An apparatus for recovering boric acid from a sodium sulfate solution

Abstract

The utility model discloses a device for recovering boric acid from sodium sulfate solution, which comprises a cooling kettle, a double-cone cyclone separator, a centrifuge, a boric acid mother liquor tank and a sodium sulfate mother liquor tank. The cooling kettle has a cooling jacket on its outer side. The cooling kettle is connected with the double-cone cyclone separator. The double-cone cyclone separator is connected with the centrifuge, the boric acid mother liquor tank and the sodium sulfate mother liquor tank respectively. The centrifuge is connected with the boric acid mother liquor tank. The boric acid mother liquor tank is connected with the sodium sulfate mother liquor tank. Through the step-by-step (cooling) crystallization method, the great difference in solubility with temperature change is utilized to remove sodium sulfate at high temperature and precipitate boric acid at low temperature, so that boric acid is recovered from sodium sulfate solution. The operation is relatively simple, cost-effective and easy to industrialize.

Description

Technical Field

[0001] This utility model relates to the field of boric acid recovery technology, specifically to a device for recovering boric acid from sodium sulfate solution. Background Technology

[0002] Electrolytic nickel deposition is a process that uses electrolytic deposition technology to directly extract high-purity metallic nickel from a pure aqueous solution containing nickel ions. It is a core step in modern hydrometallurgical processing of resources such as laterite nickel ore. The resulting nickel cathode plate is one of the important basic nickel products and is widely used in industries such as stainless steel, alloys, electroplating, and batteries.

[0003] The solution after nickel electrolysis mainly contains sodium sulfate and a small amount of boric acid. However, the higher the concentration of sodium sulfate, the more difficult the separation becomes. Therefore, this invention proposes a device for recovering boric acid from sodium sulfate solution that can solve the above problems. Utility Model Content

[0004] The purpose of this invention is to provide an apparatus for recovering boric acid from sodium sulfate solution, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an apparatus for recovering boric acid from sodium sulfate solution, comprising a cooling kettle, a double-cone cyclone separator, a centrifuge, a boric acid mother liquor tank and a sodium sulfate mother liquor tank, wherein the cooling kettle has a cooling jacket on its outer side and the cooling kettle is connected to the double-cone cyclone separator;

[0006] The double-cone cyclone separator is connected to a centrifuge, a boric acid mother liquor tank, and a sodium sulfate mother liquor tank, respectively. The centrifuge is connected to the boric acid mother liquor tank, and the boric acid mother liquor tank is connected to the sodium sulfate mother liquor tank.

[0007] Preferably, the cooling jacket is connected to inlet and outlet valves for cooling circulating water and inlet and outlet valves for refrigerant.

[0008] Preferably, the centrifuge is connected to a pipe, the pipe extends to a support, and a ton bag for collecting crystals is placed on the support.

[0009] Preferably, the sodium sulfate mother liquor tank is connected to the evaporation and concentration system via a pump.

[0010] Compared with the prior art, the beneficial effects of this utility model are:

[0011] By using a stepwise (cooling) crystallization method, taking advantage of the significant difference in solubility of the two substances with temperature, sodium sulfate is removed by high-temperature concentration and boric acid is precipitated by low-temperature cooling. This method allows for the recovery of boric acid from sodium sulfate solution, which is relatively simple, cost-effective, and easy to industrialize. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0013] Figure 2 This is a schematic diagram showing the boric acid crystals being packaged in ton bags at the centrifuge of this utility model.

[0014] Figure 3 Schematic diagram of the cooling vessel structure of this utility model;

[0015] In the diagram: 10. Cooling vessel; 11. Cooling jacket; 20. Double cone cyclone separator; 30. Centrifuge; 31. Support frame; 32. Ton bag; 40. Boric acid mother liquor tank; 50. Sodium sulfate mother liquor tank; 60. Pump body. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Please see Figure 1-3

[0018] The solution properties of the eluent are: sodium sulfate content 25%, boric acid content 3%, and water content 72%. The recovery of boric acid (H3BO3) from a sodium sulfate (Na2SO4) solution is a typical separation problem, mainly utilizing the physicochemical properties of both (especially the difference in solubility with temperature).

[0019] The solubility of boric acid (H3BO3) increases significantly with increasing temperature. Its solubility in cold water (20°C) is about 5%, while its solubility in boiling water (100°C) can reach about 27-30%. It easily crystallizes upon cooling, and the crystals have high purity.

[0020] Sodium sulfate (Na2SO4): The solubility curve has an inflection point (about 32.4°C). Below this temperature, the solubility of sodium sulfate decahydrate (Na2SO4·10H2O) increases with increasing temperature; above this temperature, the solubility of anhydrous sodium sulfate (Na2SO4) decreases with increasing temperature. It is easy to saturate and precipitate when concentrated at higher temperatures (>32.4°C).

[0021] Example 1

[0022] An apparatus is provided for recovering boric acid from a sodium sulfate solution:

[0023] The cooling vessel 10 has a cooling jacket 11 on its outside. The cooling jacket 11 is connected to the inlet and outlet valves of cooling circulating water and the inlet and outlet valves of refrigerant. Controlling the inlet and outlet valves of cooling circulating water can deliver cooling circulating water into the cooling jacket 11 to cool and lower the mother liquor. Controlling the inlet and outlet valves of refrigerant can deliver refrigerant (ethylene glycol solution) to cool and lower the mother liquor.

[0024] The cooling vessel 10 is connected to the double cone cyclone separator 20, which performs gravity separation on the cooled mother liquor.

[0025] The double-cone cyclone separator 20 is connected to the centrifuge 30, the boric acid mother liquor tank 40 and the sodium sulfate mother liquor tank 50 respectively. The centrifuge 30 is connected to the boric acid mother liquor tank 40 and the boric acid mother liquor tank 40 is connected to the sodium sulfate mother liquor tank 50. The sodium sulfate mother liquor tank 50 is connected to the evaporation and concentration system through the pump body 60.

[0026] Centrifuge 30 is connected to a pipe, which extends to a support 31. A ton bag 32 for collecting crystals is placed on the support 31. The centrifuge 30 separates boric acid crystal products, which are then packaged in the ton bag 32.

[0027] Example 2

[0028] An acid precipitation process for recovering boric acid from sodium sulfate solution is provided:

[0029] S1, sodium sulfate and boric acid solution enter cooling vessel 10;

[0030] S2. Add dilute sulfuric acid to cooling tank 10 to adjust the mother liquor to acidity (pH≈2~4). Open the inlet and outlet valves of the cooling circulating water. The cooling circulating water cools the mother liquor through the cooling jacket 11. After about 2 hours of cooling, when the temperature inside the cooling tank 10 reaches 50~60℃, close the inlet and outlet valves of the circulating cooling water. At this time, due to the change in temperature and acidity, boric acid precipitates in the solution, but sodium sulfate does not precipitate.

[0031] S3. Open the discharge valve of the cooling kettle 10. The crystallization mother liquor enters the double cone cyclone separator 20. The mother liquor undergoes gravity separation in the double cone cyclone separator 20. The mother liquor containing boric acid crystals enters the centrifuge 30 from the bottom of the double cone separator for centrifugal separation to obtain boric acid crystal products, which are then packaged in ton bags 32.

[0032] S4. The separated mother liquor enters the boric acid mother liquor tank 40, and the dilute alkali is added to the mother liquor tank to adjust the pH to ~8. The mother liquor in the boric acid mother liquor tank 40 overflows into the sodium sulfate mother liquor tank 50 and is pumped into the evaporation system by the pump body 60 for re-evaporation and concentration.

[0033] Example 3

[0034] A freezing process for recovering boric acid from sodium sulfate solution is provided:

[0035] S1, a 25% sodium sulfate and a 3% boric acid solution are introduced into the cooling vessel 10;

[0036] S2. Open the inlet and outlet valves of the refrigerant and the inlet and outlet valves of the cooling circulating water. The low-temperature refrigerant (ethylene glycol solution) enters the cooling tank 10 to exchange heat with the mother liquor. After about 2 hours, when the temperature cools down to about 0°C, sodium sulfate and boric acid crystals precipitate.

[0037] S3. Open the discharge valve of the cooling kettle 10. The crystallization mother liquor enters the double cone cyclone separator 20. The solids of sodium sulfate and boric acid are separated by gravity in the double cone cyclone separator 20. The sodium sulfate mother liquor flows into the sodium sulfate mother liquor tank 50 in the lower layer. The mother liquor with boric acid crystals flows from the top of the double cone separator to the centrifuge 30 for centrifugal separation to obtain boric acid crystal products. The products are packaged in ton bags 32. The sodium sulfate crystals at the bottom of the double cone separator directly enter the sodium sulfate mother liquor tank 50V051.

[0038] S4. After separation, the mother liquor enters the boric acid mother liquor tank 40. Dilute alkali is pumped into the mother liquor tank to adjust the pH to ~8. The mother liquor in the boric acid mother liquor tank 40 overflows into the sodium sulfate mother liquor tank 50 and is pumped into the evaporation system by the pump body 60 for re-evaporation and concentration.

[0039] By using a stepwise (cooling) crystallization method, taking advantage of the significant difference in solubility of the two substances with temperature, sodium sulfate is removed by high-temperature concentration and boric acid is precipitated by low-temperature cooling. This method allows for the recovery of boric acid from sodium sulfate solution, which is relatively simple, cost-effective, and easy to industrialize.

[0040] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An apparatus for recovering boric acid from a sodium sulfate solution, characterized by, It includes a cooling vessel (10), a double cone cyclone separator (20), a centrifuge (30), a boric acid mother liquor tank (40), and a sodium sulfate mother liquor tank (50). The cooling vessel (10) has a cooling jacket (11) on its outside and is connected to the double cone cyclone separator (20). The double-cone cyclone separator (20) is connected to a centrifuge (30), a boric acid mother liquor tank (40), and a sodium sulfate mother liquor tank (50), respectively. The centrifuge (30) is connected to the boric acid mother liquor tank (40), and the boric acid mother liquor tank (40) is connected to the sodium sulfate mother liquor tank (50).

2. The apparatus for recovering boric acid from sodium sulfate solution according to claim 1, characterized in that, The cooling jacket (11) is connected to the inlet and outlet valves for cooling circulating water and the inlet and outlet valves for refrigerant.

3. The apparatus for recovering boric acid from sodium sulfate solution according to claim 1, characterized in that, The centrifuge (30) is connected to a pipe, which extends to a support (31) on which a ton bag (32) for collecting crystals is placed.

4. The apparatus for recovering boric acid from sodium sulfate solution according to claim 1, characterized in that, The sodium sulfate mother liquor tank (50) is connected to the evaporation and concentration system via a pump (60).

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