By far the largest use of mica, both quantitative and application wise, is in the form of Ground Mica. It is prepared from grinding and breaking of mica scrap or waste namely by Dry Ground process. The production is economically carried out in high speed rotary hammer mills or pulverisers transforming into mica flakes and mica powders of different particle sizes. Meticulous care and precaution is taken to avoid deterioration of its natural brilliance, colour and properties. By virtue of its outstanding characteristics and exceptional values, Ground Mica have shown phenomenal growth rendering extensive usage in many diversified industries, in certain spheres as vital and as significant as one could well imagine.
Some major applications of Ground Mica may be illustrated as :
For Pearlescent Pigments
Mica Flakes is indispensably used in the manufacture of pearlescent pigments (pearl luster pigments) which consists of natural mica flakes coated with titanium dioxide and/or iron oxide. They possess high reflective and refractive index imparting natural pearl-like luster and magical gloss with abundant fascinating colours and enticing appearance. The unique characteristics makes it most distinctive and deeply promising in the present age. Pearlescent pigments are applied to numerous industries like paint, plastic, coating, printing ink, leather, cosmetic, dyeing, ceramic, rubber and paper.
For Wet Ground Mica Powder
Substantial quantities of Mica Flakes are processed for producing wet ground mica powder. The mica is milled with technique to preserve the structure and the sheen or luster of mica platelets without altering its natural properties. The wet grinded mica product is characterised by high quality, good purity, brilliant whiteness, large diameter-thickness ratio, regular shape and smooth surface. In addition, the product is resistant to heat, electricity and chemicals. It is widely used in such fields as pearlescent pigment, plastic, paint, cosmetic, coating, lubricant, rubber, etc. Compared to other materials, the wet ground mica powder emerges as an excellent performer.
For Oil Well Drilling
Mica Flakes are effectively used in water-based oil well drilling operations as a mud additive chemical to prevent loss of circulation and seepage in loose formations. Mica is specially added to overcome the lost circulation zones. The platy structure of mica facilitates the overlapping of particles to form a tight layer or wall and acts as a sealant that bridges the openings. Mica-mixed drilling mud helps to seal porous sections of the drill hole and contributes to regain circulation keeping the solids in suspension. Generally three grades of Mica Flakes (Coarse, Medium and Fine) are normally used for specific purposes.
For Decoration and Ornamental Display
High quality white Mica Flakes are used for bright and artificial snow impression. In addition to being beautiful, mica is non-toxic, tough, chemically inert, water resistant, fire-proof and transparent. As a decorative material to produce shimmering and glittering effects, it is used by christmas tree flockers, candle makers, floral designers, scrap bookers, wedding designers, artists, crafters and many more. It is also used to adorn and prettify wall papers, fancy papers, greeting cards and various novelties.
For Welding Electrodes
Mica Powder is well recognized for use in the manufacture of welding electrodes as a flux coating on the metal wire. Mica is added to the flux with which welding electrodes are coated as arc stabilizers, weld pool protectors, fluxing agents, slag modifiers, binders, extrusion agents and pigments. Potassium also facilitates re-ignition of the welding rods after interruptions to the current. The Mica coating provides two distinct types of protection. Firstly, it serves in forming a fusible slag and a good seal at the fusion zone of the arc. Secondly, it resists the action of heat, gaseous and other surrounding atmospheric oxidation. In fact, it is the nature of mica coating that largely determines the quality of welding electrodes.
For Gypsum Plaster Boards
Significant volume of Mica Powder are used as a filler in light weight pre-fabricated gypsum wallboards, slabs and panels for building constructions. Mica is light in weight, fire-resistant, free-flowing, chemically inert and non-abrasive. Sound suppression, good thermal and insulation properties, dimensional stability and extremely low water absorption are some of its additional outstanding features. All these desirable characteristics makes mica an ideal and justified filler in plasterboard industry.
For Wallboard Joint Cement Compounds
Mica Powder is a cost effective filler and extender in wallboard joint cement compounds. It is used for filling and finishing the joints, seams and blemishes on gypsum wallboard, between adjacent sheets and other structural constructions. Mica acts as a reinforcing agent improving the workability of compound by preventing cracking, eliminating peeling and reducing shrinkage. The wall surface is protected from moisture absorption since mica particles are insoluble and impenetrable by water. They also provide smooth edge and decorative texture of the wall surface.
For Asphaltic Products
Fairly large tonnage of Mica Powder are used as an inert filler to asphalt and bituminous compositions. Applied as a surface coating to rolled asphalt roofing felt, shingles and damp coarses, mica increases hardness and resistance to mechanical stress and weathering. Mica prevents sticking of adjacent surfaces during manufacture and storage. The coating is not absorbed by freshly manufactured roofing because of the platy structure of mica. It imparts glistening appearance and enhances durability of the roofing product. As compared to other materials, the viability of mica is proven for the above purpose.
For Acoustic Products in Automobiles
Mica Powder is extensively used as a filler in acoustic compounds in the manufacture of automotive components to control noise and insulate the heat generated by commercial vehicles for the comfort and well being of the driver and passengers. The advantages of anti-vibration, sound damping and heat protection utility of mica cannot be neglected. Besides, the addition of mica in acoustic products significantly improves the properties such as increased strength, stiffness and dimensional stability. It also reduces flammability and warping.
For Automotive Plastics
The most wide-spread application of Mica Powder is in automobiles. Mica is used as a reinforcing material in light weight plastic automobile parts such as fascia and fenders, car seat backs, panels and ignition systems. Mica-reinforced plastic imparts improved mechanical properties together with increased strength, rigidity and stiffness. It also provides high heat dimensional stability, temperature resistance, reduced warping and the best surface properties of any filled plastic composite.
For Brake Lining
Mica Powder is used as a friction material for asbestos-free brake lining, brake pads, brake shoes, brake discs, clutch facings, etc. Due to the high thermal resistance of mica, it reduces the flow of heat and helps to keep the brake drums cool. Mica particles are stronger than iron which serves to strengthen and solidify the product preventing microscopic ruptures and minimising warping. Owing to platy structure of the mica, it tends to lock together under compression during processing to form an effective and superior surface. The benefit of mica is also recognized to curb noise and provide active environmental protection.
For Rubber and Tyres
Mica Powder is a highly useful component as an anti-sticking and anti-blocking compound in the production of rubber tyres for automobiles, motor bikes and airplanes. Applied as a dusting and releasing agent, it prevents the inner rubber and casings of tyres from sticking to the mould during vulcanization. Mica prevents movement of sulphur while permitting air and moisture to escape during curing and creating a uniform structure. As a rubber additive and filler, mica improves resilience, hardness, tensile strength and tear resistance of rubber articles.
Mica Powder is broadly used as a functional filler for plastic industries which provides reinforcement. Addition of mica results in high heat resistance, barrier to chemical attack, increased flexural strength and stiffness, extremely low water absorption, low shrinkage and coefficient of expansion, improves dielectric and surface properties of plastic composites. Consumption is suitably dominated in engineering thermoplastic commodities.
Mica Powder is an important constituent as an extender and filler for paint manufacturing. The platy structure of mica reinforces a protective coating in paints. The addition of mica facilitates suspension, reduces cracking and peeling, prevents shrinking and shearing of the paint film, increases resistance of the paint film to moisture penetration and atmospheric weathering, augments performance and brightens the tone of coloured pigments. Utilisation of mica in paints is universally well established for its functional properties.
For Fire Extinguisher Formulations
Mica Powder is essentially used and added in the formulation to keep the powder in dry fire extinguishers free flowing. Mica is fire-resistant and retains the powder mixture from packing tightly in the canister.
For Refractory Bricks
Mica Powder is used in the manufacture of insulating bricks, slabs, blocks and tiles because of its excellent thermal and insulating properties. Since mica bricks can safely withstand extreme temperatures of 1000°C, it keeps heat losses to minimum, minimizes energy consumption, reduces operating costs, enhances furnace efficiency and improves furnace room condition. An additional advantage of mica bricks is stability after long use.