JP5082818B2 - Method for treating chlorine compound-containing powder - Google Patents

Description

  The present invention is a technology related to a chlorine bypass system of a cement manufacturing apparatus, rapidly cooling a high-temperature gas containing a gaseous chlorine compound extracted from the cement manufacturing apparatus, and collecting it as a solid phase chlorine compound, Furthermore, it is related with the processing method of the chlorine compound containing powder collect | recovered to a cement manufacturing apparatus by granulating.

  In an era where society is demanding effective recycling of waste containing chlorine compounds as a resource, the cement industry is a technology that recycles waste containing chlorine compounds as a resource in large quantities. Has been developing. Chlorine bypass is a typical technique.

  An outline of a conventional chlorine bypass system is shown in FIG. The kiln exhaust gas is extracted from the rising duct 4 of the cement manufacturing apparatus, rapidly cooled and solidified by the extraction cooling device 5, and then the extracted material is collected by the dust collector 6. The collected solid-phase powder is transported to Patent Document 1 as it is and mixed with the clinker transport 7 at the exit of the clinker cooler 15 in the cement kiln 1 for recovery. Patent Documents 2 and 3 describe a method of collecting at the entrance of a cement crusher. Further, in Patent Document 4, when the chlorine concentration brought in becomes higher than the standard value of the cement product, the chlorine compound powder is washed with the water washing treatment equipment 17 to reduce the chlorine content and separated, and then the cement manufacturing apparatus. The method of recovering is described.

  Due to social demands for recycling of waste, with the increase in waste treatment containing a large amount of chlorine, a chlorine bypass with a high bleed rate that can process waste containing even higher concentrations of chlorine compounds than in the past It has been put into practical use. When the amount of extracted powder increases due to an increase in the amount of extraction, the processing method, extraction equipment costs, and the like become problematic. For this reason, it is necessary to reduce the amount of powder by reducing the amount of cement raw material accompanying the extraction gas when extracting, but the concentration of volatile components mainly composed of extracted chlorine compounds is relatively 10%. It is expected that the amount from 20% to 20% by weight will rise to about 50% by weight. This volatile component has a particle size of several to several tens of micrometers, and if these fine powders are mainly used, there is a concern that the handling property is deteriorated.

There are concerns about the following three problems due to the deterioration in handling.
The first problem is that the chlorine compound powder is a fine powder and has a strong adhesion to the powder because it easily absorbs moisture. In particular, a large number of cement raw materials having a comparatively large particle diameter existed in the transport machine 8 in the past, and the raw materials contacted with these raw materials were washed away before the adhesion grew. When the body is transported by the transport aircraft 8, adhesion and aggregation inside the transport aircraft increase.
As a result, there is a concern that the transport capability of the transport aircraft 8 may be reduced, or that the transport aircraft 8 may cause a blockage trouble and cannot be transported. In order to solve this problem, in Patent Document 5, the powder is pressed and then crushed, so that the particle size distribution is shifted to the coarse side to improve the clogging trouble, and the handling of the powder is improved and the handling trouble is improved. Although there is an attempt to eliminate this, there is a problem that this powder is intended for gypsum and a pulverization process is present in the subsequent process, which makes the operation complicated and increases the equipment cost and manufacturing cost.

  Next, as a second problem, when the chlorine compound powder is mixed with the cement clinker and stored, the particle size of the chlorine compound powder is much smaller than that of the cement clinker. It was expected that a segregation phenomenon in which the compounds were unevenly distributed and separated would occur. This means that while extracting the cement clinker from the bottom of the silo from the full amount to the empty amount, the extraction of fine powders containing a large amount of chlorine compounds will vary in time series, leading to unstable chemical composition quality. There was concern. In addition, segregation phenomenon is expected to accelerate due to vibrations in large trailers and tanks of freight cars, or storage tankers for ship transport during large-scale long-distance transportation. It was done.

  Here, FIG. 3 and FIG. 4 show simplified schematic views of the cross section at the time when the tank is full and empty. The segregation phenomenon by the difference in the size of the granular material in a storage tank is demonstrated with this figure. This is a phenomenon in the tank which is a concern when chlorine compound powder is mixed with a cement clinker in large quantities and put into the tank 9.

  FIG. 3 shows a state in which a mixture of cement clinker and powdered chlorine compound is put through the inlet 10 at the upper center of the tank 9 and is almost full. However, the extraction from the extraction port 11 is not performed. The large particle size 12 is unevenly distributed on the inner wall surface of the tank 9. The reason for this is that the clinker in the tank 9 accumulates in a cone-shaped mountain shape with the inlet 10 at the top, and those having a large particle size have large inertial force and kinetic energy, so the mountain-shaped surface is at the bottom. This is due to reaching the side wall surface of the rolling tank 9. The smaller the particle size material 14 is, the more powdery it tends to be accumulated near the top of the mountain shape. As a result, a segregation phenomenon occurs in which the large particle size 12 is deposited on the side wall surface and the small particle size 14 is concentrated on the central portion.

  FIG. 4 shows a cross section immediately before the tank 9 is almost empty. In this case, the fine powder of the small particle size material 14 tends to be unevenly distributed on the surface of the lower cone portion of the tank 9. When the tank 9 in a full state is continuously extracted from the extraction port 11, the surface of the granular material becomes an inverted cone shape in the tank 9. At this time, the larger the particle size, the smaller the angle of repose and the larger the kinetic energy, the more powerfully rolls on the reverse cone-shaped powder fluid surface in the tank, and preferentially comes out of the tank 6. On the other hand, the fine powder of the small particle size material 14 has a large angle of repose in the tank 9 and is difficult to extract, and a portion close to the inner wall surface is selectively used as if sieving the gap between the large particle size materials 12. It sinks downward. For this reason, the fine powder tends to stay in the tank 9, which is a causal factor that the fine powder does not escape unless the tank 9 is close to the empty amount.

The third problem is that, when a large amount of chlorine compound powder is transported over a long distance, the powder is small in volume and contains a lot of air, so that the bulk is large and the transport efficiency is poor.
Japanese Patent Laid-Open No. 10-330136 JP 11-035354 A JP 2000-226241 A Japanese Patent Laid-Open No. 11-100343 JP 2007-136297 A

  The present invention provides a handling property for a powder whose main chemical component is a chlorine compound as a powder extracted in large quantities by a high chlorine bypass device from a high temperature portion such as a kiln bottom 3 or a rising duct 4 of a cement manufacturing apparatus. It is an object of the present invention to provide a method for improving, preventing adhesion and aggregation in transportation, improving transportation efficiency, and avoiding a segregation phenomenon in a mixed storage with a cement clinker.

  The present invention, after extracting the gas containing chlorine compound-containing powder from the kiln bottom of the cement manufacturing apparatus, cooling the gas containing the extracted chlorine compound-containing powder, then separating the chlorine compound-containing powder and gas, A method for treating a chlorine compound-containing powder, comprising granulating the separated chlorine compound-containing powder. The chlorine compound-containing powder is preferably granulated so that the average particle size is 10 to 30 mm. Further, the granulated product can be mixed with the cement clinker at the exit of the clinker cooler of the cement manufacturing apparatus.

  According to the present invention, the handling properties of chlorine compounds extracted in large quantities from a cement production apparatus are improved, and there are no troubles of adhesion to a transporting machine, and a large amount can be transported. Also, uneven distribution and separation due to segregation phenomenon when mixed and stored with cement clinker in a silo or tank can be reduced.

FIG. 1 shows a cement clinker manufacturing apparatus equipped with a gas bleeder as an embodiment of the present invention.
Extraction is performed by an extraction cooling device 5 attached in the vicinity of the kiln bottom 3 within a range of 2 to 10% by volume of the kiln exhaust gas flowing from the cement kiln 1 to the kiln bottom 3. The extraction gas is 1000 to 1200 ° C. at the inlet of the extraction cooling device 5. The extracted gas contains volatile components mainly composed of a solid cement raw material and a gaseous chlorine compound. As volatile components, in addition to chlorine, SO3, K2O and other components are included. The concentration of the volatile component is 8 to 40% by weight in terms of extracted dust powder, and the chlorine compound in the volatile component is 10 to 40% by weight.
Volatile components are rapidly cooled and solidified to 300 to 400 ° C. by the air supplied to the extraction cooling device 5. The rapid cooling rate is about 400 to 900 ° C./second. The chlorine compound-containing powder is separated and collected by a dust collector 6 such as a bag filter.

  Next, the collected chlorine compound-containing powder is granulated by the granulator 16. Here, granulation refers to forming a powder, and is a method of integrating powder particles into a spherical shape by means of mechanical pressure applied from the outside, or a method of integrating powder particles into a sphere with an adhesion medium liquid or the like. It is a concept including a method of dynamic aggregation and integration. Here, a method of integrating the powder particles with a mechanical pressure applied from the outside will be described. As a granulator, a general briquette machine is preferable. Hereinafter, this will be described as a briquette. In addition, it is preferable to granulate the chlorine compound-containing powder so that the average particle size of the briquettes is 10 to 30 mm. This is equivalent to the average particle size of the cement clinker and is considered to be mixed with the cement clinker in the subsequent process. In addition, when the average particle size of the briquette exceeds φ30 mm, the frequency of occurrence of deterioration of formability and briquette cracking increases, and when it is less than φ10 mm, the granulation roll of the granulator is not easily pulled out from the concave hole, Grain efficiency decreases.

The briquette shape may be any other shape such as almond shape, barrel shape, cylindrical shape, spherical shape, square shape, tablet shape, etc., but it must be hard enough to prevent the briquette from being crushed during transportation and storage. . The briquette preferably has a hardness of 3 to 18 kg (measured with a Kiyama hardness tester). If the briquette is too hard, the desalting efficiency in the desalting water washing process described later is poor, and if it is too soft, it becomes fragile during transportation and storage, so it is important to maintain the optimum hardness. The pressure applied by the biaxial rotating roll of the briquette machine is preferably about 50 to 80 kg / cm ² . If it is less than 50 kg / cm ^2, to easily crack briquettes, briquettes exceeds 80 Kg / cm ² is, granulation becomes bad granulation efficiency loss from the recess hole roll granulator decreases. Spraying the release agent onto the granulation roll makes it easier to escape from the concave hole, but at the same time as increasing the manufacturing cost, the release agent components are mixed into the briquette, which is not desirable in terms of product quality in the subsequent steps. Therefore, care must be taken depending on the type of release agent.

  The briquette is returned to the cement manufacturing process via a transport machine (not shown). The return position may be anywhere as long as the volatile components do not vaporize again, but the cement clinker is mixed with the cement clinker at the position of the clinker transport 7 taken out from the clinker cooler 15 of the cement clinker manufacturing apparatus. It is desirable to recover to the manufacturing process. When the chlorine concentration brought into the cement manufacturing apparatus exceeds a quality standard, the chloride is discharged outside the manufacturing apparatus system, so that it is not returned to the cement manufacturing apparatus but transported to the washing treatment facility 17.

  In addition, when storing in a storage silo, tank 9 or the like, it is best to mix the cement clinker and briquette together, put them into the tank 9 and extract the tank 9. Thus, there is no trouble such as adhesion of a transporting machine or the occurrence of segregation phenomenon in the storage silo or the tank 9, and the clinker with little variation in chlorine component exits the tank 9 because it can be uniformly extracted from the storage and transported.

It is also possible to measure the average particle size of the cement clinker and granulate the chlorine compound so as to obtain the same particle size based on the measurement result, thereby forming a briquette shape.
About the average particle diameter and briquette of cement clinker, a particle size distribution is measured about 10 times with a plurality of sieves, and each average particle diameter is calculated. The calculated average particle sizes may be approximately the same size, for example, the difference may be within 30%. If the average particle size of the briquettes is within the standard deviation value range of the cement clinker particle size distribution value, there is no problem in practical use. If it is out of the control range, the leveling operation can be performed by the mixing operation with the extracted amounts of the plurality of silos storing the cement clinker in the subsequent process.

  If the upper limit of 350 ppm of the cement quality regulation value is exceeded due to the amount of volatile components and the chlorine component in the briquette, the briquette of the chlorine compound is transported alone to the water washing treatment facility 17 for water washing treatment. The amount of water required for desalting is 3 to 10 times by weight the briquette chlorine compound. The water tank to be desalted is a tank equipped with a stirrer and needs a size that allows the briquette residence time to be 40 to 90 minutes.

  In this method of improving handling by briquetting, a part of the pre-process of the cement manufacturing process is geographically in the mountainous area, and the post-process of the cement manufacturing process is a seaside factory. This is particularly effective when transporting.

  As described above, the method for treating a chlorine compound-containing powder has been described, but the present invention is particularly useful when chlorine is extracted efficiently as follows. When the chlorine bypass device for exhaust gas from the cement kiln 1 as shown in FIG. 1 is used, most of the volatile components mainly composed of chlorine compounds in the kiln exhaust gas flowing from the cement kiln 1 to the preheater 2 are in the gas phase. A gas having a high volatile component concentration is obtained by selectively extracting only this gas. In other words, by extracting from the portion of the cement raw material having a low concentration contained in the kiln exhaust gas, the entrainment amount of the cement raw material is reduced, and the heat loss due to this is reduced, which is efficient.

  Specifically, when the cement kiln 1 and the preheater 2 of the cement clinker manufacturing apparatus in FIG. 1 are bent upward, the kiln exhaust gas flow drifts and rides on the air flow of the kiln exhaust gas flowing from the cement kiln 1 to the preheater 2. A relatively low part of the cement raw material concentration that returns is generated. If this part is selected and an extraction position is provided, it is possible to extract a floating gas having a low concentration of cement raw material.

  In FIG. 5, the position of the extraction cooling device 5 for selectively extracting only the gas having a relatively low cement raw material concentration is located near the connection portion with the rising duct 4 at the upper portion of the kiln bottom portion 3. Is done. In the cross section of the rising duct 4, the extraction cooling device 5 is attached to a position where air is extracted from the side surface in the same direction as the cement kiln 1 or from the side surface in the direction perpendicular to the cement kiln 1. On the side surface in the same direction as the cement kiln 1, air is extracted from either the center or both ends. On the side surface perpendicular to the cement kiln 1, it is desirable to extract air from a position as close as possible to the cement kiln 1, and the height of the extraction position is preferably as close as possible to the cement kiln 1. The bleed air cooling device 5 is installed with an angle in the upward direction from 0 to 45 degrees from the horizontal, but is preferably a horizontal angle. The mounting direction of the extraction cooling device 5 in the kiln bottom 3 is generally preferably on the same side connected to the cement kiln 1, the concentration of the floating cement raw material is relatively small, and the cement raw material is difficult to accompany. In selecting each of these positions, the optimum position varies depending on the size of each cement kiln, the type of raw fuel, the shape of the duct at the extraction position, etc., so it is determined as appropriate by actually measuring the chlorine concentration in the extraction gas. Is done.

(Measurement method of chlorine concentration)
After making the bead shape with an automatic melter, the chlorine component is automatically measured with an X-ray fluorescence analyzer.

(Measuring method of weight)
The sample powder is naturally dropped from a fixed height of 30 cm onto a self-made iron cylindrical bowl having a volume of 1 liter, and the bowl is piled up. Then, the upper surface of the ridge is cut with a plate. Measure the weight of the basket with a scale. After repeating about 10 times with another sample, the average weight is calculated by average calculation. The briquette is carried out in the same way.

(Measurement method of repose angle)
From a fixed height of 30 cm on the horizontal plane, it gently falls naturally to make a conical mound. When the radius or height of the mound reaches about 20 cm, the test powder is stopped from falling. Measure the inclination angle at six or more locations with a compass that measures the angle of repose. After performing 10 samples and averaging, the angle of repose is calculated.

The powder extracted from the chlorine bypass device of cement kiln 1 was granulated with a granulator.
The collected powder from the chlorine bypass used in the experiment is a powder obtained under the following extraction and quenching conditions. The extraction position is the position and direction of the thick arrow in FIG. In the vicinity of the connecting portion between the kiln bottom 3 and the rising duct 4, air is extracted from the right side wall position in the same direction as the cement kiln 1 with an upward inclination angle of 45 degrees.
The inlet extraction conditions of the extraction cooling device 5 were a gas temperature of 1250 ° C. and an extraction air volume of 674 m ³ / min. The blowing cooling gas conditions to the extraction cooling device 5 were an air temperature of 28 ° C. and a blowing air volume of 2902 m ³ / min. Further, the exhaust gas state at the outlet of the extraction cooling device 5 at this time was a gas temperature of 312 ° C. and an air volume of 3576 m ³ / min. The chloride dust powder collected by the dust collector 6 averaged 42 kg / hr, and the chlorine component concentration was 16% by weight. The weight is 0.34 t / m ³ and the angle of repose is 45 to 48 degrees.
Next, granulation was performed according to the following method. The granulator used in the experiment was manufactured by Otsuka Tekko Co., Ltd. (model number: K-209), with a capacity of 0.8 t / hr, a rotary roll pressing force of 50 to 80 kg / cm ² , and a briquette particle size. Used was an almond shape having a diameter of φ14 mm × thickness of about 9 mm.

The weight of the briquette after granulating the chlorine dust powder was 0.85 t / m ³ , which was approximately tripled. The briquette hardness was about 3 to 18 kg as measured with a Kiyama hardness tester. The angle of repose of this briquette was 34 to 37 degrees after briquetting. The angle of repose is one important index as an index of handling properties such as fluidity of the powder and granular material, and the smaller the angle from the horizontal, the better the fluidity. The measurement value of the angle of repose of a general cement clinker has an average of about 33 degrees, and it can be estimated that this briquette has substantially the same fluidity as the clinker. By briquetting the collected powder of the chlorine bypass, it can be uniformly mixed with the cement clinker. Moreover, since the briquettes of chlorine compounds are difficult to disintegrate, it can be estimated that the adhesion of powder to equipment such as transportation equipment can be greatly reduced, and it can be expected that the trouble of transportation of chlorine compounds will be greatly improved. It was found from the basic experiment that the angle of repose is reduced by briquetting, and as a result, the handling property of the chlorine compound is improved.

Next, a briquette of a chlorine compound having a chlorine component of 16% by weight and a powder product in which the extracted dust was not briquetted were each washed with water, and the solubility of chloride in water was compared in a basic experiment. Water was poured into a polyethylene container (inner dimensions φ160 mm, height 220 mm) to a depth of 110 mm, and briquettes and powder products were introduced so that the water ratio (weight basis) was 5.0. A Teflon (registered trademark) stirring blade (rotating diameter 120 mm × height 25 mm × thickness 3 mm) was set at a position 30 mm from the bottom of the container, and stirred at a rotational speed of 120 rpm for 60 minutes. As a result, the briquette completely disintegrated in water and slurried. As a result of filtering the dissolved slurry and measuring the chlorine content in the filtrate, it is clear that both the briquette and the powder product have the same chlorine component value at 3.3% by weight, and the briquette is desalted in the same manner as the powder product. became. The chlorine content of the solid matter on the filter paper was 1.4% by weight for briquettes and 1.3% by weight for powder products.
Therefore, in terms of the desalting rate, the briquette was 91.3%, which was almost the same as the powder product 91.9. As a result, it was revealed that even a briquette can be desalted satisfactorily.

  By applying the present invention as described above, a further large amount of chlorine-containing waste can be used in the cement manufacturing apparatus, which can greatly contribute to social demands for environmental problems that are further increasing.

  The present invention can be applied by a method using a means of granulation when mixing fine powder and coarse particles uniformly in all industries that handle powder particles. In a narrow sense, when mixing and transporting fine powders other than chlorine compounds with coarse particles in the cement industry, and when efficiently transporting and storing fine and highly adherent powders, Its application is possible.

It is the schematic in the processing method of the powder containing the chlorine compound of this invention. It is the schematic in the processing method of the powder containing the conventional chlorine compound. This is an example of a storage silo segregation phenomenon, in a full state. This is an example of a storage silo segregation phenomenon, which is in a state immediately before the empty amount. It is a figure which shows the attachment position of the extraction cooling device in a kiln bottom part.

Explanation of symbols

1 Cement kiln
2 Pre-heater 3 Kiln bottom 4 Rising duct
5 Extraction cooling device
6 Dust collector
7 Clinker transport
8 Chlorine compound transportation 9 Tank 10 Input port 11 Extraction port 12 Large particle size 13 Large and small mixed particle size 14 Small particle size 15 Clinker cooler 16 Granulator 17 Flushing treatment device

Claims (2)

A gas containing chlorine compound-containing powder is extracted from the kiln bottom of the cement manufacturing apparatus, and after cooling the gas containing the extracted chlorine compound-containing powder, the chlorine compound-containing powder and gas are separated, and the separated chlorine compound A method for treating a chlorine compound-containing powder , comprising granulating the containing powder so as to have an average particle diameter of 10 to 30 mm .   The method for treating a chlorine compound-containing powder according to claim 1, wherein the granulated product is mixed with a cement clinker at a clinker cooler outlet of a cement manufacturing apparatus.

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