Method for recycling desulfurized gypsum
By adding water and ammonia to the desulfurization gypsum to produce light calcium carbonate and using it to absorb sulfur dioxide from industrial flue gas, the problems of waste of desulfurization gypsum resources and environmental pollution are solved, and the recycling of resources and low-carbon production are realized.
Patent Information
- Application Number
- CN202411270839.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2019-08-28
- Publication Date
- 2024-12-13
AI Technical Summary
The existing technology cannot effectively utilize desulfurization gypsum, resulting in waste of resources and environmental pollution, especially the consumption of limestone resources, which has not been solved.
By adding water and ammonia water to the desulfurization gypsum, carbon dioxide gas is introduced to react to produce light calcium carbonate, and then using light calcium carbonate to absorb sulfur dioxide in industrial flue gas, realizing the recycling of desulfurization gypsum.
The comprehensive utilization and recycling of desulfurized gypsum has been achieved, resource consumption has been reduced, carbon dioxide emissions have been reduced, treatment costs have been reduced, and the goal of low-carbon production has been achieved.
Abstract
Description
[0001] This invention patent application is a divisional application of a Chinese patent application with an application date of August 28, 2019, application number 201910799274.4, and invention name “A method for recycling desulfurized gypsum”. Technical Field
[0002] The invention relates to a method for recycling desulfurized gypsum, in particular to a method for producing light calcium carbonate using desulfurized gypsum and industrial flue gas as raw materials, and utilizing light calcium carbonate to absorb sulfur dioxide in the industrial flue gas, and belongs to the field of environmental science. Background Art
[0003] Sulfur dioxide is one of the main pollutants in the atmosphere. In severe cases, it can cause disasters such as acid rain, which will cause serious harm to the ecological environment and human social economy. With the country's control of the emission of sulfur oxides such as sulfur dioxide, flue gas desulfurization technology has received more and more attention. Desulfurization gypsum is a solid waste produced by coal-fired power plants and other coal-burning enterprises using dry and semi-dry methods to desulfurize flue gas using desulfurizers. It is a white and yellowish dry powder mixture composed of desulfurization reaction products, unreacted desulfurizers and flue fly ash. The currently commonly used lime desulfurization technology consumes a large amount of natural limestone mineral resources.
[0004] Currently, the treatment of desulfurized gypsum is mainly carried out based on its chemical composition. It is impossible to experiment with the recycling of desulfurized gypsum, and the problem of consumption of limestone resources at the source has not been solved. Summary of the invention
[0005] In order to solve the problems existing in the above-mentioned existing process technology, the purpose of the present invention is to provide a method for recycling desulfurized gypsum.
[0006] In order to achieve the above object, the present invention adopts the following technical solution:
[0007] A method for recycling desulfurized gypsum comprises the following steps:
[0008] 1) adding water to the desulfurized gypsum to obtain a solid-liquid mixture of the desulfurized gypsum;
[0009] 2) placing the solid-liquid mixture obtained in step 1) in a stirred reaction vessel, adding ammonia water and introducing carbon dioxide gas therein, reacting for 10-120 minutes at normal temperature and pressure to obtain a reaction product;
[0010] 3) filtering the reaction product obtained in step 2), evaporating and crystallizing the filtrate to obtain light calcium carbonate and ammonium sulfate;
[0011] 4) Take a certain mass of light calcium carbonate, add a certain amount of water, introduce simulated industrial flue gas at a certain rate, and react for 30-180 minutes at normal pressure and 50-250° C. to obtain a reaction product;
[0012] 5) The reaction product obtained in step 4) is filtered to obtain a desulfurized gypsum sample, thereby realizing the recycling of the desulfurized gypsum.
[0013] The amount of water added in the above step 1) is 5-15mL / g; the amount of ammonia water added in step 2) is 3-12mL / g, and the concentration of ammonia water is 1-6mol / L; the carbon dioxide gas introduced is flue gas discharged from industrial production, the main components of which are nitrogen, oxygen, carbon dioxide, etc., the content of carbon dioxide gas is 5-100%, and the ventilation rate is 0.1-3L / min; the solid product light calcium carbonate described in step 3) is directly used for flue gas desulfurization without washing or drying.
[0014] The amount of water added in the above step 4) is 3-25 mL / g; the main chemical components in the simulated flue gas are nitrogen, carbon dioxide, oxygen, sulfur dioxide, etc., the content of sulfur dioxide gas is less than 5%, and the ventilation rate is 0.1-1 L / min; during the desulfurization reaction, if the sulfur dioxide in the flue gas after desulfurization meets the emission standard, the desulfurized flue gas is directly used for the production of light calcium carbonate, and the flue gas that does not meet the emission standard is transported through a pipeline to continue to react with light calcium carbonate until the sulfur dioxide content meets the emission standard.
[0015] The beneficial effects of using the method of the present invention to treat desulfurized gypsum are as follows: 1) comprehensive utilization and recycling of desulfurized gypsum are achieved; 2) the entire treatment process is carried out at low temperature and normal pressure, which is relatively safe; 3) the treatment cost is low; 4) the carbon dioxide emitted by the enterprise is solidified, realizing low-carbon production; 5) the natural mineral resources required for lime desulfurization are saved. DETAILED DESCRIPTION
[0016] A method for recycling desulfurized gypsum of the present invention comprises the following steps:
[0017] 1) adding water to the desulfurized gypsum to obtain a solid-liquid mixture of the desulfurized gypsum;
[0018] Wherein, the amount of water added in step 1) is 5-15 mL / g.
[0019] 2) placing the solid-liquid mixture obtained in step 1) in a stirred reaction vessel, adding ammonia water and introducing carbon dioxide gas therein, reacting for 10-120 minutes at normal temperature and pressure to obtain a reaction product;
[0020] Among them, the amount of ammonia water added in step 2) is 3-12mL / g, and the concentration of ammonia water is 1-6mol / L; the carbon dioxide gas introduced is the flue gas discharged from industrial production, the main components of which are nitrogen, oxygen, carbon dioxide, etc., the content of carbon dioxide gas is 5-100%, and the ventilation rate is 0.1-3L / min.
[0021] 3) filtering the reaction product obtained in step 2), evaporating and crystallizing the filtrate to obtain light calcium carbonate and ammonium sulfate;
[0022] The solid product light calcium carbonate described in step 3) can be directly used in flue gas desulfurization without washing or drying.
[0023] 4) Take a certain mass of light calcium carbonate, add a certain amount of water, introduce simulated industrial flue gas at a certain rate, and react for 30-180 minutes at normal pressure and 50-250° C. to obtain a reaction product;
[0024] Among them, the amount of water added in step 4) is 3-25mL / g; the main chemical components in the simulated flue gas are nitrogen, carbon dioxide, oxygen, sulfur dioxide, etc., the content of sulfur dioxide gas is less than 5%, and the ventilation rate is 0.1-1L / min; during the desulfurization reaction, if the sulfur dioxide in the flue gas after desulfurization meets the emission standard, the desulfurized flue gas is directly used for the production of light calcium carbonate, and the flue gas that does not meet the emission standard is transported through a pipeline to continue to react with light calcium carbonate until the sulfur dioxide content meets the emission standard.
[0025] 5) The reaction product obtained in step 4) is filtered to obtain a desulfurized gypsum sample, thereby realizing the recycling of the desulfurized gypsum.
[0026] The technical solution of the present invention is further described in detail below through specific examples.
[0027] Example 1:
[0028] The main chemical components of the desulfurized gypsum in this embodiment are, by weight percentage: SO3 38%, CaO 32%, SiO 27%, and other 23%; the specific process is as follows:
[0029] 1) Take 10g of the above-mentioned desulfurized gypsum powder, add 40mL of water to prepare a solid-liquid mixture of desulfurized gypsum, then add 80mL of ammonia water to the solid-liquid mixture, and introduce gas, stir and react at 35°C for 55min, the gas flow rate is 210mL / min, the stirring speed is 400r / min, and the gas composition is 20% oxygen, 65% nitrogen, and 15% carbon dioxide; after the reaction is completed, stop introducing gas, filter the reaction product, evaporate the filtrate and crystallize to recover ammonium sulfate, and the filter cake is calcium carbonate.
[0030] 2) Take 10 g of the above calcium carbonate, add 80 mL of water to form a solid-liquid mixture of calcium carbonate, introduce gas, stir and react at 105° C. for 75 min, the gas flow rate is 130 mL / min, the stirring speed is 400 r / min, and the gas composition is 16% oxygen, 66% nitrogen, 14% carbon dioxide, and 4% sulfur dioxide; after the reaction is completed, stop introducing gas, filter the reaction product, and obtain a desulfurized gypsum product.
[0031] 3) The above process realizes the recycling of desulfurized gypsum.
[0032] Example 2
[0033] The main chemical components of the desulfurized gypsum in this embodiment are, by weight percentage: SO3 40%, CaO 34%, SiO 25%, and other 21%; the specific process is as follows:
[0034] 1) Take 20g of the above-mentioned desulfurized gypsum powder, add 93mL of water to prepare a solid-liquid mixture of desulfurized gypsum, then add 146mL of ammonia water to the solid-liquid mixture, and introduce gas, stir and react at 43°C for 78min, the gas flow rate is 340mL / min, the stirring speed is 350r / min, and the gas composition is 20% oxygen, 62% nitrogen, and 18% carbon dioxide; after the reaction is completed, stop introducing gas, filter the reaction product, evaporate the filtrate and crystallize to recover ammonium sulfate, and the filter cake is calcium carbonate.
[0035] 2) Take 15 g of the above calcium carbonate, add 93 mL of water to form a solid-liquid mixture of calcium carbonate, introduce gas, stir and react at 125° C. for 65 min, the gas flow rate is 175 mL / min, the stirring speed is 360 r / min, and the gas composition is 17% oxygen, 65% nitrogen, 15% carbon dioxide, and 3% sulfur dioxide; after the reaction is completed, stop introducing gas, filter the reaction product, and obtain a desulfurized gypsum product.
[0036] 3) The above process realizes the recycling of desulfurized gypsum.
Claims
1. A method for recycling desulfurized gypsum, comprising the following steps: 1) Add water to the desulfurized gypsum to obtain a solid-liquid mixture of the desulfurized gypsum; the amount of water added is 5-15 mL / g; 2) placing the solid-liquid mixture obtained in step 1) in a stirred reaction vessel, adding ammonia water and introducing carbon dioxide gas therein, reacting for 10-120 minutes at normal temperature and pressure to obtain a reaction product; in, The carbon dioxide gas introduced is flue gas discharged from industrial production, and its main components are nitrogen, oxygen and carbon dioxide; the amount of ammonia water added is 3-12mL / g, and the concentration of ammonia water is 1-6 mol / L; the content of carbon dioxide gas in the flue gas discharged from industrial production is 5-15%, and the ventilation rate is 0.1-3 L / min; 3) The reaction product obtained in step 2) is filtered and the filtrate is evaporated and crystallized to obtain light calcium carbonate and ammonium sulfate; 4) Take a certain mass of light calcium carbonate, add a certain amount of water, pass simulated industrial flue gas at a certain rate, and react for 30-180 min at normal pressure and 50-250 °C; obtain a reaction product; wherein the main chemical components in the simulated industrial flue gas are nitrogen, carbon dioxide, oxygen and sulfur dioxide, and the content of sulfur dioxide gas is less than 5%; during the reaction, if the sulfur dioxide in the simulated industrial flue gas meets the emission standard after detection, the flue gas after desulfurization is directly used for the production of light calcium carbonate in step 2), and the flue gas that does not meet the emission standard is transported through a pipeline to continue to react with light calcium carbonate until the sulfur dioxide content meets the emission standard; the amount of water added is 3-25 mL / g; the ventilation rate of the simulated industrial flue gas is 0.1-1 L / min; 5) The reaction product obtained in step 4) is filtered to obtain a desulfurized gypsum sample, thereby realizing the recycling of the desulfurized gypsum.
2. The preparation method according to claim 1, Features: The solid product light calcium carbonate described in step 3) can be directly used for flue gas desulfurization without washing or drying.
3. The preparation method according to claim 1 or 2, Features: The desulfurized gypsum recycling process only requires the addition of a small amount of ammonia water and produces ammonium sulfate as a by-product, thereby realizing the comprehensive utilization and recycling of the desulfurized gypsum. The entire process does not produce any solid waste by-products, and does not discharge wastewater and exhaust gas, thereby reducing the carbon dioxide emissions of flue gas desulfurization enterprises and realizing low-carbon production and tail-free emissions for related enterprises.