Improved preparation technology of white mud calcium carbonate for papermaking filler

A preparation process and paper-making filler technology, which is applied in the production of calcium carbonate/strontium/barium, lime, etc., can solve the problems of difficult production operation, unfavorable white mud washing, and affecting the effect of white liquor secondary pulping, etc., to improve white liquor The effect of mud whiteness

Inactive Publication Date: 2013-03-20
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this way, the S in the causticizing reaction system is firstly consumed 2- , so that there is no Na in the generated white liquor 2 S, affects the secondary pulping effect of white liquor; at the same time,

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] (1) After crushing the lime, sieve it with a 400-mesh sieve, digest the sieved fine lime and prepare fine lime milk for later use;

[0024] (2) Sieve the coarse lime for digestion, use a 400-mesh sieve for sieving, remove impurities in the lime milk and prepare for green liquor causticization;

[0025] (3) Place the turbid green liquid from the combustion section in the preprocessor, and add 0.2% (for Na in the green liquid) at a temperature of 70°C 2 O mass meter) fine milk of lime, after being stirred evenly, transfer to the green liquor clarifier, and the clarification time is 8 hours;

[0026] (4) Add milk of lime with a theoretical reaction volume of 105% to the purified green liquor for causticization, the causticizing stirring speed is 300 rpm, the temperature is 85°C, and the time is 4 hours to prepare the alkali recovery white mud suspension;

[0027] (5) Pass the obtained lime mud suspension into a vacuum pulp washer to separate the white mud from the white l...

Embodiment 2

[0031] (1) Crush the lime and sieve it with a 300-mesh sieve, digest the sieved fine lime and prepare fine lime milk for later use;

[0032] (2) Sieve coarse lime for digestion, use a 200-mesh sieve for sieving, remove impurities in lime milk and prepare for causticization of green liquor;

[0033] (3) Place the turbid green liquid from the combustion section in the preprocessor, and add 0.1% (for Na in the green liquid) at a temperature of 60°C 2 O mass meter) fine milk of lime, after being stirred evenly, transfer to the green liquor clarifier, and the clarification time is 6 hours;

[0034] (4) Add milk of lime with a theoretical reaction volume of 107% to the purified green liquor for causticization, the causticization stirring speed is 500 rpm, the temperature is 75°C, and the time is 3 hours to prepare the alkali recovery white mud suspension;

[0035] (5) Pass the obtained white mud suspension into a vacuum pulp washer to separate white mud from white liquor, wash whit...

Embodiment 3

[0039] (1) After crushing the lime, sieve it with a 200-mesh sieve, digest the sieved fine lime and prepare fine lime milk for later use;

[0040] (2) Sieve coarse lime for digestion, and use a 100-mesh sieve for sieving to remove impurities in lime milk and prepare for green liquor causticization;

[0041] (3) Place the turbid green liquid from the combustion section in the preprocessor, and add 0.15% (for Na in the green liquid) at a temperature of 50°C 2 O mass meter) fine milk of lime, after being stirred evenly, transfer to the green liquor clarifier, and the clarification time is 4 hours;

[0042] (4) Add milk of lime with a theoretical reaction volume of 110% to the purified green liquor for causticization. The causticization stirring speed is 400 rpm, the temperature is 50°C, and the time is 4 hours to prepare the alkali recovery white mud suspension;

[0043] (5) Pass the obtained white mud suspension into the white mud pre-hanging machine to separate the white mud fro...

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PUM

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Abstract

The invention relates to an improved preparation technology of white mud calcium carbonate for a papermaking filler. The improved preparation technology comprises the following steps of: firstly, pretreating a turbid green liquor from a combustion section by using fine milk of lime, and then adding causticized milk of lime for causticization to obtain an alkali recovery white mud suspension liquid; introducing the white mud suspension liquid into a white mud pre-coating machine or a vacuum pulp washer for separating white mud and white liquor, washing the white mud, and then sieving to remove large granular coarse residues; introducing industrial liquid CO2 into the washed and coarsely sieved white mud suspension liquid for carrying out deflocculation and secondary carbonization; and finally adding a decolorizer for reaction, and sieving to obtain the white mud calcium carbonate. The improved preparation technology has the advantages that the fine milk of lime is used for pretreating the green liquor and enabling solid matters in the green liquor to be cooperatively precipitated in a precipitation generation process, so that the impact of the solid matters on the whiteness of the white mud is eliminated; and colored matters formed by non-ferrous metal ions introduced by the causticized milk of lime are reserved in the causticized white mud, and the causticized white mud is bleached to remove the color after secondary carbonization, so that the whiteness of the white mud is increased, and the refining of the white mud calcium carbonate for the papermaking filler is realized.

Description

technical field [0001] The invention relates to high-value utilization of white mud recovered from wheat straw pulping alkali, in particular to an improved preparation process of white mud calcium carbonate for papermaking filler. Background technique [0002] Papermaking white mud refers to the precipitated calcium carbonate formed after the causticizing reaction of green liquor and slaked lime in the alkali recovery process. Because it contains a certain amount of water, it is called white mud. The annual production of white mud in my country's paper industry exceeds 4 million Ton. As a residue from the alkali recovery process, lime mud contains a large amount of CaCO 3 , also contains a small amount of alkaline substances and other ingredients. Since the silicon content of grass raw materials is much higher than that of wood raw materials, the silicon content of alkali recovery lime mud from grass materials is high, and the quicklime after calcination is easy to harden, ...

Claims

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Application Information

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IPC IPC(8): C01F11/18
CPCY02P40/40
Inventor 王建张丹王晓龙徐永建高先强刘羚
Owner SHAANXI UNIV OF SCI & TECH
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