Cristal

Cristal Global

Titanium dioxide pigment (TiO₂) is a white powder with high opacity, brilliant whiteness, excellent covering power and resistance to colour change. These properties have made it a valuable pigment and opacifier for a broad range of applications in paints, plastic goods, inks and paper.

The pigment is manufactured by processing naturally occurring the titanium-containing rutile or ilmenite minerals. Rutile is an impure form of titanium dioxide whereas ilmenite contains titanium combined with iron as a compound oxide. Though common throughout the world, they are most readily exploited in Australia, USA, India and South Africa.

In Australia nearly all titanium dioxide is produced from ilmenite as it naturally occurs in accessible high concentrations and in a form which allows the ready extraction of the rutile. These favourable factors have made ilmenite a competitive raw material for Australia’s producers reflected in high export activity.

Low energy cost regions use the slagging process.

Australia supplies about 40 per cent of the world’s ilmenite and about 25 per cent of its rutile. In contrast to its dominance in titanium minerals, Australia supplies only about a 3 per cent share of the world’s titanium dioxide pigment production of around 4 million tonnes. This imbalance implies significant opportunity for adding further value.

In 1995, Western Australia produced 160 000 tonnes of titanium dioxide pigment valued at around $350 million.

By June 1998, Australia is anticipated to export A$1.1 bn of titanium minerals of which two-thirds is exported to Europe and North America.

Technologies

Titanium dioxide pigment may be manufactured by either the sulfate or the chlorine process (Australia now only use the chlorine process). The technology for the chloride process is tightly held and Ticor is license by Kerr McGee under which brand name it also markets its pigment.

Sulfate process

The sulfate process was the first commercial scale technology used to convert ilmenite to titanium dioxide. Producing large quantities of waste iron sulfate and producing an inferior product for most applications, few sulfate process plants are now being built. In 1996, Tioxide, a sulfate-based plant at Burnie, Tasmania, ceased operation after some forty years in operation using ilmenite shipped from Western Australia and local sulfuric acid from metal smelting operations in Tasmania. The plant produced large volumes of iron sulfate waste product. The sulfate process produces a form of pigment called anatase, which is preferred over chloride-derived pigment for use on papers, ceramics and inks.

In cheap electricity locations such as South Africa (coal power) and Norway (hydro power), the ilmenite may be slagged to produce rutile and iron. In Australia, the Becher process produces iron oxide as waste which is retuned to the mine site.

Chloride process

The newer chloride process avoids the iron sulfate waste problem and, at larger scales, is cheaper to operate. This process requires the ilmenite to be processed to the rutile form (ie. removal of the iron component to yield crude titanium dioxide [synthetic rutile]) for which the Becher process was developed in Western Australia. Typically 1.06 tonnes of synthetic rutile is required for each tonne of pigment.

The chlorine process, as now exclusively used in Australia, reacts chlorine with synthetic rutile to form volatile titanium tetrachloride which is then oxidised leaving behind iron chloride and other impurities with the bulk of the chlorine re-cycled. Consumption of chlorine is therefore related to the amount of iron oxide (and alumina) left in the synthetic rutile which is typically 4 per cent. As iron chloride is environmentally harmful it is treated with lime to convert it to iron oxides and the calcium chloride drained to sea.

About one tonne of chlorine is required to produce 5 to 6 tonnes of titanium dioxide pigment (depending on the iron content of the rutile used consuming the chlorine as ferric chloride and with about one-third of chlorine ending up as hydrogen chloride). Tiwest is now supplying hydrochloric acid to Coogee for conversion to ammonium chloride (for use in synthetic rutile production).

By using rutile (and not the iron-containing ilmenite), the chloride plants avoid the production of much larger amounts of iron chloride that has to be disposed off (eg. by deep well disposal as used by Dupont of the USA).

After removal of vanadium salts, and further fractional distillation, the pure titanium tetrachloride is reacted with oxygen at high temperature to produce titanium dioxide. The titanium dioxide is ground and coated to different grades. The liberated chlorine is recycled. In other words, chlorine is larely consumed as iron chloride which is converted to iron hydroxide after treating with lime. The resultant calcium chloride and iron oxide can be safely disposed.

Worldwide there is a marked swing to the use of the chloride process with few new sulfate plants being established. The chloride process offers tighter product control, less labour intensive, and environmentally safer. Currently about about 60 per cent of the 4 million tonnes of pigment produced produced world-wide is produced by the chlorine process. Though declining in response to concerns about environmentally unacceptable waste, many sulfate plants have introduced innovative techniques deferring their closure. This status is contributing to depress prices for synthetic rutile.

The chloride plants require a high grade of rutile. The lower grades of ilmenite (52 to 57 per cent titanium dioxide) are exported by West Australian titanium mineral producers to oveseas sulfate-based plants and electric arc furnaces. The producers claim the lower grades of ilmenite could not be economically converted to synthetic rutile in the current world status of cheap slagged ilmenite (with zero nucleide content).

The nucleide issue is that the mineral sands contain monazite which typically contains 6 per cent of the radioactive element thorium (and some uranium. In 1990, some 13 000 tonnes of monazite were produced but fell to zero due to competition from nucleide free sources such as China. There is interest in processing monazite by Rhone-Poulenc at Pinjarra.

The Industry

About 40 per cent of the state’s ilmenite production (about $80 per tonne) is converted to synthetic rutile ($470 per tonne) and of that 40 per cent, only about 30 per cent is converted to the pigment (valued at about $2 000 per tonne). In other words, pigment production could increase eight-fold!

There are two manufacturers of titanium dioxide pigment in Western Australia, Millennium International Chemicals (MIC, formerly SCM Chemicals Ltd) at Kemerton, Western Australia and Tiwest Joint Venture at Kwinana, Western Australia.

Cristal Global is the second largest titanium dioxide producer in the world, the largest producer of merchant titanium chemicals, and the leading manufacturer of specialty titanium products.

Cristal Global provides numerous products and services for a variety of industries around the world. From coatings to paper and polymers to pigments, our products and services are used to improve everyday life – a brighter paint, a tighter seal, a special ink.

Thousands of products in our world, from plastic bags to aerospace parts, get their start with help from Cristal Global.

Cristal Global and its nearly 4,000 employees on five continents are proud leaders in manufacturing titanium dioxide products. We are passionate about pursuing perfection in our work, providing for our family of employees, and creating a cleaner, brighter future with the products we make.

Cristal Global provides products spanning a broad cross-section of industries. Many of the every day quality-of-life products around you – paint, paper, plastics, titanium metal – contain components from Cristal Global.