New technique for refining filler of calcium carbonate from lime mud

Abstract

This invention relates to a new process for refining calcium carbonate filler from white mud. The process comprises: preparing the raw materials, washing, roughly screening, homogenizing, deflocculating, carbonizing, finely screening, and storing. In the process, homogenizing, deflocculating, carbonizing are accomplished in a single step. Calcium carbonate has a particle size D50 of 3.0-7.0 mums, and an average particle size of 5.5-8.5 mums. The recovered lightweight calcium carbonate has whiteness higher than 89% ISO, Ph value of 8.4-10.5, sedimentation volume greater than or equal to 2.6 mL / g, and slurry calcium carbonate concentration of 14-16%. The product is qualified for use in high-class writing paper, and the cost is only 1 / 3 that of commercialized lightweight calcium carbonate.

Description

1. Technical field: [0001] The invention relates to a new technology of white mud refining filler calcium carbonate, a by-product produced in the pulping and papermaking process. 2. Background technology: [0002] "Resources" and "environmental protection" are two major factors restricting the development of the paper industry today. Papermaking black liquor is the most serious pollution. Alkali recovery is the fundamental way to control the pollution of papermaking black liquor. However, the secondary pollution caused by a large amount of alkaline waste residue (white mud) produced by alkali recovery is a major issue that must be solved in alkali recovery. The white mud discharged from the causticizing process is recovered by alkali process wood pulp, and the calcined regenerated lime can be recycled in causticizing. Alkaline straw pulp white mud, due to the high content of silica, calcined regenerated lime, causticizing cannot be recycled. my country is a big straw pulp ...

AI Technical Summary

Problems solved by technology

However, due to high processing costs or technical problems, scale production has not been formed, and it is still in the exploratory stage.

However, the above two methods are still difficult to apply and popularize at present. The main reasons are: the first method has high equipment investment, low whiteness of calcium carbonate produced, uneven material particle size, and chemical instability in the wet end during paper machine filling process. , the paper is easy to lose hair and powder; the second method is that the pretreatment quality of lime and green liquor is difficult to guarantee to meet the process requirements. There are still many technologies to be explored in actual production. The whiteness, D50 particle size, and average particle size of the produced calcium carbonate are quite different from those of commercial calcium carbonate. There are still many technical problems in the application of paper machines, especially in the application of high-speed paper machines.

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