Specialty Minerals Inc. (SMI), a subsidiary of Minerals Technologies Inc., manufactures precipitated calcium carbonate (PCC) for paper mills at plants located at the paper mill site. PCC is used in fine white paper as a filler and coating material. SMI PCC improves the quality of the paper while  reducing significantly the amount of wood pulp used by the mill to make paper. Specialty Minerals combines carbon dioxide from the paper mill’s limekiln, boiler, or other combustion gas source, with lime and water to produce PCC, which is then pumped to the paper mill.  

There are a number of environmental benefits resulting from the onsite location of a Specialty Minerals PCC facility at a customer’s paper mill. These include:  

Air
The PCC process reduces the amount of sulfur compounds (both sulfur dioxide and total reduced sulfur) produced at the paper mill site. The SMI PCC process also recaptures a portion of the carbon dioxide from the paper mill’s combustion processes and converts the CO2 gas to PCC product.  

Water and Wastewater
The SMI PCC plants use cooling towers and other systems to recover and reuse the water and material in the wastewater. These systems reduce the amount of water used by the PCC plant and the amount of wastewater and solids produced.  

Typically, all of the wastewater from the PCC plant is treated at the paper mill's wastewater treatment plant. The wastewater from a PCC plant is only a small fraction (less than 5 percent) of the total volume treated by the paper mill’s wastewater treatment plant.  

By-products
One of the keys to the success of Specialty Minerals PCC products is careful control of the size of the PCC particles. SMI removes oversized particles that, at many locations, are used as a replacement for agricultural lime by area farmers to increase the pH of the soil, for a beneficial impact on crops.  

Traffic
Other filler and coating products must be hauled to the paper mill in the form of a water slurry. SMI’s processes use water and raw materials already available from the paper mill to produce our products. Production right at the mill reduces traffic into the mill, thus lowering air pollution, congestion, noise, and fuel consumption.