Kaolinite is a mineral belonging to the group of aluminosilicates. It is commonly referred to as “China Clay” because it was first discovered at Kao-Lin, in China. The term kaolin is used to describe a group of relatively common clay minerals dominated by kaolinite and derived primarily from the alteration of alkali feldspar and micas. Kaolin is an industrial mineral used primarily as an inert filler and customers combine it with other raw materials in a wide variety of applications. Kaolin is a white, soft, plastic clay mainly composed of fine-grained plate-like particles. Kaolin is formed when the anhydrous aluminium silicates which are found in feldspar rich rocks, like granite, are altered by weathering or hydrothermal processes. The process which converted the hard granite into the soft matrix found in kaolin pits is known as “kaolinisation”. The quartz and mica of the granite remain relatively unchanged whilst the feldspar is transformed into kaolinite. Smectite may also form in small quantities in some deposits. The refining and processing of the fine fraction of the kaolinised granite yields predominantly kaolinite with minor amounts of mica, feldspar, traces of quartz and, depending on the origin, organic substances and/or heavy minerals.
Individual kaolin’s vary in many physical aspects, which in turn influence their end use. Of particular commercial interest is the degree of crystallinity which influences the brightness, whiteness, opacity, gloss, film strength, and viscosity.
Kaolin is part of our natural world. Its uses are multiple and diversified. Kaolin’s whiteness and plasticity make it extremely suitable for its extensive use as a filler, extender, ceramic raw material and pigment. It is also an important raw material to refractories, and to catalyst, cement and fibre glass industries.
Kaolin is used in many applications. It is a unique industrial mineral, which remains chemically inert over a relatively wide pH range and it offers excellent covering when used as a pigment or extender in coated films and filling applications. In addition, it is soft and non-abrasive and has a low conductivity of heat and electricity.
The two largest applications of kaolin are the coating of paper to hide the pulp strands and the production of high-grade ceramic products. It is also used in many other industrial processes.
Mature established markets often utilise kaolin in ceramics for high quality porcelain or as catalysts for Fluid Catalytic Cracking. New and emerging markets are known to employ kaolin, often in high purity alumina production and in creating halloysite nanotube technologies. In addition, kaolin is use in hydrogen storage and transport, batteries and super-capacitors, water purification, carbon dioxide capture – storage and conversion to fuel, medical delivery of drugs, construction– delivery of biocides, agriculture–delivery of pesticides and fertilisers, as well as polymers and coatings for reinforcement and fire-retardancy. A booming construction industry in the Asia-Pacific region is leading an increase in the demand for ceramic products, which in turn is expected to boost the growth of the halloysite kaolin market. Chinese processors have significant demand for feedstock to process through their wet processing facilities but have struggled to find a product with adequate quality and reliability to ensure a premium end-use product and thus are searching for a high-grade supply to feedthrough their facilities. Due to the decline in Chinese supply, the global halloysite kaolin market is characterised by a limited number of players. Small-scale producers in Thailand and Brazil produce for their respective domestic markets, Chinese companies look for a halloysite grade of ~20%. China has traditionally supplied the market in this sector; however, mines have been closing due to government crackdowns on environmentally-damaging mines. There are about 15-20 major Chinese players in this space who are vertically integrated producers (with both their own mines and processing facilities), however the quality of product is very low. Additionally, there are about six large processors who do not have a mine and are searching for reliable direct shipping ore product. The Mt Marshall Project is potentially a high-grade Kaolin deposit located on private land with granted tenure. Transport logistics are in place with significant available rail capacity to Fremantle Port.
- Ceramic Applications
- Paper Coating
- Bricks, pavers, Roof tiles