The Becher process is an industrial process used to produce

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at visible wa ...

, a form of

titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insoluble ...

, from the ore

ilmenite 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 titanium and the main source of titanium dioxide, which is used in paints, printing ...

. It is competitive with the chloride process and the sulfate process, which achieve similar net conversions. With the idealized formula FeTiO₃, ilmenite contains 55-65%

, the rest being

iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of w ...

. The Becher process, like other beneficiation processes, aims to remove iron. The Becher process exploits the conversion of the ferrous iron (FeO) to ferric iron (Fe₂O₃).

History

This technology was developed in the early 1960s in

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to ...

by a joint initiative between industry and government. The process was named after Robert Gordon Becher, who while working at the Western Australian Government Chemical Laboratories (the precursor to ChemCentre) invented, developed and introduced the technique to the Western Australian Mineral Sands industry. The process was patented in 1961.

Process

The Becher process is suitable for weathered ilmenite that has low

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'' ...

s of

chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and h ...

and

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

. There are four steps involved in removing the iron portion of the ilmenite: #

Oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

# Reduction #

Aeration Aeration (also called aerification or aeriation) is the process by which air is circulated through, mixed with or dissolved in a liquid or other substances that act as a fluid (such as soil). Aeration processes create additional surface area i ...

# Leaching

Oxidation

Oxidation involves heating the ilmenite in a rotary kiln with air to convert iron to iron(III) oxide: : 4 FeTiO₃ + O₂ → 2 Fe₂O₃·TiO₂ + 2 TiO₂ This step is suitable for a range of ilmenite-containing feedstocks.

Reduction

Reduction is performed in a rotary kiln with pseudobrookite (Fe₂O₃.TiO₂), coal, and sulfur, then heated to a temperature greater than 1200 °C. The iron oxide in the mineral grains is reduced to metallic iron to produce reduced ilmenite: : Fe₂O₃·TiO₂ + 3 CO → 2 Fe + TiO₂ + 3 CO₂ The "reduced ilmenite" is separated from the char prior to the next step.

Aeration

Aeration involves the removal of the metallic iron created in the last step by "rusting" it out. This conversion is achieved in large tanks that contain 1% ammonium chloride solution with air being pumped through the tank. The tank is being continuously agitated, and the iron will rust and precipitate in the form of a slime. : 4 Fe + 3 O₂ → 2 Fe₂O₃ The finer iron oxide is then separated from the larger particles of synthetic rutile.

Acid leach

Once the majority of the iron oxide has been removed the remainder of it is leached away using 0.5M sulfuric acid.