In today's world of growing demand for consumer items the role of a filler assumes very significant part in the manufacture of various products such as dentifrice, cosmetics, printing inks, papers, PVC and other plastics, rubber, pharmaceuticals, paints, distemper etc. Filler that has attracted considerable interest in recent times is calcium carbonate. Calcium Carbonate is one of the widely accepted filling agents all over the world. The role of calcium carbonate as a filling agent was identified way back and it continues to enjoy the same status of a filling agent even today in numerous newer fields. The future of this filling agent also is bound to be bright in the absence of any other filling agent.
Limestone is the natural form of calcium carbonate and it is either used as such in industries or further processed according to the requirements of the consuming industries. Precipitated calcium carbonate is one of such processed product of limestone.Chemically processed calcium is sold in two forms, I. E. Precipitated calcium carbonate, and activated calcium carbonate the coated variety.
Precipitated calcium carbonate is an uncoated variety, which is mostly used in the preparations of tooth powder, tooth paste, face powder, creams, pharmaceuticals, paints, paper etc. It is also used in certain PVC articles like rexin and footwear manufacture and as filler and chemical agent in number of chemical industries.
Precipitate Calcium Carbonate is synthetically processed from naturally occurring high grade lime stone. The material is brilliant white and can be supplied in different bulk densities from 0.28 gms/cc to 0.9 gms/cc, depending upon the requirement of end user.
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is obtained when calcium oxide (called lime or quicklime) is mixed, or "slaked" with water.
This grade is processed through naturally occurring high purity ores containing CaCO3 as major component. The ores are subjected to beneficiations and up gradation to obtain different qualities of grounded calcium carbonate depending on sorting of lumps to process involved.
Precipitated calcium carbonates are used as fillers in adhesives and sealants. However, because of their much smaller sizes they are mainly used as the primary rheological additive in high-performance products. PCC's add reinforcement and make the product stronger.
PCC's are used as dietary calcium, mostly in liquid products where the very small particle size is valuable. Many medicines and cosmetics contain PCC, as the base material of pills, or for bulking of liquid medicines, ointments or creams. PCC's are used in toothpaste as a viscosity aid and mild abrasive.
Precipitated calcium carbonate (PCC) is commonly used in paint and inks as extenders to increase opacity and porosity for dry hiding. Formulating flexographic, gravure, lithographic or silk screen printing inks with PCC can improve quality whilst reducing costs.
PCC is used for similar applications to GCC but the particle size is much finer and more closely controlled, allowing PCC to be used more for paper coating and surface finishing. PCC can be supplied coated with additives to improve gloss or aid bonding within the paper.
PCC is used as a fine and very consistently controlled filler/extender, and also to help control flow and moulding characteristics of fine components. PCC also has a significant effect on impact strength in rigid PVC.
As essential ingredient in powders and pastes as a cleaning and polishing agent. Used for its abrasive property in Tooth powder / Toothpaste.
Reinforcing filler in natural and synthetic rubber for Tyre/ Tubeapplications as well as slippers, soles, straps to improve strength & impart whiteness while reducing total costs.
In Detergents it is used as a carrier and also to improves the water absorbency in powder & protects the skin at the time of use of the same.
One significant application of calcium hydroxide is as a flocculant, in water and sewage treatment. It forms a fluffy charged solid that aids in the removal of smaller particles from water, resulting in a clearer product. This application is enabled by the low cost and low toxicity of calcium hydroxide. It is also used in fresh water treatment for raising the pH of the water so pipes will not corrode where the base water is acidic because it is self-regulating and does not raise the pH too much. Another large application is in the paper industry, where it is used in the production of sodium hydroxide. This conversion is a component of the Kraft process
In road construction, to improve the quality of excessively plastic subgrade soils.
In the production of metals, lime is injected into the waste gas stream to neutralize acids, such as fluorides and chlorides prior to being released to atmosphere.
Limestone is a common sedimentary rock composed primarily of the calcium carbonate mineral, calcite (CaCO3). Limestone constitutes approximately 10 percent of the sedimentary rocks exposed on the earth’s surface. Limestone is formed either by direct crystallization from water (usually seawater), or by the accumulation of sea animal shells and shell fragments.
GCC is often the main ingredient of sealants, fillers and ceramic tile adhesives (CTA's), sometimes up to 80% of the formulation
GCC has long been used as a filler in materials like asphalt, roofing felt and plasters. Increasingly other applications are emerging in the new areas of specialist concretes & grouts. Consistent particle size and handling characteristics are very important.
GCC is a wholly naturally occurring source of alkalinity used for flue gas desuphurisation in power stations, de-acidification of forests and rivers, and drinking water treatment. It can also be used as passive fire protection in hazardous environments, for example coal mines.
Manufacturing of PCC and its allied products start with the selection of pure raw materials. Selected raw materials are subjected to cleaning process which includes washing and sorting. Crushing, Burning and after passing number of complex chemically processing steps, it gives the final product and latest technology and manufacturing equipment has improved the quality of the products.
Calcium oxide reacts with water releasing a considerable amount of heat to form calcium hydroxide. CaO + H2O => Ca(OH)2 + heat The reaction requires about 320 gr. water for each kilogram of calcium oxide. Additionally, the heat released by the reaction usually causes a large amount of slaking water to evaporate. In practice, the process is steered so that the amount of water used is exactly equal to that required by the reaction and the subsequent evaporation. The result is a dry, powdery hydrated lime.