CN109667189B - Preparation method of chrysanthemum-shaped light calcium carbonate filler - Google Patents
Preparation method of chrysanthemum-shaped light calcium carbonate filler Download PDFInfo
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- CN109667189B CN109667189B CN201710952768.2A CN201710952768A CN109667189B CN 109667189 B CN109667189 B CN 109667189B CN 201710952768 A CN201710952768 A CN 201710952768A CN 109667189 B CN109667189 B CN 109667189B
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/675—Oxides, hydroxides or carbonates
Abstract
The invention discloses a preparation method of chrysanthemum-shaped light calcium carbonate filler, which comprises the following steps: step one, adding calcium hydroxide fine slurry into a carbonization tower, adding a crystal form control agent, and uniformly mixing; step two, introducing kiln gas for carbonization, detecting the conductivity on line in the carbonization process, stopping introducing gas when the conductivity reaches the lowest, then increasing the conductivity by 0.3-0.5mS/cm, introducing gas again after 5-30 minutes, and stopping carbonization until the conductivity is increased to 0.7-1.0mS/cm again to obtain cooked slurry; and step three, adding a crystal form modifier into the cooked slurry, uniformly mixing, and removing impurities to obtain the chrysanthemum-shaped light calcium carbonate filler. The light calcium carbonate filler prepared by the invention has higher specific surface area and sediment volume. The filler is used for papermaking filling, can effectively improve the indexes of the paper such as bulk, opacity, whiteness and the like, can improve the retention rate of the filler, saves the fiber consumption, and thus reduces the papermaking cost.
Description
Technical Field
The invention relates to the field of papermaking filler preparation, in particular to a preparation method of chrysanthemum flower-shaped light calcium carbonate filler.
Background
Light calcium carbonate is one of the most commonly used fillers in the paper industry, and the use of fillers in place of paper making fibers can reduce production costs and, in addition, can improve the optical properties, printing properties, and appearance of paper. The light calcium carbonate is used as an important inorganic chemical raw material, and can be in different crystal shapes such as cubes, spindles, needles, chains, sheets and the like due to different preparation processes. The light calcium carbonate produced by the common carbonization method is mostly spindle-shaped or needle-rod-shaped, and has wide particle size distribution range, coarse particles, poor dispersibility and poor covering power. The chrysanthemum-shaped light calcium carbonate takes the crystal seeds as the core and is arranged in a radial growth mode, and the structure enables the chrysanthemum-shaped light calcium carbonate to have high light scattering capacity, so that the whiteness and the opacity of paper can be remarkably improved. The chrysanthemum-shaped light calcium carbonate also has a higher sinking body, and the chrysanthemum-shaped light calcium carbonate can endow paper with better bulk, reduce the using amount of paper pulp and reduce the cost.
CN102502749A discloses a method for preparing rose-shaped calcium carbonate by using low-grade limestone. The invention prepares lime by using limestone with lower calcium carbonate content after long-time calcination, and prepares rosette precipitated calcium carbonate by adding a crystal form control agent. In the invention, the limestone is calcined for a long time, a plurality of whitening agents are used, one or two of ammonium phosphate and citrate are used as crystal form control agents, and a dispersing agent is also used, so that the process is complex and the production cost is high.
CN105800657A discloses a preparation method of rosette precipitated calcium carbonate, which comprises the steps of digesting burnt lime and slaking water added with a compound additive according to a ratio of 1:5-10, filtering and deslagging by a 60-120 mesh vibrating screen, adding a crystal form control agent after diluting the prepared calcium hydroxide emulsion with water, then sending the calcium hydroxide emulsion into a reaction tower, introducing kiln gas for carbonization until the pH value is less than 7.5, stopping carbonization, and dehydrating, drying, crushing and screening the precipitated calcium carbonate suspension to obtain the rosette precipitated calcium carbonate. In the invention, various monosaccharides and polysaccharides are required to be added to prepare water for digestion, and a crystal form control agent is also required to be added to the seminal plasma.
At present, although the process for industrially preparing the similar light calcium carbonate product exists, the process for preparing the light calcium carbonate product has important significance in seeking for a newer preparation process, simplifying the process flow and reducing the production cost.
Disclosure of Invention
The invention aims to provide a preparation method of chrysanthemum-shaped light calcium carbonate filler, which aims to solve the defects in the background art.
The invention is realized by the following technical scheme:
a preparation method of chrysanthemum-shaped light calcium carbonate filler comprises the following steps:
step one, adding calcium hydroxide fine slurry into a carbonization tower, adding a crystal form control agent, and uniformly mixing;
secondly, introducing kiln gas for carbonization, detecting the conductivity on line in the carbonization process, stopping introducing gas when the conductivity reaches the lowest value and then increasing the conductivity by 0.3-0.5mS/cm, introducing gas after 5-30 minutes until the conductivity is increased to 0.7-1.0mS/cm, and stopping carbonization to obtain cooked slurry;
and step three, adding a crystal form modifier into the cooked slurry, uniformly mixing, and removing impurities to obtain the chrysanthemum-shaped light calcium carbonate filler.
As a preferred technical scheme, the crystal form control agent is citric acid, the addition amount of the crystal form control agent is 0.1-3 per mill of the dry weight of the light calcium carbonate, and the concentration of the crystal form control agent is 20-30 wt%. Dry refers to the weight without water.
As a preferred technical scheme, the crystal form modifier is phosphoric acid, and the addition amount of the crystal form modifier is 0.2-0.5% of the dry weight of the light calcium carbonate.
As a preferred technical scheme, the calcium hydroxide seminal plasma is prepared by adopting the following method:
step one, calcining: calcining limestone to obtain lime;
step two, digestion: digesting the lime obtained in the step (1) with hot water to obtain coarse slurry;
step three, impurity removal: after the coarse pulp is concentrated, the fine pulp is obtained through vibration screening and suspension separation and impurity removal;
step four, aging: and aging the fine slurry to obtain the calcium hydroxide fine slurry.
As a preferred technical scheme, the calcination conditions in the first step are as follows: an automatic mechanical vertical steel kiln is adopted, the size of limestone is 30-60mm, the coal-stone ratio is 75-95kg/T limestone, the calcining temperature is controlled between 950 and 1050 ℃, and the calcining time is 15-30 h.
As a preferred technical scheme, the digestion conditions in the second step are as follows: the mass ratio of lime to water is 1:5-1:7, the digestion temperature is 70-90 ℃, and the slaking rate is more than or equal to 90%.
As a preferred technical scheme, the impurity removal in the third step refers to adjusting the concentration of the coarse pulp to 15-17 wt%, firstly passing through a 100-mesh sieve, and then removing impurities through a hydrocyclone separator.
As a preferred technical scheme, the aging conditions in the fourth step are as follows: the aging time is 12-24 hours, and the temperature is 35-45 ℃.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the light calcium carbonate filler particles prepared by the method are in a chrysanthemum shape, and have high specific surface area (9-15 square meters per gram) and sinking bodies (3-5 ml/g).
2. The chrysanthemum-shaped light calcium carbonate filler obtained by the method is used for papermaking filling, can effectively improve the indexes of paper such as bulk, opacity, whiteness and the like, can improve the retention rate of the filler, saves the fiber consumption, and thus reduces the papermaking cost.
3. The method has relatively simple process, uniform particle size distribution and stable quality of the product by detecting the conductivity on line and automatically controlling the reaction process, and realizes industrial production.
Drawings
Fig. 1 is an electron micrograph of the chrysanthemum-like light calcium carbonate filler prepared in example 1.
Fig. 2 is an electron micrograph of the chrysanthemum-like light calcium carbonate filler prepared in example 2.
Fig. 3 is an electron micrograph of the chrysanthemum-like light calcium carbonate filler prepared in example 3.
FIG. 4 is an electron micrograph of a conventional precipitated calcium carbonate filler prepared according to example 4.
Detailed Description
The invention is illustrated below by means of specific examples, without being restricted thereto.
Example 1
An automatic mechanical vertical steel kiln is adopted, 30-60mm limestone is selected, the coal-stone ratio is 80kg/T limestone, the calcining temperature is controlled to be 1000 ℃, and the calcining time is 25 hours. And (3) putting lime into hot water at 80 ℃ for digestion, wherein the mass ratio of the lime to the water is 1: 6. Adding water into the digested coarse pulp to adjust the concentration to 15%, sieving with a 100-mesh sieve, and removing impurities with a hydrocyclone to obtain refined pulp. After the fine pulp is aged for 24 hours, the temperature is reduced to 45 ℃. And (3) putting the fine slurry into a carbonization tower, adding 1 per mill of citric acid (dried relative to PCC) (with the concentration of 30 percent) serving as a crystal form control agent, and uniformly stirring. And (4) introducing gas for carbonization, wherein the concentration of the kiln gas is 30%, continuously detecting the conductivity on line in the carbonization process, and stopping introducing gas when the conductivity reaches the lowest value and then rises by 0.5 mS/cm. And re-aerating after 5 minutes until the conductivity rises to 0.7mS/cm again to finish carbonization. Adding phosphoric acid as crystal modifier into the cooked slurry, adding 0.3% phosphoric acid (solid/solid) (3 Kg/ton PCC), and stirring uniformly. And removing impurities through a 325-mesh sieve to finally obtain the chrysanthemum flower-shaped light calcium carbonate slurry. The solid content of the product is detected to be 19.1 percent, the pH value is 7.18, the American particle size D90 is 4.102 mu m, the D50 is 1.680 mu m, the specific surface area is 9.2 square meters per gram, and the weight of the product is 3.43 ml/g. The product is shown in figure 1 by scanning electron microscopy analysis.
Example 2
An automatic mechanical vertical steel kiln is adopted, limestone with the size of 30-60mm is selected, the coal-stone ratio is 80kg/T limestone, the calcining temperature is controlled to be 1000 ℃, and the calcining time is 25 hours. And (3) putting lime into hot water at 80 ℃ for digestion, wherein the mass ratio of the lime to the water is 1: 6. Adding water into the digested coarse pulp to adjust the concentration to 15%, sieving with a 100-mesh sieve, and removing impurities with a hydrocyclone to obtain refined pulp. After the seminal plasma is aged for 24 hours, the temperature is reduced to 40 ℃. And (3) putting the fine slurry into a carbonization tower, adding 1.5 per mill of citric acid (relative to dry PCC) (with the concentration of 30 percent) serving as a crystal form control agent, and uniformly stirring. And (4) introducing gas for carbonization, wherein the concentration of the kiln gas is 30%, continuously detecting the conductivity on line in the carbonization process, and stopping introducing gas when the conductivity reaches the lowest value and then rises by 0.5 mS/cm. After 5 minutes, the atmosphere was again vented until the conductivity rose by 0.7mS/cm, and carbonization was terminated. Adding phosphoric acid as crystal modification agent into the cooked slurry, wherein the addition amount of the phosphoric acid is 0.3 percent (solid/solid) (3 Kg/ton PCC), and uniformly stirring. And removing impurities through a 325-mesh sieve to finally obtain the chrysanthemum flower-shaped light calcium carbonate slurry. The solid content of the product is detected to be 19.2 percent, the pH value is 7.50, the American particle size D90 is 3.240 mu m, the D50 is 1.312 mu m, the specific surface area is 11.4 square meters per gram, and the weight of the product is 4.20 ml/g. The product was analyzed by scanning electron microscopy as shown in FIG. 2.
Example 3
An automatic mechanical vertical steel kiln is adopted, limestone with the size of 30-60mm is selected, the coal-stone ratio is 80kg/T limestone, the calcining temperature is controlled to be 1000 ℃, and the calcining time is 25 hours. And (3) putting lime into hot water at 80 ℃ for digestion, wherein the mass ratio of the lime to the water is 1: 6. Adding water into the digested coarse pulp to adjust the concentration to 15%, sieving with a 100-mesh sieve, and removing impurities with a hydrocyclone to obtain refined pulp. After the seminal plasma is aged for 24 hours, the temperature is reduced to 35 ℃. And (3) putting the fine slurry into a carbonization tower, adding 2 per mill of citric acid (dried relative to PCC) (with the concentration of 30 percent) serving as a crystal form control agent, and uniformly stirring. And (4) introducing gas for carbonization, wherein the concentration of the kiln gas is 30%, continuously detecting the conductivity on line in the carbonization process, and stopping introducing gas when the conductivity reaches the lowest value and then rises by 0.5 mS/cm. After 5 minutes, the atmosphere was again vented until the conductivity rose by 0.7mS/cm, and carbonization was terminated. Adding phosphoric acid as crystal modifier into the cooked slurry, adding 0.3% phosphoric acid (solid/solid) (3 Kg/ton PCC), and stirring uniformly. Removing impurities through a 325-mesh sieve to finally obtain the chrysanthemum flower-shaped light calcium carbonate slurry. The solid content of the product is detected to be 19.0 percent, the pH value is 7.66, the American particle size D90 is 2.603 mu m, the D50 is 1.108 mu m, the specific surface area is 13.8 square meters per gram, and the weight of the product is 4.78 ml/g. The product is analyzed by scanning electron microscopy as shown in figure 3.
Example 4
An automatic mechanical vertical steel kiln is adopted, 30-60mm limestone is selected, the coal-stone ratio is 80kg/T limestone, the calcining temperature is controlled to be 1000 ℃, and the calcining time is 25 hours. And putting lime into hot water at the temperature of 80 ℃ for digestion, wherein the mass ratio of the lime to the water is 1: 6. Adding water into the digested coarse pulp to adjust the concentration to 15%, sieving with a 100-mesh sieve, and removing impurities with a hydrocyclone to obtain refined pulp. After the seminal plasma is aged for 24 hours, the temperature is reduced to 35 ℃. And (3) throwing the fine slurry into a carbonization tower, adding no crystal form control agent, and uniformly stirring. And (4) introducing gas for carbonization, wherein the concentration of the kiln gas is 30%, continuously detecting the conductivity on line in the carbonization process, and stopping introducing gas when the conductivity reaches the lowest value and then rises by 0.5 mS/cm. And (5) aerating after 5 minutes until the conductivity rises to 0.7mS/cm again, and ending carbonization without adding a crystal form modifier. And removing impurities through a 325-mesh sieve to finally obtain the common light calcium carbonate slurry. The solid content of the product is detected to be 19.4 percent, the pH value is 7.85, the American particle size D90 is 4.496 mu m, the D50 is 2.166 mu m, the specific surface area is 6.0 square meter/g, and the weight is 2.80 ml/g. The product was analyzed by scanning electron microscopy as shown in FIG. 4.
Paper filling experiments:
the chrysanthemum light calcium sample in example 1 and the common light calcium sample in example 4 were selected to carry out a paper filling experiment:
needle blade pulp (40) 0 SR): broad leaf pulp (38) 0 SR) 20: 80 (dry/dry) degree of kowtows 38 0 SR wet weight 3.0g
The papermaking process comprises the following steps: pulp (65%) + AKD (20Kg/t paper) + Filler (35%) + CPAM (200ppm)
Design papermaking ration of 80g/m 2 Stirring weighed paper pulp for 1 minute, adding AKD and filler, stirring for 1 minute, adding CPAM, stirring for 1 minute, taking off, making into sheet with LABTECH73-62 semiautomatic paper former, and making into LAB sheetAnd (4) squeezing by a TECH 73-50 standard paper sheet squeezer, naturally drying, and detecting indexes such as bulk, opacity, whiteness, retention rate and the like of the paper sample.
The detection data are shown in Table 1:
TABLE 1
According to the invention, limestone is calcined, then lime is subjected to a series of processes such as digestion, impurity removal, aging, regulation and control, carbonization, regulation and control again and impurity removal, citric acid is added into refined slurry to serve as a crystal form control agent, phosphoric acid is added into cooked slurry to serve as a crystal form modifier, and the reaction process is automatically controlled by detecting the conductivity on line, so that the chrysanthemum flower-shaped light calcium carbonate slurry is finally obtained. The light calcium carbonate filler prepared by the invention is chrysanthemum-shaped, has higher specific surface area and settling volume compared with the common filler light calcium, is used for filling in papermaking, can effectively improve the indexes of bulk, opacity, whiteness and the like of paper sheets, can improve the retention rate of the filler, saves the fiber consumption and further reduces the papermaking cost.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (6)
1. A preparation method of chrysanthemum-shaped light calcium carbonate filler is characterized by comprising the following steps:
step one, adding calcium hydroxide fine slurry into a carbonization tower, adding a crystal form control agent, and uniformly mixing;
step two, introducing kiln gas for carbonization, detecting the conductivity on line in the carbonization process, stopping introducing gas when the conductivity reaches the lowest, then increasing the conductivity by 0.3-0.5mS/cm, introducing gas again after 5-30 minutes, and stopping carbonization until the conductivity is increased to 0.7-1.0mS/cm again to obtain cooked slurry;
adding a crystal form modifier into the cooked slurry, uniformly mixing, and removing impurities to obtain the chrysanthemum-shaped light calcium carbonate filler;
the crystal form control agent is citric acid, the addition amount of the crystal form control agent is 0.1-3 per mill of the dry weight of the light calcium carbonate, and the concentration of the crystal form control agent is 20-30 wt%; the crystal modification agent is phosphoric acid, and the addition amount of the crystal modification agent is 0.2-0.5% of the dry weight of the light calcium carbonate.
2. The method of claim 1, wherein the calcium hydroxide concentrate is prepared by:
step one, calcining: calcining limestone to obtain lime;
step two, digestion: digesting the lime obtained in the step one with hot water to obtain coarse pulp;
step three, impurity removal: after the coarse pulp is concentrated, the fine pulp is obtained through vibration screening and suspension separation and impurity removal;
step four, aging: and aging the fine slurry to obtain the calcium hydroxide fine slurry.
3. The method of claim 2, wherein the calcination conditions in step one are: an automatic mechanical vertical steel kiln is adopted, the size of limestone is 30-60mm, the coal-stone ratio is 75-95kg/t limestone, the calcining temperature is controlled between 950 ℃ and 1050 ℃, and the calcining time is 15-30 h.
4. The method of claim 2, wherein the digestion conditions in step two are: the mass ratio of lime to water is 1:5-1:7, the digestion temperature is 70-90 ℃, and the slaking rate is more than or equal to 90%.
5. The method of claim 2, wherein the removing impurities in step three comprises adjusting the concentration of the brown stock to 15-17 wt%, passing through a 100 mesh sieve, and removing impurities in a hydrocyclone.
6. The method of claim 2, wherein the aging conditions in step four are: the aging time is 12-24 hours, and the temperature is 35-45 ℃.
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| CN102432054A (en) * | 2011-09-28 | 2012-05-02 | 建德市云峰碳酸钙有限公司 | Method for producing light calcium carbonate slurry and light calcium carbonate paste |
| CN102502748B (en) * | 2011-10-20 | 2014-06-11 | 福建省万旗非金属材料有限公司 | Microwave method for preparing rose-shaped calcium carbonate |
| CN103451992B (en) * | 2013-01-10 | 2015-08-19 | 湖南皓志科技股份有限公司 | A kind of preparation method of super-hydrophobic, self-cleaning papermaking coating |
| CN105800657B (en) * | 2016-04-22 | 2018-06-29 | 广西合山东来化工科技有限公司 | A kind of preparation method of rose-shaped winnofil |
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