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Dealkalization and purification method used in production of precipitated calcium carbonate

A technology of precipitated calcium carbonate and production process, which is applied in the direction of calcium carbonate/strontium/barium, etc., and can solve problems such as the inability to stabilize the pH value of light calcium carbonate products and the inability to improve the brightness of calcium carbonate products

Inactive Publication Date: 2015-08-19
李广
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The object of the present invention is to provide a kind of dealkalization and impurity removal purification method in the preparation production process of precipitated calcium carbonate, has solved traditional lime mud pH value stabilization process and adopts flue gas carbon dioxide (CO 2 ), oxalic acid and phosphoric acid reduce the pH value, but cannot stabilize the pH value of the light calcium carbonate product, and cannot improve the brightness of the calcium carbonate product. The technical solution of the present invention can effectively dealkalize and reduce and stabilize the light calcium carbonate regeneration The PH value of calcium carbonate products can effectively remove metal ion impurities, including iron ion Fe, from raw lime and sodium carbonate in causticizing lime mud by using the intermediate substances produced during the removal of residual alkali. 3+ , Fe 3+ , Magnesium ion Mg 2+ , manganese ions and other metal ions to improve the brightness (whiteness) and purity of the product of light calcium carbonate regenerated from lime mud

Method used

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  • Dealkalization and purification method used in production of precipitated calcium carbonate

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Effect test

Embodiment 1

[0043] (1) 10kg of causticizing white mud calcium carbonate system is concentrated to 20wt% (solid content), and its residual alkali content is measured to be 1.0wt%, and the white mud brightness is 86%, and the pH value exceeds 14;

[0044] (2) Then add citric acid solution with a mass concentration of 5%, react and stir for 20 minutes to make a mixed solution; the amount of citric acid solution is 3.56L;

[0045] (3) Send the mixed solution in step (2) into a fully sealed upflow reactor, control the reaction temperature at 25°C, react and stir for 20 minutes;

[0046] (4) After the reaction is completed, the mixed solution is sent to the solid-liquid separation device for dilution and washing with water, and then goes down to the process for particle size control.

[0047] Measurement results after the reaction: the pH value of the calcium carbonate product is 8.02, the purity is 94.61%, the brightness is 88.39%; the residual alkali content is 0.02wt%.

Embodiment 2

[0049] (1) 10kg of causticizing white mud calcium carbonate system is adjusted to 25wt% (solid content), and its residual alkali content is measured to be 0.8wt%, and the white mud brightness is 86%, and the pH value exceeds 14;

[0050] (2) Then add citric acid solution with a mass concentration of 5%, react and stir for 10 minutes to make a mixed solution; the amount of citric acid solution is 2.79L;

[0051] (3) Send the mixed solution in step (2) into a fully sealed upflow reactor, control the reaction temperature at 30°C, react and stir for 30 minutes;

[0052] (4) After the reaction is completed, the mixed solution is sent to the solid-liquid separation device for dilution and washing with water, and then goes down to the process for particle size control.

[0053] Measurement results after reaction: the pH value of the calcium carbonate product is 8.11, the purity is 94.32%, the brightness is 88.56%; the residual alkali content is 0.01wt%.

Embodiment 3

[0055] (1) 10kg of causticizing white mud calcium carbonate system is concentrated to 35wt% (solid content), and its residual alkali content is measured to be 0.7wt%, and the white mud brightness is 85%, and the pH value exceeds 14;

[0056] (2) Then add citric acid solution with a mass concentration of 5%, react and stir for 25 minutes to make a mixed solution; the amount of citric acid solution is 2.39L;

[0057] (3) Send the mixed solution in step (2) into a fully sealed upflow reactor, control the reaction temperature at 35°C, react and stir for 50 minutes;

[0058] (4) After the reaction is completed, the mixed solution is sent to the solid-liquid separation device for dilution and washing with water, and then goes down to the process for particle size control.

[0059] Measurement results after the reaction: the pH value of the calcium carbonate product is 7.83, the purity is 95.13%, the brightness is 88.25%; the residual alkali content is 0.01wt%.

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Abstract

The invention provides a dealkalization and purification method used in the production of precipitated calcium carbonate. The method comprises the following successive steps: (1) adding water into a calcium carbonate system produced by causticization of white mud to obtain a calcium carbonate emulsion with solid content of 5 to 45 wt%; (2) adding a dealkalization agent with a mass concentration of 0.1 to 10% into the calcium carbonate emulsion and carrying out reaction and stirring so as to prepare mixed liquor; (3) delivering the mixed liquor prepared in the step (2) to a hermetically sealed upflow-type reaction vessel and carrying out reaction and stirring; and (4) after completion of the reaction, delivering the mixed liquor into a solid-liquid separator, diluting and washing the mixed liquor with water and then carrying out granularity control; wherein the dealkalization agent used in the step (2) is one selected from the group consisting of citric acid, formic acid or malic acid. The method can stabilize the pH value of the calcium carbonate system and improve product brightness and purity.

Description

technical field [0001] The invention relates to the field of precipitated calcium carbonate production, in particular to the field of regeneration and reuse of lime mud calcium carbonate recovered from alkali in papermaking chemical industry. Background technique [0002] In the alkali recovery process of the paper industry, the green liquor formed by dissolving the melted black liquor after burning in dilute white liquor or water is mainly composed of sodium carbonate, or sodium carbonate and sodium sulfide (sulfate method), and contains a small amount of green liquor. Metal impurities such as divalent iron salts and divalent manganese salts. The green liquor is causticized with lime to recover sodium hydroxide, and the by-product precipitated calcium carbonate white mud contains part of NaOH, Na 2 CO 3 , Ca(OH) 2 and other residual alkali, as well as metal impurities such as iron and manganese. The residual alkali in the described calcium carbonate white mud is general...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F11/18
Inventor 李广
Owner 李广
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