KR20230094498A - Manufacturing method of crushed limestone for mineral paper with improved whiteness - Google Patents

Abstract

The present invention relates to a manufacturing method of crushed limestone for mineral paper with improved whiteness, and more specifically, provides a manufacturing method of crushed limestone for mineral paper with improved whiteness which comprises: a crushing step which crushes limestone jaw-crushed and cone-crushed by a wet process; an adding crushing step which simultaneously inserts a calcium hydroxide aqueous solution and a titanium tetrachloride aqueous solution into a limestone slurry crushed in the crushing step and then additionally crushes the same; a drying step which dries the limestone slurry crushed in the adding crushing step; and a disintegrating step which disintegrates a limestone cake generated in the drying step. Accordingly, the manufacturing method can increase process efficiency and uniformly coat titanium dioxide compared with existing technologies. In addition, the present invention provides a manufacturing method of crushed limestone for mineral paper with improved whiteness which comprises: a crushing step which crushes limestone jaw-crushed and cone-crushed by a wet process; an agitating step which simultaneously inserts a calcium hydroxide aqueous solution and a titanium tetrachloride aqueous solution into a limestone slurry crushed in the crushing step and then agitates the same; and a disintegrating step which disintegrates a limestone cake generated in the drying step.

Description

Manufacturing method of crushed limestone for mineral paper with improved whiteness {Manufacturing method of crushed limestone for mineral paper with improved whiteness}

The present invention relates to a method of increasing the whiteness of pulverized limestone used in the manufacture of mineral paper, and more particularly, by uniformly coating titanium dioxide on the surface of pulverized limestone powder used in the manufacture of mineral paper to increase the whiteness. It relates to a method for increasing the whiteness of pulverized limestone to be increased.

Mineral paper refers to recycled paper made by recycling stones discarded from quarries or mines, not trees.

It is also called stone paper or stone paper because it uses 'mineral', which is the powder of stone.

Paper made by mixing lime powder and ‘polyethylene’, a water-repellent material, in an appropriate ratio, is eco-friendly because it does not use trees, so replacing 1 ton of ordinary paper with mineral paper has the effect of saving 20 trees and 95 liters of water.

Mineral paper made by adding 80% or more of calcium carbonate was first developed in Taiwan, and based on this technology, US Patent Publication No. 2012-0211189 (August 23, 2012) "METHOD FOR MANUFACTURING RECYCLABLE MINERAL PAPER" Manufacturing process)" discloses mineral paper containing 60 to 85% of natural minerals and a manufacturing method thereof.

According to the above patent, limestone powder obtained by pulverizing natural limestone with calcium carbonate is used, but the mineral paper prepared in this way has a problem in that whiteness is low.

That is, when mineral paper is produced using 80% or more of natural limestone pulverized material according to a conventional patented method, the whiteness is low, so that it cannot be used in fields where whiteness is important.

In particular, since natural limestone in Korea is gray-colored limestone, products with high whiteness cannot be made with this gray-colored limestone powder. there will be

As a method for improving whiteness, Japanese Patent Registration No. 05702590 (2015.02.27) "COMPOSITE PARTICLE, COMPOSITE PARTICLE-INTERNALLY ADDED PAPER, AND COATED PAPER (composite particle, composite particle internal addition and coated paper)" contains titanium dioxide (TiO ₂ ) is added and carbonated to produce a CaCO ₃ -TiO ₂ composite powder.

However, when titanium dioxide (TiO ₂ ) already made of oxide is added to calcium carbonate, there is a problem in that a separate titanium dioxide (TiO ₂ ) manufacturing process and cost occur. In addition, titanium dioxide should be coated to include calcium carbonate particles, but there is also a problem in that it does not sufficiently contribute to improving the whiteness in a state where it is buried or mixed on the surface of the calcium carbonate particles.

US Patent Publication No. 2012-0211189 (2012.08.23) Japanese Patent Registration No. 05702590 (2015.02.27)

Therefore, in the present invention, instead of adding titanium dioxide (TiO ₂ ), which is known to have excellent whiteness and hiding power, to reduce coating cost and promote process rationalization by suggesting a new method of titanium dioxide (TiO ₂ ) coating, the intermediate raw material Titanium tetrachloride (TiCl ₄ ), a substance, is added to the limestone crushing process to increase the process efficiency and increase the efficiency of the crushed limestone powder by using a one-step method in which titanium dioxide (TiO ₂ ) is automatically coated on the surface of the limestone at the same time as the limestone is crushed. It is intended to provide a manufacturing method of pulverized limestone for mineral paper having improved whiteness that enables coating of a thin titanium film. In addition, it is intended to provide a method for producing pulverized limestone for mineral paper with improved whiteness by further increasing coating efficiency by charging an aqueous solution of calcium hydroxide and an aqueous solution of titanium tetrachloride to the slurry of pulverized limestone.

In order to achieve the above object of the present invention, in the present invention, the crushing step of crushing the coarsely crushed and heavy crushed limestone in a wet process; An additional crushing step of simultaneously charging an aqueous solution of calcium hydroxide and an aqueous solution of titanium tetrachloride, which is an intermediate raw material, to the limestone slurry pulverized in the crushing step, and then additionally crushing the slurry; A drying step of drying the limestone slurry pulverized in the additional grinding step; and a pulverizing step of pulverizing the limestone cake produced in the drying step.

According to a preferred feature of the present invention, the limestone slurry pulverized in the crushing step may have a particle size of 325 to 375 mesh.

According to a preferred feature of the present invention, the calcium hydroxide aqueous solution is obtained by pulverizing steelmaking slag to 45 μm or less, injecting water to adjust the pH to 12 or more, and then separating the undissolved powder and the effluent by filtration to obtain a calcium ion eluate having a pH of 12 or more. It can be characterized in that it is made by a method comprising an extraction step.

According to a more preferred feature of the present invention, the steelmaking slag may be selected from the group consisting of converter slag, dephosphorization slag, desiliconization slag, stainless slag, electric furnace oxidizer slag and electric furnace reducer slag.

According to a preferred feature of the present invention, the calcium hydroxide aqueous solution may be characterized in that it is an aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved.

According to a preferred feature of the present invention, the particle size of the limestone slurry pulverized in the additional grinding step may have a D80 value of 1 to 3 μm.

According to a preferred feature of the present invention, the pulverized limestone for mineral paper may have a whiteness of 98% or more.

In order to achieve the above object of the present invention, in the present invention, the crushing step of crushing the coarsely crushed and heavy crushed limestone in a wet process; A stirring step of simultaneously charging an aqueous solution of calcium hydroxide and an aqueous solution of titanium tetrachloride to the limestone slurry pulverized in the pulverization step and then stirring; A drying step of drying the limestone slurry stirred in the stirring step; and a pulverizing step of pulverizing the limestone cake produced in the drying step.

According to a preferred feature of the present invention, the particle size of the limestone slurry pulverized in the crushing step may be characterized in that the D80 value is 1 to 3 μm.

According to a preferred feature of the present invention, the calcium hydroxide aqueous solution is obtained by pulverizing steelmaking slag to 45 μm or less, injecting water to adjust the pH to 12 or more, and then separating the undissolved powder and the effluent by filtration to obtain a calcium ion eluate having a pH of 12 or more. It can be characterized in that it is made by a method comprising an extraction step.

According to a more preferred feature of the present invention, the steelmaking slag may be selected from the group consisting of converter slag, dephosphorization slag, desiliconization slag, stainless slag, electric furnace oxidizer slag and electric furnace reducer slag.

According to a preferred feature of the present invention, the calcium hydroxide aqueous solution may be characterized in that it is an aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved.

According to a preferred feature of the present invention, the pulverized limestone for mineral paper may have a whiteness of 98% or more.

The manufacturing method of the present invention increases process efficiency compared to the prior art, and can uniformly coat titanium dioxide, thereby providing limestone pulverized material for mineral paper with improved whiteness.

1 shows a manufacturing process flow chart according to an embodiment of the present invention.
2 shows another manufacturing process flow chart according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Accordingly, the embodiments of the present invention can be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below.

Throughout the specification of the present invention, when a part "includes" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

Throughout the specification of the present invention, when a step is said to be located “on” or “before” another step, this means that a step is in a direct time-series relationship with another step, as well as the mixing step after each step. As such, the order of the two steps may include the same rights as in the case of an indirect time-series relationship in which the time-series order may change.

The terms "about", "substantially", etc., of degrees used throughout the specification of the present invention are used at or approximating that value when manufacturing and material tolerances inherent in the stated meaning are given, and the present invention Accurate or absolute figures are used to prevent unfair use by unscrupulous infringers of the disclosed disclosures mentioned for the sake of understanding. The term "step of (doing)" or "step of" used throughout the present specification does not mean "step for".

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention. The terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to explain their invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

In order to achieve the above object of the present invention, a crushing step (S101) of crushing coarse and medium crushed limestone in a wet process, adding an aqueous solution of calcium hydroxide and an aqueous solution of titanium tetrachloride to the limestone slurry crushed in the crushing step at the same time, followed by additional grinding An additional crushing step (S103) comprising a drying step (S105) of drying the limestone slurry crushed in the additional crushing step and a crushing step (S107) of crushing the limestone cake generated in the drying step. Improved whiteness A method for producing a pulverized limestone for mineral paper having is provided.

Since the mineral paper is intended to be used as printing paper or writing paper, the inorganic mineral (calcium carbonate), which is the main raw material, must be pure white. It was possible only by using the one with high purity and whiteness through a process.

As above, calcium carbonate with high whiteness and purity is obtained by selecting raw stones with a whiteness of 95% or more, pulverizing them to tens of micrometers or less through 3-4 grinding processes, and then reprocessing to obtain calcium carbonate with a purity of 98% or more. It had to be modified, and this process is a very expensive process, which causes an increase in manufacturing cost.

Limestone, which is a raw material required for the manufacture of the mineral paper, is composed of calcium carbonate, and can be classified into organic sedimentary rocks and chemical sedimentary rocks according to its production source. Most of the rock is calcite, which reacts with hydrochloric acid to release carbon dioxide, and organic limestone is made from the carcasses of organisms that make their shells out of calcium carbonate. Representative organisms include corals, calcareous algae, and calcareous plankton. Therefore, many fossils are often found in organic limestone, and limestone is formed by precipitation in an environment where calcium carbonate is supersaturated. They are mostly gray, but appear in any color from white to black. Because it is easy to carve, it is often used as a building stone, and it is also used to make walls or bases for supporting pillars of buildings where polish is not very important.

In addition, it is used to purify waste gas and wastewater, and is used to make lime or smelt iron ore.

In the case of Korea, about 20.6 billion tons are buried (3000 years), so it is mined and used a lot to make cement.

As a method to increase the whiteness, there is a method of coating titanium dioxide on limestone.

Titanium dioxide is also called titanium dioxide or titanium dioxide, and its chemical formula is TiO ₂ . It is a molecule in which one atom of titanium, a transition metal, and two atoms of oxygen are combined. The molecular weight is 79.866g/mol. It is a tasteless and odorless white powder. When titanium is exposed to air, it readily reacts with oxygen to form a titanium dioxide film.

Until now, the titanium dioxide (TiO ₂ ) has been known to be a very stable material that is harmless to the environment and human body because it does not react biologically, but according to recent studies, it is said that there is a possibility of causing cancer in the human body.

The amount of titanium dioxide (TiO ₂ ) currently industrially manufactured is about 3 million tons per year worldwide. Produced titanium dioxide (TiO ₂ ) is used for several purposes. Among them, the amount used as a white paint accounts for about 90% of the total amount of titanium dioxide (TiO ₂ ) used. Methods for industrially producing titanium dioxide (TiO ₂ ) are largely divided into two methods: a sulfuric acid method and a chlorine method.

In the sulfuric acid method, anatase-type titanium dioxide (TiO ₂ ) microparticles, which are precipitates obtained by thermally hydrolyzing an aqueous solution of titanyl sulfate (TiOSO ₄ ), are calcined at 800 ~ 1000 ° C to grow them, and then titanium dioxide (TiO ₂ ) of a desired size is formed. how to get Desired crystals such as anatase-type and rutile-type can be produced by controlling the addition of seeds in the firing process.

The chlorine method is a method of forming TiO ₂ particles in a high-temperature gas phase by reacting heated steam of titanium tetrachloride (TiCl ₄ ) with heated oxygen. Unlike the sulfuric acid method, only the rutile type is produced.

It is preferable to utilize a chlorine method capable of reacting without other additives in the production method of the present invention.

Other manufacturing methods include a manufacturing method such as a CVD method (Chemical Vapor Deposition), a sol-gel method, and anodization as a method for manufacturing a titanium dioxide (TiO ₂ ) thin film.

The present invention has the advantage of reducing coating costs and promoting process rationalization by presenting a new method of titanium dioxide (TiO ₂ ) coating.

That is, instead of adding titanium dioxide (TiO ₂ ), titanium tetrachloride (TiCl ₄ ), a raw material for the chlorination reaction, is added to the limestone crushing process, so that titanium dioxide (TiO ₂ ) is automatically coated on the surface of the limestone at the same time as the crushing of the limestone. A one-step method was used to reduce process costs and a method in which titanium dioxide (TiO ₂ ) was uniformly coated on the surface of calcium carbonate was used.

In the conventional mineral paper manufacturing method, the titanium dioxide (TiO ₂ ) powder itself is added, so that the calcium carbonate surface is not completely uniformly coated, and the calcium carbonate surface is unevenly embedded with titanium dioxide (TiO ₂ ). In the simultaneous coating of only the first step of the invention, since the titanium dioxide (TiO ₂ ) film is uniformly coated on the surface with calcium carbonate as the nucleus, this method is excellent in terms of uniformity of the coating film.

In the grinding step (S101), limestone slurry is formed by wet grinding into fine powder through a ball mill or pot mill grinding equipment. In the case of grinding while reducing product loss, wet grinding is preferably used for raw materials that generate a lot of dust, raw materials that may ignite, etc. In the case of limestone, a method of making a slurry by wet grinding is useful.

The additional grinding step (S103) is an aqueous solution of calcium hydroxide and titanium tetrachloride It is a complex process step in which the limestone slurry is additionally pulverized after charging the aqueous solution. It is a process of pulverizing the limestone particles more finely so that the grain size is in the micrometer unit, and at the same time, titanium dioxide (TiO ₂ ) is produced and coated. After finishing the ball grinding in the following contents, calcium hydroxide aqueous solution and titanium tetrachloride Compared to other embodiments of the present invention in which an aqueous solution is added and reacted while stirring, there is a problem such as separation of the coating portion, but the advantage of simplifying the process is great.

After the additional grinding step (S103), a drying step (S105) of sufficiently drying the product at a temperature of at least 100 ° C. to remove moisture to obtain a hard cake form.

After going through a crushing step (S107) of dissolving the cake shape by applying a certain physical force to the cake shape, a final product of pulverized limestone for mineral paper having improved whiteness is completed.

The limestone slurry pulverized in the crushing step (S101) preferably has a particle size of 325 to 375 mesh.

The reason for pulverizing into powder of 325 to 375 mesh is to facilitate the chemical reaction in which the mixture is agglomerated. At a particle size of 325 mesh or less, a phenomenon in which lumps do not agglomerate occurs, and a particle size exceeding 375 mesh In the particle weight is light, there is a problem of scattering in the air.

Preferably, the calcium hydroxide aqueous solution includes an extraction step of obtaining a calcium ion eluate having a pH of 12 or more by pulverizing the steelmaking slag to 45 μm or less, adjusting the pH to 12 or more by injecting water, and then separating the undissolved powder and the eluate by filtration. It is characterized in that it is made in a way to.

When titanium tetrachloride (TiCl ₄ ) reacts with a basic solution, titanium dioxide (TiO ₂ ) is produced. If a basic solution other than calcium hydroxide (Ca(OH) ₂ ) is used, the metal cation of the added basic solution eventually becomes an impurity Impurity ions in a basic solution that will not become impurities, that is, calcium hydroxide (Ca(OH) ₂ ) may contaminate the coated titanium dioxide (TiO ₂ ) and act as a factor in reducing whiteness. Therefore, it is preferable to use high-purity calcium hydroxide (Ca(OH) ₂ ) used in the manufacturing method for obtaining 99.9% pure calcium carbonate in the present invention.

In order to manufacture the high-purity calcium hydroxide (Ca(OH) ₂ ), as a calcium source, steelworks byproduct steelmaking slag in which calcium exists as calcium oxide is used. When the steelmaking slag is pulverized and reacted with water, a strong alkaline calcium eluate containing few impurities and free calcium ions dissolved therein is obtained.

At this time, the steelmaking slag is pulverized to a particle size of 45 μm or less so that calcium components can be effectively eluted. In the case of 45 μm or less, the calcium component is eluted more quickly and effectively.

Furthermore, when carbon dioxide gas or exhaust gas containing carbon dioxide gas is blown into the strong alkaline calcium ion elution solution while being well dispersed through an aeration pipe and reacted, calcium carbonate, which is a white precipitate, is produced and the reaction solution turns milky. The obtained white precipitate is separated to obtain calcium carbonate (CaCO ₃ ).

However, at this time, carbon dioxide or carbon dioxide-containing exhaust gas is continuously injected into the solution that has turned milky white, and the calcium carbonate produced as the pH is lowered to less than 7 is re-dissolved into calcium bicarbonate, and the calcium carbonate (CaCO ₃ ) precipitate disappears, resulting in a clear solution. do. Therefore, it is necessary to react the calcium ion eluate with carbon dioxide or carbon dioxide-containing exhaust gas in a pH range in which calcium bicarbonate is not converted, that is, in the pH range where calcium carbonate (CaCO ₃ ) exists, and the precipitate is separated. That is, during the reaction of the calcium ion eluting solution with carbon dioxide or carbon dioxide-containing exhaust gas, the pH should be maintained at 7 or more, preferably 8 or more.

By producing a strong alkaline calcium ion eluate using the steelmaking slag, carbon dioxide gas generated during the production of slaked lime oil from conventional limestone is not generated, and by preparing calcium carbonate using the calcium ion eluate, high purity of 99.9% or more without contamination of impurities. of calcium carbonate (CaCO ₃ ) can be obtained.

The above description relates to a method for producing high-purity calcium carbonate as the contents of Korean Patent No. 10-0922563 of the present inventor. In addition, it is possible to obtain a high-purity calcium hydroxide (Ca(OH) ₂ ) aqueous solution in the intermediate step. Due to its high purity, it is possible to obtain limestone pulverized material for mineral paper with a higher degree of whiteness.

More preferably, the steelmaking slag is characterized in that it is selected from the group consisting of converter slag, dephosphorization slag, desiliconization slag, stainless slag, electric furnace oxidizer slag and electric furnace reducer slag.

Further, any steelmaking slag containing 20 to 52% by weight of calcium oxide may be used.

Preferably, the calcium hydroxide aqueous solution is characterized by being an aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved.

Calcium hydroxide prepared by including an extraction step of pulverizing the above-described steelmaking slag to 45㎛ or less, injecting water to adjust the pH to 12 or more, and then separating the undissolved content and the eluate by filtration to obtain a calcium ion eluate of pH 12 or more ( The Ca(OH) ₂ ) solution is an aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved.

Limestone for mineral paper made through the manufacturing method of the present invention by using the calcium hydroxide (Ca(OH) ₂ ) aqueous solution having a purity of 99.9% or more prepared by the above manufacturing method to prevent the influence of impurities that hinder whiteness improvement in advance The pulverized product may exhibit a further improved whiteness.

Preferably, the particle size of the limestone slurry pulverized in the additional grinding step is characterized in that the D80 value is 1 to 3 μm.

There are many different ways to calculate the diameter of a particle shape. The principle of the equipment for measuring the particle size is also different for each equipment. What we need to pay attention to is what calculation method (Mn, Mv, Ma) will be used when measuring the particle size, respectively. For example, when a laser particle size analyzer is used, laser is irradiated and the particle size is inferred from the correlation between diffraction and particle size. use the rescue method.

To say d50, d10, and d90, which are the easiest to understand, simply indicate the particle size corresponding to xx% of the number following d. D50 is said to be a medium particle size.

For example, for a powder sample with D50 = 5 μm, it means that there are 50% particles larger than 5 μm and 50% particles smaller than 5 μm.

In order to carry out the present invention, the calcium hydroxide (Ca(OH) ₂ ) aqueous solution and titanium tetrachloride (TiCl ₄ ) aqueous solution having a purity of 99.9% or more are charged to the pulverized limestone slurry, and the particle size of the limestone is 1 to 3 μm based on D80 It is desirable to additionally grind it until it becomes.

In this way, the titanium dioxide (TiO ₂ ) production reaction and stirring reaction proceed simultaneously with grinding, so that efficiency and uniform coating can be achieved by performing several steps in one process.

Preferably, the pulverized limestone for mineral paper has a whiteness of 98% or more.

The thickness of the titanium dioxide (TiO ₂ ) microparticles coated on the surface is preferably 0.1 to 100 nm. It satisfies the effect of maximizing the whiteness within the above range, and is particularly preferable when the particle diameter is 0.1 to 10 nm. When the thickness of the fine particles is less than 0.1 nm, the color development is remarkably reduced, which is not preferable, and when the thickness exceeds 100 nm, the coated surface becomes rough due to the excessive size of the particle diameter, which is not preferable.

The whiteness will be described in the following examples.

Another method for achieving the object of the present invention described above is a crushing step (S101) of crushing coarse and heavy crushed limestone in a wet process, adding an aqueous solution of calcium hydroxide and an aqueous solution of titanium tetrachloride to the limestone slurry crushed in the crushing step An agitation step of stirring after charging (S104), a drying step of the limestone slurry stirred in the stirring step (S105), and a crushing step of crushing the limestone cake generated in the drying step (S107). Provided is a method for producing pulverized limestone for mineral paper having whiteness.

Titanium tetrachloride (TiCl ₄ ) may be added and reacted during pulverization, but after completion of the pulverization process of the limestone, an aqueous solution of calcium hydroxide and titanium tetrachloride (TiCl ₄ ) A manufacturing method in which the aqueous solution is simultaneously charged and then stirred is also possible. The latter is superior in terms of efficacy due to less detachment of the coating.

There is no significant difference in the whiteness of the pulverized limestone produced in the above two manufacturing methods, but during the pulverization step, an aqueous solution of calcium hydroxide and titanium tetrachloride (TiCl ₄ ) Compared to charging the aqueous solution at the same time as charging the limestone slurry after the crushing step, the effect of simplifying the process can be obtained.

Preferably, the particle size of the limestone slurry pulverized in the crushing step may have a D80 value of 1 to 3 μm.

As described above, a uniform titanium dioxide (TiO ₂ ) coating can be realized in the corresponding particle size range.

Preferably, the calcium hydroxide aqueous solution includes an extraction step of obtaining a calcium ion eluate having a pH of 12 or more by pulverizing the steelmaking slag to 45 μm or less, adjusting the pH to 12 or more by injecting water, and then separating the undissolved powder and the eluate by filtration. It is characterized in that it is made in a way to.

As described above, by producing a strong alkaline calcium ion eluate using the steelmaking slag, carbon dioxide gas generated during the production of slaked lime oil from conventional limestone is not generated, and calcium carbonate (CaCO ₃ ) is produced using the calcium ion eluate to produce impurities. High purity calcium carbonate (CaCO ₃ ) of 99.9% or more without mixing of can be obtained.

In addition, high-purity calcium hydroxide (Ca(OH) ₂ ) can also be obtained during the process of producing the high-purity calcium carbonate (CaCO ₃ ).

When prepared using such high-purity calcium hydroxide (Ca(OH) ₂ ), it is possible to have more improved whiteness.

Preferably, the calcium hydroxide aqueous solution is characterized by being an aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved.

As described above, in order for the pulverized limestone for mineral paper produced by the manufacturing method of the present invention to exhibit improved whiteness compared to the conventional manufacturing method, an aqueous solution in which calcium hydroxide having a purity of 99.9% or more prepared by the manufacturing method is dissolved is used. It is more preferable to

Preferably, the pulverized limestone for mineral paper may have a whiteness of 98% or more.

As described above, the thickness of the titanium dioxide (TiO ₂ ) microparticles coated on the surface is preferably 0.1 to 100 nm. It satisfies the effect of maximizing the whiteness within the above range, and is particularly preferable when the particle diameter is 0.1 to 10 nm. When the thickness of the fine particles is less than 0.1 nm, the color development is remarkably reduced, which is not preferable, and when the thickness exceeds 10 nm, the coating force is reduced due to the excessive size of the particle diameter.

At this time, the analysis of the whiteness was performed through the ISO 2470 method, which is a whiteness measurement method.

Hereinafter, the present invention will be described in more detail with examples of the present invention.

<Comparative Example 1>

Crude and medium-crushed limestone was loaded into an experimental pot mill, pulverized until D80 was 3 μm or less, and the limestone slurry pulverized to a maximum of 3 μm or less was dried at 200 ° C. for 3 hours, and then pulverized.

<Example 1>

Crude and medium-crushed limestone was loaded into an experimental pot mill and pulverized to a size of 325 mesh or less. High-purity calcium hydroxide (Ca(OH) ₂ ) aqueous solution (calcium hydroxide solution in which calcium hydroxide having a purity of 99.9% or more is dissolved) and titanium tetrachloride (TiCl ₄ ) aqueous solution prepared by the method of Korean Patent No. 10-0922563 of the present inventor in pulverized limestone slurry was charged and the particle size of the limestone was pulverized until the D80 value was 3 μm or less.

The limestone slurry crushed to a maximum of 3 μm or less was dried at 200 ° C. for 3 hours while stirring, and then pulverized. Fine particles of titanium dioxide (TiO ₂ ) were coated on the surface of the crushed limestone powder.

<Example 2>

Crude and medium-crushed limestone was loaded into an experimental pot mill and pulverized until the D80 value was 3 μm or less.

While stirring the limestone slurry crushed to a maximum of 3 μm or less, the high-purity calcium hydroxide (Ca(OH) ₂ ) aqueous solution (calcium hydroxide aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved) and titanium tetrachloride (TiCl ₄ ) aqueous solution are simultaneously charged while sufficiently stirring did

After the stirring was completed, the mixture was slowly dried at 200° C. for 3 hours while stirring. The dried limestone cake was pulverized.

Fine particles of titanium dioxide (TiO ₂ ) were coated on the surface of the crushed limestone powder.

Table 1 below shows the whiteness measurement results of Comparative Examples and Examples. Comparative Example 1 Example 1 Example 2 whiteness 87% 98% 98%

As can be seen in Table 1, it was confirmed that titanium dioxide (TiO ₂ ) coated Examples 1 and 2 had improved whiteness compared to conventional limestone.

As above, the scope of the present invention is indicated by the claims to be described later rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof are included in the scope of the present invention. should be interpreted as being

S101: grinding step S103: additional grinding step
S104: stirring step S105: drying step
S107: disintegration step

Claims (13)

A crushing step of crushing the crushed and heavy crushed limestone in a wet process;
Calcium hydroxide aqueous solution and titanium tetrachloride in the crushed limestone slurry in the crushing step Additional pulverization step of additionally pulverizing after simultaneously charging the aqueous solution;
A drying step of drying the limestone slurry pulverized in the additional grinding step; and
A method for producing pulverized limestone for mineral paper having improved whiteness, characterized in that it comprises a; pulverizing step of pulverizing the limestone cake produced in the drying step. According to claim 1,
The method of producing pulverized limestone for mineral paper with improved whiteness, characterized in that the limestone slurry pulverized in the crushing step has a particle size of 325 to 375 mesh. According to claim 1,
The calcium hydroxide aqueous solution is an extraction step in which the steelmaking slag is pulverized to a size of 45 μm or less, water is injected to adjust the pH to 12 or more, and then the undissolved powder and the effluent are separated by filtration to obtain a calcium ion eluate having a pH of 12 or more.
Method for producing pulverized limestone for mineral paper having improved whiteness, characterized in that it is made by a method comprising a. According to claim 3,
The steelmaking slag is selected from the group consisting of converter slag, dephosphorization slag, desiliconization slag, stainless slag, electric furnace oxidizer slag and electric furnace reducer slag. According to claim 1,
The calcium hydroxide aqueous solution is a method for producing pulverized limestone for mineral paper with improved whiteness, characterized in that the aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved. According to claim 1,
The method of producing pulverized limestone for mineral paper with improved whiteness, characterized in that the particle size of the limestone slurry pulverized in the additional grinding step has a D80 value of 1 to 3 μm. According to claim 1,
The method of producing a pulverized limestone for mineral paper having improved whiteness, characterized in that the whiteness of the pulverized limestone for mineral paper is 98% or more. A crushing step of crushing the crushed and heavy crushed limestone in a wet process;
A stirring step of simultaneously charging an aqueous solution of calcium hydroxide and an aqueous solution of titanium tetrachloride to the limestone slurry pulverized in the pulverization step and then stirring;
A drying step of drying the limestone slurry stirred in the stirring step; and
A method for producing pulverized limestone for mineral paper having improved whiteness, characterized in that it comprises a; pulverizing step of pulverizing the limestone cake produced in the drying step. According to claim 8,
Method for producing pulverized limestone for mineral paper with improved whiteness, characterized in that the particle size of the limestone slurry pulverized in the grinding step has a D80 value of 1 to 3 μm. According to claim 8,
The calcium hydroxide aqueous solution is an extraction step in which the steelmaking slag is pulverized to a size of 45 μm or less, water is injected to adjust the pH to 12 or more, and then the undissolved powder and the effluent are separated by filtration to obtain a calcium ion eluate having a pH of 12 or more.
Method for producing pulverized limestone for mineral paper having improved whiteness, characterized in that it is made by a method comprising a. According to claim 10,
The steelmaking slag is selected from the group consisting of converter slag, dephosphorization slag, desiliconization slag, stainless slag, electric furnace oxidizer slag and electric furnace reducer slag. According to claim 1,
The calcium hydroxide aqueous solution is a method for producing pulverized limestone for mineral paper with improved whiteness, characterized in that the aqueous solution in which calcium hydroxide having a purity of 99.9% or more is dissolved. According to claim 8,
The method of producing a pulverized limestone for mineral paper having improved whiteness, characterized in that the whiteness of the pulverized limestone for mineral paper is 98% or more.

Images