Pyrite roasting device and method for reducing sulfur trioxide conversion rate

Abstract

The invention discloses a pyrite roasting device and method for reducing the conversion rate of sulfur trioxide, which is characterized in that a conventional roasting furnace structure is optimized on the basis of a fluidization technology of conventional fluidized bed roasting, and a separation heat conduction sleeve and a separation cone are additionally arranged in an upstream separation section, and a novel material guide and air distribution system is arranged in a boiling section, so that the conversion rate of sulfur trioxide is reduced. The ore grain conveying path is adjusted according to roasted ore grains, secondary upward hot air conveying and stirring actions are matched, the roasted ore grains are promoted to fully diffuse downwards and float upwards along with airflow to be combusted, furnace gas and the roasted ore grains generated in the process are rapidly separated and pumped out, the residence time of the furnace gas in the furnace is shortened, the sulfur trioxide conversion rate is reduced, and the sulfur trioxide conversion rate is increased. And part of roasted ore grains are separated to the top of the preheating cavity along with furnace gas and are downwards and spirally conveyed together with newly-fed ore grains, so that the newly-fed ore grains are preheated, the roasting reaction conditions are quickly met, and the roasting process is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of pyrite roasting for sulfuric acid production, and more specifically, to a pyrite roasting device and method for reducing the conversion rate of sulfur trioxide. Background Art

[0002] Sulfuric acid is one of the important products in the basic chemical industry and is widely used in industrial sectors such as petroleum refining, metallurgy, agricultural fertilizer production, coking chemical industry, electroplating industry, tanning industry, rubber, paper making, paint, explosives, lead-acid battery manufacturing, dyes, pharmaceuticals, etc., and some modern cutting-edge scientific fields. Pyrite is the most important raw material for current sulfuric acid production. The fluidized bed roasting furnace is often used to roast pyrite to produce SO2 gas, and industrial sulfuric acid is produced from the SO2 gas.

[0003] The furnace gas obtained by roasting pyrite contains not only sulfur dioxide but also sulfur trioxide, moisture, and dust, etc. Among them, sulfur trioxide is further converted from sulfur dioxide. This is because generally, through a single feed on one side of the furnace bottom, the temperature of the newly introduced pyrite particles is relatively low, and the pyrite particles are likely to accumulate in the fluidized section. On the one hand, it is difficult to quickly achieve the roasting reaction conditions for the ore particles. On the other hand, the pyrite particles are not easily fully diffused and blown to the upper straight section, and the generated furnace gas is not easy to move upward quickly, resulting in poor gas-solid separation effect. As a result, the furnace gas stays in the furnace for a long time, which easily causes the sulfur dioxide in the furnace gas to be converted into sulfur trioxide. And sulfur trioxide is a strongly corrosive gas. In the presence of high temperature and water vapor, sulfur trioxide will directly react with water to generate sulfuric acid in advance, and sulfuric acid will cause serious corrosion to the roasting equipment. On the other hand, it reduces the content of sulfur dioxide in the furnace gas and affects the subsequent sulfuric acid production. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems, and now a pyrite roasting device and method for reducing the conversion rate of sulfur trioxide are provided.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A pyrite roasting device for reducing the conversion rate of sulfur trioxide, comprising a roasting furnace composed of an upward separation section, a conical transition section, and a fluidized section. A material guiding and air distribution system is provided in the fluidized section. A separation heat conduction sleeve coaxially arranged with it is fixedly installed inside the upward separation section, and a preheating cavity is reserved between the outer wall of the separation heat conduction sleeve and the inner wall of the upward separation section;

[0006] One side of the top of the upward separation section is provided with a feed port communicating with the preheating cavity. A spiral conveyor belt with the top connected to one side of the feed port is fixedly sleeved inside the preheating cavity. The bottom wall of the preheating cavity is fixedly installed with a sieve plate inclined downward to one side, and the upper inclined end of the sieve plate is located below the lower outlet of the spiral conveyor belt;

[0007] A separation cone is fixedly installed on the top of the separation heat-conducting sleeve, and a stirring assembly extending to the inside of the boiling section is rotatably installed on the bottom end of the separation cone. An upper material guide hood fixedly connected with the stirring assembly is rotatably installed on the bottom end of the separation heat-conducting sleeve. A plurality of overflow ports connected with the preheating chamber are annularly opened on the side wall at the top end of the separation heat-conducting sleeve, and a drainage sleeve is installed on the top of the preheating chamber, and a furnace gas outlet is provided at the top of the ascending separation section.

[0008] Furthermore, the material guiding and air distributing system includes a lower material guiding hood fixedly mounted on the bottom end of the conical transition section, the bottom end of the lower material guiding hood having an air distribution hood extending downward and fixed thereto, a lower combustion-supporting air duct being arranged below the air distribution hood, and an upper combustion-supporting air duct being arranged above the lower combustion-supporting air duct penetrating the lower material guiding hood and extending upward.

[0009] Furthermore, the lower material guide hood is a hollow conical structure that is wide at the top and narrow at the bottom, and the air distribution hood is a hollow conical structure that is connected to the bottom end of the lower material guide hood and is narrow at the top and wide at the bottom. A cooling space is formed between the air distribution hood, the outer side of the lower material guide hood and the inner wall of the boiling section, and cooling pipes are arranged in the cooling space.

[0010] Furthermore, the stirring assembly includes a stirring shaft rotatably mounted on the bottom of the separation cone and extending to the top of the lower combustion-supporting air duct, and a plurality of groups of stirring blades staggered up and down are fixed on the stirring shaft.

[0011] Furthermore, the upper material guide cover is a hollow conical structure that is wide at the top and narrow at the bottom and matches the structure of the lower material guide cover, and the lower end outlet of the upper material guide cover is farther away from the axial direction of the stirring shaft than the lower end outlet of the lower material guide cover.

[0012] Furthermore, the inner wall of the upper material guide cover is fixedly connected to the stirring shaft through a plurality of armature rods, and a plurality of material-shifting pieces movably fitted with the inner wall of the conical transition section are annularly distributed on the outer end wall of the upper material guide cover.

[0013] The present invention also provides a pyrite roasting method for reducing sulfur trioxide conversion rate, comprising the following steps:

[0014] S1. Spiral diffusion feeding: The ore particles are put into the preheating chamber from the feeding port, and the ore particles are diffused downward along the spiral direction of the spiral conveyor belt for preheating, and dispersedly added into the boiling section;

[0015] S2. Secondary upward hot air delivery: The combustion-supporting gas is supplied upward from multiple angles and directions by the lower combustion-supporting air duct and the upper combustion-supporting air duct. Under the action of the airflow, the ore particles form a boiling fluidized state. In this process, the stirring component is used to stir the ore particles to improve the diffusion degree of the ore particles, accelerate the generation speed of furnace gas and the separation speed of furnace gas and roasted ore particles;

[0016] S3. Circulating preheating of roasted ore particles: Part of the roasted ore particles are transported to the preheating chamber with the furnace gas, separated by the drainage sleeve, the furnace gas is discharged from the furnace gas outlet, and the roasted ore particles fall onto the spiral conveyor belt and are spirally conveyed downward together with the newly charged ore particles, playing a role of mixing and preheating the newly charged ore particles and enabling them to quickly reach the roasting reaction conditions.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] 1. This solution is based on the fluidization technology of conventional fluidized roasting, optimizes and improves the structure of the conventional roasting furnace. mainly by adding a separation heat conduction sleeve and a separation cone inside the upward separation section and setting a new type of material guiding and air distribution system inside the fluidized section, and matching the roasted ore particles with secondary upwardly conveyed hot air and stirring actions. The purpose is to promote the full downward diffusion of the roasted ore particles and floating combustion with the airflow. The furnace gas generated in this process is quickly separated and extracted from the roasted ore particles, reducing the residence time of the furnace gas in the furnace, that is, reducing the long-term contact between sulfur dioxide and oxygen, reducing the conversion rate of sulfur trioxide conversion rate. Part of the roasted ore particles are separated to the top of the preheating chamber with the furnace gas and are spirally conveyed downward together with the newly charged ore particles, playing a role of mixing and preheating the newly charged ore particles and enabling them to quickly reach the roasting reaction conditions.

[0019] 2. For the material guiding and air distribution system, through the settings of the air distribution hood, the lower material guiding hood, and the upper combustion-supporting air pipes and lower combustion-supporting air pipes distributed up and down, the ore particles are preheated from top to bottom and then diffused onto the lower material guiding hood, adjusting the conveying path of the ore particles. Compared with the conventional single feeding from one side of the furnace bottom, the diffusion degree of the ore particles in the fluidized section is improved. On this basis, with the cooperation of the vertical air supply in the middle and the inclined upward air supply at the edge, it helps to float the ore particles upward for combustion and improve the combustion-supporting effect. And the roasted ore particles separated and falling into the separation heat conduction sleeve fall on the upper material guiding hood for buffering and diffusion, and the upper combustion-supporting air pipes supply secondary upward inclined air, increasing the combustion temperature at the conical transition section and accelerating the generation speed of sulfur dioxide in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the external structure of the present invention;

[0021] Figure 2 is a partial cross-sectional view of the present invention;

[0022] Figure 3 is a schematic diagram of the structure of the present invention when the furnace body and the separation heat conduction sleeve and other structures are disassembled;

[0023] Figure 4 is a bottom view of the combination of the separation heat conduction sleeve, the stirring assembly and the upper material guiding hood of the present invention;

[0024] Figure 5 is a partial cross-sectional view of the combination of the separation heat conduction sleeve, the stirring assembly and the upper material guiding hood of the present invention;

[0025] Figure 6 It is an overall internal cross-sectional view of the present invention;

[0026] Figure 7 It is a cross-sectional schematic diagram of the present invention when working.

[0027] Description of the numbers in the figure:

[0028] 1. Ascending separation section; 101. Feed inlet; 102. Furnace gas outlet; 2. Conical transition section; 3. Boiling section; 301. Slag outlet; 4. Gas distribution hood; 5. Lower material guide hood; 6. Lower combustion-supporting air duct; 7. Upper combustion-supporting air duct; 8. Separation heat transfer sleeve; 801. Overflow port; 9. Spiral conveyor belt; 901. Baffle; 10. Screening plate; 11. Separation cone; 12. Stirring shaft; 13. Stirring blade; 14. Upper material guide hood; 15. Material shifting blade; 16. Drainage sleeve. DETAILED DESCRIPTION

[0029] The following will combine the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0030] Embodiment 1: In view of the fact that conventional roasting furnaces use a single feeding method on one side of the furnace bottom, it is difficult to achieve rapid roasting reaction conditions for the ore particles. On the other hand, the pyrite particles are not easy to be fully diffused and blown to the upper straight section, and the generated furnace gas is not easy to move upward quickly, resulting in poor gas-solid separation effect, which causes the furnace gas to stay in the furnace for a long time, which easily leads to the conversion of sulfur dioxide in the furnace gas into sulfur trioxide. The following technical solution is proposed:

[0031] The present invention discloses a pyrite roasting device for reducing sulfur trioxide conversion rate. Figure 1 , Figure 2 , comprising a roasting furnace consisting of an ascending separation section 1, a conical transition section 2, and a boiling section 3, wherein a material guiding and air distributing system is arranged inside the boiling section 3, a slag discharge port 301 is arranged on one side of the bottom end of the boiling section 3, a separation heat-conducting sleeve 8 arranged coaxially therewith is fixedly installed inside the ascending separation section 1, and a preheating chamber is reserved between the outer wall of the separation heat-conducting sleeve 8 and the inner wall of the ascending separation section 1;

[0032] A feed port 101 connected to the preheating chamber is provided on one side of the top of the ascending separation section 1, and a spiral conveyor belt 9 is fixedly sleeved inside the preheating chamber, and the top end of the spiral conveyor belt 9 is connected to one side of the feed port 101. A screening plate 10 is fixedly installed on the bottom wall of the preheating chamber and is inclined downward to one side, and the inclined upper end of the screening plate 10 is located below the lower end outlet of the spiral conveyor belt 9.

[0033] Please refer to Figure 2 、 Figure 3 As shown in FIGS. and, the material guiding and air distributing system includes a lower material guiding cover 5 fixedly installed at the bottom end of the conical transition section 2. A gas distributing cover 4 is fixedly installed at the bottom end of the lower material guiding cover 5 and extends downward. A lower combustion-supporting air duct 6 is arranged below the gas distributing cover 4. An upper combustion-supporting air duct 7 that penetrates the lower material guiding cover 5 and extends upward is arranged above the lower combustion-supporting air duct 6. The lower material guiding cover 5 is a hollow conical structure that is wider at the top and narrower at the bottom. The gas distributing cover 4 is a hollow conical structure that is butt-jointed with the bottom end of the lower material guiding cover 5 and is narrower at the top and wider at the bottom. A cooling space is formed between the outer sides of the gas distributing cover 4 and the lower material guiding cover 5 and the inner wall of the boiling section 3. Cooling pipes are arranged in the cooling space, and the cooling pipes have the function of temperature adjustment. This is the prior art and will not be elaborated here;

[0034] Please refer to the original Figure 6 、 Figure 7 As shown in FIGS. and, the lower combustion-supporting air duct 6 includes a plurality of first intake nozzles arranged vertically upward in the middle of the bottom end of the boiling section 3 and a plurality of second intake nozzles annularly distributed at the edge and inclined upward toward the inclined surface of the gas distributing cover 4. The lower material guiding cover 5 includes a plurality of third intake nozzles arranged at the top of the boiling section 3 and penetrating the gas distributing cover 4 and inclined upward toward the middle of the bottom end of the separation and heat-conducting sleeve 8;

[0035] In this embodiment, the structure of the conventional roasting furnace is optimized and improved. mainly by adding a separation and heat-conducting sleeve 8, a separation cone 11 inside the upward separation section 1 and setting a new type of material guiding and air distributing system inside the boiling section 3. A preheating chamber is formed between the outer wall of the separation and heat-conducting sleeve 8 and the inner wall of the upward separation section 1. The separation and heat-conducting sleeve 8 is made of heat-conducting material. An upward separation space that is vertically connected to the conical transition section 2 and the boiling section 3 is formed inside the separation and heat-conducting sleeve 8;

[0036] During the roasting process, the annular preheating chamber has a certain temperature. Ore particles are introduced into the preheating chamber from the feed inlet 101 and are spirally conveyed downward by the spiral conveyor belt 9, prolonging the conveying time of the ore particles. The ore particles fall on the sieve tray 10 from the lower end of the spiral conveyor belt 9 and diffuse and move downward along the inclined surface of the sieve tray 10 toward both sides. In this process, it is beneficial to enable the ore particles added at a single position to uniformly fall into the conical transition section 2 along the circumferential direction of the preheating chamber and to be diffusely distributed once by the lower material guiding cover 5 at the bottom of the conical transition section 2, so that the ore particles are preheated before entering the inside of the boiling section 3, shortening the heating time of the ore particles in the roasting furnace and accelerating the generation speed of sulfur dioxide;

[0037] With the secondary upward conveying of hot air, the hot air is a combustion-supporting gas, effectively promoting the upward floating and combustion of the roasted ore particles that are fully diffused downward along with the air flow. The furnace gas generated in this process is quickly separated and extracted from the roasted ore particles in the upward separation space, reducing the residence time of the furnace gas in the furnace, that is, reducing the long-term contact between sulfur dioxide and oxygen and reducing the conversion rate of sulfur trioxide.

[0038] Example 2: On the basis of Example 1, the internal structure of the upper separation section 1 is further improved by adding a stirring and furnace gas discharge and separation structure to improve the roasting effect and the furnace gas separation effect, as follows:

[0039] Please refer to Figures 2-7 , a separation cone 11 is fixedly installed at the inner top of the separation heat conducting sleeve 8, a stirring assembly extending into the boiling section 3 is rotationally driven and installed at the bottom end of the separation cone 11, an upper material guiding cover 14 fixedly connected to the stirring assembly is rotationally installed at the bottom end of the separation heat conducting sleeve 8, a plurality of air overflow ports 801 communicated with the preheating chamber are annularly formed in the side wall of the top end of the separation heat conducting sleeve 8, a drainage sleeve 16 is installed at the top of the preheating chamber, and a furnace gas outlet 102 is arranged at the top end of the upper separation section 1.

[0040] The stirring assembly includes a stirring shaft 12 rotatably installed at the bottom of the separation cone 11 and extending above the lower combustion air duct 6, a plurality of groups of stirring vanes 13 are fixedly arranged on the stirring shaft 12 and are distributed in a staggered manner up and down. The upper material guiding cover 14 is a hollow conical structure with a wider upper part and a narrower lower part adapted to the structure of the lower material guiding cover 5, and the lower end outlet of the upper material guiding cover 14 is further away from the axis direction of the stirring shaft 12 than the lower end outlet of the lower material guiding cover 5. The inner wall of the upper material guiding cover 14 is fixedly connected to the stirring shaft 12 through a plurality of connecting rods, and a plurality of feeding vanes 15 movably attached to the inner wall of the conical transition section 2 are annularly distributed on the outer end wall of the upper material guiding cover 14.

[0041] Combined with the technical solution of Example 1, the following solutions are set in this example for description:

[0042] During the roasting process, the stirring shaft 12 drives the stirring vanes 13 and the upper material guiding cover 14 to rotate synchronously. The stirring assembly composed of the stirring shaft 12 and the stirring vanes 13 stirs and diffuses the ore particles, accelerating the generation speed of furnace gas and the separation speed of furnace gas and roasted ore particles;

[0043] During the process that the roasted ore particles float up with the furnace gas and overflow from the plurality of air overflow ports 801, some roasted ore particles contact the separation cone 11 and fall to achieve separation from the furnace gas, and the roasted ore particles return to the boiling section 3 again. During this process, the roasted ore particles fall on the rotating upper material guiding cover 14, improving the diffusion degree of the reflux roasted ore particles. The plurality of upwardly inclined upper combustion air ducts 7 act on the reflux roasted ore particles, increasing the roasting temperature at the conical transition section 2 to expand the fluidized bed layer range, thereby further improving the roasting effect;

[0044] Partially roasted ore particles move to the preheating chamber with the furnace gas through the air overflow port 801. During the upward movement with the furnace gas, separation occurs at the drainage sleeve 16. An exhaust space is provided inside the drainage sleeve 16, and a separation surface that slopes inwardly on the outside of the exhaust space realizes the separation of the roasted particles. The roasted particles separated by gravity fall onto the spiral conveyor belt 9 and are mixed with the newly input ore particles and move downward along the spiral direction together;

[0045] Regarding the preheating link at this point, it should be noted that the roasted particles separated by external circulation, on the one hand, play a role in mixing and preheating the newly input ore particles, enabling them to quickly reach the roasting reaction conditions, shortening the heating time of the ore particles in the roasting furnace, and accelerating the generation rate of sulfur dioxide. On the other hand, the temperature of the roasted ore particles is synchronously reduced. The reduction in temperature will keep the reaction rate constant in a range more favorable for the generation of sulfur dioxide. The conversion of sulfur dioxide to sulfur trioxide usually requires an oxidation reaction, and the oxidation reaction often requires a relatively high activation energy and specific temperature conditions. Therefore, at a lower temperature, the rate of the oxidation reaction will significantly slow down, which is not conducive to the conversion of sulfur dioxide to sulfur trioxide.

[0046] Combined with Example 1 and Example 2, a pyrite roasting method for reducing the conversion rate of sulfur trioxide includes the following steps:

[0047] S1. Spiral diffusion feeding: Ore particles are input into the preheating chamber from the feeding port 101, and the ore particles are preheated by diffusing downward along the spiral direction of the spiral conveyor belt 9 and are dispersed and added to the boiling section 3;

[0048] S2. Secondary upward hot air delivery: Combustion-supporting gas is supplied upward from the lower combustion-supporting air pipeline 6 and the upper combustion-supporting air pipeline 7 at multiple angles and in multiple directions. Under the action of the air flow, the ore particles form a boiling fluidized state. During this process, the stirring component is used to stir the ore particles to improve the diffusion degree of the ore particles and accelerate the generation rate of furnace gas and the separation rate of furnace gas from the roasted ore particles;

[0049] S3. Circulating preheating of roasted ore particles: Part of the roasted ore particles are transported to the preheating chamber with the furnace gas and are separated by the drainage sleeve 16. The furnace gas is discharged from the furnace gas outlet 102, and the roasted ore particles fall onto the spiral conveyor belt 9 and are spirally transported downward together with the newly input ore particles, playing a role in mixing and preheating the newly input ore particles and enabling them to quickly reach the roasting reaction conditions.

[0050] In summary: Based on the fluidization technology of conventional boiling roasting, the structure of the conventional roasting furnace is optimized and improved. mainly by adding a separation heat conduction sleeve 8, a separation cone 11 inside the upward separation section 1 and setting a new type of material guiding and air distribution system inside the boiling section 3, adjusting the ore particle conveying path for the roasted ore particles, and combining with secondary upward hot air delivery and stirring actions, the purpose is to promote the full downward diffusion of the roasted ore particles and their floating combustion with the air flow;

[0051] The furnace gas generated by this process is quickly separated and extracted from the roasted ore particles in the separation heat-conducting sleeve 8, reducing the residence time of the furnace gas in the furnace, that is, reducing the long-time contact between sulfur dioxide and oxygen, lowering the conversion rate of sulfur trioxide, and part of the roasted ore particles are separated with the furnace gas to the top of the preheating chamber and spirally conveyed downward together with the newly charged ore particles, playing a role of mixing and preheating the newly charged ore particles and enabling them to quickly reach the conditions for the roasting reaction.

[0052] The above; only the preferred specific implementation manner of the present invention; however, the protection scope of the present invention is not limited thereto; any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved conceptions, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. A pyrite roasting device for reducing the conversion rate of sulfur trioxide, comprising a roasting furnace composed of an upward separation section (1), a conical transition section (2), and a boiling section (3), characterized in that: The boiling section (3) is provided with a material guiding and air distributing system, the upward separation section (1) is provided with a separation heat-conducting sleeve (8) coaxially arranged therewith, and a preheating chamber is reserved between the outer wall of the separation heat-conducting sleeve (8) and the inner wall of the upward separation section (1); A feed port (101) communicating with the preheating chamber is provided at one side of the top end of the upward separation section (1); a spiral conveyor belt (9) is fixedly sleeved inside the preheating chamber and the top end is connected to one side of the feed port (101); a sieve plate (10) is fixedly installed on the bottom end wall of the preheating chamber and is arranged to be inclined downward to one side, and the inclined upper end of the sieve plate (10) is located below the lower end outlet of the spiral conveyor belt (9); A separation cone (11) is fixedly installed at the top of the separation heat-conducting sleeve (8); a stirring assembly extending into the boiling section (3) is rotatably installed at the bottom of the separation cone (11); an upper material guide hood (14) fixedly connected to the stirring assembly is rotatably installed at the bottom of the separation heat-conducting sleeve (8); a plurality of overflow ports (801) connected to the preheating chamber are annularly provided on the top side wall of the separation heat-conducting sleeve (8); a discharge sleeve (16) is installed at the top of the preheating chamber; and a furnace gas outlet (102) is provided at the top of the ascending separation section (1).

2. The pyrite roasting device for reducing the conversion rate of sulfur trioxide according to claim 1, characterized in that: The material guiding and air distributing system comprises a lower material guiding hood (5) fixedly mounted at the bottom end of the conical transition section (2); a downwardly extending and fixed air distributing hood (4) is fixed at the bottom end of the lower material guiding hood (5); a lower combustion-supporting air duct (6) is arranged below the air distributing hood (4); and an upper combustion-supporting air duct (7) is arranged above the lower combustion-supporting air duct (6) and passes through the lower material guiding hood (5) and extends upward.

3. The pyrite roasting device for reducing the conversion rate of sulfur trioxide according to claim 2, characterized in that: The lower material guide cover (5) is a hollow conical structure that is wide at the top and narrow at the bottom, and the air distribution cover (4) is a hollow conical structure that is connected to the bottom end of the lower material guide cover (5) and is narrow at the top and wide at the bottom.

4. A pyrite roasting device for reducing the conversion rate of sulfur trioxide, characterized in that: The stirring assembly comprises a stirring shaft (12) rotatably mounted at the bottom of the separation cone (11) and extending to the top of the lower combustion-supporting air duct (6), and a plurality of groups of stirring blades (13) staggered up and down are fixed on the stirring shaft (12).

5. A pyrite roasting device for reducing the conversion rate of sulfur trioxide, characterized in that: The upper material guide cover (14) is a hollow conical structure that is wide at the top and narrow at the bottom and is compatible with the structure of the lower material guide cover (5), and the lower end outlet of the upper material guide cover (14) is farther away from the axial direction of the stirring shaft (12) than the lower end outlet of the lower material guide cover (5).

6. A pyrite roasting device for reducing the conversion rate of sulfur trioxide, characterized in that: The inner wall of the upper material guide cover (14) is fixedly connected to the stirring shaft (12) via a plurality of armature rods, and a plurality of material shifting pieces (15) movably fitted with the inner wall of the conical transition section (2) are annularly distributed on the outer end wall of the upper material guide cover (14).

7. A pyrite roasting method for reducing the conversion rate of sulfur trioxide, which uses a pyrite roasting device for reducing the conversion rate of sulfur trioxide as described in any one of claims 1-6, characterized in that, The steps include: S1, spiral diffusion feeding: the ore particles are fed into the preheating chamber from the feeding port (101), the ore particles are diffused downward along the spiral direction of the spiral conveyor belt (9) for preheating, and then dispersed and fed into the boiling section (3); S2, secondary upward hot air delivery: the combustion-supporting gas is supplied upward from multiple angles and directions by the lower combustion-supporting air duct (6) and the upper combustion-supporting air duct (7). Under the action of the airflow, the ore particles are in a boiling fluidized state. In this process, the ore particles are stirred by a stirring component to increase the diffusion degree of the ore particles, accelerate the generation speed of furnace gas and the separation speed of furnace gas and roasted ore particles; S3. Circulating preheating of roasted ore particles: Part of the roasted ore particles are transported to the preheating chamber along with the furnace gas, separated by the drainage sleeve (16), the furnace gas is discharged from the furnace gas outlet (102), and the roasted ore particles fall onto the spiral conveyor belt (9), and are spirally conveyed downward together with the newly charged ore particles, playing a role in mixing and preheating the newly charged ore particles, so that they quickly reach the conditions for roasting reaction.

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