tailieunhanh - Applied Clay Mineralogy Phần 7

Cao lanh được sử dụng trong y học và dược phẩm phải được tự do của kim loại độc hại, grit, và được khử trùng để loại bỏ vi sinh vật gây bệnh. | 106 Applied Clay Mineralogy kaolin is used as a diluent. As described above kaolin is treated with selected pesticides and or insecticides and is sprayed as a slurry onto fruit trees and other garden products. Many pesticides are in concentrated form which can have a harmful effect on plants and must be diluted for effective and economical application. . Medicines and Pharmaceuticals Kaolins are used as an absorptive for gastro-intestinal disorders as a tablet or capsule diluent as a suspending agent in poultices and for dusting in surgical operations Russel 1988 . As an absorptive clays absorb toxins and harmful bacteria in addition to forming a soothing protective coating on inflamed mucous membrane in the digestive tract Goodman and Gilman 1955 . Kaolins used in medicines and pharmaceuticals must be free of toxic metals grit and be sterilized to remove pathogenic micro-organisms. Kaolin is used as a suspending agent for pectins in the well-known product kaopectate. Kaolin is also commonly used as a diluent in capsules and tablets. In tablets it aids in making the tablet strong and dense when the tablet is compressed. . Pencil Leads Fine particle kaolin is used along with a minor amount of bentonite to bond graphite in pencil leads Murray 1961 . The graphite and plastic kaolin are mixed and extruded to form the pencil lead. The lead is dried and fired to produce a strong pencil lead. The hardness of the lead 2H 3 H 5 H etc. is controlled by the percentage of clay in the lead. A soft lead 2 H contains less clay than a harder 5 H lead. . Plaster Kaolins are used in plaster as a white colorant to disperse and improve the uniformity of the plaster to increase the percent solids and reduce the water content and to improve the workability and flowability. Fine particle size kaolin is preferred for this use. . Polishing Compounds Ultra-fine calcined kaolin is used in many polishing compounds. The particle size is 100 finer than 3 mm and 90 finer than