Stone powder (Calcium carbonate) is now considered as the most widely used powder filler, especially in the plastic industry. This material is not expensive, it not only reduces the cost of raw materials investment up to billions of dollars, but it can further save other resources such as oil that is not renewable on earth.
Various stone powders are widely used which reduces the cost of plastic materials and improves performance. There are two main types of stone powder: superfine calcium carbonate powder (Ground calcium carbonate) and precipitated calcium carbonate.
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Features of ultra-fine stone powder
The production of stone powder goes through many stages such as mining and blasting, crushing, crushing, filtering out dirt and impurities, taking stones with high calcium content, classifying the purity and whiteness. Then grind it to the size required by the customer.
Ultra-fine stone powder or GCC calcium carbonate powder is formed directly from crushing limestone into powder, used as an additive for the industries of paint, plastic, paper, rubber, cosmetics, chemicals… It is also used in cement, which is converted to quicklime (calcium oxide) and slaked lime (calcium hydroxide). In Vietnam, the standard parameters of superfine stone powder can reach the index: Whiteness: 98.5% / Brightness: 96% / CaCO3 content: 98%.
The difference between Ultrafine Calcium Carbonate (GCC) and Precipitated Calcium Carbonate (PCC)
1. Origin of formation
Precipitated calcium carbonate is chemically produced and precipitated as a powder. Ultrafine calcium carbonate powder is a kind of mechanical calcite that directly crushes natural calcite, marble, chalk, shells, and other preparations.
2. Mass density
The most obvious difference is the block density between GCC and PCC. The bulk density of GCC is relatively large, usually 0.8-1.3g/cm3. PCC has a density less than 0.5-0.7g/cm3; Some calcium carbonate powder products have even lower packing density, which can reach about 0.28g/cm3.
3. Brightness & whiteness
Because superfine stone powder products have relative impurities, the brightness of the products is generally 89% to 93%, a very small number can reach 95%. Precipitated calcium products are chemically synthesized and removed many impurities, so the product has high purity. It will lead to the whiteness from 92% to 95%, some products can reach 96% to 97 %.
4. Humidity Index
The GCC humidity is generally 0.2%-0.3%, the relative humidity is low and relatively stable, some high-grade calcium carbonate powder can even reach about 0.1% humidity. Precipitated calcium carbonate PCC normally has moisture 0.3% -0.8%, sometimes there will be some unstable fluctuations.
5. Particle Size
GCC products have particle sizes in the range of 0.5-45um, product size due to different crushing equipment. Normal PCC product particle size is usually 0.5-15um. Typical PCC particle sizes are around 2,500 mesh to meet the performance requirements of PVC pipes and components. Previously, due to the limitations of grinding equipment, GCC superfine stone powder could not achieve this fineness, but due to technological changes and modern machinery, now the particle size of GCC can meet demand is even smoother than PCC and is being used by more manufacturers.
6. Oil absorption index
PCC calcium carbonate powder‘s oil absorption value is 60-90ml/100mg, much larger than GCC calcium carbonate powder 40-60ml/100mg, so liquid absorption capacity and absorption resin efficiency are very high.
Therefore, in the production formula of PVC pipes, if the manufacturer chooses PCC, it is necessary to consume more liquid additives, so from the oil absorption value, it is possible to consider choosing the superfine stone powder GCC with low oil absorption.
7. Cost and economic efficiency
The processing of GCC ultrafine stone powder is mainly done by mechanical crushing and grinding. PCC precipitated stone powder production process is prepared by a chemical reaction precipitation reaction, the process is more complicated than superfine stone powder, the requirements are also much more stringent, so the production cost will increase. Therefore, if the economic problem is effective for businesses, it is recommended to use GCC superfine stone powder to save money.