KR19980035866A - Recycling method of Foshan for panel cleaning and its apparatus - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for recycling hydrofluoric acid for use in a cathode ray tube panel, . In this case, a precipitant such as sodium carbonate or caustic soda is added to the reuse tank (1) containing the waste acid without disposing the spent hydrofluoric acid, so that the chemical reaction is caused to precipitate the precipitate down and removed. The fluoric acid regenerated by the hydrofluoric acid is transferred to the fluoric acid tank 2 to clean the glass tube panel glass so that the spent fluoric acid after the cleaning treatment can be repeatedly recycled without being discarded to drastically reduce the amount of hydrofluoric acid used for cleaning the glass tube panel glass As a result, not only is it possible to drastically reduce the cost of hydrofluoric acid, The processing cost of disposal By minimizing the amount of wasted hydrofluoric acid introduced can be reduced significantly.

Description

Recycling method of Foshan for panel cleaning and its apparatus

The present invention relates to a method and apparatus for recycling hydrofluoric acid for use in a cathode ray tube panel, and more particularly, to a method for recycling fluorocarbons for a cathode ray tube panel, which comprises dissolving a rough surface of a glass into a smooth surface before attaching a phosphor or the like to the inner surface of the cathode ray tube panel glass, The present invention also relates to a method and apparatus for recycling fluorocarbons for cleaning a cathode ray tube panel in which a precipitant suspended in pulmonary hydrofluoric acid can be removed by adding a precipitant without discarding spent lung hydrofluoric acid.

The composition of the cathode ray tube panel glass consists mainly of SiO ₂ , AlO ₃ , MgO, CaO, SrO, BaO, Na ₂ O and K ₂ O. (HF) reacts with these components to generate compounds such as Na ₂ SiF ₆ , BaSiF ₆ , CaSiF ₆ , NaF, NaSO ₃ F, BaCO ₃ , CaF ₂ and Ba (OH) ₂ . .

In particular, barium Ba, sodium Na and silicon Si react with hydrofluoric acid (HF) to form Na ₂ SiF ₆ and BaSiF ₆ , which are hardly soluble in hydrofluoric acid (FH) And the amount of residual deposits increases as the cleaning operation is repeated several times. As a result, the deposit obstructs the continuous cleaning operation by blocking the hole of the cleaning nozzle, which causes considerable problems in the work process have.

In addition, when the cathode ray tube panel glass is washed using the hydrofluoric acid containing precipitate through the nozzle, the fine precipitate adheres to the panel glass, thereby deteriorating the performance of the cathode ray tube.

In order to solve this problem, in the conventional case, when the amount of the precipitate is increased and it is difficult to disperse through the nozzle, the hydrofluoric acid is disposed of and sent to the wastewater treatment plant.

However, since the concentration of hydrofluoric acid in the disposing hydrofluoric acid wastewater is about 10 to 30%, it is very inefficient in terms of economy, and the load of the wastewater treatment plant is increased by the hydrofluoric acid introduced into the wastewater treatment plant. The cost of wastewater treatment is increased, and there is a problem in that it is economically disadvantageous.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a barium fluoride which is capable of forming a precipitate again by adding a precipitant to precipitate a precipitate contained in pulmonary hydrofluoric acid so that a large amount of fluorine, The present invention aims to provide a method and apparatus for recycling fluoric acid for cleaning a cathode ray tube panel which can maximize the economic utility value by minimizing the waste of fluorine by removing ions of Ba, Si, and Na.

Figure 1 shows the X-ray diffraction diagram of the precipitate produced after washing the glass tube panel glass

2 is sodium carbonate (Na ₂ CO ₃₎ and sodium hydroxide (NaOH) X- ray diffraction of the precipitate produced after adding FIG.

3 is a block diagram of the apparatus of the present invention

Description of the Related Art [0002]

1: Reuse tank 2: Foshan tank

3: Pump 4: Conduit

5: Precipitation tank

Hereinafter, embodiments and effects of the present invention will be described in more detail with reference to the accompanying drawings.

The composition of the cathode ray tube panel glass is mainly composed of SiO ₃ , AlO ₃ , MgO, CaO, SrO, BaO, Na ₂ O and K ₂ O. (HF) reacts with these components to form precipitates such as Na ₂ SiF ₆ , BaSiF ₆ , CaSiF ₆ , NaF, NaSO ₃ F, BaCO ₃ , CaF ₂ , and Ba (OH) ₂ As described above.

Fig. 1 shows that the majority of the precipitate was BaSiF ₆ , since X-ray diffraction of the precipitate produced after washing the glass tube panel glass showed that this data was almost similar to BaSiF _{6 as} compared with the JCPDS card, which is a reference data book .

At this time, the chemical reaction formula of BaSiF ₆ production is as follows.

SiO ₂ + 6HF? SiF ₆ ^2- + SH ₂ O + 2H ⁺ ... ... ... ... ... ... ... (One)

SiF ₆ ^2- + Ba ²⁺ ? BaSiF ₆ ↓ ... ... ... ... ... ... ... ... ... ... ... ... (2)

[Table 1]

Solubility of fluorine ion compounds (g / 100 ml)

Table 2 is a quantitative analysis of the ion concentration of the elements contained in the hydrofluoric acid tank during the inoperability in the process. Sample No. 1 is a sample which is disturbed by the dispersion operation due to a large amount of sediment, Sample No. 3 shows the ion concentration at the time of washing the defective panel glass containing carbon when the defective ratio was high and Sample No. 4 shows the ion concentration at the time of washing the defective panel glass containing carbon.

When sodium carbonate (NaCO ₃ ) and caustic soda (NaOH) are added with reference to the solubility of the fluorine ion compounds in Table 1 to remove dissolved elements and precipitates, the following reaction formula is obtained from the reaction formula (1).

First, in the case of sodium carbonate (NaCO ₃ )

SiF ₆ ^2- + 2H ⁺ + Na ₂ CO ₃ ? Na ₂ SiF ₆ ↓ + 2 ₂ H + CO ₃ ... ... ... ... ... ... ... ... (3)

Ba ²⁺ + H ₂ O + CO → BaCO ₃ ↓ + 2H ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... (4)

In the case of caustic soda (NaOH)

SiF ₆ ^2- + ² NaOH → Na ₂ SiF ₆ ↓ + 2OH ^- ... ... ... ... ... ... ... ... ... ... ... ... (5)

Ba ²⁺ + 2OH ^- ? Ba (OH) ₂ ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... (6)

to be.

[Table 2]

Ion concentration of elements contained in a hydrofluoric acid tank during inoperability in the process

Figure 2 shows the results of X-ray diffraction of precipitates formed after the addition of sodium carbonate (Na ₂ CO ₃ ) and caustic soda (NaOH). This data is similar to Na ₂ SiF _{6 as} a result of comparative analysis with the JCPDS card, It can be seen that most of the precipitate is Na ₂ SiF ₆ .

At this time, it is possible to determine the most appropriate addition amount from the analysis results of the coagulation speed of the precipitate and the elements remaining in the hydrofluoric acid solution when sodium carbonate (Na ₂ CO ₃ ) and caustic soda (NaOH) are added in an equivalent ratio, (Na ₂ CO ₃ ) and caustic soda (NaOH), the concentrations of the remaining elements are similar but the concentration of barium ions is smaller when sodium carbonate is added and the rate of dissolution in the hydrofluoric acid solution is also faster Therefore, it is better.

That is, caustic soda (NaOH) is sold in a granular form, so it is disadvantageous from the economical point of view because the dissolution rate is slower and the price is higher than that of sodium carbonate (Na ₂ CO ₃ ).

Briefly, chemical reactions are induced using sodium carbonate (Na ₂ CO ₃ ) or caustic soda (NaOH), a precipitant, to remove precipitated suspended solids in the pyrogenic acid generated by washing the cathode ray tube glass with hydrofluoric acid (HF) (Na), silicon (Si), and barium (Ba), which are the elements that generate precipitates, and at the same time generate Na ₂ SiF ₆ and BaCO ₃ that are poor in resistance. If a small amount of hydrofluoric acid at a suitable concentration (usually around 60%) is adjusted to a proper concentration in the residual fluoric acid, the lung fluoric acid to be discarded after cleaning the glass tube panel glass can be reused.

Fig. 3 is a diagram showing the structure of the apparatus of the present invention. Fig. 3 is a schematic view showing the structure of the apparatus of the present invention. A pump 3 for forcibly introducing pulmonary hydrofluoric acid generated from the hydrofluoric acid tank 2 into the recycling tank 1 and a recycle tank 1 for discharging the hydrofluoric acid generated from the hydrofluoric acid tank 2 to the recycling tank 1, And a sedimentant charging tank 5 for containing a sediment agent.

In the above, plastic materials which can withstand hydrofluoric acid are most suitable for the reuse tank 1, the hydrofluoric acid tank 2 and the conduit 4, the pump 3 uses an acid-resistant pump capable of withstanding acid, The bottom surface of the sludge (1) is inclined for effective removal of the settled sludge, and the upper surface is made of transparent plastic so that the settling state can be confirmed.

In addition, the precipitant input tank 5 can be configured not only manually but also as a special control circuit, so that the dosage and the dosing interval can be automatically adjusted.

When 1% of a precipitant such as sodium carbonate or caustic soda is added to the reusing tank 1 having the above-described waste acid and the mixture is allowed to stand for 30 minutes without stirring, a chemical reaction as shown in the above formulas (1) to (6) The hydrofluoric acid (HF), which is not used for the chemical reaction in the liquid fluorine, is regenerated for recycling.

In this way, after the chemical reaction is completed, the hydrofluoric acid regenerated by the action of the pump 3 is moved to the hydrofluoric acid tank 2 to clean the cathode-ray tube panel glass. do.

Hereinafter, specific examples will be described by taking samples of sample Nos. 1 to 4 of Table 2.

[Example 1]

(Na ₂ CO ₃ ) and caustic soda (NaOH) were added to the sample for the purpose of recycling the sample No. 1, which is a cause of obstructing the operation by blocking the nozzle hole when dispersing in the panel glass because the concentration of the hydrofluoric acid is high but the amount of the precipitate is large. ) Was added at an equivalent ratio to obtain the results of Table 3 and Table 4 after the chemical reaction.

As shown in Table 3, as the concentration of fluorine was decreased from 304,000 ppm (30.4%) to that of sodium carbonate (Na ₂ CO ₃ ), the concentration of silicon (Si) decreased sharply at 116,000 ppm, Showed a gradual decline at 19,200 ppm. As the amount of sodium carbonate (Na ₂ CO ₃ ) is increased, the amount of sodium (Na) is increased but the concentration of fluorine (F) and silicon (Si) ions is also decreased.

It can be seen that these ions form a Na ₂ SiF ₆ compound and precipitate. When the barium (Ba) concentration in the sample is 300.4 ppm as shown in Table 2, but when 2 g of sodium carbonate (Na ₂ CO ₃ ) is added, it is not shown in Table 3, but it decreases to 70.14 ppm.

[Table 3]

The concentration of sodium carbonate (NaCO)

On the other hand, Table 4 is a illustrates a closed HF of the element concentration in accordance with the addition amount of caustic soda (NaOH), fluorine (F), silicon (Si), sodium (Na) decreased symptoms of ions of sodium carbonate (Na ₂ CO ₃₎ It can be seen that the same phenomenon as the case is shown.

Table 5 shows the results of practical application of 2 g, 4 g, and 6 g of sodium carbonate (Na ₂ CO ₃ ), which is considered to be an optimal condition, to the pulmonary hydrofluoric acid containing BaSiF ₆ precipitate. .

[Table 4]

The concentration of elemental elements in the pyroclastic acid by addition of caustic soda (NaOH)

Table 6 sodium carbonate in order to know the sedimentation rate of the added amount of (Na ₂ CO ₃₎ sodium carbonate to the results of the measurement of the sedimentation height of the pulmonary hydrofluoric time that includes the BaSiF ₆ precipitate applying supernatant from the actual (Na ₂ CO ₃₎ 2g, 4g, and 6g were added, and after 20 seconds of stirring, the sedimentation height was measured according to the standing time.

[Table 5]

The concentration of the element based on the amount of sodium carbonate (Na ₂ CO ₃ ) added

In the case of the pulmonary hydrofluoric acid supernatant containing no BaSiF ₆ , almost all of it precipitated within 5 minutes. In practical application, it precipitated within 5 minutes at 2g, and within 10 minutes at 4g and 6g.

These results indicate that the addition of 2, 4, and 6 g of sodium carbonate significantly reduces impurities and does not significantly reduce the concentration of fluorine, and that sedimentation of the precipitate is almost complete within 10 minutes.

As a result, when 2 g of sodium carbonate (Na ₂ CO ₃ ) is added, the ion concentration of fluorine is 232,000 ppm (23.2%), which is the final amount of fluorine that can be recycled. Therefore, when the proper concentration is adjusted to 60% hydrofluoric acid through the apparatus of the present invention, it can be recycled.

[Table 6]

The sedimentation rate (unit: ml) according to the addition amount of sodium carbonate (Na ₂ CO ₃ )

[Example 2]

In order to recycle the pulmonary hydrofluoric acid during the regular replacement operation after the cathode ray tube panel glass was washed for 24 hours, the sample of Sample No. 2 was used. It was confirmed that the addition of sodium carbonate (Na ₂ CO ₃ ) The concentrations are shown in Table 7.

When 2 g of sodium carbonate was added, the fluorine (F) concentration was changed from 213,000 ppm (21.3%) to 183,000 ppm (18.3%), the silicon concentration was changed from 12,065 ppm to 6,860 ppm, Lt; / RTI >

[Table 7]

Ion Concentration in Pulverized Acid Depending on the Addition of Sodium Carbonate (Na ₂ CO ₃ )

The similar tendency was observed for 1.0 g, 3.0 g and 4.0 g, and the silicon (Si) causing the precipitation tended to decrease as the amount of sodium carbonate (Na ₂ CO ₃ ) was increased , The amount of sodium (Na) does not show much change.

Table 8 shows the settling rate of the precipitate according to the addition amount of sodium carbonate (Na ₂ CO ₃ ), which was also obtained by measuring the settling height according to Example 1 and the standing time.

[Table 8]

The sedimentation rate (unit: ml) according to the addition amount of sodium carbonate (Na ₂ CO ₃ )

It can be seen that sedimentation of sediment is almost completed within 10 minutes and that the amount of precipitate increases as the amount of sodium carbonate (Na ₂ CO ₃ ) increases and the decrease of silicon (Si) Indicating that Na ₂ SiF ₆ is formed.

As a result, when 2 g of sodium carbonate (Na ₂ CO ₃ ) is added, the ion concentration of fluorine is 183.000 ppm (18.3%), which is the final amount of fluorine that can be recycled. Therefore, if the concentration of 60% hydrofluoric acid is adjusted through the apparatus of the present invention, there is no problem in washing the panel glass for 24 hours, and even after 24 hours of use, it can be regenerated and used continuously.

[Example 3]

The sample No. 4 in Table 2 is used as a sample. It is in a floating state that many solids and impurities are not scattered in the non-annealed cool which is used to clean the glass of the cathode ray tube panel and to clean the glass after the phosphor and graphite are coated. Since the amount of impurities such as a carbon component, a phosphor component, Ba ₂ SiF ₆ , Si, Na, and Ba is large in hydrofluoric acid after removing the adherend attached to the panel glass, sodium carbonate (Na ₂ CO ₃ ) was added and the result of the analysis was as shown in Table 9. The change in the concentration of fluorine (F), silicon (Si), and sodium (Na) when 1.0 to 3.0 g of sodium carbonate (Na ₂ CO ₃ ) is added to pulmonary hydrofluoric acid is almost the same as that in Examples 1 and 2 .

When 2 g of sodium carbonate is added, the concentration of fluorine (F) does not change much and the concentration of silicon (Si) decreases to more than half but the concentration of sodium (Na) increases.

[Table 9]

Ion Concentration in Pulverized Acid Depending on the Addition of Sodium Carbonate (Na ₂ CO ₃ )

The sedimentation rate of the precipitate was measured while increasing the addition amount of sodium carbonate (Na ₂ CO ₃ ) in the same manner as in Example 1 and Example 2, and the results are shown in Table 10.

However, unlike Example 1 and Example 2, the pulverized boric acid containing carbon particles was turbid to such an extent that the turbidity before sedimentation could not be measured due to the influence of the carbon particles and the phosphor, but after 10 minutes, the fine carbon component was floating, After 20 minutes, the suspended matter also completely settled. And the amount of sediment is more than that of Example 1 and Example 2. [

Since the fluorine ion concentration is 161,000 ppm (16.1%) under the condition that 2 g of sodium carbonate (Na ₂ CO ₃ ) is added to the pulmonary hydrofluoric acid and the solution is allowed to stand for 20 minutes, this is the final concentration of fluorine which can be recycled. Even when recycled, no defects were found in the products of the cathode-ray tube, and the amount of fluorine used was drastically reduced.

[Table 10]

The sedimentation rate (unit: ml) according to the addition amount of sodium carbonate (Na ₂ CO ₃ )

The effects obtained by the present invention having the above-described embodiments and actions can be effectively utilized by removing the precipitating substance by using a precipitant, which is discarded after use, As a result, it is possible to greatly reduce the cost of hydrofluoric acid, and to minimize the disposal amount of hydrofluoric acid introduced into the wastewater treatment plant, thereby significantly reducing the disposal cost for disposal .

Claims (2)

In order to remove precipitated suspended solids in the pulverized boric acid generated when the glass tube panel is washed with hydrofluoric acid (HF), sodium carbonate (Na ₂ CO ₃ ) or caustic soda (NaOH), which is a precipitant, (Na), silicon (Si), and barium (Ba), and at the same time, Na ₂ SiF ₆ and BaCO ₃ , which are poor in solubility, are produced and precipitated and then removed. A method for recycling fluorocarbons for cleaning a cathode ray tube panel characterized in that a small amount of an appropriate concentration of hydrofluoric acid is added to adjust the concentration of the fluorocarbons to reuse the spent fluorocarbons after cleaning the cathode ray tube panel glass. A reclamation tank for reclaiming the spent hydrofluoric acid introduced from the pump by adding a precipitant to the reclaiming tank and re-introducing it; a plurality of hydrofluoric acid tanks for cleaning the glass tube panel glass communicated by the reclamation tank and the conduit; A pump for forcibly introducing the recycle tank into the re-use tank, and a sedimentation tank for storing the precipitant to be introduced into the recycle tank.