KR102567345B1 - Method of manufacturing calcium carbonate - Google Patents

Abstract

According to the present invention, using selective mining and selective beneficiation, preparing an ore having a purity of 96% or more of CaCO3 for firing; A calcination step of making quicklime by extending the low-temperature calcination and residence time to completely decarboxylate and calcine the residual CO2 to 1.0% or less; a hydration step in which quicklime is reacted with water to form a calcium hydroxide suspension; and a carbonation step of producing calcium carbonate by blowing CO2 gas into the calcium hydroxide suspension to react.
In addition, in the hydration step, an additive is added to delay hydration to make calcium hydroxide particles more fine to improve whiteness, and the calcium hydroxide slurry treated with the additive is added using a screen and a magnet to improve the whiteness. A method for producing precipitated calcium carbonate is disclosed that undergoes a hydration refinement process to select, and in the carbonation step, flotation is further performed to further improve the whiteness of the calcium carbonate slurry made in the carbonation step. .

Description

Method for producing precipitated calcium carbonate {METHOD OF MANUFACTURING CALCIUM CARBONATE}

The present invention relates to a method for producing precipitated calcium carbonate, and more particularly, to improve the whiteness while finening calcium hydroxide particles by adding an additive to delay hydration in the hydration process of making calcium hydroxide, and Carbonation process Ca(OH) ₂ + CO ₂ → CaCO ₃ + H ₂ It relates to a method for producing precipitated calcium carbonate, characterized in that the precipitated calcium carbonate (PCC) slurry synthesized through O is subjected to an additional whiteness improvement process through floatation.

Limestone consists of quicklime (calcium oxide), slaked lime (calcium hydroxide), ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), etc., depending on the processing stage, and the price varies greatly depending on the degree of processing. is showing

Here, precipitated calcium carbonate is a high value-added material field because shape control and particle unit control are possible through chemical processing. In Figure 1, it is shown that precipitated (hard) calcium carbonate is classified. Recently, the demand for highly functional and high-quality limestone-based products is rapidly increasing in domestic and foreign automobile material industries, high-functional plastic material industries, paper ship industries, and construction material industries. Precipitated calcium carbonate is in the limelight as a highly functional material for manufacturing composite PP for automobiles, and research is being conducted worldwide.

Since the physical properties of composite PP are determined by the particle shape of the material, in order for precipitated calcium carbonate to be used as a material for manufacturing composite PP, the development of synthesis technology for precipitated calcium carbonate particle size and shape control must be preceded.

In relation to this, Republic of Korea Patent No. 10-1256807 (registered on April 16, 2013, title of invention: quicklime molded body using limestone powder with low utilization and its manufacturing method and light calcium carbonate using the same {the limestone forming materials using waste lime powder) and a method of therof}), "In the present invention, limestone of 20 mm or less, which is generated during the crushing process of limestone and discarded or used as a low-cost cement raw material, is made into powder, and high-quality lime is obtained through molding and firing processes. It is disclosed about "manufacturing and firing a molded body using limestone powder, which is recycled as a resource and improves added value, and how to use it as a raw material for precipitated calcium carbonate."

In addition, according to Korean Patent Publication No. 10-2014-0087330 (published on July 9, 2014, title of invention: Method of manufacturing calcium carbonate from calcium silicate by-products}), "As a method for producing precipitated calcium carbonate, the first step is to obtain calcium chloride and ammonium hydroxide by adding calcium silicate-based by-products to an aqueous ammonium chloride solution; the second step to obtain an aqueous calcium chloride solution and ammonia by heating the calcium chloride and the ammonium hydroxide A method for producing precipitated calcium carbonate comprising a third step of adding sodium carbonate to the aqueous calcium chloride solution to obtain precipitated calcium carbonate and an aqueous sodium chloride solution; and a fourth step of recovering precipitated calcium carbonate from the aqueous sodium chloride solution. there is.

However, in the above patent documents, additives are added to the hydration process of making calcium hydroxide to delay hydration, thereby improving the whiteness while finening calcium hydroxide particles, and screening the additive-treated calcium hydroxide slurry using a screen and a magnet Synthetic calcium carbonate (PCC) synthesized through the carbonation process Ca(OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O : Precipitated Calcium Carbonate, hard coal) A method for producing precipitated calcium carbonate, that is, a technique such as the present invention, characterized in that the slurry is subjected to an additional whiteness improvement process through floatation, has not been disclosed at all.

Republic of Korea Patent No. 10-1256807 (registered on April 16, 2013, title of invention: Quicklime formed body using limestone powder with low utilization and its manufacturing method and light calcium carbonate using the same {the limestone forming materials using waste lime powder and a method of therof}) Republic of Korea Patent Publication No. 10-2014-0087330 (published on July 9, 2014, title of invention: Method of manufacturing calcium carbonate from calcium silicate by-products})

The present invention was created to solve the above-mentioned problems, and an object of the present invention is to provide a synthesis technique for synthesizing precipitated calcium carbonate based on domestic limestone, reducing impurities, and having excellent particle size and shape control.

Specifically, the present invention adds an additive to the hydration process of making calcium hydroxide to delay hydration to fine the calcium hydroxide particles while improving the whiteness, and screening the additive-treated calcium hydroxide slurry using a screen and a magnet _Synthetic calcium _{carbonate ( PCC} : It is an object of the present invention to provide a method for producing precipitated calcium carbonate, characterized in that precipitated calcium carbonate (hard coal) slurry is subjected to an additional whiteness improvement process through floatation.

Method for producing precipitated calcium carbonate according to the present invention for achieving the above object, using selective mining and selective beneficiation, preparing ore having a purity of 96% or more of CaCO3 for firing; A calcination step of making quicklime by extending the low-temperature calcination and residence time to completely decarboxylate and calcine the residual CO2 to 1.0% or less; a hydration step of making a calcium hydroxide suspension by reacting the quicklime with water; and a carbonation step of making calcium carbonate by reacting by blowing CO2 gas into the calcium hydroxide suspension.

In addition, in the hydration step, an additive is added to delay hydration to make calcium hydroxide particles finer to improve whiteness.

In addition, in the hydration step, a hydration refinement process in which the calcium hydroxide slurry treated with the additive is screened using a screen and a magnet to improve whiteness is further included.

In addition, in the carbonation step, flotation is further performed to further improve the whiteness of the calcium carbonate slurry produced in the carbonation step.

In addition, the additive is black sugar, and the black sugar is added at a rate of 0.5% to 1% compared to the quicklime, and the additive causes impurities in the quicklime to aggregate, so that the hydration refinement process It is classified with a 325 mesh screen to remove agglomerated impurities to improve whiteness.

In addition, after the carbonation step, adding a flotation agent; further comprising,

The flotation agent is composed of a first flotation agent of 1% relative to the quicklime and a second flotation agent of 1% relative to the quicklime, and the first flotation agent is 35% by weight or more and less than 40% by weight of 2-ethylhexanol. ; greater than or equal to 35% but less than 40% by weight of distillates (petroleum), distillates (petroleum), hydrotreated light; And 25% by weight or more and less than 30% by weight of N-oleyl 1,3-diaminopropane, wherein the second flotation agent comprises 25% to 50% by weight of alcohol; 25% to 50% by weight of distillates (petroleum), hydrotreated light; and 25% to 50% by weight of a fatty amine derivative.

In addition, in the case of making spindle-shaped precipitated calcium carbonate, in the hydration step, 1,000 liters of water is added at a rate of 200 kg of the quicklime, the water is raised from 18 degrees Celsius to 55 degrees Celsius, and in the carbonation step, The water is raised from 40 degrees Celsius to 60 degrees Celsius, and in the case of making cubic precipitated calcium carbonate, in the hydration step, 1,000 liters of water is added at a rate of 100 kg of quicklime, groundwater heat exchange through a double jacket If there is no, the water rises from 18 degrees Celsius to 36 degrees Celsius, and the water is limited so that it does not rise above 30 degrees Celsius by using groundwater heat exchange through a double jacket, and in the carbonation step, groundwater heat exchange through a double jacket If there is no, the water rises from 25 degrees Celsius to 43 degrees Celsius, but is limited so that it does not rise above 35 degrees Celsius by using groundwater heat exchange through a double jacket.

According to the method for producing precipitated calcium carbonate according to the present invention,

First, the domestic ecosystem currently imports and operates high-color limestone and high-color quicklime. The present invention uses domestic raw materials with lower whiteness than user requirements, and goes through a whiteness improvement process to meet the high requirements of users. It is possible to manufacture

Second, whiteness can be improved through the addition of black sugar (additive) that aggregates impurities that interfere with whiteness improvement and through a 325 mesh screen that classifies impurities aggregated due to the additive.

Third, it goes through a hydration refinement process in which a permanent magnet is used to sort it out. In the case of such a charity (sorting with a magnet or magnetic force), the average whiteness is 0.6 compared to the case where charity is not used. can improve.

Fourth, by further performing flotation, it is possible to improve the average whiteness of 1.4 compared to the case of flotation.

Fifth, after the carbonation step, the whiteness may be improved by adding the first flotation agent and the second flotation agent according to the present invention.

Figure 1 shows the classification of precipitated (hard) calcium carbonate.
Figure 2 schematically shows a system to which the method for producing precipitated calcium carbonate according to the present invention is applied.
3 is a SEM photograph of spindle-shaped precipitated calcium carbonate prepared according to the method for preparing precipitated calcium carbonate according to the present invention.
4 is a SEM photograph of cubic precipitated calcium carbonate prepared according to the method for preparing precipitated calcium carbonate according to the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be construed as being limited to the usual or dictionary meaning, and the inventor appropriately uses the concept of the term in order to explain his/her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical spirit of the present invention.

Therefore, since the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, various alternatives may be used at the time of this application. It should be understood that there may be equivalents and variations.

In the method for producing precipitated calcium carbonate according to the present invention, additives are added to the hydration process of making calcium hydroxide to delay hydration, thereby improving the whiteness while finening the calcium hydroxide particles, and adding the additive-treated calcium hydroxide slurry to a screen and a magnet. Synthetic carbonic acid synthesized through the carbonation process Ca(OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O by using the calcium hydroxide slurry that has gone through the hydration and refinement process selected using Calcium (PCC: Precipitated Calcium Carbonate, hard coal) slurry is characterized by undergoing an additional whiteness improvement process through floatation.

Figure 1 shows the classification of precipitated (hard) calcium carbonate. Hereinafter, with reference to FIG. 1, the manufacturing method of precipitated calcium carbonate is demonstrated. The method for producing precipitated calcium carbonate according to the present invention consists of an ore preparation step, a calcination step, a hydration step, a carbonation step, and a floatation agent addition step.

The ore preparation step is a step of preparing ore having a purity of 96% or more of CaCO ₃ for calcining using selective mining and selective beneficiation.

Due to the manufacturing characteristics of synthetic calcium carbonate, there is a large difference in product quality level between manufacturers, and a large difference in unit sales price according to quality. The quality of the secondary and tertiary processed products is mostly determined by the age of limestone, which is ore, and when there are many impurities in the ore, it is expensive to remove impurities in the secondary and tertiary processes, making it easy to manufacture synthetic calcium carbonate. It is preferable to develop ore, selectively mine and selectively beneficiate, and use raw ore with a purity of CaCO3 of 96% or more for firing.

The calcination step is a step of making quicklime by calcination at a low temperature (1000 degrees Celsius to 1100 degrees Celsius) and extending the residence time, completely decarboxylating and burning the residual CO ₂ to 1.0% or less. Low-temperature firing is low-temperature firing compared to high-temperature firing, and the residence time for firing should be extended compared to high-temperature firing. It is fired while staying in time.

Next, in the hydration step, quicklime is reacted with water to form a calcium hydroxide suspension. In this hydration step, an additive is added to delay hydration to make the calcium hydroxide particles finer to improve whiteness. Here, the whiteness index (WI) represents the degree of whiteness of an object, and the value of the whiteness decreases as the distance from 100, which is ideal whiteness, decreases.

Regarding the hydration process, it is a process of reacting quicklime with water to make a calcium hydroxide suspension. It is a process of adjusting the particle size and shape of calcium hydroxide according to temperature, concentration, stirring, and aging conditions, and removing impurities by sieving and magnetic force. do. Here, the impurities are pyrite, graphite, etc., and whiteness is improved by removing these impurities.

Here, the additive is black sugar, and this black sugar is added at a rate of 0.5% to 1% compared to quicklime. The additive causes impurities in the quicklime to aggregate, and the whiteness is improved by removing the aggregated impurities by classifying with a 325 mesh screen in the hydration refining process. That is, whiteness can be improved through the addition of black sugar (additive) that aggregates impurities that interfere with whiteness improvement and through a 325 mesh screen that classifies impurities aggregated due to the additive.

Below is a table showing the difference in whiteness between adding and not adding black sugar at the hydration stage. On average, it can be seen that the whiteness increased by 2.5.

In addition, in the hydration step, a hydration refinement process in which the calcium hydroxide slurry treated with the additive is screened using a screen and a magnet to improve whiteness is further included. The following is a comparison between the case of charity (magnet, magnetic sorting) and the case without after the hydration step. On average, it can be seen that the whiteness increased by 0.6.

Next, the carbonation step is a step of making calcium carbonate by reacting by blowing CO ₂ gas into the calcium hydroxide suspension. A synthetic calcium carbonate (PCC: Precipitated Calcium Carbonate, hard coal) slurry is prepared through a carbonation process, that is, Ca(OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O.

In this carbonation step, flotation is further performed to further improve the whiteness of the calcium carbonate slurry produced in the carbonation step. The following shows the difference in whiteness with and without flotation. On average, it can be seen that the whiteness increased by 1.4.

Next, after the carbonation step described above, a step of adding a flotation agent may be further included. The flotation agent consists of a first flotation agent of 1% relative to quicklime and a second flotation agent of 1% relative to the quicklime.

The first flotation agent comprises 35% by weight or more and less than 40% by weight of 2-ethylhexanol; greater than or equal to 35% but less than 40% by weight of distillates (petroleum), distillates (petroleum), hydrotreated light; and 25% by weight or more and less than 30% by weight of N-oleyl 1,3-diaminopropane.

The second flotation agent comprises 25% to 50% by weight of an alcohol; 25% to 50% by weight of distillates (petroleum), hydrotreated light; and 25% to 50% by weight of a fatty amine derivative.

In addition, in the case of making spindle-shaped precipitated calcium carbonate, in the above-mentioned hydration step, 1,000 liters of water is added at a rate of 200 kg of quicklime, but the water is raised from 18 degrees Celsius to 55 degrees Celsius, and in the carbonation step, the above-mentioned water It rises from 40 degrees Celsius to 60 degrees Celsius. During the hydration process, an exothermic reaction occurs and the temperature rises.

In the case of manufacturing a prototype of spindle-shaped synthetic calcium carbonate, synthetic calcium carbonate is produced by blowing CO ₂ gas into calcium hydroxide suspension and reacting. In order to control the shape and particle size, the concentration, temperature, stirring speed, carbon dioxide gas concentration and flow The reaction conditions are tested while watching PH and electrical conductivity changes by controlling the etc. to manufacture synthetic calcium carbonate of the optimal desired shape and size.

In addition, in the case of making cubic-type precipitated calcium carbonate, unlike the case of making spindle-type precipitated calcium carbonate, the temperature must be controlled. In the hydration step described above, 1,000 liters of water is added at a rate of 100 kg of quicklime, but the water rises from 18 degrees Celsius to 36 degrees Celsius, but does not rise above 30 degrees Celsius by using groundwater heat exchange through a double jacket controlled so as not to In addition, in the carbonation step, the water is raised from 25 degrees Celsius to 43 degrees Celsius, but is controlled so as not to rise above 35 degrees Celsius by using groundwater heat exchange through a double jacket.

3 is a SEM photograph of spindle-shaped precipitated calcium carbonate prepared according to the method for preparing precipitated calcium carbonate according to the present invention, and FIG. It is a picture.

Domestic specifications for spindle-shaped precipitated calcium carbonate are d50 of 2.5 μm and whiteness of 93. The present applicant developed a product with a whiteness of 94 or more by increasing the whiteness while meeting the conditions of particle size d50 of 2.5 μm and spindle shape of particle. In addition, the import specifications of cubic-type precipitated calcium carbonate are cubic-type precipitated calcium carbonate with d50 of 0.05 to 3.0 μm and whiteness of 91 to 98.

Using the above-described technology, the domestic ecosystem currently imports and operates most of the high-color limestone and high-color quicklime. product can be manufactured.

As described above, although the present invention has been described by the limited embodiments and drawings, the present invention is not limited thereto, and the technical spirit of the present invention and the following by those skilled in the art to which the present invention belongs Of course, various modifications and variations are possible within the scope of equivalents of the claims to be set forth.

Claims (7)

Preparing calcium carbonate ore by using selective mining and selective beneficiation;
A calcination step of calcining the calcium carbonate ore at a low temperature to produce quicklime;
A hydration step of making a calcium hydroxide suspension by reacting the quicklime with water; and
A carbonation step of making calcium carbonate by blowing CO2 gas into the calcium hydroxide suspension to react,
The hydration step is
When the quicklime is reacted with water, calcium hydroxide particles are fined through hydration delay by adding an additive made of black sugar, and the powder aggregated by the additive and the finely divided calcium hydroxide particles are classified a first whiteness enhancing step; and
A second whiteness improvement step of refining the calcium hydroxide suspension to which the additive is added using a screen and a magnet,
The carbonation step includes a third whiteness enhancement step of performing flotation on the prepared calcium carbonate.
Method for producing precipitated calcium carbonate.
delete delete delete delete According to claim 1,
After the carbonation step, adding a flotation agent; further comprising,
The flotation agent consists of a first flotation agent and a second flotation agent,
The first floating agent,
greater than 35% and less than 40% by weight of 2-ethylhexanol;
greater than or equal to 35% but less than 40% by weight of distillates (petroleum), distillates (petroleum), hydrotreated light; and
25% by weight or more and less than 30% by weight of N-oleyl 1,3-diaminopropane;
The second floating agent,
25% to 50% alcohol by weight;
25% to 50% by weight of distillates (petroleum), hydrotreated light; and
25% to 50% by weight of fatty amine derivative; characterized in that consisting of,
Method for producing precipitated calcium carbonate.
According to claim 1,
In the case of making spindle-shaped precipitated calcium carbonate,
In the hydration step, 200 kg of quicklime is added to 1,000 liters of water, and the water is raised from 18 degrees Celsius to 55 degrees Celsius,
In the carbonation step, the water is raised from 40 degrees Celsius to 60 degrees Celsius,
In the case of making cubic precipitated calcium carbonate,
In the hydration step, 1,000 liters of water is added at a rate of 100 kg of quicklime, but if there is no groundwater heat exchange through a double jacket, the water rises from 18 degrees Celsius to 36 degrees Celsius, using groundwater heat exchange through a double jacket The water is restricted so that it does not rise above 30 degrees Celsius,
In the carbonation step, if there is no groundwater heat exchange through the double jacket, the water is raised from 25 degrees Celsius to 43 degrees Celsius. ,
Method for producing precipitated calcium carbonate.