Method for synergistically utilizing desulfurized gypsum and fluorine-containing waste

Abstract

The invention relates to the technical field of resource utilization of industrial solid wastes, in particular to a method for synergistically utilizing desulfurized gypsum and fluorine-containing wastes. Aiming at the resource characteristics that the desulfurized gypsum contains rich calcium element and the fluorine-containing waste contains rich fluorine element, a mixture of the desulfurized gypsum and the fluorine-containing waste is used as a raw material, and the aim of synergistically utilizing the desulfurized gypsum and the fluorine-containing waste is fulfilled through a leaching-roasting-leaching-precipitation process under the assistance of a reaction aid. The method not only solves the problem of resource utilization of the desulfurized gypsum, but also converts the fluoride into calcium fluoride through reaction with the fluoride, reduces the concentration of soluble fluoride in the waste, further improves the overall resource utilization efficiency, improves the additional value of the desulfurized gypsum and the fluorine-containing waste, and reduces the environmental burden.

Description

Technical Field

[0001] The invention relates to the technical field of industrial solid waste resource utilization, and in particular to a method for coordinated utilization of desulfurized gypsum and fluorine-containing waste. Background Art

[0002] Desulfurized gypsum is a byproduct used to remove sulfur dioxide (SO2) from flue gas in coal-fired power plants and other industrial facilities. Its main component is gypsum (CaSO4.2H2O). With the implementation of environmental protection policies, the output of desulfurized gypsum has increased year by year and has become a waste. How to effectively utilize these desulfurized gypsum has become an important issue. If desulfurized gypsum is piled up in large quantities, it may cause environmental pollution, especially in humid conditions, where it may release harmful substances. Therefore, it is crucial to find effective ways to utilize it.

[0003] Fluoride-containing waste usually comes from industrial production processes such as chemical industry, mineral processing, metal smelting, etc., and contains a large amount of fluoride (such as fluoride, sodium fluoride, aluminum fluoride, etc.). This type of waste is extremely harmful to the environment and ecosystem. The treatment of fluoride-containing waste faces technical and economic difficulties. Direct treatment or disposal of these wastes usually requires high costs and brings the risk of secondary pollution.

[0004] By combining desulfurized gypsum with fluoride-containing waste and utilizing the calcium component in gypsum to react with fluoride, fluoride can be effectively removed from the waste and converted into harmless products such as calcium fluoride (CaF2). This method can not only reduce the environmental burden of desulfurized gypsum and fluoride-containing waste, but also achieve the recycling of fluorine resources. Through synergistic reactions, the utilization value of desulfurized gypsum can also be increased, and desulfurized gypsum can be converted into fluorite powder. At the same time, fluoride waste is utilized to eliminate its pollution to the environment and effectively utilize the fluorine and aluminum elements therein.

[0005] At present, the treatment of desulfurized gypsum is mainly concentrated in the fields of building materials and agriculture, while the treatment of fluorine-containing waste mainly relies on methods such as high-temperature incineration or acid-base leaching, such as patent document: CN102861235A "Desulfurized gypsum resource utilization method" This patent proposes a method for resource utilization of desulfurized gypsum, including modifying it through heat treatment and chemical reaction, so that it can play a greater role in applications in different fields, especially in terms of waterproofing and fire resistance. Patent document: CN103907368A "Fluorine-containing waste treatment method" This patent proposes a method for treating fluorine-containing waste, mainly by reacting with minerals to combine fluoride with the calcium component in the mineral and convert it into calcium fluoride (CaF2). This method effectively reduces the toxicity of fluoride and can convert waste into useful mineral resources. However, CN102861235A involves the resource utilization of desulfurized gypsum. Although the existing technology improves the utilization rate of desulfurized gypsum by heat treatment, it still faces the problems of low resource utilization rate and high environmental risk. CN103907368A describes the treatment technology of fluorine-containing waste, which treats fluorine-containing waste by reaction with minerals to reduce its pollution to the environment. However, this technology mainly focuses on the removal of fluoride and has not yet considered how to coordinate with desulfurized gypsum. Therefore, a new technology is needed to effectively coordinate the utilization of desulfurized gypsum and fluorine-containing waste, reduce environmental pollution and provide a sustainable treatment solution. Summary of the invention

[0006] The present invention aims at the resource characteristics that desulfurized gypsum contains rich calcium elements and fluorine-containing waste contains rich fluorine elements. With the mixture of desulfurized gypsum and fluorine-containing waste as raw materials, the present invention achieves the purpose of synergistic utilization of desulfurized gypsum and fluorine-containing waste through leaching-roasting-leaching-precipitation process with the assistance of reaction aids. It not only solves the resource utilization problem of desulfurized gypsum, but also converts fluoride into calcium fluoride through reaction with fluoride, reduces the concentration of soluble fluoride in the waste, thereby improving the overall resource utilization efficiency, increasing the added value of desulfurized gypsum and fluorine-containing waste, and reducing the environmental burden.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is:

[0008] The present invention provides a method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste, which is characterized by comprising the following steps:

[0009] Step 1: pre-dried desulfurized gypsum and fluorine-containing waste are mixed in proportion, and auxiliary agent 1 is added to grind and homogenize to obtain a synergistic raw material.

[0010] Step 2: Add water to the synergistic raw material to leach it, separate the solid and liquid, and obtain filter cake 1 and filtrate 1. The filtrate 1 is concentrated and crystallized to obtain sodium sulfate.

[0011] Step 3: the filter cake 1 is washed and dried, and the auxiliary agent 2 is added and ground and homogenized to obtain a mixed material, the mixed material is placed in a kiln for roasting, and a clinker is obtained after roasting. The clinker is leached with water, and the solid and liquid are separated to obtain a filter cake 2 and a filtrate 2. The filter cake 2 is washed and dried to obtain calcium fluoride.

[0012] Step 4: Add auxiliary agent 3 to filtrate 2 to react and generate white precipitate, separate solid and liquid to obtain filter cake 3 and filtrate 3, wash and dry filter cake 3 to obtain aluminum hydroxide, and concentrate filtrate 3 to crystallize to obtain sodium salt.

[0013] Furthermore, the auxiliary agent 1 described in step 1 is any one of tartaric acid, citric acid and oxalic acid, and the added amount is 3%-15% of the weight of the desulfurized gypsum, and the preferred added amount is 5%-10% of the weight of the desulfurized gypsum.

[0014] Furthermore, if the amount of additive 1 added is too low, its dispersing effect and the effect of promoting the dissolution of calcium sulfate are not obvious, and if the amount added is too high, the additive is wasted and the cost is increased.

[0015] Furthermore, the fluorine-containing waste material in step 1 comes from electrolytic aluminum and fluorine chemical industry, and preferably is selected from electrolytic aluminum fluorine-containing waste material, which may be any one of waste cryolite, waste carbon slag, waste electrolyte, and waste covering material.

[0016] Furthermore, the leaching temperature in step 2 is 40-90°C, the liquid-to-solid ratio is (10-30):1, and the preferred liquid-to-solid ratio is (15-20):1.

[0017] Furthermore, if the liquid-to-solid ratio is too small, the leaching effect of sodium fluoride in fluoride-containing waste is not ideal, and the reaction rate between sodium fluoride and calcium sulfate is low; if the liquid-to-solid ratio is too large, the solid-liquid separation load is large, the energy consumption is high, and the cost is increased.

[0018] Furthermore, the auxiliary agent 2 in step 3 is sodium carbonate, and the added amount is 50%-100% of the weight of the desulfurized gypsum.

[0019] Furthermore, the auxiliary agent 2 in step 3 may also be sodium bicarbonate, and the added amount of sodium bicarbonate is 80%-160% of the weight of the desulfurized gypsum. The auxiliary agent 2 preferably uses sodium carbonate.

[0020] Furthermore, the calcination temperature in step 3 is 700-1000° C., and the calcination time is 1.0-4.0 h. The preferred calcination temperature is 800-900° C., and the calcination time is 1.5-3.0 h.

[0021] Furthermore, the main chemical reaction occurring during the roasting process described in step 3 is:

[0022] 3CaSO4+Na3AlF6+2Na2CO3→3Na2SO4+3CaF2+NaAlO2+2CO2(g) (1)

[0023] 7CaSO4+Na5Al3F 14 +6Na2CO3→7Na2SO4+7CaF2+3NaAlO2+6CO2(g) (2)

[0024] CaSO4+2NaF→Na2SO4+CaF2 (3)

[0025] Furthermore, the leaching temperature in step 3 is room temperature, the liquid-solid ratio is (5-15): 1, and the preferred liquid-solid ratio is (8-12): 1. Furthermore, the filtrate 2 in step 3 is a sodium aluminate solution.

[0026] Furthermore, in step 3, the filter cake 2 is washed with dilute hydrochloric acid, the purpose of which is to remove the aluminum oxide in the filter cake 2 and obtain pure calcium fluoride.

[0027] Furthermore, the yield of calcium fluoride in step 3 is 56% to 57% of the weight of desulfurized gypsum, the purity is greater than 98.5%, and the product quality meets the first-class requirements of GB / T27804-2011.

[0028] Furthermore, if the liquid-to-solid ratio is too small, the separation effect of sodium sulfate, sodium aluminate and calcium fluoride is not ideal; if the liquid-to-solid ratio is too large, the solid-liquid separation load is large, the energy consumption is high, and the cost is increased.

[0029] Furthermore, the auxiliary agent 3 in step 4 is any one of aluminum chloride, aluminum sulfate, and aluminum nitrate, and the amount of auxiliary agent 3 added is 11%-17% of the weight of the desulfurized gypsum, and a saturated solution is pre-made for addition, wherein the amount of aluminum chloride added is 11%, the amount of aluminum sulfate added is 14%, and the amount of aluminum nitrate added is 17%.

[0030] Furthermore, the main reaction in step 4 is:

[0031] AlCl3+3NaAlO2+6H2O→4Al(OH)3↓+3NaCl (4)

[0032] Al(NO3)3+3NaAlO2+6H2O→4Al(OH)3↓+3NaNO3 (5)

[0033] Al2(SO4)3+6NaAlO2+12H2O→8Al(OH)3↓+3Na2SO4 (6)

[0034] Furthermore, the yield of aluminum hydroxide in step 4 is greatly affected by the type of fluorine-containing waste material, and is 49% to 98% of the weight of desulfurized gypsum. The yield is the highest when waste covering material is used, which is about 98%.

[0035] The positive beneficial effects of the present invention are:

[0036] 1. The wet-fire combined process is adopted to effectively utilize the calcium element of desulfurized gypsum and the fluorine element of fluorine-containing waste, and at the same time extract the aluminum element of fluorine-containing waste. The final main products are calcium fluoride and aluminum hydroxide, and the by-product is sodium salt. The reaction principle is shown in the chemical reaction equations (1) to (6). The reaction products of (1) to (3) are mainly calcium fluoride, sodium sulfate and sodium aluminate. When the product is soaked in water, sodium sulfate and sodium aluminate dissolve into the water. The filter cake obtained by solid-liquid separation contains only calcium fluoride, so the product is calcium fluoride; the reaction products of (4) to (6) are mainly aluminum hydroxide and sodium chloride / sodium nitrate / sodium sulfate. When the product is soaked in water, sodium chloride / sodium nitrate / sodium sulfate is very easy to dissolve into the water. The filter cake obtained by solid-liquid separation contains only aluminum hydroxide, so the product is aluminum hydroxide.

[0037] 2. Gypsum is sticky and easy to agglomerate. The role of additive 1 is to improve the dispersibility of gypsum and increase the solubility of calcium sulfate. The reaction between calcium sulfate and cryolite is a solid-solid reaction. Adding additive 2 releases gas during the reaction. The escape of gas makes the reaction product layer loose, promotes the mutual diffusion and contact between cryolite and calcium sulfate, and is conducive to the reaction to the right. The mechanism is: after Na2CO3 is added to the reaction system, under certain conditions, sodium carbonate will decompose and release carbon dioxide (CO2) gas. The released carbon dioxide gas can promote the contact and diffusion between the reactants through the escape process. This gas escape helps to improve the mass transfer process of the reaction, promote effective contact between the reactants, and thus accelerate the solid-solid reaction. That is, the released carbon dioxide gas not only helps to provide power, so that the reactants can contact better, but also may reduce the overall viscosity of the system in some cases, making the reacting solid particles easier to contact each other, thereby increasing the reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a process flow chart of the present invention;

[0039] Figure 2 is the XRD spectrum of the fluorite product of the present invention;

[0040] Figure 3 is the XRD pattern of the aluminum hydroxide product of the present invention;

[0041] Figure 4 This is the SEM spectrum of the fluorite product of the present invention;

[0042] Figure 5 This is the EDS spectrum of the fluorite product of the present invention. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the technical solution and implementation effect of the present invention, the method for coordinated utilization of desulfurized gypsum and fluorine-containing waste of the present invention is further described in detail below in combination with specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0044] Example 1

[0045] A method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste materials comprises the following steps:

[0046] Step 1: pre-dried desulfurized gypsum and waste electrolyte are mixed in a weight ratio of 2:1, 6% tartaric acid is added, and the mixture is ground and homogenized to obtain a synergistic raw material.

[0047] Step 2: The synergistic raw material is leached with water, the liquid-to-solid ratio is 25:1, and the leaching temperature is 60°C. During the leaching process, part of the calcium sulfate reacts chemically with the sodium fluoride to generate calcium fluoride and sodium sulfate. The solid and liquid are separated to obtain filter cake 1 and filtrate 1. The filtrate 1 is concentrated and crystallized to obtain sodium sulfate.

[0048] Step 3: the filter cake 1 is washed and dried, sodium carbonate accounting for 60% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a mixture, which is placed in a kiln for roasting at a temperature of 900°C and a holding time of 2 hours. After roasting, clinker is obtained, and the clinker is leached with water at a liquid-solid ratio of 8:1. The solid and liquid are separated to obtain filter cake 2 and filtrate 2. The filter cake 2 is washed and dried to obtain calcium fluoride with a purity greater than 98.5%. The product quality meets the first-class requirements of GB / T27804-2011.

[0049] Step 4: add aluminum chloride (pre-prepared as a saturated solution) accounting for 11% of the weight of the desulfurized gypsum to the filtrate 2, react to generate a white precipitate, separate the solid and liquid, and obtain filter cake 3 and filtrate 3. Wash and dry the filter cake 3 to obtain aluminum hydroxide (the product meets the requirements of GB / T4292-2010 AH-2), and concentrate and crystallize the filtrate 3 to obtain sodium chloride.

[0050] Example 2

[0051] A method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste materials comprises the following steps:

[0052] Step 1: pre-dried desulfurized gypsum and waste cryolite are mixed in a weight ratio of 2:0.9, oxalic acid accounting for 3% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a synergistic raw material.

[0053] Step 2: The synergistic raw material is leached with water, the liquid-to-solid ratio is 30:1, and the leaching temperature is 70°C. During the leaching process, part of the calcium sulfate reacts chemically with the sodium fluoride to generate calcium fluoride and sodium sulfate. The solid and liquid are separated to obtain filter cake 1 and filtrate 1. The filtrate 1 is concentrated and crystallized to obtain sodium sulfate.

[0054] Step 3: the filter cake 1 is washed and dried, sodium carbonate accounting for 50% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a mixture, which is placed in a kiln for roasting at a temperature of 1000°C and a holding time of 1h. After roasting, clinker is obtained, and the clinker is leached with water at a liquid-solid ratio of 10:1. The solid and liquid are separated to obtain filter cake 2 and filtrate 2. The filter cake 2 is washed and dried to obtain calcium fluoride with a purity greater than 98.5%. The product quality meets the first-class requirements of GB / T27804-2011.

[0055] Step 4: Add aluminum sulfate (pre-prepared as a saturated solution) accounting for 14% of the weight of the desulfurized gypsum to the filtrate 2, react to generate a white precipitate, separate the solid and the liquid, and obtain filter cake 3 and filtrate 3. Wash and dry the filter cake 3 to obtain aluminum hydroxide (the product meets the requirements of GB / T4292-2010 AH-2), and concentrate and crystallize the filtrate 3 to obtain sodium sulfate.

[0056] Example 3

[0057] A method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste materials comprises the following steps:

[0058] Step 1: pre-dried desulfurized gypsum and waste carbon slag (anode carbon slag) are mixed in a weight ratio of 2:1.4, citric acid accounting for 9% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a synergistic raw material.

[0059] Step 2: Add water to the synergistic raw material for leaching, with a liquid-to-solid ratio of 20:1 and a leaching temperature of 80°C. During the leaching process, part of the calcium sulfate reacts chemically with the sodium fluoride to generate calcium fluoride and sodium sulfate. The solid and liquid are separated to obtain filter cake 1 and filtrate 1. The filtrate 1 is concentrated and crystallized to obtain sodium sulfate.

[0060] Step 3: the filter cake 1 is washed and dried, sodium carbonate accounting for 70% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a mixture, which is placed in a kiln for roasting at a temperature of 800°C and a holding time of 3 hours. After roasting, clinker is obtained, and the clinker is leached with water at a liquid-solid ratio of 12:1. The solid and liquid are separated to obtain filter cake 2 and filtrate 2. The filter cake 2 is washed and dried to obtain calcium fluoride with a purity greater than 98.5%. The product quality meets the first-class requirements of GB / T27804-2011.

[0061] Step 4: Add aluminum nitrate (pre-prepared as a saturated solution) accounting for 17% of the weight of the desulfurized gypsum to the filtrate 2, react to generate a white precipitate, separate the solid and the liquid, and obtain filter cake 3 and filtrate 3. Wash and dry the filter cake 3 to obtain aluminum hydroxide (the product meets the requirements of GB / T4292-2010 AH-2), and concentrate and crystallize the filtrate 3 to obtain sodium nitrate.

[0062] Example 4

[0063] A method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste materials comprises the following steps:

[0064] Step 1: pre-dried desulfurized gypsum and waste covering material are mixed in a weight ratio of 2:1.8, citric acid accounting for 12% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a synergistic raw material.

[0065] Step 2: Add water to the synergistic raw material for leaching, with a liquid-to-solid ratio of 25:1 and a leaching temperature of 40°C. During the leaching process, part of the calcium sulfate reacts chemically with the sodium fluoride to generate calcium fluoride and sodium sulfate. The solid and liquid are separated to obtain filter cake 1 and filtrate 1. The filtrate 1 is concentrated and crystallized to obtain sodium sulfate.

[0066] Step 3: Filter cake 1 is washed and dried, sodium carbonate accounting for 100% of the weight of desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a mixture, which is placed in a kiln for roasting at a temperature of 700°C and a holding time of 4 hours. Clinker is obtained after roasting, and the clinker is leached with water at a liquid-solid ratio of 15:1. The solid and liquid are separated to obtain filter cake 2 and filtrate 2. Filter cake 2 is washed and dried to obtain calcium fluoride with a purity greater than 98.5%. The product quality meets the first-class requirements of GB / T27804-2011.

[0067] Step 4: add aluminum chloride accounting for 11% of the weight of desulfurized gypsum to the filtrate 2, react to generate a white precipitate, separate the solid and liquid, and obtain filter cake 3 and filtrate 3. Wash and dry the filter cake 3 to obtain aluminum hydroxide (the product meets the requirements of GB / T4292-2010 AH-2), and concentrate and crystallize the filtrate 3 to obtain sodium chloride.

[0068] Example 5

[0069] A method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste materials comprises the following steps:

[0070] Step 1: pre-dried desulfurized gypsum and waste carbon slag (mixed carbon slag) are mixed in a weight ratio of 2:2.4, tartaric acid accounting for 15% of the weight of the desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a synergistic raw material.

[0071] Step 2: The synergistic raw material is leached with water, the liquid-to-solid ratio is 30:1, and the leaching temperature is 90°C. During the leaching process, part of the calcium sulfate reacts chemically with the sodium fluoride to generate calcium fluoride and sodium sulfate. The solid and liquid are separated to obtain filter cake 1 and filtrate 1. The filtrate 1 is concentrated and crystallized to obtain sodium sulfate.

[0072] Step 3: Filter cake 1 is washed and dried, sodium carbonate accounting for 80% of the weight of desulfurized gypsum is added, and the mixture is ground and homogenized to obtain a mixture, which is placed in a kiln for roasting at a temperature of 850°C and a holding time of 2.5 hours. Clinker is obtained after roasting, and the clinker is leached with water at a liquid-solid ratio of 5:1. Solid-liquid separation is performed to obtain filter cake 2 and filtrate 2. Filter cake 2 is washed and dried to obtain calcium fluoride with a purity greater than 98.5%. The product quality meets the first-class requirements of GB / T27804-2011.

[0073] Step 4: Add aluminum sulfate accounting for 14% of the weight of desulfurized gypsum to the filtrate 2, react to generate a white precipitate, separate the solid and liquid, and obtain filter cake 3 and filtrate 3. Wash and dry the filter cake 3 to obtain aluminum hydroxide (the product meets the requirements of GB / T4292-2010 AH-2), and concentrate and crystallize the filtrate 3 to obtain sodium chloride.

[0074] The process and product indicators of the present invention are shown in the following table.

[0075]

[0076]

Claims

1. A method for the coordinated utilization of desulfurized gypsum and fluorine-containing waste, characterized in that: The following steps are involved: S1: Mix desulfurized gypsum and fluorine-containing waste in proportion, add auxiliary agent 1, grind and homogenize, and obtain a synergistic raw material; S2: adding water to the synergistic raw material to leach, separating the solid and the liquid to obtain filter cake 1 and filtrate 1, and concentrating and crystallizing the filtrate 1 to obtain sodium sulfate; S3: washing and drying the filter cake 1, adding the auxiliary agent 2, grinding and homogenizing to obtain a mixed material, adding water to leach after roasting, and separating the solid and liquid to obtain the filter cake 2 and the filtrate 2, and washing and drying the filter cake 2 to obtain calcium fluoride; S4: Adding auxiliary agent 3 to filtrate 2 to react and generate white precipitate, and performing solid-liquid separation to obtain filter cake 3 and filtrate 3. Filter cake 3 is washed and dried to obtain aluminum hydroxide, and filtrate 3 is concentrated and crystallized to obtain sodium salt.

2. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The auxiliary agent 1 described in S1 is any one of tartaric acid, citric acid and oxalic acid, and the added amount is 3%-15% of the weight of the desulfurized gypsum.

3. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The fluorine-containing waste materials described in S1 come from electrolytic aluminum and fluorine chemical industry, including any one of waste cryolite, waste carbon slag, waste electrolyte and waste covering material.

4. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The leaching temperature described in S2 is 40-90°C, and the liquid-to-solid ratio is (10-30):

1.

5. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The auxiliary agent 2 in S3 is sodium carbonate, and the added amount is 50%-100% of the weight of the desulfurized gypsum.

6. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The calcination temperature in S3 is 700-1000°C, and the calcination time is 1-4h.

7. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The main chemical reactions occurring during the calcination process described in S3 are: 3CaSO4+Na3AlF6+2Na2CO3→3Na2SO4+3CaF2+NaAlO2+2CO2(g) <h2 style=";text-align:left;direction:ltr">7CaSO4+Na5Al3F<h2 style=";text-align:left;direction:ltr"> 14 <h2 style=";text-align:left;direction:ltr"> +6Na2CO3→7Na2SO4+7CaF2+3NaAlO2+6CO2(g) CaSO4+2NaF→Na2SO4+CaF2.

8. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste materials according to claim 1, characterized in that: The leaching temperature in S3 is room temperature, and the liquid-to-solid ratio is (5-15):1; the filtrate 2 in S3 is a sodium aluminate solution.

9. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste materials according to claim 1, characterized in that: S4: the auxiliary agent 3 is any one of aluminum chloride, aluminum sulfate and aluminum nitrate, and the amount of the auxiliary agent 3 added is 11%-17% of the weight of the desulfurized gypsum.

10. The method for synergistic utilization of desulfurized gypsum and fluorine-containing waste according to claim 1, characterized in that: The main reactions in S4 are: AlCl3+3NaAlO2+6H2O→4Al(OH)3↓+3NaCl Al(NO3)3+3NaAlO2+6H2O→4Al(OH)3↓+3NaNO3 Al2(SO4)3+6NaAlO2+12H2O→8Al(OH)3↓+3Na2SO4.

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