JP5772576B2 - Cement raw material processing method and cement raw material manufacturing apparatus for sludge generated in polycrystalline silicon manufacturing process - Google Patents

Description

  The present invention relates to a cement raw material processing method and a cement raw material manufacturing apparatus for reusing sludge generated in a polycrystalline silicon manufacturing process as a cement raw material.

  In the polycrystalline silicon production process, high-purity chlorosilane and high-purity silicon are produced by distillation and purification of chlorosilanes using metal silicon as a starting material. On the other hand, in the production process, metal chloride and By-products such as chlorosilane-based polymers having a relatively high boiling point are also formed, and methods such as recovering useful substances have been performed. However, residues that are ultimately difficult to use are discarded (Patent Document 1). When such a residue is subjected to a treatment such as hydrolysis or a neutralization treatment for safe treatment, a large amount of sludge is produced. For this reason, as one of the methods of using these sludges, using sludge as a part of cement raw material is examined.

However, as described above, the residue generated in the polycrystalline silicon manufacturing process contains a chlorosilane-based polymer and the like, and therefore contains a large amount of chlorine compounds generated in the processing process. If such a material containing a lot of chlorine compounds is used as a cement raw material, it will cause clogging due to the concentration of the raw material in the preheater used in the cement raw material manufacturing process. Thus, a recovery process of a chlorine compound contained in the residue is performed (Patent Document 2).
In addition, in Patent Document 2, water to the extent that waste (residue) is fluidized is added and suspended in a stirring tank to elute chlorine in the waste. It is described that a desalted cake is produced by filtering in a press and the desalted cake is used as a cement raw material.
Eco-cement, which is produced mainly from incineration ash of municipal waste and sewage sludge, is increasingly used as a technology for recycling waste in recent years, and is regulated by Japanese Industrial Standards (JIS). 0.035% or less is determined. However, since chlorine ions contained in the raw material lead to corrosion of reinforcing bars, it is desirable to keep them as low as possible.
Thus, even when sludge obtained by water-treating a chlorosilane-based polymer or the like is used as a cement raw material, a large amount of chlorine components are contained in the sludge by hydrolysis during the treatment process, and thus it is necessary to reduce this. Moreover, it has been confirmed from the results of component analysis that many of the chlorine components contained in the sludge are present as aqueous chloride solutions such as sodium chloride.

JP-A-62-277193 Japanese Patent No. 4210456

  However, in the residue generated in the polycrystalline silicon manufacturing process, in addition to the chlorosilane polymer, by-products generated in the manufacturing process such as metal chloride and polycrystalline silicon fine powder, cutting powder during processing of polycrystalline silicon, etc. In some cases, it is easy to form a lump-like solid, and therefore, the chlorine component cannot be sufficiently reduced by simply stirring and filtering sludge generated in the subsequent treatment as in Patent Document 2.

  The present invention has been made in view of such circumstances, and sufficiently reduces the chlorine component contained in the sludge generated in the polycrystalline silicon manufacturing process, and recycles it as a cement raw material. An object of the present invention is to provide a cement raw material manufacturing apparatus.

  The present invention is a cement raw material processing method for producing a cement raw material by reducing the chlorine component contained in the sludge generated in the polycrystalline silicon manufacturing process, wherein the sludge and Stirring step of forming a slurry state by stirring water, and a crushing step of taking out the solid matter contained in the sludge accumulated in the stirring vessel, crushing the solid matter and throwing it into the stirring vessel And a dehydration step of producing a cement raw material by dehydrating the slurry to remove moisture.

Slurry and water are fluidized by stirring to form a slurry state, so that the chlorine component contained in the sludge can be efficiently eluted, and the large solid contained in the sludge deposited at the bottom of the stirring tank The product is taken out, the solid material is crushed to reduce the diameter, and then returned to the stirring step to facilitate the elution of the chlorine component, thereby improving the cleaning efficiency.
In addition, as described above, when the sludge contains polycrystalline silicon cutting powder during processing of polycrystalline silicon, hydrogen is generated when the polycrystalline silicon cutting powder comes into contact with water during stirring, but the stirring tank is opened. Since it provided in the state, it can prevent that the hydrogen concentration in the tank in stirring becomes high. Furthermore, by combining the stirring step and the crushing step, the polycrystalline silicon cutting powder contained in the solid matter in the sludge can be efficiently contacted with water. Therefore, it is possible to prevent the hydrogen concentration from increasing in the stirring tank and the process system, and to prevent troubles such as hydrogen explosion from occurring.

  The cement raw material production apparatus of the present invention is an apparatus for producing a cement raw material by reducing the chlorine component contained in the sludge generated in the polycrystalline silicon production process, and the slurry is stirred by stirring the sludge and water. Forming the state, the stirring tank with the top opened, the solid contained in the sludge accumulated at the bottom of the stirring tank, and a crusher for crushing the solid, and extracted from the crusher It is characterized by comprising a circulation pipe for introducing a processed product into the stirring tank and a dehydrator for producing a cement raw material by dehydrating the slurry to remove moisture.

  According to the present invention, sludge and water are fluidized by stirring, and after making into a slurry state, solid matter contained in the sludge in the slurry state is taken out and crushed, and returned to the stirring step. Therefore, clogging of the crusher and the like can be prevented, and the chlorine component can be sufficiently reduced from the solid material having a reduced diameter. Moreover, in the sludge containing polycrystalline silicon cutting powder, the hydrogen generated when the polycrystalline silicon cutting powder contained in the sludge comes into contact with water can be removed by stirring in an open stirring tank. Therefore, it is possible to prevent the hydrogen concentration from increasing in the stirring tank and the process system.

It is the schematic which shows the cement raw material manufacturing apparatus of embodiment of this invention. It is the schematic explaining the stirring tank shown in FIG. 1, (a) is a sectional side view, (b) is a top view. It is a figure explaining the crusher shown in FIG.

Hereinafter, an embodiment of the cement raw material treatment method of the present invention will be described.
FIG. 1 shows an overall schematic configuration of a cement raw material manufacturing apparatus. The cement raw material manufacturing apparatus 100 stirs sludge and water to form a slurry state in which a chlorine component contained in the sludge is eluted, and in the sludge accumulated in the lower portion of the stirring tank 10. The contained solid matter is taken out, the crusher 20 for crushing the solid matter, the storage container 21 to which the processed product after pulverization is sent, and the treated product is taken out from the storage container 21 and introduced again into the stirring tank 10. A circulation pipe 22, a water tank 30 for diluting and washing the slurry discharged from the stirring tank 10, and a dehydrator 40 for producing a cement raw material by dehydrating the slurry that has passed through the water tank 30 to remove moisture. It has.

The sludge supplied to the agitation tank 10 is obtained by solidifying the sludge generated in the polycrystalline silicon manufacturing process by removing moisture with a dehydrator or the like. The sludge contains chlorine components (chlorine ions). There are many.
As shown in FIG. 2, the agitation tank 10 is composed of a container 13 whose upper part is open and a stirrer 15 having rotating blades. Sludge and water (for example, industrial water) are placed in the container 13. By putting them in and stirring them with the stirrer 15, the chlorine component contained in the sludge can be eluted to form a slurry state.
Further, the container 13 is provided with two rows of three baffle plates 14 at intervals of 180 ° in the depth direction. By arranging the baffle plate 14 in this way, the swirl flow generated by the rotating blades of the stirrer 15 can be controlled, and the vertical circulation flow and the lower radiation flow can be formed. Thereby, sludge and water can be efficiently stirred in the tank.
The height h of the baffle plate 14 from the side surface of the container is set to about 7/100 to 1/5 with respect to the inner peripheral diameter D of the container 13, resulting in fine particles and dispersion of solid matter. It is easy to make it. Further, a gap s is provided between the baffle plate 14 disposed at the lowermost position and the bottom surface of the container 13 to prevent sludge from accumulating at the lower part of the container 13. When the gap s is narrow, not only the sludge accumulates, but also solid matter in the sludge at the bottom of the container 13 is likely to aggregate when being stirred in the container 13 by the swirling flow, and this may hinder the swirling flow. Become. In addition, if the gap s is wide, the solid matter in the sludge at the bottom of the container 13 is less likely to collide with the baffle plate 14, and the crushing of the solid matter is not promoted, so that processing time is required. For this reason, the interval s is desirably set to 20 mm or more, and more desirably to approximately 30 mm to 70 mm.
The discharge port 12a for sending the slurry to the water tank 30 is provided above the inner bottom surface of the container 13 by 0.03 times or more of the water level charged into the container 13, and the slurry discharged from the discharge port 12a. In addition, a large solid material is not included. When the position of the discharge port 12a is low, a large solid may enter the discharge port 12a, and the discharge port 12a is blocked to prevent the slurry from being discharged, so that the slurry cannot be discharged stably. Further, when the discharge port 12a is at a higher position than the bottom surface of the container 13, the slurry having a relatively small particle size in the sludge is discharged preferentially. Are likely to gather, and variations in chlorine components are likely to occur within the container 13. Therefore, the height of the discharge port 12a from the bottom surface of the container 13 is desirably up to 0.2 times the water level charged into the container 13.

As shown in FIG. 3, the crusher 20 includes a rotating blade 26 that is rotated by a rotor 25, and a fixed blade 27 that is disposed between the rotating blades 26. The solids contained in the sludge supplied from the upper part of the crusher 20 are crushed by these blades 26 and 27 to reduce the diameter.
The blades 26 and 27 are arranged at intervals, and the solid matter contained in the sludge taken out from the stirring tank 10 can be crushed to a size of, for example, several mm or less. In this case, it is easy to elute the chlorine component by finely crushing the solid, and the cleaning efficiency can be improved.
It should be noted that the finer the solid matter, the easier it is to elute the chlorine component and the better the sludge cleaning efficiency. It takes longer time to crush. Therefore, the size of the solid material crushing may be appropriately set depending on the required cleaning efficiency and time.
Then, the crushed processed product (mixture of slurry and crushed material) extracted from the lower part of the pulverizer 20 is sent to the open storage container 21, and is fed to the agitation tank 10 through the circulation pipe 22 by the pump 23. Returned.

  The water tank 30 dilutes and wash | cleans the slurry containing the chlorine component eluted from the sludge discharged | emitted from the stirring tank 10 with water. In addition, industrial water is supplied to the water tank 30 from a water tank 50 arranged on the upstream side of the stirring tank 10, and the slurry is diluted and washed with this industrial water. Industrial water is water having a sufficiently lower chloride ion concentration than sludge. For example, the chlorine ion concentration of sludge is 5000 ppm to 20000 ppm, whereas the chlorine ion concentration of industrial water is 5 ppm to 850 ppm.

The dehydrator 40 manufactures a dehydrated cake by removing moisture from the slurry that has been diluted and washed through the water tank 30, and a filter press, for example, can be used.
In addition, the codes | symbols 11 and 12 shown in FIG.1 and FIG.2 are the opening / closing valves provided in piping.

Next, a method for manufacturing a cement raw material using the cement raw material manufacturing apparatus 100 will be described.
In the cement raw material manufacturing apparatus 100 shown in FIG. 1, sludge is introduced into the container 13 of the stirring tank 10, and industrial water is supplied from the water tank 50, and the sludge and industrial water are stirred for a predetermined time and fluidized. Then, a stirring cleaning process is performed (stirring step). Then, as shown in FIG. 2, after sludge and industrial water are stirred and fluidized, the valve 11 provided at the lower part of the container 13 is opened, and the sludge accumulated from the outlet 11a is disintegrated. After the solid matter contained in the sludge is crushed, the treated product is returned to the stirring tank 10 and circulated (pulverization step). Thereby, while making the chlorine component contained in sludge easy to elute, hydrogen is generated when polycrystalline silicon cutting powder etc. are contained in a solid. In addition, hydrogen is dissipated from the upper part of the container 13 of the stirring tank 10 provided in the open state.

After the sludge and the industrial water are stirred for about 10 minutes, the valve 12 provided at the lower part of the container 13 of the stirring tank 10 is opened, and the slurry is sent from the discharge port 12a to the water tank 30. At this time, industrial water is supplied from the water tank 50 to the water tank 30. Then, after the slurry and industrial water are mixed and diluted and washed, the diluted and washed slurry is supplied to the dehydrator 40 and dehydrated to remove moisture containing chlorine components to produce a dehydrated cake. (Dehydration process).
The dehydrated cake thus produced has a sufficiently reduced chlorine component and can be used as a part of the cement raw material.

  As described above, in the cement raw material manufacturing apparatus 100 of the present embodiment, sludge and water are stirred and fluidized to elute chlorine components contained in the sludge, and sludge accumulated in the lower portion of the stirring tank 10. By taking out a solid material having a large shape contained therein, pulverizing the solid material to reduce the diameter, and then returning to the stirring step, the chlorine component can be easily eluted, and the cleaning efficiency can be improved.

Further, by crushing a solid material having a large shape after stirring and fluidizing sludge and water, blockage of the crusher and the like can be prevented, and crushing can be efficiently performed.
Furthermore, when the polycrystalline silicon cutting powder at the time of polycrystalline silicon processing is contained in the sludge, hydrogen is generated when the polycrystalline silicon cutting powder and water come into contact with stirring, but the upper part of the stirring tank is provided in an open state. Therefore, it can prevent that the hydrogen concentration in the tank under stirring becomes high. Furthermore, by combining the stirring step and the crushing step, it is possible to efficiently make contact between the polycrystalline silicon cutting powder and the like contained in the solid matter in the sludge and water, and to smoothly remove hydrogen. it can. Therefore, it is possible to prevent the hydrogen concentration from increasing in the stirring tank and each process system, and to prevent troubles such as hydrogen explosion from occurring.

Next, examples of the cement raw material treatment method of the present invention will be described.
Sludge and industrial water having the conditions shown in Table 1 are put into a container of a stirring tank and fluidized by stirring for 10 minutes, and then about 300 liters of sludge accumulated at the bottom of the container is taken out and contained in the sludge. The operation of crushing the solid material and returning it to the stirring tank was performed 7 times. And the sludge of the slurry state after stirring was taken out, the pressure of 0.5 MPaG was applied with the spin-dryer | dehydrator, about 1 hour was driven, the slurry was spin-dry | dehydrated, and the dewatering cake was manufactured. The components of the obtained dehydrated cake and the components of the filtered filtrate are shown in Table 2. In addition, the measurement of the chlorine ion concentration of Table 1 and Table 2 was performed by the ion chromatograph.
And in the crusher used in the present Example, the space | interval of fixed blade | wings and rotary blades was set to 17 mm. Further, the stirring tank uses a container having an inner diameter of 1.26 m, the gap s between the baffle plate disposed at the lowest position in the container and the bottom surface of the container is set to 50 mm, and the discharge port 12a is set in the container. It was arranged 15 cm above the inner bottom surface. And the sludge and industrial water were thrown in to the about 1.4-m water level of the container, and it stirred.

As can be seen from the results in Table 2, the dehydrated cake after treatment has a greatly reduced chlorine ion concentration compared to the sludge before treatment. According to the present invention, the chlorine component contained in the sludge is greatly reduced. It was confirmed that it can be reduced. Moreover, clogging of the crusher and the circulation piping system did not occur.
In samples 4 and 5, industrial water having a higher chlorine ion concentration than the industrial water used in samples 1 to 3 was used, but this industrial water was sufficiently lower than the chlorine ion concentration of the sludge to be introduced. It was found that the chlorine component can be sufficiently reduced even when such industrial water is used. Accordingly, it was found that even when industrial water having a high chlorine ion concentration is used, the chlorine ion concentration can be reduced to a level that can be used for eco-cement and the like.

In addition, this invention is not limited to the thing of the structure of the said embodiment, In a detailed structure, a various change can be added in the range which does not deviate from the meaning of this invention.
In the above embodiment, a certain amount of sludge taken out and crushed is returned to the stirring tank, but these processes are automatically performed while continuously monitoring the slurry in the water tank 30 and the dehydrated cake after dehydration. It is good also as a structure performed continuously.

DESCRIPTION OF SYMBOLS 10 Stirring tank 11,12 Open / close valve 11a Outlet 12a Outlet 13 Container 14 Baffle plate 15 Stirrer 20 Crusher 21 Storage container 22 Circulation pipe 23 Pump 25 Rotor 26 Rotary blade 27 Fixed blade 30, 50 Water tank 40 Dehydrator 100 Cement Raw material production equipment

Claims (2)

  A cement raw material processing method for producing a cement raw material by reducing the chlorine component contained in the sludge generated in the polycrystalline silicon manufacturing process, and stirring the sludge and water in an agitation tank with the upper part opened. A stirring step for forming a slurry state, a solid matter contained in the sludge accumulated in the stirring tank is taken out, the solid matter is crushed, and the slurry is put into the stirring tank; and the slurry And a dehydration step of producing a cement raw material by removing water by dehydrating the cement.   An apparatus for producing a cement raw material by reducing the chlorine component contained in sludge generated in the polycrystalline silicon production process, which forms a slurry state by stirring the sludge and water, the upper part being opened The agitation tank and the solid matter contained in the sludge accumulated at the bottom of the agitation tank are taken out, a pulverizer for crushing the solid substance, and a processed material extracted from the pulverizer is charged into the agitation tank. A cement raw material production apparatus comprising: a circulation pipe; and a dehydrator for producing a cement raw material by dehydrating the slurry to remove moisture.

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