Method and device for treating photovoltaic acid mist waste gas by using red mud adsorbent

Abstract

The invention discloses a method and a device for treating photovoltaic acid mist waste gas by using a red mud adsorbent, and the method comprises the following steps: conveying the photovoltaic acid mist waste gas into an absorption device filled with the red mud adsorbent for treatment, then carrying out dust removal treatment, and then discharging the photovoltaic acid mist waste gas; the red mud adsorbent is prepared by the following steps: S1, pretreating red mud; and S2, uniformly mixing the pretreated red mud with a binder, a pore forming agent and water, carrying out extrusion molding, drying, roasting and cooling to obtain the red mud adsorbent. Red mud is solid waste generated in the aluminum smelting industry, has a rich pore structure and a large specific surface area and has good adsorption capacity on acid mist waste gas, the red mud is used as an adsorbent for treating the acid mist waste gas, and resource utilization of the waste is achieved; compared with wet treatment, the method does not need a large amount of chemical reagents and energy consumption, so that the pollution of the red mud to the environment is reduced, and the treatment cost of the acid mist waste gas is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a method and a device for treating photovoltaic acid mist waste gas by using red mud adsorbent. Background Art

[0002] Acid mist waste gas containing corrosive gases such as fluoride, chloride, and sulfide will be generated during the manufacturing process of photovoltaic cells. These acid mist waste gases will not only cause corrosion damage to equipment and pipelines, but also cause serious harm to the environment and human health. In 2022, the global photovoltaic cell production capacity was approximately 450GW, and it is expected to exceed 700GW in 2025. About 0.5 tons of acid mist waste gas needs to be treated during the production process of each megawatt of photovoltaic cells, which means that in 2025, the global photovoltaic cell industry will have more than 350,000 tons of acid mist waste gas that need to be treated. Therefore, the effective treatment of acid mist waste gas on the photovoltaic cell production line is of great significance to protecting the environment, reducing operating costs, and ensuring worker safety. For HF and NO emitted from the silicon wafer cleaning, diffusion, and secondary cleaning processes x , HCl, Cl 2 Acidic waste gas such as chlorine is mainly absorbed by alkaline solution spray washing and purification at home and abroad. The advantages of wet washing are high treatment efficiency, low investment cost, and simple operation. However, wet washing requires higher energy consumption when treating high-concentration waste gas. In order to avoid secondary pollution to the environment, the wastewater generated needs to be properly treated, which increases the difficulty and cost of wastewater treatment.

[0003] my country is the country with the largest alumina production in the world. Red mud is an industrial solid waste produced in the process of smelting alumina. According to statistics, on average, about 1 to 1.4 tons of red mud will be produced for every ton of alumina produced. The main chemical components of red mud are Al 2 O 3 , Fe 2 O 3 、SiO 2 , CaO, Na 2 O, etc., fine particles, large specific surface area, generally 64.09 ~ 186.9m 2 / g. The strong alkalinity and heavy metal toxicity of red mud, as well as the trace radioactivity and harmful elements it contains, are important factors restricting the comprehensive utilization of red mud. The generation of red mud is an important issue in the production process of alumina, and its disposal also poses many environmental problems, especially when it is disposed on land or water. Therefore, it is of great significance to seek solutions for the efficient use of red mud as a secondary resource material. Red mud particles are porous and have a larger specific surface area than limestone powder, which is very beneficial to its adsorption capacity and interface bonding performance.

[0004] The dry method is used to treat the acid mist waste gas generated by the photovoltaic industry. The solid waste generated during the treatment process is relatively small and easy to dispose of later. Compared with the wet method, the dry filtration treatment does not produce wastewater discharge, which reduces the demand and cost of wastewater treatment and helps to reduce the impact on the environment. At present, there are mainly activated carbon, SDG and other adsorbents in China. The research on red mud adsorbents to treat photovoltaic acid mist waste gas is not perfect. The adsorption performance of red mud is affected by many factors such as its composition, structure, porosity, etc., which may lead to unstable adsorption efficiency.

[0005] Therefore, it is necessary to improve the existing technology to provide a reliable treatment solution for photovoltaic acid mist waste gas. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method and device for treating photovoltaic acid mist waste gas by using red mud adsorbent in view of the deficiencies in the above-mentioned prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: In a first aspect of the present invention, a method for treating photovoltaic acid mist waste gas using red mud adsorbent is provided, wherein the photovoltaic acid mist waste gas is transported to an absorption device filled with red mud adsorbent for treatment, and then discharged after dust removal;

[0008] The red mud adsorbent is prepared by the following method:

[0009] S1, red mud pretreatment;

[0010] S2, mixing the pretreated red mud with a binder, a pore-forming agent and water uniformly, extruding and then drying, roasting and cooling to obtain the red mud adsorbent.

[0011] Preferably, the red mud adsorbent is prepared by the following method:

[0012] S1. Red mud pretreatment:

[0013] Dry the fresh red mud at 90-120° C. for 12-48 hours, and then grind it to less than 40-60 meshes to obtain pretreated red mud;

[0014] S2. The pretreated red mud is mixed evenly with a binder, a pore-forming agent and water, extruded and dried at 90-120° C. for 4-16 h, then calcined at 600-800° C. for 1-4 h, and cooled to room temperature to obtain the red mud adsorbent.

[0015] Binders can increase the compressive strength and stability of red mud, and pore-forming agents can increase the pores inside and outside the adsorbent, improve the porosity, increase the specific surface area, and be more conducive to the absorption of acid mist waste gas.

[0016] Activated carbon is a carbon-based material with carbon as the main element. Due to its rich pore structure and surface functional groups, large specific surface area, stable properties, and ability to adsorb harmful substances in industrial flue gas, it is often used as a pore-forming agent to improve adsorption performance.

[0017] After calcination, the specific surface area and porosity of red mud become larger, and the pore size distribution range of red mud is wide, with large pores and medium pores in the particles, so the specific pore volume is also larger, which is more conducive to flue gas adsorption.

[0018] Preferably, the binder is one or more of fly ash, sodium silicate or bentonite, and the added amount of the binder is 15-30% of the mass of the pretreated red mud.

[0019] Preferably, the pore-forming agent is activated carbon, and the amount of the pore-forming agent added is 5-10% of the mass of the pretreated red mud.

[0020] Preferably, the raw material mixed with the red mud in step S2 also includes an active supplement, and the active supplement is at least one of magnesium nitrate and manganese nitrate.

[0021] Preferably, the amount of the active supplement added is 2-8% of the mass of the pretreated red mud.

[0022] Preferably, the active supplement is a mixture of magnesium nitrate and manganese nitrate, and the mass ratio of magnesium nitrate to manganese nitrate is 1:2.

[0023] After calcination, magnesium nitrate and manganese nitrate form magnesium oxide and manganese oxide with porous structures, which can improve the porosity of the red mud adsorbent, thereby enhancing the physical adsorption performance; on the other hand, magnesium oxide and manganese oxide can effectively increase the number of alkaline active sites in the red mud adsorbent, thereby improving its chemical removal ability for acidic waste gas. The combination of magnesium oxide and manganese oxide can play a synergistic enhancement effect in removing acidic waste gas.

[0024] Preferably, the amount of water added in step S2 is 10-40% of the mass of the pretreated red mud.

[0025] Preferably, the method comprises the following steps:

[0026] The photovoltaic acid mist waste gas is transported to a dry absorption tower filled with red mud adsorbent. The waste gas treated by the dry absorption tower is then transported to a dust collector for dust removal. The waste gas after dust removal is drawn out by a fan and discharged from an exhaust pipe.

[0027] The second aspect of the present invention provides a device for treating photovoltaic acid mist waste gas using red mud adsorbent, the device comprising: a dry absorption tower, a dust collector connected to the dry absorption tower, an exhaust pipe connected to the dust collector through an exhaust pipeline, and a fan arranged on the exhaust pipeline, the dry absorption tower is filled with the above red mud adsorbent.

[0028] The beneficial effects of the present invention are:

[0029] The present invention provides a method and device for treating photovoltaic acid mist waste gas by using red mud adsorbent. Red mud is solid waste generated in the aluminum smelting industry, has rich pore structure and large specific surface area, and has good adsorption capacity for acid mist waste gas. The present invention uses red mud as an adsorbent to treat acid mist waste gas, thereby realizing resource utilization of waste. Compared with wet treatment, the present invention does not require a large amount of chemical reagents and energy consumption, which not only reduces the pollution of red mud to the environment, but also reduces the treatment cost of acid mist waste gas.

[0030] In some preferred embodiments of the present invention, magnesium nitrate and manganese nitrate are added as active supplements to the raw materials for preparing the red mud adsorbent. After calcination, magnesium nitrate and manganese nitrate form magnesium oxide and manganese oxide with a porous structure, which can increase the porosity of the red mud adsorbent on the one hand, thereby enhancing the physical adsorption performance; on the other hand, magnesium oxide and manganese oxide can effectively increase the number of alkaline active sites in the red mud adsorbent, thereby improving its chemical removal ability for acidic waste gas; and the combination of magnesium oxide and manganese oxide can achieve a synergistic enhancement effect in removing acidic waste gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of a device for treating photovoltaic acid mist waste gas using red mud adsorbent according to the present invention;

[0032] Figure 2 The present invention is a flow chart of a method for treating photovoltaic acid mist waste gas using red mud adsorbent.

[0033] Description of reference numerals:

[0034] 1—dry absorption tower; 2—bag dust collector; 3—exhaust pipe; 4—fan; 5—exhaust pipe; 11—red mud adsorbent. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0036] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0037] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0038] The red mud in the following examples has the same source, which is Bayer red mud from an alumina plant. The elements in the red mud are expressed in the form of oxides. The main components are shown in Table 1 below. The specific surface area of ​​the sample measured by BET analysis instrument is 73.415 m 2 / g, with a large specific surface area and good adsorption performance. 2 O 3 The composition proportion is relatively large, accounting for about 24.92%, followed by CaO and Al 2 O 3 They are 20.12% and 19.20% respectively. These components are beneficial to the absorption of acidic gases by red mud.

[0039] Table 1 Main chemical components of red mud

[0040] Components <![CDATA[Fe 2 THE 3 ]]> CaO <![CDATA[Al 2 THE 3 ]]> <![CDATA[SiO 2 ]]> <![CDATA[TiO 2 ]]> <![CDATA[Na 2 The]]> <![CDATA[K 2 The]]> MgO content(%) 24.92 20.12 19.20 7.39 6.52 3.23 0.67 0.72

[0041] Example 1

[0042] A device for treating photovoltaic acid mist waste gas using red mud adsorbent, referring to Figure 1 The device comprises: a dry absorption tower 1, a bag dust collector 2 connected to the dry absorption tower 1, an exhaust pipe 5 connected to the bag dust collector 2 through an exhaust pipe 3, and a fan 4 arranged on the exhaust pipe 3. The dry absorption tower 1 is filled with a red mud adsorbent 11. In this embodiment, the exhaust pipe is 25m high and Φ2m in diameter.

[0043] This embodiment also provides a method for treating photovoltaic acid mist waste gas using red mud adsorbent, which uses the above device to treat photovoltaic acid mist waste gas, referring to Figure 2 The specific steps are: 2 The photovoltaic acid mist waste gas with the same composition is transported to the dry absorption tower filled with red mud adsorbent. The waste gas treated by the dry absorption tower is then transported to the dust collector for dust removal. The waste gas after dust removal is drawn out by the fan and discharged from the exhaust pipe. The concentration of pollutants such as hydrochloric acid mist (in terms of hydrogen chloride), hydrofluoric acid mist (in terms of fluoride), chlorine, and nitrogen oxides at the outlet of the exhaust pipe is measured in real time using a flue gas analyzer.

[0044] In this embodiment, the red mud adsorbent is prepared by the following method:

[0045] S1. Red mud pretreatment:

[0046] After removing the large impurities in the fresh red mud, drying it at 105°C for 24 hours, and then grinding it to less than 40-60 meshes to obtain pretreated red mud;

[0047] S2. The pretreated red mud is mixed with fly ash as a binder, activated carbon as a pore-forming agent, and water until the mixture is slightly sticky and moist muddy. The amount of fly ash added is 15% of the mass of the pretreated red mud, the amount of activated carbon added is 5% of the mass of the pretreated red mud, and the amount of water added is 20% of the mass of the pretreated red mud (all on a dry basis);

[0048] The mixture was pressed into a cylindrical adsorbent with a diameter of Φ5 mm and a length of 3-5 cm in a plodder, and then dried in an oven at 105°C for 8 h, and then calcined at 600°C for 2 h and cooled to room temperature to obtain a red mud adsorbent.

[0049] Example 2

[0050] The difference between this example and Example 1 is that:

[0051] In this embodiment, the red mud adsorbent is prepared by the following method:

[0052] S1. Red mud pretreatment:

[0053] After removing the large impurities in the fresh red mud, drying it at 105°C for 24 hours, and then grinding it to less than 40-60 meshes to obtain pretreated red mud;

[0054] S2. The pretreated red mud is mixed with a binder, sodium silicate, a pore-forming agent, activated carbon, and water until the mixture is slightly sticky and moist muddy, wherein the amount of sodium silicate added is 20% of the mass of the pretreated red mud, the amount of activated carbon added is 8% of the mass of the pretreated red mud, and the amount of water added is 20% of the mass of the pretreated red mud (all on a dry basis);

[0055] The mixture was pressed into a cylindrical adsorbent with a diameter of Φ5 mm and a length of 3-5 cm in a plodder, and then dried in an oven at 105°C for 8 h, and then calcined at 700°C for 2 h and cooled to room temperature to obtain a red mud adsorbent.

[0056] Example 3

[0057] The difference between this example and Example 1 is that:

[0058] In this embodiment, the red mud adsorbent is prepared by the following method:

[0059] S1. Red mud pretreatment:

[0060] After removing the large impurities in the fresh red mud, drying it at 105°C for 24 hours, and then grinding it to less than 40-60 meshes to obtain pretreated red mud;

[0061] S2, the pretreated red mud and the binder bentonite, the pore-forming agent activated carbon, and water are mixed uniformly until the mixture is slightly sticky and moist mud, the amount of bentonite added is 30% of the mass of the pretreated red mud, the amount of activated carbon added is 10% of the mass of the pretreated red mud, and the amount of water added is 20% of the mass of the pretreated red mud (all on a dry basis);

[0062] The mixture was pressed into a cylindrical adsorbent with a diameter of Φ5 mm and a length of 3-5 cm in a plodder, and then dried in an oven at 105°C for 8 h, and then calcined at 800°C for 2 h and cooled to room temperature to obtain a red mud adsorbent.

[0063] Example 4

[0064] The difference between this example and Example 1 is that:

[0065] In this embodiment, the red mud adsorbent is prepared by the following method:

[0066] S1. Red mud pretreatment:

[0067] After removing the large impurities in the fresh red mud, drying it at 105°C for 24 hours, and then grinding it to less than 40-60 meshes to obtain pretreated red mud;

[0068] S2. The pretreated red mud is mixed evenly with a binder, sodium silicate, a pore-forming agent, activated carbon, an active supplement, magnesium nitrate, and water until the mixture is slightly sticky and moist muddy, wherein the amount of sodium silicate added is 20% of the mass of the pretreated red mud, the amount of activated carbon added is 8% of the mass of the pretreated red mud, the amount of magnesium nitrate added is 6% of the mass of the pretreated red mud, and the amount of water added is 20% of the mass of the pretreated red mud (all on a dry basis);

[0069] The mixture was pressed into a cylindrical adsorbent with a diameter of Φ5 mm and a length of 3-5 cm in a plodder, and then dried in an oven at 105°C for 8 h, and then calcined at 700°C for 2 h and cooled to room temperature to obtain a red mud adsorbent.

[0070] Example 5

[0071] The difference between this example and Example 1 is that:

[0072] In this embodiment, the red mud adsorbent is prepared by the following method:

[0073] S1. Red mud pretreatment:

[0074] After removing the large impurities in the fresh red mud, drying it at 105°C for 24 hours, and then grinding it to less than 40-60 meshes to obtain pretreated red mud;

[0075] S2. The pretreated red mud is mixed with a binder, sodium silicate, a pore-forming agent, activated carbon, an active supplement, manganese nitrate, and water until the mixture is slightly sticky and moist muddy, wherein the amount of sodium silicate added is 20% of the mass of the pretreated red mud, the amount of activated carbon added is 8% of the mass of the pretreated red mud, the amount of manganese nitrate added is 6% of the mass of the pretreated red mud, and the amount of water added is 20% of the mass of the pretreated red mud (all on a dry basis);

[0076] The mixture was pressed into a cylindrical adsorbent with a diameter of Φ5 mm and a length of 3-5 cm in a plodder, and then dried in an oven at 105°C for 8 h, and then calcined at 700°C for 2 h and cooled to room temperature to obtain a red mud adsorbent.

[0077] Example 6

[0078] The difference between this example and Example 1 is that:

[0079] In this embodiment, the red mud adsorbent is prepared by the following method:

[0080] S1. Red mud pretreatment:

[0081] After removing the large impurities in the fresh red mud, drying it at 105°C for 24 hours, and then grinding it to less than 40-60 meshes to obtain pretreated red mud;

[0082] S2. The pretreated red mud is mixed evenly with a binder of sodium silicate, a pore-forming agent of activated carbon, an active supplement (a mixture of magnesium nitrate and manganese nitrate in a mass ratio of 1:2), and water until the mixture is slightly sticky and moist muddy, wherein the amount of sodium silicate added is 20% of the mass of the pretreated red mud, the amount of activated carbon added is 8% of the mass of the pretreated red mud, the amount of active supplement added is 6% of the mass of the pretreated red mud, and the amount of water added is 20% of the mass of the pretreated red mud (all on a dry basis);

[0083] The mixture was pressed into a cylindrical adsorbent with a diameter of Φ5 mm and a length of 3-5 cm in a plodder, and then dried in an oven at 105°C for 8 h, and then calcined at 700°C for 2 h and cooled to room temperature to obtain a red mud adsorbent.

[0084] The method of Examples 1-6 was used to treat the same source of HF, HCl, Cl 2 The photovoltaic acid mist waste gas with equal components was treated, and the concentration of each acid waste gas at the exhaust pipe outlet was measured by an online flue gas measuring instrument, and the treatment efficiency was calculated. The test results are shown in Table 2 below.

[0085] Table 2

[0086]

[0087]

[0088] From the test results in Table 1, it can be seen that the process of the present invention has good performance on HF, HCl, Cl 2 The waste gases have a higher removal rate, and the addition of active supplements can effectively improve the removal efficiency of the waste gases, and when magnesium nitrate and manganese nitrate are used in combination, the relatively highest waste gas treatment efficiency can be achieved.

[0089] As described above, the present invention provides a method and device for treating photovoltaic acid mist waste gas using red mud adsorbent. Red mud is a solid waste generated in the aluminum smelting industry, has a rich pore structure and a large specific surface area, and has a good adsorption capacity for acid mist waste gas. The present invention uses red mud as an adsorbent to treat acid mist waste gas, realizing the resource utilization of waste; compared with wet treatment, the present invention does not require a large amount of chemical reagents and energy consumption, which not only reduces the pollution of red mud to the environment, but also reduces the treatment cost of acid mist waste gas. At the same time, in the embodiment of the present invention, magnesium nitrate and manganese nitrate are added as active supplements to the raw materials for preparing the red mud adsorbent. Magnesium nitrate and manganese nitrate form magnesium oxide and manganese oxide with a porous structure after calcination, which can improve the porosity of the red mud adsorbent on the one hand, thereby enhancing the physical adsorption performance; on the other hand, magnesium oxide and manganese oxide can effectively increase the number of alkaline active sites in the red mud adsorbent, thereby improving its chemical removal ability for acidic waste gas; and the combination of magnesium oxide and manganese oxide can play a synergistic enhancement effect in removing acidic waste gas.

[0090] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for treating photovoltaic acid mist waste gas using red mud adsorbent, characterized in that: The method comprises: transporting the photovoltaic acid mist waste gas to an absorption device filled with red mud adsorbent for treatment, and then performing dust removal treatment before discharge; The red mud adsorbent is prepared by the following method: S1, red mud pretreatment; S2, mixing the pretreated red mud with a binder, a pore-forming agent and water uniformly, extruding and molding, drying, roasting and cooling to obtain the red mud adsorbent.

2. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 1, characterized in that: The red mud adsorbent is prepared by the following method: S1. Red mud pretreatment: Dry the fresh red mud at 90-120° C. for 12-48 hours, and then grind it to less than 40-60 meshes to obtain pretreated red mud; S2. The pretreated red mud is mixed evenly with a binder, a pore-forming agent and water, extruded and dried at 90-120° C. for 4-16 h, then calcined at 600-800° C. for 1-4 h, and cooled to room temperature to obtain the red mud adsorbent.

3. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 1, characterized in that: The binder is one or more of fly ash, sodium silicate or bentonite, and the added amount of the binder is 15-30% of the mass of the pretreated red mud.

4. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 1, characterized in that: The pore-forming agent is activated carbon, and the added amount of the pore-forming agent is 5-10% of the mass of the pretreated red mud.

5. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 1, characterized in that: The raw material mixed with the red mud in step S2 also includes an active supplement, and the active supplement is at least one of magnesium nitrate and manganese nitrate.

6. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 5, characterized in that: The amount of the active supplement added is 2-8% of the mass of the pretreated red mud.

7. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 6, characterized in that: The active supplement is a mixture of magnesium nitrate and manganese nitrate, and the mass ratio of magnesium nitrate to manganese nitrate is 1:

2.

8. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 1, characterized in that: The amount of water added in step S2 is 10-40% of the mass of the pretreated red mud.

9. The method for treating photovoltaic acid mist waste gas using red mud adsorbent according to claim 1, characterized in that: The method comprises the following steps: The photovoltaic acid mist waste gas is transported to a dry absorption tower filled with red mud adsorbent. The waste gas treated by the dry absorption tower is then transported to a dust collector for dust removal. The waste gas after dust removal is drawn out by a fan and discharged from an exhaust pipe.

10. A device for treating photovoltaic acid mist waste gas using red mud adsorbent, characterized in that: The device comprises: a dry absorption tower, a dust collector connected to the dry absorption tower, an exhaust pipe connected to the dust collector through an exhaust pipeline, and a fan arranged on the exhaust pipeline. The dry absorption tower is filled with a red mud adsorbent as claimed in any one of claims 1 to 9.

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