Commercial micas

After grinding, various forms of screening and air classification are used to produce commercial mica products. Shipments are made in 50-lb bags or bulk containers such as pneumatic trucks, rail cars, Gaylord boxes, or fabric tote bags. 

FIuorosihca.tes, Compared to the simple sUicates, these crystals have more complex chain and sheet stmctures. Examples from nature iaclude hydrous micas and amphiboles, including hornblende and nephrite jade. In glass-ceramics, fluorine replaces the hydroxyl ion fluorine is much easier to iacorporate ia glass and also makes the crystals more refractory. Eour commercial fluorosUicate glass-ceramic compositions and thek properties are Usted ia Table 2. 

The electrostatic separation method is the exclusive choice in some specific situations, for example in the cases of rutile and ilmenite deposits. These deposits generally contain minerals of similar specific gravities and similar surface properties so that processes such as flotation are unsuitable for concentration. The major application of electrostatic separation is in the processing of beach sands and alluvial deposits containing titanium minerals. Almost all the beach sand plants in the world use electrostatic separation to separate rutile and ilmenite from zircon and monazite. In this context the flowsheet given later (see Figure 2.35 A) may be referred to. Electrostatic separation is also used with regard to a number of other minerals. Some reported commercial separations include those of cassiterite from scheelite, wolframite from quartz, cassiterite from columbite, feldspar from quartz and mica, and diamond from heavy associated minerals. Electrostatic separation is also used in industrial waste recovery. 

Finally we note that our results differ from those reported by the Australian group (7), who measured F(D) between mica plates in an aqueous solution of a commercial resin of highly polydis-persed PEO. Their results indicated short- and long-time hysteret-ic effects as well as a continuous build up of adsorbed material (up to 1000 nm over 24 hrs.), and may be due to impurities in the sample they used (20). 

Titanium Dioxide - Mica (Fig. 77). The first multilayer pigments were marketed in the 1960s as Ti02-coated muscovite micas [5.193], [5.201]. Two different processes are used for coating mica in aqueous suspension on a commercial basis ... 

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