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Kaolin is a soft, white mineral mainly composed of course- to fine-grained, plate-like aluminum silicate particles. Individual kaolin clays vary in many physical aspects, which in turn influence their end uses.
Kaolin has been used for centuries. The ancient Chinese used it in the manufacturing of pottery and gave kaolin its original name, “kaoling” (meaning “high ridge”). It was not until the 20th century that many of today’s uses for kaolin came into prominence.
Kaolin Beneficiation
Kaolin beneficiation, or the process of improving the chemical and/or physical properties of crude kaolin, includes many, often complex steps. Some of these steps include:
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Chemical and mechanical dispersion of raw ore
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Screening or sieving to remove sand, mica.
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Reverse flotation to remove discoloring impurities
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Selective flocculation or reverse selective flocculation to remove discoloring impurities
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High gradient magnetic separation to remove discoloring impurities
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Centrifugation using solid bowl and/or disc nozzle centrifuges to control particle size distribution
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Wet attrition milling to delaminate platy kaolins thereby producing high aspect ratio products
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Chemical flocculation and leaching processes to solubulize iron and prepare kaolin slurries for subsequent dewatering
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Dewatering processes including the use of hydroseparators, rotary vacuum filters, membrane filters, pressure filters.
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Use of high temperature processing equipment including spray dryers, rotary dryers, rotary and vertical calciners.
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Use of bulk loading and packaging equipment including screw conveyors, pneumatic conveyors, rotary valves, large and small bagging systems.
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Dry size reduction equipment including cage mills, roller mills and high speed pulverizers
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High speed slurry dispersion equipment including dispersers and rotor stator mixers of various types
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