JP2002187747A - Cement clinker and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cement clinker which enables improvement in reduction rate of cement compressive strength and increase in blending ratio of waste in a clinker raw material blend, and also to provide a cement composition. SOLUTION: This cement clinker is obtained by firing a raw material blend containing phosphorous-containing waste (such as sewage sludge and municipal solid waste incineration ash) and has a 0.3-5.0 mass% P2O5 content, a hydraulic modulus(HM) of 2.16-2.40 and a silica modulus(SM) of 1.3-2.4 (excluding 2.4). This cement composition is produced by grinding the cement clinker and gypsum and has a 1.5-3.0 mass% total SO3 content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement clinker and a cement composition, and more particularly to a cement clinker having a high P ₂ O ₅ content and a specific hydraulic and silica ratio, and a method using the clinker. The present invention relates to a cement composition in which the rate of decrease in compressive strength is improved.

[0002]

2. Description of the Related Art In recent years, industrial by-products such as incinerated ash of municipal waste, sewage sludge and its incinerated ash, and steelmaking slag (collectively referred to as "waste") have been increasing and their effective use has been increasing. Utilization has become a social urgent matter. As a countermeasure, the cement manufacturing industry is studying so-called recycling, which uses waste as part of raw materials.

However, most wastes contain a large amount of a phosphorus compound (0.3 to 30% by mass in terms of P ₂ O ₅ ). Therefore, when used as a raw material for Portland cement clinker, phosphorus It is known that some of the compounds remain in the clinker and adversely affect the properties of the cement.

[0004] In particular, the effect is remarkable on the strength development of the cement, and the greater the residual amount, the more the strength decreases. Typically, the ordinary Portland cement clinker, P ₂ O ₅ is contained 0.1 to 0.2 wt% (0.3 wt% at most).

However, when the P ₂ O ₅ content of ordinary Portland cement clinker is increased to 0.5% by mass by using waste as a raw material, the compressive strength of cement produced from the clinker (age 7 Day) to about 89%, and to about 1.0% by mass, to about 74%.

As a method of improving the decrease in the compressive strength, the inventors of the present invention focused on two components of [P ₂ O ₅ -MgO] of ordinary Portland cement produced by mixing wastes, and determined compressive strength and compressive strength. When the amount of P ₂ O ₅ in the prepared raw material is 0.3 to 2.0% by weight (calcination base), the Mg additive is reduced to 1.0 to
It has been found that it is preferable to mix the compound in the range of 5.0% by weight, and a patent application was filed (see Japanese Patent Application No. 11-81383).

[0007]

As for the quantitative relationship between P ₂ O ₅ and MgO, if the content of the former is increased by blending a large amount of waste, the latter is also blended accordingly.

However, the JIS standard for Portland cement specifies that the allowable amount of MgO is 5.0% by weight or less. Due to the quantitative limit of MgO, the content of P ₂ O ₅ was 2.0
It has been pointed out that the amount is less than 10% by weight, the amount of waste in the blended raw material (the amount of treatment) is small, and the contribution to recycling is low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional method, and has the following objects: (1) to improve the rate at which the compressive strength of cement is reduced; It is an object of the present invention to provide a "cement clinker and a cement composition thereof" which can increase the amount.

[0010]

The purpose of the cement clinker can be achieved by specifying the following one-component two ratio. That is, the cement clinker of the present invention has a P ₂ O ₅ amount, a hydraulic modulus (HM) and a silicate ratio (SM).
Is limited to a specific range, whereby the compressive strength of the cement composition produced from the cement clinker is reduced even if P ₂ O ₅ is contained in an amount larger than the upper limit of the conventional clinker. This has the effect of improving the rate at which it is performed. Accordingly, the present invention provides an increase in the amount of waste and a high-phosphorus content waste in the blended raw material, that is, an improvement in the recycling of waste, which is provided herein.

[0011] That is, first (cement clinker) of the present invention is a cement clinker obtained by firing the formulation material blended with "phosphorus-containing wastes and · P ₂ O ₅ content of 0.3 5.0% by mass, and a hydraulic modulus (HM) of 2.16 to 2.40, and a silicate ratio (SM) of 1.3 to less than 2.4 "(claim 1). Make a summary.

The first aspect of the present invention is that: the waste is at least one selected from sewage sludge, sewage sludge incineration ash, municipal waste incineration ash, and steelmaking slag (claim 2); The SiO ₂ raw material used as the raw material is coal ash (claim 3).

Further, the second (cement composition) of the present invention
Is the cement clinker described in any of the above, so that the total SO ₃ amount is 1.5 to 3.0% by mass, gypsum is mixed and pulverized, or the clinker and gypsum are individually The gist of the invention is that it is ground and mixed (Claim 4).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The first aspect of the present invention will be described. The present invention increases the upper limit of P ₂ O ₅ content in the cement clinker, a significant reduction of the resulting compressive strength on the basis thereof, two ratios (water hardness index, silica ratio) of the chemical composition by combining It is an improvement. As a result, a large amount of waste containing various phosphorus compounds can be blended into the prepared raw material as a raw material.

Although the effect of P ₂ O _{5 on} the strength reduction is great, compressive strength can be recovered (expressed) to such an extent that it can be used as a hardened cement by limiting the ratio to a specific range.

The P ₂ O ₅ content in the cement clinker is
It is 0.3 to 5.0% by mass. If it is less than 0.3% by mass, there is almost no effect on the compressive strength. It is almost the same as the case where the prepared raw material is prepared and baked using only the raw material for manufacturing cement clinker. Even if the waste is used as the raw material, the compounding amount is extremely small and the waste is recycled. , It simply complicates the manufacturing process and has no industrial advantage.

On the other hand, if it exceeds 5.0% by mass, it is not preferable to adjust the hydraulic modulus (HM) and / or the silicic acid ratio (SM) because the compression strength is greatly reduced.

Next, the two ratios of the cement clinker will be described. Hydraulic modulus (HM) is one of the important ratios that determine the chemical composition of cement, but its effect on compressive strength is small unless it is higher than that of ordinary Portland cement clinker. When the hydraulic hardness (HM) is less than 2.16, and when the content of P ₂ O ₅ is large, the reduction in compressive strength is large, which is not preferable.

On the other hand, if it exceeds 2.40, the heat of hydration of the cement is increased and its use is restricted, and the fluidity of the mortar or concrete is remarkably reduced to deteriorate the workability. However, it is not preferable because properties other than the compressive strength are adversely affected.

The hydraulic hardness (HM) is preferably in the following range in relation to the P ₂ O ₅ content. When P ₂ O ₅ is 0.3 to 3.0% by mass;
6 to 2.25 When P ₂ O ₅ is 3.0 to 5.0% by mass; hydraulic coefficient 2.2
5 to 2.40

The silicic acid ratio (SM) of the cement clinker will be described. When the silicic acid ratio is less than 1.3, the heat of hydration of the cement is increased, and the fluidity of the mortar or concrete is reduced. Absent.

On the other hand, if it exceeds 2.4, and if the content of P ₂ O ₅ is relatively large, it is not preferable because the reduction in compressive strength is large.

[P ₂ O ₅ content: hydraulic modulus: silicic acid ratio]
In view of the above, when a large amount of waste is blended to increase the P ₂ O ₅ content, it is preferable to blend the raw materials so as to have a [high hydraulic modulus / low silicic acid ratio].

The ratio of chemical components used in the production of Portland cement; iron ratio (IM)
Although not particularly limited, it is approximately 1.5 to 1.8.
Is preferable.

Next, the waste will be described. Normal,
The waste contains various phosphorus compounds, the amount of which is large as described above, and is about 30% by mass (P ₂ O ₅
Conversion) is also included.

Specific examples of the waste compounded in the raw material include sewage sludge, sewage sludge incineration ash, municipal waste incineration ash, and steelmaking slag. They may be used alone or in combination of two or more when preparing the blended raw materials.

As the raw material of the cement clinker, in addition to the above-mentioned waste, a raw material to be blended in the production of ordinary Portland cement clinker is used. For example, · CaO raw material; limestone, quicklime, etc. · SiO ₂ raw material slaked lime; silica, clay, etc. · Fe ₂ O ₃ raw material; Tetsukasu, Tetsuke - keys and the like.

In the cement clinker of the present invention, S
Coal ash containing a large amount of iO ₂ can be used instead of and / or together with the SiO ₂ raw material. The main chemical components of coal ash are SiO ₂ ; 40 to 70% by mass, Al ₂ O ₃ ;
10 to 40% by mass, Fe ₂ O ₃ ; 2 to 10% by mass and C
aO: 1 to 30% by mass.

The above coal ash is generated when coal is burned in a thermal power plant, various factories, or the like. For example, fly ash, cinder ash, bottom ash, clinker ash, and the like.

The method for producing a cement clinker of the present invention comprises:
As in the case of ordinary Portland clinker, pulverization is carried out using the above-mentioned waste and raw materials, blended and mixed so as to conform to a predetermined amount of P ₂ O ₅ , hydraulic modulus and silicic acid ratio, and mixed. It is obtained by preparing and firing. Conventional equipment such as NSP kiln and SP kiln can be used for firing. The firing temperature is preferably higher than when firing the raw material of ordinary Portland cement clinker, because the hydraulic setting of the cement clinker is high.

Next, the second (cement composition) of the present invention will be described. The cement composition is manufactured by blending gypsum with the above-mentioned cement clinker so that the total SO ₃ amount falls within the range of 1.5 to 3.0% by mass, and pulverizing the mixture. The gypsum used in the present invention is one of dihydrate / hemihydrate / anhydrite or a mixture thereof.

When the total amount of SO ₃ contained in the cement composition is less than 1.5% by mass; instantaneous setting or a decrease in fluidity occurs. When it exceeds 3.0% by mass; This is undesired in either case.

The cement composition can be obtained by carrying out any of a method of mixing and pulverizing cement clinker and gypsum, and a method of individually pulverizing and mixing.

Preferably, the pulverization is performed so that the cement composition has a Brain specific surface area of 3000 to 4500 cm ² / g. Conventional equipment can be used for the pulverizer used for pulverization.

[0035]

EXAMPLES (Examples 1 to 7 and Comparative Examples 1 to 7) Raw materials having the chemical components shown in Table 1 were pulverized and mixed to prepare a prepared raw material, which was then fired, and the ratio of one component to two as shown in Table 2 Various cement clinkers with (P ₂ O ₅ content, hydraulic modulus and silicic acid content) were produced. The iron ratio (IM) is 1.6 to 1.7.

[0036]

[Table 1]

Mixing gypsum with the cement clinker
And pulverized to obtain a total SO shown in Table 2. _ThreeEach with quantity
These cement compositions were produced. Of each cement composition
As a result of measuring the lane specific surface area, 3200 ± 50 cm^Two
/ G. The obtained cement composition is JIS R
 5201 Pressure according to “Physical test method of cement”
The shrinkage strength (age 7 days) was measured, and the results were recorded in the same table.
Was. In addition, the cement described in Comparative Example 1 was a normal Portra
Cement, and its compressive strength is set to a reference value (100).
The same compression strength ratio is also shown in the table.

[0038]

[Table 2]

From Table 2, the following matters are clear. 1) The P ₂ O ₅ content is [0.1% by mass → 0.8% by mass →
1.7 mass%], the compressive strength ratio also becomes [1
00% → 80% → 58%] (Comparative Example 1
~ 3).

2) When comparing the inside and outside of the specified ranges of HM and SM of the cement clinker, when the content of P ₂ O ₅ is 5.0% by mass or less, within the specified range, it is possible to improve the reduction rate of the compressive strength. Effective (Example 7 (4.7% by mass), Comparative Example 5 (5.5% by mass)). When the P ₂ O ₅ content is approximately the same, the compression strength ratio is improved to [80% → 90%] within the specified range (Example, Comparative Example 2). HM, a prescribed outside of SM P ₂ O ₅ content: If the compression strength in the case of 0.8 wt%, to express the compressive strength of the same degree adjusted in defining the two ratios, P ₂ The O ₅ content can be increased to 4.7% by mass (Example 7, Comparative Example 2).

3) Even if it is within the range defined by HM, S
When M is out of the specified range, the strength reduction ratio cannot be improved (Comparative Example 4). If the HM is too high, as described above, the heat of hydration is increased and the fluidity is reduced, which adversely affects other properties, which is not preferable.

4) The total SO ₃ amount of the cement composition is 1.5
When it is in the range of 3.0% by mass, the rate of strength reduction is improved (Examples 6, 7 and Comparative Examples 6, 7).

[0043]

As described in detail above, the present invention relates to a cement clinker obtained by firing a blended raw material containing a phosphorus-containing waste, wherein the clinker has a P ₂ O ₅ content, And the range of the ratio of one component to two of the silicic acid ratio is limited, whereby the cement composition manufactured from the cement clinker (total SO ₃ amount: 1.5
3.0 wt%), despite high content of P ₂ O _5, it is possible to improve the reduction in compressive strength due to P ₂ O _5, blend waste into formulation material The effect is that the amount can be increased.

Due to the above effects, phosphorus-containing waste such as sewage sludge and incinerated ash can be used in large quantities as a raw material for cement clinker as one of its treatment methods. The contribution to environmental improvement is significant.

Continuing on the front page (72) Inventor Kenichi Honma 2-4-2 Daisaku, Sakura City, Chiba Pref. Central Research Institute, Inc. (72) Inventor Makihiko Ichikawa 2-4-2 Daisaku, Sakura City, Chiba Pref. Inside the Central Research Laboratory Co., Ltd. (72) Inventor Kiyoshi Kobuchi 1-1, Asano-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Pref. Cement Corporation (72) Inventor Hiroyuki Yamaguchi 1-1, Asano-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Inside the corporation

Claims (4)

[Claims] 1. A cement clinker obtained by calcining a blended raw material containing a phosphorus-containing waste, wherein the cement clinker has a P ₂ O ₅ content of 0.3 to 5.0 mass% and a hydraulic modulus (HM) )
Is 2.16 to 2.40, and the silicic acid ratio (SM) is 1.
Cement clinker characterized by being less than 3 to less than 2.4. 2. The cement clinker according to claim 1, wherein the waste is at least one selected from sewage sludge, sewage sludge incineration ash, municipal waste incineration ash, and steelmaking slag. 3. The SiO used for blending the compounded raw material
_2. The cement clinker according to claim 1, wherein the raw material is coal ash. 4. A cement clinker according to claim 1, wherein gypsum is mixed and pulverized so that the total SO ₃ amount is 1.5 to 3.0% by mass, or A cement composition characterized in that clinker and gypsum are individually ground and mixed.