JP6454061B2 - Raw material for low-temperature fired cement clinker and method for producing low-temperature fired cement clinker - Google Patents

Description

  The present invention relates to a raw material for low-temperature fired cement clinker that can be fired at a lower temperature than before without using a special raw material, and a low-temperature fired cement clinker obtained by firing the raw material.

  In recent years, energy-saving cement clinker that can be fired at a lower temperature than conventional methods and a method for producing the same have been proposed for the construction of a low-carbon society. These cement clinker is improved in easily baked property by a mineral component such as fluorine (see Patent Documents 1 to 3). Conventionally, it has been known that the clinker's flammability is affected by the particle size and blending amount of silica stone, and it has also been proposed to use a specific alternative to prevent deterioration of flammability (patent) Reference 4).

JP 2009-161212 A JP 2011-207633 A JP2011-207752A JP 2009-29679 A

  However, the existing technology requires specific mineralization components and alternative raw materials, and there are problems that it is difficult to procure raw materials and that the blending conditions are restricted. In the mass-produced cement industry, there is a demand for technology that enables low-temperature firing for general purposes.

  Therefore, an object of the present invention is to provide a raw material for a low-temperature fired cement clinker that can be fired at a lower temperature than before without using a special raw material. Another object of the present invention is to provide a low-temperature fired cement clinker obtained by firing this.

As a result of intensive studies to solve the above problems, the present inventors have pulverized coal ash used as a raw material for low-temperature fired cement clinker into a specific particle size, or mixed high-strength concrete. The present invention has been completed by using fine ash fly ash, which is used as a fly ash for adding wood and fly ash cement, as a raw material.
That is, the present invention is a raw material for low-temperature fired cement clinker containing 8 to 20% by mass of coal ash, and the coal ash has a particle group of 32 μm or more and 10% by mass or less, and an average particle diameter of 2 It is a raw material for low-temperature fired cement clinker characterized by being 10 μm to 10 μm. Such a raw material can effectively increase the calcination property of the cement clinker without using a special raw material such as a mineralizer.

  Moreover, it is more effective that the particle group of 48 μm or more of the coal ash is 2 mass% or less, the particle group of 24 μm or more is 17 mass% or less, and the particle group of 12 μm or more is 50 mass% or less.

  Moreover, the stable effect can be acquired as the said coal ash is the fly ash I class prescribed | regulated to JISA6201-1999.

The present invention also provides a low-temperature fired cement clinker obtained by firing the raw material for low-temperature fired cement clinker. Since this low-temperature fired cement clinker can be fired at a low temperature, it contributes to energy saving and CO ₂ emission reduction.

  According to the present invention, it is possible to provide a low-temperature fired cement clinker raw material that can be fired at a lower temperature than before without using a special raw material. This can contribute to the construction of a low-carbon society.

The amount of coal ash particles of 32 μm or more used in the examples and the cement clinker f. It is a related figure with CaO amount (free lime amount).

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The raw material for low-temperature fired cement clinker of the present invention is a raw material for low-temperature fired cement clinker containing 8 to 20% by mass of coal ash, and the coal ash has a particle group of 32 μm or more and 10% by mass or less, and The average particle size is 2 to 10 μm.

  Coal ash is generated from a coal-fired power plant or the like, and includes cinder ash, fly ash, clinker ash, and bottom ash.

  The content of coal ash is 8% by mass at the lower limit and 20% by mass is the upper limit, preferably 8 to 19% by mass, more preferably 9 to 18% by mass, and still more preferably 10 to 17% by mass. It is. If the coal ash content is less than 8% by mass, the effect of improving the calcination property cannot be sufficiently obtained. Moreover, when content of coal ash exceeds 20 mass%, there exists a possibility that the amount of melts of a clinker may become excessive and may interfere with manufacture.

  Moreover, it is important that the particle size of coal ash is 10% by mass or less in a particle group of 32 μm or more. Preferably it is 8 mass% or less, More preferably, it is 6 mass% or less, More preferably, it is 2 mass% or less. The average particle size is 2 to 10 μm or less, preferably 3 to 9 μm, more preferably 4 to 8 μm, still more preferably 4.5 to 7 μm, and most preferably 4.5 to 4.8 μm. is there. If the particle size of the coal ash is within this range, the effect of improving the easy calcination can be ensured.

  The particle size of coal ash is more effective when the particle group of 48 μm or more is 2 mass% or less, the particle group of 24 μm or more is 17 mass% or less, and the particle group of 12 μm or more is 5 to 50 mass%. The particle size of 48 μm or more is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. The particle size of 24 μm or more is preferably 14% by mass or less, more preferably 12% by mass or less, and further preferably 5% by mass or less. The particle size of 12 μm or more is preferably 5 to 45% by mass, more preferably 5 to 40% by mass, and still more preferably 7 to 30% by mass.

  As raw materials for low-temperature fired cement clinker other than coal ash, ordinary raw materials can be used. Specifically, limestone, silica stone, slag, construction generated soil, sludge, burning husk, dust, etc. can be used. Among these raw materials, the amount of limestone used is 60 to 80% by mass, preferably 65 to 75% by mass, and more preferably 70 to 75% by mass. Silica is 0.1 to 8% by mass, preferably 1.5 to 7% by mass, more preferably 2.0 to 6.8% by mass. Furthermore, the 1 or more types of raw material chosen from the group which consists of slag, construction generation | occurrence | production soil, sludge, a burning husk and soot and dust is 3-15 mass%, Preferably it is 5-12 mass%, More preferably, it is 7-10 mass%. good. If it is these ranges, the improvement effect of easy baking property is securable.

The composition of the raw material for low-temperature fired cement clinker is not particularly limited, and can be a normal Portland cement composition. However, in consideration of the low temperature firing which is the object of the present invention, the HM defined by the following formula is 2.4 or less, preferably 1.9 to 2.3, more preferably 2.1 to 2.2, and still more preferably Is preferably 2.12 to 2.16.
HM = CaO / (SiO ₂ + Al ₂ O ₃ + Fe ₂ O ₃ )
Incidentally, _CaO in the _{formula, SiO 2, Al 2 O 3} , Fe 2 O 3 is the mass% of each chemical composition, respectively contained in the raw material for cement clinker.
Further, the SM is desirably 2.2 to 2.7, preferably 2.3 to 2.6, and more preferably 2.58 to 2.62. It is desirable that IM is 1.6 to 2.0, preferably 1.7 to 1.9, and more preferably 1.75 to 1.85. If it is these ranges, the improvement effect of easy baking property is securable.

  Furthermore, it is preferable that the raw material for low-temperature fired cement clinker of the present invention uses fly ash type I defined in JIS A 6201-1999 as the coal ash. The fly ash type I is generally used as an admixture for high-strength concrete or high-fluidity concrete, or used as a raw material for fly ash cement. Compared to ordinary coal ash, it is expensive because the particle size and chemical composition are adjusted, but the quality is stable, and when used as a low-temperature fired cement clinker raw material of the present invention, the effect of improving easy fireability is stable. can get.

  The method for preparing the raw material for low-temperature fired cement clinker is not particularly limited, and coal ash having a predetermined particle size is prepared in advance, or fly ash type I specified in JIS A 6201-1999 is obtained. It is preferable to mix with raw materials for low-temperature fired cement clinker other than ash.

The low-temperature fired cement clinker of the present invention is a low-temperature fired cement clinker obtained by firing the raw material for the low-temperature fired cement clinker.
There is no particular limitation on the composition of the low-temperature fired cement clinker, but in order to ensure the same quality as when a normal cement clinker raw material is used, f. The amount of CaO is desirably 1.0% by mass or less.

The firing method of the low-temperature fired cement clinker is not particularly limited, and a general NSP kiln, SP kiln, or the like can be used. The firing temperature is not limited, but considering the low-temperature firing, which is the object of the present invention, the range of 1300 ° C. to 1400 ° C. is desirable, and thereby the effect of energy saving and CO ₂ emission reduction can be obtained.

  According to the raw material for low-temperature fired cement clinker and the low-temperature fired cement clinker of the present invention, it is extremely effective in the operation of adjusting coal ash to a predetermined condition without using a special raw material such as a mineralizer. In addition, the cement clinker can be fired at a low temperature. Conventionally, coal ash is a raw material that is easy to be fired, and since it is in a powder form, the particle size of coal ash itself has not been adjusted for the purpose of improving easy fireability (see, for example, JP2012-232867A). ). The present invention has been found that when a predetermined amount of coal ash is used, its particle size control has an extremely high calcination improvement effect.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

[Materials used]
Limestone, silica stone, blast furnace slag, and copper shells were used as raw materials for the low-temperature fired cement clinker in addition to coal ash. In addition, in order to adjust the Al ₂ O ₃ amount, SO ₃ amount and alkali amount of the low-temperature fired cement clinker, the reagents aluminum oxide, calcium sulfate dihydrate, sodium carbonate and potassium carbonate were used in combination. For the coal ash, several types of samples whose particle sizes were previously adjusted using a vibration mill were prepared, and commercially available fly ash type I was used.

The quality of these coal ash is shown in Table 1. Table 2 shows the particle size of the coal ash. In addition, the particle size of coal ash was measured using a laser diffraction type particle size distribution measuring device [manufactured by Seishin Enterprise, LMS-30 (Laser Micro Sizer)]. The sample dispersion solvent was ethanol, the sample dispersion time by ultrasonic before measurement was 60 seconds, the measurement time was 30 seconds, and the number of measurement repetitions was 2. From the obtained particle size distribution, a particle diameter-accumulated sieve mass% curve was created to determine the mass% of a predetermined particle group, and the particle diameter at which the accumulated sieve mass% was 50% was taken as the average particle diameter. Table 3 shows the particle sizes of limestone, quartzite, blast furnace slag, and copper shells measured in the same manner.

[Evaluation of easy firing of raw materials for low-temperature fired cement clinker]
F. In the case of heating up to 1550 ° C. in order to evaluate the easy firing of the raw material for low-temperature fired cement clinker. The amount of CaO was compared.
The above raw materials were blended under various conditions of HM = 2.14, SM = 2.60, IM = 1.84 so as to have a composition close to that of ordinary ordinary Portland cement. The obtained raw material for low-temperature fired cement clinker was put in an ultrafast heating furnace manufactured by Motoyama Co., Ltd. set to 1000 ° C., and immediately taken out after being heated to 1550 ° C. Here, the temperature was increased from 1000 ° C. to 1200 ° C. at 10 ° C./min, and from 1200 ° C. to 1550 ° C. was increased at 25 ° C./min. The cement clinker obtained by firing was subjected to f. By the Cement Association Standard Test Method JCAS I-01 “Method for Quantifying Free Calcium Oxide”. The amount of CaO was measured to evaluate easy baking. The results are shown in Table 4.

About said test result, the amount of particle | grains of 32 micrometers or more of the used coal ash, and f. The relationship with the CaO amount is shown in FIG. From FIG. 1, if the amount of particles of 32 μm or more is 10 mass% or less, f. It can be seen that the amount of CaO is sufficiently small and the calcination property is excellent.

[Confirmation of low-temperature firing of cement clinker]
Next, the cement clinker raw material of the present invention was fired at 1350 ° C., and f. The possibility of low temperature firing was evaluated by measuring the amount of CaO.
The above raw materials were blended under various conditions of HM = 2.14, SM = 2.60, IM = 1.84 so as to have a composition close to that of ordinary ordinary Portland cement. The obtained raw material for cement clinker was put into an ultra-fast heating furnace made by Motoyama Co., Ltd. set at 1000 ° C., heated to 1350 ° C., held for 30 minutes, and taken out. Here, the temperature was increased from 1000 ° C. to 1200 ° C. at 10 ° C./min, and from 1200 ° C. to 1350 ° C. was increased at 25 ° C./min. The cement clinker obtained by firing was subjected to f. By the Cement Association Standard Test Method JCAS I-01 “Method for Quantifying Free Calcium Oxide”. The amount of CaO was measured. The results are shown in Table 5.

  Comparative Example 7 using raw coal ash corresponding to conventional ordinary Portland cement was f. It is difficult to bake at 1350 ° C. due to the large amount of CaO. On the other hand, when the raw material for cement clinker of the present invention is used, f. It can be said that the CaO amount is sufficiently reduced and the cement clinker can be fired at a low temperature.

From the above, according to the raw material for low-temperature fired cement clinker of the present invention, it was confirmed that the easy-fireability of cement clinker is effectively enhanced without using a special raw material such as a mineralizer. In addition, the low-temperature fired cement clinker of the present invention can be fired at a low temperature, and can save energy and reduce CO ₂ emissions compared to the prior art.

Claims (7)

A raw material for low-temperature fired cement clinker containing 8-20% by mass of coal ash,
The coal ash is a raw material for low-temperature fired cement clinker, wherein a particle group of 32 μm or more is 10% by mass or less and an average particle diameter is 2 to 10 μm.   The low-temperature fired cement clinker according to claim 1, wherein a particle group of 48 µm or more of the coal ash is 2 mass% or less, a particle group of 24 µm or more is 17 mass% or less, and a particle group of 12 µm or more is 5 to 50 mass%. Raw material.   The raw material for low-temperature fired cement clinker according to claim 1 or 2, wherein the coal ash is a fly ash type I specified in JIS A 6201-1999.   The raw material for low-temperature fired cement clinker according to any one of claims 1 to 3, wherein the raw material for low-temperature fired cement clinker includes 60 to 80% by mass of limestone and 0.1 to 8% by mass of silica.   The raw material for low-temperature fired cement clinker includes 3 to 15% by mass of one or more selected from the group consisting of slag, construction generated soil, sludge, burning husks, and soot and dust, according to any one of claims 1 to 4. Raw material for low-temperature fired cement clinker. The composition of the raw material for the low-temperature fired cement clinker is such that HM is 1.9 to 2.3, SM is 2.2 to 2.7, and IM is 1.6 to 2.0. The raw material for low temperature baking cement clinker of any one of -5. A method for producing a low-temperature fired cement clinker, wherein the raw material for a low-temperature fired cement clinker according to any one of claims 1 to 6 is fired to obtain a low-temperature fired cement clinker.

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