WO2019230276A1 - Method for treating treatment liquid and method for treating exhaust gas - Google Patents

Abstract

This method for treating a treatment liquid comprises a removal step for removing impurities from a filtrate h to obtain a boron solution k, by circulating, through an anion exchange resin 11, the filtrate h as a treatment liquid containing boron, calcium, and a nitrous acid. Furthermore, this method for treating a treatment liquid comprises, prior to the removal step, a reduction step in which a reducing agent m containing a sulfamic acid is added to the filtrate h.

Description

Treatment liquid treatment method and exhaust gas treatment method

The present invention relates to a treatment liquid treatment method and an exhaust gas treatment method.

In a glass melting furnace, molten glass is produced by heating powdery or granular glass raw materials with a burner that burns gas fuel. The molten glass becomes various glass articles such as a glass plate and a glass tube through a predetermined forming step.

At this time, in the exhaust gas generated from the glass melting furnace, a part of the components contained in the glass raw material is contained in a gas or fine solid state. For this reason, many components that can be recycled as a glass raw material are contained in the exhaust gas. Therefore, if the recycled material can be recovered from the exhaust gas, it can contribute to saving of the glass material. At the same time, the environment can be considered.

As one of such methods, for example, Patent Document 1 discloses that a recycled raw material containing boron is recovered from an exhaust gas of a glass melting furnace that melts a glass raw material containing boron. Specifically, wet collection, neutralization, solid-liquid separation, etc. are performed on the exhaust gas to obtain a treatment liquid (extraction liquid) containing boron, calcium and other impurities, and then the treatment liquid is distributed to the anion exchange resin. It is disclosed that impurities are removed from the treatment liquid by obtaining the boron solution containing the recycle raw material.

JP 2013-180284 A

The above treatment liquid contains, for example, boron derived from a glass raw material, and calcium is added to neutralize the treatment liquid.

In addition, the treatment liquid contains, for example, a halide such as chlorine (including halide ions and halide salts) as impurities. Halides are derived from fining agents and the like. Impurities are removed by passing the treatment liquid through the anion exchange resin.

The treatment liquid further contains nitrous acid. Nitrous acid is derived from the nitrogen component of the glass raw material and / or gas fuel. When nitrous acid is contained in the treatment liquid, the anion exchange resin is likely to be deteriorated, and the resin life may be remarkably reduced. This is considered to be due to the oxidizing action of nitrous acid.

An object of the present invention is to extend the life of an anion exchange resin for removing impurities from a treatment liquid.

The present invention, which was created to solve the above problems, is a removal step of removing impurities from a treatment liquid to obtain a boron solution by circulating the treatment liquid containing boron, calcium and nitrous acid through an anion exchange resin. The method further comprises a reduction step of adding a reducing agent containing sulfurous acid to the treatment liquid before circulating the treatment liquid through the anion exchange resin. According to such a configuration, nitrous acid contained in the treatment liquid is reduced by the reducing agent. As a result, nitrous acid can be reduced from the treatment liquid before the treatment liquid is passed through the anion exchange resin. Therefore, the life of the anion exchange resin can be extended. Here, the term “boron” includes boron compounds such as boron oxide and boric acid and ions thereof. Further, the term “calcium” includes calcium compounds such as slaked lime and ions thereof. The term “nitrite” includes nitrite compounds such as nitrite ions and nitrites. The terms “impurities” and “sulfurous acid” also include ions of each term. The term “removing impurities from the processing solution” includes not only removing impurities completely but also reducing the amount thereof. The term “boron solution” means a solution containing boron as a main component.

In the above configuration, the sulfurous acid is preferably sulfamic acid. The sulfurous acid may be sodium sulfite, sodium thiosulfate, or the like, but may react with calcium dissolved in the treatment liquid to precipitate calcium. On the other hand, sulfamic acid hardly reacts with calcium dissolved in the treatment liquid, and can prevent precipitation of calcium. Therefore, when sulfamic acid is used, a removal facility such as a filter for removing precipitated calcium is not necessary, so that the facility cost can be reduced.

In the above configuration, the reducing agent is preferably added in a pipe through which the treatment liquid flows. If it does in this way, a reducing agent will be automatically stirred by the flow of the process liquid which distribute | circulates the inside of piping. Therefore, since the agitation equipment such as the agitation blade is not necessary, the equipment cost can be reduced.

In the above configuration, the anion exchange resin is preferably a weakly basic anion exchange resin. By doing so, it is possible to prevent boron from adsorbing to the anion exchange resin, so that the boron recovery efficiency can be increased.

In the above configuration, in the removing step, it is preferable to distribute the treatment liquid to the cation exchange resin before the anion exchange resin. When there is too much calcium contained in the treatment liquid, the ion exchange performance of the anion exchange resin may deteriorate. Therefore, by passing the treatment liquid through the cation exchange resin before the anion exchange resin, the calcium in the treatment liquid is adsorbed on the cation exchange resin, and the calcium in the treatment liquid is removed (including reduction). It is preferable.

The present invention devised to solve the above problems is a method for treating exhaust gas in a glass melting furnace that melts a glass raw material containing boron, and the exhaust gas is treated by wet collection or dry collection. By collecting the collected material containing boron and nitrous acid from the solid, separating the collected material after the neutralizing step by solid-liquid separation, adding the neutralizing agent containing calcium to the collected material And a solid-liquid separation step for obtaining a treatment liquid, and a treatment step for treating the treatment liquid to obtain a boron solution by a method having the above-described configuration as appropriate. According to such a configuration, it is possible to efficiently obtain a boron solution capable of recovering a high concentration of boron from exhaust gas, and to extend the life of the anion exchange resin for the reasons already described.

According to the present invention, it is possible to extend the life of the anion exchange resin that removes impurities from the treatment liquid.

It is a flowchart of the processing method of the waste gas concerning an embodiment.

Hereinafter, an embodiment of an exhaust gas treatment method will be described with reference to the accompanying drawings. In the following embodiments of the exhaust gas treatment method, embodiments of the treatment liquid treatment method will also be described. Of course, the treatment method of the treatment liquid is not limited to the case of being incorporated in the treatment method of the exhaust gas, and can be carried out alone as a method of treating the treatment liquid.

As shown in FIG. 1, the exhaust gas treatment method according to this embodiment includes a melting step, a collection step, a neutralization step, a solid-liquid separation step (extraction step), a recovery step, a removal step, and a reduction step. Among these, the processing liquid processing method according to the present embodiment corresponds to the removal step and the reduction step.

(Melting process)
In the melting step, the glass raw material a containing boron prepared so as to have a target glass composition is heated with a burner in the glass melting furnace 1 to produce a molten glass to be borosilicate glass. From the molten glass, glass articles such as a glass plate, a glass roll obtained by winding a glass ribbon into a roll, and a glass tube are produced.

As the gas fuel for the burner, it is preferable to use, for example, LPG or LNG with a low sulfur content. Moreover, it is preferable to use a glass raw material a having a low sulfur content. Furthermore, it is preferable to use oxygen combustion from the viewpoint of reducing nitrous acid in the treatment liquid described later. Alternatively, instead of or in combination with the burner, the glass raw material a may be heated with an electrode immersed in the molten glass.

The exhaust gas b generated from the glass melting furnace 1 contains fine solids and vaporized substances derived from the glass raw material a and the gas fuel of the burner. For this reason, the exhaust gas b contains impurities such as nitrous acid and halide derived from the glass raw material a and / or glass fuel, in addition to boron (including a boron compound) which is a recycled raw material.

(Collection process)
In the collection step, the exhaust gas b generated from the glass melting furnace 1 is introduced into the collection device 2 to obtain a collection liquid c containing boron, nitrous acid and impurities from the exhaust gas b.

In the collection device 2, the exhaust gas b is cooled to, for example, 60 to 70 ° C., and boron contained in the vaporized state is precipitated.

In the present embodiment, the collection device 2 is a wet collection device including a spray tower 3 and a wet electrostatic precipitator 4. In addition, since the wet electrostatic precipitator 4 plays an auxiliary role of the spray tower 3, it may be omitted. The type of the collector 2 is not particularly limited as long as it can wet-collect boron from the exhaust gas b.

Boron (micro solids or vaporized substances) contained in the exhaust gas b is cooled and deposited by contacting with the washing water sprayed in the spray tower 3 and collected as a collection liquid c. Boron remaining in the exhaust gas d that has passed through the spray tower 3 is also collected as the collected liquid c by contacting with the washing water of the wet electrostatic precipitator 4. These collected liquids c become collected matter. As boron is collected by the collection device 2, nitrous acid and impurities contained in the exhaust gas b are also collected as the collection liquid c. Here, since the washing water containing boron is used as the washing water for the spray tower 3 and the wet electrostatic precipitator 4, the boron concentration of the collection liquid c is saturated or close to that. For this reason, a part of boron contained in the collection liquid c becomes undissolved.

The exhaust gas e purified by passing through the wet electrostatic precipitator 4 is discharged from the chimney 5 to the atmosphere (outside the system).

(Neutralization process)
In the neutralization step, the collection liquid c collected by the spray tower 3 and the wet electric dust collector 4 is introduced into the neutralization tank 6.

In the neutralization tank 6, an alkaline neutralizing agent f containing calcium such as slaked lime is added to the collected liquid c to neutralize the acidic collected liquid c. Specifically, neutralization is performed so that the hydrogen ion concentration (pH) of the collection liquid c is weakly alkaline, preferably 7.5 to 12.0, more preferably 8.0 to 10.0. Thereby, while preventing the corrosion by piping etc. in a post process, the solubility of the boron in the collection liquid c can be lowered | hung and the collection | recovery efficiency can be raised.

(Solid-liquid separation process)
In the solid-liquid separation step, the collected liquid g neutralized in the neutralization tank 6 is introduced into the solid-liquid separation device 7.

In the solid-liquid separation device 7, the collected liquid g is solid-liquid separated and separated into a filtrate h and a cake i. Therefore, the filtrate h is a processing liquid in the processing liquid processing method according to the present embodiment.

The calcium, nitrous acid, and impurities contained in the collected liquid g are often dissolved in the collected liquid g, and most of them are recovered as the filtrate h. On the other hand, as described above, a part of the boron in the collection liquid g is contained undissolved. Further, a part of calcium in the collection liquid g is also included in an undissolved state. For this reason, some boron and calcium contained in the collection liquid g are collected as filtrate h, and the rest are collected as cake i. Therefore, the filtrate h contains boron, calcium, nitrous acid, and impurities (halides). In addition, each of these substances may be included in the state of compounds such as ions and salts.

Examples of the solid-liquid separator 7 include a filter press, centrifugal separation, and vacuum filtration, but the type is not particularly limited.

(Recovery process)
In the recovery process, the cake i is introduced into the dryer 8 as a recovery means, and the recycled material j is recovered from the cake i.

In the dryer 8, moisture contained in the cake i is removed by drying, and a dried powdery recycled material j is obtained. The obtained recycled raw material j is supplied to the glass melting furnace 1 together with the glass raw material a.

Here, since the cake i to be dried contains boron, boron with less impurities can be recovered by removing moisture by drying. Moreover, since calcium can be used for a glass raw material, for example as calcium oxide, there is no problem even if it is recovered together with boron. Of course, you may perform the removal process of calcium with respect to the cake i (or recycling raw material j) so that calcium may not be collect | recovered.

Examples of the dryer 8 include a vacuum dryer, a rotary dryer, a band dryer, and a spray dryer, but the type is not particularly limited.

(Removal process)
In the removal step, the filtrate h, which is a treatment liquid, is introduced into the ion exchange resin tower 9, and impurities are removed from the filtrate h to obtain a boron solution k.

The ion exchange resin tower 9 includes a cation exchange resin 10 disposed on the upstream side (solid-liquid separator 7 side) and an anion exchange resin 11 disposed on the downstream side. For example, the cation exchange resin 10 is a strongly acidic cation exchange resin, and the anion exchange resin 11 is a weakly basic anion exchange resin. When a weakly basic anion exchange resin is used, adsorption of boron in the filtrate h can be suppressed.

In the cation exchange resin 10, calcium contained in the filtrate h is removed (including reduction), and in the anion exchange resin 11, impurities (eg, halides) contained in the filtrate h are removed (including reduction). Is done. Thereby, calcium and impurities can be removed from the filtrate h to obtain a boron solution k. The obtained boron solution k is supplied as washing water to the above-described collection device 2 (spray tower 3 and / or wet electrostatic precipitator 4). In this way, since the boron concentration of the washing water is saturated or close to that state, it becomes difficult for boron to be dissolved in the collection liquid c. As a result, boron tends to remain as an undissolved substance and is easily recovered as cake i by solid-liquid separation.

The solid-liquid separator 7 and the cation exchange resin 10 and the cation exchange resin 10 and the anion exchange resin 11 are connected by pipes, respectively.

Note that the boron solution k may contain calcium. Further, the cation exchange resin 10 may be omitted. However, if there is too much calcium, the ion exchange performance of the anion exchange resin 11 may deteriorate, so it is preferable to place the cation exchange resin 10 upstream of the anion exchange resin 11.

(Reduction process)
Here, the filtrate h contains nitrous acid. Nitrous acid degrades the anion exchange resin 11 and causes a reduction in the resin life. Therefore, the exhaust gas treatment method according to the present embodiment includes a reduction step of adding a reducing agent m containing sulfurous acid to the filtrate h before the removal step. Sulfurous acid may be contained in an ionic state.

Reducing agent m reduces nitrous acid contained in filtrate h. As a result, nitrous acid can be removed (including reduction) from the filtrate h before flowing the filtrate h through the anion exchange resin 11. Therefore, the life of the anion exchange resin 11 can be extended. Specifically, for example, the lifetime of the anion exchange resin 11 extends from 1 year to 3 years.

Examples of sulfurous acid contained in the reducing agent m include sodium sulfite, sodium thiosulfate, and sulfamic acid (also referred to as amidosulfuric acid). In this embodiment, sulfamic acid is used. Sulfamic acid does not easily react with calcium dissolved in the filtrate h, and can prevent precipitation of calcium. Therefore, when sulfamic acid is used, removal equipment such as a filter for removing precipitated calcium is not necessary, and equipment costs can be reduced.

The reaction of nitrite (MNO ₂ ) and sulfamic acid (H ₃ NSO ₃ ) is represented by the following reaction formula. Nitrogen gas generated by the reaction is released from the ion exchange resin tower 9 into the atmosphere (outside the system). Further, hydrogen sulfate ions (MHSO ₄ ) are removed (including reduction) by the anion exchange resin 11.
MNO ₂ + H ₃ NSO ₃ → MHSO ₄ + N ₂ + H ₂ O
Where M is a monovalent cation

The amount of sulfamic acid added is appropriately adjusted according to the concentration of nitrite. If the concentration of nitrite is about 1000 ppm, the amount of sulfamic acid added can be 100 ppm to 1000 ppm. In order to increase the reaction rate by adding sulfamic acid in excess, the amount of sulfamic acid added may be over 1000 ppm, and is preferably 5000 ppm or more. Since the improvement in the reaction rate due to excessive addition is saturated, the amount of sulfamic acid added is preferably 15000 ppm or less.

In this embodiment, the reducing agent m is added in the pipe from the solid-liquid separator 7 to the cation exchange resin 10. Thereby, the reducing agent m is automatically stirred by the flow of the filtrate h that circulates in the pipe. As a result, since it is not necessary to provide a separate stirring facility, the facility cost can be reduced.

Here, the reaction between nitrite and sulfamic acid tends to occur in an acidic environment. After removing calcium with the cation exchange resin 10, since a halide (for example, chlorine) remains, the pH of the filtrate h decreases and becomes acidic. Therefore, it is considered that the reaction between nitrite and sulfamic acid mainly occurs on the downstream side of the cation exchange resin 10, that is, between the cation exchange resin 10 and the anion exchange resin 11. However, it is considered that the reaction between nitrite and sulfamic acid proceeds slowly even upstream of the cation exchange resin 10.

Note that the addition position and addition method of the reducing agent m are not particularly limited as long as they are upstream of the anion exchange resin 11. For example, the reducing agent m may be added in a pipe from the cation exchange resin 10 to the anion exchange resin 11. Further, a tank for temporarily storing the filtrate h and the reducing agent m may be provided on the upstream side of the anion exchange resin 11, and stirring equipment such as stirring blades may be provided in the tank.

The present invention is not limited to the above embodiment, and is not limited to the above-described effects. The present invention can be variously modified without departing from the gist of the present invention.

In the above embodiment, the case where the boron solution obtained in the removing step is supplied to the collecting means has been described. However, the boron solution may be mixed with the cake obtained by solid-liquid separation (for example, Patent Documents). 1 and FIG. 2). In this case, in order to obtain a recycled raw material, the moisture in the mixture of the boron solution and the cake may be directly removed by drying with a spray dryer or the like, or the moisture in the cake obtained by solid-liquid separation of the mixture again is dried under reduced pressure. It may be removed by drying with a machine.

In the above embodiment, the case where the collected liquid is solid-liquid separated only once by the solid-liquid separation apparatus has been described, but the solid-liquid separation may be performed a plurality of times. In this case, for example, the filtrate obtained in each solid-liquid separation is supplied to the ion exchange resin tower, and the boron solution obtained in each ion-exchange resin tower is mixed with the cake obtained in each solid-liquid separation. You may make it (for example, the structure of FIG. 2 of patent document 1).

In the above embodiment, the case where boron is wet-collected from exhaust gas as the collecting means has been described, but boron may be dry-collected from exhaust gas. Examples of the dry collection means include those provided with a cooling tower and a bag filter. In the case of dry collection, since the collected matter becomes collected powder, for example, it is preferably mixed with a liquid component (for example, pure water or a boron solution obtained in the removal step) before solid-liquid separation ( For example, the configuration of FIG.

DESCRIPTION OF SYMBOLS 1 Glass melting furnace 2 Collection apparatus 3 Spray tower 4 Wet electrostatic precipitator 5 Chimney 6 Neutralization tank 7 Solid-liquid separator 8 Dryer 9 Ion exchange resin tower 10 Cation exchange resin 11 Anion exchange resin a Glass raw material b Exhaust gas c Collection liquid (collected matter)
e Exhaust gas f Neutralizer g Collected liquid (collected material)
h Filtrate i Cake j Recycled raw material k Boron solution m Reducing agent

Claims (6)

1. A treatment liquid treatment method comprising a removal step of removing impurities from the treatment liquid to obtain a boron solution by circulating a treatment liquid containing boron, calcium and nitrous acid through an anion exchange resin,
   A treatment method for a treatment liquid, further comprising a reduction step of adding a reducing agent containing sulfurous acid to the treatment liquid before flowing the treatment liquid through the anion exchange resin.
2. The method for treating a treatment liquid according to claim 1, wherein the sulfurous acid is sulfamic acid.
3. 3. The processing liquid treatment method according to claim 1, wherein the reducing agent is added in a pipe through which the processing liquid flows.
4. The treatment liquid treatment method according to any one of claims 1 to 3, wherein the anion exchange resin is a weakly basic anion exchange resin.
5. The treatment liquid treatment method according to any one of claims 1 to 4, wherein, in the removing step, the treatment liquid is circulated through the cation exchange resin before the anion exchange resin.
6. A method for treating exhaust gas from a glass melting furnace for melting glass material containing boron,
   A collection step of obtaining a collected product containing boron and nitrous acid from the exhaust gas by performing wet collection or dry collection on the exhaust gas;
   A neutralization step of adding a neutralizing agent containing calcium to the collected matter;
   A solid-liquid separation step for obtaining a treatment liquid by solid-liquid separation of the collected matter that has undergone the neutralization step; and
   A method for treating exhaust gas, comprising a treatment step of treating the treatment liquid to obtain a boron solution by the method according to any one of claims 1 to 5.

Images