Calcium Carbonate :
Calcium carbonate is used in paper mills as a filler material in the alkaline papermaking process. Nowadays Calcium carbonate is dominant over other papermaking filler materials. The main reason behind the preference of calcium carbonate is the demand for brighter and bulkier paper. There are significant benefits to the use of calcium carbonate in the al¬kaline papermaking process. But Calcium Carbonate filler is unsuitable in acid papermaking and wood-containing paper. Main reason for using Calcium Carbonate Powder is in paper production to enhance the brightness and opacity of paper and pulp.
Magnesium Carbonate (Dolomite):
Used as a filler to give smoothness, porosity and opacity to paper in addition to reducing the cost.To control Pitch and Stickiness, during the paper making process, oleo resinous droplets micro or colloidal in nature get added to the stream.
In coating formulation, because of its high brightness, talc leads to reduction in usage of expensive whitening and helps in controlling gloss of the coat. Talc also provides smoothness to the surface and imparts opacity to the coat. Additionally talc reduces the friction on paper manufacturing machinery thus reducing wear.
Magnesium Silicate (Talc):
Talc is used in both uncoated and coated rotogravure papers where it improves printability as well as reducing surface friction, giving substantial improvements in productivity at the paper mill and print house. It also improves mattness and reduce ink scuff in offset papers. Used as pitch control agents, talc “cleans” the paper making process by adsorbing any sticky resinous particles in the pulp onto their platy surfaces, thereby preventing the agglomeration and deposition of these on the felts and calenders. As opposed to chemical pitch-control products that pollute the process water, talc is removed together with the pulp, enabling the papermaker to operate more easily in closed-circuit. In specialty papers such as colored papers or labels, talc helps to improve quality and productivity.