MICA FLAKES have been preferably used in water-based and oil based oil-well drillings operations as an additive mud chemical to prevent loss of circulation and seepage. Mica is specially added to seal-off the lost circulation zones. The platy structure of mica facilitates the overlapping of particles to form a layer or wall and acts as a sealent that bridges the openings. The use of mica helps to seal porous formations and contributes to regain circulation keeping the solids in suspension.

The technique adopted is to mix quantities of mica flakes and granular bentonite into special batches of mud which is pumped down the hole. The drill pipe is then withdrawn and the hole left undisturbed for a time being. Mica flakes tends to plate out on the walls at the lost zones and reduce the size of the holes through which the mud can pass. After a short interval, the plug is strong enough to permit circulation to resume without loss. Drilling then proceeds normally until a depth well below the lost circulation zone.

What is Mica and Mica Flake?
Mica is a non-toxic silicate mineral that has been used for centuries. Most mined mica is in blue and green colors, but iron oxides and other additives are used to make it different in color. Heat-treating is sometimes used to increase the metallic appearance of mica. Mica Flakes is mica slices ground into sizes ranging from 0.5 Millimeter to 7 Millimeter. This material is prepared mainly by the means of rotary hammer crushing machine in which the mica is literally beaten till some time that the required size is not achieved and the material passes out from graded sieves. When ground into a powder, mica displays a translucent shine that has made it a favored ingredient in cosmetics since ancient times. Its ability to reflect light means that it is used in small amounts for items such as face powders and highlighters. It’s used in larger quantities in lipstick and eye shadow, where it’s a key coloring ingredient. Mica powders are one of the foundational ingredients in most mineral makeup.

“Micro-Silica usage in cement”
Micro-Silica is very high in fineness and in silica content, and a very effective pozzolanic material depending on free lime content of cement use. On the other hands, it is known as a reducer of the permeability of concrete and increaser of the concrete strength and durability. On the negative side, it effects color, water demand. Because of its extreme fineness, micro silica presents handling problems, slump loss, stops bleeding of concrete. The dosage rate depending on what you are trying to achieve, typically around 5-15% of by weight of cement.

Suitably used for sealing openings. Apparent density = 0.17kg/ltr. Particle Size : Max 10% retained on 9.50mm B.S.Sieve. Material retained on Sieve 4.75mm + material passed through 1.70 mm = 30-40% Max.

Generally used to combate mild circulation in porous formations. Apparent density=0.18 kg/ltr. Particle size: Max 10 % retained on 3.35 mm B.S.Sieve. Material retained on 1.70 mm + material passed through Sieve 0.425 mm = 30-40% Max.

Suitable for use when a sealing agent is needed to be small enough to pass through a shaker screen without interfering with the operations. Apparent density=0.20 kg/ltr. Particle size : Nil retained on 0.850 mm B.S.Sieve. Matertial retained on Sieve 0.425 mm + material passed through sieve 0.15 mm = 30-40% Max.

Mica minerals are major rock forming minerals found in gneiss, schist and granite. The mica group includes muscovite mica and biotite mica. They usually form in layers of sediment on ocean floors. Weathering of continental rocks breaks large and small chunks of rock off the larger older rocks. Rain water and river water breaks the materials down even further creating a variety of sediments. The sediments are carried to the sea by large rivers like the Mississippi and Amazon Rivers. Each rainstorm brings a new layer of sediment that settles on the seafloor on top of the previous layers. Each layer increases the depth of the sediment that produces heat and pressure on the sedimentary layers below them. The upper layers create downward pressure on the sedimentary layers that lie beneath them. The upper sedimentary layers compress the moisture out of the sediments due to the weight of the overlying layers. The bottom layers turn into shale, a sedimentary rock shale due to the heat and pressure. Micas are common minerals that crystallize in these layers. When shale recrystallizes forming microscopic mica minerals between the sedimentary layers the rock turns into slate, a metamorphic rock. Source: http://kids-earth-science.com