| The aim of choosing dispersing agent in slurry of heavy calcium carbonate used for paper coating for better application was investigated. The conditions on the application of dispersion agent were optimized.Firstly, nine brands of dispersing agent in slurry of heavy calcium carbonate used for paper coating were collected through the market survey. Five of them showed neutral property, and the other showed acid property. These nine brands of dispersing agent were tested for viscosity, solid content, pH value and density. The similarities and differences of them were studied. Then the molecular weight and its distribution were tested using gel permeation chromatograph after finding small difference. The similarities and differences between the five kind of neutral dispersing agents and four kind of acid dispersing agents were compared.The orthogonal experiment was designed. The influence of the same conditions on initial solid content, solid content of 1 hours, solid content and initial viscosity of 4 hours, solid content of 8 hours, viscosity of 1 hours, viscosity of 4 hours, viscosity of 8 hours of heavy calcium carbonate was analyzed.Two kind of optimal dispersion agent were chosen to carry out orthogonal experiment. The optimal dosage of neutral and acid dispersing agents was confirmed through studying the influence of dosage of dispersant agent on initial solid content, solid content of 1 hours, solid content and initial viscosity of 4 hours, solid content of 8 hours, viscosity of 1 hours, viscosity of 4 hours, viscosity of 8 hours of heavy calcium carbonate. It showed the optimal dosage of neutral and acid dispersing agent was 0.9%-1.2% and 0.6%-0.8% respectively.Finally, addition point and dosage of neutral dispersant agent were fixed. Adding mode and its effect on grinding efficiency of acid dispersant agent in the grinding process were discussed. The result showed the effect was promoted with longer dropping time during the grinding process. |
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