Kaolin is a general term for a group of clay minerals. Its basic composition is the kaolinite group and halloysite group. It is mainly composed of kaolinite and halloysite, with a content of more than 90%, followed by hydromica. It also contains pyrite, limonite, anatase, quartz, chalcedony, alum, and sometimes a small amount of organic matter. Due to its excellent processability such as plasticity, cohesiveness, sinterability, and fire resistance, kaolin is widely used in ceramics, paper, rubber, plastics, and refractory industries. There are three main types of kaolin deposits genesis: weathering, sedimentary, and hydrothermal alterations.
The processing of kaolin ore depends on the nature of the ore and the end use of the product. There are two processes used in industrial production: dry process and wet process. Usually, hard kaolin is produced by the dry process, while soft kaolin is produced by the wet process.
Characteristics of Kaolin Mineral Processing Technology
The comprehensive kaolin mineral processing technology in the country has the following characteristics:
The ore mined from the mine is coarsely selected on-site, and a large amount of tailings are discarded in the mine. This not only solves the filling of the goaf but also reduces the stockpiling and transportation of the ore in the ore dressing plant. The concentrate of the coarse selection plant is used. Pipeline transportation is generally used between mines and selected plants. Since 1939, kaolin slurry has been transported by a pipeline. High-concentration pulping is used, and a dispersing agent is added to the pulp during the sorting process. A flocculating agent is added during the dehydration process, and the filter press or vacuum filter product can be sold as a product without drying.
In addition to the hydrocyclone classification, the mineral processing operation also uses a centrifugal classifier, a sand mill, a high-gradient magnetic separator, and a flotation machine to improve product fineness and reduce impurities such as iron, titanium, and sulfur. The chemical bleaching process is commonly used in major kaolin producing countries such as the United States, the United Kingdom, and the former Soviet Union to produce high-whiteness kaolin products, but at a higher cost.
The products on the Gaoling are sold in bulk, coarse powder, fine powder, and paste form. The manufacturer supplies different products according to the requirements of the users. There are many types of drying equipment for the products, but the most commonly used is spray drying because the cost is relatively low.
The concentrator not only has a large production capacity but also has many varieties and is a standardized product. It can meet the needs of different users. The China Kaolin Company has four categories and 34 varieties. These products are widely used in paper fillers and coatings, ceramic industry raw materials, rubber and plastic fillers and reinforcing agents, white cement oil felts, roofing coatings and waterproofing agent ingredients, fiberglass ingredients, ink pigments, cosmetics and soaps. Fillers, carriers of pesticides and fertilizers, binders for abrasive materials, synthetic molecular sieves, petroleum catalysts, atomic energy reactors, etc.