Method for preparing spherical calcium carbonate by causticizing paper making green liquor

A calcium carbonate, green liquor technology, applied in the direction of calcium carbonate/strontium/barium, fibrous fillers, pigment-containing coatings, etc., can solve the problems of low whiteness of white mud, difficult separation, uneven particle distribution, etc. High whiteness, simple treatment process, and the effect of solving secondary pollution

Active Publication Date: 2008-01-30
SHANGHAI DONGSHENG NEW MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The main components of these solid particles are hydroxides or sulfides of Fe, Mn, Al, Mg, and silicon compounds. The compounds of Fe and Mn are colored impurities. If they are not separated, they will be entrained to white during the causticizing reaction. In the mud, the whiteness of the white mud is reduced; and if the silicon compound is not separated, CaSiO will be generated during the causticization reaction. 3 Entrained into the lime mud, it makes it difficult to filter and wash the white mud, and it also causes serious wear and tear on the papermaking equipment when the white mud is used as a paper-making filler and a pigment for paper coating.
In addition, the solid particles in the green liquor will be used as white mud (CaCO 3 ) seed crystals during formation, so that the generated white mud CaCO 3 Irregular particle shape, uneven particle distribution
White mud CaCO 3 The irregular shape of the particles will also lead to increased wear on the papermaking equipment; while the lime mud CaCO 3 In addition to being related to the impurity content, the whiteness is also related to the white mud CaCO 3 Particle shape is related to particle distribu

Method used

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  • Method for preparing spherical calcium carbonate by causticizing paper making green liquor
  • Method for preparing spherical calcium carbonate by causticizing paper making green liquor

Examples

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Example Embodiment

[0022] Example 1

[0023] At 7m 3 Add 5m to the stainless steel reactor 3 Contains Na 2 CO 3 6% of the clear green liquor, add 50kg of attapulgite with a fineness of 100 mesh to the clear green liquor, stir evenly, and then send the green liquor into the drum to a straight 400mm, the drum speed 3400r / min, and the separation factor is 2500. In the horizontal screw discharge centrifuge with a speed of 8r / min, the green mud is further removed by centrifugal separation, and the green liquor from the horizontal screw discharge centrifuge is clear and transparent purified green liquor.

[0024] Take 100 liters of purified green liquor, add 400 liters of water to dilute, and slowly add 10% ZnSO by weight to the diluted green liquor. 4 The solution was 22kg, the reaction time was 5 hours, and the reaction temperature was 10°C. Finally, a ZnS colloidal seed crystal with blue light was obtained.

[0025] Add 518 liters of seed crystals to 4900 liters of purified green liquor, and then send ...

Example Embodiment

[0026] Example 2

[0027] At 7m 3 Add 5m to the stainless steel reactor 3 Contains Na 2 CO 3 6% of the clear green liquor, add 100kg of attapulgite with a fineness of 500 mesh to the clear green liquor, stir evenly, and then send the green liquor into the drum with a diameter of 350mm, a drum speed of 3700r / min, and a separation factor of 2600. In the horizontal screw discharge centrifuge with a speed of 6r / min, the green mud is further removed by centrifugal separation, and the green liquor from the horizontal screw discharge centrifuge is clear and transparent purified green liquor. Take 50 liters of purified green liquor, add 250 liters of water to dilute, and slowly add 15% ZnSO to the diluted green liquor. 4 The solution was 10 kg, the reaction time was 4 hours, and the reaction temperature was 25° C. Finally, a ZnS colloidal seed crystal with blue light was obtained.

[0028] Add 308 liters of seed crystals to 4950 liters of purified green liquor, and then send the purified ...

Example Embodiment

[0029] Example 3

[0030] At 7m 3 Add 5m to the stainless steel reactor 3 Contains Na 2 CO 3 6% of the clarified green liquor, add 120kg of attapulgite with a fineness of 1500 mesh to the clarified green liquor, stir evenly, and then send the green liquor into the drum with a diameter of 300mm, a drum speed of 4200r / min, and a separation factor of 3000. In the horizontal screw discharge centrifuge with a speed of 2r / min, the green mud is further removed by centrifugal separation, and the green liquor from the horizontal screw discharge centrifuge is a clear and transparent purified green liquor. Take 150 liters of purified green liquor, add 600 liters of water to dilute, and slowly add 30% ZnSO to the diluted green liquor. 4 The solution was 25kg, the reaction time was 10 hours, and the reaction temperature was 28°C. Finally, a ZnS colloidal seed crystal with blue light was obtained.

[0031] Add 770 liters of seed crystals to 4850 liters of purified green liquor, and then send th...

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Abstract

The invention discloses a method to causticize and produce spherical calcium carbonate with papermaking green liquor and comprises the steps that: attapulgite is added in clear papermaking green liquor, green mature mud of which is removed, then is centrifugally separated to get purified green liquor, ZnSO4 solution is added drop by drop and is reacted to get solution containing ZnS crystal seed; the crystal seed is added to the purified green liquor, then Ca(OH)2 slurry is added drop by drop, reacted, filtered to get white mud calcium carbonate and white liquor; white mud calcium carbonate is cleaned to get purified white mud filter cake. The method of the invention well solves the secondary pollution problem of white mud, the treatment process is simple and quick, whiteness of the white mud CaCO3 obtained is high and the invention partly replaces American porcelain clay and calcined kaolin; besides, smoothness of paper pattern, glossiness of coating paper, surface strength, ink absorption and other differences are not large.

Description

technical field [0001] The invention relates to a method for purifying green liquor in the pulp and paper industry. Background technique [0002] Alkaline chemical pulp black liquor is extracted, evaporated and concentrated, and the melt obtained after burning is dissolved in dilute white liquor or water to form green liquor, the main component of which is sodium carbonate. In the process of causticization, lime is added to the green liquor, so that the sodium carbonate in the green liquor is converted into sodium hydroxide to form white liquor, and at the same time, the precipitated white mud is obtained. [0003] At present, lime mud produced by alkali pulping plants using wood as raw material is generally recovered by calcined lime method. However, a large amount of heavy oil and other fuels are generally used in the process of calcining recycled lime in lime mud, and the calcination process is relatively complicated, which makes The overall cost of lime obtained after c...

Claims

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Application Information

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IPC IPC(8): C01F11/18C09C1/02D21H19/38
Inventor 施晓旦王彦华
Owner SHANGHAI DONGSHENG NEW MATERIALS
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