JPH0764603B2 - Method for crushing cement clinker etc. by vertical roller mill - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for pulverizing cement clinker and the like by a vertical roller mill, and more particularly, a cement clinker or a mixture of cement clinker and gypsum (hereinafter “ Cement clinker, etc. ")
The present invention relates to a crushing method capable of suppressing the occurrence of vibration of a mill, increasing the crushing ability of the crusher, reducing the power consumption rate, and supplying cement of good quality.

[Prior Art] In a vertical roller mill for crushing cement raw material, coal, limestone, ore, etc., as shown in FIG. 1, the raw material to be crushed is fed from a feed conveyor 6 through a feed chute 7 to a casing 2
It is supplied onto the rotating crushing table 3 provided at the inner bottom portion of the crusher, and is crushed by being squeezed by the crushing table 3 and the crushing roller 4 which is driven by the upper surface of the crushing table 3 and is driven to rotate. The crushed material is conveyed by air flow to the classifier 5 provided in the upper part of the casing 2 by a gas jet introduced from the ventilation duct 11. Classification is performed by rotation of the classifier 5, and a product (fine powder) having a required fineness is discharged from the upper part to the outside of the mill 1 together with the gas, and is collected by a dust collector (not shown). Therefore, the number of revolutions of the classifier 5 and the amount of jet gas from the ventilation duct 11 are set so as to obtain a desired fineness. On the other hand, the coarse powder is returned to the crushing table 3 again,
It is crushed with New Feed. In FIG. 1, reference numerals 8 and 9 denote a stone discharging chute and a stone discharging transport machine, respectively. Also, 10
Is a bucket elevator for returning the discharged stones from the transport machine 9 to the chute 7.

[Problems to be Solved by the Invention] In the crushing of cement clinker and the like, it is necessary to obtain a fine crushed product as compared with the crushing of cement raw materials and coal. For this reason, conventionally, crushing is performed by increasing the pressing pressure of the crushing roller 4 or increasing the number of rotations of the classifier 5.

However, in this case, the amount of the powder or granules retained in the mill 1 increases, and the cement clinker or the like, which is sandwiched between the crushing table 3 and the crushing roller 4 and forms a crushing layer, has coarse particles and fine particles. Depending on the balance between the amounts of coarse particles and fine powder, the crushing roller 4 may slip and the mill 1 may vibrate, resulting in an inoperable operation.

In order to suppress the occurrence of this vibration, conventionally, diethylene glycol or triethanolamine has been added to the raw material. However, such a method is not very effective in increasing the pulverizing capacity and reducing the electric power consumption. I can't get it.

[Means for Solving Problems] The present invention provides the cement clinker or a mixture of cement clinker and gypsum, which is maintained at a temperature of 120 to 250 ° C.,
Water is added in an amount of 0.5 to 2% by weight and diethylene glycol in an amount of 0.01 to 0.1% by weight, and pulverized while being dried with cold air.

The present inventors, as a result of investigating the cause of vibration occurrence when crushing cement clinker and the like by a vertical roller mill, hard and dry and spherical particles like cement clinker, because the friction coefficient is small, When crushing by squeezing between the rotary table and the crushing roller, the crushing roller driven and rotated by the crushing table causes slip,
We have found that this is the cause of vibration.

Therefore, in order to suppress the occurrence of this vibration, as a result of further studies, when crushing hard and dry powder-like cement clinker with a vertical roller mill, an appropriate amount of water that does not affect the quality is used. By adding a mixed solution of ethylene glycol and diethylene glycol to a high temperature cement clinker, etc. and performing dry pulverization with air at room temperature, the state of biting into the pulverizing roller is improved, vibration is prevented, the mill operation is stable, and It has been found that the crushing amount is increased, the electric power consumption rate is reduced, and good quality cement can be obtained.

The method for crushing cement clinker by the vertical roller mill of the present invention has been completed based on these findings.

Hereinafter, the present invention will be described in detail.

According to the method of the present invention, when crushing cement clinker or the like in a vertical roller mill 1 as shown in FIG. 1, for example, a specific amount of water such as high temperature cement clinker and diethylene glycol are added and dried with air at room temperature. It is a thing.

As a method for adding water and diethylene glycol to cement clinker, etc., water and diethylene glycol are added to the cement clinker supplied to the mill.

 Add to gypsum fed to mill.

Add to the mixture of cement clinker and gypsum fed to the mill.

 Spray inside the mill.

There is a method such as. Of these, the method (1) and (2) are the most trouble-free and effective. When water and diethylene glycol are added, they may be added separately, or may be added as an aqueous solution of diethylene glycol diluted with water, and no significant difference is observed in the effects by either method. When the methods (1) to (4) are adopted, it is preferable that water or the like is supplied on the conveyor 6, but it may be supplied at another place.

If the amount of water added is too small, the effect is not obtained, and if it is too large, there is no difference in the effect, and on the contrary it may adversely affect the quality of the cement. 0.5 to 2% by weight.

From the viewpoint of the effect of addition and cost, the amount of diethylene glycol added is 0.01 to 0.1% by weight of cement clinker, etc.
And

In the method of the present invention, water and diethylene glycol are added to a cement clinker or the like at a high temperature (120 to 250 ° C.) and the mixture is dried and pulverized with air at room temperature. The necessity of keeping the cement clinker and the like in a high temperature state in this case is as follows.

Compared to ball mills, roller mills generate less crushing heat inside the mill, and the crushed products are transported to the outside by ventilation in the mill and are collected by a dust collector.
Compared to ball mills, the amount of air blown by the mill per product weight is large.
For this reason, the crushed product of the vertical roller mill is kept at a low temperature, and when water or the like is added to the cement clinker or the like, the amount of evaporation is small and the quality of the cement may be affected. Therefore, in the method of the present invention, the evaporation of water is promoted by raising the temperature of the crushed cement clinker or the like.

In the method of the present invention, by crushing the clinker or the like at 120 to 250 ° C., since the clinker or the like is at a high temperature, the evaporation of added water proceeds, without using hot air.
It can be sufficiently pulverized by drying with a gas at room temperature.

FIG. 2 is a system diagram showing an example of a crushing system in which a clinker cooler for a cement kiln and a vertical roller mill which are suitable for carrying out the present invention are combined.

In FIG. 2, the raw material preheated by the preheater 25 is supplied into the rotary kiln 20 and fired. The sintered clinker is introduced into the cooler 19 and cooled by the air blown from the blower 23. This clinker is introduced into the mill 1 from the conveyor 6 and the chute 7 via the high temperature clinker transporter 21, the clinker storage tank 16, and the clinker constant quantity feeder 14. Gypsum is supplied onto the conveyor 6 through the gypsum storage tank 17 and the gypsum constant quantity feeder 15. The fine powder generated by the pulverization in the mill 1 is collected by the bag filter 12. Reference numeral 13 is an Egi sauce fan, 18 is a hot air generating furnace, 22 is a clinker cooler exhaust heat gas duct, and 24 is a room temperature air duct.

According to such a grinding system, the clinker cooler 19
Water and diethylene glycol can be added to the high temperature clinker discharged from the chiller, and the crushing can be performed by cooling with normal temperature air, and the crushing efficiency of the vertical roller mill 1 can be improved and the power consumption of the clinker cooling fan 23 can be reduced. The cement manufacturing cost can be reduced.

[Operation] When crushing clinker or the like with a normal ball mill, a method of adding diethylene glycol as a crushing aid to enhance crushing efficiency is well known. Even in a vertical roller mill having a different crushing mechanism, the addition of diethylene glycol can improve the crushing efficiency for crushing cement clinker and the like. However, diethylene glycol is expensive, and the addition amount is usually 0.01 to 0.03% by weight based on the weight of cement when pulverizing ordinary Portland cement. If it is too much, the fluidity of the cement increases excessively, which may cause trouble. Therefore, compared with the case of adding no conventional diethylene glycol alone,
With the same fineness, the pulverization amount increases by 5 to 10%, and the electric power consumption rate decreases by about 5 to 10%, and a sufficient effect cannot be obtained.

On the other hand, when water is also used as a grinding aid as in the present invention, vibration of the mill can be suppressed, the grinding performance can be improved, and the electric power consumption can be reduced at a low cost. By promoting the evaporation of water by the high temperature, it is possible to obtain a high quality cement finished crushed product without affecting the quality.

Then, by adding diethylene glycol together with water, the vibration of the mill is suppressed even more effectively due to the synergistic effect of the grinding aid effect of diethylene glycol and the grinding aid effect of water, and a large increase in the grinding amount. It is possible to significantly reduce the power consumption rate.

By the way, in the case of cement, not only the fineness but also the particle size composition of the product is important in terms of quality. The conventional addition of only diethylene glycol improves the dispersibility of the pulverized product in the mill, and the particle size distribution of the cement taken out to the product side by the classifier tends to have a narrow particle size configuration with many intermediate particles.

On the other hand, in the case of adding water together according to the present invention, the crushing state of the crushing roller is improved, and fine powder is easily generated to obtain a product having a wide particle size distribution. That is, diethylene glycol is
It is effective in improving the dispersibility of the product, and water is effective in making fine powder.

From this, in the present invention, by simultaneously adding water and diethylene glycol and pulverizing, the synergistic action of the effects of both of these facilitates control of the particle size composition, and a ball mill crushed cement having a wide particle size distribution range. It is easy to obtain a product with a particle size configuration similar to that of, and the quality of cement is the same as or better than that of a ball mill crushed product.

Moreover, since high-temperature cement clinker or the like is crushed, it is possible to accelerate the evaporation of added water to obtain a crushed product of good quality, and to perform cooling dry crushing with air at room temperature, which improves the crushing efficiency. As a result, the power consumption of the clinker cooling fan can be saved, and the cement manufacturing cost can be reduced.

[Examples] Examples will be described below. In addition, in the following examples, addition of water and the like was performed on the conveyor 6.

Example 1 When crushing ordinary Portland cement with a vertical roller mill shown in FIG. 1, the Blaine specific surface area of the cement was compared between the case where no grinding aid was added and the case where 0.02% by weight of diethylene glycol and 1% by weight of water were added. The relationship between the crushing ability and the power consumption rate was compared. The clinker temperature was about 150 ° C, and the temperature of the blown airflow from the duct 11 was room temperature (about 20 ° C).

The results are shown in FIGS. 3 and 4.

As is clear from FIGS. 3 and 4, for example, when crushing ordinary Portland cement having a Blaine specific surface area of 3000 cm ² / g with a vertical roller mill, 0.02% by weight of diethylene glycol and 1% by weight of water are added according to the present invention. When dry pulverization is carried out, the pulverizing capacity is increased by about 20% and the power consumption rate is reduced by about 20% compared to the case of no addition.

[Effects of the Invention] As described in detail above, the crushing method of the present invention has the following excellent effects.

It is possible to suppress the occurrence of vibration when crushing cement clinker or the like with a vertical roller mill.

The crushing ability is greatly improved and the power consumption rate is also significantly reduced.

The vertical roller mill enables the finishing crushing of cement with the same quality as the cement crushed by the ball mill.

The high temperature clinker can be crushed, and the power consumption of the clinker cooler can be reduced.

It is possible to effectively use the exhaust heat gas at a relatively low temperature in the factory such as a clinker cooler as a dry pulverization heat source.

Therefore, according to the method of the present invention, it is possible to efficiently obtain a high-quality crushed cement finished product at low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a vertical roller mill, FIG. 2 is a system diagram showing an example of a grinding system in which a cement clinker cooler and a vertical roller mill are combined, and FIG. Fig. 4 is a graph showing the relationship between the Blaine specific surface area and the pulverizing ability when diethylene glycol is added at the same time. Fig. 4 shows the relationship between the Blaine specific surface area and the power consumption rate when no auxiliary agent is added and when water and diethylene glycol are added at the same time. It is a graph which shows. 1 ... Vertical roller mill, 2 ... Mill casing, 3 ... Grinding table, 4 ... Grinding roller, 5 ... Classifier, 6 ... Supply conveyor, 7 ... Supply chute, 8 ... Exhaust stone chute, 9 ... Exhaust transporter, 10 ... Bucket elevator, 11 ... Ventilation duct, 12 ... Bag filter, 13 ... Exhaust fan, 14 ... Clinker quantitative feeder, 15 ... Gypsum constant feeder, 16 ... … Clinker storage tank, 17 …… Gypsum storage tank, 18 …… Hot air generator, 19 …… Clinker cooler, 20 …… Rotary kiln, 21 …… High temperature clinker transport machine, 22 …… Clinker cooler Waste heat gas duct, 24… … Room temperature air duct, 25… Preheater.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-142856 (JP, A) Cement Association Crushing Committee Report (S-11) November 10, 1978 (Published by Cement Association) 46-47 Powder and Industry Vol. 5. No. 2 February 1973 Powder and Industry Publishing P.P. 61-P. 74

Claims (1)

[Claims] 1. Cement clinker or a mixture of cement clinker and gypsum is pulverized by a vertical roller mill for crushing an object to be crushed by a crushing table that rotates and a crushing roller that rotates while being driven by the upper surface of the crushing table. In doing so, 0.5-2% by weight of water and 0.01-diethylene glycol were added to the cement clinker or the mixture of cement clinker and gypsum held at a temperature of 120 to 250 ° C.
A method for pulverizing cement clinker etc. by a vertical roller mill, which comprises adding 0.1% by weight and pulverizing while drying with air at room temperature.