JP2010120832A - Method for producing cement clinker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing cement clinker by using waste materials such as nonferrous slag and coal ash as raw materials in which the cement produced by using the obtained cement clinker is prevented from occurrence of a phenomenon that the mortar compressive strength lowers. <P>SOLUTION: The method for producing cement clinker comprises the steps of: measuring the Ti content of each of raw materials (minerals, waste materials, etc.) to be used for producing the cement clinker by X-ray fluorescence analysis; and adjusting a mixing ratio of each of raw materials so that the Ti content of the cement clinker obtained by firing becomes ≤1.0 mass% in terms of TiO<SB>2</SB>. When titanium slag having high Ti content is used as the raw material, a good result can be achieved particularly according to this method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a cement clinker. Specifically, the present invention relates to a method for producing a cement clinker that hardly causes adverse effects on cement physical properties such as compressive strength even when waste is used as a cement raw material.

  In recent years, the disposal of waste such as sewage sludge, sewage sludge incineration ash, municipal waste incineration ash, blast furnace water slag, blast furnace slow-cooled slag, and steel slag has become a social issue, and the amount of waste that will be more difficult to process in the future. Is expected to increase. For this reason, further research is necessary for the establishment, reuse, and recycling of effective waste disposal methods.

  Conventionally, in the manufacture of cement, recycling is performed by using the above waste as raw fuel.

Cement clinker is mainly composed of SiO ₂ , Al ₂ O ₃ , CaO, and Fe ₃ O _3, and the mineral ratio of these components, specifically C ₃ S (3CaO · SiO ₂ ), C ₃ A ( 3CaO.Al ₂ O ₃ ), C ₂ S (2CaO.SiO ₂ ) and C ₄ AF (4CaO.Al ₂ O ₃ .Fe ₃ O ₃ ) have a great influence on various physical properties of cement. well known.

  Various studies have also been conducted on the effects of small amounts of components. For example, the JIS standard (JIS R 5210) relating to Portland cement defines the amount of magnesium oxide, the amount of total alkali, the amount of chloride ions, and the like.

The free calcium oxide (free lime; f-CaO) When there is too much has been known that various problems occur (e.g., Patent Documents 1 and 2), and impact alone also P ₂ O ₅ content, Many studies have been made in combination with other components (see, for example, Patent Documents 3 to 5).

JP-A-8-34653 JP-A-7-267699 JP 2000-272939 A JP 2002-187747 A JP 2002-265242 A

  However, even if the raw material composition and the firing conditions are adjusted so that the composition (content) of each component whose influence is known is appropriate, in some cases, the mortar compressive strength is relatively poor. There is. Such a phenomenon occurs more frequently when a large amount of waste is used as a raw material. Therefore, in order to stably produce products having good physical properties, there is a problem that the amount of waste used must be suppressed. It was happening.

  Accordingly, an object of the present invention is to solve this problem, and to provide a method for stably producing a cement clinker having a good physical property that enables a large amount of waste to be used as a raw material.

As a result of diligent investigations in view of the above problems, the present inventors have found that the Ti component contained in the raw material is dissolved in other minerals when the amount is small, but if the amount exceeds a certain amount, CaTiO As a result of finding out that it precipitates as ₃ etc., and having further investigated, the present invention was completed.

That is, in the present invention, when preparing a cement clinker by preparing a plurality of types of raw materials and firing them, component analysis of each raw material used is performed, and based on the analysis results, Ti content in the cement clinker obtained after firing This is a method for producing a cement clinker in which the mixing ratio of the raw materials is adjusted so that the amount is 1.0% by mass or less in terms of TiO ₂ .

According to the present invention, it is possible to easily prevent CaTiO _{3 from} being precipitated in a cement clinker obtained by firing. As a result, it becomes easy to prevent the physical properties such as mortar compressive strength of the cement produced using the cement clinker from becoming relatively low.

  Therefore, even if it is a raw material with many Ti content, such as a waste, it becomes easy to adjust the usage amount with an appropriate range, and it is not necessary to suppress the waste usage amount more than necessary.

In the production method of the present invention, the components contained in each raw material are analyzed, and based on the analysis results, the Ti content contained in the cement clinker after firing is 1.0% by mass or less in terms of TiO _2. The composition of each raw material is adjusted (hereinafter, the cement clinker may be simply referred to as “clinker”).

As specifically shown in the examples and comparative examples described later, when the Ti content in terms of TiO ₂ in the clinker exceeds 1.0% by mass, for example, the mortar compressive strength is significantly reduced.

When the clinker having the same raw material composition and the same firing conditions is analyzed only in the Ti content, the porosity decreases until the Ti content in terms of TiO ₂ is 1.0% by mass. If it exceeds that, it becomes a certain value. In addition, in the X-ray diffraction of clinker, when the Ti content in terms of TiO ₂ exceeds 1.0 mass%, the presence of a substance identified as CaTiO ₃ begins to be confirmed, and the amount of other mineral components is also confirmed to change. (FIG. 1). From these facts, when the Ti content in terms of TiO ₂ is up to 1.0% by mass, the Ti component is solid-dissolved in the normal mineral component constituting the cement clinker. It is thought that it becomes impossible to melt and precipitates, and therefore affects other mineral compositions, and consequently affects the physical properties of cement.

From the viewpoint of obtaining better cement properties, it is preferable to adjust the blending ratio of each raw material so that the Ti content in the cement clinker obtained after firing is 0.5% by mass or less in terms of TiO _2. .

  On the other hand, from the viewpoint that a clinker with a low porosity is obtained, that is, a product with good shrinkage is obtained, the blending ratio of each raw material is adjusted to be in the range of 0.5 to 1.0% by mass. It is preferable to do.

The production method of the present invention is conventionally known except that the mixing ratio of each raw material must be adjusted so that the amount of Ti contained in the clinker after firing is 1.0 mass% or less in terms of TiO ₂ as described above. The method for producing cement clinker may be applied. That is, for example, if JIS standard Portland cement is manufactured, the clinker obtained by calcining with a cement kiln using mineral raw materials such as limestone, clay, silica, and iron oxide raw materials and various wastes and by-products as raw materials Gypsum and the like are mixed and pulverized to obtain a cement composition.

  Specific examples of usable waste and by-products include blast furnace slag, steelmaking slag, non-ferrous iron slag, coal ash, sewage sludge, purified water sludge, papermaking sludge, construction generated soil, foundry sand, dust, incineration fly ash, melting Examples include fly ash, chlorine bypass dust, wood scrap, waste white clay, waste, tires, shells, municipal waste and incinerated ash. is there).

  Among the wastes and by-products mentioned above, non-ferrous slag and coal ash, especially neutralized slag (titanium slag) produced during the titanium refining process, is used as a raw material because it is highly likely to contain a Ti component at a high concentration. The present invention is particularly useful for applying the present invention.

In carrying out the present invention, component analysis of each raw material is performed so that the amount of Ti contained in the clinker obtained after firing is 1.0% by mass in terms of TiO ₂ . In the present invention, the component analysis of the raw material does not need to analyze all the constituent components contained in the raw material, and it is only necessary to analyze and quantify the component that can achieve the above object. In the simplest case, the content of the Ti component in the raw material may be obtained by analysis.

In this case, the amount of Ti component contained in each raw material is matched to the form of Ti (TiO ₂ , double oxide with other metals, titanate, titanium sulfate, metal titanium, titanium alloy, etc.). The analysis may be performed by a known analysis method. Preferably, by adopting fluorescent X-ray analysis (according to JIS R 5204), it can be quantified with the required accuracy irrespective of the presence form of Ti.

  Of course, the analysis method is not limited to the fluorescent X-ray analysis, and may be quantified by a chemical analysis method defined in JIS R 5202, if necessary. In addition, when Ti is present as titanium metal or titanium alloy because a part of the raw material is a waste containing metal cutting powder, for example, the solution obtained by dissolving with inorganic acid-hydrofluoric acid is used. It can also be analyzed and quantified by atomic absorption analysis, IPC emission analysis or the like.

  When municipal waste or its incinerated ash is used as a raw material, a large amount of Ti in various forms may be contained. When such a raw material is used, its content can also be determined according to the method of a systematic analysis method of an unknown sample combined with dissolution by acid, alkali fusion, or the like.

In addition, as another analysis method for making the amount of Ti contained in the clinker become 1.0% by mass in terms of TiO ₂ , the content other than Ti is analyzed to obtain the content, and the content is calculated from the content. There is a method of adjusting the blending ratio of the raw materials so that the maximum value of Ti amount that can be contained in the clinker is within the above range. That is, various components other than Ti are analyzed to determine their contents, and if the mixing ratio of raw materials is determined so that the total of the clinker constituent components generated from the analyzed components exceeds 99% by mass, Ti is directly analyzed. At least, the Ti content in the cement clinker can be 1.0% by mass or less in terms of TiO ₂ .

  Further, for each raw material to be used, a method of directly analyzing the amount of Ti and a method of analyzing the amount of non-Ti component may be appropriately combined for analysis.

Note for a significant impact on _{C 3 S, C 3 A,} C 2 S and C ₄ mineral ratio of AF, etc. properties in clinker obtained after sintering as described above, these minerals ratio becomes the target range Analysis of components other than Ti needs to be performed in the same manner. This analysis can be generally performed by fluorescent X-ray analysis (JIS R 5204).

  Most preferred is a method of analyzing Ti and other components by fluorescent X-ray analysis.

Based on the amount of components contained in each raw material analyzed as described above, the ratio of minerals such as C ₃ S, C ₃ A, C ₂ S and C ₄ AF is within the target range, and the content of Ti component is The mixing ratio of each raw material is adjusted so as to be 1.0% by mass or less in terms of TiO ₂ . The mineral ratio depends on the hydraulic modulus (HM), silicic acid rate (SM), iron, etc., depending on what kind of cement (for example, ordinary Portland cement, early strong Portland cement, moderately hot Portland cement, etc.) is manufactured. What is necessary is just to set suitably so that a rate (IM) etc. may become a desired value.

In general, the Ti component contained in the raw material is contained in a form that is hardly volatile at a clinker firing temperature such as an oxide (TiO ₂ ) or a composite oxide, and in some cases, a titanium alloy or metallic titanium. Therefore, the Ti component contained in the raw material may be calculated to determine the blending ratio assuming that the entire amount is transferred to the clinker. Of course, when it is known that there is a Ti component that volatilizes in the raw material pulverization step or firing step and is not taken into the clinker, it is necessary to take into account that amount.

  Depending on the production scale and weighing accuracy, the composition of each component of the cement clinker after firing is usually controlled within the range of the calculated value ± 0.05% by weight if the calculation is performed according to the usual method for composition control during cement clinker production. it can.

  Thus, the raw material which adjusted the mixture ratio is baked and it is set as a cement clinker. The firing method is not particularly limited and may be appropriately selected from known methods. For example, firing is performed at a temperature exceeding approximately 1450 ° C. using a device capable of high-temperature heating such as a cement kiln represented by NSP kiln or SP kiln. It is common to do.

  The quantification of each component contained in the obtained cement clinker may be performed according to, for example, a chemical analysis method defined in JIS R 5202 or a fluorescent X-ray analysis method defined in JIS R 5204.

The cement clinker manufactured as described above and having a Ti content of 1.0% by mass or less in terms of TiO ₂ may be used as a cement according to a known method. For example, when using JIS standard cement, gypsum and, if necessary, grinding aid, blast furnace slag, siliceous mixed material, fly ash, calcium carbonate, limestone, etc. may be mixed and ground. Further, chlorine bypass dust may be mixed. By pulverization, the Blaine specific surface area is set to a value determined by the JIS standard or more, preferably about 2800 to 5000 cm ² / g.

  Further, if necessary, blast furnace slag, fly ash or the like can be mixed after pulverization to obtain blast furnace slag cement, fly ash cement or the like.

  Needless to say, the cement clinker obtained by the production method of the present invention may be used as a raw material for manufacturing cement other than JIS standards or a cement-based solidifying material.

  Hereinafter, although an example explains composition and an effect of the present invention, the present invention is not limited to these examples.

Cement raw materials were prepared by using the raw materials having the compositions shown in Table 1 and adjusting the blending ratio to change the content of TiO ₂ , and firing them at 1450 ° C. for 2 hours to obtain cement clinker. Gypsum was added to the cement clinker so as to have an SO ₃ content of 2.0 to 2.1% by mass, and the mixture was pulverized to have a Blaine specific surface area of 3450 to 3550 cm ² / g to prepare a cement.

Each measuring method is as follows.
(1) Measurement of chemical composition of raw material and cement clinker: Measured by fluorescent X-ray analysis in accordance with JIS R 5204.
(2) Measurement of mortar compressive strength: It was measured by a strength test based on JIS R 5201 standard.
(3) Measurement of porosity: It was carried out by the Archimedes method using an alcohol solvent.

  The neutralized soot is a neutralized soot generated during the titanium purification process.

Example 1
Calculated from the composition showing the analysis results in Table 1, Ti content in the clinker, adjusting the blending ratio of each raw material so that the 0.35 mass% in terms of TiO _2, calcined to cement clinker this Obtained. Table 2 shows the chemical composition of the obtained cement clinker and the mineral composition calculated by the Borg equation, and Table 3 shows the porosity.

  Further, gypsum was added to the cement clinker, and the mixture was pulverized to obtain cement. A mortar compressive strength test was conducted. The results are shown in Table 4.

Examples 2 to 4, Comparative Examples 1 and 2
Cement clinker was manufactured by changing the blending ratio of each raw material so that the Ti content in the final composition was different. At this time, in order to eliminate the influence of the composition other than the Ti content on the physical properties, HM, SM and IM were calculated so as to be substantially the same as the cement clinker obtained in Example 1, and other raw materials The blending ratio is also adjusted.

  Tables 2 to 4 show the measurement results of the obtained cement clinker and the cement produced using the cement clinker.

As shown in the above results, in Examples 1 to 4, the porosity decreased as the Ti content increased, but from the results of Comparative Examples 1 and ₂ , the Ti content in terms of TiO ₂ When the amount exceeds 1.0% by mass, the porosity is not changed. From this, it can be seen that an increase in the Ti content is effective in improving the sinterability, but a content exceeding 1.0 mass% does not contribute to the improvement in the sinterability.

The compressive strengths of Comparative Examples 1 and 2 are lower in each material age than in Examples, and particularly when the material age exceeds 3 days, it is reduced by 10% or more, so the TiO ₂ content is increased. If it is too much, it is clear that there is a problem in strength development.

FIG. 1 shows X-ray diffraction patterns having a TiO ₂ content of 0.34% (Example 1) and 2.11% (Comparative Example 2). In 2.11% (Comparative Example 2), a peak appears in the vicinity of 33 ° compared to 0.34% (Example 1). This is a peak identified in CaTiO ₃ , and it is presumed that CaTiO ₃ was generated with an increase in TiO ₂ content. This CaTiO ₃ peak is not confirmed in the cement clinker of Examples 2 to 4, but is confirmed in Comparative Example 1. From this, it can be seen that when the TiO ₂ content is 1.0% by mass or less, it is solid-dissolved, but when it is 1.0% by mass or more, TiO ₂ that is not solid-dissolved produces CaTiO ₃ . It is presumed that the production of CaTiO ₃ affects the suppression of the porosity reduction and the decrease in the strength development of the mortar compressive strength.

TiO ₂ content of 0.34% X-ray diffraction pattern diagram of (Example 1) and 2.11% (Comparative Example 2).

Claims (3)

When preparing multiple types of raw materials and firing them to produce cement clinker, component analysis of each raw material used is performed, and based on the analysis results, the Ti content in the cement clinker obtained after firing is converted to TiO ₂ The manufacturing method of the cement clinker which adjusts the compounding ratio of each raw material so that it may become 1.0 mass% or less.   The manufacturing method of Claim 1 which uses a waste material as at least one part of a raw material.   A method for producing cement, comprising producing a cement clinker by the method according to claim 1 and then mixing gypsum with the cement clinker.

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