Synthesis method of kaolin

Synthesis method of kaolin

(1) In order to separate non clay minerals and organic matter such as quartz, feldspar, mica, iron minerals, titanium minerals, and produce kaolin products, in addition to gravity separation, flotation, and magnetic separation purification, sometimes deep processing methods such as chemical bleaching, ultrafine peeling, calcination, and surface modification are used. The beneficiation and processing of kaolin can be divided into dry and wet processes.

(1) The dry method usually uses a crusher to crush the extracted raw ore to around 25mm and reduce the particle size to around 6mm. The crushed ore is further ground by a blower Raymond equipped with a centrifugal separator and cyclone dust collector. This process can remove most of the sand and is suitable for processing ores with high whiteness, low sand content and proper particle size distribution. Dry processing has low production costs, and products are typically used as low-cost fillers in industries such as rubber, plastics, and paper.

(2) Wet processing technology generally crushes the raw ore and can be used for ceramics or paper coatings. If preparing filler grade or paper coating grade kaolin, it is necessary to increase the calcination process, such as raw ore crushing, ramming, cyclone classification, stripping, centrifugal classification, concentration, pressure filtration, internal steam drying, calcination, depolymerization, etc.

The calcination method is a widely used product ranging from 700 ℃, 925 ℃, 1000 ℃, and 1400 ℃. The application range of products varies with calcination at different temperatures. Calcined kaolin only removes hydroxyl groups as fillers for cable plastic and rubber sealing rings; Kaolin calcined at 10000 ℃ is a replaceable TiO2 used as a paper filler; Kaolin calcined at 13000~1525 ℃ can be used as filler for refractory products, lining for optical glass crucibles, etc.

(4) The peeling method requires the kaolin to be peeled into thin slices. The peeling method includes wet grinding, extrusion, and chemical soaking After adding dispersants, add grinding media (such as quartz sand, ceramic beads, glass beads, nylon polyethylene beads, etc.) to the grinding machine, Grind for a period of time, screen, and then precipitate for classification High pressure homogenization of~35Mpa, followed by nozzle spray. Due to a sudden decrease in pressure, the crystal layer of kaolin becomes loose. The high-speed jet of slurry is sprayed onto the impeller, suddenly changing the direction of movement and peeling off the loose crystal layer Soaking agent~80 ℃, add a small amount of dispersant to completely disperse the kaolin, stir at high speed to peel off the crystal layer. Urea can also be replaced by Benzidine and acetamide. Mix AlCl neutral aqueous solution with Na2SiO3 in a ratio of 1:0.75 to 1:5 to produce precipitation. Dry at ℃ to obtain Al2O3 · 2SiO2 · 2H2O.

(5) Grind the kaolin fine, wash away the sand, treat it with Mineral acid, wash it to near neutral, and dehydrate it above 3300 ℃