MICA method

In the symmetric, three-layer interferometer, only even-order fringes are sensitive to refractive index and it is possible to obtain spectral infonnation of the confined film by comparison of the difierent intensities of odd-and even-order fringes. The absorption spectmm of tliin dye layers between mica was investigated by Muller and Machtle [M, M] using this method. 

Instead of an absorbing dye layer between the mica. Levins et al [57] used thin metallic films and developed a method for FECO analysis using an extended spectral range. 

Protems can be physisorbed or covalently attached to mica. Another method is to innnobilise and orient them by specific binding to receptor-fiinctionalized planar lipid bilayers supported on the mica sheets [15]. These surfaces are then brought into contact in an aqueous electrolyte solution, while the pH and the ionic strength are varied. Corresponding variations in the force-versus-distance curve allow conclusions about protein confomiation and interaction to be drawn [99]. The local electrostatic potential of protein-covered surfaces can hence be detemiined with an accuracy of 5 mV. 

Flake Mica. Flake mica is mined from weathered and hard rock pegmatites, granodiorite, and schist and gneiss by conventional open-pit methods. In soft, residual material, dozers, shovels, scrapers, and front-end loaders are used to mine the ore. Often kaolin, quartz, and feldspar are recovered along with the mica (see also Clays Silicon compounds). 

The general pieces of equipment used in grinding flake mica or mica concentrate into saleable mica products are hammer mills of various types, fluid energy mills, Chaser or Muller mills for wet grinding, and Raymond or WiUiams high side roUer mills. Another method is being developed, called a Duncan mill (f. M. Huber, Inc.), that is similar in many respects to an attrition mill. AH of these mills are used in conjunction with sieves, and all but some types of hammer mills incorporate air classifiers as a part of the circuit. 

Oil Absorption. The Gardner mb-out (ASTM D281) method is used for this evaluation. A 5-g sample of mica is placed on a smooth glass plate, and linseed oil is added by drops. The mica is constantiy mixed while the oil is being added. The end point is reached when the mica becomes saturated with oil. The amount of oil per 45.4 kg of mica is calculated as follows ... 

The grit content of coarse mica is deterrnined by the vanning method. A 25-g sample of dry mica is placed on a vanning plaque or a 21.6 x 28-cm... 

General References Adair, New Method for Recovery of Flake Mica, ... 

The micas, as a class, are difficult to grind to a fine powder one exception is disintegrated schist, in which the mica occurs in minute flakes. For diy grinmng, hammer mills equipped with an air-transport system are generally used. Maintenance is often high. It has been established that the method of milling has a definite effect on the par-... 

Table 18. Effect of molding method on mechanical properties of mica-filled thermoplastics (Vf = 0.5) [375]...

The molecular structure of a Cgo-Pst hyperbranched polymer can be described as in Fig. 20. Cgo-Pst hyperbranched polymer molecules were transferred onto mica chips by the vertical dipping method of L-B him techniques as introduced above. 

It has been shown that surface-modihed C5Q-Pst polymer was synthesized and was transferred onto mica chips by using the vertical dipping method of L-B film techniques. Though the surface was scanned many times, only a small amount of transfer could be found on the surface of the L-B Hlms. L-B films of C5Q-Pst polymer, even with only one layer, showed good microtribological performance. The topography and the order of the hlms are the most important factors influencing the microscale friction and wear. 

This mbber is very tacky in nature and contains acrylic group, which makes it polar in nature. Nanocomposites have been prepared based on this elastomer with a wide range of nanohllers. Layered silicates [53-55] have been used for this preparation. Sol-gel method [56,57], in situ polymerization [58], and nanocomposites based on different clays like bentonite [59] and mica [60] have been described. The mechanical, rheological, and morphological behaviors have been investigated thoroughly. 

Figure 6 shows droplets of KOH solution on mica produced by similar methods. In both cases the drop profiles are very close to a spherical cap. In Figure 7 we have plotted the effective contact angle as a function of droplet height. The deviation from the macroscopic contact angle with decreasing droplet volume can clearly be seen. 

A fluid loss additive is described that consists of granular starch composition and fine particulate mica [337]. An application comprises a fracturing fluid containing this additive. A method of fracturing a subterranean formation penetrated by a borehole comprises injecting into the borehole and into contact with the formation, at a rate and pressure sufficient to fracture the formation, a fracturing fluid containing the additive in an amount sufficient to provide fluid loss control. 

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. 

K being the leaf-spring constant) and by starting measurements with the surfaces far apart, where F(D) = 0, force profiles may be determined. The method also allows the measurement of the mean refractive index n(D) of the medium between the surfaces (9), and from this the amount r of adsorbed species per unit area of mica may be evaluated. Finally the mean radius of curvature R of the cylindrically curved mica surfaces near the contact area may also be calculated from the shape of the interference fringes. 

Resch, R. Prohaska, T. Friedbacher, G. Grasserbauer, M. Kanniainen, T. Lindroos, S. Leskela, M. Niinisto, L. Broekaert, J. A. C. 1998. In-situ investigation of ZnS deposition on mica by successive ionic layer adsorption and reaction method as studied with atomic force microscopy. Fresenius J. Anal. Chem. 353 772-777. 

Figure 8.11 Illustration of Mauguin twisted nematic cell, reported in 1911. Substrates are thin mica plates, which are uniaxial with their optic axis parallel to plane of plates. Apparently, uniaxial crystal stmcture of mica produces strong azimuthal anchoring of nematic LCs of Lehmann, such that director is parallel (or perpendicular) to optic axis of mica sheets at both surfaces. Mauguin showed that method of Poincard could be used to explain optics of system if it was assumed that LC sample created layer of material with uniformly rotating optic axis in twisted cells.

In our initial use of VIRS methods, we have chosen a diverse set of projects. These include epithermal-style precious metal mineralization (eastern and central Newfoundland), mesothermal gold mineralization (Central Newfoundland), syngenetic VMS mineralization and related alteration (Central Newfoundland), porphyry-style Mo-Cu mineralization (southern Newfoundland) and uranium mineralization in the Central Mineral Belt of Labrador. Space does not permit detailed discussion of results, but in all cases we were able to recognize distinctive alteration species and document their distribution. In some cases, results provided surprises, eg., the recognition of topaz in quartz-alunite alteration and possible Li-rich micas in VMS alteration influenced by magmatic fluids. In some cases, the resolution of species in mixed assemblages proved to be difficult, but the overall spectral patterns could still be used to discriminate alteration facies and demonstrate their superposition. 

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