Kaolin is the name given to a variety of hydrous aluminum silicate clays. The name is believed to originate from the Chinese “kao-ling”, meaning “high ridge” that referred to an area in southeastern China where the clay was originally discovered and used. Kaolin, or “china clay”, as it is also called, has been used for ceramics for thousands of years.
As the name implies, kaolin is composed primarily of kaolinite (>90%), mica and quartz (<10%, as impurities). Kaolin clay comes from the hydrothermal alteration of feldspar found in granite and pegmatite deposits. It can be a “primary” kaolin (hydrothermally altered in place) or” secondary” kaolin (hydrothermally altered, transported by water and deposited as sediment). The latter is the case in most of the commercial kaolin clays produced in the US today. Primary kaolin is usually, but not always coarse-grained with some small amount of residual potassic alkali oxides. Secondary kaolin is typically finer-grained than primary kaolin with little or no residual alkali, although secondary kaolin can be relatively coarse-grained or fine-grained.
Kaolin clays are found in many regions of the world, with the largest and highest quality deposits occurring in the United States, Europe (Germany, France and England) and Brazil. In the US, the largest and purest kaolin deposits are found in Georgia, although kaolin clay is mined in South Carolina, Alabama, Texas, and California, in addition to Georgia.
Kaolin is processed for industrial use by either wet or dry systems, depending on the application requirements. For paper, pigment and filler applications, the raw kaolin clay is usually slurried and ground in wet mills, and can be further processed by centrifuging, magnetic separation, bleaching and calcining to increase brightness. For other filler, ceramic and fiber glass applications, kaolin is dry processed using roller or hammer mills and air classification.
Old Hickory Clay Company dry processes its Wilco kaolin products for ceramics and specialty filler applications at its facility in McIntyre (Wilkinson County), GA. The company offers Wilco LPC, a relatively coarse-grained kaolin clay designed for drain and pressure casting applications, and Wilco UPF, a fine grained kaolin clay for use in general ceramic and specialty filler applications. Both Wilco kaolin grades are available in shredded (~20% moisture), semi dried (~10-18% moisture) and air-floated (~3% moisture) forms to meet the needs of our customers. Old Hickory has access to many raw kaolin clays for developing specific solutions to our clients’ most demanding manufacturing applications.
Wilco kaolin grades are shipped in bulk and in packages via rail and truck to consumers all over North America and Mexico, and in packages to Europe, Central America and South America. Old Hickory has the experience and expertise with logistics to ship kaolin clay anywhere in the world.
Technical support is important to successful marketing and sales of kaolin clays to the consuming industries. Old Hickory Clay has over 95 years of experience in providing customer support, and the technical team uses the latest technology in characterization, analysis and production control of our high quality clay products for our clients. We provide kaolin clay “solutions” to our clients’ toughest problems.