Method for separating kaolin
For the separation of quartz, feldspar, kaolin, iron ore, mica titanium minerals and other non clay minerals and organic matter production, which can meet the demand of various industries kaolin products, in addition to the use of gravity separation, flotation and magnetic separation of kaolin was purifying, sometimes using chemical bleaching and stripping, ultra-fine calcined surface modification processing method for processing of kaolin. The processing of kaolin is divided into two processes, dry process and wet process. </p><p> (1) dry process, usually the ore will be broken through the crusher to about 25mm, to the cage crusher, the particle size reduced to about 6mm. The crushed ore is further ground by a blown Raymond Mill equipped with a centrifuge and cyclone dust collector. The process can remove most of the sand and gravel, and is suitable for processing ores with high whiteness, low sand content and suitable particle size distribution. Dry processing is of low cost and is usually used as a low filler for rubber, plastics, and paper making industries.
In order to prepare coating grade kaolin products, stripping of thicker layered kaolin must be made into thin sheets. Stripping methods include wet grinding, extrusion and chemical soaking. The wet grinding method will be made about 40% gas solid kaolin slurry, adding dispersant, adding grinding medium (such as quartz sand, porcelain beads, glass beads, nylon polyethylene beads) grinding machine, grinding and sieving after a certain period of time, the precipitation is. Extrusion method will be kaolin pulp sent to the high-pressure pulp mixer, the high-pressure paste pressure to 20 ~ 35Mpa, and then sprayed by the nozzle, due to sudden pressure drop, so that kaolin crystal laminated loose". High speed slurry ejected into the impeller, suddenly change the direction of movement, so that loose crystal lamination peeling. The chemical immersion method using urea solution soaked kaolin powder, and heated to 30 to 80 DEG C, adding a small amount of dispersant, the kaolin fully dispersed, high-speed stirring, so that the crystal layer peeling. Benzidine and acetamide can also be used instead of urea. The neutral water solution of AlCl3 is mixed with Na2SiO3 according to the ratio of 1 to 0.75 to 1 to 5 to produce precipitation.
Calcination is a widely used method for producing special kaolin products. It has 4 calcination temperature ranges: 500~700, 925, 1000, 1400. Calcined at different temperatures, the application scope of the product is different, only the removal of hydroxyl groups of calcined kaolin used as cable plastic and rubber sealing ring filler; after 1000 calcined kaolin can be used as paper filler; Tio2, after 1300 ~ 1525 calcined kaolin used as refractory filler, optical glass crucible lining etc..
The wet process will be broken through the ore pulp, in addition, sand, cyclone, stripping, centrifuge classification, magnetic separation (or bleach), concentration, filtration and drying can be obtained, such products can be used in ceramic or paper coating. If the preparation of filler grade or paper coating kaolin to increase the calcination process, namely ore crushing, pulping, cyclone, stripping, centrifugal grading, concentration, pressure filtration, steam drying, calcination, depolymerization etc..
