Application of Heavy Calcium Carbonate (GCC) in Paper Industry

　　The development speed of paper GCC in recent years is amazing. In 1996, the consumption was 640,000 tons, and in 2001, it was 610,000 tons, which increased by 9 times in five years. It has become China's fastest growing paper inorganic whiteness mineral pigment. This growth trend is not expected to change in the next five years, with a conservative estimate of more than 900,000 tons in 2005. This is due to the fact that China has a high-quality calcite with a wide distribution and abundant reserves. According to statistics, the high-quality calcite reserves have been found to exceed 600 million tons, mainly distributed in the provinces of Fujian, Zhejiang, Sichuan, Guangxi, Guizhou, Guangdong, Hunan, Hubei, Guizhou, Xinjiang, Liaoning, Liaoning, Jilin, Heilongjiang, Henan, . The second reason for the rapid growth in consumption is that GCC's production technology and equipment have made breakthroughs in recent years. Relevant auxiliaries and grinding media have been localized, resulting in a decline in production costs and further improvement in product quality. Third, in 1999, the output of coated paper and coated paperboard in China increased significantly. Most of the calcium carbonate used in coating pigments in the past used PCC. In recent years, with the modern high-solids large-scale coated paper and paperboard manufacturers, 70 have been put into production. More than % of calcium carbonate pigments are converted to GCC. Fourth, the satellite supply system attached to the large paper mill was completed and put into production, so that the sales price was reduced from 1200 to 2400 yuan/t yuan four years ago to 500-1300 yuan/t yuan for the current filler and coating grade products. At present, it takes only 150,000 US dollars to build a 10000t/a wet D90 product satellite production line using domestically produced equipment with automatic control system. Such low investment and price will undoubtedly bring great appeal to consumers and affordable economic benefits. Fifth, GCC can be used both as a paper filler and as a paint pigment. According to the foreign consumption ratio and the development trend of domestic alkaline papermaking, the development potential of GCC filler is huge.

　　According to incomplete statistics, China has built more than 30 paper-making GCC production enterprises, with a total production capacity (including foreign-funded and joint ventures) of about 800,000 t/a. Among them, small enterprises with less than 10,000 t/a in the early stage of domestic equipment have poor product quality stability and low market competitiveness, and most of them are facing elimination. At present, there are 14 domestic enterprises with 30,000 t/a or above. The largest satellite production enterprise is the 220,000 t/a production line of Zhenjiang APP Group. Secondly, the three subsidiaries of Jiangsu Xingyi Company have a total production capacity of 150,000 t/a. The GCC producer with the largest output is Anwei ECC (now “Ingrid Porcelain” company acquired by IMERYS, France). Tangshan Tianying Chemical Co., Ltd. is the only professional manufacturer of papermaking D90GCC imported from Germany's Nichichi horizontal mixing mill, with an annual output of 15,000 tons.

　　Five years ago, the high quality GCC in China's paper industry relied mainly on imports. At present, localization is basically achieved except for individual paper mills. Although the overall equipment level of domestic paper-making grinding CaCO3 lags behind that of foreign advanced equipment for 10 years, there is no major technical difficulty in producing coated grade GCC products with small-scale domestic equipment to produce filler grade, primer grade and general technical requirements. However, there are still some gaps in the degree of automation control in the production of high-quality top-coating products and narrow-grained products with higher solid content, as well as the technology of wet-grinding and drying products and the quality of large-scale equipment. These technical difficulties are expected in 2005. Years can be overcome. The development characteristics and trends of China's paper GCC are mainly reflected in the following aspects:

　　1 Relying on a large paper company or building a GCC production supply system in a concentrated area of papermaking enterprises is currently the main mode of construction. It is predicted that in 2005, there will be another four satellite production lines of more than 10,000 tons in operation. After the new 180,000-ton production line of Jindong Paper is put into production, the total production capacity of the plant will reach 400,000 tons.

　　2 France, Japan, Taiwan, Malaysia, South Korea, the United States, Indonesia and other foreign companies have entered the Chinese papermaking GCC industry, which has a production capacity of nearly 600,000 tons. Currently, about 50% of papermaking GCC products are provided by foreign capital or joint ventures. And there is a trend to further expand the market.

　　3 product grades develop toward a narrower particle size distribution. At present, the particle size distribution of the papermaking GCC products processed by wet processing is mostly in the range of 9 to 13 grains. The newly developed production technology of the China Pulp and Paper Research Institute can be controlled at 7 to 9 sizes. The concept of "engineering pigment" proposed by foreign countries in recent years for paper coating pigments, the central meaning is to improve the optical and printing properties of a coated paper by using a narrow particle size distribution GCC. Tests have shown that too fine GCC can improve paper whiteness and white paper gloss, but it also reduces printing gloss and opacity. Engineered pigments have the best particle size and air permeability to improve coating pigment arrangement and pore structure for better printed images.

　　4 Product whiteness (brightness) indicators climbed. The domestically popular papermaking GCC whiteness has risen from 90% to 92% six years ago to 94%, and there is a trend of further improvement. At present, the highest whiteness of D90 products can reach 96-97%. The consumption of such high whiteness products in foreign countries is not large and the price is high. It is mainly used for high whiteness paper and instead of TiO2. The high whiteness products favored by domestic paper consumers are not used in the market, and the price is high. It is mainly used for high whiteness paper and instead of TiO2. The preference of domestic paper consumers for high whiteness is one of the reasons for the rise in whiteness. GCC producers have also contributed to the increase in whiteness by increasing whiteness without increasing prices as a means of sales. On the one hand, this phenomenon reflects the market demand for high whiteness paper, and also reflects the imperfections in the use of paper mills, the unreasonable price, and the irrationality of the use of limited high quality calcite resources in China.

　　5GCC slurry products are developed to high solids content. The 25-30% water-containing mud cake is the main product form in the early stage of GCC development. At present, this product form has been basically replaced by slurry and dry powder. At present, most domestic GCC companies can produce 70-75% solids slurry. The China Pulp and Paper Research Institute uses a new modified mill to prepare D902μm slurry products with a solid content of 78-80, so that users can not add dry powder. Next, prepare more than 68% of high-concentration paint.