iron, and since it has a very strong affinity for both Carbon and Nitrogen, ultimately, the compound formed is Titanium-Carbonitride that has a melting point in excess of 3000°C and is heavy.

As a result, if proper operating discipline in blast furnace is practiced, it is possible to preferentially increase the Ti content of the hot metal, which helps in Crystallisation of the Titanium-compound that deposits on hearth wall thereby providing protection to the hearth refractories.

The advantages of the above are

  • Lowering the hearth refractory temperature.

  • The Titanium-compound layer “Patches-up” the worn out portions or exposed brick joints and thus, prevents erosion of the hearth.

  • Nitrogen Control in the hot metal.
It is an established practice all over the world to operate blast furnaces with higher Titanium contents, which ultimately gives a very safe, trouble-free and long life of the hearth. Titanium content in the hot metal is maintained between 0.08 to 0.2% depending on the condition of the hearth and the age of the furnace. Titanium also helps in the production of low Nirtogen steel. The normal requirement of this ore varies between 20-30 kg/thm. Solubility of carbon in hot metal increases with drop in Silican content of the hot metal. Titanium Carbonitride protection on the wall helps in preventing carbon pick-up from the wall with low Silicon hot metal.

There are two other sources of Titanium, Viz. Ferro-titanium and Illmenite sand. The former is generally expensive to be used in blast furnaces as feed material and Illmenite sand is available only as fines (like sand), which cannot be charged directly in a blast furnaces. Addition of Illmenite sand in sinter making causes sharp deterioration in the quality of sinter with respect to RDI. Judicious use of Titanferrous ore in blast furnace as feed material will help in achieving a trouble-free long campaign life of the blast furnace hearth. Moreover, the iron oxide part of what is charged reports to the metal after reduction and therefore, full advantage is taken of what is added at the top of the furnace.

Comparative Study - Titaniferrous Iron Ore Vs Illmenite bearing Formed Coke

Titaniferrous Iron Ore

TiFe is a dense magnetite ore with a high specific gravity. It reaches the hearth at a faster rate then any of the other burden material and gets deposit there giving extensive protection.

Average Tio2 contents = 14%

Illmenite bearing Formed Coke:

This is a briquette made from Illmenite sand and coke breeze with pitch as a binder.
Average Tio2 content = 10%

  • Technical Comparison

    1. The average Tio2 content in TiFe ore is 14% whereas in Illmenite bearing formed coke, it is 10%.

    2. TiFe ore has an added advantage of the presence of Fe that reports to the hot metal and therefore full advantage is taken from what is added at the top of the furnace, whereas, no such advantage exists in Illmenite bearing formed coke.

    3. In formed coke, pitch is usually used as a binder. The softening temperature of pitch is below 125° C while the top gas temperature of blast furnace is higher than 150°C all the time. Temperature from the top gradually increases to 1900°C at the tuyer level. As the Formed Coke travels down along with the burden, it is exposed to higher and higher temperature. The formed coke must be getting crumbled and adversely affecting the permeability and most of it getting blown out of the furnace along with the dust. Only part of Tio2 in Illmenite sand can reach high temperature zone for reduction to Ti. The Ti pick up in hot metal is poor and it further adds to the cost of hot metal without commensurating benefit of hearth protection.

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