Talc, Montana

The composition of talc varies depending on its source. The most important factor is the amount of tremolite present. In the USA, for instance, Montana talcs are considered to be asbestos and tremolite free. The California plate-like talcs contain minor amounts of tremolite (less than 3%), whereas hard talcs contain between 5 to 25% tremolite. Some industrial talcs mined in upper New York State contain 25 to 50% tremolite. The other important component in its composition is water which is chemically combined in the magnesium oxide or brucite layer. Figure 2.62 shows the molecular structure of talc. Talc may lose this water only on... 

Nicron. Montana Talc] Pla talc low ofl absoiption filler for poinis, idasti sols, and coatings. 

SteriLine. [Montana Talc] Platy talcs high puriQr tates meeting USP, CTFA, and Eurcqiean Pharmacopeia specs. for cosmetics, antiperspirants, dusting powders, pharmaceutical excipients. 

Chem. Descrip. High purity Montana talc Chem. Analysis SIO (60%), MgO (33%), AljOs (1%), moisture (0.5%) CAS 14807-96-6 EINECS/ELINCS 238-877-9 Uses Filler for solv.- and water-based paInts/coatIngs, semigloss paints, OEM/speclalty areas, rigid vinyl, and polyolefins Properties Powd. 0.8 p median particle size fineness (Hegman) 6.5 sp.gr. 2.8 dens. 22 Ib/ft (tapped) bulk dens. 6.4 Ib/frf bulking value... 

The type of further processing depends on the purity of the ore (dry versus wet processing). Pure Montana talc can be dry processed. The fourth and fifth steps in talc manufacturing involve grinding and classification. It is in these areas that most advances have been made in the past 25 years as consumers have realized the effectiveness of fine particles (large surface area) over coarser ones [6j. Only for more demanding applications such as in the pharmaceutical industry is further purification necessary. 

For steatite bodies used in electrical insulating apphcations, pure talc along with about 10% plastic kaolin and 10% barium carbonate is fired at cone 12-13 to form low loss bodies. Low calcium and alkah metal levels are critical, so only high purity Montana talc is used. Consistency is also critical, since... 

Montana talc - Montana talc is known for its naturally high purity and brightness. The principal impurities are small amounts of chlorite, dolomite, and magnesite. The high natural purity makes it possible to produce products for a wide range of uses with little or no beneficiation. 

Talc is insoluble in water, organie solvents, cold acids and dilute alkalis. It may contain bacteria, but it can be sterilized by dry heat at 160°C for not less than 1 horn, or by exposure to ethylene oxide. Depending on the source from which it is mined, talc displays different surface charaeteristics. The Montana talcs are hydrophobic in nature, whereas the California talcs are predominantly hydrophilie. 

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