Efficient calcium-based flue gas desulfurizer and preparation method thereof

Abstract

The invention provides an efficient calcium-based flue gas desulfurizer and a preparation method thereof. Based on the total mass of the desulfurizing agent, the desulfurizing agent comprises the following components in percentage by mass: 60-80% of calcium hydroxide; 0-5% of alumina; 2-8% of titanium dioxide; 3-10% of clay and 3-20% of a metal compound auxiliary agent; 3-15% of a binder; the clay is one or more selected from the group consisting of montmorillonite powder, attapulgite and kaolin, and the other auxiliary agents are one or more selected from the group consisting of bentonite powder, attapulgite and kaolin; the metal compound additive is selected from one or more of ferric sulfate, cerium oxide, magnesium oxide, manganese sulfate and copper oxide; the binder is selected from one or more of attapulgite, kaolin, pseudo-boehmite, sodium carboxymethyl cellulose and cement. The desulfurizer disclosed by the invention has the characteristics of high specific surface area, large pore volume, developed pore structure, high desulfurization performance, long service cycle and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial flue gas purification, and particularly relates to a high-efficiency calcium-based flue gas desulfurizer and a preparation method thereof. The desulfurizer is applicable to dry flue gas desulfurization and can be used for flue gas treatment in industries such as iron and steel and coking. Background Art

[0002] During the rapid development of the industrial society, humans have consumed a large amount of fossil fuels such as coal and oil. Among them, industries such as iron and steel, coking, building materials, petrochemical, and power emit harmful polluting gases such as SOx and NOx into the atmosphere, which endanger the balance of the ecosystem and become an important factor restricting the sustainable development of the economy and society.

[0004] The composition of coke oven flue gas is complex, and the SO2 concentration is high (usually 100 - 1000 mg / m 3 ). Although traditional wet flue gas desulfurization (such as limestone-gypsum method) is widely used in industry and has high desulfurization efficiency, there are problems in the operation process such as serious corrosion of desulfurization equipment by acidic substances (such as SO3 2- , Cl - ), large amount of desulfurization waste liquid to be treated and containing heavy metals, Cl - and other pollutants, high cost of wastewater treatment, and high operation cost and energy consumption.

[0005] Common dry flue gas desulfurization methods mainly include: SDS sodium-based dry desulfurization and calcium-based dry desulfurization. Among them, SDS sodium-based dry desulfurization uses baking soda as a desulfurizer to react with acidic gases such as SO2, SO3, and HCl in the flue gas to generate sodium salts such as sodium sulfate, thereby achieving the desulfurization effect. Although this process has advantages such as high desulfurization efficiency and low wastewater production, the desulfurization by-products sodium sulfate or sodium sulfite of baking soda are hazardous wastes, which bring additional treatment costs for further treatment. And when SDS sodium-based dry desulfurization removes SO2 in the flue gas, it generates CO with twice the molar number of SO2 2。

[0006] Calcium-based dry desulfurization uses slaked lime Ca(OH)2 as an absorbent to achieve the purpose of flue gas purification by chemically reacting with SO2. The by-products after desulfurization are calcium sulfate and calcium sulfite, which belong to general solid wastes and can be used as roadbed materials for road construction and cement building material additives, with wide uses and easy to dispose of. Since 2021, high specific surface area calcium hydroxide desulfurization has gradually replaced baking soda and has become an inevitable trend for future dry desulfurization.

[0007] The existing calcium hydroxide desulfurizer has the following problems in the production preparation and industrial use processes:

[0008] (1) The pore structure is generally dense, and CaSO3 or CaSO4 generated by the reaction of Ca(OH)2 and SO2 covers the surface of the particles, which hinders the unreacted desulfurizer inside from continuing to participate in the reaction, resulting in insufficient utilization of adsorbent calcium (the actual utilization rate is only 30% to 40%) and low desulfurizer performance;

[0009] (2) Existing calcium-based desulfurizers are mainly composed of calcium hydroxide and binders. Due to the single component, small specific surface area, few reactive center sites, and insufficient active oxygen formation, the sulfur dioxide solidification reaction ability is weak, the desulfurizer activity is poor, and it cannot meet the national environmental protection emission standards.

[0010] (3) The existing calcium-based desulfurizer has low mechanical strength after molding. In industrial production applications, it is easy to cause the desulfurizer to powder, affecting particulate matter emissions that do not meet standards.

[0011] Therefore, in order to ensure that SO2 emissions meet standards, reduce the operating burden of enterprises, and meet the actual needs of industrial production, it is urgent to develop a low-cost, high-specific surface area, and high-performance desulfurizer. Summary of the invention

[0012] The purpose of the present invention is to solve the problem that the coke oven flue gas has complex components and high SO2 concentration (usually 100-1000 mg / m 3 ), the existing desulfurizers cannot effectively meet the actual application needs of industry. In order to overcome the technical deficiencies of the existing calcium hydroxide desulfurizers, the purpose of the present invention is to provide a high-efficiency calcium-based flue gas desulfurizer and a preparation method thereof. The calcium hydroxide desulfurizer of the present invention has the characteristics of high specific surface area and large pore volume, developed pore structure, high desulfurization performance, long service life, etc.

[0013] In order to achieve the above-mentioned object of the invention, the present invention is implemented by adopting the following technical solutions:

[0014] The present invention (1) forms a pore structure inside the desulfurizer by adding a dispersant, promotes the diffusion of the reaction gas in the pores, and improves the calcium utilization rate of the desulfurizer; (2) increases the reaction center sites by adding a metal active auxiliary agent, provides active oxygen to participate in the SO2 solidification reaction, improves the surface properties of calcium hydroxide, and can improve the adsorption capacity and sustained reaction capacity of SO2 gas; (3) improves the mechanical strength of the desulfurizer, and in actual industrial production applications, does not cause excessive particle emissions due to the powderization of the desulfurizer.

[0015] According to one aspect of the present invention, a calcium-based flue gas desulfurizer is provided. Based on the total mass of the desulfurizer, the calcium-based flue gas desulfurizer comprises the following components in mass fractions, or is composed of the following components in mass fractions: 60-80% calcium hydroxide; 0-5% aluminum oxide; 2-8% titanium dioxide; 3-10% clay; 3-20% metal compound additive; 3-15% binder; and 0-4% other additives.

[0016] Among them,

[0017] the clay is one or more selected from montmorillonite powder, attapulgite, and kaolin;

[0018] the metal compound auxiliary is one or more selected from ferric sulfate, cerium oxide, magnesium oxide, manganese sulfate, and copper oxide;

[0019] the binder is one or more selected from attapulgite, kaolin, pseudoboehmite, sodium carboxymethyl cellulose, and cement.

[0020] According to the present invention, in some embodiments, based on the total mass of the desulfurizer, the calcium-based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60-80%; alumina 0-5%; titanium dioxide 2-5%; clay 5-8%, metal compound auxiliary 3-20%; binder 3-15%; and other auxiliaries 0-4%.

[0021] According to the present invention, in some embodiments, based on the total mass of the desulfurizer, the calcium-based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60-70%; alumina 3-5%; titanium dioxide 2-5%; clay 5-8%, metal compound auxiliary 3-20%; binder 3-15%; and other auxiliaries 0-4%.

[0022] According to the present invention, in some embodiments, based on the total mass of the desulfurizer, the calcium-based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60-70%, montmorillonite powder 5-8%, alumina 3-5%, titanium dioxide 2-5%, magnesium oxide 2-4%, cerium oxide 1-2%, copper oxide 2-5%, sodium carboxymethyl cellulose 4-6%, cement 3-5%.

[0023] According to the present invention, in some embodiments, based on the total mass of the desulfurizer, the calcium-based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60-70%, attapulgite 5-8%, alumina 3-5%, titanium dioxide 2-5%, cerium oxide 1-2%, manganese sulfate 2-5%, ferric sulfate 2-5%, sodium carboxymethyl cellulose 4-6%, calcium sulfate 3-5%.

[0024] According to the present invention, in some embodiments, the BET specific surface area of the calcium-based flue gas desulfurizer is 18 m 2 / g or more, for example 18-25 m 2 / g; and / or the pore volume is 0.05 cm 3above / g, for example, 0.07 - 0.15 cm 3 / g; and / or the pore size is 10 - 30 nm.

[0025] According to the present invention, in some embodiments, the compressive strength of the calcium-based flue gas desulfurizer is 120 - 140 N / cm; and / or the sulfur capacity is 25 - 40 mg / g.

[0026] On the other hand, according to the present invention, a method for preparing the calcium-based flue gas desulfurizer is provided, comprising the following steps:

[0027] (1) Material mixing: fully stirring and mixing the raw material components evenly in a dry powder state;

[0028] (2) Mud preparation: adding water to the mixed material obtained in step (1), mixing to allow the materials to fully undergo a hydration reaction until the materials present loose state particles, obtaining plastic mud;

[0029] (3) Molding: feeding the plastic mud obtained in step (2) into an extrusion molding machine, first kneading the mud, for example, pre-extruding 2 - 3 times, and then performing molding, for example, extrusion molding, to obtain a desulfurizer green body;

[0030] (4) Drying and packaging: dehydrating and drying the desulfurizer green body obtained in step (3), cutting if necessary, and packaging to obtain the desulfurizer.

[0031] According to the method of the present invention, in some embodiments, in step (1) of material mixing,

[0032] adding the raw material components calcium hydroxide, alumina, titanium dioxide, clay, metal compound additives, and binder into the mixer in sequence, and fully stirring and mixing evenly in a dry powder state; or, mixing calcium hydroxide and clay in the mixer, and then adding alumina, titanium dioxide, metal compound additives, and binder in sequence, and fully stirring and mixing evenly in a dry powder state.

[0033] According to the method of the present invention, in some embodiments, in step (1), the mixing time of the materials is at least 30 min.

[0034] According to the method of the present invention, in some embodiments, in step (1), the particle size of each raw material component is 100 - 300 mesh.

[0035] According to the method of the present invention, in some embodiments, in step (2) of mud preparation, introducing the mixed material in step (1) into a mixer, and adding water at 70 - 80 °C in a kneading state, allowing the materials to fully undergo a hydration reaction until the materials present loose state particles, obtaining plastic mud.

[0036] According to the method of the present invention, in some embodiments, in step (2), the amount of water added is 20-30% of the mass of the material.

[0037] According to the method of the present invention, in some embodiments, in step (2), the stirring time of the material is at least 40 min.

[0038] According to the method of the present invention, in some embodiments, in the forming step (3), the plastic clay obtained in step (2) is fed into an extrusion molding machine. After pre-extruding the clay 2-3 times, then perform forming extrusion to obtain a strip-shaped desulfurizer blank.

[0039] According to the method of the present invention, in some embodiments, in step (3), the shape of the desulfurizer blank is cylindrical or four-leaf clover-shaped.

[0040] According to the method of the present invention, in some embodiments, in the drying and packaging step (4), the desulfurizer blank obtained in step (3) is dehydrated and dried, cut if necessary, and packaged to obtain the desulfurizer.

[0041] According to the method of the present invention, in some embodiments, in step (4), for the dehydration drying of the desulfurizer blank, it can be air-dried in a natural environment (15-40 °C) for 2-4 days, or dried in a hot air dryer at a temperature of 105-115 °C for 2-5 h.

[0042] According to the method of the present invention, in some embodiments, in step (4), the specifications of the desulfurizer are 6-9 mm in width and 15-25 mm in length, for example, a cylindrical or four-leaf clover-shaped desulfurizer with a diameter of 6-9 mm and a length of 15-25 mm.

[0043] According to the present invention, calcium hydroxide can be a commercially available product, such as industrial calcium hydroxide and slaked lime, or can also be prepared by conventional techniques in the art.

[0044] According to the present invention, other additives can be conventional additives in the art, such as molding aids (such as calcium sulfate added during extrusion molding), etc.

[0045] According to another aspect of the present invention, there is provided the use of the calcium-based flue gas desulfurizer described above, or the calcium-based flue gas desulfurizer prepared according to the above method, for desulfurizing coke oven flue gas.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) In the high-efficiency calcium-based flue gas desulfurizer and its preparation method of the present invention, alumina, as a solid material with a high degree of dispersion, promotes the formation of pore structures inside the desulfurizer by adding an alumina dispersant, enabling the desulfurizer to have a relatively high specific surface area, promoting the diffusion of reaction gases in the pores, contacting more active sites, and improving the adsorption performance and calcium utilization rate of the desulfurizer; at the same time, adding alumina increases the mechanical strength of the desulfurizer product.

[0048] (2) In the high-efficiency calcium-based flue gas desulfurizer and its preparation method of the present invention, by adding metal active additives such as ferric sulfate and magnesium oxide, the number of reactive active center sites is increased, and SO2 is efficiently catalytically oxidized to SO3 by providing active oxygen to complete the SO2 solidification reaction, thereby improving the surface characteristics of calcium hydroxide; at the same time, the metal oxides of ferric sulfate and magnesium oxide form a synergistic effect, further enhancing the adsorption capacity and impact resistance of SO2 gas, and improving the reaction performance of the calcium-based desulfurizer.

[0049] (3) In the high-efficiency calcium-based flue gas desulfurizer and its preparation method of the present invention, montmorillonite powder has a unique layered structure and ion exchange characteristics. By adding montmorillonite powder to the desulfurizer, its physical adsorption capacity is further regulated, and the ability of the desulfurizer to remove tar and dust in flue gas is enhanced. In addition, montmorillonite powder regulates the consistency and strength of the mud during the extrusion molding process, which is beneficial to the industrial extrusion of the desulfurizer.

[0050] (4) In the high-efficiency calcium-based flue gas desulfurizer and its preparation method of the present invention, the sulfur capacity of the calcium-based desulfurizer produced by this process formula is as high as more than 35%, and the compressive strength of the desulfurizer is as high as more than 125 N / cm. In industrial production applications, particulate matter over-standard emissions will not be caused by the powdering of the desulfurizer; at the same time, it has good impact resistance to high-concentration SO2, and the flue gas SO2 removal efficiency reaches more than 98%. This preparation process is simple, which is conducive to promoting enterprises to achieve "cost reduction and efficiency increase". Description of the Drawings

[0051] Figure 1 It is a scanning electron microscope image of the calcium-based desulfurizer product prepared in Example 1 of the present invention. Detailed Embodiments

[0052] To facilitate the understanding of the present invention, the present invention will be further described below in conjunction with embodiments and drawings. The following description is only for explaining the present invention and does not limit the protection scope of the present invention.

[0053] Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products. Among them, alumina is purchased from Gongyi Renyuan Water Treatment Materials Factory.

[0054] Example 1:

[0055] 1. Weigh 700 g of calcium hydroxide and mix it with 70 g of montmorillonite powder. Then, add 30 g of alumina, 40 g of titanium dioxide, 25 g of magnesium oxide, 10 g of cerium oxide, 30 g of copper oxide, 50 g of sodium carboxymethyl cellulose, and 45 g of cement into the mixer in sequence. Stir thoroughly for 50 minutes under dry powder state to mix evenly.

[0056] 2. Pour the above mixed materials into the blender, and add water at 70 - 80 °C accounting for 20 - 30% of the material mass until the materials present loose state particles, obtaining plastic clay.

[0057] 3. Then, send the obtained plastic clay into the extrusion molding machine and extrude it into a cylindrical shape with a diameter of 6 - 9 mm and a length of 15 - 25 mm or a four - leaf clover shape.

[0058] 4. After dehydrating and drying at 105 °C for 3 h, the calcium - based desulfurizer product is obtained.

[0059] Example 2:

[0060] 1. Weigh 760 g of calcium hydroxide and mix it with 50 g of montmorillonite powder. Then, add 35 g of manganese sulfate, 20 g of titanium dioxide, 40 g of magnesium oxide, 35 g of iron sulfate, and 60 g of pseudo - boehmite into the mixer in sequence. Stir thoroughly for 30 minutes under dry powder state to mix evenly.

[0061] 2. Pour the above mixed materials into the blender, and add water at 70 - 80 °C accounting for 20 - 30% of the material mass until the materials present loose state particles, obtaining plastic clay.

[0062] 3. Then, send the obtained plastic clay into the extrusion molding machine and extrude it into a cylindrical shape with a diameter of 6 - 9 mm and a length of 15 - 25 mm or a four - leaf clover shape.

[0063] 4. After dehydrating and drying at 100 °C for 4 h, the calcium - based desulfurizer product is obtained.

[0064] Example 3:

[0065] 1. Weigh 660 g of calcium hydroxide and mix it with 60 g of attapulgite. Then, add 40 g of alumina, 40 g of titanium dioxide, 40 g of manganese sulfate, 20 g of cerium oxide, 40 g of iron sulfate, 60 g of sodium carboxymethyl cellulose, and 40 g of calcium sulfate into the mixer in sequence. Stir thoroughly for 70 minutes under dry powder state to mix evenly.

[0066] 2. Pour the above mixed materials into the blender, and add water at 70 - 80 °C accounting for 20 - 30% of the material mass until the materials present loose state particles, obtaining plastic clay.

[0067] 3. Then, feed the obtained plasticizable mud into an extrusion molding machine and extrude it into a cylindrical or four-leaf clover shape with a diameter of 6 - 9 mm and a length of 15 - 25 mm.

[0068] 4. After dehydrating and drying at 110 °C for 2 h, the calcium-based desulfurizer product is obtained.

[0069] Example 4:

[0070] 1. Weigh 660 g of calcium hydroxide and mix it with 60 g of kaolin. Then, add 60 g of copper oxide, 30 g of titanium dioxide, 10 g of cerium oxide, 40 g of magnesium oxide, 50 g of manganese sulfate, 50 g of sodium carboxymethyl cellulose, and 40 g of pseudo-boehmite into the mixer in sequence. Stir well for 60 minutes in the dry powder state to mix evenly.

[0071] 2. Feed the above mixed materials into a blender and add water at 70 - 80 °C accounting for 20 - 30% of the material mass until the materials present loose state particles to obtain plasticizable mud.

[0072] 3. Then, feed the obtained plasticizable mud into an extrusion molding machine and extrude it into a cylindrical or four-leaf clover shape with a diameter of 6 - 9 mm and a length of 15 - 25 mm.

[0073] 4. After dehydrating and drying at 103 °C for 2.5 h, the calcium-based desulfurizer product is obtained.

[0074] Comparative Example 1:

[0075] 1. Weigh 625 g of calcium hydroxide and mix it with 100 g of attapulgite. Then, add 55 g of ferric sulfate, 40 g of manganese sulfate, 25 g of cerium oxide, 35 g of magnesium oxide, 60 g of sodium carboxymethyl cellulose, and 60 g of cement into the mixer in sequence. Stir well for 50 minutes in the dry powder state to mix evenly.

[0076] 2. Feed the above mixed materials into a blender and add water at 70 - 80 °C accounting for 20 - 30% of the material mass until the materials present loose state particles to obtain plasticizable mud.

[0077] 3. Then, feed the obtained plasticizable mud into an extrusion molding machine and extrude it into a cylindrical or four-leaf clover shape with a diameter of 6 - 9 mm and a length of 15 - 25 mm.

[0078] 4. After dehydrating and drying at 108 °C for 2.2 h, the calcium-based desulfurizer product is obtained.

[0079] Comparative Example 2:

[0080] 1. Weigh 700 g of calcium hydroxide and mix it with 80 g of montmorillonite powder. Then, add 60 g of alumina, 50 g of manganese sulfate, 70 g of kaolin, and 40 g of pseudo-boehmite into the mixer in sequence. Stir well for 50 minutes in the dry powder state to mix evenly.

[0081] 2. The above mixed materials are introduced into a mixer, and 70-80°C water accounting for 20-30% of the material mass is added until the material presents loose particles to obtain plastic mud;

[0082] 3. Then the obtained plastic mud is fed into an extruder and extruded into a cylindrical or four-leaf clover shape with a diameter of 6-9 mm and a length of 15-25 mm;

[0083] 4. After dehydration and drying at 110°C for 2.5 hours, the calcium-based desulfurizer product is obtained.

[0084] The ASAP 2460 physical adsorption analyzer produced by McMurritic (Shanghai) Instrument Co., Ltd. was used to measure the adsorption amount and adsorption isotherm of the adsorbent on the material surface, and the specific surface area S was calculated by the BET method (Brunauer-Emmett-Teller method) combined with the BJH method. BET (m 2 / g), pore volume V pore (cm 3 / g) and pore size D pore (nm), the results are shown in the following table:

[0085] Sample <![CDATA[S BET (m 2 / g)]]> <![CDATA[V pore (cm 3 / g)]]> <![CDATA[D pore (nm)]]> Example 1 21.88 0.12 22.70 Example 2 17.91 0.08 16.75 Example 3 19.37 0.07 13.57 Example 4 18.42 0.09 18.63 Comparative Example 1 15.17 0.04 10.48 Comparative Example 2 10.78 0.03 14.21

[0086] The compressive strength of the desulfurizers prepared in the examples and comparative examples was measured by applying pressure to the desulfurizer particles using an electronic universal testing machine.

[0087] The sulfur capacity of the desulfurizers prepared in the examples and comparative examples was determined by the method described in HG / T2513.

[0088] Table 1 shows the test data of the desulfurizers of Examples 1 to 4 and Comparative Examples 1 to 2.

[0089] Table 1 Desulfurization agent test data

[0090]

[0091] Performance evaluation experiment:

[0092] The present invention carries out performance evaluation experiments on a fixed bed device, and the experimental flue gas conditions are: SO2 concentration 300mg / m 3 Under the conditions of flue gas flow rate of 1000ml / min, reaction temperature of 260℃, oxygen content of 6%, and experimental space velocity of 50000h-1, the flue gas containing SO2 was treated. When the desulfurizer adsorption catalysis was carried out for 7h, the concentration of SO2 inlet and outlet gas in the flue gas was measured by Testo 350 analyzer, and the removal efficiency was calculated. The results are shown in Table 2.

[0093] Table 2 is the data table for detecting the SO2 removal efficiency of the desulfurizers prepared in Examples 1-4 and Comparative Examples 1-2.

[0094] Table 2 Performance evaluation data of the desulfurizer

[0095]

[0096] In summary, in Examples 1-4 of the present invention, components such as alumina, titanium dioxide, clay such as montmorillonite powder, metal compound additives, and binders effectively increase the pore structure of the desulfurizer, thereby improving the sulfur capacity and compressive strength of the desulfurizer; at the same time, the alkaline metal compound / oxide acts as an active additive, improving the surface activity of calcium hydroxide, enhancing the adsorption and catalytic oxidation of SO2 gas, showing a SO2 removal ability of more than 95%, having a high specific surface area and rich pore structure characteristics. The alkaline metal oxide acts as an active additive, providing active oxygen to participate in the sulfur dioxide solidification reaction, improving the surface characteristics of calcium hydroxide, and being able to improve the adsorption ability and continuous reaction ability of SO2 gas, with a desulfurization efficiency of more than 95%, proving the scientificity of the raw material combination of the high-efficiency calcium-based flue gas desulfurizer and its preparation method described in the present invention.

[0097] Obviously, the above examples are only for clear illustration and not for limiting the implementation mode. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation modes here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A calcium-based flue gas desulfurizer, wherein, Based on the total mass of the desulfurizer, it comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60 - 80%; alumina 0 - 5%; titanium dioxide 2 - 8%; clay 3 - 10%; metal compound additive 3 - 20%; binder 3 - 15%; and other additives 0 - 4%. Among them, the clay is one or more selected from montmorillonite powder, attapulgite, and kaolin; the metal compound additive is one or more selected from ferric sulfate, cerium oxide, magnesium oxide, manganese sulfate, and copper oxide; the binder is one or more selected from attapulgite, kaolin, pseudoboehmite, sodium carboxymethyl cellulose, and cement.

2. The calcium-based flue gas desulfurizer according to claim 1, wherein, Based on the total mass of the desulfurizer, the calcium - based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60 - 80%; alumina 0 - 5%; titanium dioxide 2 - 5%; clay 5 - 8%, metal compound additive 3 - 20%; binder 3 - 15%; and other additives 0 - 4%.

3. The calcium-based flue gas desulfurizer according to claim 1, wherein, Based on the total mass of the desulfurizer, the calcium - based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60 - 70%; alumina 3 - 5%; titanium dioxide 2 - 5%; clay 5 - 8%, metal compound additive 3 - 20%; binder 3 - 15%; and other additives 0 - 4%.

4. The calcium-based flue gas desulfurizer according to claim 1, wherein, The calcium - based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60 - 70%, montmorillonite powder 5 - 8%, alumina 3 - 5%, titanium dioxide 2 - 5%, magnesium oxide 2 - 4%, cerium oxide 1 - 2%, copper oxide 2 - 5%, sodium carboxymethyl cellulose 4 - 6%, cement 3 - 5%.

5. The calcium-based flue gas desulfurizer according to claim 1, wherein, Based on the total mass of the desulfurizer, the calcium - based flue gas desulfurizer comprises the following components by mass fraction, or consists of the following components by mass fraction: calcium hydroxide 60 - 70%, attapulgite 5 - 8%, alumina 3 - 5%, titanium dioxide 2 - 5%, cerium oxide 1 - 2%, manganese sulfate 2 - 5%, ferric sulfate 2 - 5%, sodium carboxymethyl cellulose 4 - 6%, calcium sulfate 1 - 4%.

6. The calcium-based flue gas desulfurizer according to any one of claims 1 to 5, wherein, The BET specific surface area of the calcium-based flue gas desulfurizer is above 18 m 2 / g, for example, 18 - 25 m 2 / g; and / or the pore volume is above 0.05 cm 3 / g, for example, 0.07 - 0.15 cm 3 / g; and / or the pore diameter is 10 - 30 nm; and / or The compressive strength of the calcium - based flue gas desulfurizer is 120 - 140 N / cm; and / or the sulfur capacity is 25 - 40 mg / g.

7. A method for preparing the calcium - based flue gas desulfurizer according to any one of claims 1 to 6, comprising the following steps: (1) Material mixing: fully stirring and mixing the raw material components evenly in a dry - powder state; (2) Mud preparation: adding water to the mixed material obtained in step (1), mixing to allow the materials to fully undergo a hydration reaction until the materials present loose - state particles, obtaining plastic mud; (3) Molding: feeding the plastic mud obtained in step (2) into an extrusion molding machine, first kneading the mud, for example, pre - extruding 2 - 3 times, and then performing molding, for example, extrusion molding, to obtain a desulfurizer blank; (4) Drying and packaging: dehydrating and drying the desulfurizer blank obtained in step (3), cutting if necessary, and packaging to obtain the calcium - based flue gas desulfurizer.

8. According to the method of claim 7, wherein, In step (1), calcium hydroxide, alumina, titanium dioxide, clay, metal compound additives, and binder, as the raw material components, are successively added into a mixer and thoroughly stirred and mixed evenly in a dry powder state; alternatively, calcium hydroxide and clay are mixed in a mixer, and then alumina, titanium dioxide, metal compound additives, and binder are successively added, and thoroughly stirred and mixed evenly in a dry powder state; and / or In step (2), the mixed material in step (1) is introduced into a stirrer, and water at 70 - 80 °C is added in a kneading state to enable the materials to fully undergo a hydration reaction until the materials present loose state particles, obtaining plastic clay; and / or In step (3), the plastic clay obtained in step (2) is fed into an extrusion molding machine. First, the clay is pre-extruded 2 - 3 times, and then extrusion molding is carried out to obtain a strip-shaped desulfurizer blank; and / or In step (4), the desulfurizer blank obtained in step (3) is dehydrated and dried, and cut and packaged if necessary to obtain a calcium-based flue gas desulfurizer.

9. The method according to claim 7 or 8, wherein in step (1), the mixing time of the materials is at least 30 min; and / or in step (1), the particle size of each raw material component is 100 - 300 mesh; and / or in step (2), the stirring time of the materials in the stirrer is at least 40 min; and / or in step (3), the shape of the desulfurizer blank is cylindrical or four-leaf clover-shaped; and / or in step (4), the dehydration and drying of the desulfurizer blank are carried out by air-drying in a natural environment for 2 - 4 days, or drying in a hot air dryer at a temperature of 105 - 115 °C for 2 - 5 h.

10. Use of the calcium-based flue gas desulfurizer according to any one of claims 1 - 6, or the calcium-based flue gas desulfurizer prepared by the method according to any one of claims 7 - 9, for desulfurization of coke oven flue gas.

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