Calcium Carbonate
Decanters from GEA Westfalia Separator are used in GCC and PCC processes. The recovery of high-purity particles extending down to the nano range meets the industry’s highest quality standards.
Calcium carbonate is used in a broad spectrum of applications. Besides its use as a filler for paints and plastics, it plays an important role as a coater in the paper industry. CaCO3 from marble is the ideal inorganic pigment to produce bright white, multi-coated paper in photo print quality.
Intelligent treatment techniques are required for classifying, sorting and dewatering calcium carbonate. The product quality and market price are determined by the particle size distribution and purity. The decisive factor is the concentration of the valuable particles with a size < 2 μm and a dense particle distribution. A higher process flexibility must also be assured to recover different quality grades and to boost the recovered yield.
A fundamental differentiation is made between ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC). In the traditional GCC method, blocks of marble are ground before being classified and dewatered to the specifications of the intended application. In the innovative production of PCC, the process configuration is exactly the opposite. Individual crystals are stimulated to grow in a reactor by adding calcium oxide and are then dewatered. GEA Westfalia Separator supports both processes with customized and individually configured process lines.
Recovery of ground calcium carbonate (GCC)
Production of precipitated calcium carbonate (PCC)
Very precise classification cut
The new decanter generation is specifically designed for the recovery of particles in the micro and nanosize range. The continuous processing mode supports solid-liquid separation and classification by different particle sizes and liquid densities. The very precise classification cut enables the particle size distribution to be adjusted so that the quality specifications are always spot-on. Adding on a second classification stage has the advantage that existing product losses can be transformed into the desired higher quality without excessive expenditure.
Dewatering of the superfine particles to a dry substance content in excess of 70 percent subsequently ensures controlled, stable solids concentrations. Clarification additionally minimizes the contaminants. Whether GCC or PCC: the result is in either case a highly pure, pasty slurry which fulfils all the demands of the paper manufacturer.
At a glance:
- Continuous process
- Support of GCC and PCC recovery
- High product purity
- High yields, less product losses
- Dry substance contents of more than 70 percent
Process line for calcium carbonate
