Separation Method Of Kaolin

(1) In order to separate non clay minerals such as quartz, feldspar, mica, iron minerals, titanium minerals, and organic matter from kaolin and produce kaolin products that can meet the needs of various industrial fields, in addition to using gravity separation, flotation, magnetic separation, etc. to purify and remove impurities from kaolin, sometimes deep processing methods such as chemical bleaching, ultrafine peeling, calcination, and surface modification are also used to treat kaolin. The mineral processing of kaolin can be divided into two processes: dry process and wet process.

(2) The dry method generally involves crushing the extracted raw ore through a crusher to around 25mm and feeding it into a cage crusher to reduce the particle size to around 6mm. The crushed ore is further ground by a blowing Raymond mill equipped with a centrifugal separator and cyclone dust collector. This process can remove most of the sand and gravel, and is suitable for processing ores with high whiteness, low sand and gravel content, and suitable particle size distribution. Dry processing has low production costs and products are usually used as low-cost fillers in industries such as rubber, plastics, and paper.

(3) The wet processing technology generally involves crushing the raw ore, followed by pulping, sand removal, cyclone classification, peeling, centrifuge classification, magnetic separation (or bleaching), concentration, pressure filtration, and drying. The resulting product can be used for ceramics or papermaking coatings. If preparing filler grade or paper-making coating grade kaolin, it is necessary to increase the calcination process, including raw ore crushing, pulping, cyclone classification, peeling, centrifugal classification, concentration, pressure filtration, internal steam drying, calcination, depolymerization, etc. [4]

(4) The calcination method is a widely used method for producing special kaolin products. It has four calcination temperature ranges: 500-700 ℃, 925 ℃, 1000 ℃, and 1400 ℃. The application range of the product obtained by calcination at different temperatures also varies. Calcined kaolin, which only removes hydroxyl groups, is used as a filler for cable plastics and rubber sealing rings; Kaolin calcined at 1000 ℃ can replace TiO2 and be used as a paper filler; Kaolin, which has been calcined at 1300~1525 ℃, can be used as a filler for refractory products and as an inner lining for optical glass crucibles.