KR101577661B1 - Fly-ash Light Weight Aggregation and Manutacturing Method thereof - Google Patents

Abstract

The present invention relates to an artificial lightweight aggregate (lightweight aggregate) having excellent physical properties without performing a firing process at a high temperature by using fly ash and an alkali activator, which are industrial wastes ), And a lightweight aggregate produced by such a method.
In the present invention, a method for producing an artificial lightweight aggregate using fly ash, comprising: spraying and mixing an alkali activator comprising an aqueous solution having a concentration of 6 to 12M selected from NaOH and KOH into fly ash powder; Making a mixture of the fly ash powder and the alkali activator into a granular shaped body using a granulator; Characterized in that the granulated green body is cured at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours to form a spherical artificial lightweight aggregate having a particle size of 5 mm or less and a specific gravity of 1.5 to 2.0, An artificial lightweight aggregate produced thereby is provided.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fly ash lightweight aggregate using an alkali activating agent and a method for producing the fly ash light weight aggregation and manufac- turing method,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lightweight aggregate that is made artificially, and more specifically, by using fly ash as an industrial waste and an alkali activating agent, A lightweight aggregate having excellent physical properties without performing a process, and a lightweight aggregate produced by such a method.

Efforts have been made to utilize fly ash, which is an industrial waste generated from a thermal power plant, as an industrial material. As one of the recycling methods of fly ash, there is an attempt to produce lightweight aggregate using fly ash, for example Korean Patent Application No. 1990-17394 (Publication No. 1995-1668). However, in the conventional method of manufacturing fly ash lightweight aggregate to date, including the prior art disclosed in the above-mentioned domestic patent application, a firing process that is carried out at a high temperature of about 800 to 1200 degrees centigrade is indispensably required.

In the process of burning at such a high temperature, a lot of energy is consumed, and as a result, industrial lightweight aggregate is produced by using industrial waste. However, contrary to this, there is a contradiction situation in that it consumes considerable energy and is not environmentally friendly.

Korean Patent Registration No. 1995-1668 (Patent Application No. 1990-17394) (1995. 02. 28. Announcement).

The present invention has been developed in order to overcome the limitations of the prior art as described above. Specifically, artificial lightweight aggregate having excellent physical properties is manufactured by using fly ash, which is an industrial waste, The present invention also provides a lightweight aggregate manufacturing method and a lightweight aggregate manufactured by the method, wherein the lightweight aggregate has environmental advantages such as energy saving and production cost reduction as well as recycling.

In order to achieve the above object, the present invention provides a method for producing an artificial lightweight aggregate using fly ash, comprising the steps of selecting at least one of NaOH and KOH as an alkali activator, Spraying on ash powder and mixing; Making a mixture of the fly ash powder and the alkali activator into a granular shaped body using a granulator; The granular shaped body is cured at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours to form a spherical artificial lightweight aggregate having a particle size of 5 mm or less and a specific gravity of 1.5 to 2.0, do.

In order to achieve the above object, the present invention provides an artificial lightweight aggregate produced by the above-described production method, wherein at least one of NaOH and KOH is selected to have a concentration of 6 to 12 M, Powder mixture; There is provided a spherical artificial lightweight aggregate characterized by having a particle size of 5 mm or less and a specific gravity of 1.5 to 2.0 by being made into a granular molded body by a granulator and being cured at a temperature of 50 to 90 degrees for 6 to 24 hours .

In the production method of the present invention and the artificial lightweight aggregate produced by the above method, when the weight of the fly ash powder is 100, the weight of the fly ash powder and the alkali activator is 0.2 To 0.3, and when the mixture of the fly ash powder and the alkali activator is made into a granular shaped body using a pelletizer, the rotary disk provided in the pelletizer has a slope of 60 to 75 degrees from the vertical And the rotation speed of the disk is set to 15 to 35 rpm, and the disk may be rotated for 5 to 15 minutes.

According to the present invention, it is possible to produce an artificial lightweight aggregate having excellent physical properties by using fly ash, which is an industrial waste, without undergoing a firing process at a high temperature. Therefore, according to the present invention, not only a waste recycling aspect but also an environment-friendly advantage of energy saving and production cost reduction and economical useful effect are exhibited.

1 is a graph showing the specific gravity of a mixture of fly ash powder and an alkali activator according to the molar concentration of the alkali activator according to the present invention.
Fig. 2 is a photograph showing a sphere-shaped formed body made using a pellet in the present invention.
FIG. 3 to FIG. 6 are graphs showing average particle sizes of the green compacts, average particle sizes of the green compacts according to the rotation speed of the disks, absorption ratios and specific gravities of the green compacts according to the inclined angles of the disks, FIG. 8 is a graph showing the relationship between the specific gravity and the water absorption rate of the molded article according to the rotational speed of the disk. FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Although the present invention has been described with reference to the embodiments shown in the drawings, it is to be understood that the technical idea of the present invention and its essential structure and operation are not limited thereby.

In the present invention, lightweight aggregate is produced by using fly ash, and fly ash is activated by using an alkali activator made of an aqueous alkali solution, whereby a lightweight aggregate which satisfies the physical properties required as a lightweight aggregate without performing a high- And a lightweight aggregate produced by the method.

Specifically, in the method of producing a lightweight aggregate according to the present invention, the fly ash powder is granulated while spraying an alkali activator made of an aqueous alkali solution.

First, the fly ash powder is prepared and sprayed with an alkali activator made of an aqueous alkali solution to be mixed with the fly ash powder. In the present invention, the alkali activating agent to be mixed with the fly ash powder is an aqueous solution prepared by selecting at least one of NaOH and KOH to have a concentration of 6 to 12M.

Fly ash is a material containing alumino silicate, which is rich in Si and Al. NaOH and KOH to make the concentration of the alkali solution to be in the range of 6 to 12 M. When the fly ash is mixed with the alkali activator as described above, the bonding of Si-O-Al-O ≪ / RTI > is produced.

In the above formula (1), z is a constant of 1 to 3, M represents Na or K, an alkali component contained in the alkali activator, and n represents a degree of polymerization.

The reaction products produced by the above polymerization reaction have fast condensation characteristics and exhibit high early strength. 1 is a graph showing the specific gravity (vertical axis of the graph) for a mixture of fly ash powder and an alkali activator according to the molar concentration of the alkali activator (abscissa of the graph). In FIG. 1, NaOH aqueous solution, and the points indicated by squares are for the case where the alkali activating agent is made of aqueous KOH solution. In FIG. 1, the abscissa indicates the mole concentration and the ordinate indicates the specific gravity. FIG. 1 shows an angle of inclination of the disk of the granulator, which will be described later, from the vertical direction to 70 degrees, a rotation speed of 20 rpm, Curing time is 10 minutes and curing is for 24 hours at a temperature of 90 degrees Celsius.

As shown in FIG. 1, the specific gravity of the mixture of the fly ash powder and the alkali activator increases as the molar concentration of the alkali activator increases, but when the molar concentration of the alkali activator is less than 6M, sufficient polymerization reaction does not occur, The strength becomes less than the strength that can be used as the aggregate. Therefore, in the present invention, the molar concentration of the alkali activator mixed with the fly ash powder should be 6M or more. Since the NaOH and KOH used in the alkali activating agent are expensive materials, when the molar concentration of the alkali activating agent mixed with the fly ash powder exceeds 12M, the economical efficiency is significantly lowered. Therefore, in the present invention, The molarity of the alkali activating agent is adjusted to 12M or less.

In the present invention, in mixing the fly ash powder and the alkali activator as described above, when the weight of the fly ash powder is 100, the weight ratio of the alkali activator composed of the aqueous solution is 0.2 to 0.3. If the weight of the fly ash powder is less than 1: 0.2, that is, the weight of the fly ash powder is 100 and the weight of the alkali activator is less than 0.2, the amount of the liquid is too small to form the fly ash powder into particles On the contrary, when the weight of the fly ash powder is greater than 1: 0.3, that is, when the weight of the fly ash powder is 100 and the weight of the alkali activating agent is more than 0.3, The strength of the lightweight aggregate is greatly reduced. Therefore, in the present invention, the mixing ratio of the alkali activating agent to the fly ash powder is 1: 0.2 to 1: 0.3 as a weight ratio.

In the present invention, an alkali activator composed of an aqueous alkaline solution is sprayed and mixed with the fly ash powder to form a sphere-shaped formed body using a pelletizer. FIG. 2 shows a photograph showing a sphere-shaped formed body using an assembling machine. The assembling machine itself is already known, and when the disk is rotated while spraying a liquid onto the powder, the powder and the liquid are mixed, Is formed. In the production of a molded article using the granulator, the amount of the powdery raw material, the amount of the liquid raw material, the inclined angle of the rotating disk, the rotational speed of the disk, and the molding time due to the rotation of the disk, It has a big influence.

In the present invention, in order to make the lightweight aggregate composed of the alkali activator and the fly ash powder made of an aqueous alkaline solution have satisfactory physical properties without the sintering process, , The disk of the granulator is installed so as to have an inclination of 60 to 75 degrees from the vertical, the disk is rotated at a rotation speed of 15 to 35 rpm and the disk is rotated for 5 to 15 minutes to manufacture a spherical granular shaped body.

When the disc angle is less than 60 degrees, the average particle size of the molded body to be produced exceeds 5 mm and becomes excessively large. When the angle of the disc exceeds 75 degrees, the average particle size Is reduced to 3.4 mm or less, but the absorption rate is increased and additional molding time is required. Accordingly, in the present invention, the molded body is manufactured in a state in which the disk of the granulator is inclined at an angle of 60 to 75 degrees from the vertical.

On the other hand, as the rotational speed of the disk increases, the particle size of the formed body increases. Therefore, the rotational speed of the disk should be 35 rpm or less. If the rotational speed of the disk is less than 15 rpm, It is not smoothly performed. Therefore, the rotational speed of the disk should be 15 rpm or more.

Also, the change of major physical properties such as particle size, specific gravity, absorption rate, etc. of the molded body according to molding time using a granulator is relatively small compared to other factors. Therefore, the rotation time of the disk is set to 5 minutes or more, and if it exceeds 15 minutes, the molded body is not grown any more, so the disk is rotated for 15 minutes or less.

FIGS. 3 to 6 are graphs showing average particle sizes (FIG. 3) of the formed bodies according to the disk angles (FIG. 3), average particle sizes of the shaped bodies according to the rotating speed of the disks Fig. 5 is a graph showing the relationship between the absorbency and specific gravity (Fig. 5) of the molded article and the absorbency and specific gravity (Fig. 6) of the molded article according to the rotational speed of the disc. In FIG. 3, the horizontal axis represents the angle of the disk, and the vertical axis represents the average particle size of the molded article. In FIG. 4, the abscissa is the rotation speed (rpm) of the disk, and the ordinate is the average particle size (mm) of the formed body. In FIG. 5, the abscissa represents the inclined angle of the disk, and the ordinate represents the absorption rate (absorption / unit%) and the specific gravity, respectively. In FIG. 6, the abscissa is the rotational speed (rpm) of the disk, and the ordinate is the absorption rate (absorption / unit%) and specific gravity, respectively. Figs. 3 to 6 show the results of using a 9M NaOH aqueous solution as the alkali activating agent, curing the molded article at a rotational speed of 20 rpm for 10 minutes at a temperature of 90 deg. C for 24 hours It is the result of the time.

In the present invention, after forming a granular shaped body having a particle size of 5 mm or less by using a granulator under the above conditions, it is cured at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours to obtain a spherical shape having a specific gravity of 1.5 to 2.0 and a water absorption rate of 13% Of artificial lightweight aggregate.

FIG. 7 is a graph showing the change of the crushing rate of the artificial lightweight aggregate according to the curing conditions. The granular shaped bodies produced through the manufacturing process of the present invention are shown at 50, 60, 70, 80, 7 shows graphs of the fracture rate of the molded body when curing was carried out at a temperature of 3 hours, 6 hours, 12 hours, 18 hours, 24 hours and 30 hours respectively and then a load of 40 tons was applied. In FIG. 7, the horizontal axis represents the curing temperature (temp) and the vertical axis represents the crushing rate.

7, the artificial lightweight aggregate produced by curing at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours has a crushing ratio of 23 to 30, which is similar to that of the lightweight aggregate produced through the firing process according to the prior art %). However, if the curing temperature is less than 50 ° C, the strength improvement can not be expected even if the curing time is increased. Therefore, in order to produce an artificial lightweight aggregate having a good crushing ratio in the present invention, the granular shaped body produced by the granulator is cured at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours. As described above, in the present invention, it is possible to efficiently produce spherical artificial lightweight aggregate having a specific gravity of 1.5 to 2.0 and a water uptake of 13% or less without performing a high-temperature firing step at all.

When the artificial lightweight aggregate according to the present invention, which has a water absorptance of 13% or less, is used for concrete without performing a high-temperature sintering process, improvement in workability and improvement in pressure transportability of the pump are expected.

Claims (4)

In the fly ash powder,
0.2 to 0.3 parts by weight of an alkali activator composed of an aqueous solution having a concentration of 6 to 12 M was selected by mixing at least one of NaOH and KOH with respect to 100 parts by weight of the fly ash powder,
Forming a mixture of the fly ash powder and the alkali activating agent in a granular form having a particle size of 5 mm or less by using a granulator;
The granular shaped body is cured at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours to produce a spherical artificial lightweight aggregate having a specific gravity of 1.5 to 2.0 and a water absorption of 13% or less.
delete The method according to claim 1,
When the mixture of the fly ash powder and the alkali activator is granulated using a granulator, the rotary disk provided in the granulator is installed so as to have an inclination of 60 to 75 degrees from the vertical, and the rotation speed of the disk is 15 to 35 rpm, and the disk is rotated for 5 to 15 minutes.
A mixture of an alkali activator and fly ash powder comprising an aqueous solution prepared by selecting at least one of NaOH and KOH to a concentration of 6 to 12 M,
A spherical artificial lightweight aggregate satisfying a particle size of 5 mm or less, a specific gravity of 1.5 to 2.0, and an absorptance of 13% or less, obtained by curing at a temperature of 50 to 90 degrees Celsius for 6 to 24 hours after molding into a granular molded body by a granulator.

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