Technical application of laser particle size analyzer in paper industry

In recent years, the rapid development of China's papermaking industry has led to the continued growth in the consumption of mineral powder materials for papermaking. Major non-mineral powder materials such as calcium carbonate, talc, and kaolin have become indispensable and important raw materials for the modern papermaking industry. The retention of mineral powder materials as papermaking fillers has a great impact on the quality and function of paper. The particle size and particle size distribution of mineral raw materials are important factors affecting the filler retention rate.

The impact of filler particle size on paper production

Today's fillers in the paper industry are mainly mineral powder materials such as ground calcium carbonate, precipitated calcium carbonate, talc, kaolin and titanium dioxide. There are many factors that affect the retention rate of these fillers in the papermaking process. Practice has proven that in addition to papermaking process control factors such as pulp type, additive application and papermaking machine operating parameters, the size, microscopic shape and particle size distribution of filler particles have a great impact on the retention rate in the papermaking process.

Adding fillers during the paper manufacturing process will cause lint and powder loss during the rewinding, slitting and printing processes. The unreasonable particle size and particle size distribution of the filler are one of the important factors causing the phenomenon of lint and powder loss. In addition, when the microscopic morphology of the filler is basically consistent, the filler with a narrow particle size distribution is beneficial to retention during the paper making process. Tests have shown that when the ash content of the paper is consistent and the various physical indicators of the finished paper, such as basis weight, whiteness, secondary length, tensile strength, etc., meet the requirements, different filler varieties with the same microscopic morphology and basically the same average particle size can be used. , the retention rate of fillers with narrow particle size distribution is significantly improved.

The following is a comparison of the dynamic adding amounts of different fillers during the test when the paper quality meets the requirements (Table 1). When all indicators are met, No. 1 filler (synthetic light calcium carbonate) has a more ideal particle size distribution. Due to its increased retention rate, the amount added is reduced by about 1/4 compared with No. 2 filler. Fillers with narrow particle size distribution can be used as papermaking fillers to improve their retention, reduce paper manufacturing costs and appropriately reduce the load of papermaking wastewater treatment.

Table 1 Comparison of PCC dynamic addition data

Sample data Adjustment amount No. 1 synthetic light calcium carbonate No. 2 synthetic light calcium carbonate

Concentration adjustment g/L 155~167 160~170

Dynamic addition amount L/min 7~8 10~11

Average flow L/min 7.5 10.5