JP2001302292A - Method of producing hydraulic calcium silicate raw material by utilizing used alc panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a raw material of hydraulic calcium silicate by utilizing used ALC panels generated from the house-wrecking sites thereby contributing to the reduction of industrial waste and saving the exhausting natural resources as the substitute of cement. SOLUTION: The objective process comprises the crushing step where used ALC panels recovered from the house-wrecking sites are crushed into ALC pieces, the separation step where the metals, for example, the reinforcing steel and the like are separated from the resultant ALC pieces, the heating step where the ALC pieces after the separation of the metals are treated with high temperature at 800-1,100 deg.C by utilizing the waste heat from the waste combustion and the fine grinding step where the ALC pieces are finely crushed before or after the high-temperature treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for effectively utilizing a used ALC panel generated from a demolition site of a building,
The present invention relates to a method for producing a hydraulic calcium silicate-based raw material, which is a part of a raw material such as cement.

[0002]

2. Description of the Related Art In general, ALC (lightweight cellular concrete) is mainly composed of natural silica stone or light sand as a siliceous raw material and limestone or cement directly produced from a natural raw material as a calcareous raw material. It is obtained by foam curing and then steam curing.

[0003] In other words, in addition to gypsum as a secondary raw material, a repetitive raw material such as ALC cutting waste before autoclave curing is added to the above-mentioned main raw material, water is added to the mixture to form a mixed slurry, and aluminum is added thereto. A foaming agent such as a powder is added, and a reinforcing reinforcing bar to be incorporated into the ALC panel is injected into a mold in which the reinforcing bar is previously incorporated, and is cured simultaneously with foaming. Further, when a plastic state is obtained after a lapse of a predetermined time, the piece is cut into a predetermined size with a piano wire, and then placed in an autoclave and subjected to steam curing at high temperature and high pressure.

[0004] The obtained ALC is cut into a predetermined size to be a building material such as a panel. ALC panels as building materials are widely used as materials for outer walls, roofs, floors and the like of buildings such as reinforced concrete and RC.

[0005] From the ALC manufacturing process in this factory,
ALC waste such as cutting chips or cutting chips generated due to dimensional adjustment, or defective products due to breakage or the like is generated. Almost all of the in-plant waste generated in the ALC manufacturing plant is repeatedly reused as a raw material in the ALC manufacturing process. As a method thereof, it is common practice to repeatedly use the pulverized waste material in the factory as it is without performing any heat treatment.

[0006]

[PROBLEMS TO BE SOLVED BY THE INVENTION] Used AL generated from a building demolition site due to rebuilding or demolishing of a building
The number of C panels has been increasing especially since 30 years or more have passed since the start of production of ALC in Japan, and is much larger than the above-mentioned factory waste.

However, such used ALC panels generated in large quantities are partially crushed or crushed and used for roadbed materials and landfill works, but most of the used ALC panels are recycled. They were dumped at the disposal site as industrial waste without being used.

The present invention has been made in view of such a conventional situation,
The purpose of the present invention is to provide a new method of manufacturing hydraulic calcium silicate-based raw materials by using used ALC panels generated from the demolition site of buildings, thereby contributing to the reduction of industrial waste and the reduction of cement waste. The aim is to save resources of natural raw materials that are being depleted as substitutes.

[0009]

In order to achieve the above object, the present invention provides a method for producing a hydraulic calcium silicate-based raw material using a used ALC panel recovered from a building demolition site. That is, the method for producing a hydraulic calcium silicate-based raw material of the present invention comprises a crushing step of roughly pulverizing the used ALC panel into ALC pieces,
A separating step of separating the metal from the C pieces, a heating step of subjecting the ALC pieces after the metal separation to a high temperature treatment, and a pulverizing step of pulverizing the ALC pieces before or after the heating step. It is a feature.

The method for producing a hydraulic calcium silicate-based raw material according to the present invention is characterized in that in the separating step, the reinforcing bar and the mounting bracket are separated from the ALC pieces by a magnetic separator. In the method for producing a hydraulic calcium silicate-based raw material according to the present invention, in the heating step, the temperature of the high temperature heat treatment of the ALC piece is set to 800 to 1100 ° C.

Further, as a high-temperature heating device used in the heating step, a rotary kiln or a fluidized-bed furnace can be used. In addition, as a heat source of these high-temperature heating devices,
It is preferable to use waste heat generated by incineration of waste.

[0012]

The main hydraulic components of the embodiment of the invention] ALC is tobermorite produced by performing the high-temperature high-pressure steam curing in an autoclave (5CaO _· 6SiO 2 · 5H
And crystalline calcium silicate hydrate called _{2 O),}
It consists of unreacted silica. This tobermorite is
It reacts with carbon dioxide gas in the air in the presence of moisture to be carbonated, and is decomposed into calcium carbonate (CaCO ₃ ) and silica gel.

The rate at which tobermorite is carbonated in the ALC depends not only on the carbon dioxide concentration but also on the relative humidity,
It is affected by temperature, ALC water content, ALC surface treatment condition (type of coating, thickness, repair), etc., and therefore varies in the same building or in the same ALC panel. However, since ALC after construction on a building always has a surface in contact with air containing carbon dioxide, at least a part of tobermorite in used ALC is always carbonated.

It is known that tobermorite which has not been subjected to carbonation, for example, tobermorite in ALC which is waste material from a factory, is turned into wollastonite and zonolite when heated to 800 ° C. or higher (Japanese Patent Application Laid-Open No. H5-105). However, when used ALC is calcined at 800 ° C. or more, it is found that wollastonite produced has low crystallinity and generates an unstable substance whose crystal structure does not completely match. Was. This suggests that the partially carbonated tobermorite has changed its structure as described above, and that the carbonated tobermorite has a temperature of 800 ° C.
The minerals generated by decomposition as described above are unstable, in other words, easily reactable.

That is, the used ALC partially carbonated with tobermorite is heated and calcined at 800 ° C. or more, and together with unreacted siliceous materials such as silica stone, chemically unreacted tobermorite, in which a part of tobermorite is decomposed by heating. A novel calcium silicate-based raw material containing a stable calcium silicate-based mineral is obtained.

This calcium silicate-based raw material reacts with water, hydrates a chemically unstable calcium silicate-based mineral having low crystallinity, and hardens by forming calcium silicate-based hydrate. have. In other words, the calcium silicate-based raw material provided by the present invention has hydraulic properties similar to commonly used cement, and can be used instead of a part of cement.

Next, a method for producing a hydraulic calcium silicate-based raw material using a used ALC panel will be described.
ALC as a raw material is used ALC panels generated from buildings such as demolished buildings and houses. The disassembled ALC panel usually exists in the form of a plate having a width of 60 cm or less and a length of 6 m or less, or a block of several cm to several tens cm. Furthermore, since it is mainly used as an outer wall material, a reinforcing reinforcing bar is arranged inside the ALC panel, and the surface and side surfaces are coated or sealed to ensure waterproofness.

In the crushing step, these used ALC panels are first roughly crushed to a size of several mm to several cm using a crushing device such as a hydraulic press. In the next separation step, metals such as reinforcing steel bars embedded in the panel and metal fittings for mounting the panel are separated and collected from the ALC pieces obtained in the crushing step by hand or by a magnetic separator. A after the metal is separated and removed by the separation step
The LC piece is subjected to a pulverizing step after the heating step, or a heating step after the pulverizing step in the reverse order to produce a hydraulic calcium silicate-based raw material.

The heating temperature of the ALC piece in the heating step needs to be 800 ° C. or higher, but is preferably 800 to 800 ° C.
The range is 1100 ° C. This is because the heating temperature is 1100
When the temperature exceeds ℃, not only the energy cost for heating increases, but also at 1500 ° C or more, the mineral particles in the ALC are melted, the specific surface area is reduced, and at the same time, a highly crystalline calcium silicate-based mineral is generated by a solid-phase reaction. This is because there is a possibility and the hydration reactivity becomes poor.

The coating and sealing adhered to the surface and side surfaces of the coarsely pulverized ALC pieces have a melting point of 600 ° C. or less, and thus are removed by the high-temperature heat treatment in the heating step at 800 ° C. or more. As a high-temperature heating device used in the heating step, a rotary kiln or a fluidized furnace can be used. Further, if high-temperature exhaust heat generated from waste incineration equipment is used as a heat source of these high-temperature heating devices, effective use of energy can be achieved, which is extremely advantageous.

In the fine pulverizing step, a coarsely pulverized ALC piece is finely pulverized to a particle size of 1 mm or less by using a fine pulverizing device such as a roller mill to have a size usable as a part of a cement raw material. . This pulverization step may be performed before or after the heating step. However, if the pulverization step is performed before the heating step, there is an advantage that the heating time in the subsequent heating step can be reduced.

As a preferred embodiment of the method of the present invention, FIG. 1 shows a process chart in which an apparatus used in a general cement production process is used as a main production apparatus. In FIG. 1, a specific device such as a rotary kiln is used as the high-temperature heating device. However, a device other than the device shown in FIG. 1 can be used.

According to the preferred method according to the process diagram of FIG. 1, first, the used AL
The C panel (carbonated) is collected and coarsely pulverized using a crusher such as a hydraulic press. Since a reinforcing bar is previously installed inside the ALC panel, metals such as the reinforcing bar and the metal fittings are separated and removed using a magnetic separator, and are reused or provided for other recycling.

The ALC pieces roughly crushed from several mm to several cm by the crushing device are put into a loading hopper by a transport device such as a conveyor, and then 800 to 11 mm by a rotary kiln.
Heat treatment is performed at a high temperature of 00 ° C. The processing time by high-temperature heating may be several minutes to about 30 minutes, but the heating time can be shortened by performing pulverization in advance before putting into a high-temperature heating device.

As a heat source of the rotary kiln, which is a heating device, fossil fuel may be used, but energy costs can be reduced by utilizing waste heat generated during waste treatment. As a method of utilizing the exhaust heat, the exhaust heat of the incinerator (gasification and melting furnace outlet temperature: about 1400 ° C.) may be recovered by a heat exchanger or the like, and the high-temperature exhaust gas may be directly passed through a rotary kiln. In this case, an auxiliary heating device using fossil fuel is provided, and the temperature of the heating device such as a rotary kiln is set to 800.
When the temperature falls below ℃, the temperature may be increased by an auxiliary heating device.
Exhaust gas from the rotary kiln is released to the atmosphere after dust removal by a bag filter.

The ALC piece thus heat-treated at a high temperature is put into a fine pulverizing device such as a roller mill, and 1 mm
It is pulverized to the following particle size to obtain a calcium silicate-based raw material. Since the obtained calcium silicate-based raw material has hydraulic properties by itself, it can be used in a mixture with ordinary Portland cement or the like to reduce the amount of cement used. In addition, by using it as a ground improvement material, it can be expected that the ground strength will increase due to its hydraulic property compared to a case where the ALC waste material is simply buried and used.

[0027]

According to the present invention, a hydraulic calcium silicate-based material that can be used as a substitute material for cement can be manufactured by reusing a used ALC panel generated from a building demolition site. In addition, the reuse of ALC panels, which were previously disposed of as waste, not only contributes to the reduction of industrial waste, but also enables the production of hydraulic calcium silicate-based raw materials to be used as cement raw materials. It is also effective in conserving natural resources that are becoming more resource-saving.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing a specific production process of a hydraulic calcium silicate-based raw material according to the method of the present invention.

Claims (6)

[Claims] 1. A method for producing a hydraulic calcium silicate-based raw material using a used ALC panel collected from a building demolition site, wherein the used ALC panel is roughly pulverized into ALC pieces. And a separation step of separating a metal from the obtained ALC piece, and an AL after separating the metal.
A method for producing a hydraulic calcium silicate-based raw material, comprising: a heating step of treating a C piece at a high temperature; and a pulverizing step of pulverizing an ALC piece before or after the heating step. 2. The method for producing a hydraulic calcium silicate-based raw material according to claim 1, wherein in the separation step, the reinforcing reinforcing bar and the mounting bracket are separated from the ALC pieces by a magnetic separator. 3. The method for producing a hydraulic calcium silicate-based raw material according to claim 1, wherein in the heating step, the temperature of the high-temperature heat treatment of the ALC piece is set to 800 to 1100 ° C. 4. The method for producing a hydraulic calcium silicate-based raw material according to claim 1, wherein in the heating step, a rotary kiln is used as a high-temperature heating device. 5. The heating process according to claim 1, wherein a fluidized-bed furnace is used as a high-temperature heating device.
The method for producing a hydraulic calcium silicate-based raw material according to any one of the above. 6. The hydraulic calcium silicate according to claim 1, wherein in the heating step, waste heat generated by incineration of waste is used as a heat source for high-temperature heat treatment. Production method for raw materials.