Mica Products

Franklin Industrial Minerals Muscovite Mica Products  

Kings Mountain, NC Operation Wet Ground Mica Products WG-325  

Median Size Microns 33 Aspect Ratio 10 BET Surface Area ffl2/gm 4.7 Bulk Density lbs/ft3 12 

Median Size Microns 39 Aspect Ratio 13 BET Surface Area m2/gin 4.9 Bulk Density lbs/ft3 9 

Median Size Microns 41 Aspect Ratio 14 BET Surface Area m2/gm 5.8 Bulk Density lbs/ft3 9 

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The coarse mica concentrate is either respiraled to produce a product with a grade suitable for use by wet grinding mica producers, or floated to further upgrade it for specialty high grade dry ground mica products. 

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. 

Exact si2ing of mica products coupled with surface treatment procedures have led to a greater use for wet ground mica in plastic compositions, particularly automobile bodies. These quahty products demand a high dollar value. 

Tables 4 and 5 show properties of ground mica products. For all forms of ground mica the index of refraction is 1.58 wt %, Mohs hardness is 2.5, oil absorption (Brit. Stand. 3483) is 60.75%, water solubihty (Brit. Stand. 1765) is <0.3%, the phericity factor is 0.01, and the softening point in °C is 1538. For Microni2ed and wet ground micas the brightness (green filter), pH, and apparent density in kg/m are 75, 5.2, and 160—224, respectively for dry ground mica, 66—75, 6.2, and 192—561, respectively (1).

Table 4. Particle Size Distribution of Ground Mica Products ...

Health regulations are supervised by county and state health departments. There are no known health problems caused by the mica crystal, however, most iadustrial mica products contain some free siUca particles that can cause siUcosis and some states require employees who work ia mica plants to receive an aimual x-ray. 

Suzorite Mica Products, Inc. 1475 Graham Bell Street Boucherville, Quebec J4B 6A1, Canada tel 1 514 655 2450 fax 1 514 655 9942 Suzorite Mineral Products, Inc. 1040 Crown Pointe Parkway Suite 270 Atlanta, GA 30338, USA tel 1 770 392 8664 fax 1 770 392 8670 calcium carbonate mica 49 113... 

Total mica production in the U S was about 99 000 tons in 2008, which is about one-fourth of the worldwide mine production estimated to be about 390 000 tons [27]. Countries with the highest levels of mine production, and correspondingly large estimated reserves, are the United States and Russia, followed by Finland, the Republic of Korea, France, Canada, Brazil, and India, among others. 

ZEMEX Industrial Minerals, Boucherville, Que, Canada, Technical information on Suzorite mica - products and applications (ZEMEX is acquired by Imerys). 

Suzorite Mica Products, Inc., Boucherville, Que., Canada, MSDS Suzorite Mica, September 2003. 

Aspect ratio is a very important characteristic of mica products because it has a significant effect on the increase in flexural modulus obtained with a given loading level of mica. High-aspect ratio mica produces the largest increase in flexural modulus. 

Mica products are also very stable at high temperatures. Thermogravimetric analysis shows that both muscovite and phlogopite mica are thermally stable to over 450°C, which is far above the processing temperatures for polyolefin composites. Table 14.3 lists some of the more important physical properties of mica. 

A sieving process is used to produce flake products, although all micas are, of course, flake products. This process is used with both phlogopite and muscovite mica. The D(v, 0.5) for flake mica products varies from 30 to over 1000 pm. 

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. 

Mica products are usually analyzed by screening to determine particle distributions. Specifications typically include minimum and maximum values for the amount of mica passing or retained on screens of varying mesh sizes. Another value often used for a material specification is loose bulk density. Laser particle size analysis is also being used to some extent to define mica products. One should remember that most other minerals are measured by an instrument called a sedigraph, which measures the size of particles based on their settling rate. This procedure can be used with very small low-aspect ratio minerals such as calcium carbonate, talc, silica, very small particle size mica, and aluminum trihydrate but cannot be used for analysis of most mica products. Sedigraph particle size values for very small mica products are about one-half to one-third of the values obtained by laser diffraction. 

Mica product Initial particle size D(v, 0.5) (pm) Mica size after processing, PP-CP Mica size after processing, TPO=>... 

The bulk density of mica also effects compounding rates. Higher bulk density mica products are wet out by resin much faster than low bulk density mica. This occurs because it is more difficult to remove adsorbed air from smaller particles in low bulk density fillers. 

As one might expect, increasing the amount of different mica products in polypropylene composites increases flexural modulus significantly. See Tables 14.8, 14.9, and 14.10 for the changes in flexural modulus obtained with different amounts of mica in polypropylene homopoiymer, copolymer, and thermoplastic polyolefin (TPO) formulations. Flexural modulus increases more in polypropylene homopoiymer than in the other systems. For 30 wt% loadings, the flexural... 

Effects of different loading levels of several mica products on HDT are shown in Tables 14.11,14.12, and 14.13. Increasing the amount of mica always increases HDT of the composite. The same mica products that gave the largest increases in flexural modulus also produced the highest increases in HDT. With 30 wt%... 

Flexural strength improvements with several mica products are listed in Tables 14.14, 14.15, and 14.16. Mica was much less effective in increasing flexural... 

Tables 14.17,14.18, and 14.19 show that addition of mica to polypropylene compounds has a negative effect on Izod impact properties. In each of the three resin systems, Izod impact decreases steadily with increasing amounts of mica. In homopolymer composites (Table 14.17), the largest particle size mica product, L-...

The smallest mica products give the best Izod impacts in copolymer and TPO composites. For 30 wt% filled copolymer and TPO, the Izod impact with... 

Mica products with smallest particle size, PM-325 and C-3000, provide highest flexural strength and Izod impact values. For example, C-3000 and HiMod-270 at 30 wt% loading in the copolymer give flexural strength values of 5570 and 4760 psi, respectively. Izod impact for the C-3000 composite was 3.7 versus 1.9 ft-lb/in for the HiMod-270 composite. 

Har-160 mica was modified with the various treatment chemicals in a Patterson Kelly blender to coat 1 wt% of the active treating material on the surface. Treated mica products were dried at 100°C for 2 hr before use. The two maleic anhydride modified polypropylene additives. Polybond 1001 and Polypro PC-072, were added to the composite formulation before compounding. Test specimens containing 40 wt% mica were produced by compounding in a twin-screw extruder and then injection molding. 

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