Bleaching clay is also called “bentonite”, “bleaching earth”, dominated by smectite group minerals. Common minerals include feldspar, gypsum, calcite, quartz and the incomplete decomposition of volcano tuff material. General pink, white, yellowish, grayish green color. The appearance of colloidal, low hardness, immersed in water to swell, no plastic, low refractoriness. Often the tuff or volcano rock in sea water or groundwater, by weathering in alkaline medium (pH=7-8.5) environment of deposition. Because it has strong absorbency and water swelling, so use in petrochemical fields, such as used in petroleum, oil, sugar, wine making, paper making, textile and other industries as a purifying agent and bleaching agent.
Bleaching clay mineral filter is always a tricky and long-term unsolved problems. Slurry by ultrafine grinding, grading and bleaching, must pay the economic price. If the filtering problem can not be solved well, not only directly affect the enterprise efficiency, waste of mineral resources, but also polluted water and environment phenomenon is very serious
Clay is mainly composed of aluminous rocks, such as feldspar, pegmatite granite, porphyry, gneiss through long-term weathering, and often through the water transport and deposition, is a variety of fine mineral mixed body, its main chemical composition is SiO2, Al2O3 and crystal water. With the geological formation conditions are different, also contain a small amount of alkali metal oxide, alkaline earth metal oxide and metal oxides.
Most of the literature on clay will start to define or clay to some professional terminology to explain, this is very necessary, because the varieties and usage of clay is indeed much. Often the clay was classified according to Mineralogy, geology, chemical composition, physical properties of the cause or industrial purposes.
There are 3 ways: 1. The formation of clay minerals is related to weathering. Types and medium weathered rock conditions such as water, climate, landform, vegetation and time factors determine the mineral species and save or not. Hydrothermal and hot spring water in rock, can form the clay mineral alteration zone. ③ by sedimentation, diagenesis mineral formation clay. In modern or ancient sediments can sometimes be formed with industrial significance of kaolin, bentonite, palygorskite, sepiolite clay and clay rock.
Use of kaolin is mainly used for ceramic raw materials, papermaking filler and coating; mainly consisting of montmorillonite bentonite used as drilling mud, binder catalyst oil refining and bleaching agent, iron ore pellet and casting sand binder; palygorskite and sepiolite clay is the manufacture of salt mud quality raw materials, grease decoloring agent and absorbent.