Uses for Kaolins - Focus on the Asian Region

Background

Kaolins are used in a variety of industries. Some of these are outlined below.

Plastics and Rubber

Leading companies such as Imerys produce surface treated minerals tailored to meet specific requirements such as that of the automotive manufacturers for use in applications where plastics with high temperatures and good dimensional stability and gloss are demanded or for items requiring cosmetic finishes whether glossy, non reflective or scratch resistant. Another example is that of calcined kaolins, some especially surface treated used to improve electrical properties of PVC and rubber-coated wires and cables, which may be used at voltages to more than 75kv.

Paints

Most surface coating producers use kaolins widely especially in decorative paints. Calcined kaolins can be a partial replacement thus reducing cost and improving opacity and whiteness.

Special clays have been developed for use in the automotive paints in electro-coat primers. Kaolin can improve sharp edge coverage leading to better corrosion resistance.

Paint Production on Asia

In 1998, world demand for paints was estimated to be around 21.5 billion litres with an annual growth rate of around 2%.  Growth in demand is expected to be faster in the Asia Pacific region offsetting lower demand in European Markets (table 1).

Table 1. Paint Demand in Various regions

Source: Roskill

The Paint Industry

The paint industry has undergone considerable rationalisation through mergers and acquisitions in the last two decades.  In 1980, the ten leading producers of paint controlled around 20% of the global market but by 1999 this had risen to around 60%.  By far the largest company in 1999 is Akzo Nobel of the Netherlands following its purchase of Courtaulds of the UK.

Industry Consolidation

Many of the leading paint companies now have operations or joint ventures in the region. Examples include: Akzo Nobel, Sherwin Williams, DuPont, Dulux, PPG Industries, BASF, Total/Sigma, Nippon Paints, Kansai and Valspar. Consolidation looks set to continue in this industry as with other. The potential size of the Asian paint market is extremely large as per capita consumption of paint within Asia is only around 2 litres compared to about 8.5 litres in Europe.   The very large variations in per capita consumption of paint between countries in Asia are clearly shown in the following table.  Future demand in paint production can be expected to be concentrated in China and India, which have the largest regional populations but amongst the lowest per capita consumption.

Table 2. Asian per capita consumption of paint by country, 1985-2005 (kg /year).

Source: Roskill / Chemical Week

Concrete

Meta-kaolin is produced by lightly calcining suitable kaolin for use as an admixture for concrete production especially where increased density to reduce “concrete-cancer” is required and for high-rise concrete needing maximum strength development. Metakaolins is blended with Portland cement in order to improve durability of concrete as it removes chemically active calcium hydroxide, reduces porosity of hardened cement and improving adhesion between the hardened cement paste and the particles of sand and aggregate.

Paper

Paper manufacturers need printed sheet brightness and gloss. Brightness enhancement is at the heart of kaolin processing. Iron, titanium and organics are the most common discolouring impurities. Historically, iron has been removed by chemical leaching, changing the form of the iron, and "washing" it from the kaolin. Floatation and settling have also long been used to remove iron and other discolouring impurities. New products must be economic to produce and affordably priced. Using technology developed and perfected over the past decades, the industry now provides the paper industry with a variety of new affordably priced high brightness kaolin products. Magnetic separation of iron and titanium involves passing slurried kaolin through a magnetic field, which is packed with fine steel wool. The iron attaches itself to the magnetized wool and is removed during a wash cycle in which the magnet is shut off. Titanium, which is often bound up with iron, is also removed. These are known as cryogenic magnets.

While these technologies can improve the brightness of kaolin products and sometimes reduce costs, they generally present additional costs in the form of energy, chemicals, and other supplies.

Primary author: Murray Lines

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