JPH0442848A - Production of inorganic board - Google Patents

Abstract

PURPOSE:To efficiently utilize burnt ash generating in a fluidized combustion furnace as a production raw material of an inorganic board material by molding a cement-mixed composition containing quartz sand and ash in fluidized bed to a board-like in the presence of water and hardening by curing. CONSTITUTION:In a cement mixture in which a mixing ratio of quartz sand as a silica source and cement is about 1:1 and the necessary adding materials such as a reinforcing fiber and a light weight aggregate are added, 5-50wt.% of said quartz sand is substituted with ash in a fluidized bed. Said cement-mixed composition is molded to a board-like in the presence of water and hardened by curing to afford the objective inorganic board. A substituted amount of said ash in a fluidized bed is set as 5-50wt.% of mixing amount of quartz sand because, in a case of <=5wt.%, reaction by quartz sand becomes more stronger and hardness of a product is higher, then the improving effect on workability becomes insufficient. On the other hand, in a case of >=50wt.%, degree of strength impartment by the silica source becomes lower and necessary strength as a building material is not obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing an inorganic board, and more particularly to a method for manufacturing an inorganic board 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.

In addition, various means have been disclosed for producing inorganic board materials by using fly ash, which is fine particles of ash contained in the waste gas of pulverized coal-fired boilers, as a silica source (for example, Japanese Patent Laid-Open No. 59-92956 Publication No. 59-9295
Publication No. 7).

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

The ash obtained by this fluidized bed combustion has a lower amount of coking coal than the above-mentioned fly ash, a larger specific surface area, and higher reactivity, so it can be used as a silica source for inorganic products, making it an effective use of industrial waste. It is becoming widespread for this purpose.

[Problems with conventional technology]

However, since the above fluidized bed ash has a low combustion temperature, it contains a large amount of unresolved carbon (15-20%, normal fly ash is 5% or less) and has a relatively low SiO* content, so S i required for curing reaction
Ox content tends to be insufficient, and since limestone is used as a desulfurizing agent, the ash contains a considerable amount of gypsum, which causes deterioration of the water resistance and strength of the molded product. The amount of CaCO5 contained is more than five times the reaction equivalent with sulfur in coal, so the ash after combustion contains a large amount of quicklime (Cab), which is not consumed in the cement hardening reaction and is formed into cement. Ca0 in the body
If it remains in the O-form, there is a problem of pop-out phenomenon and expansion failure due to digestive reactions during the curing process, and when considering the characteristics such as the strength of the product, it is difficult to actively use the fluidized bed method. Ta.

Further, the method of using fly ash as a silica source also has the problem that sufficient strength of the product cannot be obtained, although it is not as severe as the above-mentioned problem.

On the other hand, products using only natural silica stone as a silica source are harder than those using the fluidized bed method or fly ash described above, but have poor workability such as nailing and cutting properties, making them difficult to mix as building materials. There were points that needed improvement.

[Invention tries to solve it! l[B]

In view of the above-mentioned problems, the present invention has been made with the object of providing a method for manufacturing an inorganic board that can effectively utilize combustion ash produced in a fluidized bed combustion furnace, particularly as a raw material for manufacturing inorganic board materials.

[Technology to solve problems]

That is, the method for manufacturing the IR-free board of the present invention is a conventional method in which the mixing ratio of silica sand and cement as a silica source is approximately 1:1, and necessary additives such as reinforcing fibers and lightweight aggregate are added. 5 to 50% by weight of the above silica sand in the cement formulation according to
is replaced by a fluidized bed method, and the cement composition is formed into a plate shape in the presence of water and cured.

C Effect] As described above, a mixture of combustion ash discharged in large quantities from a fluidized bed combustion furnace and natural or waste silica sand is used as the silica source for the cement mixture used in this invention.

The fluidized bed method is S ioz -A j! Js, Fe
z03, CaO is the main component.

S +0. contained in the fluidized bed method. is consumed in the hardening reaction of cement, but CaO is not consumed in the hardening reaction and remains as it is.

Further, calcium oxide (Cab) remaining without being consumed in the cement hardening reaction gradually absorbs water and changes into calcium hydroxide (CaOHt).

This calcium hydroxide becomes Ca'' in the presence of water and forms a calcium-silicate compound in the matrix. This calcium-silicate compound is an extremely stable compound and does not undergo changes.

Therefore, the growth of microcranks generated in the cement matrix is prevented by the cement compound, contributing to improved toughness, and at the same time, the pump-amp phenomenon and expansion failure phenomenon can be prevented.

As a result, when water is added to a mixture of cement, silica sand, and a fluidized bed method to cause a hardening reaction, it is possible to impart appropriate toughness in addition to the hardness imparted by silica sand.

For this reason, as the amount of replacement of silica sand in the fluidized bed method is increased, the hardness of the product decreases and workability such as nailing performance and cutting performance improves.

In this invention, the replacement amount in the fluidized bed method is 5% of the blended amount of silica sand.
~50% by weight is used because if it is less than 5% by weight, the reaction with silica sand will be stronger, resulting in higher product hardness and poor workability improvement effect, and if it is more than 50%, the degree of strength imparted by the silica source will be low. This is because the strength required as a building material cannot be obtained. Note that this substitution rate is preferably in the range of 10 to 40% by weight of the silica sand to be added.

In addition, in order to prevent the pump-out phenomenon or expansion failure due to digestion of quicklime contained in the fluidized bed ash, the fluidized bed method may be prehydrated and used.

Note that the other cement pulp, pearlite extrusion aid, etc. are the same as the conventionally known formulations.

〔Example〕

Next, the present invention will be explained in detail.

As a fluidized bed method, a test plate with a thickness of 5 m, a length of 1 m, and a width of 451 cm was molded with the composition shown in Table 2 using the ingredients shown in Table 1 at a pressure of 8 kg/-, and after autoclave curing, the bending strength was measured. (kg/c+J) Absolute dry specific gravity (g/mouth 3) and nailing limit pass rate (20x20m) were tested and the results were shown in Table 2.
The result was

Nailing limit: As is clear from Table 2, where a nail is manually driven into the length shown in the table from the corner of the test piece and the cracks and chips that occur are visually checked, the limits of this invention are In the case of the examples, the passing rate of the nail driving limit test is almost 100χ, whereas the one that does not include the fluidized bed method shows an extremely low value of 40%.On the other hand, in terms of strength, contrary to the above, the fluidized bed method is used in large quantities It was found that the strength was significantly lacking.

[Effects] As explained above, this invention enables the effective use of the fluidized bed method, which discharges a large amount, and improves workability such as nailing and cutting properties of the product without impairing product strength. is,
This has the effect of making it possible to mass-produce products with excellent properties as building materials.

Claims (1)

[Claims] (1) When mixing cement using a conventional method in which the mixing ratio of silica sand as a silica source and cement is approximately 1:1, and necessary additives such as reinforcing fibers and lightweight aggregates are added, A method for producing an inorganic board, which comprises replacing 50% by weight with fluidized bed ash, forming the cement composition into a board in the presence of water, and curing and hardening.