Mineral talc

The mineral talc is extremely soft (Mohs hardness = 1), has good sHp, a density of 2.7 to 2.8 g/cm, and a refractive index of 1.58. It is relatively inert and nonreactive with conventional acids and bases. It is soluble in hydroduoric acid. Although it has a pH in water of 9.0 to 9.5, talc has Lewis acid sites on its surface and at elevated temperatures is a mild catalyst for oxidation, depolymerization, and cross-linking of polymers. 

Chisso-Asahi uses a spouted bed process for the production of their coated materials (12). A 12,000 t/yr faciHty is located in Japan. The semicontinuous process consists of two batch fluid-bed coaters. A dilute polymer solution is prepared by dissolving 5% polymer and release controlling agent into a chlorinated hydrocarbon solvent such as trichloroethylene. The solution is metered into the spouted bed where it is appHed to the fertilizer core. Hot air, used to fluidize the granules, evaporates the solvent which is recovered and reintroduced into the process. Mineral talc, when used, is either slurried into the polymer solution or introduced into the fluidizing air. 

Quartz is abundant in siliceous ore, barite ore and tetsusekiei ore. Minor amounts of Mg-minerals (talc, Mg-chlorite) occur in sekko ore. Chlorite occurs in. sekko ore and it contains high amounts of Mg (Fig. 1.18). 

Figure 4.8 ((a), (b), (c), and (d)) displays, in a simplified manner, the alteration of the basic properties of homopolymer (H-PP) when modified with other comonomers (co-PP), with elastomer (impact) or with an inorganic filler mineral, talc, short or long glass fibres (SGF or LGF). 

The mineral, talc and, especially, fibreglass-filled grades are more rigid and have better behaviour and lower creep when the temperature rises. 

Mineral Talc.—A. smooth, greenish-white earth, forms the body of tinted rouges. The different colored ochres are also sometimes used as pigments for soapB. 

French White.—This is the mineral talc, or French chalk, finely levigated and bolted. It forms the basis cf the moBt harmless rouges.. Perfume is added as may be desired. 

If layers of silicon tetrahedra are condensed on both sides of a hydrargillite layer, a substance is obtained having the composition AU3i Oio(OH)t. This is the clay mineral pyrophyllite. The substance MgaSi40io(OH) obtained similarly from a brucite layer (Fig. 7-10) is the mineral talc. Both of these substances, involving the loose superposition of neutral layers, are very soft, with extreme basal cleavage.70... 

The UL temperature indexes for a variety of engineering plastics are in Table 4. Glass-filled PPS compounds exhibit a high UL temperature index, which indicates excellent retention of properties for long-term exposure to high temperature. Other fillers, eg, mineral (talc), may also be used. ... 

Lung fibrosis occurs with a buildup of fibrous material inside lung cavities. The fibers are rich in collagen, the tough, fibrous protein that gives strength to bone and connective tissue. Chronic fibrosis can result from pulmonary exposure to aluminum dust, aluminum abrasives, chromium(VI), coal dust, kaolin clay dust, ozone, phosgene, silica, and finely divided mineral talc. 

The mineral talc is a magnesium silicate [Mg3Si4O10(OH)2, density 2.5 to 2.8] that occurs as foliated to fibrous masses with a waxlike or pearly color, white to gray or green translucent to opaque. It has a distinctly greasy feel. 

This point may be illustrated by a case decided some years ago (1941) in the United States District Court for the Northern District of Illinois. The case (19) is a bit extreme but admirably illustrates the point. It had to do with a certain use of mineral talc, and for some reason, the patentee specified French talc without reservation. The defendant had substantially the same process, only he used California talc. The court held that the patentee had limited himself to French talc, and even though French talc and California talc were pretty much the same (the plaintiff said talc is talc ), there was no infringement. The case thus presents a lesson to the specification draftsman, and that explains a word that you will find so often in patent specifications—namely the word preferably. In this instance, the patentee should have specified that he preferred the use of French talc, although his invention could be practiced to a satisfactory degree if some other talc had been used. 

Soapstone or steatite is a hydrous magnesium silicate material which is composed essentially of the mineral talc, with varying quantities of carbonate minerals, chlorite, amphibole magnetite, and various other minerals (J). Steatite is very soft, easily cut, and has a somewhat greasy or soapy feel from which it derives its common name. 

The softest mineral, talc, can be used in body powder. The hardest, diamond, is used in drill bits to cut through the most dense crustal materials. Mohs scale is a relative index scale, meaning that a determination of Mohs hardness number for a mineral is based upon scratch tests. For example, gypsum (Mohs hardness number = 2) will scratch talc (Mohs hardness number = 1). Talc, however, will not scratch gypsum. Glass is assigned a Mohs hardness number of 5.5 because it will scratch apatite (Mohs hardness number = 5) but will not scratch orthoclase feldspar (Mohs hardness number = 6). 

A different clay derives from the layered mineral talc, Mg3(Si40io)(01T)2. If iron(II) and aluminum replace magnesium and silicon in varying proportions and water molecules are allowed to take up positions between the layers, the swelling clay vermiculite results. When heated, vermiculite pops like popcorn, as the steam generated by the vaporization of water between the layers puffs the flakes up into a light, fluffy material with air inclusions. Because of its porous structure, vermiculite is used for thermal insulation or as an additive to loosen soils. 

Typical apphcations of tubular presses are for fine particle dewatering including minerals, talc, and CaCOs. 

The materials shown in Table I are available in varying molecular weights and filler compositions. For molded circuit applications, the most commonly used fillers comprise chopped or milled glass fibers and/or mineral talcs. In addition to these fillers, additional components may be incorporated to impart flammability resistance or to promote electroless plating. The latter is achieved by the addition of a proprietary mineral filler which renders the polymer "catalytic" to plating. 

The oil yield and the quality of the oil can be improved by enzymes with pecti-nolytic and cellulosolytic activity (Di Giovacchino 1996). Micronised mineral talc is used in Spain for hard pastes to increase oil yields. Talc reduces oil/water emulsions and increases the recovery of free oil. However the use of coadjuvants is not in accordance with the legal definition of virgin olive oil and the oil must be obtained from the fruits solely by mechanical or other physical means. 

OTHER COMMENTS cosmetic grade talc contains more than 90% mineral talc and is free of detectable asbestos body, baby, face and after-shave powders are usually more than 50% industrial talc dusts (commercial talcs) have a varied mineral composition and may contain little or no talc found periodically as a contaminant of starch on surgical gloves. 

Clear polyolefin film with specialty mineral talc antiblocks, web tutorial (www.specialtyminerals.com). Specialty Minerals Inc. 2008 (downloaded 9 September 2008). 

In ceramics, van der Waals bonding is important in layered structures. In pyrophyllite, a layered silicate, van der Waals bonds between the oxygen ions in adjacent layers allow easy slip parallel to the layers. In the mineral talc, van der Waals bonds between the layers are even weaker than in pyrophyllite. You can cleave talc with your fingernail. 

In Figure 22.34(c) each silicate tetrahedron is linked to three others, forming an infinite sheet structure. The simplest formula of this sheet is Si20s. The mineral talc, also known as talcum powder, has the formula Mg3(Si20s)2(0H)2 and is based on this sheet structure. The Mg and OH ions lie between the silicate sheets. The slippery feel of talcum powder is due to the silicate sheets sliding relative to one another. 

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