KR101131853B1 - Preparation and coating method of lightweight aggregates using bottom ash and waste glass - Google Patents

Abstract

The present invention is a mixing step of mixing the bottom ash and waste glass and blowing agent, manufacturing a molded body for pelletizing while adding a binder to the mixed raw material, a coating step for coating the surface of the molded body with waste glass powder, and the coated molded body The present invention relates to a method for manufacturing a lightweight aggregate comprising a firing step of firing in a rotary kiln, and can provide a method for producing a lightweight aggregate having excellent thermal insulation and showing low absorption rate and specific gravity, and further, bottom ash and waste glass. Is used as a raw material of light weight aggregate, it can see the dual effect of creating high value added of waste as well as economic effect by reducing and consigning waste disposal cost.

Bottom ash, waste glass, foaming agent, coating, lightweight aggregate

Description

Preparation and coating method of lightweight aggregates using bottom ash and waste glass}

The present invention relates to a method for producing lightweight aggregate, and more particularly, to a method for producing lightweight aggregate having low specific gravity and water absorption using bottom ash and waste glass.

Most of the light weight aggregate among insulation materials used in domestic buildings depend on imports, and sludges (sewage, water purification sludge, etc.) and fly ash, etc. used in the manufacture of light weight aggregates in Korea are fired at a high temperature of 1,100 ℃ or higher. It has the disadvantage of lowering economic efficiency by consuming energy. Therefore, it is necessary to develop raw materials and process technologies having low firing temperature and excellent physical properties such as thermal insulation. In addition, as the demand for light weight due to the recent increase in the height of buildings, the use of lightweight aggregate is gradually increasing in Korea. Accordingly, a number of studies are being carried out by domestic companies to manufacture more lightweight aggregates. Currently, the weight of most of the light weight aggregates used is limited to general light weight aggregates around 1. In addition, most of the light weight aggregate produced has a high water absorption of 10 to 20% or more as shown in Table 1, the absorption control should be made first.

Lightweight aggregate Drying unit weight (kg / m ³ ) origin Water absorption (wt%) Expanded Shale,
Clay, slate 550? 1050 Processed natural products 5? 15 Sinter fly ash 600? 1000 composite 14-24 Expanded Perlite 65-250 Processed natural products 10? 50 Exfoliated
vermiculite 65-250 Processed natural products 20? 35 Brick rubble ? 750 composite 19? 36

However, to date, lightweight aggregates that control the water absorption rate to improve the workability and durability of concrete have not been developed. In addition, the production of lightweight aggregate with specific gravity around 0.5 is limited to some developed countries such as Germany. The lightweight aggregate produced in Germany is manufactured using glass powder, and the softening point and melting point of the glass powder are much lower than the existing raw materials (clay, etc.), and thus have the advantage of lowering the manufacturing temperature (firing temperature) of the lightweight aggregate. Lightweight aggregates made of glass powder also have low water absorption and low water absorption. The pores present in the interior of the lightweight aggregate is composed of open pores and discarded pores, in particular, the interior of the aggregate may be a phenomenon that the size of the pores increases from the surface layer to the inner region. In addition, since the porosity is lower than the general lightweight aggregate, the specific gravity is lowered, and many pores in the aggregate have an advantage of excellent thermal insulation characteristics.

If a large amount of open pores are formed, the water absorption is very large, and thus there is a limit in the expression of physical properties such as thermal insulation properties. In addition, the moisture in the heat insulating material is also characterized by corroding the surface of the interior and exterior that is in contact with the heat insulating material. Therefore, a method for suppressing water absorption and migration by mainly discarding pores present in the material should be derived.

Recently, foaming glass blocks are manufactured using waste glass with low firing temperature and excellent acid resistance, which are used as lining materials for stacks of thermal power plants due to their excellent thermal insulation. However, in consideration of the phenomenon that the block is broken during transportation and work and the work efficiency, it has a disadvantage in that it is manufactured only in a predetermined size or more and has a limitation in the place of use. In addition, the block surface portion is composed of a single pore, but there is a disadvantage that the absorption rate is greatly increased when the connection pores are formed in the block, the glass foam block is difficult to be applied to a lightweight structure. However, when the glass powder is manufactured in a small sphere size, it is possible to increase the amount of waste pores, thereby lowering the absorption rate and excellent thermal insulation, so that it can be used as a general-purpose product.

Meanwhile, about 6 million tons of coal ash is generated annually in 10 domestic thermal power plants, of which about 3.5 million tons (58%) are used as cement substitutes and the remaining 2.5 million tons (42%) are landfilled in nearby landfills. Although fly ash (fly ash) in coal ash is recycled in a considerable amount, floor ash (bottom ash) is difficult to utilize, so all of it is disposed of in landfills, but this is also a difficult time for disposal.

Therefore, it is necessary to recycle the bottom ash and waste glass, which are wastes, and it is necessary to develop eco-friendly lightweight aggregates with low economical efficiency and low water absorption by lowering plastic energy than existing lightweight materials.

It is an object of the present invention to provide a method for producing lightweight aggregate having low specific gravity and water absorption while using bottom ash and waste glass.

Method for producing a lightweight aggregate of the present invention is a mixing step of mixing the bottom ash and waste glass and blowing agent; A molded article manufacturing step of pelletizing while adding a caking additive to the mixed raw materials; Coating the surface of the molded body with waste glass powder; And firing the coated molded body in a rotary kiln.

In the method for producing a lightweight aggregate of the present invention, the bottom ash and the waste glass in the mixing step is 0.1: 99.9 to 30: 70 by weight, the mixing of 0.1 to 10 parts by weight of the blowing agent based on 100 parts by weight of the bottom ash and waste glass. It features.

In the manufacturing method of the lightweight aggregate of the present invention, the blowing agent is characterized in that any one selected from calcium carbonate, graphite and iron trioxide.

In the manufacturing method of the lightweight aggregate of the present invention, the molded product manufacturing step is characterized in that 1 to 40 parts by weight of a binder is added to 100 parts by weight of the mixed raw materials of the mixing step.

In the manufacturing method of the lightweight aggregate of the present invention, the binder is characterized in that the water glass aqueous solution.

In the manufacturing method of the lightweight aggregate of the present invention, the molded article manufacturing step is to adjust the interval between the stirring blade and the bottom surface of the pelletizer according to the particle size of the predetermined molded body and to rotate the stirring blade for 1 to 100 minutes at 50 ~ 1000 rpm It is characterized by.

In the manufacturing method of the light weight aggregate of the present invention, the coating step is characterized by coating 1 to 60 parts by weight of waste glass powder in 100 parts by weight of the molded body.

The firing step in the production method of the light weight aggregate of the present invention is characterized in that the firing at 0.1 ~ 60 minutes at 600 ~ 1200 ℃ rotary kiln.

Light weight aggregate of the present invention is produced by the above method, specific gravity 0.6 ~ 1.2, characterized in that the moisture absorption of less than 5%.

Light weight aggregate of the present invention is characterized in that the particle size is 0.1 ~ 30 mm.

The present invention can provide a method for producing a lightweight aggregate having excellent insulation and low absorption rate and specific gravity, and furthermore, in the case of using bottom ash and waste glass as a raw material of lightweight aggregate, it is possible to reduce waste recycling cost and recycle. In addition to the economic effects of this, there is a dual effect of creating high added value of waste.

Method for producing a lightweight aggregate of the present invention is a mixing step of mixing the bottom ash and waste glass and blowing agent; A molded article manufacturing step of pelletizing while adding a caking additive to the mixed raw materials; Coating the surface of the molded body with waste glass powder; And a firing step of firing the coated molded body in a rotary kiln.

The bottom ash and waste glass in the mixing step of the present invention is 0.1: 99.9 to 30: 70 weight ratio, preferably 10: 90 to 25: 75 weight ratio. If the bottom ash is less than the lower limit, the moisture absorption of the lightweight aggregate is too high, and if the upper limit is exceeded, the specific gravity exceeds 1.2.

The foaming agent is 0.1 to 10 parts by weight, preferably 0.2 to 4 parts by weight, more preferably 0.25 to 2 parts by weight based on 100 parts by weight of the bottom ash and the waste glass. If the foaming agent content is less than the lower limit, the specific gravity is too high due to insufficient porosity inside the lightweight aggregate, and if the upper limit is exceeded, even if the lightweight aggregate is coated with waste glass, the fracture strength is lowered and the waste is easily opened due to the crushing. This will be increased. The latter may be mixed even if the light aggregate is coated with the waste glass. The blowing agent of the present invention is preferably calcium carbonate, graphite and iron trioxide (Fe ₂ O ₃ or hematite).

The molded article manufacturing step of the present invention is added 1 to 40 parts by weight of the binder, preferably 20 to 35 parts by weight to 100 parts by weight of the mixed raw material of the mixing step. It is preferable to use water glass aqueous solution as a caking additive. Water glass aqueous solution is used that 20 to 90% by weight, preferably 40 to 80% by weight of water glass.

In the manufacturing method of the molded body of the present invention, the interval between the stirring blades and the bottom surface of the pelletizer is adjusted according to the particle size of the predetermined molded body, and the stirring blade is 1 to 100 minutes at 50 to 1000 rpm, preferably 200 to 500 rpm, Preferably it can be produced by rotating for 5 to 20 minutes.

The coating step of the present invention includes 1 to 60 parts by weight of waste glass powder, preferably 10 to 50 parts by weight, more preferably 25 to 45 parts by weight, in 100 parts by weight of the molded body. If the waste glass powder for coating is less than the lower limit, the specific gravity is low, but the water absorption rate is high. If the waste glass powder for coating is above the upper limit value, the moisture absorption rate is low, but the specific gravity is high.

The firing step of the present invention is baked in a rotary kiln at 0.1 to 60 minutes, preferably 1 to 30 minutes at 600 to 1200 ° C, preferably at 800 to 1000 ° C.

The light weight aggregate of the present invention prepared by the above method has a specific gravity of 0.6 to 1.2 or less than 5% of a water absorption rate, and preferably satisfies both the specific gravity and water absorption rate conditions. Light weight aggregate of the present invention has an average particle size of 0.1 ~ 30 mm.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are merely to illustrate the present invention, but the content of the present invention is not limited thereto.

[Example]

The bottom ash used in this experiment was generated from Dangjin Coal Fired Power Plant, and used waste glass generated from sheet glass processing.The chemical composition of bottom ash was SiO ₂ as shown in Table 2 below. 43.5 wt%, Al ₂ O ₃ 22.4 wt%, Fe ₂ O ₃ 5.15% by weight, the waste glass was confirmed to be composed of 71.1% by weight of SiO ₂ , 13.1% by weight of Na ₂ O, 8.79% by weight of CaO.

ingredient SiO ₂ Al ₂ O ₃ CaO MgO Fe ₂ O ₃ K ₂ O Na ₂ O SO ₃ Cl Ig-loss Bottom ash 43.5 22.4 0.99 0.42 5.15 0.62 0.43 0.42 0.01 24.4 Waste glass 71.1 1.24 8.79 3.65 0.65 0.35 13.1 0.30 4.76 0.66

To 100 parts by weight of bottom ash, which is the main raw material, and 1 part by weight of calcium carbonate and graphite were added as blowing agents, respectively, and the mixture was mixed in a ball mill for 6 hours. In preparing the script, 0.9 g (30%) of 30% of the mixed raw material was used. The prepared globules were dried for 24 hours in a 100 ℃ dryer and then heated up to 900 ℃ by 5 ℃ per minute and then maintained for 10 minutes to produce a lightweight aggregate by cooling in an electric furnace. Table 3 shows the physical properties of the lightweight aggregate prepared in this way.

division Bottom ash Waste glass CaCO ₃ Graphite importance Absorption rate (%) Fracture Strength (㎏f) Preparation Example 1 10 90 One - 0.67 7.48 125 Preparation Example 2 20 80 One - 0.89 6.24 155 Preparation Example 3 30 70 One - 1.14 4.71 315 Production Example 4 40 60 One - 1.53 4.58 335 Production Example 5 10 90 - One 1.13 6.32 240 Production Example 6 20 80 - One 1.26 6.21 295 Preparation Example 7 30 70 - One 1.68 4.88 370 Preparation Example 8 40 60 - One 1.75 3.74 385

As in Experimental Examples 1 to 4, in the case of lightweight aggregate added with 1 part by weight of calcium carbonate as a foaming agent, the specific gravity increased as the content of bottom ash increased from 10 parts by weight to 40 parts by weight based on 100 parts by weight of bottom ash and waste glass. And, the water absorption was confirmed to decrease. It was also confirmed that the fracture strength value increased.

As shown in Table 3, if more than 30 parts by weight of bottom ash is added to the total amount of bottom ash and waste glass, the specific gravity increases to 1 or more as the content of bottom ash having a high softening point increases and the foaming capacity decreases. I could confirm that.

In Preparation Examples 5 to 8, graphite was used instead of calcium carbonate as the blowing agent. The specific gravity increased with increasing the content of the bottom ash, and the absorption rate decreased. In addition, the failure strength increased.

In Examples 1 to 8, CaCO 3 and graphite, which are blowing agents, were measured by TG-DTA (DTG-60H and SHIMADZU), respectively, as shown in FIGS. 1 and 2. In Preparation Example 1, it was confirmed that the calcium carbonate was foamed while reducing the weight of 40% or more while generating carbon dioxide gas as in Scheme 1 at a softening point of 760 to 800 ° C. or higher.

CaCO _{3 - →} CaO + CO ₂

In the case of graphite, the softening point is similar, but foaming proceeds slowly with a 20% weight loss up to 1200 ° C. The reaction scheme of graphite is shown in Scheme 2.

C → CO ₂

30 parts by weight of an aqueous glass solution of water (water glass: distilled water = 70: 30, weight ratio) was added as a binder for 10 minutes at 300 rpm for the stirring blade rotation speed in a pelletizer based on 100 parts by weight of the raw materials mixed in the same formulation as in Table 4. 25 mm spherical shaped bodies were made by addition. The molded article was baked at 900 ℃ for 10 minutes in a rotary kiln to produce a lightweight aggregate.

division Bottom ash Waste glass CaCO ₃ Graphite importance Absorption rate (%) Production Example 9 10 90 One - 0.57 7.21 Preparation Example 10 20 80 One - 0.81 6.09 Preparation Example 11 30 70 One - 0.98 4.71 Preparation Example 12 40 60 One - 1.31 4.60 Preparation Example 13 10 90 - One 0.87 7.89 Preparation Example 14 20 80 - One 1.21 5.72 Preparation Example 15 30 70 - One 1.52 4.24 Preparation Example 16 40 60 - One 2.03 4.01

Preparation Examples 9 to 12 were used to replace the bottom ash and waste glass by each content to add calcium carbonate as a blowing agent. As in Preparation Example 11, 30 parts by weight of the bottom ash was added to 100 parts by weight of the bottom ash and the waste glass. It was confirmed that the light weight aggregate was less than 1, and the water absorption gradually decreased from 7.21%.

In Examples 13 to 16, graphite was added as a foaming agent, and 1 wt% of graphite was added as in Preparation Example 13. As in Example 13, 10 parts by weight of bottom ash was added to 100 parts by weight of the bottom ash and waste glass in total. When the specific gravity was less than 1, the water absorption was gradually decreased from 7.89%.

The light weight aggregate manufactured in the rotary kilns of Preparation Examples 9 to 16 was found to have a lower specific gravity and a higher absorption rate than the light weight aggregate manufactured in the electric furnaces of Preparation Examples 1 to 8. This is the foam from below the glass softening point proceeds as the electric furnace is slowly elevated temperature is reduced is the foam volume of at least the glass softening temperature, and therefore if the firing in the rotary kiln CO ₂ gas in accordance with the heating rate shortening is to momentarily generate The expansion pressure generated at this time is higher than when the temperature increase rate is determined to be more effective in forming pores of lightweight aggregate.

Table 5 shows 20 parts by weight and 80 parts by weight of bottom ash and waste glass, respectively, and a water glass aqueous solution (water glass: distilled water = 70: 30, weight ratio) as a caking agent for 10 minutes at 300 rpm in a pelletizer. Was prepared by adding 30 parts by weight of a 25 mm spherical molded body, and then coated by adding 1 to 50 parts by weight of waste glass powder with respect to 100 parts by weight of the molded body, respectively. It shows the physical properties of the aggregate.

Waste Glass Addition Coating thickness (㎛) Fracture Strength (㎏f) importance Water absorption rate (%) One 15 155 0.63 6.02 10 130 180 0.71 5.54 20 320 195 0.88 3.21 30 580 205 0.95 2.09 40 740 210 1.02 1.24 50 980 220 1.05 1.17

When the waste glass powder was coated up to 40 parts by weight with respect to 100 parts by weight of the molded body, the specific gravity and water absorption were significantly reduced, and the result was similar to 40 parts by weight over 50 parts by weight.

1 is a graph measuring CaCO3 by TG-DTA.

2 is a graph measuring graphite by TG-DTA.

Claims (10)

In mixing the bottom ash, waste glass and foaming agent, the bottom ash and waste glass is 0.1: 99.9 to 30: 70 by weight, the mixing of 0.1 to 10 parts by weight of the blowing agent with respect to 100 parts by weight of the bottom ash and waste glass step; A molded article manufacturing step of pelletizing while adding 1 to 40 parts by weight of a binder to 100 parts by weight of the mixed raw material; A coating step of coating 1 to 60 parts by weight of the waste glass powder on 100 parts by weight of the molded body; And And a firing step of firing the coated molded body in a rotary kiln. delete The method of claim 1, wherein the blowing agent is any one selected from calcium carbonate, graphite and iron trioxide. delete According to claim 1, wherein the binder is a method for producing a lightweight aggregate, characterized in that the water glass aqueous solution. According to claim 1, wherein the molded article manufacturing step is characterized in that the spacing between the stirring blade and the bottom surface of the pelletizer according to the particle size of the predetermined molded body and rotating the stirring blade for 1 to 100 minutes at 50 ~ 1000 rpm Method of manufacturing lightweight aggregate. delete The method of claim 1, wherein the firing step is a method for producing a lightweight aggregate, characterized in that the firing in a rotary kiln 0.1 ~ 60 minutes at 600 ~ 1200 ℃. delete delete

Images