KR101889355B1 - Manufacturing method of porous ceramics from red mud and tailing - Google Patents

Abstract

One embodiment of the present invention provides a method for manufacturing a porous ceramic, comprising the steps of: (a) manufacturing a mixed solution comprising red mud, tailing, ceramic fibers, a water-soluble polymer, and a surfactant; (b) adding an organic solvent to the mixed solution and freezing the same; (c) defrosting the frozen mixture and performing a first heat treatment; and (d) performing a second heat treatment of the first heat-treated material and sintering the same. According to the present invention, a porous ceramic having excellent characteristics can be manufactured by the method.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing porous ceramics,

More particularly, the present invention relates to a method for producing a porous ceramic by freezing and heat-treating a mixture comprising red mud, mineral wax, ceramic fibers, water-soluble polymer and surfactant .

Considering the environmental aspect, many suggestions have been made to utilize red mud, which is a by - product of aluminum smelting, as a ceramic material such as refractory bricks. In order to improve the thermal insulation performance of refractory bricks, it is known to mix red mud with sawdust or carbon to form a certain shape, and then to form pores by combustion and vaporization of sawdust and carbon through high temperature heat treatment and sintering.

As described above, it is difficult to obtain a porosity of 70% or more by adding carbon or sawdust to form pores by combustion thereof, and since the pore size is also relatively large, it is difficult to expect application as a filter other than a heat insulating material There are disadvantages.

A related art is disclosed in Korean Patent Registration No. 10-0652201 entitled "Method for manufacturing brick using red mud, " and" Method for manufacturing porous lightweight building material using red mud, "disclosed in Korean Patent Publication No. 10-0240943 have.

Korean Patent Registration No. 10-0652201 (published on November 23, 2006) Korean Patent Registration No. 10-0240943 (issued October 30, 1999)

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art described above, and it is an object of the present invention to provide a method and apparatus for recovering aluminum from smelting by- And to provide a porous ceramic produced by the method.

In order to accomplish the above object, one aspect of the present invention is a method for producing a mixed solution comprising: (a) preparing a mixed solution comprising red mud, mineral wax, ceramic fibers, a water-soluble polymer and a surfactant; (b) adding an organic solvent to the mixed solution and freezing it; (c) thawing the frozen material and subjecting it to a first heat treatment; And (d) subjecting the first heat-treated material to a second heat treatment and sintering the porous ceramic material.

In order to achieve the above object, another aspect of the present invention provides a composition for preparing porous ceramic by freezing and heat treatment, which comprises red mud, mineral wax, ceramic fiber, water-soluble polymer, surfactant and organic solvent.

In order to achieve the above object, another aspect of the present invention provides a porous ceramic produced by the above method, wherein the porous ceramic has an apparent porosity of 72-80% and an average pore size of 146-166 탆 .

According to one aspect of the present invention, porous ceramics exhibiting properties that are observed through freezing, multistage heat treatment, and sintering can be manufactured using aluminum smelting by-products, mine waste, ceramic fibers, water-soluble polymers, surfactants, and organic solvents.

The porous ceramics produced according to an embodiment of the present invention may have an apparent porosity of 72-80%, an average pore size of 146-166 탆, and a thermal conductivity of 0.1-0.2 W / mK.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a flowchart showing an example of a method of manufacturing a porous ceramic according to an embodiment of the present invention.
FIG. 2 is a schematic view showing another example of a method of manufacturing a porous ceramic according to an embodiment of the present invention.
3 is a graph showing the apparent porosity of the porous ceramics performed in Experimental Example 1 of the present invention.
4 is a graph showing the thermal conductivity of the porous ceramics performed in Experimental Example 3 of the present invention.
5 is a photograph of a material mixed in Example 1 of the present invention and a photograph of a finally produced porous ceramic.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

It should be understood, however, that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. To fully inform the inventor of the category of invention. Further, the present invention is only defined by the scope of the claims.

Further, in the following description of the present invention, if it is determined that related arts or the like may obscure the gist of the present invention, detailed description thereof will be omitted.

One aspect of the present invention is

(a) preparing a mixed solution containing red mud, mineral wax, ceramic fiber, water-soluble polymer, and surfactant (S10);

(b) adding an organic solvent to the mixed solution and freezing (S20);

(c) defrosting the frozen material and performing a first heat treatment (S30); And

(d) subjecting the first heat-treated material to a second heat treatment and sintering (S40).

Hereinafter, a method of manufacturing a porous ceramic according to an embodiment of the present invention will be described step by step.

In the method for producing a porous ceramic according to an embodiment of the present invention, the step (a) (S10) comprises preparing a mixed solution in which red mud, mineral wax, ceramic fiber, water-soluble polymer and surfactant are mixed according to a predetermined weight ratio.

The red mud is a residue formed after aluminum is extracted from bauxite, which is a raw mineral of aluminum, and can be reddish brown because it contains iron oxide and silica. In general, red mud is used as building materials such as road construction, glass ceramics, pozzolan as a cement mixed material, etc. However, in one embodiment of the present invention, it was tried to utilize it as porous ceramics having refractory materials and filters.

The red mud in step (a)

Silica (SiO ₂₎ 11.9-15.3 wt%;

Alumina _{(Al 2 O 3) 24.4-29.1 wt} %;

30.6-35.9 wt% iron oxide (Fe ₂ O ₃ );

3.7-6.2 wt% of calcium oxide (CaO);

Sodium oxide (Na ₂ O) 7.9-10.8 wt%;

Titanium oxide (TiO ₂₎ 6.0-8.7 wt%; may include.

The tailings are the remaining residues after collecting the beneficial minerals of the mine and remaining residue, and collecting the concentrates as a mating partner of the concentrates. Most of the problems after mine abandonment are caused by the deposits of these minerals, and researches are needed to treat them. In one embodiment of the present invention, the present invention is applied to porous ceramics having refractory materials and filters.

The tailings of step (a) may be a gold mine which is a remnant generated during the development of a gold mine.

The tailings of step (a)

Silica (SiO ₂₎ 86.9-91.8 wt%;

And 5.0-8.2 wt% alumina (Al ₂ O ₃ )

0.1-2.1 wt% of iron oxide (Fe ₂ O ₃ );

Calcium oxide (CaO) 0.1-1.1 wt%;

Magnesium oxide (MgO) 0.1-1.2 wt%;

Potassium oxide (K ₂ O) 0.1-2.3 wt%;

Titanium oxide (TiO ₂₎ 0.1-1.2 wt%; And the like.

The ceramic fiber in the step (a) may include one selected from the group consisting of silica, alumina, aluminosilicate, aluminoborosilicate, mullite, glass fiber, and combinations thereof, Silimanite (Al ₂ SiO ₅ ) can be used.

The ceramic fibers of step (a) preferably have a length of 2 cm or less, and may be one of conditions for easily producing a target porous ceramic.

The water-soluble polymer in step (a) may be polyvinyl alcohol, and a water-soluble polymer having a boiling point in a second heat treatment range in the subsequent step may be used.

The water-soluble polymer of step (a) is preferably added in a concentration of 5-20 wt%.

When the water-soluble polymer in step (a) is polyvinyl alcohol, the number average molecular weight is preferably 100,000 to 200,000.

The surfactant of step (a) may be selected from the group consisting of alkyl, olefin, sodium, benzene, lignin, melamine, naphthalene, aminosulfonic acid, polycarboxylic acid and polyether surfactants It is preferable to use at least one anionic surfactant such as an aminosulfonic acid-based surfactant.

The mixed solution of the step (a) preferably contains the red mud and the tail mud at a weight ratio of 1: 0.25 to 0.67 (8: 2 to 6: 4). If the weight ratio is less than 1: 0.25, there is a possibility that the sintering time for obtaining the desired strength may increase. If the weight ratio is more than 1: 0.67, .

Preferably, the mixed solution of step (a) includes 6 to 10 parts by weight of ceramic fibers per 100 parts by weight of the mixture of the red mud and the tailings. The ceramic fibers are contained in the weight ratio range described above, and the effect of suppressing the formation of cracks in the sintered body during sintering through the support function can be expected.

It is preferable that 90 to 110 parts by weight of the water-soluble polymer solution is added to 100 parts by weight of the mixed solution of the red mud, the tailings and the ceramic fiber. The water-soluble polymer is included in the above-mentioned weight ratio range so that the aimed characteristic of the ceramic can be achieved through a subsequent step.

It is preferable that the surfactant of the step (a) is added in an amount of 3-6 vol% relative to the solution of the water-soluble polymer in the pore formation of the subsequent step.

In the porous ceramic manufacturing method according to an embodiment of the present invention, the organic solvent is added to the prepared mixed solution in the step (b) and the freezing is performed.

The organic solvent of step (b) preferably has a boiling point in the range of the first heat treatment temperature, and specifically, n-pentane may be used.

The step (b) may include reducing the pressure of the mixed solution to 0.05-0.2 atm before adding the organic solvent. By performing the depressurization in the above-mentioned pressure range, the internal bubbles can be removed, and the stirring efficiency can be improved.

The addition of the organic solvent in the step (b) by 90-110 vol% to the surfactant is preferable for the formation of pores through the subsequent step.

The freezing of step (b) is preferably performed at a temperature of -30 ° C to -10 ° C for 12-36 hours. After freezing at the above-mentioned temperature and time range, it is thawed to obtain a gel-like specimen. This has the advantage of facilitating machining and processing in subsequent processes.

In the porous ceramic manufacturing method according to an embodiment of the present invention, the frozen mixed solution is defrosted in step (c) (S30) and the first heat treatment is performed at a predetermined temperature.

The thawing of step (c) is preferably performed at room temperature.

The first heat treatment temperature in step (c) is preferably performed at 40-80 ° C for 12-36 hours, but may be shortened according to the size of the specimen and the heat treatment environment. If the first heat treatment temperature is less than 40 ° C, some organic solvent may remain and pore formation may be insufficient. If the first heat treatment temperature exceeds 80 ° C, the organic solvent may be vaporized to form pores Excessive energy waste may occur. The desired micropores can be effectively formed at the first heat treatment temperature and time range.

In the porous ceramic manufacturing method according to an embodiment of the present invention, the step (d) (S40) comprises subjecting the first heat-treated material to a second heat treatment and sintering at a predetermined temperature.

In the step (d), the water-soluble polymer is completely removed through the second heat treatment after drying the first heat-treated material.

The second heat treatment in the step (d) is preferably performed at a temperature of 300-600 ° C for 1-5 hours. If the second heat treatment temperature is less than 300 ° C., the water-soluble polymer may remain in the treated substance in step (c). If the second heat treatment temperature is higher than 600 ° C., excessive energy waste May occur. A second heat treatment is performed in the temperature and time ranges described above so that the subsequent sintering treatment can be effectively performed.

The sintering in step (d) is preferably performed at a temperature of 1200-1350 캜 for 30-120 minutes. The sintering is carried out in the above temperature and time range, and finally, a target porous ceramic can be produced.

In another aspect of the present invention,

There is provided a composition for producing a porous ceramic by freezing and heat treatment, which comprises red mud, wort, ceramic fiber, water-soluble polymer, surfactant and organic solvent.

Specific materials and mixing ratios of the above red mud, mineral wax, ceramic fiber, water-soluble polymer, surfactant and organic solvent may be as described in the above production method.

The freezing and heat treatment may be the same as the freezing, the first heat treatment, the second heat treatment and the sintering described in the above production method.

In another aspect of the present invention,

The porous ceramic produced by the above-described method has an apparent porosity of 72-80% and an average pore size of 146-166 탆.

The porous ceramics can be produced by the above-described production method, so that it can exhibit a relatively high porosity and a finer pore size compared to a ceramic in which sawdust or carbon is burned to form pores.

The porous ceramic can be used as a filter, and can exhibit excellent performance particularly when used as a sulfur oxide (SO _x ) filter.

The porous ceramics may have a thermal conductivity of 0.1-0.2 W / mK and may be used as insulation as well as a filter.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following examples and experimental examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

"Preparations and gold mining preparations"

The composition of gold dust and red mud to be used in the embodiment of the present invention was analyzed through WD-XRF of Shimadzu Corporation, and the results are shown in Table 1.

Classification Gold mine Redness SiO ₂ 87.9 12.9 Al ₂ O ₃ 6 25.4 Fe ₂ O ₃ 1.1 31.6 CaO 0.1 4.7 MgO 0.2 - Na ₂ O - 8.9 K ₂ O 1.3 - TiO ₂ 0.2 7 LOI 3.2 9.5 Sum 100 100

(Unit: wt%, LOI: ignition loss)

&Quot; Optimum Embodiment 1 " Porous ceramic production (red mud 80: mud 20)

(a) 240 g of a material mixed so as to have a mixing weight ratio of 8: 2 of red mud and tail mixed with the composition of Table 1 was prepared and 20 g of aluminosilicate fiber was finely torn and mixed in 260 mL of polyvinyl alcohol aqueous solution . To the mixed solution was added 12 mL of an anionic surfactant containing an alkyl-ether-sulfate as a main component.

(b) The mixed solution was reduced to 0.1 atm. 12 mL of n-pentane was added to the depressurized mixture, and the mixture was frozen for 24 hours in a freezer at -20 ° C.

(c) The frozen material was thawed at room temperature and heat-treated in an oven at 60 캜 for 24 hours.

(d) The heat-treated material was placed in a box furnace and heat-treated at a temperature of 500 ° C for 2 hours, then heated to 1250 ° C, sintered for 30 minutes, and cooled to prepare a porous ceramic.

&Quot; Optimum Embodiment 2 " Porous ceramic production (red mud 60: mud 40)

Porous ceramics were prepared in the same manner as in Example 1, except that the weight ratio of red mud and minnow was changed to 6: 4 in the step (a) of Example 1.

&Quot; Example 3 " Porous ceramic production (red mud 40: mud 60)

Porous ceramics were prepared in the same manner as in Example 1, except that the mixing weight ratio of red mud and minnow was changed to 4: 6 in the step (a) of Example 1.

Example 4 Production of Porous Ceramic (red mud 20: mud 80)

Porous ceramics were prepared in the same manner as in Example 1, except that the mixing weight ratio of red mud and minnow was changed to 2: 8 in the step (a) of Example 1.

&Quot; Comparative Example 1 "

Porous ceramics were prepared in the same manner as in Example 1, except that the mixing weight ratio of red mud and minnow was changed to 0:10 in step (a) of Example 1.

&Quot; Comparative Example 2 "

Porous ceramics were prepared in the same manner as in Example 1, except that the mixing weight ratio of red mud and wort was changed to 10: 0 in the step (a) of Example 1.

&Quot; Experimental Example 1 " Porosity analysis

The porosity of the porous ceramics prepared in Examples 1 to 4 and Comparative Examples 1 and 2 was analyzed by ASTM-C20 standard test method. The results are shown in FIG.

Referring to FIG. 3, it can be seen that the embodiments of the present invention all have an apparent porosity ranging from 72% to 80%.

&Quot; Experimental Example 2 " Pore size analysis

The pore sizes of the porous ceramics prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were analyzed by a Micro-CT apparatus, and the average particle size (D50) of the pores is shown in Table 2.

division D ₅₀ (占 퐉) Redness 115 Optimum Embodiment 1 156 Optimal Embodiment 2 161 Example 3 172 Example 4 153 Tailings 198

As shown in Table 2, it can be seen that the embodiments of the present invention formed fine pores having a size of 146-172 탆.

&Quot; Experimental Example 3 " Thermal conductivity analysis

The thermal conductivities of the porous ceramics prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were analyzed by a hot-disk instrument. The results are shown in FIG.

Referring to FIG. 4, it can be seen that the thermal conductivity of the optimum embodiment is 0.11-0.18 W / mK.

Although the present invention has been described with respect to a specific embodiment of a method for manufacturing a porous ceramic through red mud and tail spill according to an embodiment of the present invention, it is apparent that various modifications can be made without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be construed as being limited to the embodiments described, but should be determined by equivalents to the appended claims, as well as the following claims.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

Claims (13)

(a) preparing a mixed solution comprising red mats, tailings, ceramic fibers, a water-soluble polymer, and a surfactant;
(b) adding an organic solvent to the mixed solution and freezing it;
(c) thawing the frozen material and subjecting it to a first heat treatment; And
(d) subjecting the first heat treated material to a second heat treatment and sintering,
Wherein the mixed solution of step (a) comprises the red mud and the tail mud at a weight ratio of 1: 0.25 to 0.67.
The method according to claim 1,
The ceramic fiber in the step (a)
Wherein the porous ceramics comprises one selected from the group consisting of silica, alumina, aluminosilicate, aluminoborosilicate, mullite, glass fiber, and combinations thereof.
The method according to claim 1,
The water-soluble polymer of step (a)
Wherein the porous ceramic material is polyvinyl alcohol.
delete The method according to claim 1,
The mixed solution of step (a)
And 6 to 10 parts by weight of ceramic fibers based on 100 parts by weight of the mixture of red mud and tail mud.
The method according to claim 1,
The step (b)
And reducing the mixed solution to 0.05-0.2 atm before adding the organic solvent.
The method according to claim 1,
The freezing of step (b)
Lt; RTI ID = 0.0 > 30 C < / RTI > to < RTI ID = 0.0 > -10 C. < / RTI >
The method according to claim 1,
The first heat treatment in the step (c)
Lt; RTI ID = 0.0 > 40-80 C. < / RTI >
The method according to claim 1,
The second heat treatment in the step (d)
Lt; RTI ID = 0.0 > 300-600 C. < / RTI >
The method according to claim 1,
The sintering in the step (d)
Lt; RTI ID = 0.0 > 1200-1350 C. < / RTI >
Red mud, mineral wool, ceramic fibers, water-soluble polymers, surfactants and organic solvents,
Wherein said red mud and tail mud are contained in a weight ratio of 1: 0.25 to 0.67.
delete 5. A process for the preparation of a compound according to claim 1,
A porous ceramic having an apparent porosity of 72-80% and an average pore size of 146-166 탆.

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