![]() In chalks, remnants of animal shells and skeletons are often still seen. If the time, temperature and/or pressures are not great, the seabed only partially metamorphoses, and the result is very soft chalk, such as that forming the White Cliffs of Dover in England. If this kind of geological process continues a very long time, the crystals become very small, forming marble, an extremely hard form of calcium carbonate. All of the organic matter that was in the deposit was removed by oxidation, a process called diagenesis. Over a period of five hundred million years this deposit was under high temperature and high pressure, and the deposit changed to a coarsely crystallized limestone. These shells and skeletons were largely composed of calcium carbonate. This limestone deposit is the result of a very thick layer of prehistoric sea animal shells and skeletons being laid down on the ocean floor. (SMI) uses high quality limestone sources for its PCC products, including some from the SMI limestone mine in Adams, Massachusetts, which has been in operation for more than 150 years. PCC is generally made from a high purity calcium carbonate rock called limestone. What Is Precipitated Calcium Carbonate (PCC) Made From? This body of PCC technology developed by Specialty Minerals Research, is what makes SMI PCCs outstanding in quality and consistency. While the process is simple on a laboratory scale, making precipitated calcium carbonates commercially on a large scale requires a great deal of process control and process technology to assure the right size, uniformity, shape, surface area and surface chemistry. If the PCC is to be used as a dry product, the slurry is dewatered, dried, milled, packaged and tested.If the PCC is to be used in a paper mill or shipped to a latex paint plant, the lower solids slurry may be used as is, or processed to bring up the solids level, then tested before transfer or shipment.Separate additional impurities and grit from the PCC slurry.Calcium carbonate reforms, and since it is insoluble in water, precipitates out. Combine the captured carbon dioxide with the slaked lime.Separate out additional impurities from the slaked lime.Add the lime to water to form calcium hydroxide (hydrated lime or slake).The carbon dioxide can be captured for reuse. ![]()
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