A hydrofluoric acid arsenic removal device and process

Abstract

The present invention discloses a hydrofluoric acid arsenic removal device and process, including a hydrofluoric acid crude product heating tank, a regulating valve, an intake flowmeter, a reboiler, a first-stage condenser, a circulating spray pump, a spray tower, a low-boiling-point exhaust port, a sampling port, and a hydrofluoric acid finished product collection tank. The hydrofluoric acid crude product heating tank is connected to the spray tower, and a regulating valve and an intake flowmeter are provided on the pipeline between the hydrofluoric acid crude product heating tank and the spray tower. In the present invention, the arsenic-containing hydrofluoric acid is vaporized and then introduced into the spray tower with an oxidant for spray contact reaction. The arsenic is oxidized to arsenic pentafluoride with a low boiling point and discharged from the top of the condenser. After the oxidant refluxes, it returns to the spray tower. The arsenic content in the hydrofluoric acid after arsenic removal is 0-10 ppt, and the oxidant content is 0-10 ppt, fully meeting the requirements of electronic-grade hydrofluoric acid. Moreover, the oxidant content in the hydrofluoric acid is very small, meeting more stringent usage requirements.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and in particular to an arsenic removal device and process for hydrofluoric acid. Background Art

[0002] In the process of producing hydrofluoric acid, heavy metal arsenic exists in the trivalent state. Since the boiling point of trivalent arsenic is almost the same as that of hydrofluoric acid, it cannot be removed by either rectification or degassing, and it is very difficult to remove it solely by process improvement. For this reason, a new chemical removal method has been adopted, that is, by adding an oxidant such as potassium permanganate solution to anhydrous hydrogen fluoride to change its chemical composition, so that trivalent arsenic becomes pentavalent arsenic, and the boiling point of pentavalent arsenic is much higher than that of hydrofluoric acid. Therefore, it can be well removed during the rectification process. However, this method is likely to cause the residue of the oxidant, which affects the subsequent use of hydrofluoric acid, resulting in either more other impurities in the arsenic-removed hydrofluoric acid or the arsenic content can only reach the ppb level, unable to meet the requirements of electronic-grade hydrofluoric acid.

[0003] Patent CN103864018B discloses a method for removing arsenic from industrial hydrofluoric acid. This method oxidizes and removes arsenic by adding 1.45 - 1.55 times the theoretical quantitative amount of potassium permanganate to the circulating hydrofluoric acid. However, after adding the oxidant, the reaction still needs to last for 2 - 5 hours, and the hydrofluoric acid after the reaction needs to be sampled to ensure the appropriate amount of oxidant added. The process flow is cumbersome and not conducive to continuous production.

[0004] Patent CN213595885U introduces an arsenic removal device for anhydrous hydrofluoric acid. This method removes arsenic by stirring and reacting after mixing hydrofluoric acid, and then passing it into a rectification column to rectify and separate the oxidant to purify hydrofluoric acid. However, this method is also not suitable for continuous production, and there is a large amount of energy consumption during the rectification process, and there is serious entrainment at the same time. The content of the oxidant in the hydrofluoric acid product rectified at the top of the column is too high to meet the requirements of electronic-grade hydrofluoric acid. Summary of the Invention

[0005] The purpose of the present invention is to provide an arsenic removal device for hydrofluoric acid to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A hydrofluoric acid arsenic removal device, comprising a crude hydrofluoric acid heating tank, a regulating valve, an intake gas flowmeter, a reboiler, a first-stage condenser, a circulating spray pump, a spray tower, a low-boiling point exhaust port, a sampling port, and a hydrofluoric acid finished product collection tank. The crude hydrofluoric acid heating tank is connected to the spray tower, and a regulating valve and an intake gas flowmeter are provided on the pipeline between the crude hydrofluoric acid heating tank and the spray tower. Both ends of the spray tower are respectively connected to a first-stage condenser and a reboiler. The first-stage condenser is connected to a second-stage condenser through a gas-phase pipeline, and the second-stage condenser is connected to the hydrofluoric acid finished product collection tank.

[0008] As a further technical solution of the present invention: A first drain port is further connected to the crude hydrofluoric acid heating tank.

[0009] As a further technical solution of the present invention: A second drain port is further connected to the spray tower.

[0010] As a further technical solution of the present invention: A low-boiling point exhaust port is further connected to the second-stage condenser.

[0011] As a further technical solution of the present invention: A sampling port is further connected to the pipeline between the low-boiling point exhaust port and the hydrofluoric acid finished product collection tank.

[0012] As a further technical solution of the present invention: A circulating spray pump is further connected to the spray tower. One end of the circulating spray pump is connected to the bottom of the spray tower through a pipeline, and the other end is connected to the top of the spray tower 8 through a pipeline.

[0013] As a further technical solution of the present invention: The oxidant in the spray tower is a liquid oxidant, specifically at least one of a toluene solution of p-nitrotoluene, hydrogen peroxide, and a potassium permanganate solution.

[0014] As a further technical solution of the present invention: The oxidant in the spray tower is a toluene solution of nitrotoluene, and the oxidant is separated from the product by a layering method.

[0015] As a further technical solution of the present invention: Control the temperature of the top condenser of the spray tower at 40 - 70 °C.

[0016] As a further technical solution of the present invention: The control of the arsenic content in the finished hydrofluoric acid is achieved by the interlock of the on-line detection of the arsenic content and the intake gas flowmeter, and the intake gas quality is controlled: the spray volume ratio = 1:20 - 40 kg / m 3 , and the arsenic content in the finished product is controlled at 0 - 10 ppt, and the oxidant content is controlled at 0 - 10 ppt.

[0017] As a further technical solution of the present invention: control the system temperature in the spray tower at 60 - 90 °C, control the temperature of the first-stage condenser at 40 - 70 °C, control the temperature of the second-stage condenser at -10 - 10 °C. After being cooled by the first-stage condenser at the top of the spray tower, the oxidant flows back into the rectification tower. The low-boiling substances are discharged from the top of the second-stage condenser, and the hydrofluoric acid after arsenic removal is collected in the hydrofluoric acid finished product collection tank after being cooled by the condenser.

[0018] A process for removing arsenic from hydrofluoric acid. The arsenic-containing hydrofluoric acid is vaporized and then introduced into a spray tower with an oxidant for spray contact reaction to oxidize arsenic into arsenic pentafluoride with a low boiling point. The spray tower is connected to two condensers. After being cooled by the first-stage condenser, the oxidant flows back into the rectification tower. The hydrofluoric acid and low-boiling substances are discharged from the top of the first-stage condenser and then introduced into the second-stage condenser for separation. The low-boiling substances are discharged from the top of the second-stage condenser, and the hydrofluoric acid is discharged from the bottom of the second-stage condenser and then collected.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] In the present invention, the arsenic-containing hydrofluoric acid is vaporized and then introduced into a spray tower with an oxidant for spray contact reaction. After oxidizing arsenic into arsenic pentafluoride with a low boiling point, it is discharged from the top of the condenser. After the oxidant flows back, it returns to the spray tower. The arsenic content in the hydrofluoric acid after arsenic removal is 0 - 10 ppt, and the oxidant content is 0 - 10 ppt, which fully meets the requirements of electronic-grade hydrofluoric acid. The oxidant content in the hydrofluoric acid is very small, meeting more stringent usage requirements. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the main structure of a hydrofluoric acid arsenic removal device.

[0022] In the figure: 1 - hydrofluoric acid crude product heating tank, 2 - first drain port, 3 - regulating valve, 4 - intake flowmeter, 5 - reboiler, 6 - second drain port, 7 - circulating spray pump, 8 - spray tower, 9 - first-stage condenser, 10 - gas pipeline, 11 - second-stage condenser, 12 - low-boiling substance exhaust port, 13 - sampling port, 14 - hydrofluoric acid finished product collection tank. Specific Embodiments

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Refer to Figure 1, A hydrofluoric acid arsenic removal device, including a crude hydrofluoric acid heating tank 1. The crude hydrofluoric acid heating tank 1 realizes the gasification of hydrofluoric acid through jacket heating. A regulating valve 3 and an intake flowmeter 4 are connected to the top. The intake air volume is controlled by controlling the opening degree of the regulating valve 3. The gasified hydrofluoric acid is introduced into a spray tower 8 filled with a liquid oxidant. The spray tower 8 is internally filled with packing. The oxidant at the bottom is transported to the top of the spray tower through a circulating spray pump 7 for spraying to contact with the arsenic-containing hydrofluoric acid. The oxidant is cooled by a first-stage condenser 9 to achieve reflux. The reacted hydrofluoric acid and low-boiling substances are discharged from the top of the first-stage condenser 9 and enter a second-stage condenser 11. The low-boiling substances are discharged from the low-boiling substance exhaust port 12 at the top of the second-stage condenser 11. The hydrofluoric acid is collected in a hydrofluoric acid finished product collection tank 14 after being cooled by the second-stage condenser 11. A sampling port 13 is provided in front of the hydrofluoric acid finished product collection tank 14. By on-line detecting the arsenic content in the hydrofluoric acid and interlocking to control the opening degree of the regulating valve 3, the stable control or removal of the arsenic content in the hydrofluoric acid is realized.

[0025] The spray tower 8 is filled with a liquid oxidant. The bottom of the spray tower 8 is connected with a circulating magnetic pump. The contact reaction between the liquid oxidant and the arsenic-containing hydrofluoric acid is realized through spraying by the circulating spray pump 7. After the reaction, arsenic is oxidized to arsenic pentafluoride with a low boiling point and is discharged as a low-boiling substance at the top of the second-stage condenser 11.

[0026] Comparative Example 1:

[0027] Add 20 kg of HF with an arsenic content of 8 ppm and 20 g of hydrogen peroxide to a DN300 spray tower. Control the temperature of the spray tower at 90 °C through a reboiler, control the flow rate of the spray circulating pump at 10 m 3 / h, control the temperature of the first-stage condenser at 60 °C, control the temperature of the second-stage condenser at 0 °C, and extract HF at a rate of 0.5 kg / h. The obtained hydrofluoric acid has an arsenic content of 2 ppm and a hydrogen peroxide content of 1 ppb.

[0028] Comparative Example 2:

[0029] Add 20 kg of hydrogen peroxide to a DN300 spray tower. Control the temperature of the spray tower at 60 °C through a reboiler, control the flow rate of the spray circulating pump at 10 m 3 / h, control the temperature of the first-stage condenser at 50 °C, control the temperature of the second-stage condenser at 0 °C, and introduce and extract HF at a rate of 0.75 kg / h. The introduced HF has an arsenic content of 8 ppm, and the extracted HF has an arsenic content of 4 ppm and a hydrogen peroxide content of 1 ppm.

[0030] Comparative Example 3:

[0031] Add 20 kg of hydrogen peroxide to a DN300 spray tower. Control the temperature of the spray tower at 40 °C through a reboiler, control the flow rate of the spray circulating pump at 10 m 3 / h, control the temperature of the first-stage condenser at 40 °C, control the temperature of the second-stage condenser at -10 °C, introduce and extract HF at a rate of 1.0 kg / h. The arsenic content of the introduced HF is 8 ppm, the arsenic content of the extracted HF is 5 ppm, and the hydrogen peroxide content is 2 ppm.

[0032] Example 1:

[0033] Add 20 kg of hydrogen peroxide to the DN300 spray tower. Control the temperature of the spray tower at 90 °C through the reboiler, and control the flow rate of the spray circulation pump at 10 m 3 / h, control the temperature of the first-stage condenser at 60 °C, control the temperature of the second-stage condenser at 0 °C, introduce and extract HF at a rate of 0.5 kg / h. The arsenic content of the introduced HF is 8 ppm, the arsenic content of the extracted HF is 4 ppb, and the hydrogen peroxide content is 8 ppb.

[0034] Example 2:

[0035] Add 20 kg of potassium permanganate to the DN300 spray tower. Control the temperature of the spray tower at 90 °C through the reboiler, and control the flow rate of the spray circulation pump at 10 m 3 / h, control the temperature of the first-stage condenser at 60 °C, control the temperature of the second-stage condenser at 0 °C, introduce and extract HF at a rate of 0.5 kg / h. The arsenic content of the introduced HF is 8 ppm, the arsenic content of the extracted HF is 2 ppb, and the potassium permanganate content is 6 ppb.

[0036] Example 3:

[0037] Add 20 kg of toluene solution of p-nitrotoluene to the DN300 spray tower. Control the temperature of the spray tower at 80 °C through the reboiler, and control the flow rate of the spray circulation pump at 10 m 3 / h, control the temperature of the first-stage condenser at 60 °C, control the temperature of the second-stage condenser at 0 °C, introduce and extract HF at a rate of 0.3 kg / h. The arsenic content of the introduced HF is 8 ppm, the arsenic content of the extracted HF is 8 ppb, and the p-nitrotoluene content is 0 ppb.

[0038] Example 4:

[0039] Add 20 kg of hydrogen peroxide to the DN300 spray tower. Control the temperature of the spray tower at 90 °C through the reboiler, and control the flow rate of the spray circulation pump at 10 m 3 / h, control the temperature of the first-stage condenser at 70 °C, control the temperature of the second-stage condenser at 10 °C, introduce and extract HF at a rate of 0.25 kg / h. The arsenic content of the introduced HF is 8 ppm, the arsenic content of the extracted HF is 2 ppb, and the hydrogen peroxide content is 6 ppb.

[0040] Example 5:

[0041] Add 20 kg of toluene solution of p-nitrotoluene to the DN300 spray tower. Control the temperature of the spray tower at 60 °C through the reboiler, and control the flow rate of the spray circulation pump at 10 m3 / h, control the temperature of the first-stage condenser at 40°C, control the temperature of the second-stage condenser at -10°C, introduce and extract HF at a rate of 0.3 kg / h. The arsenic content of the introduced HF is 8 ppm, the arsenic content of the extracted HF is 5 ppb, and the toluene solution content of p-nitrotoluene is 0 ppb.

[0042] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

[0043] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment have been appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A hydrofluoric acid arsenic removal process, characterized in that, After vaporizing arsenic-containing hydrofluoric acid and introducing it into a spray tower with an oxidant for spray contact reaction, arsenic is oxidized to arsenic pentafluoride with a low boiling point; the spray tower is connected to two condensers. The oxidant is cooled through the first condenser to achieve reflux. Hydrofluoric acid and low-boiling substances are discharged from the top of the first condenser and then introduced into the second condenser for separation. The low-boiling substances are discharged from the top of the second condenser, and the hydrofluoric acid is discharged from the bottom of the second condenser and then collected; The oxidant in the spray tower is a liquid oxidant, specifically at least one of a toluene solution of p-nitrotoluene, hydrogen peroxide, and a potassium permanganate solution; The system temperature in the spray tower is 60 - 90 °C, the temperature of the first-stage condenser is 40 - 70 °C, and the temperature of the second-stage condenser is -10 - 10 °C. Control the intake air quality: spray volume = 1:20 - 40 kg / m 3 .

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