KR100591060B1 - Light weight aggregate composition and method for manufacturing light weight aggregate using the same - Google Patents

Abstract

The present invention relates to a light weight aggregate composition and a method for manufacturing a light weight aggregate using the same, wherein the light weight aggregate of the present invention is 100 to 20 parts by weight of organic sludge, and the loss of ignition by unburned carbon as a main caking agent is 10 to 20% by weight. 4 to 100 parts by weight of ash and 2 to 20 parts by weight of auxiliary caking agent.

According to the present invention, the specific gravity is low by using inorganic waste such as fly ash having 10-20% by weight of ignition loss due to organic sludge which has been treated indiscriminately by conventional landfill and ocean dumping and insufficient utilization of unburned carbon. It is possible to produce a high value-added lightweight aggregate having excellent absorption and strength characteristics.

Lightweight aggregate. Organic sludge. Fly ash. Abandoned tailings. Stone powder sludge. Molded body.

Description

Lightweight aggregate composition and manufacturing method of light weight aggregate using same

The present invention relates to a lightweight aggregate composition and a method for manufacturing a lightweight aggregate using the same, and more particularly, to a lightweight aggregate composition containing a large amount of organic sludge which is a waste generated in a wastewater treatment plant and a method for producing a lightweight aggregate using the same.

In general, organic sludge, especially sewage sludge, is a solid secondary environmental pollutant generated when removing particulate, colloidal, and dissolved pollutants contained in sewage during the treatment of sewage. There is a tremendous amount of 1.2 million tons per year in the terminal treatment plant, and the sewage pipe maintenance and additional installation of sewage treatment facilities are continuously performed to protect water resources.

Conventionally, organic sludge has been treated by embedding in a fixed landfill. In this case, since the organic sludge has a high moisture content, landfilling is not smooth, causing problems in ground compaction, and it is very difficult to secure a landfill site because it causes leachate and odor. For this reason, from 1 July 2003, direct landfilling under high water content has been banned.

Although the above-mentioned prohibition of direct landfilling of organic sludge is intended to be converted to recycling and intermediate treatment of organic sludge, the treatment of organic sludge is currently being converted to ocean dumping at a low treatment cost. In Korea, it is sprayed on the high seas in two places on the East Sea and one in the West Sea. However, when the 96 Protocol related to the London Anti-Dumping Convention enters into force, marine dumping will be banned, so that efficient measures for its disposal are urgently needed.

Incineration, drying, and organic fertilization have been proposed as a method of treating organic sludge as a way to overcome the problems of direct landfill and ocean dumping.

The incineration method was started in Korea in the early 90's with a small treatment capacity, and incineration methods have been considered in most fluidized and rotary phases. However, the organic sludge has a problem that the treatment cost is very high since the initial installation of the treatment facility requires a lot of energy in operation because the low water content is low because of high moisture content of about 70% and low organic matter content.

In addition, a dry-incineration linkage system incorporating the incineration method and the drying method has been proposed, and as the waste wood generated in the city is used as an energy source in the drying step, the treatment cost is reduced by almost half compared to the case of using only the incineration method. Harvested. Nevertheless, incineration method or dry-incineration linkage method has a problem of treatment of incineration ash remaining after incineration. Specifically, incineration ashes contain heavy metals and dioxins, which require special treatment, which requires expensive equipment, time and effort.

In addition, many studies have been made on the recycling of organic sludge for agricultural use. However, as described above, since organic sludge contains a considerable amount of harmful substances, it has many limitations in its use.

On the other hand, lightweight concrete is widely used to reduce dead weight of buildings, heat insulation, and sound insulation, and many studies have been made on artificial lightweight aggregates used for the light concrete. Generally, raw materials that can be manufactured from artificial light weight aggregates include expanded clay, sail, slate, and the like, and the chemical composition of these raw materials is within the range of easy expansion during firing. However, unlike the clays scattered throughout the country, expanded clay, which is a raw material that satisfies the easy expansion conditions in Korea, exists in some areas of the Chungnam budget and in some areas of Gangwon and Chungbuk, but not in small amounts. In the same photosphere, the chemical composition is so severe that it is very difficult to actually commercialize. In addition, there is a limit to the raw material harvesting has been devised to add an organic or inorganic blowing agent to non-expandable ceramic raw materials, and attempted to manufacture by artificially formulating a chemical composition suitable for expansion, but was not easily tried due to the economic disparity.

The present invention has been made to solve the above problems, an object of the present invention is to provide a lightweight aggregate composition using organic sludge difficult to process and recycle, and a method for producing a lightweight aggregate having excellent physical properties using the same.

Another object of the present invention is to manufacture by using inorganic waste resources, such as fly ash, low utilization rate of clay, waste tailings and stone powder sludge containing very small or large amount of organic matter, due to the large loss of ignition by unburned carbon. It is to provide a lightweight aggregate composition with excellent physical properties while minimizing the cost and a method for producing a lightweight aggregate using the same.

In order to solve such technical problems, the lightweight aggregate composition according to the present invention has a fly ash of 4 to 100 parts by weight based on 100 parts by weight of organic sludge, the loss of ignition by unburned carbon as a main caking agent, 10 to 20% by weight, and It consists of 2 to 20 parts by weight of auxiliary caking agent.

In addition, in the light weight aggregate composition of the present invention, it is preferable that 0.1 to 8 parts by weight of waste gypsum is further included with respect to the dry weight of the composition.

In addition, in the light weight aggregate composition of the present invention, the auxiliary caking agent is preferably one or two or more selected from clay, waste tailings and stone sludge.

Method for producing a lightweight aggregate according to the present invention is a paste manufacturing step of producing a paste having a water content of 20 to 40% by weight by homogeneously mixing and drying the composition according to any one of claims 1 to 3; A molded article manufacturing step of manufacturing a molded article having a predetermined shape with the paste; A molded article drying step of drying the molded article at a water content of 20% by weight or less; A foam firing step of preparing the aggregate by foaming the molded body in a kiln and foaming at a temperature of 1,180 to 1,300 ° C .; And a cooling step of cooling the aggregate. It is made, including.

In addition, in the method for manufacturing lightweight aggregate of the present invention, the manufacturing method is preferably before or after the molded body drying step, it is preferable to coat the molded body with waste gypsum.

In addition, in the manufacturing method of the lightweight aggregate of the present invention, the molded article manufacturing step, by extrusion molding the paste to produce a prismatic or columnar primary molded body, and put the primary molded body in a rotating drum to waste gypsum It is preferable that the coating is made of a method of producing a spherical secondary molded body while coating with a.

In addition, in the manufacturing method of the lightweight aggregate of the present invention, the foam firing step, the temperature of the preheating portion up to 600 ℃ to 10 ~ 30 ℃ / min, the temperature rising zone portion from 600 ℃ to the temperature to start foaming 30 ~ 100 It is preferable to heat up at ° C / min.

In addition, in the manufacturing method of the light weight aggregate of the present invention, the cooling step, it is preferable to cool the aggregate at a cooling rate of 50 ~ 200 ℃ / min to release to the atmosphere at a temperature of 200 ~ 300 ℃.

Hereinafter, the lightweight aggregate composition according to the present invention will be described in detail.

The lightweight aggregate composition is composed of organic sludge, fly ash as a main binder, auxiliary plaster and waste gypsum as a blowing agent.

The organic sludge is preferably one or two or more selected from the group consisting of sewage sludge, purified sludge, dyed sludge, paper sludge, sugar sludge and leather sludge, but other organic sludges may be used.

The fly ash used as the caking agent is a composition for securing moldability, reducing moisture content, and expressing strength, and the loss of ignition by unburned carbon in fly ash generated after coal combustion in a thermal power plant or a cogeneration plant is 10 to 20. Preference is given to using as high as% by weight.

Of course, even if the loss of ignition by unburned carbon is less than 10% by weight can be used naturally. However, since the fly ash is currently recycled to concrete admixtures, etc., its utilization rate is very high and sold at a high price, which increases the manufacturing cost when used as a material for lightweight aggregate.

On the other hand, fly ash, which has a high ignition loss due to the unburned carbon of 10 to 20% by weight, is used as a concrete admixture, and thus the use of the fly ash has a very small effect of reducing the amount of air by adsorbing entrained air bubbles of concrete. to be. When fly ash having a high ignition loss due to such unburned carbon is 10-20% by weight in the production of light weight aggregates as in the present invention, rather, the carbon is oxidized when the light weight aggregate is calcined to carbon dioxide gas, which is very advantageous for foaming. By the combustion of carbon, not only the atmosphere in the kiln is formed in a reducing atmosphere, which is a favorable condition for foaming, but also has the advantage of significantly reducing the firing energy. Further, as described above, since the loss of ignition due to unburned carbon is significantly lower than that of less than 10% by weight, it is more meaningful in terms of being able to recycle the less-used material. There is also an advantage that it is easy to secure and costs are significantly lower.

When the content of fly ash having a loss of ignition by the unburned carbon is 10 to 20% by weight is less than 4 parts by weight based on 100 parts by weight of organic sludge, the specific gravity is lowered, but the absorption is higher and the strength is significantly lowered. There is this. On the contrary, in the case of more than 100 parts by weight, the inorganic amount is increased and the specific gravity is increased, so the utility as a light weight aggregate is inferior.

The auxiliary binder is similar to the fly ash to improve the cohesive force to secure the formability, and is mixed for reducing moisture content and strength, etc., is composed of one or two or more selected from clay, waste tailings and stone sludge. .

In general, clay used as a ceramic raw material is clay which does not contain organic matter. However, in the present invention, the clay used as an auxiliary caking agent is scattered all over the country, so it is not a big problem to use a clay containing a small amount or a large amount of organic materials that are easy to secure, as well as construction residue, but rather to secure materials. And for cost reduction. In addition, the clay can be used in the same manner as the general plastic clay brick manufacturing process without the need for grinding. In addition, the stone powder sludge is generated during quarrying and processing, and may be used as it is in a dehydrated cake state after precipitation. That is, these clays and stone powder sludges can be used as long as they contain 60 to 70 wt% of SiO ₂ and 15 to 25 wt% of Al ₂ O ₃ .

The waste tailings are mining by-products, and have a specific surface area of 2,000 cm 2 / g or more as an atomized material in the process of crushing or pulverizing and sorting to separate and sort out useful minerals, and have a SiO ₂ 60 to 70% by weight, Al ₂ O ₃ , It can be used if it contains 5 to 15% by weight of CaO and Fe ₂ O ₃ .

When the mixing amount of the auxiliary binder is less than 2 parts by weight based on 100 parts by weight of the organic sludge, the caking force is low and the moldability is inferior. On the contrary, if it exceeds 20 parts by weight, foaming and sintering are not performed properly because the content of the organic sludge is relatively reduced.

Waste gypsum used as a blowing agent and surface coating in the present invention is produced in a large amount during the desulfurization process and phosphoric acid, hydrofluoric acid, boron, titanium production process, and can be used if the CaSO ₄ component contains 70% by weight or more.

Of course, foaming is achieved even if the waste gypsum is not mixed, but by adding it, foaming can be induced more actively, which is advantageous in lightening aggregates. When the waste gypsum is mixed in an amount exceeding 8 parts by weight with respect to the dry weight of the composition, since foaming is excessive, there is a problem in that a crack occurs on the surface and the water absorption becomes significantly high. In the case of the waste gypsum, the decomposition temperature is high, similar to the aggregate production temperature, and thus the effect is high as a preferable blowing agent, but a treatment facility for SO ₃ generation is required.

Hereinafter, a method for manufacturing lightweight aggregate according to the present invention will be described in detail.

The composition is mixed homogeneously and dried to prepare a paste. When the total water content of the paste is more than 40% by weight or less than 20% by weight, molding itself is impossible, so the total water content is preferably 20 to 40% by weight. More preferably, it is 20 to 30% by weight. It is organic sludge and stone dust sludge that play an absolute role in the moisture content of the paste. For example, in case of using organic sludge in the dehydrated cake state and / or stone sludge, the other components constituting the composition can be controlled by using a low water content. That is, by mixing organic sludge or / and stone sludge in a dehydrated cake state with fly ash, clay and waste tailings having a low moisture content, a large agglomerated state is formed, and then crushed into small granules and dried. A paste having a water content of 20 to 40% by weight can be easily produced. In addition, clay and waste tailings may be used in a state of containing some water after some drying in the natural state, and in the case of waste gypsum can also be used in a state containing water. In addition, when the total moisture content exceeds 40% by weight after homogeneously mixing and drying the composition, the total water content may be adjusted to 40% by weight or less by adding the mixed and dried composition powder. In addition, when the composition is added to the conveyor, it is preferable to obtain a homogeneous mixture through a circulating compression roller mixer, a screw, and the like by sequentially inputting each of the compositions instead of collectively.

The paste prepared as above forms a molded article having a certain shape. Specifically, the paste is extruded to prepare a prismatic or columnar primary molded body, and the primary molded body is put into a rotating drum to produce a spherical secondary molded body. In more detail, the primary molded body is formed by cutting the sample compressed by the screw of the extruder or the like into an appropriate size while being extruded by a mold having a predetermined diameter. At this time, the discharge rate is changed depending on the viscosity of the paste, the shape and size of the primary molded body is changed depending on the cutting speed, it is preferable that the diameter is 2 ~ 10mm. The primary molded body thus formed is put into a rotating drum to produce a spherical secondary molded body. However, when the drum rotates in the primary moldings are stuck to each other, the aggregate having the desired shape and size can not be obtained. Therefore, in order to prevent this, the surface of the primary molded body is coated with waste gypsum and then put into a rotating drum to produce a spherical secondary molded body, or the primary molded body is directly put into a rotating drum, and then the fine powder of waste gypsum is applied. It can also be spherical and rolled simultaneously with coating. In this case, the waste gypsum used is different from the waste gypsum forming the lightweight aggregate composition, it is preferable to use a powder in a dried state, it is preferable to coat the waste gypsum fine powder by applying a thickness of 50 ~ 200㎛ on the surface of the primary molded body. . If the thickness of the coating layer is less than 50㎛ can not achieve the above object, if the coating is more than 200㎛ because the heat is not properly transferred to the inside of the molded body during baking, the central temperature of the molded body is necessary for sintering There is a risk that the cooling is discharged without reaching the temperature, for this reason there is a disadvantage that the firing temperature must be increased.

In addition, the coating by the waste gypsum, as described above, in addition to preventing the phenomenon of sticking between the primary molded bodies, there is also an effect of preventing fusion in the firing process described later.

In addition, the internal structure is dense by the rolling operation in the rotating drum for 5 to 15 minutes.

The secondary molded body is dried at a water content of 20% by weight or less, more preferably 10% by weight or less at a temperature of 200 ° C or less, and then poured into a kiln to foam firing. If the drying temperature is higher than 200 ° C, organic matter inside the molded body may be burned. If the moisture content exceeds 20% by weight, water vapor inside the molded product may be released to the outside due to rapid heat, causing cracks on the surface. Because it is.

In addition, the injection amount of the molded body is not only directly related to the productivity of the kiln, but also has a deep relationship with the atmosphere in the furnace when manufacturing artificial lightweight aggregate. Aggregate is influenced by the atmosphere of the whole kiln, but in particular, because it is directly affected by the atmosphere in the vicinity of the kiln, there is a risk of sintering in an oxidizing atmosphere because the small amount of molded product increases the chance of receiving oxygen. The greater the probability that the aggregates will be buried in the kiln, the less chance there is to be supplied with oxygen. Therefore, a reducing atmosphere is naturally formed, which is favorable for foaming. However, aggregates buried in the kiln may not be properly heated and sinter incompletely. . Therefore, the input amount of the raw material in the kiln is preferably 8 to 12% of the volume in the furnace.

The foam firing is carried out for several minutes, preferably 5 to 15 minutes at a temperature of 1,180 ~ 1,300 ℃ the baking zone. If the sintering temperature is less than 1,180 ℃, the aggregate shows high absorption rate and specific gravity because sintering and foaming is not done properly.On the contrary, if it is over 1,300 ℃, the value of aggregate is low because it shows oversintering, over-foaming and partial melting There is also a problem of rising costs such as fuel costs.

On the other hand, artificial lightweight aggregate is a material using decomposition and expansion, recrystallization due to heat, it is necessary to control the heat flow inside the aggregate by giving the appropriate temperature and time. If it is not properly controlled, the temperature of aggregate is cooled and discharged without reaching the temperature required for sintering, or irregular and large pores are formed due to gas decomposition due to rapid temperature rise, resulting in poor quality of aggregate such as strength. .

In the present invention, the temperature rises up to the baking zone, the preheat zone to prevent the formation of irregular and large pores by the rapid combustion of organic matter with a rapid temperature rise, and the rapid entry into the plastic zone through rapid heat in the aggregate inside A temperature zone section is provided to prevent gas escape. This optimizes the quality of the aggregate, including the effect of suppressing the generation of large amounts of gas at the highest temperatures and providing the time needed for recrystallization.

Specifically, it is preferable that the temperature is gradually increased to 10 to 30 ° C./min up to 600 ° C., which is a preheating part, and the temperature is increased at a temperature of 30 to 100 ° C./min from 600 ° C., which is a temperature rising zone, to the temperature at which foaming starts.

At this time, when the kiln is a rotary kiln, the temperature increase rate can be controlled by adjusting the rotational speed and the gradient inside the kiln, and in particular, in the preheating zone by narrowing the length and diameter of the temperature increase zone where rapid heating is required. It is possible to quickly enter the firing zone, and in the case of a tunnel kiln, it is possible to control the temperature increase rate by adjusting the inlet speed of the split gate foil on the rail.

In the baking zone, by maintaining a predetermined time after reaching the maximum temperature to induce uniform pore distribution and stable sintered structure formed in the light weight aggregate, the strength is formed, it is preferable to maintain for 5 to 15 minutes. However, by changing the holding temperature and time it is possible to adjust the degree of foaming to control the specific gravity and absorption rate of lightweight aggregate.

Finally, the aggregate is cooled, the strength of the aggregate depends on the cooling rate after sintering. Generally, the slower the cooling rate, the more the internal stress of the aggregates is increased by removing the irregular stress of the aggregate to form a stable internal sintered foam structure, and the progress of sintering stabilization and the recrystallization of the glass phase are generated. However, considering the productivity, the aggregate discharged from the kiln is very hot, so the temperature must be lowered through quenching so that subsequent processes such as conveying conveyors, sorting through sieves, and storing in silos can be connected separately. It is preferable to perform quenching, and it is advantageous in terms of economics to recover this heat and reuse it in a dryer or the like. In view of this, it is preferable to cool to 50 ~ 200 ℃ / min and discharge into the atmosphere at a temperature of 200 ~ 300 ℃.

Hereinafter, the configuration and operation of the present invention through the embodiment will be described in detail.

The components and physical properties of the organic sludge, fly ash, clay, calcined sludge and waste tailings used in all the following examples are shown in Tables 1-3.

Specifically, the water, organic matter and inorganic matter content of the organic sludge are shown in Table 1 below.

In addition, the chemical composition for the inorganic material after calcining the organic sludge at 600 ℃ is shown in Table 2 below.

In addition, the chemical composition of fly ash, clay, stone sludge, waste tailings and waste gypsum is shown in Table 3.

<Example 1>

To 100 parts by weight of sewage sludge in a dehydrated cake state, a composition consisting of 50 parts by weight of fly ash and 5 parts by weight of clay was mixed and dried to prepare a paste having a water content of 20 to 30% by weight.

After the paste was manufactured into a cylindrical primary molded article having a diameter of 8 mm by an extrusion molding machine, the primary molded article was put into a rotating drum-type molding machine, and rolled for 8 minutes while applying a fine powder to a waste gypsum as a coating to prepare a spherical secondary molded article. . At this time, the thickness of the coated waste gypsum was set to 150㎛. After drying the coated secondary molded product to a water content of 10% or less at a temperature of 200 ℃ or less, and put the dried molded product into a kiln to enter a preheating zone 600 ℃ at a temperature increase rate of 15 ℃ / min, After heating at 600 ℃ to 60 ℃ / min in a large section and firing for 10 minutes at the temperature of 1,220 ~ 1,250 ℃, cooling at 150 ℃ / min and releasing it into the atmosphere at 250 ℃ It was prepared.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 1.46, the absorption rate was 11.4%, and the result of 10% fine grain fracture test was 15.6tons.

<Example 2>

With respect to 100 parts by weight of the sewage sludge in the dehydrated cake state, except that the composition is mixed with 4 parts by weight of fly ash, 5 parts by weight of clay and 5 parts by weight of waste gypsum based on the dry weight of the material. Light aggregate was prepared in the same conditions and order.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 0.53, the absorption rate was 12.9%, and the result of 10% fine grain fracture test was found to be 3.6ton.

<Example 3>

Except for 100 parts by weight of sewage sludge in the dehydrated cake state, except that 50 parts by weight of fly ash, 5 parts by weight of clay and 5 parts by weight of waste gypsum were added to the dry weight of the material, Light aggregate was prepared in the same conditions and order.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 1.23, the absorption rate was 13.3%, and the result of 10% fine grain fracture test was 14.8tons.

<Example 4>

With respect to 100 parts by weight of sewage sludge in a dehydrated cake state, except that 100 parts by weight of fly ash and 5 parts by weight of clay were added to the composition by adding 5 parts by weight of waste gypsum to the dry weight of the material. Light aggregate was prepared in the same conditions and order.

As a result of testing the lightweight aggregate obtained as above, the specific gravity was 1.57, the absorption rate was 14.6%, and the result of 10% fine grain fracture test was found to be 16.5ton.

Comparative Example 1

In order to grasp the degree of quality characteristics of the light weight aggregates obtained in the above example, quality tests of light weight aggregates imported from Germany (Liaipor Co., Ltd.), Spain (Arita Co., Ltd.) and Japan (Mesalite Co., Ltd.) were carried out. The results are shown in Table 4 below.

As compared with Examples 2 to 4, as the amount of fly ash is increased, it is disadvantageous in terms of specific gravity and water absorption, and the strength tends to increase. However, as a whole, as can be seen in Table 4, it was confirmed that the lightweight aggregate produced by the above-described embodiment according to the present invention is superior in terms of absorption and strength compared to the imported lightweight aggregate.

In addition, in comparison with Examples 1 and 3, when the waste gypsum is mixed, the specific gravity decreases, while the absorption rate and strength tend to increase. Therefore, it is possible to choose whether to mix the waste gypsum as needed.

Comparative Example 2

With respect to 100 parts by weight of sewage sludge in the dehydrated cake state, except for mixing 1 part by weight of fly ash, lightweight aggregate was prepared in the same conditions and order as in Example 3.

As a result of testing the lightweight aggregate obtained as above, specific gravity was 0.73, water absorption was 23%, and the result of 10% fine grain fracture test was found to be 1.8ton.

As such, as the amount of fly ash is reduced, the physical properties of the aggregates are significantly reduced.

Comparative Example 3

With respect to 100 parts by weight of sewage sludge in the dehydrated cake state, except for mixing 110 parts by weight of fly ash, lightweight aggregate was prepared in the same conditions and order as in Example 3.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 1.83, the absorption rate was 16%, and the result of 10% fine grain crushing test showed 9.8tons.

As the amount of fly ash is increased, the amount of organic matter is relatively decreased, and the amount of inorganic matter is increased, so that the sintering of the aggregate is not performed properly, so that the specific gravity of the aggregate is increased and the strength is decreased.

<Comparative Example 4>

A light weight aggregate was prepared in the same conditions and order as in Example 3, except that 10 parts by weight of waste gypsum was mixed with respect to the dry weight of the material.

As a result of testing the lightweight aggregate obtained as above, specific gravity was 0.52, water absorption was 23.2%, and the result of 10% fine grain crushing test was 2.5tons.

As the amount of waste gypsum increased to 10 parts by weight, the foaming was excessive, so that some cracks occurred on the surface, and the absorption rate was significantly increased and the strength was also decreased.

Example 5

10 parts by weight of fly ash, 3 parts by weight of clay, 8 parts by weight of clay powder sludge, and 3 parts by weight of waste gypsum, based on the dry weight of the material, were dried and dried to obtain a water content of 25 to 35% by weight. Phosphorous paste was prepared.

After the paste was manufactured into a cylindrical primary molded article having a diameter of 5 mm by an extrusion molding machine, the primary molded article was put into a rotating drum-type molding machine and rolled for 8 minutes while applying a waste plaster fine powder as a coating to prepare a spherical secondary molded article. . At this time, the thickness of the coated waste gypsum was 200 μm. After drying the coated secondary molded product to a water content of 15% or less at a temperature of 100 ℃ or less, and then put the dried molded product into a kiln to enter a preheating zone 600 ℃ at a temperature increase rate of 20 ℃ / min, After entering at a temperature increase rate of 30 ℃ / min from 600 ℃, which is a large section, calcining for 10 minutes at a temperature of 1,250 ~ 1,280 ℃, cooling it at 50 ℃ / min and releasing it into the atmosphere at a temperature of 300 ℃ Prepared.

As a result of testing the lightweight aggregate obtained as above, specific gravity was 0.76, water absorption was 13.6%, and the result of 10% fine grain crushing test was 4.2tons.

Comparative Example 5

Except that the primary molded body was not coated with waste gypsum, lightweight aggregate was prepared in the same conditions and order as in Example 5.

In this case, the discharged aggregates produced severe fusion between the aggregates and the aggregates, and thus, the aggregates were not able to be used as aggregates, and the quality test was also impossible.

<Example 6>

100 parts by weight of the papermaking sludge in the dehydrated cake state, 40 parts by weight of fly ash, 10 parts by weight of clay, 7 parts by weight of waste tailings, and 5 parts by weight of waste gypsum, based on the dry weight of the material, and dried to obtain a water content of 20 to 30% by weight. Phosphorous paste was prepared.

After the paste was manufactured into a cylindrical primary molded body having a diameter of 10 mm by an extrusion molding machine, the primary molded body was put into a rotating drum-type molding machine, and rolled for 10 minutes while applying a fine powder of waste gypsum as a coating agent to prepare a spherical secondary molded body. . At this time, the thickness of the coated waste gypsum was 200 μm. After drying the coated secondary molded product to a water content of 10% or less at a temperature of 150 ℃ or less, and put the dried molded product into a kiln to enter a temperature preheating zone of 30 ℃ / min up to 600 ℃, and the temperature rise After entering the heating rate of 600 ℃ to 60 ℃ / min, which is a large section, it is calcined for 10 minutes at a temperature of 1,250 ~ 1,280 ℃, and then cooled at 100 ℃ / min and discharged into the atmosphere at a temperature of 200 ℃. It was prepared.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 1.15, the absorption rate was 11.5%, and the result of 10% fine grain fracture test was 10.6tons.

Comparative Example 6

After preparing the molded body, the light aggregate was prepared in the same conditions and order as in Example 6, except that it was added directly into the kiln without drying. At this time, the water content of the molded product was 28.8%.

The lightweight aggregate obtained as described above was severely cracked on the surface and it could be confirmed that the aggregate of some split shape is discharged. This is because when the water is introduced into the kiln, the water vapor inside the molded body escapes to the outside due to rapid heat generation and causes cracks on the surface.

<Example 7>

With respect to 100 parts by weight of sewage sludge in a dehydrated cake state, a composition consisting of 10 parts by weight of fly ash, 5 parts by weight of clay and 3 parts by weight of waste gypsum based on the dry weight of the material was mixed and dried to obtain a paste having a water content of 20 to 30% by weight. Prepared.

After the paste was manufactured into a cylindrical primary molded article having a diameter of 8 mm by an extrusion molding machine, the primary molded article was put into a rotating drum-type molding machine, and rolled for 8 minutes while applying a waste plaster fine powder as a coating to prepare a spherical secondary molded article. . At this time, the thickness of the coated waste gypsum was 100 μm. After drying the coated secondary molded product to a water content of 20% or less at a temperature of 200 ℃ or less, and put the dried molded product into a kiln at a temperature rising rate of 15 ℃ / min up to 600 ℃ of the preheating zone, It enters at a heating rate of 600 ℃ to 70 ℃ / min and fires at the firing temperature of 1,230 ~ 1,270 ℃ for 10 minutes, then cools it at 200 ℃ / min and releases it into the air at 250 ℃. Aggregate was prepared.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 0.63, the absorption rate was 12.4%, and the result of 10% fine grain crushing test was 4.3tons.

Comparative Example 7

Except that the firing temperature was set to 1,120 ~ 1,150 ℃, a lightweight aggregate was prepared in the same conditions and procedures as in Example 7.

As a result of testing the lightweight aggregate obtained as above, specific gravity was 1.8, water absorption was 23.2%, and 10% fine grain fracture test was found to be 2.1ton.

As such, it can be seen that the quality of the aggregate is lowered at 1,180 ° C. or less because sintering and foaming are not sufficiently performed.

<Comparative Example 8>

Except that the firing temperature was set to 1,300 ~ 1,350 ℃, the lightweight aggregate was prepared in the same conditions and procedures as in Example 7.

As a result of testing the lightweight aggregate obtained as described above, the specific gravity was 1.17, the water absorption was 18.2%, and the 10% fine-grain fracture test showed 5.2tons.

As such, when the firing temperature is set to 1,300 ° C. or more, oversintering and partial melting occur, thereby lowering the value of aggregate.

Comparative Example 9

After entering into the kiln, it entered the preheating zone 600 ℃ at a heating rate of 35 ℃ / min, and entered the heating zone at a heating rate of 600 ℃ to 110 ℃ / min and fired at a temperature of 1,230 ~ 1,270 ℃ for 5 minutes. Except for the point, lightweight aggregate was prepared in the same conditions and order as in Example 7.

As a result of testing the lightweight aggregate obtained as above, specific gravity was 1.72, water absorption was 22%, and the result of 10% fine grain crushing test was 1.9tons.

In this way, if the preheating temperature and the temperature increase rate were reduced and the firing time was shortened, heat could not be properly transferred into the aggregate, resulting in incomplete sintering.

Comparative Example 10

After entering into the kiln, it entered the preheating zone 600 ℃ at a temperature increase rate of 5 ℃ / min, and entered the heating zone at a temperature increase rate of 600 ℃ to 25 ℃ / min and calcined at 1,230 ~ 1,270 ℃ for 20 minutes. Except for the point, lightweight aggregate was prepared in the same conditions and order as in Example 7.

As described above, when the temperature increase rate was lowered and the firing time was increased, the aggregates showed severe fusion phenomena, which made it impossible to manufacture aggregates and was also very disadvantageous in terms of productivity.

Experimental Example 1

The dissolution properties of the aggregates prepared as in Examples 1 to 7 were measured according to the EPA method (EPT) and the Korean Waste Process Test Method (KSLT).

The experimental results are shown in Table 5 below. Where the unit is ppm and ND (Not Detected) indicates that no test results were detected.

As shown in Table 5, most of the heavy metals were not detected, and a small amount of the detected amount was within the allowable range, and the impact on the environment was very small.

Experimental Example 2

In order to evaluate the usability of the lightweight aggregate according to the present invention to the non-concrete lightweight concrete, the lightweight aggregate prepared by Example 2 was manufactured as shown in Table 6 below to carry out unit volume weight and compressive strength test. The results are shown in Table 6.

In Table 6, W / C shows the weight ratio of the mixed water (W) to cement (C), and the light weight aggregate used a specific gravity of 0.53 and a granulation rate of 4.6 with a maximum dimension of 6 mm. As shown in Table 6, concrete incorporating lightweight aggregate according to the present invention has a unit volume weight of about 600 kg / m 3, and the 28-day compressive strength is 3.8 to 5.1 MPa, which is an existing non-structural lightweight product ALC (autoclaved lightweight concrete) It shows similar characteristics to the block, so it can be used as non-concrete lightweight concrete.

Experimental Example 3

In order to evaluate the usability of the lightweight aggregate according to the present invention to the structural lightweight concrete, the lightweight aggregate prepared by Example 3 was manufactured as shown in Table 7 to carry out the unit volume weight and compressive strength test The results are shown in Table 7.

In Table 7, W / C represents the weight ratio of the mixed water (W) to cement (C), S represents fine aggregate (steel sand, specific gravity 2.56, assembly rate 2.57), G is light aggregate (specific gravity 1.15, assembly rate 5.6 ), The largest dimension was used. As shown in Table 7, concrete incorporating lightweight aggregate according to the present invention has a unit volume weight of about 2,000 kg / m 3 or less, which falls within the range of structural lightweight concrete, and has excellent strength at 7 days and 28 days of compressive strength. Expression was confirmed. Therefore, it can be seen that the lightweight aggregate according to the present invention can be applied to the structural lightweight concrete.

According to the present invention, since the ignition loss due to organic sludge and unburned carbon, which have been treated indiscriminately by landfill and ocean dumping, has a low specific gravity, high added value with excellent absorption characteristics and strength characteristics using fly ash having a very low utilization rate Light weight aggregate can be produced. In particular, by sintering and partially melt-fixing various harmful substances, there is an effect that is environmentally friendly and economical recycling of organic sludge.

In addition, the use of inorganic waste such as clay, stone dust sludge, waste tailings and waste gypsum as a subsidiary material significantly reduces the production cost of lightweight aggregate.

In addition, since the waste gypsum is contained as a foaming agent in the composition for lightweight aggregate, foaming is active and physical properties are good.

In addition, by performing the foaming firing at a temperature of 1,180 ~ 1,300 ℃ for 5 to 15 minutes, sufficient sintering and foaming occurs, thereby lowering the absorption and specific gravity of the aggregate.

In addition, by forming a molded body with a composition composed of the above materials, and by coating the waste gypsum on the surface of the molded body, it is possible to prevent the moldings from sticking to each other or fusion at the time of firing to ensure completeness in the production of aggregate.

In addition, it is possible to prevent the oxide film is formed on the outside of the aggregate by increasing the temperature increase rate relatively fast, which is advantageous in weight reduction, and can continuously link the manufacturing process by controlling the cooling rate.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the technical scope of the present invention, and such modifications and modifications belong to the appended claims.

Claims (8)

10 to 20% by weight of the loss of ignition by unburned carbon as the main caking agent based on 100 parts by weight of organic sludges of one kind or two or more kinds selected from the group consisting of sewage sludge, purified sludge, dyed sludge, sugar sludge and leather sludge. Light aggregate composition comprising 4 to 100 parts by weight of fly ash and 2 to 20 parts by weight of auxiliary binder. The method of claim 1, The light weight aggregate composition, characterized in that 0.1 to 8 parts by weight of waste gypsum is further included with respect to the dry weight of the composition. The method of claim 1, The auxiliary aggregate is light weight aggregate composition, characterized in that one or two or more selected from clay, waste tailings and stone sludge. A paste manufacturing step of homogeneously mixing and drying the composition according to any one of claims 1 to 3 to prepare a paste having a water content of 20 to 40% by weight; A molded article manufacturing step of manufacturing a molded article having a predetermined shape with the paste; A molded article drying step of drying the molded article at a water content of 20% by weight or less; A foam firing step of preparing the aggregate by foaming the molded body in a kiln and foaming at a temperature of 1,180 to 1,300 ° C .; And Cooling step of cooling the aggregate; Light aggregate production method characterized in that it comprises a. The method of claim 4, wherein The manufacturing method is the lightweight aggregate manufacturing method, characterized in that before or after the molded body drying step, coating the molded body with waste gypsum. The method of claim 4, wherein The molded article manufacturing step, Forming a rectangular or columnar primary molded body by extrusion molding the paste, and putting the primary molded body into a rotating drum to coat with waste gypsum and simultaneously producing a spherical secondary molded body. The lightweight aggregate manufacturing method. The method of claim 4, wherein The foam firing step, The pre-heating portion 600 ℃ to a temperature increase to 10 ~ 30 ℃ / min, and the temperature rises from 600 ℃ the temperature zone portion to the temperature to start foaming, the lightweight aggregate production method characterized in that the temperature is made to 30 ~ 100 ℃ / min. The method of claim 4, wherein The cooling step, The lightweight aggregate manufacturing method characterized in that for cooling the aggregate at a cooling rate of 50 ~ 200 ℃ / min at a temperature of 200 ~ 300 ℃.