JP2775486B2 - Cement clinker grinding method - Google Patents

Description

The present invention relates to a method for pulverizing a cement clinker.

b. Conventional technology Conventionally, various Portland cements are prepared by mixing raw materials such as limestone and clay in a raw material pulverizing process so as to have a target composition, then pulverizing the powder into a powder, and then firing the powdered raw material in a firing process to form a block. In the finish grinding step, an appropriate amount of gypsum is blended with the clinker, and the mixture is finished and ground again into a powder.

Here, a storage facility for the pulverized raw material is provided between the raw material pulverizing step and the baking step, and a clinker storage facility is provided between the baking step and the finish pulverizing step.

Also, for the finish grinding of such cement clinker,
Conventionally, a ball mill has been mainly used, but in recent years, a ball mill provided with a preliminary pulverizing device using a roller mill or a roll press has begun to be used.

c. Problems to be Solved by the Invention However, in the above-described conventional technology, when two or more types of Portland cement are produced separately, the necessity of changing the chemical composition makes it difficult to use different types of Portland cement in the raw material crushing step and the firing step. , And the milled raw materials and clinker produced for each variety had to be stored separately.

For this reason, in the operation of the raw material pulverizing step and the firing step, it is troublesome to switch the product type, and there has been a problem in the processing of the intermediate product produced in the switching process. Furthermore, it is uneconomical in terms of equipment because it is necessary to provide dedicated storage equipment for each of the crushed raw materials and the clinker varieties.

d. Means for Solving the Problems The present invention has been made in view of the above-mentioned problems of the prior art, and can produce two types of cements having different components from one type of former clinker. In addition to the cement that is almost the same as the composition of the original clinker, it is intended to provide a completely new method of pulverizing a cement clinker capable of simultaneously producing a small amount of high-grade cement with high strength at an early stage. After primary pulverization, the mixture is classified into fine-grain clinker and coarse-grain clinker, and these fine-grain clinker and coarse-grain clinker are separately and secondarily pulverized to obtain different types of cement products.

e. Action The method of pulverizing the cement clinker according to the present invention is as follows.
As shown in the figure, the cement clinker a is pulverized by a primary mill 1 and the resulting pulverized product is classified by a classifier 10. At this time, components are unevenly distributed between the classified coarse-grained portion and the fine-grained portion.

That is, compared to the original clinker, fine particles have relatively more pulverizable C ₃ S (alite), and conversely less pulverizable C ₂ S (belite), and are unevenly distributed.

Here, since C ₃ S contributes to the development of short-term strength and C ₂ S contributes to the development of long-term strength, respectively, a necessary amount of gypsum b is added, and a small amount of fine-grain clinker and a majority of coarse-grain clinker are added. Separately pulverized to a predetermined degree of fineness by secondary mills 2,2, it is possible to produce cement close to the composition of the original clinker from coarse clinker, and a small amount of high-grade cement with high strength from fine clinker. Can be manufactured.

f. Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments, and other configurations may be obtained by combining the components of each embodiment. Or a part of the design is changed.

FIG. 2 shows a first embodiment of the present invention.
In the figure, a primary pulverizing device 1 and a secondary pulverizing device 2 are provided when viewed from the clinker flow direction. The primary mill 1 uses a roller mill 3, and the secondary mill 2 uses ball mills 4 and 5.

The cement clinker is withdrawn from the storage bin 6 and sent to the roller mill 3 of the primary crusher 1 by the conveyor 7.

The roller mill 3 has no internal separator, and all the pulverized products are supplied to the classifier 10 via the screen 9 by the bucket elevator 8.

The classifier 10 can change the setting of the classification point depending on the uneven distribution of the clinker component, and can control the quality of the fine-grain clinker on the high-quality side.

The coarse-grain clinker and the fine-grain clinker classified by the classifier 10 are supplied to separate ball mills 4 and 5 as secondary grinding units 2 on conveyors 11 and 12, respectively.

At this time, independent gypsum supply equipments 13 and 14 are provided for the coarse clinker and the fine clinker, respectively. A larger amount of gypsum is blended than clinker.

On the other hand, the coarse-grained clinker is provided with equipment 15 that can mix additives such as slag as necessary.

In the secondary pulverizer 2, the fineness is adjusted in order to exhibit the characteristics of each product cement, but in general, the fine clinker is finely pulverized by a coarse clinker.

In the case of the above-described embodiment, since the roller mill 3 is used for the primary pulverization, the power consumption per unit of the pulverization is small.
In addition, in the secondary milling ball mills 4 and 5, the particle size of the feed is sufficiently small and the optimum medium size can be selected according to the product fineness. Can be.

3 to 6 show another embodiment of the present invention.

FIG. 3 shows that gypsum is compounded in the primary grinding stage, a roll press 18 is used in the primary grinding device 1, a roller mill 20 is used as the secondary grinding device 2 for the coarse-grain clinker, and a secondary grinding device is used for the fine-grain clinker. This is an example in which the ball mills 5 are applied to No. 2 respectively.

When gypsum is supplied in the primary grinding stage, gypsum generally tends to be finer than clinker, so fine clinker classified by classifier 10 contains more gypsum than coarse clinker. .

According to this arrangement, the amount of gypsum on each of the fine-grain side and the coarse-grain side cannot be controlled, but by mixing gypsum in the primary grinding stage, gypsum supply equipment and gypsum pretreatment are simplified. If the weight ratio of the fine-grain clinker to the coarse-grain clinker is relatively large, such a configuration can be adopted depending on the type of gypsum.

In addition, the roll press 18 as the primary pulverizer 1 is compact in terms of equipment and has more flexibility in arrangement than a roller mill.

Also, the work volume of primary grinding in the roll press 18 was increased,
In the case of relatively fine primary pulverization, it is necessary to operate with a high pressure applied between the rolls, and the primary pulverized product is agglomerated into a cake, and is supplied to the subsequent classifier 10. Before, these crushers to crush these cakes into powder
19 is arranged.

When the primary pulverization work is reduced and the primary pulverization is performed relatively coarsely, there is no need to install a pulverizer 19 because the roll press 18 does not agglomerate into a cake.

As the secondary pulverizer 2, a roller mill can be used in addition to a conventional ball mill. In particular, by using the roller mill 20 on the coarse particle side having a large amount of processing, the power consumption per unit of the entire system can be reduced. It is suitable to use a ball mill 5 on the fine grain side where a small amount of processing is required and a fine product fineness is required.

FIG. 4 shows an example in which gypsum is blended and pulverized firstly, and then gypsum is additionally blended into a part of the classified fine clinker.

In mixing gypsum into the classified fine clinker,
Fine-grained clinker has already become quite fine, and if gypsum is additionally blended into this and then ground secondarily, gypsum in the final cement product will remain in a relatively coarse state, and as a setting retarder The effect of can not be fully exhibited. For this reason, in this embodiment, the gypsum mixed with the fine-grain clinker is separately pulverized before the mixing.

In addition, only a part of the fine clinker classified by the classifier 10 is used for the production of high-grade cement, and the other part is combined with the coarse clinker and secondarily pulverized. Can be easily adjusted.

Further, in the classifier 10, the ultrafine powder collected by the dust collector 22 accompanying the airflow used for classifying the fine-grain clinker and the coarse-grain clinker can be combined with the fine-grain clinker. Since the fine powder does not always have a composition having high early strength, it is combined with the coarse clinker.

 Note that the broken lines indicate the flow direction of the airflow.

FIG. 5 shows another embodiment in which, when the cement clinker is primarily pulverized by the roll press 18, the pulverized product is kept within a range in which the pulverized product does not agglomerate.

That is, the primary pulverizing work in the roll press 18 is reduced, and the difference in component segregation between the fine clinker and the coarse clinker after classification is increased.

However, in this case, since the amount of the uncrushed clinker that passes through the roll press 18 increases, a part of the primary pulverized product can be circulated and supplied to the roll press 18 by known means.

In addition, since the secondary grinding work of the coarse clinker classified by the classifier 10 increases, the secondary grinding itself is performed by a roll press 18.
And a ball mill 4 in combination.

Further, by providing the primary grinding device 1 with a circulation device, the maximum particle size of the coarse clinker is reduced, so that not only the fine clinker but also the gypsum to be blended with the coarse clinker is primarily ground before blending. It has become so.

FIG. 6 shows another embodiment of the circulating means in the primary grinding device 1.

The primary pulverized clinker is supplied to a primary classifier 24, where the massive clinker which falls down without being able to ride on the air stream for classification is circulated and supplied to a roll press 18 which is the primary pulverizer 1.

The clinker accompanying the air stream for classification is introduced into the secondary classifier 25, where the coarse clinker is separated, and the fine clinker is sent to the subsequent dust collector 22 together with the air stream discharged from the secondary classifier 25. Introduced and separated here.

The size of the mass clinker circulated to the roll press 18 is adjusted by selecting the speed of the classifying airflow in the primary classifier 24.

Further, a crusher can be combined with the primary classifier 24.

Next, specific examples of products obtained by the pulverization method of the present invention will be described.

Table 1 shows that using a roll press as the primary crushing device, the ordinary bolt land cement clinker fired in a rotary kiln with a suspension preheater was first crushed by the above roll press, and the resulting cake-like clinker was crushed. After that, in the case where the fine clinker and the coarse clinker were classified in a laboratory by a sieve having a mesh of 45 μm, the chemical analysis values of the original clinker, the fine clinker, and the coarse clinker were used. The calculated mineral composition and component ratio are shown.

The weight ratio of the fine-grain clinker is 17.1% of the original clinker.
Met.

As can be seen in this table, fine-grain clinker has significantly increased C ₃ S compared to the original clinker, and conversely, C ₂ S has been halved,
Clinker mineral segregation is remarkable.

Also, regarding MH (hydraulic modulus) and LCF (lime saturation), a clear difference is observed between the original clinker and the fine clinker.

The fine-grain clinker having such a composition can be sufficiently used for the production of an early-strength cement.

On the other hand, the coarse clinker occupies 82.9% by weight, and there is almost no difference in the chemical composition, mineral composition, and component ratio from the original clinker. Can obtain cement which is not different in quality from the cement produced from the original clinker.

In addition, in the fine-grain clinker, F-CaO (free lime), which is an element causing expansion of the concrete, is significantly reduced as compared with the original clinker. This is because, in a clinker fired by a conventional manufacturing method, if an attempt is made to produce a clinker having a high LSF by blending raw materials, F-CaO tends to increase inevitably, but according to the method of the present invention, the LSF is high. Nevertheless, a clinker with a low F-CaO can be obtained.

That is, according to the pulverizing method of the cement clinker of the present invention, a cement having almost no difference in quality from the original clinker, a high strength and a high strength can be obtained from one kind of the original clinker.
-It has been found that two types of cements, high-grade cements with low CaO, can be produced simultaneously.

Incidentally, the degree of segregation of components into the fine-grain clinker is affected by the operating conditions of the primary grinding equipment and the classifier. This is shown in Table 2.

Table 2 shows an example of experimental data obtained by investigating the effects of primary pulverizing conditions and classification conditions on the segregation state of clinker minerals.

The primary pulverization is performed by a roll press, and the pulverization pressure in the table is based on the definition of Jehnert. The mineral segregation state is 1
The whole amount of the next pulverized product is classified by a sieve having a classified particle size, and is contained in the fine-grain clinker below the sieve compared to the coarse-grain clinker on the sieve
C ₃ S and C ₂ S content of the increment (+) or decrease (-) are indicated by.

From Table 2 and various other experiments, it is necessary that the primary grinding of the original clinker is appropriately coarse, and when the primary grinding is performed finely, the degree of segregation of components into the fine-grained clinker decreases. , F-CaO may increase. Conversely, if the primary pulverization is too coarse, not only the required amount of fine-grain clinker cannot be obtained, but also the required power consumption in all the pulverization equipment including the secondary pulverization equipment increases.

From these viewpoints, it is suitable to select the 80% passage diameter of the primary pulverized clinker to be 1 mm or more and 10 mm or less, particularly 5 mm or less.

Next, when the classification point of the primary pulverized clinker is increased, the degree of segregation of the components into the fine-grain clinker generally decreases,
Depending on the type of clinker, the degree of segregation of components may be reduced even with an ultrafine clinker of about 20 μm or less. Conversely, if the classification point is too small, the high-grade cement obtained by secondary pulverizing the fine-grained clinker becomes too fine, so that the properties of the cement in terms of workability at the time of kneading and the like deteriorate.

From these viewpoints, the 80% passage diameter of the fine clinker is 30
It is suitable to select a thickness of not less than μm and not more than 300 μm, especially not more than 100 μm.

Furthermore, the weight ratio of the fine-grain clinker determined by the combination of the particle size of the primary pulverized clinker and the classification point is such that if it is too large, the quality of the high-grade cement produced from the fine-grain clinker deteriorates, and The quality of cement produced from clinker is also greatly different from that of cement produced from former clinker.

Therefore, it is appropriate that the weight ratio of the fine-grain clinker is limited to 30% or less, particularly 15% or less based on the weight of the original clinker.

As for the type of the primary crusher, it is more suitable to use a compression crusher such as a roller mill and a roll press than a shock crusher such as a hammer crusher in terms of a component segregation surface in a fine-grain clinker. In addition, as a secondary pulverizer for fine grain clinker, from the aspect of quality based on the particle size composition of the product cement,
An impact mill such as a ball mill and a jet mill is suitable.

f. Effects of the Invention As described above, the present invention classifies the original clinker at the stage of primary pulverization, so that the clinker having a different chemical composition can be obtained.
Cinders of different varieties are obtained, and each is secondarily crushed under different conditions to produce two types of cement.
It is possible to produce not only cement which is comparable to the cement produced by the conventional method of producing one kind of cement from the original clinker of the kind but also simultaneously produce a small amount of high-grade cement with high strength.

In addition, troublesome work of changing the kind in the operation of the raw material pulverizing step and the firing step, which is a problem in producing two kinds of cement by the conventional production method, is eliminated, and there is no intermediate product produced in the changing step. , The processing becomes unnecessary.

Further, in terms of equipment, storage equipment required according to the type of pulverized raw material and clinker can be used for only one type, which is economical.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the operation of the present invention. FIG. 2 to FIG. 6 are conceptual diagrams showing an apparatus used for carrying out the present invention. a ... cement clinker, b ... gypsum, 1 ... primary mill (primary grinding device), 2 ... secondary mill (secondary grinding device), 3 ... roller mill (without internal separator), 4,5 …… Ball mill, 6… Cement clinker supply bin, 7,11,12 …… Conveyor, 8 …… Bucket elevator, 9 …… Screen, 10… Classifier, 13,14… Gypsum supply bin, 15 …… Slag supply bin, 16 Product cement A, 17 Product cement B, 18 Roll press, 19 Crusher, 20 Roller mill, 21 Intermediate hopper, 22 Dust collector, 23 Fan , 24… Primary classifier, 25… Secondary classifier, 26… Fine grain clinker, 27… Coarse grain clinker.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 7/52

Claims (16)

(57) [Claims] After the cement clinker is first pulverized, the cement clinker is classified into a fine clinker and a coarse clinker, and the fine clinker and the coarse clinker are separately and secondarily pulverized to obtain different types of cement products. Pulverizing method of cement clinker. 2. A method for pulverizing a cement clinker according to claim 1, wherein the cement clinker is first pulverized so that the 80% passage diameter is 1 mm or more and 10 mm or less. 3. A method for pulverizing a cement clinker according to claim 1, wherein the cement clinker is first pulverized so that the 80% passage diameter is 1 mm or more and 5 mm or less. 4. A fine grain clinker having an 80% passage diameter of 30 μm or more.
The method for pulverizing a cement clinker according to any one of claims (1) to (3), wherein the classification is performed so that the particle size is 300 μm or less. 5. A fine grain clinker having an 80% passage diameter of 30 μm or more.
The method for pulverizing a cement clinker according to any one of claims (1) to (3), wherein the classification is performed so that the particle size is 100 μm or less. 6. The cement according to claim 1, wherein the classification is performed such that the weight ratio of the classified fine clinker is 30% or less of the total clinker weight. Clinker grinding method. 7. The cement according to claim 1, wherein the classification is performed such that the weight ratio of the classified fine clinker is 15% or less of the total clinker weight. Clinker grinding method. 8. The method for pulverizing a cement clinker according to claim 1, wherein the primary pulverization is performed by a compression type pulverizer. 9. The method according to claim 1, wherein the secondary pulverization of the fine-grained clinker is performed by an impact-type pulverizer.
The method for pulverizing a cement clinker according to item (8). 10. A method for pulverizing a cement clinker according to any one of claims (1) to (9), wherein gypsum is added to each of the fine clinker and the coarse clinker after classification. 11. A method for pulverizing a cement clinker according to claim 10, wherein gypsum which has been separately pulverized is blended separately. 12. The method for pulverizing cement clinker according to claim 10 or 11, wherein the amount of gypsum to be added to the fine clinker is larger than that of the coarse clinker. 13. The method according to claim 1, wherein gypsum is blended into the cement clinker before the primary pulverization, and gypsum is further blended into the fine clinker after the classification. The method for pulverizing a cement clinker according to the above item. 14. The method according to claim 1, wherein the fine-grained clinker is finely secondary-crushed from the coarse-grained clinker.
Item 14. The method for pulverizing a cement clinker according to any one of Items 13 to 13. 15. The method according to claim 1, wherein an additive such as slag is blended with the coarse clinker. 16. A method for pulverizing a cement clinker according to any one of claims (1) to (15), wherein the chemical composition of the classified fine clinker is analyzed to adjust the degree of classification. .