Oxidation method of sulfite radicals in desulfurized gypsum
By adding carbonate to the desulfurized gypsum slurry and performing gas oxidation treatment, the problem of difficulty in oxidizing sulfite in the desulfurized gypsum is solved, and efficient oxidation and product recycling are achieved, which has economic and environmentally friendly advantages.
Patent Information
- Application Number
- CN202411727947.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-02-28
AI Technical Summary
There is a lack of suitable methods in the prior art to oxidize the sulfite present in the desulfurization gypsum, making it difficult to treat and reuse.
By adding carbonate to the desulfurized gypsum slurry, it is converted into sulfites that are easily oxidized and oxidized by gases to form sulfates, and finally obtaining the available sulfites by heating crystallization.
It has achieved efficient oxidation of sulfite in desulfurized gypsum, solved the problem of difficulty in dealing with it, and recycled the oxidized products, avoided secondary pollution, and has economic and environmentally friendly advantages.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of sulfite oxidation, and in particular to a method for oxidizing sulfite in desulfurized gypsum. Background Art
[0002] my country is one of the countries with the largest sulfur dioxide gas emissions in the world. Currently, the only large-scale commercial desulfurization method in the world is flue gas desulfurization. Flue gas desulfurization technologies can be roughly divided into dry, semi-dry and wet methods, and all of them will produce a large amount of desulfurization by-products - desulfurization gypsum. Due to the complex composition of desulfurization gypsum, it mainly includes calcium sulfate, unoxidized hemihydrate calcium sulfite and calcium carbonate. Among them, calcium sulfite is easy to decompose at high temperature and is harmful, which makes it difficult to reuse desulfurization gypsum. It is often treated by stacking. Therefore, seeking an efficient and simple method to force the oxidation of hemihydrate calcium sulfite is a key issue in the reuse of desulfurization gypsum.
[0003] Because the oxidation conditions of calcium sulfite in desulfurization gypsum are extremely harsh and there is currently no suitable oxidation method, it is necessary to develop an economical and simple conversion route that can not only easily oxidize the sulfite, but also recycle the subsequent products after oxidation. Summary of the invention
[0004] The present invention is intended to provide a method for oxidizing sulfite in desulfurized gypsum, so as to solve the problem that there is no suitable method for oxidizing sulfite in desulfurized gypsum.
[0005] In order to solve the above technical problems, the present invention provides the following technical solution: a method for oxidizing sulfite in desulfurized gypsum, comprising the following steps:
[0006] S1. Accurately weigh desulfurized gypsum and carbonate in a certain molar mass ratio, add them into water to form a slurry of a certain concentration, and stir in a water bath for a certain period of time to convert the desulfurized gypsum into calcium carbonate and water-soluble sulfites and sulfates;
[0007] S2, separating the slurry from step S1 into solid and liquid, adjusting the pH of the liquid phase, introducing gas to oxidize the sulfite to generate sulfate, and drying the solid phase to obtain calcium carbonate;
[0008] S3. The completely oxidized liquid phase is heated and crystallized, and then dried to obtain usable sulfate.
[0009] Furthermore, in step S1, the mass of carbonate accurately weighed is 1.01 to 5.00 times the molar mass of calcium sulfur in the desulfurized gypsum; carbonate includes but is not limited to ammonium carbonate, potassium carbonate, ammonium bicarbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate.
[0010] Furthermore, in step S1, the concentration of the slurry is 0.1 g / 100 ml to 100.0 g / 100 ml.
[0011] Furthermore, in step S1, the temperature of the water bath stirring is 10-100° C., the time is 10-300 min, and the stirring rate is 100-1000 r / min.
[0012] Furthermore, in step S2, the temperature of liquid phase oxidation after solid-liquid separation is 10-70°C, and the time is 0.5h-24h; the drying temperature of the solid phase is 60-100°C, and the time is 6-24h.
[0013] Furthermore, in step S2, the gas introduced into the liquid phase is air or oxygen, the gas flow rate is 0.3-5 L / min, and the pH of the liquid phase should be adjusted to 5-7.
[0014] Furthermore, in step S3, the evaporation crystallization temperature is 10-100° C., and the stirring rate is 100-1000 r / min.
[0015] The beneficial effects of the present invention are as follows: (1) The method of the present invention fully considers the presence of calcium sulfite in desulfurized gypsum and performs oxidation treatment on it, thereby solving the environmental problem that desulfurized gypsum is difficult to treat due to the presence of calcium sulfite; (2) The method of the present invention adds water-soluble carbonate to the desulfurized gypsum slurry to convert it into easily oxidizable sulfite, thereby solving the inherent problem that calcium sulfite in desulfurized gypsum is difficult to oxidize; (3) The method of the present invention introduces air or oxygen when oxidizing sulfite, thereby greatly reducing the oxidation cost and having economic advantages; (4) The desulfurized gypsum products treated by the method of the present invention can all be recycled without causing secondary pollution, calcium carbonate can be used again for desulfurization treatment, and the oxidized ammonium sulfate can also be used as a fertilizer, thereby turning desulfurized gypsum into treasure and improving the utilization value of desulfurized gypsum; (5) The method of the present invention is simple to operate, can be fully implemented on the existing industrial basis, is green and environmentally friendly, and has a high promotion value. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The present invention is a flow chart of a method for oxidizing sulfite in desulfurized gypsum. DETAILED DESCRIPTION
[0017] The following is further described in detail through specific implementation methods:
[0018] The embodiment is basically as shown in the attached Figure 1 As shown: A method for oxidizing sulfite in desulfurized gypsum, comprising the following steps:
[0019] S1. Accurately weigh desulfurized gypsum and carbonate in a certain molar mass ratio, accurately weigh the mass of carbonate to be 1.01 to 5.00 times the molar mass of calcium sulfur in the desulfurized gypsum, carbonates include but are not limited to ammonium carbonate, potassium carbonate, ammonium bicarbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, successively add them into water to form a slurry with a concentration of 0.1 g / 100 ml to 100.0 g / 100 ml, stir in a water bath for a certain period of time to convert the desulfurized gypsum into calcium carbonate and water-soluble sulfites and sulfates, the stirring temperature of the water bath is 10 to 100 ° C, the time is 10 to 300 min, and the stirring rate is 100 to 1000 r / min;
[0020] S2, the slurry of step S1 is subjected to solid-liquid separation, the temperature of liquid phase oxidation after solid-liquid separation is 10-70°C, and the time is 0.5h-24h; the drying temperature of the solid phase is 60-100°C, and the time is 6-24h. After the pH of the liquid phase is adjusted, gas is introduced to oxidize sulfite to generate sulfate. The gas introduced into the liquid phase is air or oxygen, and the gas flow rate is 0.3-5L / min. The pH of the liquid phase should be adjusted to 6, and calcium carbonate is obtained after the solid phase is dried;
[0021] S3. The completely oxidized liquid phase is heated and crystallized, the evaporation crystallization temperature is 10-100°C, and the stirring speed is 100-1000r / min. After drying, the usable sulfate is obtained.
[0022] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.
Claims
1. A method for oxidizing sulfite in desulfurized gypsum, characterized in that: The following steps are involved: S1. Accurately weigh desulfurized gypsum and carbonate in a certain molar mass ratio, add them into water to form a slurry of a certain concentration, and stir in a water bath for a certain period of time to convert the desulfurized gypsum into calcium carbonate and water-soluble sulfites and sulfates; S2, separating the slurry from step S1 into solid and liquid, adjusting the pH of the liquid phase, introducing gas to oxidize the sulfite to generate sulfate, and drying the solid phase to obtain calcium carbonate; S3. The completely oxidized liquid phase is heated and crystallized, and then dried to obtain usable sulfate.
2. The method for oxidizing sulfite in desulfurized gypsum according to claim 1, characterized in that: In step S1, the mass of carbonate accurately weighed is 1.01 to 5.00 times the molar mass of calcium sulfur in the desulfurized gypsum; the carbonate includes but is not limited to ammonium carbonate, potassium carbonate, ammonium bicarbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate.
3. The method for oxidizing sulfite in desulfurized gypsum according to claim 2, characterized in that: In the step S1, the concentration of the slurry is 0.1 g / 100 ml to 100.0 g / 100 ml.
4. The method for oxidizing sulfite in desulfurized gypsum according to claim 3, characterized in that: In the step S1, the temperature of the water bath stirring is 10-100°C, the time is 10-300 min, and the stirring rate is 100-1000 r / min.
5. The method for oxidizing sulfite in desulfurized gypsum according to claim 4, characterized in that: In the step S2, after solid-liquid separation, the temperature of liquid phase oxidation is 10-70°C, and the time is 0.5h-24h; the drying temperature of the solid phase is 60-100°C, and the time is 6-24h.
6. The method for oxidizing sulfite in desulfurized gypsum according to claim 5, characterized in that: In step S2, the gas introduced into the liquid phase is air or oxygen, the gas flow rate is 0.3-5 L / min, and the pH of the liquid phase should be adjusted to 5-7.
7. The method for oxidizing sulfite in desulfurized gypsum according to claim 6, characterized in that: In the step S3, the evaporation crystallization temperature is 10-100° C., and the stirring rate is 100-1000 r / min.