KR100959158B1 - The method of liquid hehaviol in the process fo the production of sintered dust/clay body and the brick produced by using such method - Google Patents

Abstract

The present invention, by adding a control for controlling the behavior of the liquid phase during the sintering of the sintered body produced by mixing the dust and clay, and by adjusting the content of the dust and the control material to improve the fire resistance of the sintered body and the sintered body according to the characteristics of the liquid phase It relates to a method of controlling the behavior of the liquid phase during the manufacture of dust clay-based sintered body to reduce the defective rate of the brick produced by using the same and a brick manufactured using the same.

To this end, the present invention is characterized in that the alumina is mixed and mixed in the process of forming a sintered body by mixing dust and clay which is a waste to manufacture a dust-clay-based brick, characterized in that the behavior of the liquid phase generated during the production of the sintered body is controlled To provide a method of controlling the behavior of the liquid phase during the manufacture of dust clay-based sintered compact and a brick manufactured using the same.

Dust, Clay, Sintered Body, Liquid Behavior

Description

FIELD OF THE LIQUID HEHAVIOL IN THE PROCESS FO THE PRODUCTION OF SINTERED DUST / CLAY BODY AND THE BRICK PRODUCED BY USING SUCH METHOD}

The present invention relates to a method of controlling the behavior of a liquid phase generated during the manufacture of dust clay-based sintered compacts and bricks produced using the same.

In detail, the present invention, by adding a control for controlling the behavior of the liquid phase during the sintering of the sintered body produced by mixing the dust and clay, by adjusting the content of the dust and the control material to improve the fire resistance of the sintered body according to the change in the characteristics of the liquid phase and It relates to a method of controlling the behavior of the liquid phase during the manufacture of dust clay-based sintered body to reduce the defective rate of the brick manufactured by using the sintered body and a brick manufactured using the same.

Most industrial waste was generally disposed of in landfills. The landfill of such industrial wastes has been exposed to serious problems such as the limitation of landfill and environmental pollution such as soil and groundwater contamination due to leachate discharged from landfill.

In order to solve this problem, many researches are being conducted on technologies for stabilizing industrial waste and recycling resources. As one of such recycling resources, a process of mixing bricks with electric arc furnace dust (EAF dust) is proposed.

At this time, dust containing a large amount of heavy metals is classified as designated waste, and such dust is mixed with clay because it contains a large amount of flux components such as zinc oxide (ZnO) and iron oxide (Fe ₂ 0 ₃ ). Mixing induces liquid phase sintering to lower the sintering temperature and to improve the strength of the sintered body (sintered body to be made of brick).

In particular, when the dust and clay are mixed very uniformly, the heavy metal components of the dust are melted together in the siliceous solution in the clay, and ultimately, the heavy metal components are bonded and stabilized inside the silicate glass of the network structure.

In contrast to the above advantages, since the sintered product having a lot of fluxes has a narrower firing temperature, when the mass production is carried out using a continuous furnace having a relatively large temperature gradient, a problem of increasing the defective rate of the product is exposed.

Therefore, in order to decrease the sintering temperature and increase the strength of the sintered compact by increasing the amount of dust added in the sintered compact, the necessity of appropriately controlling the behavior of the flux, ie, the liquid phase, has emerged.

Thus, the present invention is to mix the additives for controlling the liquid phase characteristics when manufacturing the dust-clay sintered body to control the behavior of the liquid phase, physical properties such as microstructure, apparent density, water absorption, compressive strength of the sintered body It is an object of the present invention to provide a method of controlling the behavior of a liquid to be excellent and a brick manufactured using the same.

In order to achieve the above object, the present invention has the following features.

To this end, the present invention, in order to form a sintered compact by mixing dust and clay, which is a waste in order to manufacture a dust-clay brick, by mixing and forming alumina (Al ₂ O ₃ ), the behavior of the liquid phase generated during the sintered compact manufacturing It is characterized in that it is controlled.

Here, the sintered compact is formed by mixing 65% by weight to 90% by weight of clay, 5% by weight to 20% by weight of dust, and 5% by weight to 15% by weight of alumina based on 100% by weight of the total.

At this time, if the dust is less than 5% by weight, the amount of dust is too small to reduce the strength of the sintered body, when the composition is more than 20% by weight heavy metal components of the dust excessively in the siliceous solution in the clay Melting results in an unstable structure inside the mesh silicate glass.

In addition, when the alumina is less than 5% by weight, the pores formed in the sintered body is non-uniform, so that the behavior of the liquid phase is not controlled. The hardness increases while the brittle strength decreases.

Therefore, the content of clay is determined in accordance with the content of dust and alumina.

The sintered compact as described above is pulverized with dust and clay in a four-minute method using a harvester, pulverized into a fine powder of 40 mesh or less through a pulverizer, and mixed with the fine powder and reagent grade alumina in a mixer to form a composition. Wow; The composition was uniaxially formed at a pressure of 150 MPa through a molding machine, dried in a dryer at 90 ° C./24 h, maintained at 1100 ° C.-1300 ° C. for 2 hours at a temperature rising rate of 10 ° C./min in a sintering furnace, and then cooled by sintering. It is prepared by performing; forming.

At this time, if the holding temperature is less than 1100 ℃ in the sintering process, the sintering power is lowered and the brittle strength is low. If the holding temperature is higher than 1300 ℃, the internal pores of the sintered body are trapped and the compressive strength is lowered as the porous microstructure is formed. .

In the present invention, a sintered body is manufactured by the above process and the sintered body can be processed to obtain a brick having excellent physical properties.

As described above, the present invention, when manufacturing the dust-clay-based sintered body is added to the alumina to control the liquid-phase characteristics, by optimizing the content of the alumina is added to the sintered body and the brick manufactured using the shape retaining ability at high temperature The effect is to improve.

In addition, the present invention increases the density of the sintered body and the brick manufactured using the same by adding the alumina, lowers the absorption rate, increases the expression temperature of the compressive strength and at the same time improves the mechanical strength to obtain excellent physical properties. There is one effect.

By carrying out the present invention as described above to produce a specimen, and to measure the physical properties and the degree of fire resistance of the specimen will be described in detail with reference to the accompanying drawings.

<Production of Psalms>

Red clay and dust to be prepared from the specimens were prepared by their respective composition as shown in Table 1.

In this example, the specimen is 5% by weight, 10% by weight, 15% by weight with respect to the total 100% by weight, as shown in Table 2, for which 0, 5%, 10%, 15% by weight of alumina It was prepared by sintering at 1200 ℃ / 2h.

<Measurement of physical properties of specimens>

1. Microstructure

The microstructure was observed by SEM (JSM-5600, JEOL Co.), and the specimens were etched in 10% hydrofluoric acid (HF) solution for 1 sec for easy observation.

2. Density and Absorption Rate

The prepared specimens were measured by the archimedes method.

3. Compressive strength

The compressive strength was measured by preparing cylindrical specimens with a diameter of 10 mm and a height of 10 mm. The average values for five specimens were obtained.

4. Crystallographic confirmation

X-ray (D / MAX 2500 / PC) diffraction analysis was performed and measured. In this case, the measurement conditions are Cu-k _α line, 40 kV / 40 mA, scan speed = 0.1 ° <2θ <80 °.

5. Fire resistance

The fire resistance test was performed by preparing cone shaped specimens in accordance with ASTM D-1857-87. At this time, the size of the cone specimen was fixed with an equilateral triangle having a side length of 6.4 mm as the base and having a height of 19.0 mm. In addition, the cone specimen was fixed at an 80 ° or 90 ° angle on the support mold. In particular, the material of the support has alumina and red clay in a 7: 3 ratio to minimize the reaction with the cone.

In addition, there are four types of fire resistance-related temperatures: the temperature at which the cone set at 80 ° starts to bend T _I , and the temperature at which the bean is bent at 80 ° to reach the bottom is T _R (fire temperature) is referred to as the temperature at which the base 2 is of a hemispherical shape that is multiple of T _S, and, the temperature T _H when the vertical cone is melted when the height of the semi-spherical shape, such as a side length. These fire-related temperatures were measured by wearing a high-temperature observation goggles through a quartz window installed on the wall of the furnace, the temperature rising rate was 5 ℃ / min.

<Measurement result>

1. Microstructure

Compared to the microstructure of the 100 wt% clay sintered body (FIG. 1A), the specimen of 10D-0A (FIG. 1B) contains macropores of various sizes, including macropores of about 150 μm in size, and has a nonuniform microstructure. . The reason that the dust-added specimen is porous with a non-uniform microstructure is because a lot of flux component in the dust generates a liquid phase during the firing process, and the liquid phase surrounds the specimen and makes the inside of the specimen into a reducing atmosphere. Thereafter, when the inside of the specimen is reduced, the iron oxide releases oxygen gas, and at the same time, the liquid phase is captured to make the microstructure porous.

However, it could be seen that the specimens in which alumina was added to the 10D-based specimens (FIG. 1C, 10D-5A, FIG. 1D, 10D-10A, and FIG. 1E, 10D-15A) dissipated the macropores and maintained a uniform microstructure. In particular, it can be seen that the microstructure of the 10D-15A specimen in which 15% by weight of alumina is added is very uniform.

2. Density and Absorption Rate

The apparent density and water absorption rate of the specimens sintered at 1250 ° C./2h and 1300 ° C./2h by adding alumina in the range of 0 to 15 wt% in the 5D series specimens show the same results as in the graphs of FIGS. 2A and 2B.

The apparent density increases as the amount of alumina added increases, as shown in FIG. 2A. In addition, the absorption rate decreases as the amount of alumina added in the specimen increases. In particular, the apparent density and water absorption as described above could be clearly seen at 1300 ℃.

As shown in the microstructure of FIG. 1, this result was found to occur because when the alumina is added, the macropores are reduced and the microstructure is changed to a dense microstructure.

3. Compressive strength

Figure 3 is a graph showing the results of measuring the compressive strength according to the temperature and composition of the 10D series specimens.

Referring to the drawings, the 10D-0A specimen without alumina increases the compressive strength with the initial temperature and has the highest strength value at 1150 ° C. For example, the strength of specimens sintered at 1150 ° C was increased by 200% compared to 1050 ° C. However, at higher sintering temperatures, the compressive strength was lowered. This is the temperature at which sintering densification occurs due to the generation of an appropriate liquid phase, and the higher temperature is higher than the porosity because internal pores are trapped and cannot escape to the outside. It has a microstructure, and it can be seen that the compressive strength is lowered accordingly.

On the contrary, the alumina-added specimens were found to have a temperature at which the maximum compressive strength was obtained was 1200 ° C. increased by 50 ° C. compared to the specimens without the alumina added. In addition, as the amount of alumina added increases, the maximum compressive strength increases. For example, the compressive strength of the 10D-15A specimen increased by 330% compared to the 10D-0A specimen among the specimens sintered at 1200 ° C.

As a result, it is common that the strength of the specimen is increased by increasing the sintering temperature within an appropriate temperature range, but the highest strength at 1150 ° C indicates that the internal pores are bloated at a temperature higher than that, resulting in a lighter weight of the specimen. As you can see the strength was lowered.

4. Crystallographic confirmation

4A and 4B are graphs of the results of sintering 10D series specimens at 1100 ° C. and 1275 ° C., respectively, and performing an analysis through an X-ray (D / MAX 2500 / PC) diffraction analyzer. In the figures, o indicates mullite, o indicates quartz, o indicates hematite, o indicates hercinite, o and corundum.

At a low sintering temperature of 1100 ° C. as shown in FIG. 4A, even though alumina is added to the specimen, quartz and alumina do not react with each other and exist as respective phases. However, the sintering temperature of 1275 ℃, as shown in Figure 4b disappears quartz phase of the sample of the alumina were added, Hershey nitro _{(hercynite) (FeO · Al 2} O 3) , and mullite _{(mullite) (3Al 2 O 3} · 2SiO 2) The phenomenon of synthesizing was confirmed.

As a result, it was found that the alumina consumed quartz and iron oxide at the sintering temperature of 1275 ° C., and the specimen without alumina was transferred to cristobalite mica at 1275 ° C. due to homogeneous abnormalities.

At this time, the mullite phase synthesis of the specimen to which the alumina was added was confirmed by scanning electron microscopy (SEM). Figure 5 is a detailed view of the microstructure of the specimen made of the mullite phase synthesis.

Referring to the drawings, it was found that the specimen was sintered at 1200 ° C. by adding 15% by weight of alumina to the 10D-based specimens, and it was found that the needle-like crystals in the specimens were formed in the form of typical mullite particles.

5. Fire resistance

As described above, when the liquid phase of the specimen is excessively generated, bonding such as deformation of the specimen shape occurs. In particular, the oxide forming the silicate melt is classified into a base oxide and an acid oxide. Basic oxides are metal element oxides that act as network modifiers when forming glass, and acidic oxides serve as network formers. Therefore, when there are many basic oxides in a melt, the viscosity of a melt will reduce.

The basicity of the melt is defined by the following equation.

Basicity = base / acid ratio = (R ₂ O + RO) / (SiO ₂ + Al ₂ O ₃ + TiO ₂ )

Here, R = Group 1 or Group 2 elements, for example, sodium oxide (Na ₂ O), potassium oxide (K ₂ O), calcium oxide (CaO), magnesium oxide (MgO).

6 is a graph showing the basicity of the specimen by the equation (1).

Referring to the drawings, a specimen having a large amount of dust added has a high basicity, and when alumina is added in each specimen series, the basicity is lowered. That is, dust increases the basicity of the body, and thus reduces the viscosity of the liquid phase generated. On the other hand, it can be seen that alumina can increase the viscosity of the melt because it reduces the basicity of the body.

7 is a graph showing the results of the fire resistance and melting experiments performed on the 20D series of specimens.

In particular, FIG. 7A shows each refractory degree or melting temperature according to the amount of alumina added, and shows that all of the refractory and melting temperatures are increased except for the temperature of some T _I when alumina is added. In addition, Figure 7b shows the T _R temperature for the amount of alumina added to the 10D and 20D series specimens, the specimen series having a large amount of dust has a lower refractory temperature.

As can be seen from the figure, the fire resistance temperature, T _R was found to be higher than the 10D series of the 20D series specimens. In addition, the specimens in the same series had a higher T _R value as the amount of alumina added increased. That is, the addition of alumina does not increase the specimen fire resistance only by the addition of a high refractory material, it can be seen that the specimen shape is maintained to a high temperature because the amount of melt produced by dust is reduced and the viscosity is increased.

At this time, the viscosity of the melt has an inverse relationship with the temperature, Figure 8 is a graph showing this.

As such, the relationship between the various refractory and melting temperatures of all the specimens used in this example was T _I <T _R <T _S <T _H. The temperature T _CV has a value similar to approximately T _S as defined in FIG. 8. In particular, at this temperature the melt transitions from Bingham Plastics to Newtonian flows.

In addition, the high viscosity such that the viscosity of the liquid phase formed in the specimen does not impair the specimen shape, that is, the highest temperature T _CV having Bingham plastic properties increases with the amount of alumina added. At this time, the addition of alumina means that the temperature at which the specimen shape change occurs is increased. Alternatively, the viscosity is sufficiently high at a temperature below that, which means that the shape defect of the specimen does not occur.

In addition, the refractory temperature increases 10D series specimens from 1290 ℃ to 1600 ℃ by alumina increases. In addition, in the 20D series specimens, the fire resistance of the specimen without alumina is increased from 1230 ° C. to 1450 ° C. by adding alumina (15 wt%).

1a to 1e is an enlarged view of the microstructure of the specimen prepared by the present invention.

Figure 2a, Figure 2b is a graph of the density, absorption rate of the specimen prepared by the present invention.

Figure 3 is a graph of compressive strength of the specimen prepared by the present invention.

4A and 4B are X-ray diffraction graphs of the specimens prepared according to the present invention.

5 is an enlarged view of the mullite phase synthetic microstructure of the specimen prepared by the present invention.

6 is a basicity graph of the specimen prepared by the present invention.

Figure 7a, Figure 7b is a fire resistance temperature graph of the specimen prepared by the present invention.

Figure 8 is a graph of the melt viscosity and temperature of the specimen prepared by the present invention.

Claims (4)

In the process of forming a sintered compact by mixing dust and clay, which are wastes, in order to manufacture a dust-clay brick, alumina is mixed and manufactured so that dust clay sintered compact is manufactured so as to control the behavior of a liquid generated during sintered compact manufacturing. Method of controlling the behavior of medium liquid phase. The method of claim 1, The sintered compact is dust clay, characterized in that the mixture of 65% to 90% by weight of clay, 5% to 20% by weight of dust, and 5% to 15% by weight of alumina Method for controlling behavior of liquid phase during the manufacture of sintered compacts. The method according to claim 1 or 2, Collecting dust and clay by a four-minute method using a harvester, pulverizing it into fine powder of 40 mesh or less through a pulverizer, and mixing the fine powder and reagent grade alumina in a mixer; The composition was uniaxially formed at a pressure of 150 MPa through a molding machine, dried in a dryer at 90 ° C./24 h, maintained at 1100 ° C.-1300 ° C. for 2 hours at a temperature rising rate of 10 ° C./min in a sintering furnace, and then cooled by sintering. Method of controlling the behavior of the liquid phase during the manufacture of dust clay-based sintered body comprising the step of forming. delete

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