System for separating and purifying ammonium sulfate in electrolytic manganese residue

Abstract

The utility model discloses a system of ammonium sulfate separation and purification in electrolytic manganese residue, including mixed gas pipeline, heat exchanger a, heat exchanger b, heat exchanger c and multistage refrigerating unit, heat exchanger a, heat exchanger b and heat exchanger c are connected in proper order in series, and multistage refrigerating unit sends into cold medium heat exchange to heat exchanger a, heat exchanger b and heat exchanger c respectively, and mixed gas pipeline is linked with heat exchanger a, and the output of heat exchanger a, heat exchanger b and heat exchanger c is provided with gas -liquid separation tank a, gas -liquid separation tank b and gas -liquid separation tank c respectively. The system of ammonium sulfate separation and purification in electrolytic manganese residue, utilize the different characteristics of the boiling point of gaseous sulfuric acid, sulfur dioxide, ammonia and nitrogen in mixed gas, condense it respectively and gradually recycle, and component utilization is used in preparation sulfuric acid ammonium and nitrogen recovery, and sulfur dioxide is separated out, avoids because sulfur dioxide influence and reduces the recovery efficiency of ammonium sulfate.

Description

Technical Field

[0001] This utility model relates to the technical field of equipment and method for recovering ammonium sulfate from electrolytic manganese slag, specifically a system for separating and purifying ammonium sulfate from electrolytic manganese slag. Background Technology

[0002] Electrolytic manganese ammonium sulfate residue contains approximately 45% ammonium sulfate. Because this type of double salt is a mixture of sulfates such as ammonium sulfate, manganese sulfate, magnesium sulfate, and calcium sulfate, the ammonium sulfate cannot be directly utilized, leading to the stockpiling of this mixture. According to Chinese Patent 2025103245795, a system and method for producing ammonium sulfite from electrolytic manganese ammonium sulfate double salt is proposed. This method utilizes the decomposition reaction of ammonium sulfate at a certain temperature to generate ammonia and ammonium bisulfate. However, the electrolytic manganese ammonium sulfate residue contains ammonium sulfate and other impurities. By controlling the low-temperature calcination conditions, ammonium sulfate is preferentially decomposed and volatilized in gaseous form. Then, a specific device collects and converts the volatilized ammonia and ammonium bisulfate, regenerating ammonium sulfate, thereby achieving ammonium sulfate recovery.

[0003] During low-temperature calcination, excessively high temperatures may cause ammonium sulfate to decompose excessively, generating gases such as nitrogen and sulfur dioxide that are difficult to recover, thus reducing the recovery efficiency of ammonium sulfate. Nitrogen is a relatively stable chemical gas, poorly soluble in water, and does not react chemically with ammonium sulfate or water. However, sulfur dioxide is readily soluble in water and reacts with water to form sulfurous acid, which increases the concentration of hydrogen ions in the solution and enhances the acidity of the solution. Ammonium sulfate is a salt of a strong acid and a weak base, and its hydrolysis produces an acidic solution. The change in solution acidity inhibits the hydrolysis of ammonium ions in ammonium sulfate, causing a change in the solubility of ammonium sulfate in water, which in turn affects the absorption effect of water on ammonium sulfate, thereby reducing the recovery efficiency of ammonium sulfate. Therefore, this application is made. Utility Model Content

[0004] The purpose of this invention is to provide a system for separating and purifying ammonium sulfate from electrolytic manganese slag, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A system for separating and purifying ammonium sulfate from electrolytic manganese slag includes a mixed gas pipeline, heat exchangers a, b, and c, and a multi-stage refrigeration unit. Heat exchangers a, b, and c are connected in series. The multi-stage refrigeration unit supplies cold media to heat exchangers a, b, and c respectively. The mixed gas pipeline is connected to heat exchanger a. Gas-liquid separators a, b, and c are respectively installed at the output ends of heat exchangers a, b, and c to separate sulfuric acid, sulfur dioxide, and ammonia. Liquid ammonia output from gas-liquid separator c is connected to a heated reaction vessel b via a liquid ammonia pipeline. Sulfuric acid output from gas-liquid separator a is connected to the reaction vessel via a sulfuric acid pipeline. The heated reaction vessel b is connected to the reaction vessel via an ammonia pipeline.

[0007] As a further embodiment of this utility model: the heat exchange temperature of heat exchanger a is 50-0℃, the heat exchange temperature of heat exchanger b is -15--35℃, and the heat exchange temperature of heat exchanger c is -40--50℃.

[0008] As a further embodiment of this utility model: the liquid phase output end of the gas-liquid separator b is connected to the heating reactor a via a sulfur dioxide pipeline, the heating reactor a is connected to the absorption tower via a separation pipeline, and the top of the absorption tower is connected to the heating reactor b via an ammonia recovery pipeline.

[0009] As a further improvement of this utility model, the absorption tower is equipped with an additive pipeline and an absorbent liquid pipeline.

[0010] As a further embodiment of this utility model: heat exchanger a and heat exchanger b are connected by conveyor line a, gas-liquid separator a is installed on conveyor line a, the liquid phase output end of gas-liquid separator a is connected to sulfuric acid pipeline, the gas phase output end of gas-liquid separator a is connected to heat exchanger b, heat exchanger b and heat exchanger c are connected by conveyor line b, gas-liquid separator b is installed on conveyor line b, the gas phase output end of gas-liquid separator b is connected to heat exchanger c, the output end of heat exchanger c is connected to gas-liquid separator c through conveyor line c, and the gas phase output end of gas-liquid separator c is connected to tail gas pipeline.

[0011] Compared with the prior art, the beneficial effects of this utility model are:

[0012] 1. The system for separating and purifying ammonium sulfate in electrolytic manganese slag utilizes the different boiling points of gaseous sulfuric acid, sulfur dioxide, ammonia and nitrogen in the mixed gas to condense and recover them step by step, and the components are used to prepare ammonium sulfate and recover nitrogen. Sulfur dioxide is separated out to avoid the reduction of ammonium sulfate recovery efficiency due to sulfur dioxide.

[0013] 2. The system for separating and purifying ammonium sulfate in electrolytic manganese slag further recovers ammonia from sulfur dioxide condensate through an alkaline absorbent. Ammonia reacts with sulfuric acid in a certain proportion to generate ammonium sulfate. The ammonium sulfate recovered in this way has a high concentration and completely separates sulfur dioxide without affecting the recovery of ammonium sulfate, thereby improving the recovery rate of ammonium sulfate, reducing water consumption, and decreasing industrial water use. Attached Figure Description

[0014] Figure 1 This is a system diagram for the separation and purification of ammonium sulfate from electrolytic manganese slag.

[0015] In the diagram: 1. Mixed gas pipeline; 2. Heat exchanger a; 3. Heat exchanger b; 4. Heat exchanger c; 5. Multi-stage refrigeration unit; 6. Conveyor line a; 7. Conveyor line b; 8. Conveyor line c; 9. Tail gas pipeline; 10. Gas-liquid separator a; 11. Gas-liquid separator b; 12. Gas-liquid separator c; 13. Sulfuric acid pipeline; 14. Sulfur dioxide pipeline; 15. Liquid ammonia pipeline; 16. Ammonia recovery pipeline; 17. Heated reaction vessel b; 18. Absorption tower; 19. Separation pipeline; 20. Heated reaction vessel a; 21. Ammonia pipeline; 22. Reaction vessel; 23. Ammonium sulfate pipeline; 24. Absorbent liquid pipeline; 25. Additive pipeline. Detailed Implementation

[0016] Please see Figure 1 In this embodiment of the invention, a system for separating and purifying ammonium sulfate from electrolytic manganese slag includes a mixed gas pipeline 1, heat exchangers a2, b3, and c4, and a multi-stage refrigeration unit 5. Heat exchangers a2, b3, and c4 are connected in series. The multi-stage refrigeration unit 5 supplies cold media to heat exchangers a2, b3, and c4 respectively. The mixed gas pipeline 1 is connected to heat exchanger a2. Gas-liquid separators a10, b11, and c12 are respectively installed at the output ends of heat exchangers a2, b3, and c4 to separate sulfuric acid, sulfur dioxide, and... Ammonia gas is produced by liquid ammonia output from gas-liquid separator C12, which is connected to heated reactor B17 via liquid ammonia pipeline 15. Sulfuric acid output from gas-liquid separator A10 is connected to reactor 22 via sulfuric acid pipeline 13. Heated reactor B17 is connected to reactor 22 via ammonia pipeline 21. The multi-stage refrigeration unit 5 is existing technology, which can precisely control the refrigeration temperature by adjusting the refrigeration capacity output of different stages, meeting the temperature accuracy requirements of various processes and environments. Through multi-stage compression, the refrigerant is compressed and expanded at different pressure levels, which can be closer to the ideal refrigeration cycle, improve refrigeration efficiency, and reduce energy consumption.

[0017] In a preferred embodiment, the heat exchange temperature of heat exchanger a2 is 50-0℃, the heat exchange temperature of heat exchanger b3 is -15-35℃, and the heat exchange temperature of heat exchanger c4 is -40-50℃. Sulfuric acid has a high boiling point, so the temperature for condensing and recovering gaseous sulfuric acid only needs to be controlled between 50-100℃. The heat exchange temperature of heat exchanger a2 at 50-0℃ effectively allows for the complete condensation and recovery of gaseous sulfuric acid into a liquid state. Sulfur dioxide has a boiling point of -10℃, so the complete condensation of sulfur dioxide requires maintaining the heat exchange temperature of heat exchanger b3 at -15-35℃. Ammonia has a relatively high boiling point of -33.5℃, so the complete condensation of ammonia requires maintaining the heat exchange temperature of heat exchanger c4 at -40-50℃. Nitrogen has a very low boiling point. -195.8℃, nitrogen can be used in other stages of manganese electrolysis, such as bag filters. During the processing of metallic manganese, there is a need for the recovery of metal powder. Metal powder has high chemical activity and a large contact area with air, making it prone to oxidation. Under certain conditions, the heat generated by the oxidation reaction can accumulate and potentially cause combustion or even explosion. Therefore, replacing air with recovered nitrogen can effectively improve production safety. This application utilizes the different boiling points of gaseous sulfuric acid, sulfur dioxide, ammonia, and nitrogen in the mixed gas to condense and recover them separately. The components are then used to prepare ammonium sulfate and recover nitrogen, while separating sulfur dioxide to avoid reducing the recovery efficiency of ammonium sulfate due to sulfur dioxide.

[0018] In a preferred embodiment, the liquid phase output end of the gas-liquid separator b11 is connected to the heating reactor a20 via a sulfur dioxide pipeline 14. The heating reactor a20 is connected to the absorption tower 18 via a separation pipeline 19. The top of the absorption tower 18 is connected to the heating reactor b17 via an ammonia recovery pipeline 16. The boiling point of ammonia is -33.5℃, and the boiling point of sulfur dioxide is -10℃. The small temperature difference between the two boiling points causes a small portion of ammonia to condense during the sulfur dioxide condensation process. To recover this portion of ammonia, this application uses an absorption method to separate the liquid sulfur dioxide and ammonia by heating them into a gaseous state. The separation is achieved by utilizing the difference in solubility of sulfur dioxide and ammonia in different absorbents. Sulfur dioxide is an acidic gas and can react with alkaline solutions, while ammonia is an alkaline gas and does not react with alkaline solutions, but it can be absorbed by acidic solutions. When both are introduced into an alkaline absorbent, sulfur dioxide reacts with sodium hydroxide to form sodium sulfite or sodium bisulfite, which is then absorbed. The reaction equation is as follows:

[0019] SO2 + 2NaOH = Na2SO3 + H2O;

[0020] When sulfur dioxide is in excess;

[0021] SO₂ + 2NaOH = NaHSO₃

[0022] Ammonia does not react with sodium hydroxide solution and is discharged from the top of the absorption tower.

[0023] In a preferred embodiment, the absorption tower 18 is provided with an additive line 25 and an absorbent line 24. An alkaline absorbent, such as a sodium hydroxide solution, is added through the additive line 25, and the reaction solution is discharged as sodium sulfite and sodium bisulfite through the absorbent line 24.

[0024] In a preferred embodiment, heat exchanger a2 and heat exchanger b3 are connected by conveyor line a6. Gas-liquid separator a10 is installed on conveyor line a6. The liquid phase output end of gas-liquid separator a10 is connected to sulfuric acid pipeline 13, and the gas phase output end of gas-liquid separator a10 is connected to heat exchanger b3. Heat exchanger b3 and heat exchanger c4 are connected by conveyor line b7. Gas-liquid separator b11 is installed on conveyor line b7. The gas phase output end of gas-liquid separator b11 is connected to heat exchanger c4. The output end of heat exchanger c4 is connected to gas-liquid separator c12 via conveyor line c8. The gas phase output end of gas-liquid separator c12 is connected to tail gas pipeline 9.

[0025] A method for separating and purifying ammonium sulfate from electrolytic manganese slag, comprising the following steps:

[0026] S1: The electrolytic manganese ammonium sulfate mixture is fed into a drum high-temperature drying device and dried at 150°C;

[0027] S2: The dried mixture of S1 is crushed and sieved to 50 mesh using a crushing device;

[0028] S3: The mixture sieved through S2 is fed into an oxygen-free calcining kiln for oxygen-free calcination and decomposition.

[0029] S4: The exhaust gas generated by S3 anaerobic calcination is treated by a three-stage electrostatic precipitator connected to the rear end of the anaerobic calcination kiln.

[0030] S5: Connect the S4 three-stage electrostatic precipitator to a three-stage refrigeration and separation system. The first stage condenser separates sulfuric acid, the second stage condenser separates sulfur dioxide, and the third stage condenser separates ammonia.

[0031] S6: Restore the ammonia obtained in S5 to a gaseous state, and react sulfuric acid and ammonia in a certain proportion to produce ammonium sulfate and water;

[0032] S7; The ammonium sulfate obtained in S6 and water are sent to an evaporation system and evaporated and crystallized to obtain the ammonium sulfate product.

[0033] In a preferred embodiment, the mixture in S3 is fed into a calcining kiln and subjected to low-temperature calcination decomposition at 550-700°C for 0.2-2 hours.

[0034] In a preferred embodiment, the boiling point of sulfur dioxide in the secondary condensation separation in S5 is -10℃, and the boiling point of ammonia is -33.5℃. The boiling point temperature difference is small, and the separated sulfur dioxide contains some ammonia. It is necessary to further separate the small amount of ammonia in the sulfur dioxide.

[0035] In a preferred embodiment, ammonia gas is separated into a liquid state by a three-stage condenser. A heated reactor b17 is used to convert the liquid state into a gaseous state. The separated sulfur dioxide and ammonia mixture is sent to a heated reactor a20 to restore the gaseous state. The sulfur dioxide and ammonia mixture is then sent to an absorption tower 18. The absorption tower 18 is filled with an alkaline absorbent, such as sodium hydroxide solution. The sulfur dioxide reacts with the sodium hydroxide to form sodium sulfite or sodium bisulfite and is absorbed. The ammonia gas is then returned to the heated reactor b17.

[0036] In a preferred embodiment, the reaction vessel 22 delivers ammonium sulfate and water to the evaporation system via the ammonium sulfate pipeline 23.

[0037] The ammonium sulfate recovered in this way has a high concentration and completely separates sulfur dioxide without affecting the recovery of ammonium sulfate, thereby improving the recovery rate of ammonium sulfate, reducing water consumption, and decreasing industrial water use.

[0038] It should be noted that all the above embodiments belong to the same utility model concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0039] The embodiments described above merely illustrate the implementation of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A system for separating and purifying ammonium sulfate from electrolytic manganese slag, characterized in that, The system includes a mixing gas pipeline (1), heat exchangers a (2), b (3), c (4), and a multi-stage refrigeration unit (5). Heat exchangers a (2), b (3), and c (4) are connected in series. The multi-stage refrigeration unit (5) supplies cold media to heat exchangers a (2), b (3), and c (4) respectively. The mixing gas pipeline (1) is connected to heat exchanger a (2). The heat exchangers a (2), b (3), and c (4) are connected in series. The output end is equipped with gas-liquid separator a (10), gas-liquid separator b (11) and gas-liquid separator c (12) to separate sulfuric acid, sulfur dioxide and ammonia. The liquid ammonia output from gas-liquid separator c (12) is connected to the heating reactor b (17) through the liquid ammonia pipeline (15). The sulfuric acid output from gas-liquid separator a (10) is connected to the reactor (22) through the sulfuric acid pipeline (13). The heating reactor b (17) is connected to the reactor (22) through the ammonia pipeline (21).

2. The system for separating and purifying ammonium sulfate from electrolytic manganese slag according to claim 1, characterized in that, The heat exchange temperature of heat exchanger a (2) is 50-0℃, the heat exchange temperature of heat exchanger b (3) is -15--35℃, and the heat exchange temperature of heat exchanger c (4) is -40--50℃.

3. A system for separating and purifying ammonium sulfate from electrolytic manganese slag according to claim 1 or 2, characterized in that, The liquid phase output end of the gas-liquid separator b (11) is connected to the heating reactor a (20) via the sulfur dioxide pipeline (14). The heating reactor a (20) is connected to the absorption tower (18) via the separation pipeline (19). The top of the absorption tower (18) is connected to the heating reactor b (17) via the ammonia recovery pipeline (16).

4. The system for separating and purifying ammonium sulfate from electrolytic manganese slag according to claim 3, characterized in that, The absorption tower (18) is equipped with an additive pipeline (25) and an absorbent liquid pipeline (24).

5. The system for separating and purifying ammonium sulfate from electrolytic manganese slag according to claim 1, characterized in that, The heat exchanger a (2) and heat exchanger b (3) are connected by a conveyor line a (6). The gas-liquid separator a (10) is set on the conveyor line a (6). The liquid phase output end of the gas-liquid separator a (10) is connected to the sulfuric acid pipeline (13). The gas phase output end of the gas-liquid separator a (10) is connected to the heat exchanger b (3). The heat exchanger b (3) and heat exchanger c (4) are connected by a conveyor line b (7). The gas-liquid separator b (11) is set on the conveyor line b (7). The gas phase output end of the gas-liquid separator b (11) is connected to the heat exchanger c (4). The output end of the heat exchanger c (4) is connected to the gas-liquid separator c (12) through the conveyor line c (8). The gas phase output end of the gas-liquid separator c (12) is connected to the tail gas pipeline (9).

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