JP2521562B2 - Method for manufacturing inorganic plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an inorganic plate, and more particularly to a method for producing an inorganic plate using combustion ash produced in a fluidized bed combustion furnace.

[Conventional technology]

Conventionally, natural silica sand or waste silica sand generated during the production of glass products has been widely used as a silica source.

Besides, various means for producing an inorganic plate material have been disclosed by using fly ash, which is fine powder particles of ash contained in the waste gas of a pulverized coal combustion boiler, as a silica source (for example, JP-A-59-92956). No. 59-92957).

By the way, as a combustion furnace, a fluidized bed combustion furnace is known in addition to the above-described high temperature combustion furnace.

The ash obtained by this fluidized bed combustion has a lower caking degree than the above-mentioned fly ash, a large specific surface area, and high reactivity, so it can be used as a silica source for inorganic products, and effective use of industrial waste It is spreading widely for the purpose.

[Problems of conventional technology]

However, since the fluidized bed ash has a low combustion temperature, it contains a large amount of carbon (15 to 20% or less than 5% in normal fly ash), and the SiO ₂ content is relatively low, so that the cement matrix is hardened. The amount of SiO ₂ required for the reaction tends to be insufficient, and since limestone is used as a desulfurizing agent, a fairly large amount of gypsum is contained in the ash, which becomes a factor that deteriorates the water resistance and strength of the molded body, and desulfurization. The amount of CaCO ₃ contained in the limestone used as an agent is more than 5 times the reaction equivalent of sulfur in the coal, so the ash after combustion contains a large amount of quicklime (CaO), which is the hardening reaction of cement. If it is not consumed but remains in the form of CaO in the molded body, there is a problem that it causes a pop-out phenomenon and expansion failure due to a digestion reaction during the curing process. Considering characteristics such as strength of the product, use of fluidized bed ash Is aggressive There has been difficult to adopt a problem.

Further, the method of using fly ash as a silica source has a problem that the product strength cannot be sufficiently obtained as a problem of a degree to a lesser degree.

On the other hand, a product using only natural silica as a silica source has hardness as compared with the use of the above fluidized bed ash or fly ash, but the workability such as nailability and cutting property is poor, and it is not suitable for compounding as a building material. There was a point to be improved.

[Problems to be Solved by the Invention]

The present invention has been made in view of the above problems, and an object thereof is to obtain a method for producing an inorganic plate that can be effectively used as combustion raw material produced from a fluidized bed combustion furnace, particularly as a raw material for producing an inorganic plate material.

[Technology for solving problems]

That is, the method for producing an inorganic plate of the present invention is a cement mixture by a conventional method in which the mixing ratio of silica sand as a silica source and cement is approximately 1: 1 and pulp fibers as reinforcing fibers and pearlite as lightweight aggregate are added thereto. In the above method, 5 to 50% by weight of the silica sand is replaced with fluidized bed ash, the cement composition is molded into a plate in the presence of water, and autoclaved for curing.

[Action]

As described above, a mixture of combustion ash and natural or waste silica sand, which is discharged in a large amount from the fluidized bed combustion furnace, is used as the silica source of the cement mixture used in the present invention.

Fluidized bed ash has SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , and CaO as the main components.

The SiO ₂ contained in the fluidized bed ash consumes the hardening reaction of cement, but the CaO remains as it is without being consumed in the hardening reaction.

Calcium oxide (CaO) remaining without being consumed in the hardening reaction of cement gradually absorbs water and changes to calcium hydroxide (CaOH ₂ ).

This calcium hydroxide becomes Ca ^{++ in} the presence of water to form a calcium-silicate compound in the matrix. This calcium-silicate compound is a very stable compound and does not change.

Therefore, the microcracks generated in the cement matrix are prevented from developing by this compound and contribute to the improvement of toughness, and at the same time, the pop-up phenomenon and the expansion fracture phenomenon can be prevented.

As a result, when water is added to the mixture of cement, silica sand, and fluidized bed ash to cause a hardening reaction, it is possible to impart a suitable toughness together with the hardness imparted by the silica sand.

Therefore, as the replacement amount of the fluidized bed ash for silica sand is increased, the hardness of the product is reduced and the workability such as nailability and cutting property is improved.

In the present invention, the substitution amount of fluid bed ash is set to 5 to 50% by weight of the content of silica sand. When the amount is less than 5% by weight, the reaction by silica sand becomes stronger, resulting in higher product hardness and poor workability and hardening. If it is more than 50%, the degree of strength imparted by the silica source becomes low, and the strength required as a building material cannot be obtained. This substitution rate is
A range of 10-40% by weight is preferred.

The fluidized bed ash may be pre-hydrated and used in order to prevent a pop-out phenomenon or expansion destruction due to digestion of quicklime contained in the fluidized bed ash.

The other cement pulp, pearlite extrusion aid and the like are the same as those conventionally known.

〔Example〕

 Next, an embodiment of the present invention will be described.

Using a fluidized bed ash with the content of components shown in Table 1, press the test plate with a thickness of 15 mm, a length of 1 m and a width of 45 cm with the composition of Table 2.
Extrusion molding at 8 kg / cm ² and curing in an autoclave, bending strength (kg / cm ² ), absolute dry specific gravity (g / cm ³ ), and nailing limit pass rate (2
When the test of 0 × 20 mm) was performed, the results shown in Table 2 were obtained.

As is clear from Table 2, in the case of the examples of the present invention, the passing rate of the nailing limit test is almost 100%, whereas the one not containing the fluidized bed ash shows an extremely low value of 40%, while the strength Contrary to the above, it was found that those containing a large amount of fluidized bed ash had a markedly insufficient strength.

[Effect] As described above, the present invention enables effective use of fluidized bed ash discharged in a large amount, and the nailability of the product,
The workability such as cuttability is improved without impairing the product strength, and it is possible to mass-produce products having excellent properties as a building material.

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Claims (1)

(57) [Claims] 1. A silica compound as a silica source and cement having a mixing ratio of about 1: 1 and pulp fibers as reinforcing fibers and pearlite as a lightweight aggregate are added thereto in a conventional cement compounding method to obtain 5 parts of the above-mentioned silica sand. A method for producing an inorganic plate, characterized in that -50% by weight is replaced with fluidized bed ash, the cement composition is molded into a plate in the presence of water, and autoclaved.