Production of ball clay in the UK dates back to the early 17th century and became important in the late 17th and early 18th century when the Staffordshire potters recognised its attributes. Figure 23: Primary shredding of the Ball Clay. For general descriptive purposes a ball clay can therefore be regarded as an idealised ternary system consisting of kaolinite, mica and quartz. Production in 1993 was put at 12,000 tonnes per month, mainly destined for the São Paulo market due to being adjacent to the main BR101 highway. To be able to estimate the probable fired properties of a given ball clay, it is not enough merely to know its chemical composition. Kentucky-Tennessee operates from active mines in Kentucky, Tennessee and Mississippi and has four processing plants at Mayfield, Kentucky; Gleason, Tennessee; Whitlock Tennessee; and Sledge, Mississippi. Alternatively the name was derived from the digging implement formerly used called a tubal. Particle distribution curves (Fig. The north Devon clays are all of the lean stoneware type but can be divided into two types. The sediments filling the axial trough consist largely of silts, sands and gravels, with only subordinate brown clays and lignites. There has also been an increase in the amount of ball clay consumed in the fiberglass industry and also in insulating fireboard as the amount of asbestos used decreases. For the sanitaryware market some products are refined to remove impurities and these are sold in both slurried and dried forms. Demand from the domestic floor tile sector also weakened due, principally, to increased imports, especially from Italy. Extraction involves excavators and dump trucks to selectively remove individual grades of clay to storage and blending facilities. Therefore a continuous recording of each borehole can be made (Fig. All testing takes place on a routine basis in the production control laboratories situated in each of the three production areas. The north Devon clays fire to a brightness similar to that of the leaner south Devon clays. 5. A large number of grades of ball clay are prepared on the basis of their fired colour - white-light grey, light grey-light cream, yellow and light red-dark red. In addition, certain of the seams contain an interstratified clay mineral, and colloidal carbonaceous matter. The weathering process converted all the chlorite and some illite to a disordered kaolinite. A summary of the Plastic Clays is shown in Table XIII along with kaolinitic clays from elsewhere in Germany and plastic clays from the small operation of Pornon & Cie in the Allier region of France (40,000 tpa). Ball clays are sold directly from the mine without processing, other than the air-drying which may occur under favourable circumstances. Very little lignite occurs in the clay beds of the Petrockstow basin, but in the West Marland Beds there is one seam of black lignitic clay. 25). WBB Pacific Clays have a joint venture in Guangdong Province, China, in which the Division has invested through Clayorient in Hong Kong, has not been as successful as planned owing to the slow acceptance in the region of the particular refined clays produced by Xiangshan. This group includes aluminum silicates of soda, potassium, or lime. Steps in the Ball clay processing are. In this article we tried to cover as much as possible about ball clay, we know that nothing is perfect everything can be improved further so if you feel that we missed something that you like to add in this article please leave your comment below. 17 illustrates typical ball clay deflocculation curves of Type A and Type B referred to in Table VI. Apart from those samples containing much free quartz, plasticity and modulus are similar to the south Devon range of ball clays. Settling. Green Modulus of Rupture: 65 Kg/cm2. They are dominantly kaolinitic with low mica and quartz contents and frequently contain appreciable quantities of carbonaceous matter. Most importantly maps can be made from satellite imagery and air photographs. MPR is the third largest producer of ball clays in the Westerwald whose sales tonnage in 1994 was almost 550,000 tonnes. Particle size distributions were carried out on nine samples and the results are shown in Fig. Ball Clay is generally called Kaolin, that had been transported from the primary decomposed parent, or igneous rock which were usually granite by nature via glacial displacement making It is a secondary clay, and in this process, it not only does it gain high organic impurities and iron contaminants but the material gets ground down into a finer particle size! Gibbsite is a common constituent in these clays but appears to have little effect on their good rheological behaviour. 9. Mined ball clay typically exhibits a moisture content around 28%. 22). The second type of carbonaceous clay, containing rather less carbonaceous material, is again a strong and plastic clay which deflocculates easily and presents a good, clean, fired colour. These sediments have been dated by examining pollen samples and they range from upper Eocene to Middle Oligocene, 35 to 28 million years old [5]. These clays also contain a certain amount of carbonaceous matter which is generally helpful in producing easily deflocculated casting slips. Combustion gases from the firebox pass through an air-to-air heat exchanger to heat the drying air to a temperature of approximately 300°C (570°F). Sample for testing will be taken from different areas from the clay leap so that the result will be accurate. The clays from this area are light grey to brown, sandy to very sandy clays with very little iron staining. [5], Ball clay use in ceramic Coade stone sculpture, "History of Ball Clay - Swanage Railway", https://en.wikipedia.org/w/index.php?title=Ball_clay&oldid=964542420, Creative Commons Attribution-ShareAlike License, This page was last edited on 26 June 2020, at 03:54.
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