KR20120010637A - Method and apparatus for recovering hexafluorosilicic acid from manufacturing process of phosphoric acid - Google Patents

Abstract

PURPOSE: A method and an apparatus for collecting fluorosilicic acid in a phosphoric acid manufacturing process are provided to improve the collecting efficiency of fluorosilicic acid by continuously passing waste gas through a multi-staged vortex scrubber and a jet venturi scrubber. CONSTITUTION: A method for collecting fluorosilicic acid in a phosphoric acid manufacturing process includes the following: evaporative gas containing fluoride compounds is induced to a multi-staged vortex scrubber(20), and fluorosilicic acid(H_2SiF_6) in a washing solution form by contacting the evaporative gas with water; moisture is eliminated from the gas using a demister, and the gas is emitted; the gas through the multi-staged vortex scrubber is induced to a jet venturi scrubber(30); water sprayed from the venturi tube(31) of the jet venturi scrubber is in contact with the gas to collect fluorosilicic acid in a washing solution form; moisture is eliminated from the gas through a separator(32); and the washing solutions are stored.

Description

Method and apparatus for recovering silicic acid in the phosphoric acid manufacturing process {METHOD AND APPARATUS FOR RECOVERING HEXAFLUOROSILICIC ACID FROM MANUFACTURING PROCESS OF PHOSPHORIC ACID}

The present invention relates to a method and apparatus for obtaining silicic acid (H ₂ SiF ₆ ), in particular a method and apparatus for recovering silicic acid (H ₂ SiF ₆ ) in a phosphoric acid manufacturing process known as wet process (wet process). It is about.

The mineral resources of fluorine chemical industry are three kinds of minerals such as natural Cryolite, Fluorapatite, and Fluorspar, and these mineral resources are mainly Mexico, South Africa, USA, Russia and UK. It is ubiquitous in western Europe such as Spain and Spain, and is currently searching for new fluoride resources due to depletion of fluoride mineral resources and monopoly of some countries.

Phosphorite (CaF ₂ -3Ca ₃ (PO ₄ ) ₃ ) contains about 3.5% of fluorine (F), which is converted to a large amount of hydrogen fluoride (HF) during the phosphate production process by the wet process.

This hydrogen fluoride reacts with silica (SiO ₂ ), which is contained as an impurity in phosphate ores, and is converted into volatile silicon fluoride (SiF ₄ ). If it is released as it is, it may cause serious pollution. Should be.

However, during the phosphate manufacturing process by the wet method, since fluorine compounds from phosphate ore are present or discharged in the whole process, it is difficult to select a material of a device for the recovery of fluorine-containing waste gas due to corrosion problems, which causes a rise in investment costs. Therefore, in order to increase economics, it is necessary to improve the recovery efficiency.

The present invention has been made to solve the problems as described above, one embodiment of the present invention, the recovery efficiency is high in the recovery of silicic acid in the phosphoric acid manufacturing process, the difficulty of material selection of the device due to corrosion The present invention relates to a method and apparatus for recovering silicic acid in a phosphoric acid manufacturing process that can be solved.

According to one preferred embodiment of the present invention, in the method of recovering silicic acid in the phosphoric acid manufacturing process using phosphate ore, the gas evaporated while containing the fluorine compound is introduced into a multistage vortex type scrubber, and water is added to the gas. Recovering silicic acid (H ₂ SiF ₆ ) in the form of a cleaning liquid by spraying and contacting the gas, and passing the multistage vortex type scrubber through which the gas is released after the moisture is removed by the demister; The gas passing through the multistage vortex type scrubber is led to a jet venturi scrubber, and the water discharged from the venturi tube of the jet venturi scrubber is brought into contact with the gas to recover silicic acid (H ₂ SiF ₆ ) in the form of a cleaning liquid. Passing through the jet venturi scrubber is released after the water is removed while passing through the separator; And a silicic acid recovery step of storing the cleaning liquid of the multistage vortex type scrubber and the cleaning liquid of the jet venturi scrubber; and, by offsetting the pressure difference between the multistage vortex type scrubber and the jet venturi scrubber, the multistage vortex type scrubber without pressure drop throughout the process. Provided is a method for recovering silicic acid in a phosphoric acid manufacturing process, wherein a furnace gas is introduced.

In addition, the gas evaporated from the vacuum cooler containing the fluorine compound is introduced, and water is injected into the gas to recover silicic acid (H ₂ SiF ₆ ) in the form of a cleaning liquid, and moisture is removed by a demister. Multistage vortex scrubbers for releasing gas; Installed on one side of the multistage vortex type scrubber, the gas passing through the multistage vortex type scrubber flows in through the connecting pipe, and the gas is brought into contact with the water sprayed from the venturi tube to form silicic acid (H ₂ SiF ₆ ). A jet venturi scrubber which recovers the gas and discharges the gas from which the water is removed by the separator to the condenser; And a storage tank for storing the cleaning liquid of the multistage vortex type scrubber and the cleaning liquid of the jet venturi scrubber, wherein the gas flows into the multistage vortex type scrubber by the pressure difference cancellation between the multistage vortex type scrubber and the jet venturi scrubber. An apparatus for recovering silicic acid in a phosphoric acid manufacturing process is provided.

According to the method and apparatus for recovering silicic acid in the phosphoric acid manufacturing process according to an embodiment of the present invention, air and water pollution can be prevented by recovering silicic acid from the fluorine-containing waste gas generated in the phosphoric acid manufacturing process. There is an import substitution effect by obtaining hydrofluoric acid.

In addition, by continuously passing the waste gas through the multistage vortex type scrubber and the jet venturi scrubber, the recovery efficiency of silicic acid is increased, and at this time, due to the interaction of the multistage vortex type scrubber and the jet venturi scrubber (pressure offset offset), By eliminating the need for additional power equipment, the difficulty of selecting blower materials for corrosive gases can be solved.

1 is a schematic view showing a phosphate manufacturing process using a phosphate ore according to the conventional wet method.
Figure 2 is a process diagram showing a silicic acid recovery method in the phosphoric acid manufacturing process according to an embodiment of the present invention.
Figure 3 is a schematic diagram of a multistage vortex type scrubber constituting a silicic acid recovery device in the phosphoric acid production process according to an embodiment of the present invention.
4 is a schematic diagram of a jet venturi scrubber constituting a silicic acid recovery apparatus in the phosphoric acid production process according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the method and apparatus for recovering silicic acid in the phosphoric acid manufacturing process according to an embodiment of the present invention. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description.

In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout the specification.

In addition, the following embodiments are not intended to limit the scope of the present invention, but merely as exemplifications of the constituent elements set forth in the claims of the present invention, and are included in technical ideas throughout the specification of the present invention, Embodiments that include components replaceable as equivalents in the elements may be included within the scope of the present invention.

Example

Figure 1 is a schematic diagram showing a phosphate manufacturing process using a phosphate ore according to the conventional wet method.

In the wet process, one of the processes for producing phosphate using phosphate ore, the process starts from pulverizing ore for smooth decomposition of phosphate by sulfuric acid (H ₂ SO ₄ ).

Subsequently, the phosphate is decomposed into sulfuric acid to become hemi-slurry, a mixture of phosphoric acid and hemihydrate gypsum, and the hemi slurry is phosphoric acid (44% to 46% P ₂ O ₅ ) and hemihydrate gypsum in a belt filter. The half gypsum is washed with low concentration phosphoric acid which is circulated again, converted to dihydrate gypsum, filtered and washed and sent to the final gypsum treatment plant.

In this process, phosphoric acid (44% ~ 46% P ₂ O ₅ ) produced from hemislurry is used as raw material for the manufacture of phosphate fertilizer or compound fertilizer.

The reaction at this time is an exothermic reaction, and as the reaction proceeds, the process temperature rises, causing a decrease in yield. In order to prevent this, a vacuum cooler 1 is installed to prevent this from occurring inside the digester 2. A portion of the slurry is cooled / circulated.

At this time, the waste gas containing the fluorine compound (HF, SiF ₄ ) is generated from the vacuum cooler (1), conventionally it was introduced into the condenser (3), after the neutralization process, disposed of.

The invention fluoride (HF, SiF ₄₎ with water (H ₂ O) as if the rules hydrofluoric acid (H ₂ SiF ₆₎ in view of the fact that to be obtained, the rules hydrofluoric acid (H ₂ conventionally disposed of waste gas was absorbed SiF ₆ ) to recover a method and apparatus therefor, the silicic acid recovery device (hereinafter referred to as 'silic acid recovery device') 10 in the phosphoric acid production process according to an embodiment of the present invention, the wet method It is installed in the process line between the vacuum cooler (1) and the condenser (3) of the phosphoric acid production process.

2 is a process chart showing a silicic acid recovery method in the phosphate production process according to an embodiment of the present invention, Figure 3 is a multi-stage constituting the silicic acid recovery apparatus in the phosphate production process according to an embodiment of the present invention 4 is a schematic diagram of a vortex type scrubber, and FIG. 4 is a schematic diagram of a jet venturi scrubber constituting a silicic acid recovery apparatus in a phosphoric acid production process according to an embodiment of the present invention.

As shown in FIG. 2, the silicic acid recovery apparatus 10 according to the exemplary embodiment of the present invention may include a multistage vortex type scrubber 20 into which a gas evaporated from the vacuum cooler 1 while being evaporated is introduced. ), A jet venturi scrubber 30 installed at one side of the multistage vortex type scrubber 20, and the gas having passed through the multistage vortex type scrubber 20, and the gas is a multistage vortex type scrubber 20 and a jet venturi scrubber ( It includes a storage tank 40 for storing the silicic acid generated in the process of passing through 30, wherein the gas is in contact with water in the process of passing through the multistage vortex type scrubber 20 and the jet venturi scrubber 30, the silicic acid Is stored in the storage tank 40 in the form of a cleaning liquid.

As shown in FIG. 3, the multistage vortex type scrubber 20 according to the exemplary embodiment of the present invention includes a primary scrubber 21 and a primary water tank 21 and a secondary water tank 22 which are divided into left and right sides, respectively. It is composed of chasrubbers.

At this time, the upper end of the primary water tank 21 is in communication with the vacuum cooler 1 by a connecting pipe, the lower end of the primary water tank 21 so that the primary water tank nozzle 211 to be immersed in the water of the primary water tank 21. ) Is installed, one end of the primary tank 21 is connected to the water tank connecting pipe 212 so that the end is immersed in the water of the secondary tank 22, the gas passing through the primary tank 21 is again 2 After passing through the water tank 22 is moved to the jet venturi scrubber 30 through the discharge pipe formed on the top of the second water tank 22.

In addition, at least one injection nozzle 213 is installed at an upper portion of the primary water tank 21 to recover the silicic acid in the form of a cleaning liquid by spraying water on the gas introduced therein, whereby the primary water tank 21 is used. The cleaning liquid stored in the lower end of the) is temporarily stored in the first service tank 50, recycled to the injection nozzle 213 by a pump, and re-injected into the incoming gas, thereby concentrating the silicic acid.

The gas introduced into the primary water tank 21 and contacted with the water sprayed from the injection nozzle 213 has a cleaning liquid in the process of passing through the primary water tank nozzle 211 immersed in the water of the primary water tank 21. In contact with again, the end is in contact with the cleaning liquid in the process of flowing into the secondary tank 22 through the tank connection pipe 212 immersed in the water of the secondary tank 22, thereby improving the recovery efficiency of silicic acid The cleaning solution of the secondary water tank 22 may be temporarily stored in the first service tank 50 and recycled by a pump to concentrate.

The upper part of the secondary tank 22 is spaced apart from each other, the multi-stage partition wall 221 is installed in a zigzag manner, the gas introduced into the secondary tank 22 from the primary tank 21 through the tank connection pipe 212 Ascends to the top through the partition 221, the water is removed in the process of passing through the demister (222) installed on the top of the partition 221 is discharged through the discharge pipe.

One side of the multi-stage vortex type scrubber 20 is provided with a jet venturi scrubber 30, the jet venturi scrubber 30 is installed on one side of the venturi tube 31 and the venturi tube 31 is installed vertically, the lower end It comprises a separator 32 in communication with the lower end of the venturi tube (31).

At this time, the upper end of the venturi tube 31 is in communication with the discharge pipe installed in the upper end of the second tank 22 of the multistage vortex type scrubber 20, the gas passed through the multistage vortex type scrubber 20 flows into the venturi tube 31. do.

The gas flowing into the venturi tube 31 is smoothly induced by the pressure of the water injected from the upper end of the venturi tube 31 to contact with the water and moves rapidly to the bottom along the venturi tube 31. It is recovered in the form of this washing liquid.

At this time, since the pressure (for example, +200 mmAq) generated by the water injection of the venturi tube 31 and the pressure loss (for example, -250 mmAq) of the multistage vortex type scrubber 20 are offset, Due to the action, it is not necessary to install a separate blower (blower) in the multistage vortex type scrubber 20, thus solving the difficulty of selecting a blower material for the corrosive gas.

Meanwhile, the cleaning liquid stored at the lower end of the venturi tube 31 is temporarily stored in the second service tank 60, recycled to the upper end of the venturi tube 31 by a pump, and re-injected into the incoming gas. The concentrated and water-containing gas is introduced into the lower end of the separator 32 and then discharged after the water is removed in the ascending process to flow into the condenser 3.

The concentrated silicic acid is stored in the first service tank 50 in the form of a cleaning liquid, and the silicic acid having a lower concentration than the silicic acid in the first service tank is stored in the form of a cleaning liquid in the second service tank 60. In addition, the cleaning liquid stored in the first service tank 50 and the second service tank 60 is transferred to the storage tank 40 by a pump, and finally recovers the silicic acid, which is recovered from the tap water fluorination business. It can be used as a fluorine additive or as a raw material for the production of metal surface treatment agents or polysilicon.

Therefore, the silicic acid recovery method in the phosphoric acid manufacturing process according to an embodiment of the present invention will be described step by step.

Multistage Vortex Scrubber  Passing Steps:

In the phosphoric acid manufacturing process using phosphate ore, the gas evaporated from the vacuum cooler 1 in the state containing fluorine compound is led to a multistage vortex type scrubber 20, and water is injected into the gas to contact the gas in the form of a cleaning liquid. Recovers the silicic acid, the gas is released after the moisture is removed by the demister 222.

At this time, the gas is contacted with water in the process of passing through the injection nozzle 213, the primary tank nozzle 211 and the water tank connecting pipe 212, the silicic acid is recovered in the form of the cleaning liquid, the cleaning liquid is the first service tank ( It is concentrated by repeating the process of being temporarily stored in 50), recycled by a pump and re-injected into gas again.

Z Venturi Scrubber  Passing Steps:

Gas passing through the multistage vortex type scrubber 20 flows into the jet venturi scrubber 30 and comes into contact with water sprayed from the venturi tube 31 to recover silicic acid in the form of a cleaning liquid, and the gas is separated from the separator 32. After passing through the water, the water is removed and discharged to the condenser (3). The cleaning solution is temporarily stored in the second service tank (60), recycled by a pump, and then injected into the gas. .

At this time, the water injection pressure generated in the jet venturi scrubber 30 cancels the pressure loss of the multistage vortex type scrubber 20, so that a separate blower does not need to be installed in the multistage vortex type scrubber 20.

Silicic acid  Recovery Steps:

Strong concentrations of silicic acid produced in the multistage vortex type scrubber 20 and stored in the first service tank 50 and relatively weak concentrations generated in the jet venturi scrubber 30 and stored in the second service tank 60. Of silicic acid is collected in the storage tank 40, the silicic acid is finally recovered.

10: silicic acid recovery device
20: Multistage Vortex Scrubber
21: 1st tank
211: 1st tank nozzle
212: water tank connector
213: injection nozzle
22: secondary plate
221: bulkhead
222: Demister
30: Jet Venturi Scrubber
31: Venturi tube
32: Separator
40: storage tank
50: first service tank
60: second service tank

Claims (7)

In the method of recovering silicic acid in the phosphoric acid manufacturing process using phosphate ore,
The gas evaporated while containing the fluorine compound is led to a multistage vortex type scrubber, and water is contacted by spraying water on the gas to recover silicic acid (H ₂ SiF ₆ ) in the form of a cleaning liquid. Passing the multistage vortex type scrubber discharged after the water is removed by;
The gas passing through the multistage vortex type scrubber is led to a jet venturi scrubber, and the water jetted from the venturi tube of the jet venturi scrubber is brought into contact with the gas to recover silicic acid (H ₂ SiF ₆ ) in the form of a cleaning liquid. The gas passes through the jet venturi scrubber discharged after the water is removed while passing through the separator; And
And a silicic acid recovery step of storing the cleaning solution of the multistage vortex type scrubber and the cleaning solution of the jet venturi scrubber.
A method for recovering silicic acid in a phosphate production process, wherein gas is introduced into the multistage vortex type scrubber without pressure drop throughout the process by the pressure difference cancellation between the multistage vortex type scrubber and the jet venturi scrubber.
The method according to claim 1,
In the multistage vortex type scrubber passing step and the jet venturi scrubber passing step, the cleaning liquid is recycled and concentrated by re-injection into a gas, the silicic acid recovery method in the phosphate production process.
In the silicic acid recovery device provided between the vacuum cooler and the condenser of the phosphoric acid manufacturing process using phosphate ore,
The gas evaporated from the vacuum cooler containing the fluorine compound is introduced, and water is injected into the gas to recover silicic acid (H ₂ SiF ₆ ) in the form of a washing liquid, and water is removed by a demister. Multistage vortex scrubbers for releasing gas;
Installed on one side of the multistage vortex type scrubber, the gas passing through the multistage vortex type scrubber flows in through the connecting tube, and the gas is contacted with water sprayed from the venturi tube to form silicic acid (H ₂ SiF) in the form of a cleaning liquid. ₆ ) a jet venturi scrubber for recovering and discharging the gas from which moisture has been removed by the separator to the condenser; And
And a storage tank for storing the cleaning liquid of the multistage vortex type scrubber and the cleaning liquid of the jet venturi scrubber.
An apparatus for recovering silicic acid in a phosphate production process, wherein gas is introduced into the multistage vortex type scrubber by the pressure difference cancellation between the multistage vortex type scrubber and the jet venturi scrubber.
The method according to claim 3,
The multistage vortex type scrubber and the cleaning liquid of the jet venturi scrubber are each recycled by a pump, concentrated by re-injection into gas, and then stored in the storage tank.
The method according to claim 3, wherein the multistage vortex type scrubber,
A primary tank and a secondary tank are partitioned from side to side, and a primary tank nozzle is installed at a lower end of the primary tank communicating with the vacuum cooler so as to be immersed in the water of the primary tank, and one end of the primary tank is disposed at an end thereof. A water tank connection pipe is connected to be immersed in the water of the secondary tank, and the gas passing through the primary tank passes through the secondary tank again and is discharged to the jet venturi scrubber through a discharge pipe formed at the top of the secondary tank. An apparatus for recovering silicic acid in the phosphoric acid manufacturing process, characterized in that
The method according to claim 5,
At least one injection nozzle is installed at an upper portion of the primary tank, and a partition wall is installed on the upper portion of the secondary tank in a zigzag manner, and a demister is installed at the upper portion of the partition wall. Silicic acid recovery device.
The method according to claim 3, wherein the jet venturi scrubber,
Venturi tube vertically installed so as to communicate with the multi-stage vortex type scrubber, and the separator is installed on one side of the venturi tube, the venturi tube and the separator in the phosphate manufacturing process, characterized in that the lower end is in communication with each other Silic acid recovery device.

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