Method for all-component separation, purification and high-value utilization of waste ammonium sulfate residues

Abstract

The invention discloses a method for all-component separation, purification and high-value utilization of ammonium sulfate waste residues, which comprises the following steps: by using low-cost ammonium fluoride as a fluorine source, selectively precipitating Mg < 2 + > through one-step fluorination conversion, preparing high-purity MgF2, recovering valuable metals by combining an extraction-reverse extraction process, and preparing a manganese-magnesium ferrite material by combining sol-gel and high-temperature calcination processes. And recovering an ammonium sulfate by-product. Compared with an existing high-purity inorganic salt preparation process, high-value utilization of all-component resources in the waste residues is achieved, and the problems that waste residues are difficult to treat, cost is high and the like are solved. The method adopts a one-step fluorination conversion, extraction and reverse extraction process and a sol-gel method, and is low in cost, high in resource utilization rate, non-toxic and harmless. The prepared magnesium fluoride can be applied to the fields of optical materials and electronic ceramics; mnxMg (1-x) Fe2O4 has good magnetism and photocatalytic performance, so that organic pollutants can be degraded; the recovered ammonium sulfate can be directly used as a nitrogen fertilizer raw material, so that multi-component synergistic high-value utilization is realized.

Description

Technical Field

[0001] This invention relates to the high-value recovery of ammonium sulfate slag, specifically to a method for the complete separation, purification, and high-value utilization of ammonium sulfate slag waste. Background Technology

[0002] With the deep integration of new energy and materials industries, China's energy-intensive industries such as metallurgy, batteries, and electrolytic chemicals continue to expand, generating a large scale and diverse range of solid by-products and waste residues. Among these, ammonium sulfate slag, a by-product of manganese electrolysis, is a multi-component waste residue formed during the electrolysis of metallic manganese by reacting sulfuric acid electrolyte with ammonium salts, resulting in ammonium sulfate, magnesium ammonium sulfate, and manganese ammonium sulfate precipitates. It is rich in Mg... 2+ Mn 2+ NH4 + With SO4 2- The availability of ammonia nitrogen and metal ions has attracted widespread attention. Due to their complex composition, high water solubility, and difficulty in treatment, direct discharge or simple landfilling not only causes secondary pollution of ammonia nitrogen and metal ions, but also wastes a large amount of recyclable resources, which has become a key obstacle to the green transformation of the industry.

[0003] Traditional methods for treating ammonium sulfate slag mainly include incineration, chemical precipitation, and neutralization solidification. However, these technologies often suffer from low resource utilization, low added value of products, or serious secondary pollution, making it difficult to achieve clean and high-value transformation. CN117107050A proposes a method for synergistic mineral phase transformation of electrolytic manganese ammonium sulfate slag and manganese ore powder to remove ammonia and fix sulfur, but it suffers from drawbacks such as high energy consumption during high-temperature mineral phase transformation and high investment in process equipment. CN118811847A proposes to prepare inorganic hydrated aluminum ammonium sulfate double salt phase change material by mixing and roasting secondary aluminum ash with ammonium sulfate slag, but it suffers from drawbacks such as high energy consumption and high requirements for equipment corrosion resistance. Traditional ammonium sulfate slag treatment often relies on the addition of external alkali agents or high-temperature roasting conditions, resulting in high energy consumption, complex operation, and difficulty in adapting to multi-source modified raw materials. In recent years, with the rapid development of green functional materials and new energy storage materials industries, how to transform traditional metallurgical by-product waste slag into high-purity inorganic salts, magnetic materials, and photocatalytic materials for high-value applications has become an important breakthrough direction in the field of resource recycling. CN120590058A proposes a high-transparency rare-earth-doped fluoride glass and its preparation method, but it suffers from complex process flow, fluoride corrosion, and safety risks. Magnesium fluoride, as a key optical ceramic and electronic material, can be directly prepared from magnesium-containing systems via fluorination precipitation, possessing advantages such as structural stability, strong chemical inertness, and wide application range. Therefore, developing a process for the synergistic extraction of magnesium resources from ammonium sulfate slag, the cascade conversion of manganese resources, and the recovery of all components of ammonium sulfate will significantly improve the utilization efficiency of metallurgical by-products, construct a coupling path between waste resource utilization and advanced materials manufacturing, and has significant technical and economic value. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for the complete separation, purification and high-value utilization of ammonium sulfate slag waste, which solves the problems of high treatment cost, low resource utilization rate and complex material preparation process of ammonium sulfate slag.

[0005] Technical solution: The method for the complete separation, purification, and high-value utilization of ammonium sulfate slag waste according to the present invention includes the following steps: (1) Fluorination conversion: Dissolve ammonium sulfate residue in deionized water, add ammonium fluoride to react and obtain a suspension, then centrifuge to separate the conversion residue and conversion liquid; (2) Washing and purification: Add deionized water to the conversion residue obtained in step (1), stir and centrifuge to obtain purified washing residue; (3) Drying: The purified washing residue obtained in step (2) is dried to obtain MgF2 product; (4) Extraction: Saponify the extractant first and then add the diluent to obtain the extract. Mix and extract the extract with the conversion liquid obtained in step (1) to obtain the organic phase and the raffinate, respectively. (5) Evaporation and crystallization: Evaporate and crystallize the raffinate obtained in step (4) to obtain (NH4)2SO4 product; Back-extraction: Add nitric acid to the manganese-containing organic phase obtained in step (4) for back-extraction, separate the phases, and obtain back-extraction liquid and extractant. The extractant is recycled. (6) Preparation of sol-gel materials: Add ferric nitrate and citric acid to the back-extraction solution obtained in step (5) and react to obtain manganese magnesium ferrite precursor; (7) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (6) is calcined to obtain Mn x Mg 1-x Fe2O4 (x = 0-50%) material.

[0006] Preferably, in step (1), the liquid-to-solid ratio (ml / g) of deionized water to ammonium sulfate residue is 1 to 8, and the amount of ammonium fluoride added is 0.4 to 1.2 times the theoretical amount of MgF2 generated; in step (6), the amount of ammonium fluoride added is stoichiometric (Mn 2+ +Mg 2+ ):Fe 3+ The ratio of ferric nitrate is 1:1.9 to 1:2.1, preferably 1:2.

[0007] Preferably, in step (1), the reaction temperature is 20 ~ 70 ℃ and the reaction time is 20 ~ 100 min.

[0008] More preferably, in step (1), the reaction temperature is 30 ~ 50 ℃ and the reaction time is 40 ~ 60 min.

[0009] More preferably, in step (1), the centrifugation speed is 1000 ~ 8000 r / min.

[0010] Preferably, the extractant is P204, C272 or N235.

[0011] More preferably, the extractant is P204.

[0012] Preferably, in step (4), the diluent is sulfonated kerosene.

[0013] In a further preferred embodiment, in step (2), deionized water with a liquid-to-solid ratio of 10:1 is added to the washing residue and stirred at room temperature for 10 min.

[0014] In a further preferred embodiment, in step (3), the washing residue is dried in a blower drying oven at 70 °C for 8 hours.

[0015] Preferably, in step (4), the extractant is first saponified with a 2-4 mol / L sodium hydroxide solution until the saponification rate is 10-60%; a diluent is added and mixed, with the volume fraction of extractant to diluent being 10-60%; the volume ratio of extractant to conversion liquid is 0.5-4; and primary extraction is performed at room temperature for 5-15 min. More preferably, the concentration of sodium hydroxide solution is 3 mol / L; and primary extraction is performed at room temperature for 10 min.

[0016] Preferably, in step (5), nitric acid with a concentration of 2-4 mol / L is added to the manganese-containing organic phase, and back-extracted at room temperature for 5-15 min, with a phase separation time of 3-10 min. More preferably, nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase, and back-extracted at room temperature for 10 min, with a phase separation time of 5 min.

[0017] In a further preferred embodiment, in step (5), the raffinate obtained in step (4) is heated to 80 °C to evaporate and crystallize, thereby obtaining the (NH4)2SO4 product.

[0018] Preferably, in step (6), citric acid is added in a ratio of 1:2 to 1:5 of all metals by mass.

[0019] Preferably, step (6) further includes adjusting the pH to 7 to 12 with ammonia and continuously heating at 40 to 120 °C for 2 to 10 h to carry out the reaction.

[0020] Preferably, in step (7), the calcination process requires continuous heating at 450 ~ 800 ℃ for 2 ~ 10 h.

[0021] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: This invention proposes a method for high-value utilization of multiple components from ammonium sulfate slag based on a synergistic strategy of fluorination conversion, extraction-crystallization, and sol-gel-high-temperature calcination. Using ammonium sulfate slag as raw material, this invention introduces inexpensive ammonium fluoride as a precipitant through a one-step fluorination conversion, selectively precipitating high-purity MgF2 products. This method achieves efficient product synthesis at relatively low temperatures, eliminating the need for complex heat treatment and high-pressure equipment; and it separates Mn based on an extraction-back-extraction process. 2+ Mg 2+ High-value preparation of Mn x Mg 1-x Fe2O4 materials; and direct recovery of ammonium sulfate. This achieves high-value recovery of all components of key resources such as ammonia nitrogen, manganese, magnesium, and sulfur, featuring simple process, high resource conversion efficiency, environmental friendliness, and significant cost advantages. The prepared magnesium fluoride is applicable to optical materials and electronic ceramics; Mn x Mg 1-x Fe2O4 possesses excellent magnetic and photocatalytic properties for degrading organic pollutants; the recovered ammonium sulfate can be directly used as a nitrogen fertilizer raw material, realizing the synergistic high-value utilization of multiple components and fully demonstrating the systematic and practical value of comprehensive utilization of waste residue. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method for the complete separation, purification, and high-value utilization of ammonium sulfate residue waste. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings, embodiments, and comparative examples.

[0024] Example 1

[0025] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 4, the amount of ammonium fluoride added was 0.8 times the theoretical amount of MgF2 generated, the reaction temperature was 30 ℃, the reaction time was 40 min, and the centrifuge speed was 6000 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 20% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 30%, and the ratio of P204 to conversion liquid is 2. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 + The precursor of manganese magnesium ferrite was obtained by adjusting the pH to 8 with ferric nitrate (1:2 ratio), citric acid (metal:citric acid ratio of 1:3 ratio), and heating continuously at 85 °C for 6 h. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 500 °C for 4 h to obtain Mn x Mg 1-x Fe2O4 material.

[0026] The magnesium conversion rate was 78.86%, and the purity of the obtained MgF2 product was 99.14%, which meets the industry standard YS / T 691-2009 "Magnesium Fluoride"; the purity of the (NH4)2SO4 product was 98.93%, which meets the industry standard HG / T 5744-2020 "Industrial Ammonium Sulfate"; Mn can be prepared. 0.6 Mg 0.4 Fe2O4 material.

[0027] Example 2

[0028] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 3.5, the amount of ammonium fluoride added was 0.9 times the theoretical amount of MgF2 generated, the reaction temperature was 50 ℃, the reaction time was 50 min, and the centrifuge speed was 6500 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 30% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 20%, and the ratio of P204 to conversion liquid is 3. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 + Ferric nitrate at a ratio of 1:1.9 was added by mass of all metals; citric acid at a ratio of 1:3.5 was added; the pH was adjusted to 7.5 with ammonia; and the mixture was heated continuously at 80 °C for 6 h to obtain the manganese-magnesium ferrite precursor. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 500 °C for 4.5 h to obtain Mn x Mg 1-x Fe2O4 material.

[0029] The magnesium conversion rate was 89.86%, and the purity of the obtained MgF2 product was 99.27%, which meets the industry standard YS / T 691-2009 "Magnesium Fluoride"; the purity of the (NH4)2SO4 product was 98.89%, which meets the industry standard HG / T 5744-2020 "Industrial Ammonium Sulfate"; Mn can be prepared. 0.7 Mg 0.3 Fe2O4 material.

[0030] Example 3

[0031] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 1, the amount of ammonium fluoride added was 0.4 times the theoretical amount of MgF2 generated, the reaction temperature was 20 ℃, the reaction time was 100 min, and the centrifuge speed was 5500 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 60% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 60%, and the ratio of P204 to conversion liquid is 3. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 + The manganese magnesium ferrite precursor was obtained by adding all metals in a 1:2 ratio of ferric nitrate and citric acid in a 1:3 ratio of citric acid, adjusting the pH to 8 with ammonia, and heating continuously at 75 °C for 7 h. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 550 °C for 10 h to obtain Mn x Mg 1-x Fe2O4 material.

[0032] The magnesium conversion rate was 35.67%, which was low due to insufficient ammonium fluoride addition and a low liquid-to-solid ratio. The obtained MgF2 product had a purity of 99.08%, conforming to the YS / T 691-2009 industry standard for magnesium fluoride. The (NH4)2SO4 product had a purity of 99.17%, conforming to the HG / T 5744-2020 industry standard for industrial ammonium sulfate. Mn can be prepared.0.7 Mg 0.3 Fe2O4 material.

[0033] Example 4

[0034] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 8, the amount of ammonium fluoride added was 1.2 times the theoretical amount of MgF2 generated, the reaction temperature was 50 ℃, the reaction time was 40 min, and the centrifuge speed was 5000 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 10% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 10%, and the ratio of P204 to conversion liquid is 2. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 + Ferric nitrate in a 1:2.1 ratio was added by mass of all metals; citric acid in a 1:3.5 ratio was added; the pH was adjusted to 7 with ammonia; and the mixture was heated continuously at 85 °C for 4.5 h to obtain the manganese-magnesium ferrite precursor. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 450 °C for 2 h to obtain Mn x Mg 1-x Fe2O4 material.

[0035] The magnesium conversion rate was 99.97%, and the purity of the obtained MgF2 product was 79.12%; the purity of the (NH4)2SO4 product was 52.87%, mainly because the saponification of P2O4 was low in volume fraction, and Mn and Mg could not be extracted; MnFe2O4 material can be prepared.

[0036] Example 5

[0037] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 2, the amount of ammonium fluoride added was 0.9 times the theoretical amount of MgF2 generated, the reaction temperature was 35 ℃, the reaction time was 55 min, and the centrifuge speed was 5000 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 40% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 50%, and the ratio of P204 to conversion liquid is 2. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 + The manganese magnesium ferrite precursor was obtained by adding all metals in a 1:2 ratio of ferric nitrate and citric acid in a 1:3.5 ratio, adjusting the pH to 7.5 with ammonia, and heating continuously at 80 °C for 6 h. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 600 °C for 5 h to obtain Mn x Mg 1-xFe2O4 material.

[0038] The magnesium conversion rate was 57.91%, and the purity of the obtained MgF2 product was 99.18%, which meets the industry standard YS / T 691-2009 "Magnesium Fluoride". The low magnesium conversion rate was due to the low liquid-to-solid ratio, which prevented the ammonium sulfate slag from dissolving, making the reaction difficult to proceed. The purity of the (NH4)2SO4 product was 99.21%, which meets the industry standard HG / T 5744-2020 "Industrial Ammonium Sulfate". Mn can be prepared. 0.5 Mg 0.5 Fe2O4 material.

[0039] Comparative Example 1

[0040] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 8, the amount of ammonium fluoride added was 1.5 times the theoretical amount of MgF2 generated, the reaction temperature was 50 ℃, the reaction time was 60 min, and the centrifuge speed was 6000 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 20% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 30%, and the ratio of P204 to conversion liquid is 2. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 +The manganese magnesium ferrite precursor was obtained by adding all metals in a 1:2 ratio of ferric nitrate and citric acid in a 1:3 ratio by mass, adjusting the pH to 7.5 with ammonia, and heating continuously at 85 °C for 4.5 h. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 550 °C for 5 h to obtain Mn x Mg 1-x Fe2O4 material.

[0041] The magnesium conversion rate was 99.92%, and the purity of the obtained MgF2 product was 64.28%, which did not meet the industry standard YS / T 691-2009 "Magnesium Fluoride". The main reason was that the amount of NH4F added was too large, which reacted to form MnF2, resulting in a decrease in product purity. The purity of the (NH4)2SO4 product was 99.02%, which met the industry standard HG / T 5744-2020 "Industrial Ammonium Sulfate". MnF2 cannot be prepared. x Mg 1-x The main reason why Fe2O4 material can be used to prepare MnFe2O4 is that the amount of NH4F added is too large, and the amount of Mg in the solution is too high. 2+ The concentration is very low, which is due to the absence of magnesium.

[0042] Comparative Example 2

[0043] Follow these steps to recycle: (1) Fluorination conversion: A certain amount of ammonium sulfate residue was dissolved in deionized water, and a certain amount of ammonium fluoride was added to react and the solid-liquid separation was carried out using a centrifuge. The liquid-solid ratio (ml / g) of deionized water to ammonium sulfate residue was 8, the amount of ammonium fluoride added was 0.9 times the theoretical amount of MgF2 generated, the reaction temperature was 70 ℃, the reaction time was 60 min, and the centrifuge speed was 5000 r / min. (2) Washing and purification: The conversion residue obtained in step (1) is washed and purified. Deionized water with a liquid-to-solid ratio of 10:1 is added to the conversion residue. After stirring at room temperature for 10 min, the residue is separated by centrifugation to obtain the washing residue. (3) Drying: The washing residue obtained in step (2) is dried in a forced-air drying oven at 70 °C for 8 hours to obtain MgF2 product; (4) Extraction: The conversion liquid obtained in step (1) is extracted. P204 is first saponified to 30% with 3 mol / L sodium hydroxide solution. The volume fraction of P204 to sulfonated kerosene is 20%, and the ratio of P204 to conversion liquid is 2. The first-stage extraction is carried out at room temperature for 10 min to obtain organic phase and raffinate. (5) Evaporation and crystallization: The raffinate obtained in step (4) is heated to 80 °C for evaporation and crystallization to obtain (NH4)2SO4 product; (6) Back-extraction of manganese: The organic phase obtained in step (4) is back-extracted. Nitric acid with a concentration of 3 mol / L is added to the manganese-containing organic phase. Back-extraction is carried out at room temperature for 10 min, and the phase separation time is 5 min to obtain back-extraction solution and P204. P204 is recycled. (7) Preparation of sol-gel materials: Add stoichiometric amounts of Mn to the back-extraction solution obtained in step (6). 2+ +Mg 2+ ):Fe 3 + The metals were added in a 1:1 ratio of ferric nitrate by mass, and the citric acid was adjusted to 1:1. The pH was adjusted to 12 with ammonia, and the mixture was heated continuously at 120 °C for 10 h to obtain the manganese-magnesium ferrite precursor. (8) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (7) is continuously heated at 550 °C for 5 h to obtain Mn x Mg 1-x Fe2O4 material.

[0044] The magnesium conversion rate was 89.37%, and the purity of the obtained MgF2 product was 99.84%, which meets the industry standard YS / T 691-2009 "Magnesium Fluoride". The low magnesium conversion rate was due to the low liquid-to-solid ratio, which prevented the ammonium sulfate slag from dissolving, making the reaction difficult to proceed. The purity of the (NH4)2SO4 product was 99.21%, which meets the industry standard HG / T 5744-2020 "Industrial Ammonium Sulfate". Mn cannot be prepared. x Mg 1-x The main reason for the poor performance of Fe2O4 material is that the amount of ferric nitrate and citric acid added is too small, so they cannot form a sol-gel, and the pH adjustment with ammonia water is too high, forming hydroxides.

Claims

1. A method for the complete separation, purification, and high-value utilization of ammonium sulfate slag waste, characterized in that, Includes the following steps: (1) Fluorination conversion: Dissolve ammonium sulfate residue in deionized water, add ammonium fluoride to react and obtain a suspension, then centrifuge to separate the conversion residue and conversion liquid; (2) Washing and purification: Add deionized water to the conversion residue obtained in step (1), stir and centrifuge to obtain purified washing residue; (3) Drying: The purified washing residue obtained in step (2) is dried to obtain MgF2 product; (4) Extraction: Saponify the extractant first and then add the diluent to obtain the extract. Mix and extract the extract with the conversion liquid obtained in step (1) to obtain the organic phase and the raffinate, respectively. (5) Evaporation and crystallization: Evaporate and crystallize the raffinate obtained in step (4) to obtain (NH4)2SO4 product; Back-extraction: Nitric acid is added to the manganese-containing organic phase obtained in step (4) for back-extraction, phase separation, and back-extraction solution and extractant are obtained. The extractant is recycled. (6) Preparation of sol-gel materials: Add ferric nitrate and citric acid to the back-extraction solution obtained in step (5) and react to obtain manganese magnesium ferrite precursor; (7) High-temperature calcination: The manganese-magnesium ferrite precursor obtained in step (6) is calcined to obtain Mn x Mg 1-x Fe2O4 (x=0-50%) material.

2. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (1), the liquid-to-solid ratio (ml / g) of deionized water to ammonium sulfate residue is 1-8, and the amount of ammonium fluoride added is 0.4-1.2 times the theoretical amount for the formation of MgF2; in step (6), stoichiometric amounts of Mn are added. 2+ +Mg 2+ ):Fe 3+ Ferric nitrate with a ratio of 1:1.9 to 1:2.

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3. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (1), the reaction temperature is 20 ~ 70 ℃ and the reaction time is 20 ~ 100 min.

4. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, The extractant is P204, C272 or N235.

5. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (4), the diluent is sulfonated kerosene.

6. The method for the complete separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (4), the extractant is first saponified with 2-4 mol / L sodium hydroxide solution until the saponification rate is 10-60%; a diluent is added and mixed, with the volume fraction of extractant to diluent being 10-60%; the volume ratio of extractant to conversion liquid is 0.5-4; and primary extraction is performed at room temperature for 5-15 min.

7. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (5), nitric acid with a concentration of 2-4 mol / L is added to the manganese-containing organic phase, and back-extracted at room temperature for 5-15 min, with a phase separation time of 3-10 min.

8. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (6), add citric acid in a ratio of 1:2 to 1:5 of all metals by mass.

9. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, Step (6) also includes adjusting the pH to 7 to 12 with ammonia and heating continuously at 40 to 120 °C for 2 to 10 h to carry out the reaction.

10. The method for the complete component separation, purification, and high-value utilization of ammonium sulfate slag waste according to claim 1, characterized in that, In step (7), the calcination process requires continuous heating at 450 ~ 800 ℃ for 2 ~ 10 h.

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