In recent years, the import volume of calcium carbonate in China has basically remained at 30,000-50,000 t/a, while the export volume has increased steadily, from 79,700 t in 2011 to 121,300 t in 2019. At the same time, export prices have gradually increased, and the import-export price ratio has dropped steadily from 2.85 in 2011 to 0.78 in 2020.

Taking 2019 as the critical point, the export price exceeds the import price, which shows that the quality, added value and price of Chinese calcium carbonate products are increasingly recognized by the international market, and gradually get out of the low-end lock, which reflects from one aspect that China is steadily moving towards calcium carbonate Production powerhouse.

The paper-making industry is one of the largest markets for calcium carbonate. With the development of paper-making technology, the paper-making process has changed from acidic paper-making to neutral and alkaline paper-making, and the consumption of calcium carbonate in the paper-making industry has greatly increased. Especially in recent years, my country's traditional paper-making industry is undergoing structural adjustment and product transformation and upgrading. As an indispensable and important white inorganic filler and pigment in the paper-making industry, calcium carbonate is increasingly playing its unique and important role.

Application of Calcium Carbonate in Paper Industry

1. Application as filler in paper-making

As a paper filler, calcium carbonate can improve the optical properties of paper products, the smoothness of paper, the forming of paper sheets, the printing adaptability and writing adaptability of products, and because its cost is much lower than that of pulp fibers, it can significantly reduce production costs.

On the other hand, excessive addition of heavy calcium carbonate will also cause the separation of the bonds between fibers, resulting in damaged paper such as reduced paper strength, bulk and stiffness. However, there is no binding force between light calcium carbonate and pulp fibers, resulting in a low retention rate. Therefore, regardless of heavy calcium or light calcium, it needs to be modified for better application in paper-making. Fillers for paper-making must meet the following conditions:

(1) The particles are fine and uniform, and the retention rate is high.

(2) The color is pure white, glossy, and has good printability.

(3) High purity, free of other impurities, insoluble or difficult to dissolve in water.

(4) It has strong covering ability, low transparency, high refractive index and high scattering coefficient.

(5) The chemical properties are stable, and it is not easy to be deteriorated by acid, alkali or chloride reduction.

(6) Abundant resources and low cost.

2. Application in paper making coatings

In terms of paper making coatings, due to its high whiteness, large surface area, high surface activity, high strength and hardness, nano-calcium carbonate is of great help to improve the quality of paper. Adding nano-calcium carbonate to the coating can improve the gloss and ink absorption, and improve the smoothness of the paper.

From the perspective of the development of the paper industry, the application fields of calcium carbonate are very broad, and the application prospects in the paper industry are even more inestimable. Rational use of calcium carbonate raw materials will help paper mills reduce consumption and improve quality, and will achieve better economic and social benefits.