KR20220038903A - Method for producing CaF₂from waste water including HF - Google Patents

Abstract

The present invention relates to a method of recycling process wastewater. More particularly, the present invention relates to a method of recycling process wastewater which forms and extracts calcium fluoride (CaF_2) from process wastewater including hydrogen fluoride (HF) created during a process of manufacturing nitrogen trifluoride gas, and to a method of forming a calcium fluoride block including the same. The method of recycling process wastewater which forms and extracts calcium fluoride (CaF_2) from process wastewater including hydrogen fluoride (HF) comprises the following: a metal removing step of extracting and removing at least one metal included in the process wastewater by mixing the process wastewater with a preset organic solvent; a calcium fluoride-containing sludge forming step of forming calcium fluoride-containing sludge by adding calcium hydroxide to the process wastewater from which the metal is removed by the metal removing step; and a calcium fluoride-containing sludge recovering step of separating and recovering the calcium fluoride-containing sludge formed by the calcium fluoride-containing sludge forming step.

Description

Process wastewater recycling method for forming calcium fluoride from process wastewater containing hydrogen fluoride, and calcium fluoride block molding method including the same {Method for producing CaF₂from waste water including HF}

The present invention relates to a process wastewater recycling method, and more particularly, a process wastewater recycling method for forming/extracting calcium fluoride from process wastewater containing hydrogen fluoride generated in a nitrogen trifluoride gas production process, etc., and a calcium fluoride block containing the same It relates to the molding method.

Nitrogen trifluoride (NF ₃ ) gas is used in various processes such as cleaning processes and substrate etching processes by using strong reactivity in manufacturing equipment for manufacturing semiconductors, LCDs, solar cells, and the like.

In particular, as the demand for semiconductors and displays increases rapidly due to the 4th industrial revolution, and the demand for solar cells due to the increase in demand for alternative energy, the amount of nitrogen trifluoride (NF ₃ ) gas is also increasing rapidly.

Meanwhile, the currently known method for producing nitrogen trifluoride (NF ₃ ) is to electrolyze anhydrous hydrofluoric acid (HF) to produce fluorine (F ₂ ) by adding ammonia (NH ₃ ) gas to a fluorine electrolysis tank to produce fluorine gas and ammonia gas. There is a so-called "electrolysis method" in which NF ₃ is obtained by direct reaction, and a so-called "chemical method" in which fluorine gas and ammonia are wet-reacted in a mixed solution of hydrofluoric acid and ammonia to generate NF ₃ gas, and the NF ₃ is separated and purified. .

The above "chemical method" has a problem in that a large amount of reaction by-products are generated as process wastewater because the yield is not high.

That is, there is a problem in that process wastewater containing harmful metals and unreacted NH ₃ , HF is generated in order to perform the nitrogen trifluoride (NF ₃ ) manufacturing method as described above.

Therefore, harmful metals and unreacted NH ₃ , HF present in the process wastewater are highly toxic and therefore need to be discharged to the outside after purification treatment.

As a method for purifying process wastewater produced by the NF ₃ manufacturing process, the method known so far is neutralization treatment by absorbing process wastewater into slaked lime (Ca(OH) ₂ ) or calcium carbonate (CaCO ₃ ) in order to dispose of pollutants. And fluorite (CaF ₂ ) obtained as a precipitate as a result of the neutralization reaction is landfilled, and the supernatant containing ammonia is disposed of using a general industrial wastewater purification system.

At this time, the fluorspar (CaF ₂ ) obtained as a result of the slaked lime treatment has very low solubility and thus has a low risk of contaminating the soil during landfill treatment, so slaked lime is widely used.

However, the conventional process wastewater purification method as described above has a problem in that even when slaked lime is buried, it is still difficult to dispose of as hazardous substances due to the presence of a trace amount of hydrogen fluoride in the slaked lime.

On the other hand, Patent Document 1, by reacting the metal fluoride salt recovered by the input of calcium hydroxide to the process wastewater with sulfuric acid at a high temperature to obtain hydrogen fluoride, that is, nitrogen trifluoride, that is, NF ₃ It presents a technique for reusing raw materials for production.

However, the technology disclosed in Patent Document 1 has an advantage in reusing raw materials for production of nitrogen trifluoride, that is, NF ₃ , but as a result of the additional use of sulfuric acid, a hazardous material, the problem of reprocessing the wastewater and materials remaining after hydrogen fluoride extraction is still remains

On the other hand, gas containing hydrogen fluoride is used in semiconductor processes in addition to the nitrogen trifluoride manufacturing process, and process wastewater containing hydrogen fluoride is generated even in the semiconductor process, so efficient treatment is required.

(Patent Document 1) KR10-2018-0064753 A

An object of the present invention is to minimize harmful substances generated in the gas production process using hydrogen fluoride by reprocessing it so that it can be recycled for industrial purposes in reproducing it into calcium fluoride from process wastewater containing hydrogen fluoride (HF). An object of the present invention is to provide a process wastewater recycling method capable of greatly improving productivity by recycling by-products for industrial use, and a calcium fluoride block molding method including the same.

The present invention was created to achieve the object of the present invention as described above, and the present invention is a process wastewater recycling method for forming calcium fluoride from process wastewater containing hydrogen fluoride, the process wastewater and a preset organic solvent a metal removal step of extracting and removing one or more metals contained in the process wastewater by mixing; a calcium fluoride sludge forming step of forming calcium fluoride-containing sludge by adding calcium hydroxide to the process wastewater from which the metal has been removed by the metal removal step; Disclosed is a process wastewater recycling method comprising a calcium fluoride sludge recovery step of separating and recovering the calcium fluoride-containing sludge formed by the calcium fluoride sludge forming step.

The process wastewater recycling method according to the present invention comprises: a calcium fluoride stirring step of adding the calcium fluoride sludge recovered by the calcium fluoride sludge recovery step to a preset amount of water and stirring and mixing; a residual metal removal step of extracting and removing one or more metals by mixing a predetermined organic solvent with the water in which the calcium fluoride-containing sludge is added; The method may further include a sludge collection step of extracting calcium fluoride-containing sludge by solid-liquid separation after performing the residual metal removal step and collecting it in a preset collection container 10 .

In addition, the process wastewater recycling method according to the present invention is a calcium fluoride block forming method according to the present invention, wherein the metal removal step to the calcium fluoride sludge collection step are performed in a calcium fluoride-containing sludge extraction line, and the collection container (10) ) by heating the calcium fluoride-containing sludge supplied from the heating chamber 100 to remove HF and NH ₃ and moisture to form calcium fluoride powder, and the calcium fluoride powder supplied from the heating chamber 100 and a binder for solidification A binder mixing unit 200 to form a differentiated calcium molding by mixing with, and a block molding unit 300 to form a plurality of calcium fluoride blocks by heating and pressurizing the differentiated calcium molding formed by the binder mixing unit 200 is performed by a calcium fluoride block forming line including ) from the calcium fluoride-containing sludge extraction line to the calcium fluoride block forming line (S310); a sludge supply step (S320) of supplying calcium fluoride-containing sludge from the collection container 10 transferred to the calcium fluoride block forming line into the heating chamber 100; A heating step of heating the calcium fluoride-containing sludge supplied from the collection container 10 in a state in which the heating chamber 100 is isolated from the outside to remove HF and NH ₃ and moisture to form a calcium fluoride powder (S330); a binder mixing step (S340) of receiving calcium fluoride powder from the heating chamber 100 and mixing it with a binder for solidification to form a differentiated calcium molding; It may include a block molding step (S350) of forming a plurality of calcium fluoride blocks by heating and pressurizing the differentiated calcium molding formed by the binder mixing unit 200 .

The process wastewater recycling method and the calcium fluoride block molding method comprising the same according to the present invention are regenerated into calcium fluoride from the process wastewater generated during the production of a gas containing fluorine, for example, nitrogen trifluoride (NF ₃ ) gas. In this way, it is reprocessed so that it can be recycled for industrial use, especially for other industrial uses, thereby minimizing harmful substances generated in the manufacturing process of nitrogen trifluoride (NF ₃ ) gas, and recycling by-products for industrial use, thereby greatly improving productivity. there is.

Furthermore, the process wastewater recycling method and the calcium fluoride block molding method comprising the same according to the present invention perform a process using a gas containing fluorine, for example, in reproducing it into calcium fluoride from process wastewater generated in a semiconductor process. , it has the advantage of greatly improving productivity by reprocessing it so that it can be recycled for industrial purposes, especially other industrial uses, while minimizing harmful substances generated in the process of manufacturing fluorine-containing gas and recycling by-products for industrial use.

1 is a flowchart showing a process wastewater recycling method and a calcium fluoride block molding method including the same according to the present invention.
FIG. 2 is a conceptual diagram showing an example of a calcium fluoride block forming line for performing the calcium fluoride block forming method among the process wastewater recycling method of FIG. 1 .
3 is a conceptual diagram showing an example of a block forming part of the calcium fluoride block forming line of FIG. 2 .
FIG. 4 is a conceptual diagram showing an example of a heating chamber in the forming line of the calcium fluoride block of FIG. 2 .

Hereinafter, a process wastewater recycling method for forming calcium fluoride from process wastewater containing hydrogen fluoride according to the present invention and a calcium fluoride block molding method including the same will be described with reference to the accompanying drawings.

The present invention provides a process wastewater recycling method, a process wastewater recycling method for forming calcium fluoride from process wastewater containing hydrogen fluoride, and a calcium fluoride block molding method including the same, wherein the process wastewater containing hydrogen fluoride is described below. Nitrogen trifluoride (NF ₃ ) gas manufacturing process, of course, a manufacturing process containing fluorine, for example, a process wastewater generated according to the semiconductor process, all process wastewater containing hydrogen fluoride can be applied.

That is, as an embodiment of the present invention, the present invention provides a gas containing fluorine, for example, nitrogen trifluoride (NF ₃ ) gas manufacturing process as well as a manufacturing process containing fluorine, for example, according to the semiconductor process. Calcium fluoride (CaF ₂ ) is formed from the generated process wastewater so that it can be recycled in the industrial field.

In particular, the calcium fluoride (CaF ₂ ) is used to remove impurities contained in steel in iron making and steel making processes, and nitrogen trifluoride (NF ₃ ) processes containing hydrogen fluoride, such as process wastewater generated in the gas manufacturing process, etc. When calcium fluoride (CaF ₂ ) is formed from wastewater and used in iron and steel manufacturing processes, hazardous substances generated in manufacturing processes that generate process wastewater containing hydrogen fluoride, such as nitrogen trifluoride (NF ₃ ) gas manufacturing process, semiconductor process, etc. It is possible to greatly improve productivity by minimizing waste and recycling by-products for industrial use.

However, the process wastewater generated in the nitrogen trifluoride (NF ₃ ) gas manufacturing process contains not only highly toxic hydrogen fluoride (HF) but also metal materials such as Cu, Fe, Ni, Zn, and calcium fluoride (CaF) from the process wastewater. ₂ ), there is a problem in that it cannot be used in iron and steel manufacturing processes because it contains highly toxic hydrogen fluoride (HF) as well as metal materials such as Cu, Fe, Ni, and Zn.

Accordingly, the present invention is to provide a process wastewater recycling method for forming calcium fluoride that can be used for other industrial purposes, in particular, for iron making and steel making, and a method for forming a calcium fluoride block comprising the same.

For this purpose, the process wastewater recycling method for forming calcium fluoride from process wastewater containing hydrogen fluoride according to the present invention mixes process wastewater and a preset organic solvent to extract and remove one or more metals contained in process wastewater a metal removal step (S10) and; A calcium fluoride sludge forming step (S20) of forming calcium fluoride-containing sludge by adding calcium hydroxide (Ca(OH) ₂ ) to the process wastewater from which the metal has been removed by the metal removal step (S10); It is characterized in that it comprises a calcium fluoride sludge recovery step (S30) of separating and recovering the calcium fluoride-containing sludge formed by the calcium fluoride sludge formation step (S20).

The metal removal step (S10) is a step of extracting one or more metals contained in the process wastewater by mixing the process wastewater and a preset organic solvent, that is, removing the metal material from the process wastewater by a known organic solvent method. method can be carried out.

Here, since the process wastewater contains metal materials such as Cu, Fe, Ni, Zn, an organic solvent suitable for the type of metal material to be removed may be selected and used.

In addition, the metal removal step (S10) may be performed through a plurality of steps according to the number of metal materials to be removed by using an organic solvent corresponding to the type of metal material to be removed since the types of metal materials to be removed are various. there is.

Meanwhile, in the metal removal step (S10), when the final calcium fluoride is used for iron making or steel making, the removal of iron (Fe) is unnecessary, so the removing step of iron (Fe) may be omitted.

Meanwhile, in the metal removal step (S10), the metal material is removed through separation of the organic solvent and aqueous solution containing the metal material according to the principle of the organic solvent method.

The calcium fluoride sludge formation step (S20) is a step of forming calcium fluoride-containing sludge by adding calcium hydroxide (Ca(OH) ₂ ) to the process wastewater from which the metal has been removed by the metal removal step (S10). can be performed by

In particular, in the calcium fluoride sludge formation step (S20), when calcium hydroxide (Ca(OH) ₂ ) is added to the process wastewater from which the metal has been removed by the metal removal step (S10), calcium fluoride (CaF ₂ ) is produced by a chemical reaction. will form

Specifically, the process wastewater from which the metal is removed by the metal removal step (S10) is changed to an aqueous solution in which hydrogen fluoride and ammonia are dissolved as the metal material is removed.

Accordingly, in the calcium fluoride sludge formation step (S20), calcium hydroxide (Ca(OH) ₂ ) is added to the process wastewater from which the metal has been removed by the metal removal step (S10), and calcium fluoride (CaF ₂ ) is produced by a chemical reaction. to form

Here, the input amount of calcium hydroxide (Ca(OH) ₂ ) may be determined by the amount of hydrogen fluoride contained in the process wastewater through an experiment or the like.

And by stirring after the addition of the calcium hydroxide (Ca(OH) ₂ ), it is possible to promote a chemical reaction for the formation of calcium fluoride (CaF ₂ ).

The calcium fluoride sludge recovery step (S30) is a step of separating and recovering the calcium fluoride-containing sludge formed by the calcium fluoride sludge formation step (S20), and can be recovered by various methods.

For example, in the calcium fluoride sludge recovery step (S30), the formed calcium fluoride (CaF ₂ ) can be performed using a property insoluble in water, and as a physical separation method, it is separated using a filter member, or by precipitation, etc. can be separated

On the other hand, the calcium fluoride sludge recovered by performing the primary treatment step (S100) including the metal removal step (S10) to the calcium fluoride sludge recovery step (S30) is used for steelmaking and steelmaking by treating a large amount of process wastewater. There is a problem in that the purity of hydrogen fluoride is not suitable to the extent used in the present invention.

Furthermore, calcium fluoride sludge recovered by performing the first treatment step (S100) is not sufficiently removed of the corresponding metal material by the metal removal step (S10). There is a problem that may cause defects in the steelmaking and steelmaking processes.

Furthermore, the calcium fluoride sludge collected by performing the primary treatment step (S100) including the metal removal step (S10) to the calcium fluoride sludge recovery step (S30) still contains highly toxic hydrogen fluoride and harmful metal substances. There is a problem that industrial recycling is impossible because recycling or reprocessing of the waste is impossible due to the existence of the waste.

Accordingly, in the recycling method according to the present invention, the calcium fluoride sludge recovered by the primary treatment step (S100), that is, the calcium fluoride sludge recovery step (S30) is added to a preset amount of water, stirred and mixed. (S210) and; a residual metal removal step (S220) of extracting and removing one or more metals by mixing a preset organic solvent with the water in which the calcium fluoride-containing sludge is added; After performing the residual metal removal step (S230), a secondary treatment step (S200) including a sludge collecting step (S230) of extracting calcium fluoride-containing sludge by solid-liquid separation and collecting it in a preset collection container 10 is additionally performed may include

The calcium fluoride stirring step (S210) is a step of mixing the calcium fluoride sludge recovered by the calcium fluoride sludge recovery step (S30) into a preset amount of water and stirring to mix, and a residual metal removal step (S220) to be described later. It is a step for the implementation of

Here, the amount of water added is an amount capable of performing the residual metal removal step (S220), which will be described later, in a state in which hydrogen fluoride is dissolved by stirring.

The residual metal removal step (S220) is a step of extracting and removing one or more metals by mixing a preset organic solvent with water in which calcium fluoride-containing sludge is added, and may be performed by various methods.

Here, the residual metal removal step (S220) is similar to the metal removal step (S10) described above, and a detailed description thereof will be omitted.

However, the residual metal removal step ( S220 ) may be performed using a small amount of an organic solvent as compared to the metal removal step ( S10 ) described above since the residual metal material is in a trace amount.

On the other hand, the residual metal removal step (S220), through experiments, removes the residual metal material below the allowable metal content to be used for iron making and steel making.

The sludge collection step (S230) is a step of extracting calcium fluoride-containing sludge by solid-liquid separation after performing the residual metal removal step (S230) and collecting it in a preset collection container 10, which can be performed by various methods. there is.

Here, the collection container 10 is a container in which calcium fluoride-containing sludge extracted by solid-liquid separation after performing the residual metal removal step (S230) is contained. Considering that it is difficult to completely remove moisture in the container, some moisture It is collected in the state it contains.

Meanwhile, as described above, in the metal removal step (S10) to the calcium fluoride sludge collection step (S230), that is, the first treatment step (S100) and the second treatment step (S200), highly toxic hydrogen fluoride is produced in the process. It needs to be carried out in a limited space, including hazardous processes such as emissions.

To this end, the metal removal step (S10) to the calcium fluoride sludge collection step (S230), that is, the first treatment step (S100) and the second treatment step (S200) are performed in a limited space, for example, fluoride discharged during the process. This should be done in an isolated plant that prevents the hydrogen from leaking out.

That is, the metal removal step (S10) to the calcium fluoride sludge collection step (S230), that is, the first treatment step (S100) and the second treatment step (S200), are isolated plants that prevent hydrogen fluoride from leaking to the outside. It is preferably carried out in the sludge extraction line containing calcium fluoride set in the inside.

On the other hand, the calcium fluoride sludge collected by the first treatment step (S100) and the second treatment step (S200) needs to be properly processed so as to be used for iron making and steel making.

For reference, since calcium fluoride needs to be used in a fixed amount when using it for iron making and iron removal, it is preferable that the calcium fluoride be molded into blocks of a predetermined amount such as briquettes.

Accordingly, the recycling method according to the present invention is a calcium fluoride block molding method, as shown in FIG. 2 , by heating the calcium fluoride-containing sludge supplied from the collection container 10 to remove HF and NH ₃ and moisture to remove calcium fluoride. A heating chamber 100 for forming powder, a binder mixing unit 200 for receiving calcium fluoride powder from the heating chamber 100 and mixing it with a binder for solidification to form a differentiated calcium molding, and a binder mixing unit 200 It can be performed by a calcium fluoride block molding line including a block molding unit 300 for forming a plurality of calcium fluoride blocks by heating and pressurizing the differentiated calcium molding formed by

Here, the calcium fluoride block forming line is a line for forming a block so as to be used for industrial purposes such as iron and steel making, and the heating chamber 100, the binder mixing unit 200 and the block forming unit 300 are appropriately disposed. .

The heating chamber 100 is configured to form calcium fluoride powder by heating the calcium fluoride-containing sludge supplied from the collection container 10 to remove HF and NH ₃ and moisture, and various configurations are possible.

For example, the heating chamber 100 has an inlet that can be opened and closed by a door so that calcium fluoride-containing sludge can be introduced by the collection container 10, and after removing impurities (HF and NH ₃ and moisture), calcium fluoride It may be composed of a chamber in which an outlet for discharging the powder is formed at the lower side.

At this time, in the heating chamber 100, an impurity removal process is performed in a closed state to recover moisture and hydrogen fluoride evaporated during heating, and an exhaust port is coupled so that the evaporated moisture and hydrogen fluoride are discharged and recovered.

The exhaust port is an exhaust port through which evaporated moisture and hydrogen fluoride are discharged, and is connected to an exhaust pipe to which a scrubber for removing hydrogen fluoride, which is a harmful substance, is coupled.

The scrubber is a configuration for discharging water vapor to the outside after removing hydrogen fluoride, and various configurations are possible.

Meanwhile, in the heating chamber 100 , calcium fluoride is solidified during heating, which may interfere with block forming to be described later, and a stirring unit may be installed therein.

The stirring unit, the rotational shaft in the axial direction is coupled to the heating chamber 100 and rotates in a state in which calcium fluoride-containing sludge is contained therein so that calcium fluoride sludge can be formed into powdery calcium fluoride when heated.

Here, the average particle size (SIZE) of the calcium fluoride preferably has a size of 1 mm or less.

Meanwhile, the heating chamber 100 may have a rotary kiln structure so that the input, drying, and discharge of calcium fluoride-containing sludge can be performed in a series of processes.

Specifically, the heating chamber 100, as shown in FIG. 4, is installed in the horizontal direction, an inlet 111 for inputting calcium fluoride-containing sludge is formed on one side of the upper part, and the calcium fluoride-containing sludge is discharged at the lower part. A cylindrical cylinder 110 having an outlet 112 for It may be composed of

The cylindrical cylinder 110 is installed in the horizontal direction, an inlet 111 for input of calcium fluoride-containing sludge is formed on one side of the upper part, and an outlet 112 for discharging calcium fluoride-containing sludge is formed at the bottom. configuration is possible.

For example, the cylindrical cylinder 110 is a configuration that forms a space for putting calcium fluoride-containing sludge therein and forms a space for heating, and has various configurations depending on the formation structure of the inlet 111 and the outlet 112 . This is possible.

Here, when calcium fluoride-containing sludge is introduced through the inlet 111, the outlet 112 is maintained in a closed state, both the outlet 112 and the inlet 111 are closed during heating, and the outlet 112 is closed during Chinese cabbage. Sludge containing calcium fluoride from which hydrogen fluoride has been removed by opening may be discharged to the outside.

On the other hand, the cylindrical cylinder 110, a heating heater 141 may be installed on the outer peripheral surface so that the moisture and hydrogen fluoride contained in the calcium fluoride-containing sludge injected therein can be discharged to the outside by heating.

The heating heater 141 is a configuration installed on the outer circumferential surface of the cylindrical cylinder 110 so that the moisture and hydrogen fluoride contained in the calcium fluoride-containing sludge injected therein can be discharged to the outside by heating, and various configuration is possible.

For example, the heating heater 141 may be configured as a planar heating heater, and a heat insulating member may be installed on the outside of the heating heater 141 to prevent heat from being emitted to the outside.

On the other hand, the cylindrical cylinder 110, the screw 130 for moving the calcium fluoride-containing sludge introduced through the inlet 111 by rotation in the longitudinal direction may be installed in the longitudinal direction.

The screw unit 130 is configured to move in the longitudinal direction the calcium fluoride-containing sludge introduced through the inlet 111 by rotation. It may include a rotating drive shaft portion 131 and a screw portion 132 installed on the outer circumferential surface of the drive shaft portion 131 .

Meanwhile, in order to increase the heating effect of the calcium fluoride-containing sludge injected into the cylindrical cylinder 110, a heating means for heating the driving shaft part 131 may be additionally provided inside the driving shaft part 131 .

The heating means is a configuration installed inside the driving shaft part 131 to heat the driving shaft part 131 in order to increase the heating effect of the calcium fluoride-containing sludge injected into the cylindrical cylinder 110, and various configurations are possible. Do.

For example, the heating means may be configured as a flow path through which a high-temperature fluid flows inside the driving shaft unit 131 , or may be configured as an electric heater installed therein.

Meanwhile, the gas evaporated inside the cylindrical cylinder 110 may be discharged to the outside through the bar scrubber 160 containing harmful gas such as hydrogen fluoride.

Here, when the heating means is configured as a flow path through which a high-temperature fluid flows inside the driving shaft part 131 , the gas evaporated from the inside of the cylindrical cylinder 110 is reintroduced to heat the inside of the cylindrical cylinder 110 , and heat is recycled. can do.

And the gas that has passed through the scrubber 160 may be discharged to the outside after moisture is removed through the strainer.

The binder mixing unit 200 is configured to receive calcium fluoride powder from the heating chamber 100 and mix it with a binder for solidification to form a differentiated calcium molded product, and various configurations are possible.

For example, the binder mixing unit 200 may include a container in which the calcium fluoride powder and the binder are contained, and a stirring part installed in the container to stir the calcium fluoride powder and the binder by rotation.

On the other hand, the binder mixed with the calcium fluoride powder is blended in a ratio sufficient to form a calcium fluoride block, which will be described later, and the physical properties of the binder can minimize impurities remaining after the block forming step (S350). This is preferable.

For example, the binder may be used by mixing an organic binder such as starch or starch powder tapioca and an inorganic binder such as sodium silicate or caustic soda.

The block molding unit 300 is a configuration for forming a plurality of calcium fluoride blocks by heating and pressurizing the differentiated calcium molding formed by the binder mixing unit 200, and various configurations are possible.

For example, as shown in FIG. 3 , the block forming unit 300 includes a pair of cylinder members 310 in which a plurality of block forming grooves 320 are formed on an outer circumferential surface facing each other and a heating heater is built in. may include

A plurality of block molding grooves 320 are formed on the outer peripheral surface of the pair of cylinder members 310 to face each other, and block molding grooves 320 formed on the outer peripheral surface of the cylinder member 310 to face each other are formed in pairs. As a cylinder member for forming a block forming space 321 for forming a calcium block, the rotating shaft may be installed horizontally.

Meanwhile, in the cylinder member 310, a heater capable of heating to an appropriate temperature to form a calcium fluoride block by utilizing the block forming space 321 is installed therein.

The heater is configured to heat to an appropriate temperature to form a calcium fluoride block by utilizing the block formation space 321, and various configurations are possible depending on the heating method.

On the other hand, the calcium fluoride block forming line, compared to the calcium fluoride-containing sludge extraction line during the process, emits a very small amount of harmful substances to a level that can be discharged to the outside without special treatment. This is preferable.

In particular, when the calcium fluoride block forming line is installed inside a plant where expensive costs are invested, the cost of reprocessing the process wastewater rapidly increases by increasing the equipment cost, whereas the calcium fluoride block forming line is separated from the calcium fluoride-containing sludge extraction line. It is possible to reduce the reprocessing cost of process wastewater by installing it in a separate space spatially separated.

Furthermore, the calcium fluoride-containing sludge extraction line is performed by a subject performing the hydrogen trifluoride manufacturing process, including a process for discharging harmful substances, and the calcium fluoride block molding line may be discharged to the outside without special treatment. Since the emission of hazardous substances is very small, it can be carried out by a separate entity independently of the calcium fluoride-containing sludge extraction line.

On the other hand, the calcium fluoride block forming line having the above configuration, as shown in FIG. 1, is a calcium fluoride block forming method, wherein the collection container 10 containing calcium fluoride-containing sludge is fluoridated by the sludge collecting step (S230). A transfer step (S310) of transferring from the calcium-containing sludge extraction line to the calcium fluoride block forming line; a sludge supply step (S320) of supplying calcium fluoride-containing sludge into the heating chamber 100 from the collection container 10 transferred to the calcium fluoride block forming line; A heating step of heating the calcium fluoride-containing sludge supplied from the collection container 10 in a state in which the heating chamber 100 is isolated from the outside to remove HF and NH ₃ and moisture to form a calcium fluoride powder (S330); A binder mixing step (S340) of receiving calcium fluoride powder from the heating chamber 100 and mixing it with a binder for solidification to form a differentiated calcium molded product; It may include a block molding step (S350) of forming a plurality of calcium fluoride blocks by heating and pressurizing the differentiated calcium molding formed by the binder mixing unit 200 .

The transfer step (S310) is a step of transferring the collection container 10 containing the calcium fluoride-containing sludge from the calcium fluoride-containing sludge extraction line to the calcium fluoride block forming line by the sludge collecting step (S230). Depending on the positional relationship between the extraction line and the calcium fluoride block forming line and the transport method of the collection container 10, it may be carried out by various methods.

For example, the calcium fluoride-containing sludge extraction line is installed in a plant in which a harmful substance discharge blocking structure is installed, and the calcium fluoride block forming line is installed outside the plant. The collection container 10 can be transported using the circulation structure of the collection container 10 .

The sludge supply step (S320) is a step of supplying calcium fluoride-containing sludge from the collection container 10 transferred to the calcium fluoride block forming line into the heating chamber 100, and may be performed by various methods.

For example, the sludge containing calcium fluoride may be supplied into the heating chamber 100 by pouring the collection container 10 through an opening formed on the upper side of the heating chamber 100 .

At this time, in the heating chamber 100, the inlet is opened and closed by the door by sealing the bar to which hydrogen fluoride is discharged when the heating step (S330), which will be described later, is performed.

In the heating step (S330), the heating chamber 100 is isolated from the outside by heating the calcium fluoride-containing sludge supplied from the collection container 10 to remove HF and NH ₃ and moisture to form calcium fluoride powder. As a step, it may be performed by various methods.

At this time, the heating temperature of the heating chamber is aimed at removing HF and NH ₃ and moisture contained in the calcium fluoride-containing sludge _. By sequentially heating based on NH ₃ , HF, moisture can be sequentially heated.

In addition, considering that the vaporization point temperature is NH ₃ , HF, and moisture, and the vaporization point of water, that is, water is 100° C., heating to 100° C. or higher can remove NH ₃ , HF, and moisture at once.

The binder mixing step (S340) is a step of receiving calcium fluoride powder from the heating chamber 100 and mixing it with a binder for solidification to form a differentiated calcium molded product, and may be performed by the binder mixing unit 200 described above. there is.

The block forming step (S350) is a step of forming a plurality of calcium fluoride blocks by heating and pressing the differentiated calcium shaped material formed by the binder mixing unit 200, and is to be performed by the block forming unit 300 described above. can

On the other hand, the present invention having the above configuration, as described above, can be applied to all process wastewater containing hydrogen fluoride, nitrogen trifluoride (NF ₃ ) process wastewater generated in the semiconductor manufacturing process as well as the gas manufacturing process Of course, process wastewater containing heavy hydrogen fluoride can also be applied.

Since the above has only been described with respect to some of the preferred embodiments that can be implemented by the present invention, as noted, the scope of the present invention should not be construed as being limited to the above embodiments, and It will be said that the technical idea and the technical idea having its roots are all included in the scope of the present invention.

10: collection container 100: heating chamber

Claims (2)

As a process wastewater recycling method for forming calcium fluoride from process wastewater containing hydrogen fluoride,
a metal removal step of mixing the process wastewater and a preset organic solvent to extract and remove one or more metals contained in the process wastewater;
a calcium fluoride sludge forming step of forming calcium fluoride-containing sludge by adding calcium hydroxide to the process wastewater from which the metal has been removed by the metal removal step;
and a calcium fluoride sludge recovery step of separating and recovering the calcium fluoride-containing sludge formed by the calcium fluoride sludge forming step. The method according to claim 1,
a calcium fluoride stirring step of adding the calcium fluoride sludge recovered by the calcium fluoride sludge recovery step to a preset amount of water and stirring and mixing;
a residual metal removal step of extracting and removing one or more metals by mixing a predetermined organic solvent with the water in which the calcium fluoride-containing sludge is added;
The process wastewater recycling method further comprising a sludge collection step of extracting calcium fluoride-containing sludge by solid-liquid separation after performing the residual metal removal step and collecting it in a preset collection container (10).

Images