JP2575963B2 - Manufacturing method of hydraulic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a hydraulic material from coal ash.

[0002]

2. Description of the Related Art Cement is a typical hydraulic material, and its production method is to burn and burn clay and limestone together with fuel in a kiln, and to pulverize and granulate the burned product into a product. ing.

[0003]

Generally, cement is fired mainly with silicon oxide (SiO ₂ ), calcium oxide (CaO), alumina oxide (Al ₂ O ₃ ) or the like to obtain C ₃ S, β-C ₂ S, C ₂ A (C: CaO, S:
SiO ₂ , A: Al ₂ O ₃ )
Fine particles of about 5 to 20 μm are added to and mixed with water, and these components react with hydroxyl groups to produce a pozzolan product to form a cured product. Various cements have been produced with these component ratios, but little attention has been paid to the product particle size or crystal form. However, in recent years, from the viewpoint of improving the performance of concrete, refinement of products and orientation of amorphous forms have been studied.

[0004] On the other hand, coal ash contains a large amount of SiO ₂ and Al ₂ O ₃ which are constituents of cement, and also contains a small amount of CaO in a small amount, and contains a component usable as a hydraulic material. .

The present invention has been made in view of the above points, and effectively utilizes coal ash generated in large quantities from coal-fired boilers and the like and discarded as industrial waste, and has good hydraulicity. It is intended to provide a method for producing a hard material.

[0006]

As a means for solving the above-mentioned problems, the method for producing a hydraulic material of the present invention employs the following means.

(1) Coal ash composed of mineral substances such as silicon oxide (SiO ₂ ) and alumina oxide (Al ₂ O ₃ ) is burned with oxygen or oxygen-enriched air as a fuel. fed into the combustion furnace to form a selectively vaporize the SiO ₂ which is a low boiling substance in the coal ash.

(2) Combustion at the outlet of the combustion furnace
Evaporated SiO contained in the firing gas _TwoCooling and condensing steam
And SiO_TwoIt produces solid ultrafine particles rich in components.

(3) Fine particles of calcium oxide (CaO) or calcium carbonate (CaCO ₃ ) (for example, fine particles of limestone) are supplied to the outlet of the combustion furnace, mixed with high-temperature exhaust gas discharged from the combustion furnace, and subjected to mixing. SiO ₂ and Al ₂ O
₃ , to produce fine particles of SiO or composite crystals thereof.

(4) The fine particles are cooled and collected to obtain hydraulic fine particles.

[0011]

[Operation] The operation in each step described in the previous section is as follows.

In the step (1), a part of the SiO _{2 in} the coal ash is vaporized, and the coal ash is leached and scattered after the vaporization. The amount of the vaporized SiO _{2 and} the amount of the scattered fine particles from the coal ash are provided. Is controlled. This is adjusted by the shape of the combustion furnace, the burner arrangement, the amount of combustion, and the like.

[0013] (2) At the stage of ~ (3), cooling the SiO ₂ steam discharged from the combustion furnace by the cooling gas SiO ₂
Generates a 0.1μ following ultrafine particles-rich component, a mixture of CaO or CaCO ₃ particulate into the hot flue gas of the combustion furnace outlet Te併Align, SiO ₂ of the fine particles of the CaO or CaCO ₃ reacting the scattering particles from fine particles and coal ash rich component, component to SiO _2, Al ₂ O
₃ , to produce fine particles of SiO ₂ or composite crystals thereof.

In the step (4), the above-mentioned fine particle material is cooled to change its crystal form, and the ultra-fine particle material is cooled and collected. In this stage, the crystal form of the reaction product is changed by changing the cooling rate of the ultrafine particle material as the reaction product by means such as adjusting the amount of cooling gas input. For example, if the cooling rate is low,
The reaction product becomes a crystalline product. Conversely, when the cooling rate is high, an amorphous type product is obtained. The case where the cooling rate is low is 100 ° C / min to 500 ° C / min, and the case where the cooling rate is high is 100 ° C / sec to 500 ° C / min.
sec.

[0015]

FIG. 1 shows a system of a method for producing a hydraulic material according to one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a combustion furnace which is constituted by a cooling wall and burns fuel with oxygen or oxygen-enriched air to form a high-temperature combustion field of 2400 ° C. or higher, 2 denotes a flue gas downstream of the combustion furnace, 3
Is a coal ash feeder, 4 is a CaO-containing mineral feeder, 5
Is a coarse dust collector, 6 is a precision dust collector, 7 is molten slag flowing down from the combustion furnace 2, 8 is a slag tank, 9 is a hydraulic material collected by the coarse dust collector 5 and the precision dust collector 6. , 10 indicate molten slag flowing down the combustion furnace wall.

In FIG. 1, a thin solid line represents a cooling water system for combustion, a thick solid line represents a fuel system, a thin dashed line represents a coal ash supply system, a thin two-dot chain line represents an oxygen or enriched oxygen supply system, and a thick dashed line represents a CaO-containing mineral. The quality supply system and the bold broken lines indicate the respective systems of the cooling gas supply system.

The fuel supplied to the combustion furnace 1 is a solid fuel such as coal, a gaseous fuel, or a liquid fuel. The fuel system and the oxygen or oxygen-enriched air supply system are composed of a plurality of systems. The cooling gas may be an inert gas such as water vapor or nitrogen, in addition to air, and the cooling gas is introduced stepwise from several places in the flue 2 after the combustion furnace.

In FIG. 1, coal ash is supplied to a coal ash supply device 3.
2400 ° C in the combustion furnace 1
It is supplied to the above high-temperature combustion field. The supplied coal ash is melted in the high-temperature combustion field, one part of the SiO ₂ in the molten coal ash is vaporized, and the remainder is captured by the cooling furnace wall as molten slag 10 as molten slag out of the downstream combustion furnace system as a discharged slag tank. It is discharged to 8.

On the other hand, the combustion gas containing the vaporized SiO ₂ vapor and the fine particle molten ash that has flew out of the coal ash is exhausted from the upper part of the combustion furnace 1 to the flue 2 downstream of the combustion furnace, and introduced into the flue 2. The cooling gas is sequentially cooled at a cooling rate of about 200 ° C./sec. At the cooling stage, the SiO ₂ vapor condenses to solid ultrafine particles of 0.1 μ or less, and the fine particle molten ash cools and solidifies. It becomes fine particles of several μ or less. In this process, SiO
_{(2) The} vapor changes its phase from a gas phase to a liquid phase to a solid phase, and the particulate ash changes its phase to a liquid phase to a solid phase.

In this cooling gas introduction process, the CaO-containing mineral matter atomized to several μm is supplied from the supply device 4 to the downstream flue 2 of the outlet of the combustion furnace 1 by a carrier gas. This carrier gas may be used together with the cooling gas.

The supplied CaO-containing mineral substance (eg, limestone) is mixed into the high-temperature exhaust gas, and SiO ₂ in the gaseous phase, liquid phase, or solid phase present in the high-temperature exhaust gas, and the liquid phase, solid state mixed with fine molten ash in the SiO _2, a
A particulate reaction product of l ₂ O _{3 and the} like with CaO is generated. This particulate reactant has on average the same size as the several μm of CaO-containing mineral supplied.

The reaction product is further cooled by a cooling gas, and by setting this cooling rate appropriately, a hydraulic material having a different crystal form of the reaction product is produced.

In general, it can be made amorphous by increasing the cooling rate, and can be made crystalline by slow cooling. The ratio of each component of the hydraulic material can be arbitrarily adjusted by changing the supply amount of the CaO-containing mineral substance.

The reaction product of the ultra-fine particles cooled as described above is collected by the coarse dust collector 5 and the fine dust collector 6,
An ultrafine hydraulic material 9 is obtained.

[0026]

The method for producing a hydraulic material according to the present invention has the following effects.

(1) Coal ash discarded as industrial waste can be effectively used.

(2) Coal ash is treated in a high temperature field and then cooled to form ultrafine SiO ₂ particles of 0.1 μm or less and several μm.
The following fine particles are obtained.

Further, since the fine particles of CaO or CaCO ₃ are supplied, the reaction product synthesized as a result (ie,
The hydraulic material) is a fine particle reaction product having the same size as the fine particles of CaO or CaCO _{3 on} average. CaO or C
It is easy to pulverize aCO ₃ to several μm. In this case, a few μm fine particle reaction product is generated on average, which is one order of magnitude smaller than that of conventional cement. When used as an active ingredient, it has the effect of activating the reactivity.

(3) The crystal form of the reaction product can be changed by adjusting the cooling rate with a cooling gas. In particular, by increasing the cooling rate, an amorphous form can be obtained, so that when it is also used as concrete, the reactivity can be activated.

[Brief description of the drawings]

FIG. 1 is a system diagram of one embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 combustion furnace 2 wake flue 3 coal ash supply device 4 CaO-containing mineral substance supply device 5 coarse dust collector 6 precision dust collector 7 molten slag 8 slag tank 9 hydraulic material 10 molten slag

Claims (1)

(57) [Claims] 1. A coal ash composed of a mineral substance such as silicon oxide or alumina oxide is supplied to a combustion furnace which forms a high-temperature combustion field of 2,400 ° C. or higher by burning fuel with oxygen or oxygen-rich air, Silicon oxide, which is a low-boiling substance in the coal ash, is selectively vaporized, and the vaporized vapor is cooled and condensed with a cooling gas at a combustion furnace outlet to produce solid ultrafine particles rich in silicon oxide components, and the combustion furnace Fine particles of calcium oxide or calcium carbonate are supplied to the outlet portion and mixed with high-temperature exhaust gas at the outlet portion to form silicon oxide, alumina oxide, calcium oxide, or fine particles of these composite crystals as components, A method for producing a hydraulic material, wherein the particulate matter is cooled and collected.