TWI606975B - Treating and Recycling Method of Fluorine Containing Dust - Google Patents

Description

Fluorine dust collection ash treatment and recovery method

The invention relates to a method for treating and recovering fluorine-containing dust ash, and is particularly suitable for dust collecting ash generated by a flat panel display (TFT-LCD) process for producing a high purity fluoroantimonate.

In the electronic industry, flat panel display (TFT-LCD) glass substrate film process is based on the principle of chemical vapor deposition, and the gas such as methane, nitrogen trifluoride and ammonia is introduced into the chemical vapor deposition (CVD) machine. It is deposited on a glass substrate under conditions of temperature, pressure, and the like to form an insulating layer. The gas that is not completely reacted is treated by the burner of the process to form suspended particles, and then collected by the bag dust collector of the exhaust gas treatment program to become dust collecting ash. The dust collecting ash component is mainly ammonium fluoroantimonate and dioxide. Hey, the country generally treats it as waste, but it still causes environmental problems.

The invention provides a method for treating and recovering fluorine-containing dust ash, which is particularly suitable for collecting dust generated by a flat panel display (TFT-LCD) process, and is used for manufacturing a high purity fluoroantimonate, including a dissolution section, The dust-collecting ash of ammonium fluoride citrate and cerium oxide is mixed with water to dissolve the water-soluble ammonium fluoroantimonate. The first separation section, the turbid solution obtained in the dissolution section, is subjected to solid-liquid separation to obtain a clear solution of ammonium fluoride citrate and insoluble solid cerium oxide. The replacement section, the ammonium fluoroantimonate solution obtained in the first separation stage, is added with a salt containing sodium or potassium to produce a fluoroantimonate precipitate of sodium fluoroantimonate or potassium fluoroantimonate. In the second separation stage, the turbid solution obtained in the replacement section is subjected to solid-liquid separation to obtain sodium fluoroantimonate or potassium fluoroantimonate.

The method of the invention can recover the fluorine-containing dust ash and obtain the fluoroantimonate with high purity to achieve the purpose of waste recycling and reuse.

According to the drawings, the present invention provides a method for treating and recovering fluorine-containing dust ash (as shown in FIG. 1), and the program steps include a dissolution section S1, a first separation section S2, a replacement section S3, and a second separation section. S4, where:

Dissolving the segment S1, mixing the fluorine-containing ammonium citrate ((NH4)2SiF6) with the dust ash of cerium oxide (SiO2) and water, and dissolving the soluble ammonium fluoroantimonate in water to obtain a first turbid solution.

In the first separation section S2, the turbid solution obtained in the dissolution section is subjected to solid-liquid separation to obtain a clear solution of ammonium fluoride citrate and insoluble powdery cerium oxide.

Substituting section S3, a clear solution of ammonium fluoride citrate obtained in the first separation stage, adding sodium or potassium-containing salts to produce sodium fluorophthalate (Na2SiF6) or potassium fluoroantimonate (K2SiF6) fluoroantimonate a precipitate and a second turbid solution.

In the second separation section S4, the second turbid solution obtained in the replacement section is subjected to solid-liquid separation to obtain sodium fluoroantimonate or potassium fluoroantimonate fluoroantimonate.

In the method of the present invention, in the dissolution section S1, the dust-collecting ash of ammonium fluoride citrate and cerium oxide is mixed with water, and the water dissolves the soluble ammonium fluoroantimonate. The solubility of ammonium fluoroantimonate in water is 186 g/L at 20 ° C and 250 g / L at 30 ° C. The solubility of water exceeds the solubility of ammonium fluorocarbonate in water, specifically, the capacity and dust collection of water. When the mass ratio of ash is between 4.6:1 and 2.3:1, the ammonium fluoroantimonate in the solid dust ash can be completely dissolved and the first mixed solution can be obtained. The water temperature during dissolution is not particularly limited, but the temperature is higher. The higher the solubility.

In the first separation section S2, the first turbid solution obtained in the dissolution section is subjected to solid-liquid separation to obtain a clear solution of ammonium fluoride citrate and water-insoluble cerium oxide. The solid-liquid separation device used, such as a centrifuge or a filter press, separates the water-insoluble ceria from the first turbid solution and obtains a clear solution of ammonium fluoride citrate, and the separated cerium oxide, It can be washed with water, the impurities are washed away, and cerium oxide is obtained, sold directly or dried and sold.

In the method of the present invention, in the replacement section S3, the clear solution of the ammonium fluoride-containing ammonium citrate obtained in the first separation stage is added with a salt containing sodium or potassium to produce a fluoroantimonate precipitate of sodium fluoroantimonate or potassium fluoroantimonate. . The salt containing sodium or potassium may be sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), sodium hydrogencarbonate (NaHCO ₃ ), potassium hydrogencarbonate (KHCO ₃ ), sodium sulfate (Na ₂ SO _{4 ).} ), potassium sulfate (K ₂ SO ₄ ), sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO ₃ ), potassium nitrate (KNO ₃ ), and the like, and the purity thereof is not particularly limited. It is preferably more than 95 wt.%, and the type to be added is not particularly limited, and it may be added in a liquid state in a solid state or in addition to water.

In the method of the present invention, in the replacement section S3, a salt containing sodium or potassium is reacted with ammonium fluoroantimonate ((NH ₄ ) ₂ SiF ₆ ) in a solution to produce sodium fluorophthalate (Na ₂ SiF ₆ ) or fluoroantimonic acid. The precipitate of potassium (K ₂ SiF ₆ ) and the second turbid solution, the theoretical molar ratio of sodium (Na) or potassium (K) to fluoroantimonate (SiF ₆ ^-2 ) is 2: 1, the molar ratio at the time of reaction is not In particular, the high molar ratio means that the sodium or potassium-containing salt is added in a large amount, which is unfavorable for the operation cost. If the molar ratio is too low, the sodium or potassium-containing salt is added in a small amount, and the unreacted fluoroantimonic acid has a large amount. The recovery amount of sodium fluoroantimonate (Na ₂ SiF ₆ ) or potassium fluoroantimonate (K ₂ SiF ₆ ) is reduced.

In the second separation section S4, the second turbid solution obtained in the replacement section is subjected to solid-liquid separation to obtain a sodium fluoroantimonate or a potassium fluoroantimonate fluoroantimonate, and a solid-liquid separation device can be used. For example, a centrifuge, a filter press, etc., the sodium fluoroantimonate or potassium fluoroantimonate precipitate is separated from the second turbid solution, and the separated sodium fluoroantimonate or potassium fluoroantimonate can be washed with water to wash the impurities. Directly sold, or dried to obtain a product with high purity for sale. In addition, sodium fluoroantimonate or potassium fluoroantimonate can be isolated to obtain an ammonium-containing salt solution, which can be used for other purposes (for example, sodium chloride solution can be obtained by adding sodium chloride to the ammonium-containing salt solution, and further concentrated. Crystallization can be obtained as an ammonium chloride product as a battery, battery, ammonium salt, precision casting, tanning, electroplating, photographic or adhesive, etc.).

The present invention is based on the above-described method for treating and recovering the fluorine-containing dust ash, and is assumed to be an example under the conditions of the method described, but it should be understood that the present invention is not limited by the conditions and contents described in the specific embodiments:

Example 1: A process for producing dust from a flat panel display (TFT-LCD) process, the composition of which is as follows: 68.5% ammonium fluoroantimonate ((NH ₄ ) ₂ SiF ₆ ), 29.5% cerium oxide (SiO ₂ ), And 2.0% water (H ₂ O), in a 5 liter mixing tank, add 3,560 ml of water, pour 1,000 grams of dust ash, stir for 1 hour and then stop to get the first turbid solution, due to dioxide矽 is insoluble in water, so after removing the first turbid solution in the barrel for filtration, the obtained wet cerium oxide is washed with 700 ml of a clear solution of ammonium fluoride citrate, and the wet cerium oxide is washed with water. And the washing liquid of the cleaned cerium oxide is mixed with the clear solution of ammonium fluoride citrate, and finally, 4,445 grams of a clear solution of ammonium fluoride citrate and 800 g of wet cerium oxide are obtained, and a clear solution of ammonium fluoride citrate is analyzed. The content of ammonium fluoroantimonate ((NH ₄ ) ₂ SiF ₆ ) was measured to be 13.9%. The clear solution of ammonium fluoride citrate was transferred into a stirring tank having a volume of 5 liters, and while stirring, slowly adding 406 g of salt (NaCl), stirring for 1 hour, stopping to obtain the second turbid solution, and taking out the second inside the barrel. The turbid solution was filtered, and the obtained wet sodium fluoroantimonate and 500 ml of an ammonium-containing salt solution were washed with water, and then dried in an oven at 100 ° C for 2 hours to obtain 620 g of dried. Sodium fluoroantimonate, the purity of sodium fluoroantimonate was determined to be 98.1%.

Example 2: A process from a flat panel display (TFT-LCD) produces dust collecting ash having the following composition: 68.5% ammonium fluoroantimonate ((NH ₄ ) ₂ SiF ₆ ), 29.5% cerium oxide (SiO ₂ ), And 2.0% water (H ₂ O), in a 5 liter mixing tank, add 3,600 ml of water, pour 1,000 grams of dust ash, stir for 1 hour and then stop to get the first turbid solution, due to dioxide矽 is insoluble in water, so after removing the first turbid solution in the barrel for filtration, the obtained wet cerium oxide and 700 ml of a clear solution of ammonium fluoride citrate are used to wash the wet cerium oxide with water. And the washing liquid of the cerium dioxide cleaning and the clear solution of ammonium fluoride citrate are combined, and finally, 4,510 grams of a clear solution of ammonium fluoride citrate and 780 grams of wet cerium oxide are obtained, and a clear solution of ammonium fluoride citrate is analyzed. The content of ammonium fluoroantimonate ((NH ₄ ) ₂ SiF ₆ ) was measured to be 13.5%. The clear solution of the ammonium fluoride citrate was transferred into a stirring tank having a volume of 5 liters, and while stirring, slowly adding 485 g of sodium sulfate (Na ₂ SO ₄ ), stirring for 1 hour, stopping to obtain the second turbid solution, and taking out the barrel. The second turbid solution was filtered, and the obtained wet sodium fluoroantimonate and 500 ml of an ammonium-containing salt solution were washed with water, and then dried in an oven at 100 ° C for 2 hours to obtain 615 g. The dried sodium fluoroantimonate was analyzed and found to have a purity of 98.2%.

Example 3: A process from a flat panel display (TFT-LCD) produces dust collecting ash having the following composition: 70.3% ammonium fluoroantimonate ((NH ₄ ) ₂ SiF ₆ ), 28.5% cerium oxide (SiO ₂ ), And 1.2% water (H ₂ O), in a 5 liter mixing tank, add 3,600 ml of water, pour 1,000 grams of dust ash, stir for 1 hour and then stop to get the first turbid solution, due to dioxide矽 is insoluble in water, so after the first turbid solution in the barrel is filtered, the obtained wet cerium oxide is washed with water in 700 ml of water, and the washing liquid of cerium oxide is washed and contained. The clear solution of ammonium fluoroantimonate was mixed, and finally, 4,490 g of a clear solution of ammonium fluoride citrate and 790 g of cerium oxide were obtained. The ammonium fluoroantimonate ((NH ₄ ) ₂ SiF was determined by analyzing the clear solution of ammonium fluoride citrate. ₆ ) The content is 14.8%. The clear solution of ammonium fluoride citrate was transferred into a stirred tank of 5 liters in volume, and while stirring, 557 grams of potassium chloride (KCl) was slowly added, and after stirring for 1 hour, the second turbid solution was stopped, and the inside of the barrel was taken out. After the second turbid solution was filtered, the obtained potassium fluoroantimonate and 500 ml of an ammonium-containing salt solution were washed with water, and then dried in an oven at 100 ° C for 2 hours to obtain 620 g of dried. Potassium fluoroantimonate, the purity of potassium fluoroantimonate was 98.3%.

The method for treating and recovering fluorine-containing dust ash of the invention can obtain high purity sodium fluoroantimonate or potassium fluoroantimonate product and cerium oxide (can be used as raw material of water glass, and can also be used as waste hydrogen fluoride solution). The use of recycled fluorine to produce fluorodecanoate raw materials), thus increasing the economic value of dust ash.

The present invention disclosed in the specification is to be considered as illustrative and not restrictive. The scope of the present invention is defined by the scope of the appended claims, and is not intended to be limited by the scope of the invention.

S1‧‧‧dissolved section

S2‧‧‧ first separation section

S3‧‧‧ replacement section

S4‧‧‧Second separation

Fig. 1 is a schematic flow chart showing a method of treating and recovering fluorine-containing dust ash according to the present invention.

The following description is merely illustrative of the basic teachings of the present invention, and the description of the components, the amount of use, the operating conditions, and other related extensions of the preferred embodiments will be explained, after reading and understanding the teachings of the present invention. Related changes are implemented in industry skills. In addition, changes in the combination of specific equipment, concentration of action, temperature of action, and the like are also within the skill of the art after reading and understanding the teachings of the present invention.

S1‧‧‧dissolved section

S2‧‧‧ first separation section

S3‧‧‧ replacement section

S4‧‧‧Second separation

Claims (4)

The invention relates to a method for treating and recovering fluorine-containing dust ash, comprising: a dissolving section, mixing the dust-collecting ash of ammonium fluoride citrate and cerium oxide with water, and the mass ratio of water capacity to dust collecting ash is between 4.6:1. Between ~2.3:1, the ammonium fluoroantimonate is dissolved in water to obtain the first turbid solution, the first turbid solution obtained in the first separation section and the dissolution section is subjected to solid-liquid separation to obtain a clear solution of ammonium fluoride citrate. In combination with the cerium oxide insoluble in water, the replacement section, sodium citrate (Na ₂ CO ₃ ) and potassium carbonate are added according to the content of ammonium fluoroantimonate in the clear solution of ammonium fluoride citrate obtained in the first separation stage. K ₂ CO ₃ ), sodium hydrogencarbonate (NaHCO ₃ ), potassium hydrogencarbonate (KHCO ₃ ), sodium sulfate (Na ₂ SO ₄ ), potassium sulfate (K ₂ SO ₄ ), sodium chloride (NaCl), potassium chloride (KCl), sodium nitrate (NaNO ₃ ), potassium nitrate (KNO ₃ ), and the like, producing a fluoroantimonate precipitate of sodium fluoroantimonate or potassium fluoroantimonate to obtain a second turbid solution, the second separation section, The second turbid solution obtained in the replacement section is subjected to solid-liquid separation to obtain sodium fluoroantimonate or potassium fluoroantimonate fluorosilicate and ammonium salt solution. The method for treating and recovering fluorine-containing dust ash according to claim 1, wherein the salt containing sodium or potassium has a purity of more than 95 wt.%, and the added form is not particularly limited, and may be solid or water-formed into a liquid state. Join. The method for treating and recovering fluorine-containing dust ash according to claim 1, wherein sodium (Na) or potassium (K) containing a salt of sodium or potassium, and fluoroantimonate (SiF ₆ ) in a waste liquid The theoretical molar ratio of ^-2 ) is 2:1. The method for treating and recovering fluorine-containing dust ash according to claim 1, wherein the fluoroantimonate separation step uses at least one solid-liquid separation device of the centrifuge and the filter press to separate the fluoroantimonic acid. Sodium or potassium fluoroantimonate.