JP2012086161A - Bubbling device and method of treating blast furnace or converter dust collecting water using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bubbling device preventing clogging of injection ports and enabling stable aeration treatment.SOLUTION: The bubbling device includes: a first nozzle member receiving compressed gas and injecting the compressed gas from a first injection port; and a second nozzle member receiving the compressed gas and injecting the compressed gas from a second injection port. The first and second nozzle members are arranged so that the compressed gas is injected from the second injection port to a portion around the first injection port.

Description

  The present invention relates to a bubbling device and a method for treating blast furnace or converter dust collection water using the bubbling device, and more specifically, a bubbling device used for aeration treatment in which gas and liquid are efficiently contacted, and a blast furnace or converter using the bubbling device. The present invention relates to a method for treating dust collection water.

  As a prior art related to this invention, the dust contained in the gas discharged from the blast furnace is collected by a wet dust collector, and the pH is adjusted by adding caustic soda to the collected dust collected dust. After the metal ions such as iron, calcium, and magnesium dissolved in the dust collection water are converted into insoluble hydroxides and precipitated in the dust collection water, a polymer flocculant is added and sludge together with other dusts with a thickener. There is known a method for treating dust collection water in which treated water separated and separated from sludge is reused for dust collection in a wet dust collector (see, for example, Patent Document 1).

  Further, as a prior art related to the present invention, dust contained in gas discharged from a blast furnace or a converter is collected by a wet dust collector, and the collected dust is collected by aeration. After precipitating calcium ions dissolved in the dust water as insoluble calcium carbonate in the dust collection water, a polymer flocculant is added, and the thickener is precipitated as sludge together with other dust, and the treated water separated from the sludge is wet collected. There is known a method for treating dust collection water that is reused for dust collection in a dust container (for example, see Patent Document 2).

JP 49-133209 A JP 2001-70987 A

Gas discharged from blast furnaces used to produce pig iron from iron ore and converters used to produce pig steel by refining pig iron has large thermal energy and is generated by reactions in the furnace. Contains useful gas.
For this reason, the gas discharged from the blast furnace and converter is recovered and reused as a heat source and fuel. However, since it contains a large amount of dust, it is contained in the gas for efficient recovery and reuse. Dust must be removed beforehand.

A wet dust collector is used to remove dust contained in the gas, and a large amount of treated water is sprayed on the gas containing dust to collect the dust in the gas.
Dust collection water that collects dust is treated to remove dust in the circulating water system and then reused for dust collection or treated with water so as not to adversely affect the environment. It is drained at.
However, the dust collection water has a low pH when absorbing carbon dioxide contained in the gas, and the dust collection water having a lowered pH corrodes the circulating water system and has an adverse effect on wastewater treatment. PH adjustment is necessary to cause various problems.

In order to adjust the pH of the dust collection water, a hydroxide compound that exhibits strong basicity in an aqueous solution, such as caustic soda (sodium hydroxide), calcium hydroxide, and magnesium hydroxide, is generally used.
However, if these hydroxide compounds continue to be used for pH adjustment, the salt concentration in the circulating water system of the dust collection water becomes too high and the scale tends to adhere to the circulating water system, so frequent water exchange (drainage and water supply) Necessary.

  In addition, the dust collection water discharged from the converter is colored yellow brown with iron ions, and it is not preferable to discharge the colored dust collection water from the viewpoint of environmental conservation. Need to be removed.

When hydroxide is used to adjust the pH of the dust collection water, the iron ions in the dust collection water change into insoluble iron hydroxide and precipitate in the dust collection water.
However, when such sludge containing iron hydroxide is discharged from thickener, which is a settling tank provided in the circulating water system, and piled outdoors, iron hydroxide reacts with oxygen in the atmosphere and burns violently. It will be dangerous.

Therefore, in the circulating water system of the dust collection water, aeration treatment is performed on the dust collection water to drive out carbon dioxide from the dust collection water to increase the pH or oxidize iron ions in the dust collection water to insoluble iron oxide. Attempts have been made to precipitate in the dust collection water.
The aeration process is performed by installing a bubbling device having a large number of injection ports in a circulating water system and injecting a gas such as air or oxygen from the injection ports in the dust collection water.

However, when the aeration process is performed in the dust collection water, the scale adheres within a short period of time and the injection port is blocked, making it impossible to perform the aeration process.
For this reason, frequent maintenance and replacement of the bubbling device is necessary to perform the aeration process on the collected water, and it has been very difficult to perform a stable aeration process over a long period of time.

  The present invention has been made in view of the above circumstances, and provides a bubbling device that makes it possible to perform stable aeration processing in which an injection port is hardly blocked and a method for treating blast furnace or converter dust collection water using the same. To do.

  The present invention includes a first nozzle member that receives compressed gas and injects it from a first injection port, and a second nozzle member that receives the compressed gas and injects it from a second injection port, and the first and second nozzle members Provides a bubbling device that is arranged so that compressed gas is injected from the second injection port to the periphery of the first injection port.

  According to this invention, since the compressed gas is injected around the first injection port by the second nozzle member, the generation of vortex is suppressed around the first injection port, and the scale hardly adheres to the first injection port. Even if it adheres, it can be mechanically peeled off by the pressure of the compressed gas, and the first injection port can be prevented from being blocked. Thereby, the bubbling apparatus which enables the stable aeration process can be provided.

It is a front view of the bubbling device concerning the embodiment of the present invention. It is a top view of the bubbling apparatus shown by FIG. It is a bottom view of the bubbling apparatus shown by FIG. It is AA arrow sectional drawing of the bubbling apparatus shown by FIG. It is a principal part enlarged view of FIG. It is a top view of a dome shape container simple substance which constitutes a bubbling device concerning an embodiment of the present invention. It is a front view of the joint simple substance which comprises the bubbling apparatus which concerns on embodiment of this invention. FIG. 8 is a bottom view of the joint shown in FIG. 7. It is explanatory drawing which shows typically the circulating water system of the converter dust collection water in which the aeration process which concerns on Example 1 of this invention was implemented.

  A bubbling device according to the present invention includes a first nozzle member that receives a compressed gas and injects the compressed gas from a first injection port, and a second nozzle member that receives the compressed gas and injects the compressed gas from a second injection port. The two-nozzle member is arranged so that compressed gas is injected from the second injection port to the periphery of the first injection port.

In the bubbling apparatus according to the present invention, the compressed gas means all pressurized gases, and the type of gas is not particularly limited.
Therefore, the bubbling device of the present invention can be used for the purpose of efficiently bringing various gases into contact with the liquid, and the aeration treatment is not limited to the contact between water and air but also the contact between various liquids and gases. Including.
The compressed gas preferably contains a small amount of liquid, and the contact efficiency of the gas can be improved by including a small amount of liquid in the compressed gas and injecting it from the first and second injection ports. Furthermore, it is possible to effectively suppress the growth of the scale at the first and second ejection ports by the action of erosion caused by the ejected liquid.

Further, the fact that the compressed gas is injected from the second injection port to the periphery of the first injection port is to cancel the vortex generated around the first injection port in order to prevent the scale from adhering to the first injection port. It means that a compressed gas having a pressure and a flow rate as much as possible is injected from the second injection port toward the periphery of the first injection port without hindering the injection of the first injection port.
Therefore, various conditions such as the distance between the first injection port and the second injection port, the injection angle of the second injection port with respect to the first injection port, and the diameters of the first injection port and the second injection port are as described above. It is adjusted appropriately according to the pressure and flow rate of the compressed gas so as to be effectively played.

In the bubbling device according to the present invention, the first nozzle member may include a pressure accumulating container having a receiving port for receiving compressed gas and the first injection port.
According to such a configuration, since the compressed gas is once accumulated in the pressure accumulating container and then injected through the first injection port, the injection state is stabilized and a good aeration process is possible.

  In the above configuration in which the first nozzle member includes the pressure accumulating container, the pressure accumulating container is composed of a bottom plate member having the receiving port in the center, and a dome-shaped container that is hermetically installed on the bottom plate member, and the second nozzle The member may be provided so as to protrude from the top of the dome-shaped container.

  According to such a configuration, the second nozzle member is provided so as to protrude from the top of the dome-shaped container, so that the compressed gas injected from the second injection port is injected around the first injection port. It becomes easy to arrange | position the 2nd injection port of 2 nozzle members toward the 1st injection port of a 1st nozzle member.

  In the above-described configuration in which the second nozzle member is provided so as to protrude from the top of the dome-shaped container, the first injection port includes a plurality of first through holes formed on a concentric circle centering on the top of the dome-shaped container. The second nozzle member includes a cylindrical body provided in communication with the dome-shaped container, and a lid fitted into the upper end of the cylindrical body, and the second injection port corresponds to the first through hole of the lid. You may consist of several 2nd through-hole formed in the circumference radially.

  According to such a structure, since the 1st injection port consists of several 1st through-holes formed on the concentric circle centering on the top part of a dome shape container, the compressed gas which accumulate | stored in the pressure accumulation container is dome-shaped. It can be uniformly dispersed around the shape container and ejected, and a more efficient aeration process is possible.

  Further, since the second nozzle member is composed of a cylindrical body provided in communication with the dome-shaped container and a lid fitted to the upper end of the cylindrical body, the compressed gas for the pressure accumulating container is supplied to the second nozzle. It can also be supplied to members. For this reason, the supply path of the compressed gas to the first and second nozzle members is common, and there is no need to provide a separate supply path of the compressed gas for the second nozzle member.

  Further, since the second injection port is constituted by a plurality of second through holes formed radially around the lid corresponding to the plurality of first through holes, it is concentric around the top of the dome-shaped container. Compressed gas can be injected from the plurality of second through holes toward the plurality of first through holes formed on the circle, respectively, and scales can be prevented from adhering to the first through holes.

  In the above configuration, in which the second nozzle member includes a cylindrical body provided in communication with the dome-shaped container, and a lid fitted to the upper end of the cylindrical body, the receiving port and the cylindrical body are the dome-shaped container. It may be coaxial with the central axis of the vessel.

  According to such a configuration, since the compressed gas receiving port and the cylindrical body are provided coaxially with the central axis of the dome-shaped container, the compressed gas can be efficiently supplied to the second nozzle member. Thereby, it becomes possible to stably inject the compressed gas from the second through holes toward the periphery of the first through holes, and more reliably prevent the scale from adhering to the first through holes.

Further, in the above configuration in which the pressure accumulating container is composed of the bottom plate member and the dome-shaped container, the surface of the dome-shaped container may be mirror-finished.
According to such a structure, since the surface of a dome shape container becomes smooth, it becomes difficult for a scale to adhere mechanically and it can prevent more effectively that a scale adheres to a 1st injection port.

  From another point of view, the present invention uses the above-described bubbling device according to the present invention to collect oxygen in the collected water in a circulating water system for collecting dust contained in the gas discharged from the blast furnace or converter. The present invention also provides a method for treating blast furnace or converter dust-collected water, characterized in that aeration treatment is performed with a gas containing gas.

According to the above processing method of the present invention, the aeration treatment is performed with the gas containing oxygen on the dust collection water in which the dust is collected. Therefore, the carbon concentration contained in the dust collection water is increased by increasing the oxygen concentration of the dust collection water. It is possible to expel it into the atmosphere and raise the pH of the collected water to such an extent that it does not adversely affect the circulating water system and wastewater treatment.
Further, since the oxygen concentration in the dust collection water is increased, the iron ions contained in the dust collection water can be changed into insoluble iron oxide and deposited in the dust collection water.
As a result, while reducing the amount of hydroxide compounds such as caustic soda, calcium hydroxide and magnesium hydroxide, it is possible to adjust the pH of dust collection water and remove iron ions, and to prevent coloring of dust collection water. The salt concentration in the circulating water system can be kept low.

In addition to preventing dust collection water from being colored, wastewater treatment is facilitated, and by keeping salt concentration low, scales can be prevented from adhering to various facilities in the circulating water system. ) Can be reduced.
Therefore, not only the cost for the operation of the circulating water system of the dust collection water can be suppressed, but also an environmentally friendly operation is possible.
Furthermore, since the amount of iron hydroxide contained in the sludge is reduced, it is possible to prevent a dangerous situation in which the piled sludge reacts with oxygen in the atmosphere and burns violently to generate heat.

In the above blast furnace or converter dust collection water treatment method according to the present invention, the gas containing oxygen may be air.
By using air, the cost required for the aeration process can be reduced as compared with the case of using a special gas such as pure oxygen or nitrogen.
In particular, when the dust collection water is blast furnace dust collection water, the concentration of iron ions contained in the dust collection water is low compared to the converter dust collection water and no coloring occurs. If the pH can be increased, the purpose of the aeration treatment is achieved.
For this reason, the method using air is particularly useful when the dust collection water is blast furnace dust collection water.

In the above blast furnace or converter dust collection water treatment method according to the present invention, the gas containing oxygen may be pure oxygen.
By using pure oxygen, it is possible to quickly increase the oxygen concentration of the dust collection water, promote the oxidation reaction of iron ions, and collect the iron ions contained in the dust collection water as insoluble iron oxide with considerable certainty. It can be deposited in dust water.
In particular, when the dust collection water is converter dust collection water, the concentration of iron ions contained in the dust collection water is higher than that in the blast furnace dust collection water, resulting in coloration. It is preferable for removing iron ions from the collected water to remove coloration.

In the blast furnace or converter dust collection water treatment method according to the present invention, the circulating water system includes a thickener for precipitating dust contained in the dust collection water, and the aeration treatment is performed before the dust collection water flows into the thickener. Preferably it is done.
This is because the aeration treatment is performed before the dust collection water flows into the thickener, so that when the dust collection water flows into the thickener, iron ions in the dust collection water are changed into insoluble iron oxide and deposited. This is because iron oxide can be rapidly precipitated with a thickener.
In thickeners, a polymer flocculant can be used to precipitate iron oxide and other dusts efficiently.

In the above configuration in which the aeration treatment is performed before the dust collection water flows into the thickener, the circulating water system has a conditioner tank for removing heavy dust with a large particle size in advance before the dust collection water flows into the thickener. In preparation for the upstream side, the aeration process may be performed in the conditioner tank.
By performing the aeration process in the conditioner tank, a sufficient contact time between the gas sprayed from the bubbling device and the dust collection water can be secured, and the aeration process can be performed efficiently.

  Hereinafter, a bubbling device according to an embodiment of the present invention will be described with reference to the drawings.

  A bubbling device according to an embodiment of the present invention will be described with reference to FIGS. 1 is a front view of a bubbling device according to an embodiment of the present invention, FIG. 2 is a plan view of the bubbling device shown in FIG. 1, FIG. 3 is a bottom view of the bubbling device shown in FIG. FIG. 5 is an enlarged view of a main part of FIG. 4, FIG. 6 is a plan view of a single dome-shaped container constituting a bubbling device according to an embodiment of the present invention, and FIG. 7 is an embodiment of the present invention. FIG. 8 is a bottom view of the joint shown in FIG. 7. FIG. 8 is a front view of the joint constituting the bubbling apparatus according to FIG.

  As shown in FIGS. 1 to 4, the bubbling device 1 according to the embodiment of the present invention receives the compressed gas and injects the compressed gas from the first injection port 3, and receives the compressed gas and receives the second gas. A second nozzle member 4 that injects from the injection port 5, and the first and second nozzle members 2, 4 are arranged such that compressed gas is injected from the second injection port 5 to the periphery of the first injection port 3. ing.

As shown in FIGS. 1 and 4, the first nozzle member 2 includes a pressure accumulating container 7 having a receiving port 6 that receives compressed gas and a first injection port 3. The pressure accumulating container 7 is composed of a bottom plate member 8 having a receiving port 6 in the center and a dome-shaped container 9 having a predetermined height H1 that is hermetically installed on the bottom plate member 8.
The bottom plate member 8 and the dome-shaped container 9 are both made of stainless steel (SUS316), and the surface of the dome-shaped container 9 is chrome plated. In addition, it may be mirror-finished instead of chrome plating.

  1 and 2, the first injection port 3 has a predetermined diameter D4 (FIG. 5) formed on the concentric circles 11a, 11b, and 11c of the circular top portion 9a of the dome-shaped container 9. And 30 first through holes 10 having a reference).

  Specifically, as shown in FIGS. 1 and 2, flanges 9d (FIGS. 4 and 6) of the dome-shaped container 9 have different diameters D1, D2, and D3 around the center of the top portion 9a of the dome-shaped container 9. Three concentric circles 11a, 11b, and 11c each having a predetermined height H2, H3, and H4 are set, and ten first through holes 10 are formed on each concentric circle 11a, 11b, and 11c. Are formed at equal intervals.

  The first through holes 10 formed on the concentric circles 11 a, 11 b, and 11 c are arranged radially from the center of the top portion 9 a of the dome-shaped container 9. That is, as shown in FIG. 2, the first through holes 10 formed on the concentric circles 11 a, 11 b, and 11 c are arranged in a straight line outward from the center of the top portion 9 a of the dome-shaped container 9. Are arranged in a row.

On the other hand, as shown in FIGS. 1 and 4, the second nozzle member 4 is provided so as to protrude upward from the top 9 a of the dome-shaped container 9.
The second nozzle member 4 includes a stainless steel cylindrical body 12 provided in communication with the dome-shaped container 9 and a stainless steel lid 13 fitted to the upper end of the cylindrical body 12. The second injection port 5 is composed of ten second through holes 14 having a predetermined diameter D5 (see FIG. 5) formed radially around the lid 13 corresponding to the arrangement of the first through holes 10. Has been.

That is, as shown in FIG. 2, the second through holes 14 are formed at equal intervals around the lid 13 so as to coincide with the arrangement of the first through holes 10 arranged radially from the center of the top portion 9a. Yes.
Further, as shown in FIG. 5, each second through hole 14 is formed to be directed downward by a predetermined angle θ from the horizontal direction so that compressed gas can be injected toward the periphery of the first through hole 10. ing.

  As shown in FIGS. 1 and 4, the cylindrical body 12 is a hollow pipe in which a male screw is formed on the outer surface and a nut-like flange portion 12 a is formed at an equal distance from both ends. And is attached to the dome-shaped container 9 via the joint 15 and the first packing ring 16 so as to be coaxial with the receiving port 6.

Specifically, as shown in FIGS. 5, 7, and 8, the joint 15 is a cylindrical body in which a female screw is formed on the inner periphery and a male screw is formed on the outer periphery, and a flange portion 15 a is formed on one end. Yes.
As shown in FIGS. 7 and 8, a positioning projection 15 b is formed on the flange portion 15 a of the joint 15 on the surface facing the dome-shaped container 9.
On the other hand, as shown in FIG. 6, a cutout 9 c that engages with the protrusion 15 b of the joint 15 is formed in the upper opening 9 b of the dome-shaped container 9.

As shown in FIG. 5, the joint 15 is inserted into the upper opening 9 b of the dome-shaped container 9 through the first packing ring 16 so that the protrusion 15 b of the flange portion 15 a fits into the notch 9 c of the dome-shaped container 9. The flange nut 18 is fixed from the inside of the dome-shaped container 9 through the second packing ring 17.
The cylindrical body 12 is screwed into the joint 15 until the flange portion 12a contacts the flange portion 15a of the joint 15.

  As shown in FIGS. 1 and 5, a lid 13 is attached to the upper end of the cylindrical body 12 provided so as to protrude from the dome-shaped container 9. As shown in FIG. 1 and FIG. 5, the lid 13 has a nut shape with a nut-like flange portion 13 a formed on the lower end side of the outer periphery and a female nut formed on the inner periphery, and is formed on the outer periphery of the cylindrical body 12. It is mounted by screwing with a male screw.

As shown in FIG. 5, when the lid 13 is mounted, on the concentric circles 11a, 11b, 11c (see FIGS. 1 and 2) on the extension line of the second through hole 14 directed downward by a predetermined angle θ. The height H5 of the second through hole 14 with respect to the top portion 9a of the dome-shaped container 9 must be adjusted so that the first through hole 10 formed in the above is located.
As shown in FIG. 2, the lid 13 has a cylindrical shape so that the second through holes 14 coincide with the arrangement of the first through holes 10 that are arranged radially from the center of the top portion 9 a of the dome-shaped container 9. Must be fixed relative to the body 12.

  Therefore, in this embodiment, the height H5 of the second through hole 14 with respect to the top 9a of the dome-shaped container 9 (see FIG. 5) is appropriate, and the second through hole 14 matches the arrangement of the first through holes 10. The lid 13 with respect to the cylindrical body 12 is fastened to each other at an appropriate position by a locking nut 19 and a flange portion 13a of the lid 13 which are screwed in advance on the outer periphery of the cylindrical body 12 so that the lid 13 is fixed at the position. Is positioned.

The dome-shaped container 9 to which the second nozzle member 4 is mounted in this manner is fixed on the bottom plate member 8 by bolts 21 and nuts 22 via rubber packings 20 as shown in FIGS. Yes.
Specifically, as shown in FIG. 4, the packing 20 is formed with a through hole 20a having the same shape as the receiving port 6, and the dome-shaped container 9 is formed with a flange portion 9d whose outer periphery is bent outward. ing.

The packing 20 is placed on the bottom plate member 8 so that the receiving port 6 of the bottom plate member 8 and the through hole 20a of the packing 20 coincide with each other, and the dome on the packing 20 so that the packing 20 and the flange portion 9d abut. A shaped container 9 is placed.
The flange portion 9 d of the dome-shaped container 9 is covered with a stainless retaining ring 23 so as to press the dome-shaped container 9 against the packing 20.

Through holes (not shown) for passing bolts 21 are formed in the holding ring 23, the packing 20 and the bottom plate member 8, respectively, the bolts 21 are passed from the holding ring 23 side, and nuts from the bottom plate member 8 side. 22 is fixed.
In this way, the flange portion 9d formed on the periphery of the dome-shaped container 9 is sandwiched between the pressing ring 23 and the packing 20, and the dome-shaped container 9 is hermetically installed on the bottom plate member 8. Yes.

In the present embodiment, the number of the first through holes 10 constituting the first injection ports 3 is 30 and the number of the second through holes 14 constituting the second injection ports 5 is 10, but the first The number of the through holes 10 and the second through holes 14 is not limited to this, and can be variously changed according to the purpose.
Specifically, in the present embodiment, the number of the first through holes 10 and the second through holes 14 can be set as follows, for example.

Number of first through holes 10 constituting the first injection port 3: n1 = p × q
Number of second through holes 14 constituting the second injection port 5: n2 = q
Here, p is the number of concentric circles centered on the center of the top portion 9a of the dome-shaped container 9, and q is the number of first through holes formed on each concentric circle.
That is, in the present embodiment, the number of second through holes 5 matches the number of first through holes 10 formed on each concentric circle.

Example 1
As Example 1, a bubbling device having a configuration substantially similar to that of the bubbling device 1 shown in FIGS. 1 to 5 was installed in a circulating water system of converter dust collection water, and aeration processing was performed on the dust collection water.

  The outline of the circulating water system of the converter dust collection water will be described with reference to FIG. FIG. 9 is an explanatory view schematically showing a circulating water system of converter dust-collected water subjected to the aeration process according to the first embodiment.

As shown in FIG. 9, the gas discharged from the converter 30 is sent through a primary dust collector 31 and a secondary dust collector 32 to a recovery device (not shown).
In the primary and secondary dust collectors 31 and 32, a large amount of treated water is blown to remove a large amount of dust contained in the gas, and the dust contained in the gas is collected in the treated water.
Specifically, treated water is supplied from the treated water tank 39 of the circulating water system to the secondary dust collector 32 by the pump 40, and dust is collected. The collected water from which the dust is collected by the secondary dust collector 32 is then supplied to the primary dust collector 31 by the pump 41 to further collect the dust.

  Dust collected from the dust collected by the primary and secondary dust collectors 31 and 32 is greatly reduced in pH due to carbonic acid contained in the gas, and contains a large amount of iron ions that cause coloring of the collected dust. It flows into the 1st conditioner tank 33 in the state containing.

In the first conditioner tank 33, heavy dust particles having a large particle size contained in the collected dust water are naturally settled, and the collected dust water overflowed from the first conditioner tank 33 flows into the second conditioner tank 34.
In the 2nd conditioner tank 34, the dust which was not able to be removed in the 1st conditioner tank 33 is removed by natural sedimentation.
In addition, the dust collected in the bottom of the 1st and 2nd conditioner tanks 33 and 34 is discharged | emitted regularly, and is piled up outdoors.

The dust collection water overflowed from the second conditioner tank 34 raises the pH of the dust collection water, and also changes the iron ions in the dust collection water into hydroxides so as to precipitate the caustic soda (hydroxide). Sodium) is added.
When caustic soda is added, iron ions in the dust collection water undergo the reactions shown in the following formulas (1) and (2), change into insoluble iron hydroxide and precipitate in the dust collection water.

Fe ²⁺ + 2OH ⁻ → Fe (OH) ₂ (1)

Fe ³⁺ + 3OH ⁻ → Fe (OH) ₃ (2)

Thereafter, the dust-collected water flows into the thickener 35 after further adding a cationic polymer flocculant.
The iron hydroxide precipitated in the dust collection water in the thickener 35 forms a floc together with other dusts by the action of the polymer flocculant, and settles as sludge on the bottom of the thickener 35.

The sludge settled on the bottom of the thickener 35 is discharged by the sludge pump 36, dehydrated by the dehydrator 37, and then piled up in the field.
The treated water separated from the sludge by the dehydrator 37 is returned to the first conditioner tank 33 by the pump 38.
The iron hydroxide contained in the piled sludge causes a combustion reaction as shown in the following formulas (3) and (4) due to moisture and oxygen in the atmosphere, and generates intense heat.

Fe (OH) ₂ + H ₂ O + 1 / 2O ₂ → Fe (OH) ₃ (3)
2Fe (OH) ₃ → Fe ₂ O ₃ + 3H ₂ O + heat (4)

  On the other hand, the supernatant treated water overflowed from the thickener 35 is stored in the treated water tank 39 and then supplied again to the secondary dust collector 32 by the pump 40 and reused for collecting dust.

The above is the main outline of the circulating water system in which the aeration treatment according to the first embodiment is performed. In this embodiment, the purpose of performing the aeration treatment on the dust collection water is as follows.
(1) By changing the iron ions into insoluble iron oxide by aeration treatment in the circulating water system and precipitating it in the dust collection water, decolorization of the dust collection water is achieved and the iron hydroxide contained in the piled sludge Reduce the amount and prevent iron hydroxide in the sludge from reacting with moisture and oxygen in the atmosphere and burning violently to generate heat.
(2) The carbon dioxide contained in the dust collection water is expelled into the atmosphere by aeration treatment to increase the pH of the dust collection water, and the amount of caustic soda added for pH adjustment is reduced.

In the present embodiment, when the aeration process is performed on the dust collection water, as shown in FIG. 9, the bubbling device 101 having substantially the same configuration as the bubbling device 1 shown in FIGS. Two units were installed in the tank 33.
The first conditioner tank 33 is a circular water tank having a depth of about 3250 mm and a volume of about 24.7 m ³ , and is provided with an inflow cylinder 33a through which dust collection water flows. On the inner periphery on the upper end side of the first conditioner tank 33, a gutter 33b is formed for receiving the overflowing dust collection water.
In this embodiment, two bubbling devices 101 are installed in the inflow tube 33a so that the depth from the water surface is 1500 mm.

  The bubbling device 101 used in the present embodiment has substantially the same configuration as the bubbling device 1 shown in FIGS. 1 to 5, but the number of first through holes and second through holes is different.

The number of first and second through holes of the bubbling device 101 used in this example was set as follows.
Number of first through holes: n1 = p × q
Number of second through holes: n2 = q
Here, p is the number of concentric circles centered on the center of the top of the dome-shaped container, q is the number of first through holes formed on each concentric circle, and the bubbling device 101 of the present embodiment. Then, p = 3 and q = 6 were set.
That is, a total of 18 first through-holes were formed on each of the three concentric circles, and six second through-holes were formed so as to match the number of first through-holes on each concentric circle.

The height of the dome-shaped container (H1 (see FIG. 1)) is 60 mm, and the diameters of three concentric circles centered on the center of the top of the dome-shaped container (D1, D2, D2 (see FIG. 2)) Were set to 65 mm, 80 mm, and 95 mm, respectively.
The heights of the three concentric circles (H2, H3, H4 (see FIG. 1)) with respect to the flange portion of the dome-shaped container were set to 58 mm, 47 mm, and 27 mm, respectively.

On the other hand, the height (H5 (see FIG. 5)) of the second through-hole with respect to the top of the dome-shaped container was set to 35 mm.
The diameter of the first through hole (D4 (see FIG. 5)) is 1.5 mm, the diameter of the second through hole (D5 (see FIG. 5)) is 2.0 mm, and the second through hole is inclined downward with respect to the horizontal direction. The angle (θ (see FIG. 5)) was set to 40 °.

The aeration treatment was performed by supplying pure oxygen (oxygen concentration: 99.5%) to the two bubbling apparatuses 101 at a flow rate of 60 to 70 Nm ³ / hr and industrial water at a flow rate of 25 to 30 ml / min. .
Pure oxygen is supplied from an oxygen pipe 42 in the factory to a common pipe connected to a receiving port of each bubbling device through a pressure reducing valve 43 and a flow meter 44, and industrial water is supplied from an industrial water tank 45 to a pump 46 and a flow rate. It was supplied to the pipe through a total 47 before the receiving port.
It should be noted that not only pure oxygen but also industrial water is supplied to the bubbling device 101 together with the collection of pure water and pure oxygen by jetting pure oxygen and industrial water from the first and second through holes together. This is because the contact efficiency is improved, and furthermore, the growth of scale around the first and second through holes can be suppressed by the erosion effect caused by the industrial water spouted with pure oxygen.
During the test, the flow rate of the dust collection water was 400 m ³ / hr, and the pH of the dust collection water was adjusted to maintain 9.5 to 10.0. The changes in the water quality of the collected and treated water with and without aeration treatment are as shown in Table 1 below.

  As is clear from Table 1, by performing the aeration treatment with oxygen in the first conditioner tank 33, it is possible to control the target pH similarly to the treatment using only the addition of caustic soda, and the iron in the water (total iron, dissolved Iron), turbidity, and SS were sufficiently removed.

As described above, during the test, the pH control of the dust collection water was appropriately performed, and iron ions in the dust collection water were sufficiently removed. Therefore, the treatment water was not colored before and after the aeration treatment.
It should be noted that the iron ions in the dust collection water were removed by the aeration process because of the oxidation reaction shown in the following equations (5) and (6), which changed to insoluble iron oxide and deposited in the dust collection water. It is thought that it was because.

^{Fe 2+ → Fe 3+ + e -} (5)
4Fe ³⁺ + 3O ₂ → 2Fe ₂ O ₃ (6)

  And since a lot of iron ions could be changed to iron oxide in the dust collection water system, after starting the aeration process, no intense heat generation was observed in the sludge piled up, and the working environment was improved.

  In addition, the amount of caustic soda added before the thickener 35 in order to maintain the pH of the dust collection water at 9.5 to 10.0 was an average of 2199 kg per day when the aeration treatment was not performed. However, during the period in which the aeration treatment was performed, the average amount was 461 kg per day, and the amount of caustic soda used could be reduced by about 80% by the aeration treatment.

  This is because the concentration of dissolved oxygen in the dust collection water increases due to aeration treatment, and saturated carbon dioxide that can no longer be dissolved in the dust collection water is expelled into the atmosphere, and the hydroxylation shows strong basicity in an aqueous solution such as caustic soda. This is probably because the pH of the dust collection water could be raised without depending on things.

  In addition, when aeration processing is performed with a normal bubbling device that does not include the second nozzle member as in the present invention, the injection port is blocked due to scale adhesion or sludge accumulation in about three days, and the aeration processing cannot be performed. However, the bubbling device 101 used in this example could continue to be used without being blocked for 2 months.

In addition, the aeration treatment using pure oxygen increased the dissolved oxygen in the treated water, and when it was reused for dust collection, there was a concern about raising the oxygen concentration in the converter gas to the explosion concentration. The dissolved oxygen concentration of water was also confirmed during the test period.
The results are as shown in Table 2 below, and no significant difference was found in the dissolved oxygen concentration with or without aeration treatment with pure oxygen.

(Example 2)
As Example 2, a bubbling device having substantially the same configuration as the bubbling device shown in FIGS. 1 to 5 was installed in the circulating water system of blast furnace dust collection water, and aeration treatment was performed on the dust collection water.
The purpose of performing the aeration treatment in this embodiment is to reduce the amount of caustic soda added for adjusting the pH of the dust collection water.

Blast furnace dust collection water has a lower content of iron ions that cause coloring than converter dust collection water, and coloring of dust collection water does not matter so much, so iron ions are oxidized as in Example 1 above. It is not the main purpose of this embodiment to let it precipitate in the dust collection water.
In other words, in this embodiment, it is only necessary to drive carbon dioxide out of the dust collection water by the aeration treatment to raise the pH of the dust collection water. Therefore, the aeration treatment was performed with air instead of pure oxygen as in the first embodiment.

  The circulating water system of the blast furnace dust collection water is substantially the same as the circulating water system of the converter dust collection water shown in FIG. 6, but a single conditioner tank is used instead of the two conditioner tanks (first and second conditioner tanks 33 and 34). Different points are used.

  In this example, one bubbling device having substantially the same configuration as the bubbling device 1 shown in FIGS. 1 to 5 was installed in the inflow cylinder of the conditioner tank so that the depth from the water surface was 1000 mm.

  The bubbling device 101 used in the present embodiment has substantially the same configuration as the bubbling device 1 shown in FIGS. 1 to 5, but the number of first through holes and second through holes is different.

The number of first and second through holes of the bubbling device used in this example was set as follows.
Number of first through holes: n1 = p × q
Number of second through holes: n2 = q
Here, p is the number of concentric circles centered on the center of the top of the dome-shaped container, q is the number of first through holes formed on each concentric circle, and in the bubbling device of this embodiment, p = 3 and q = 4 were set.
That is, a total of 12 first through holes were formed on each of three concentric circles, and four second through holes were formed so as to match the number of first through holes on each concentric circle.

The height of the dome-shaped container (H1 (see FIG. 1)) is 60 mm, and the diameters of three concentric circles centered on the center of the top of the dome-shaped container (D1, D2, D3 (see FIG. 2)). Were set to 65 mm, 80 mm, and 95 mm, respectively.
The heights of the three concentric circles (H2, H3, H4 (see FIG. 1)) with respect to the flange portion of the dome-shaped container were set to 58 mm, 47 mm, and 27 mm, respectively.

On the other hand, the height (H5 (see FIG. 5)) of the second through-hole with respect to the top of the dome-shaped container was set to 35 mm.
The diameter of the first through hole (D4 (see FIG. 5)) is 1.5 mm, the diameter of the second through hole (D5 (see FIG. 5)) is 2.0 mm, and the second through hole is inclined downward with respect to the horizontal direction. The angle (θ (see FIG. 5)) was set to 40 °.

The aeration treatment was performed by supplying air to the bubbling device at a flow rate of 20 to 50 Nm ³ / hr and industrial water at a flow rate of 100 ml / min. The method for supplying air and industrial water to the bubbling device is the same as in the first embodiment.
The industrial water is supplied to the bubbling device together with the air in the same manner as in the first embodiment. The air and the industrial water are ejected from the first and second through holes together to contact the dust collection water and the air. This is because the efficiency can be increased, and furthermore, the growth of scale around the first and second through holes can be suppressed by the erosion effect caused by the industrial water ejected together with the air.
During the test, the flow rate of the dust collection water was 550 m ³ / hr, and the pH of the dust collection water was adjusted to maintain 6.6. The changes in the water quality of the collected and treated water with and without aeration treatment were as shown in Table 3 below.

  As is apparent from Table 3, by performing aeration treatment with air in the conditioner tank, it is possible to control the target pH as in the case of treatment only with addition of caustic soda, and all iron and zinc in water (total zinc, dissolved) Zinc), turbidity and SS were sufficiently removed.

  As a result, the amount of caustic soda added to maintain the pH of the dust collection water at 6.6 averaged 2500 kg per day during the period when the aeration treatment was not carried out, but the aeration treatment was carried out. During this period, the average amount was 670 kg per day, and the amount of caustic soda used was reduced by about 73% by aeration treatment.

  In addition, when an aeration process is performed with a normal bubbling device that does not include the second nozzle member as in the present invention, the injection port is blocked by scale adhesion or sludge accumulation in about half a month, and the aeration process cannot be performed. However, the bubbling device used in this example could continue to be used without being blocked for 6 months.

  As mentioned above, although the processing method of the blast furnace or converter dust collection water using the bubbling apparatus of this invention was demonstrated, the bubbling apparatus by this invention requires not only the processing of the dust collection water of a blast furnace and a converter but an aeration process. It can utilize suitably for processing of various liquids.

  Further, in Examples 1 and 2 described above, aeration treatment was performed by adding industrial water to oxygen or air, but this was performed by slowly injecting not only gas but also liquid from the injection port, so that the liquid gradually collided. This is because erosion is generated in the vicinity of the injection port, and the effect of mechanically separating scales and deposits that are about to adhere to the injection port is enhanced.

DESCRIPTION OF SYMBOLS 1,101 Bubbling apparatus 2 1st nozzle member 3 1st injection port 4 2nd nozzle member 5 2nd injection port 6 Receiving port 7 Pressure accumulation container 8 Bottom plate member 9 Dome-shaped container 9a Top part 9b Top opening 9c Notch 9d, 12a , 13a, 15a Flange 10 First through-holes 11a, 11b, 11c Concentric circle 12 Tubular body 13 Lid 14 Second through-hole 15 Joint 15b Protrusion 16 First packing ring 17 Second packing ring 18 Flange nut 19 Locking nut 20 Packing 20a Through-hole 21 Bolt 22 Nut 23 Presser ring 30 Converter 31 Primary dust collector 32 Secondary dust collector 33 First conditioner tank 34 Second conditioner tank 35 Thickener 36 Waste mud pump 37 Dehydrators 38, 40, 41, 46 Pump 39 Treated water tank 42 Oxygen piping 43 Pressure reducing valve 44, 47 Flow meter 45 water tank

Claims (11)

  A first nozzle member that receives the compressed gas and injects the compressed gas from the first injection port; and a second nozzle member that receives the compressed gas and injects the compressed gas from the second injection port. A bubbling device arranged to be injected from the second injection port to the periphery of the first injection port.   The bubbling device according to claim 1, wherein the first nozzle member includes a pressure accumulating container having a receiving port for receiving compressed gas and the first injection port.   The pressure accumulating container is composed of a bottom plate member having the receiving port in the center, and a dome-shaped container that is hermetically installed on the bottom plate member, and a second nozzle member is provided to protrude from the top of the dome-shaped container. The bubbling device according to claim 2.   The first injection port is composed of a plurality of first through holes formed on a concentric circle centered on the top of the dome-shaped container, and the second nozzle member is a cylindrical body provided in communication with the dome-shaped container. And a lid fitted into the upper end of the cylindrical body, and the second injection port comprises a plurality of second through holes formed radially around the lid corresponding to the first through holes. Bubbling device.   The bubbling device according to claim 4, wherein the receiving port and the cylindrical body are coaxial with a central axis of the dome-shaped container.   The bubbling device according to any one of claims 3 to 5, wherein the surface of the dome-shaped container is mirror-finished.   Using the bubbling device according to any one of claims 1 to 6, the dust collection water contains oxygen in a circulating water system of dust collection water that collects dust contained in gas discharged from a blast furnace or a converter. A method for treating blast furnace or converter dust collection water, wherein aeration treatment is performed with gas.   The method for treating blast furnace or converter dust collection water according to claim 7, wherein the gas containing oxygen is air.   The method for treating blast furnace or converter dust collection water according to claim 7, wherein the gas containing oxygen is pure oxygen.   The circulating water system includes a thickener for precipitating dust contained in the dust collection water, and the aeration treatment is performed before the dust collection water flows into the thickener or the blast furnace according to any one of claims 7-9. Treatment method of converter dust collection water.   The circulating water system is provided with a conditioner tank on the upstream side of the thickener in advance for removing heavy debris having a large particle size before the collected water flows into the thickener, and the aeration process is performed in the conditioner tank. The blast furnace or converter dust collection water treatment method as described in 1.

Images