A red mud-based pretreatment agent for blast furnace gas and a preparation method and application thereof

Abstract

The application provides a red mud-based pretreatment agent for blast furnace gas and a preparation method and application thereof, and the pretreatment agent comprises the following components in parts of mass: 80-90 parts of red mud, 0.1-3 parts of a binder, 3-5 parts of an active component, 5-10 parts of an alkaline adjusting agent and 3-5 parts of water; the red mud is a Bayer red mud, wherein the content of calcium oxide is 10-15%, and the content of sodium oxide is 5-10%; the active component is one of potassium carbonate and potassium hydroxide. The red mud-based pretreatment agent for blast furnace gas can remove acid gases in blast furnace gas and realize organic sulfur conversion at the same time, the protection effect reaches 86-96% of that of a traditional aluminum-based dechlorination agent, the cost is only about 50% of that of the traditional aluminum-based dechlorination agent, high-value resource utilization of red mud solid waste is realized, and the red mud-based pretreatment agent has the advantages of simple process, low energy consumption, outstanding economic efficiency and environmental protection benefits and the like.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation, environmental protection, and resource recycling technology, specifically relating to the field of blast furnace gas purification, and particularly to a red mud-based pretreatment agent for blast furnace gas, its preparation method, and its application. Background Technology

[0002] Red mud is a highly alkaline industrial solid waste generated during the production of alumina. Approximately 1-2 tons of red mud are produced for every ton of alumina produced. my country's annual red mud production exceeds 100 million tons, but the comprehensive utilization rate is less than 20%, and the cumulative stockpile has exceeded 1.5 billion tons. Large-scale stockpiling can easily cause serious environmental damage. The resource utilization and high-value utilization of red mud has become an urgent problem to be solved by the industry.

[0003] In the field of blast furnace gas desulfurization, conventional processes typically employ a technical route of dechlorination—organic sulfur conversion—inorganic sulfur adsorption. The dechlorination stage generally uses aluminum-based or calcium-based dechlorinating agents. However, aluminum-based dechlorinating agents suffer from high costs, while calcium-based dechlorinating agents are only effective for acid removal and have no effect on organic sulfur removal, making it difficult to meet the demand for low-cost and efficient pretreatment of blast furnace gas.

[0004] Most existing pretreatment agents are designed only for the removal of acidic gases and do not have the dual pretreatment function of removing acid and organic sulfur. The process route is long and the treatment cost is high. At the same time, red mud itself is rich in alkaline components, which can be used to neutralize acidic gases. However, the existing technology has failed to effectively combine the resource utilization of red mud with the fine desulfurization pretreatment of blast furnace gas, which not only wastes solid waste resources but also fails to reduce the cost of gas purification.

[0005] In summary, existing dechlorination agents and pretreatment agents suffer from problems such as high cost, limited functionality, inability to simultaneously address acid removal and organic sulfur conversion, and low utilization rate of red mud resources, making it difficult to achieve both environmental and economic benefits at the same time. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention aims to provide a red mud-based pretreatment agent for blast furnace gas, its preparation method, and its application. This invention overcomes the shortcomings of existing blast furnace gas pretreatment agents, such as high cost, single function, and low organic sulfur conversion efficiency. At the same time, it realizes the high-value resource utilization of Bayer process red mud solid waste, significantly reduces material costs while ensuring pretreatment effect, simplifies the gas fine desulfurization process route, and balances environmental and economic benefits.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] The first aspect of this invention provides a red mud-based pretreatment agent for blast furnace gas, wherein the pretreatment agent comprises the following components by mass parts:

[0009] 80-90 parts red mud, 0.1-3 parts binder, 3-5 parts active ingredient, 5-10 parts alkaline regulator, and 3-5 parts water;

[0010] The red mud is Bayer process red mud, with a calcium oxide content of 10%~15% and a sodium oxide content of 5%~10%.

[0011] The active component is one of potassium carbonate and potassium hydroxide.

[0012] Furthermore, the alkalinity regulator is at least one of calcium hydroxide and sodium hydroxide.

[0013] Furthermore, the binder is at least one of guar gum, sodium silicate, and bentonite.

[0014] The second aspect of this invention provides a method for preparing the red mud-based pretreatment agent for blast furnace gas described in the first aspect, comprising the following steps:

[0015] (1) Dry the Bayer red mud at 120~180℃ for 12~24h and grind it to a particle size of 50~100μm to obtain red mud powder;

[0016] (2) Mix the red mud powder, binder and alkaline regulator evenly to obtain a dry mixture;

[0017] (3) Add the active component solution to the dry mixture, mix and then extrude into strip-shaped precursor;

[0018] (4) Curing the strip-shaped precursor for 24-36 hours and then drying it at 105-150℃ for 4-8 hours to obtain the red mud-based pretreatment agent.

[0019] Furthermore, in step (2), the material mixing uniformity is ≤5%.

[0020] Furthermore, in step (3), the total amount of solution added is 30-40% of the dry mixture mass.

[0021] Furthermore, in step (3), the active component solution is an aqueous solution of the active component with a mass concentration of 10-15%.

[0022] Furthermore, in step (3), the diameter of the strip-shaped precursor is φ4~7mm.

[0023] The third aspect of the present invention provides the application of the red mud-based pretreatment agent for blast furnace gas described in the first aspect, wherein the pretreatment agent is used for blast furnace gas purification, and simultaneously achieves the removal of acidic gases and the conversion of organic sulfur.

[0024] Furthermore, the organic sulfur is COS.

[0025] The advantages of this invention compared to the prior art are as follows:

[0026] 1. Realize the high-value resource utilization of red mud: The red mud-based pretreatment agent for blast furnace gas described in this invention uses Bayer process red mud as the main raw material, which can consume a large amount of solid waste from the alumina industry, solve the environmental pollution problem of red mud storage, and turn waste into treasure;

[0027] 2. Significantly reduced cost: The cost of the red mud-based pretreatment agent for blast furnace gas described in this invention is only 50% of that of traditional aluminum-based dechlorination agents, and the protection effect can reach 86%~96%, which is economically outstanding;

[0028] 3. Dual-function integration: The red mud-based pretreatment agent for blast furnace gas described in this invention can simultaneously remove acidic gases and convert organic sulfur (COS) in blast furnace gas, replacing single-function dechlorination agents and extending the service life of hydrolysis catalysts in subsequent processes of fine desulfurization of blast furnace gas.

[0029] 4. Strong catalytic selectivity: In the red mud-based pretreatment agent for blast furnace gas described in this invention, potassium carbonate / potassium hydroxide is used as the active component, which has a high organic sulfur conversion efficiency. The effect is extremely poor after replacing calcium salt and sodium salt, proving that potassium salt is the core effective component.

[0030] 5. Simple preparation process and low energy consumption: The red mud-based pretreatment agent for blast furnace gas described in this invention only requires low-temperature drying and molding during preparation, without the need for high-temperature calcination. The energy consumption is reduced by more than 50% compared with the high-temperature calcination process, making it suitable for industrial production.

[0031] 6. Significant synergistic effect: In the red mud-based pretreatment agent for blast furnace gas described in this invention, the red mud matrix and potassium salt active components work synergistically, resulting in better organic sulfur conversion than a single carrier or a single red mud system, and higher catalytic efficiency. Detailed Implementation

[0032] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to exemplify and further explain and illustrate the content of the present invention, and are not intended to limit the present invention.

[0035] Example 1

[0036] This embodiment provides a red mud-based pretreatment agent for blast furnace gas, the raw materials of which include Bayer process red mud, guar gum, potassium carbonate, calcium hydroxide and water.

[0037] (1) Bayer red mud with a calcium oxide content of 10% and a sodium oxide content of 5% was dried at 120°C for 24 hours. The moisture content of the dried red mud was 6%. The dried red mud was then ground to obtain red mud powder with a particle size of 50~100μm.

[0038] (2) Dry mix red mud powder with calcium hydroxide and guar gum in a mass ratio of 87:10:3. Mix evenly to obtain a dry mixture. The order of feeding is red mud, calcium hydroxide and guar gum. The mixing uniformity is ≤5%.

[0039] (3) Prepare a potassium carbonate solution with a mass concentration of 15%. Add the potassium carbonate solution to the well-mixed dry mixture while stirring until the water content is 30%. Then extrude it into strips of φ4mm.

[0040] (4) The strip-shaped precursor was left to stand for 24 hours and then dried at 120°C for 8 hours to obtain red mud-based pretreatment agent product 1 with a moisture content of ≤5%.

[0041] Example 2

[0042] This embodiment provides a red mud-based pretreatment agent for blast furnace gas, the raw materials of which include Bayer process red mud, bentonite, potassium carbonate, calcium hydroxide and water.

[0043] (1) Bayer red mud with a calcium oxide content of 15% and a sodium oxide content of 5% was dried at 150°C for 24 hours. The moisture content of the dried red mud was 3%. The dried red mud was then ground to obtain red mud powder with a particle size of 50~100μm.

[0044] (2) Dry mix red mud powder with calcium hydroxide and bentonite in a mass ratio of 87:10:3. The order of feeding is red mud, calcium hydroxide and bentonite. The uniformity of mixing is ≤5%.

[0045] (3) Prepare a potassium carbonate solution with a mass concentration of 15%. Add the potassium carbonate solution to the well-mixed dry mixture while stirring until the water content is 30%. Then extrude it into strips of φ4mm.

[0046] (4) The strip-shaped precursor was left to stand for 24 hours and then dried at 120°C for 8 hours to obtain red mud-based pretreatment agent product 2 with a moisture content of ≤5%.

[0047] Example 3

[0048] This embodiment provides a red mud-based pretreatment agent for blast furnace gas, the raw materials of which include Bayer process red mud, bentonite, potassium hydroxide, calcium hydroxide and water.

[0049] (1) Bayer red mud with a calcium oxide content of 15% and a sodium oxide content of 5% was dried at 150°C for 24 hours. The moisture content of the dried red mud was 3%. The dried red mud was then ground to obtain red mud powder with a particle size of 50~100μm.

[0050] (2) Dry mix red mud powder with calcium hydroxide and bentonite in a mass ratio of 87:10:3. The order of feeding is red mud, calcium hydroxide and bentonite. The uniformity of mixing is ≤5%.

[0051] (3) Prepare a potassium hydroxide solution with a mass concentration of 15%. Add the potassium hydroxide solution to the well-mixed dry mixture while stirring until the water content is 30%. Then extrude it into a strip-shaped precursor with a diameter of φ4mm.

[0052] (4) The strip-shaped precursor was left to stand for 24 hours and then dried at 120°C for 8 hours to obtain red mud-based pretreatment agent product 3 with a moisture content of ≤5%.

[0053] Example 4

[0054] This embodiment provides a red mud-based pretreatment agent for blast furnace gas, the raw materials of which include Bayer process red mud, guar gum, potassium hydroxide, calcium hydroxide and water.

[0055] (1) Bayer red mud with a calcium oxide content of 10% and a sodium oxide content of 5% was dried at 120°C for 24 hours. The moisture content of the dried red mud was 6%. The dried red mud was then ground to obtain red mud powder with a particle size of 50~100μm.

[0056] (2) Dry mix red mud powder with calcium hydroxide and guar gum in a mass ratio of 87:10:3. The order of feeding is red mud, calcium hydroxide and guar gum, and the uniformity of mixing is ≤5%.

[0057] (3) Prepare a potassium hydroxide solution with a mass concentration of 15%. Add the potassium hydroxide solution to the well-mixed dry mixture while stirring until the water content is 30%. Then extrude it into a strip-shaped precursor with a diameter of φ4mm.

[0058] (4) The strip-shaped precursor was left to stand for 24 hours and then dried at 120°C for 8 hours to obtain red mud-based pretreatment agent product 4 with a moisture content of ≤5%.

[0059] Example 5

[0060] This embodiment provides a red mud-based pretreatment agent for blast furnace gas, the raw materials of which include Bayer process red mud, sodium silicate, potassium carbonate, calcium hydroxide and water.

[0061] (1) Bayer red mud with a calcium oxide content of 15% and a sodium oxide content of 5% was dried at 150°C for 24 hours. The moisture content of the dried red mud was 3%. The dried red mud was then ground to obtain red mud powder with a particle size of 50~100μm.

[0062] (2) Dry mix red mud powder with calcium hydroxide and sodium silicate in a mass ratio of 87:10:3. The order of feeding is red mud, calcium hydroxide and sodium silicate, and the uniformity of mixing is ≤5%.

[0063] (3) Prepare a potassium carbonate solution with a mass concentration of 10%. Add the potassium carbonate solution to the well-mixed dry mixture while stirring until the water content is 30%. Then extrude it into strips of φ4mm.

[0064] (4) The strip-shaped precursor was left to stand for 24 hours and then dried at 120°C for 8 hours to obtain red mud-based pretreatment agent product 5 with a moisture content of ≤5%.

[0065] Example 6

[0066] This embodiment provides a red mud-based pretreatment agent for blast furnace gas, the raw materials of which include Bayer process red mud, sodium silicate, potassium carbonate, calcium hydroxide and water.

[0067] (1) Bayer red mud with a calcium oxide content of 15% and a sodium oxide content of 5% was dried at 150°C for 24 hours. The moisture content of the dried red mud was 3%. The dried red mud was then ground to obtain red mud powder with a particle size of 50~100μm.

[0068] (2) Dry mix red mud powder with calcium hydroxide and sodium silicate in a mass ratio of 87:10:3. The order of feeding is red mud, calcium hydroxide and sodium silicate, and the uniformity of mixing is ≤5%.

[0069] (3) Prepare a potassium carbonate solution with a mass concentration of 10%. Add the potassium carbonate solution to the well-mixed dry mixture while stirring until the water content is 30%. Then extrude it into strips of φ4mm.

[0070] (4) The strip-shaped precursor was left to stand for 24 hours and then dried at 120°C for 8 hours to obtain red mud-based pretreatment agent product 6 with a moisture content of ≤5%.

[0071] Test Example 1

[0072] This test example evaluates the protective performance of different red mud-based pretreatment agents prepared in Examples 1-6, assesses their effectiveness in removing organic sulfur (COS), and tests their strength. Specific experimental procedure: A blast furnace gas line was drawn from the inlet of a blast furnace gas desulfurization unit in a steel plant and introduced into two parallel reaction units.

[0073] Test conditions for the reaction apparatus:

[0074]

[0075] The experimental group reaction apparatus loading was: 5L of red mud-based pretreatment agent (Examples 1-6) + 5L of hydrolysis catalyst;

[0076] The control group reaction apparatus was loaded with 5L of alumina-based dechlorinating agent and 5L of hydrolysis catalyst.

[0077] The experimental and control groups were filled with the same hydrolysis catalyst.

[0078] The hydrolysis catalyst used is a commercially available hydrolysis catalyst, and its specific parameters are shown in the table below:

[0079]

[0080] The control group used a commercially available alumina-based dechlorinating agent, with specific parameters shown in the table below:

[0081]

[0082] Six sets of experiments were conducted, and the results are shown in the table below.

[0083] Average conversion efficiency of organic sulfur in six experimental groups

[0084]

[0085] The results in the table above show that the protective effect of the red mud-based pretreatment agent described in Examples 1-6 is between 86% and 96% of that of the traditional alumina-based dechlorination agent (conversion efficiency of the experimental group / conversion efficiency of the control group). However, the price of the red mud-based pretreatment agent is only 50% of that of the alumina-based dechlorination agent, making it economical.

[0086] With the experimental conditions unchanged, and only red mud-based pretreatment agent added to the reaction apparatus, the organic sulfur removal rate was measured to be 26-37%, as detailed below:

[0087]

[0088] The results of this test case demonstrate that the protective effect of the red mud-based pretreatment agent of this invention reaches 87% to 96% of that of traditional alumina-based dechlorination agents, while the cost is only 50% of that of traditional alumina-based dechlorination agents, showing significant economic benefits.

[0089] The strengths of the different red mud-based pretreatment agent products prepared in Examples 1-6 are shown in the table below, and all of them meet the strength requirements of pretreatment agents (greater than 50 N / cm).

[0090]

[0091] Comparative Example 1

[0092] The only difference from Example 2 is that the active ingredient potassium carbonate is not added; the rest of the formulation, preparation process and testing conditions are the same.

[0093] The protective performance of the obtained red mud-based pretreatment agent was evaluated using the same method as in Test Example 1. The test results showed that the protective effect of the red mud-based pretreatment agent prepared in this comparative example was 86.55% of that of the control group, similar to the protective effect of Example 2. However, the evaluation showed that the removal efficiency of the red mud-based pretreatment agent in this comparative example for organic sulfur was only 1.37%, almost non-existent, indicating that potassium salt is a key component in the conversion of organic sulfur.

[0094] Comparative Example 2

[0095] The formula is the same as that in Example 2, except for the preparation process: the drying process in step (4) is replaced by calcination at 500°C for 5 hours after molding, and the other test conditions are the same.

[0096] The protective performance of the obtained red mud-based pretreatment agent was evaluated using the same method as in Test Example 1. The test results showed that the protective effect of the red mud-based pretreatment agent prepared in this comparative example was 88.37% of that of the control group, similar to the protective effect of Example 2. Meanwhile, the removal efficiency of the red mud-based pretreatment agent in this comparative example for organic sulfur was measured to be 32.35%, and the organic sulfur conversion efficiency showed no significant change compared to Example 2. However, the energy consumption increased significantly, exceeding 50% of the previous level; indicating that the high-temperature roasting efficiency was not improved.

[0097] Comparative Example 3

[0098] The only difference from Example 2 is that calcium salt is used instead of potassium salt, and potassium carbonate is replaced with equal masses of calcium carbonate and sodium carbonate, respectively. The rest of the process is the same.

[0099] The organic sulfur conversion rate of the obtained red mud-based pretreatment agent products was determined using the same method as in Test Example 1. The results showed that the organic sulfur conversion rate of the calcium carbonate group was 1.23%, and that of the sodium carbonate group was 2.35%, demonstrating that the catalytic effect of potassium salts is far superior to that of other alkali metal / alkaline earth metal salts.

[0100] Finally, it should be noted that the above description is only used to illustrate the technical solutions of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention.

Claims

1. A red mud-based pretreatment agent for blast furnace gas, characterized in that, The pretreatment agent comprises the following components by mass parts: 80-90 parts red mud, 0.1-3 parts binder, 3-5 parts active ingredient, 5-10 parts alkaline regulator, and 3-5 parts water; The red mud is Bayer process red mud, with a calcium oxide content of 10%~15% and a sodium oxide content of 5%~10%. The active component is one of potassium carbonate and potassium hydroxide.

2. The red mud-based pretreatment agent for blast furnace gas according to claim 1, characterized in that, The alkalinity regulator is at least one of calcium hydroxide and sodium hydroxide.

3. The red mud-based pretreatment agent for blast furnace gas according to claim 1, characterized in that, The binder is at least one of guar gum, sodium silicate, and bentonite.

4. A method for preparing a red mud-based pretreatment agent for blast furnace gas as described in any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: (1) Dry the Bayer red mud at 120~180℃ for 12~24h and grind it to a particle size of 50~100μm to obtain red mud powder; (2) Mix the red mud powder, binder and alkaline regulator evenly to obtain a dry mixture; (3) Add the active component solution to the dry mixture, mix and then extrude into strip-shaped precursor; (4) Curing the strip-shaped precursor for 24-36 hours and then drying it at 105-150℃ for 4-8 hours to obtain the red mud-based pretreatment agent.

5. The preparation method according to claim 4, characterized in that, In step (2), the material mixing uniformity is ≤5%.

6. The preparation method according to claim 4, characterized in that, In step (3), the total amount of solution added is 30-40% of the dry mixture mass.

7. The preparation method according to claim 4, characterized in that, In step (3), the active component solution is an aqueous solution of the active component with a mass concentration of 10-15%.

8. The preparation method according to claim 4, characterized in that, In step (3), the diameter of the strip-shaped precursor is φ4~7mm.

9. The application of the red mud-based pretreatment agent for blast furnace gas according to any one of claims 1 to 3, characterized in that, It is used for blast furnace gas purification, and simultaneously removes acidic gases and converts organic sulfur.

10. The application according to claim 9, characterized in that, The organic sulfur is COS.

Images