A double-chamber rotary hearth furnace for recovering zinc from steelmaking dust and sludge

Abstract

A double-cavity rotary hearth furnace for recovering zinc from steelmaking dust and sludge is disclosed, belonging to the field of zinc-containing iron solid waste recycling. Multiple combustion nozzles are installed inside the furnace wall, and a preheating chamber with conveyor rollers is located on the side wall surrounding the furnace. A flue gas conveying pipe communicating with the preheating chamber is located at the top of the furnace wall. A fixed cylinder is located at the center of the rotating chassis, and a flue gas confluence channel communicating with the flue gas conveying pipe is formed inside the fixed cylinder. The surface of the rotating chassis forms staggered sintering chambers and heat storage zones. This invention uses a rotary hearth furnace instead of a rotary kiln, allowing raw materials to participate in sintering without needing to be processed into special pellets. Furthermore, the sintering flue gas is used to preheat the billets, which not only reduces the energy consumption caused by sintering pellets but also effectively utilizes the waste heat of the flue gas.

Description

Technical Field

[0001] This invention relates to the field of recycling zinc-containing iron solid waste, specifically to a double-chamber rotary hearth furnace for recovering zinc from steelmaking dust and sludge. Background Technology

[0002] Metallurgical dust generally contains high levels of iron, which has recycling value. However, it also contains varying degrees of harmful elements such as zinc, potassium, and sodium. Simply adding iron-containing dust to the sintering process will cause these harmful elements to accumulate within the blast furnace, leading to problems such as nodules on the upper part of the furnace body, upward-curving tuyeres, blockages in gas risers and baghouse dust collectors, and affecting the blast furnace's service life. Therefore, the safe treatment and recycling of steel dust has become a common research direction both domestically and internationally.

[0003] The applicant's steelmaking process is a long-process steelmaking process, which mainly generates solid wastes such as blast furnace bag ash, blast furnace gravity ash, and steelmaking sludge during production. The applicant also purchases blast furnace gravity ash and bag ash from Xining, Wuhai, and other places. This zinc-containing iron solid waste has a high zinc content, allowing for the recovery of high-value elements. The resulting iron slag is also directly recycled in sintering and steelmaking processes.

[0004] In the existing technology, the treatment of zinc-containing iron solid waste generally adopts rotary kiln sintering treatment. It is necessary to first make zinc-containing iron solid waste into pellets and pre-sinter them to give them a certain strength, and then send them into the rotary kiln for high-temperature sintering in the temperature range of 1100-1300℃. Zinc enters the flue in the form of steam and eventually forms secondary zinc oxide, thereby extracting zinc, while iron is reduced. Although this processing method has a large processing capacity and high efficiency, it requires pre-forming and pre-sintering pellets, resulting in high energy consumption and relatively high processing costs. Moreover, since the raw materials are pre-formed into pellets, high-temperature sintering in the rotary kiln requires a long time to ensure that the raw materials inside the pellets participate in the reaction, further increasing energy consumption. In addition, incomplete reaction of the raw materials inside the pellets often occurs. Summary of the Invention

[0005] The purpose of this invention is to provide a double-chamber rotary hearth furnace for recovering zinc from steelmaking dust. By using a rotary hearth furnace instead of a rotary kiln, the raw materials can participate in sintering without needing to be processed into special pellets. Furthermore, the sintering flue gas is used to preheat the billets, which not only reduces energy consumption caused by sintering pellets but also effectively utilizes the waste heat of the flue gas. Simultaneously, by using a specially structured mold to produce the billets and sintering the billets and molds simultaneously, it not only helps the internal materials of the billets to be sintered quickly and thoroughly but also results in a loose material after sintering, reducing the difficulty of subsequent iron removal processes.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned technical objectives is as follows: a double-chamber rotary hearth furnace for recovering zinc from steelmaking dust, comprising a rotary hearth furnace body formed by a rotary base and a furnace wall, wherein a discharge furnace door and a feed furnace door are provided on the furnace wall, and multiple combustion nozzles are arranged inside the furnace wall corresponding to the position of the rotary base, and a conveying roller is arranged around the side wall of the furnace wall, which is located in a preheating chamber, and a preheating inlet is provided on the side wall at the first end of the preheating chamber, and a pushing structure is provided at the tail end of the preheating chamber. The feed furnace door is opened at the tail end of the preheating chamber, and after the feed furnace door is opened, the pushing structure pushes the formed billet into the feed furnace door; the preheating chamber is disconnected between the first and last ends, and the discharge furnace door is opened at the disconnection point between the first and last ends of the preheating chamber; A flue gas conveying pipe is provided on the top of the furnace wall, and the end of the flue gas conveying pipe is connected to the tail end of the preheating chamber. An exhaust port is provided above the head end of the preheating chamber. A fixed cylinder is set at the center of the rotary chassis. The interior of the fixed cylinder forms a flue gas collection channel, which is connected to the flue gas conveying pipe. Several partition plates are arranged around the outer wall of the fixed cylinder. These partition plates divide the surface of the rotary chassis into several cavities. Some cavities are filled with refractory material to form a heat storage zone, and the remaining cavities form a sintering cavity. The sintering cavity and the heat storage zone are arranged alternately. The sintering chamber is provided with a bottom plate parallel to its bottom surface, and the bottom plate divides the sintering chamber into an upper sintering zone and a lower flue gas flow channel. The bottom plate is provided with a channel connecting the sintering zone and the flue gas flow channel. Through holes are distributed on the side wall of the fixed cylinder at positions corresponding to the flue gas flow channel, so that the flue gas generated by the combustion of the combustion nozzle enters the flue gas delivery pipe in sequence through the flue gas flow channel, the through holes and the flue gas confluence channel, and then flows along the preheating chamber from the tail end to the head end, and finally exits the preheating chamber from the exhaust port.

[0007] As an optimized solution for the above-mentioned double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge, the rotary base and furnace wall form an acute angle with the horizontal plane, and the discharge furnace door is located at the lowest position of the furnace wall.

[0008] As another optimized solution for the above-mentioned double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge, a smoke passage gap is formed between the conveyor roller and the bottom of the preheating chamber.

[0009] As another optimized solution for the above-mentioned double-cavity rotary hearth furnace for zinc recovery from steelmaking dust and sludge, a conveyor roller power chamber is provided on the outer side of the preheating cavity.

[0010] As another optimized solution for the above-mentioned double-chamber rotary hearth furnace for zinc recovery from steelmaking dust, a stopping platform is provided in the preheating chamber at the position corresponding to the feeding furnace door.

[0011] As another optimized solution for the above-mentioned double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge, a smoke distribution plate is provided at the end of the flue gas conveying pipe that extends into the preheating chamber.

[0012] As another optimized solution for the above-mentioned double-cavity rotary hearth furnace for zinc recovery from steelmaking dust, a feeding roller conveyor is provided outside the preheating inlet, and a discharge roller conveyor is provided outside the discharge furnace door.

[0013] As another optimized solution for the above-mentioned double-cavity rotary hearth furnace for zinc recovery from steelmaking dust, the forming billet is composed of a forming mold and the material filling the forming mold. The forming mold includes a base plate, with an outer vertical plate and an inner vertical plate of equal height at both ends of the upper surface of the base plate. The base plate, the outer vertical plate, and the inner vertical plate enclose the mold space. Several horizontal support rods are distributed in the mold space, and each horizontal support rod is supported by several vertical support rods. Several heat-conducting elements are distributed along the length direction of the horizontal support rods. The two ends of these heat-conducting elements along their length direction are flush with the edge of the base plate between the outer vertical plate and the inner vertical plate.

[0014] As another optimized solution for the above-mentioned double-cavity rotary hearth furnace for zinc recovery from steelmaking dust, an upward extension plate is provided on the side of the top of the outer vertical plate away from the inner vertical plate, and a mounting platform is formed between the extension plate and the top of the outer vertical plate.

[0015] As another optimized solution for the above-mentioned double-cavity rotary hearth furnace for zinc recovery from steelmaking dust, the heat-conducting component includes a rhomboid body with a hollow cavity inside, and extended fins at both ends along the long axis of the rhomboid body.

[0016] Before the billet is made, the raw material, namely metallurgical dust, needs to be pretreated. For example, it is first washed with water to remove most of the oxides of calcium, sodium and potassium. Then the moist raw material is mixed with coke powder, and the moisture content is controlled at about 10-15%. The amount of coke powder added is 5-10%. The billet is not easy to melt at high temperature, reducing particle adhesion and finally forming a loose powdery sintered material, which is directly subjected to magnetic separation to recover iron.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention uses a rotary hearth furnace instead of a rotary kiln, so that the raw materials do not need to be made into special pellets before participating in sintering. Furthermore, the flue gas from sintering is used to preheat the billet, which not only reduces the energy consumption caused by sintering pellets, but also effectively utilizes the waste heat of the flue gas. At the same time, by using a mold with a special structure to make the billet and sintering the billet and the mold at the same time, it not only helps the material inside the billet to be sintered quickly and thoroughly, but also makes the sintered material loose, reducing the difficulty of the subsequent iron removal process. 2) The rotating chassis of the present invention is provided with a fixed cylinder at the center as a channel for collecting flue gas, and its surface is divided into several sintering chambers and heat storage zones. The presence of the heat storage zones can ensure the stability and uniformity of the temperature inside the furnace. A bottom plate is provided in the sintering chamber, and the bottom part of the bottom plate has a flue gas channel. The flue gas channel is connected to the bottom of the fixed cylinder, so that the flue gas generated by sintering moves downward and is discharged upward through the flue gas channel and the flue gas confluence channel in the fixed cylinder. In this process, the formed billet in the sintering chamber can be fully heated, which improves the heat utilization rate of the rotary hearth furnace. 3) The feeding furnace door of the present invention is located near the tail end of the preheating chamber. In this way, when the feeding furnace door is opened and the forming blank is pushed in, the heat in the rotary hearth furnace is also dissipated into the preheating chamber, which can effectively reduce the heat loss in the rotary hearth furnace caused by opening the furnace door. The flue gas moves from the tail end of the preheating chamber (i.e., near the feeding furnace door) to the head end of the preheating chamber (i.e., near the preheating inlet) and is discharged. During this process, the forming blank is preheated due to the countercurrent contact with the forming blank, thereby effectively utilizing the waste heat of the flue gas, and it will not cause the temperature near the preheating inlet to rise, thus improving the operating environment. 4) The present invention is in an inclined state and the discharge furnace door is at the lowest position, which not only facilitates the discharge of the sintered billet, but also allows the trajectory of the flue gas in the preheating chamber to first rise and then fall from the tail end to the head end, prolonging the residence time of the flue gas in the preheating chamber, so that the billet is fully preheated, and effectively reducing the temperature of the discharged flue gas. Even if some zinc vapor condenses into secondary zinc oxide due to the decrease in flue gas temperature during the preheating process, the generated secondary zinc oxide will condense on the surface of the formed billet and be sintered again, without waste. 5) The forming blank of the present invention includes a forming mold, that is, the blank and the mold are sintered simultaneously. By utilizing the mold itself and internal components such as vertical support rods and heat-conducting parts, heat can be quickly transferred to the interior of the blank, enabling the blank to complete synchronous sintering in a short time and preventing incomplete sintering inside the blank. By setting hollow cavities and extended fins on the heat-conducting parts, the thermal conductivity of the mold is significantly improved, thereby enabling the blank to be sintered simultaneously inside and out, increasing the sintering rate and reducing the sintering time. Furthermore, after sintering, the presence of the forming mold makes the blank loose, effectively reducing the difficulty of subsequent iron recycling. 6) Compared with the rotary kiln sintering process, this invention not only improves the production efficiency and sintering efficiency of the billet and reduces energy consumption, but also, compared with pre-sintered pellets, the billet manufactured by this invention can be fully sintered in a shorter time, and forms a loose material after sintering, which reduces the difficulty of recovering iron from it. Compared with the rotary kiln, the rotary hearth furnace of this invention has a smaller design size and a smaller amount of solid waste processed per batch, but it can achieve continuous solid waste treatment without reducing the treatment efficiency. Moreover, the miniaturization of the equipment reduces energy consumption and makes it more universal. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the external structure of the furnace wall and preheating cavity in this invention; Figure 2 This is a schematic diagram of the internal structure of the furnace wall and preheating cavity in this invention; Figure 3 A schematic diagram of the vertical cross-sectional structure of the furnace wall and the rotating chassis; Figure 4 This is a schematic diagram of the cross-sectional structure of the preheating cavity; Figure 5 This is a schematic diagram of the horizontal cross-sectional structure of the present invention; Figure 6 This is a top view of the molding die. Figure 7 for Figure 6 A frontal view diagram; Figure 8 This is a schematic diagram of the cross-sectional structure of the heat-conducting component; Reference numerals: 1. Rotary chassis; 101. Fixed cylinder; 102. Divider plate; 103. Heat storage zone; 104. Sintering chamber; 105. Flue gas confluence channel; 106. Opening area; 107. Bottom plate; 108. Flue gas flow channel; 109. Rotary shaft; 2. Preheating chamber; 201. Exhaust port; 202. Preheating inlet; 203. Conveying roller conveyor; 204. Stopping platform; 205. Pushing structure; 206. Feeding roller conveyor; 207. Flue gas passage gap; 2 08. Conveyor roller power chamber; 3. Furnace wall; 301. Discharge furnace door; 302. Feed furnace door; 303. Flue gas conveying pipe; 304. Combustion nozzle; 305. Discharge roller conveyor; 306. Smoke distribution plate; 4. Horizontal support rod; 5. Vertical support rod; 6. Heat-conducting component; 601. Rhomboid body; 602. Hollow cavity; 603. Extended wing; 7. Base plate; 8. Outer vertical plate; 801. Extended plate; 802. Carding platform; 9. Inner vertical plate; A. Formed blank. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not explained in the following embodiments of the present invention, such as the selection of electric push rods or hydraulic push rods, conveyor rollers and their supporting power equipment and control equipment, are considered to be prior art known or should be known by those skilled in the art.

[0020] Example 1

[0021] A double-cavity rotary hearth furnace for recovering zinc from steelmaking dust, such as Figure 1 and Figure 2As shown, the rotary hearth furnace body includes a rotary base 1 driven by a rotary shaft 109 and a furnace wall 3. The furnace wall 3 is actually a closed structure formed by side walls and a top wall, generally cylindrical, constructed of refractory bricks, enclosing the rotary base 1. A discharge furnace door 301 and a feed furnace door 302 are provided on the furnace wall 3. The discharge furnace door 301 and the feed furnace door 302 can adopt existing furnace door structures, their main purpose being to open the furnace doors for discharge or feed operations when needed. Multiple combustion nozzles 304 are installed inside the furnace wall 3 corresponding to the positions of the rotary base 1. The combustion nozzles 304 adopt existing combustion... The nozzles are sufficient; their related fuel supply pipelines, control equipment, ignition equipment, etc., are all conventional designs and will not be elaborated here. These combustion nozzles 304 are generally located at the top of the furnace wall 3 and are evenly distributed. A conveyor roller conveyor 203 is arranged around the side wall of the furnace wall 3. The conveyor roller conveyor 203 is composed of individual conveyor rollers, and each individual conveyor roller is driven by a power source to rotate synchronously with the other conveyor rollers. The conveyor roller conveyor 203 is located in a preheating chamber 2, which is an arc-shaped chamber built of refractory material. This arc-shaped chamber is arranged around the furnace wall 3, and its center is aligned with the center of the furnace wall 3. The preheating chamber 2 and the furnace wall 3 share the same sidewall. The preheating chamber 2 has a preheating inlet 202 at its front end and a pusher structure 205 at its rear end. The front and rear ends of the preheating chamber 2 are defined by the transmission direction of the conveyor roller 203; that is, the front end of the conveyor roller 203 in the transmission direction is called the front end, and the rear end is called the rear end. Both the front and rear ends of the preheating chamber 2 are closed. A closed door is provided on the preheating inlet 202. When feeding material into the conveyor roller 203 inside the preheating chamber 2, the door is opened. The feeding furnace door 302... The preheating chamber 2 is located at the tail end, i.e., the feeding furnace door 302 is inside the preheating chamber 2. After the feeding furnace door 302 is opened, the shaped blank A is pushed into the feeding furnace door 302 by the pushing structure 205. The pushing structure 205 uses an existing electric push rod to push the shaped blank A into the feeding furnace door 302 and finally push it onto the rotary base 1. The preheating chamber 2 is disconnected between the beginning and end, i.e., the preheating chamber 2 is not a complete ring, but is missing a section, so that the beginning and end are not connected. The discharge furnace door 301 is opened at the disconnection between the beginning and end of the preheating chamber 2, i.e., the discharge furnace door 301 is located at the gap between the beginning and end of the preheating chamber 2. like Figure 1As shown, a flue gas conveying pipe 303 is provided on the top of the furnace wall 3. The flue gas conveying pipe 303 can be located inside or outside the furnace wall 3, but its ends are connected to the inside of the furnace wall 3. The end of the flue gas conveying pipe 303 is connected to the tail end of the preheating chamber 2, thereby sending the flue gas generated by combustion in the furnace wall 3 into the preheating chamber 2. A flue gas exhaust port 201 is provided above the head end of the preheating chamber 2. The flue gas exhaust port 201 is connected to the flue gas treatment equipment to treat the flue gas so that it meets the emission standards before being discharged. like Figure 2 and Figure 3 As shown, a fixed cylinder 101 is provided at the center of the rotating chassis 1. The fixed cylinder 101 is a high-temperature resistant metal cylinder or a cylinder formed by refractory material. The bottom of the fixed cylinder 101 is fixed to the rotating chassis 1, and the top is open and concentric with the rotating chassis 1. A flue gas confluence channel 105 is formed inside the fixed cylinder 101. The flue gas confluence channel 105 is connected to one end of the flue gas conveying pipe 303 inside the furnace wall 3. In practice, since the rotating chassis 1 and the fixed cylinder 101 keep rotating, while the furnace wall 3 and the flue gas conveying pipe 303 on it remain stationary, in order to achieve the connection between the two, a cylinder is generally provided on the top wall inside the furnace wall. This cylinder is connected to the top of the fixed cylinder 101. The sealing connection can be achieved by nesting the parts together. One end of the flue gas conveying pipe 303 inside the furnace wall 3 is located within this cylinder, thus ensuring the connection between the fixed cylinder 101 and the flue gas conveying pipe 303. This allows the flue gas manifold 105 to connect with the flue gas conveying pipe 303. The main purpose of the seal is to prevent flue gas from directly entering the flue gas conveying pipe 303 through the gap between the fixed cylinder 101 and the top of the furnace wall 3. Several partition plates 102, distributed along the radius of the rotating chassis 1, are arranged around the outer wall of the fixed cylinder 101. The partition plates 102 are formed by high-temperature resistant metal or refractory material. These partition plates 102 divide the surface of the rotating chassis 1 into several cavities, such as... Figure 5 As shown, a heat storage zone 103 is formed by filling a portion of the cavity with refractory material, and the remaining cavity forms a sintering cavity 104. The sintering cavity 104 and the heat storage zone 103 are arranged alternately. The so-called alternate arrangement means that both sides of any sintering cavity 104 are heat storage zones 103, and similarly, both sides of any heat storage zone 103 are sintering cavities 104. like Figure 3As shown, a base plate 107 parallel to the bottom surface of the sintering chamber 104 is provided inside the sintering chamber 104. The base plate 107 is generally made of high-temperature resistant metal, and its surface is covered with refractory material. The base plate 107 divides the sintering chamber 104 into an upper sintering zone and a lower flue gas channel 108. The sintering zone is the working zone, where the formed blank A is sintered by the flame sprayed from the combustion nozzle 304. There are gaps between the formed blank A and the side wall of the sintering chamber 104. The height of the flue gas channel 108 is generally not less than 10cm. The base plate 107 is provided with channels connecting the sintering zone and the flue gas channel 108. These channels can be through grooves, through holes, or slots. Their purpose is to allow the flue gas generated in the sintering zone to pass through these channels and enter the flue gas channel 108. The channels are generally located at the edge of the base plate 107 to prevent blockage by the formed blank A. Several support members are provided inside the flue gas channel 108. These support members are generally The base plate 107 is constructed of refractory material and is supported by it. Through holes 106 are distributed on the side wall of the fixed cylinder 101 at positions corresponding to the flue gas flow channel 108. The shape of the through holes 106 can be arbitrary, such as round holes, square holes, slotted holes, strip holes, etc., so that the flue gas generated by the combustion of the combustion nozzle 304 enters the flue gas conveying pipe 303 through the flue gas flow channel 108, through holes 106 and flue gas confluence channel 105 in sequence, and then flows from the tail end to the head end in the preheating chamber 2. During the flow of the flue gas in the preheating chamber 2, it fills the entire cross section of the preheating chamber 2, thereby fully preheating the forming blank A on the conveying roller 203 in the preheating chamber 2, and finally exits the preheating chamber 2 from the exhaust port 201. The flue gas discharged from the exhaust port 201 first passes through some heat exchange and condensation equipment to condense zinc vapor into secondary zinc oxide. The remaining flue gas is treated by conventional desulfurization, denitrification and dust removal to meet the emission standards before being discharged.

[0022] In continuous production, the preheating chamber 2 has multiple shaped blanks A arranged on the conveyor rollers 203. The rotary chassis 1 rotates slowly and continuously according to a set speed, which is set after experimentation or calculation based on actual conditions. When a sintering chamber 104 rotates to the feeding furnace door 302, the feeding furnace door 302 opens, and the shaped blank A is pushed from the feeding furnace door 302 into the sintering chamber 104 on the rotary chassis 1. Then, the feeding furnace door 302 is closed. When the sintering chamber 104 rotates to the discharge furnace door 301, the sintering of the shaped blank A inside is completed. The discharge furnace door 301 is opened, and the sintered shaped blank A is pulled out of the sintering chamber 104 using an existing robotic arm. The discharge furnace door 301 is then closed. The sintering chamber 104 continues to rotate forward. When it reaches the feeding furnace door 302, the above process is repeated to complete continuous sintering. During this process, each time a shaped blank A is pushed into the feeding furnace door 302, the conveyor roller 203 in the preheating chamber 2 is activated for a certain period of time, causing all the shaped blanks A on it to move forward one position. Then, the preheating inlet 202 is opened, and a new shaped blank A is pushed into the preheating chamber 2, thus completing the continuous preheating and sintering.

[0023] The above are the basic embodiments of the present invention. Further improvements, optimizations, and limitations can be made based on the above to obtain the following embodiments: Example 2

[0024] This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1 , Figure 2 and Figure 3 As shown, the rotary base 1 and the furnace wall 3 form an acute angle with the horizontal plane, and the discharge furnace door 301 is located at the lowest position of the furnace wall 3. That is to say, the rotary base 1 is in an inclined state, and the corresponding furnace wall 3 is also in an inclined state. The inclination angle is generally no more than 20°, preferably 5-10°. This inclination not only facilitates the discharge of the sintered billet A, but also, because both the furnace wall 3 and the rotary base 1 are in an inclined state, the preheating chamber 2 is also in an inclined state. Due to the discharge furnace door 301... At the lowest point, correspondingly, the beginning and end ends of the preheating chamber 2 are located on both sides. The flue gas entering it goes through a process of rising first and then falling before it can be discharged from the exhaust port 201. This slows down the flow speed in the preheating chamber 2 and prolongs the residence time in the preheating chamber 2, thereby improving the heat exchange effect between the flue gas and the forming billet A in the preheating chamber 2. During this process, even if a small part of zinc vapor condenses to produce secondary zinc oxide, it will adhere to the surface of the forming billet A and re-enter the furnace wall 3 for sintering, without causing the loss of secondary zinc oxide.

[0025] Example 3

[0026] This embodiment is an improved version based on embodiment 1. Its main structure is the same as that of embodiment 1, but the improvement lies in: [The following is a more detailed description of the improvement.] Figure 1 , Figure 2 and Figure 3 As shown, a smoke passage gap 207 is formed between the bottom of the conveyor roller 203 and the bottom of the preheating chamber 2. Under normal circumstances, the distance between the bottom of the conveyor roller 203 and the bottom of the preheating chamber 2 is 15-30cm. When the forming blank A is placed on the conveyor roller 203, the distance between the top of the forming blank A and the top of the preheating chamber 2 cannot exceed the distance between the bottom of the conveyor roller 203 and the bottom of the preheating chamber 2, which is generally 10-20cm. This smoke layout with a narrow top and a wide bottom can cause a portion of the smoke to pass through the smoke passage gap 207 at the bottom, thus completing the coating and preheating of the forming blank A. like Figure 4 As shown, a conveyor roller power chamber 208 is provided on the outside of the preheating chamber 2. The conveyor roller power chamber 208 is generally a closed chamber formed by masonry, or it can be made of metal material to form a closed shell. A power device for driving the conveyor roller 203 is provided in the conveyor roller power chamber 208. The conveyor roller 203 and the power device that drives its rotation can adopt existing mature technology. In order to facilitate the maintenance of the power device, an inspection door can be opened on the conveyor roller power chamber 208 to facilitate personnel to enter the interior for repair and maintenance. like Figure 5 As shown, a stopping platform 204 is provided in the preheating chamber 2 at a position corresponding to the feeding furnace door 302. The stopping platform 204 is located between the pushing structure 205 and the feeding furnace door 302, and at the end of the conveying roller conveyor 203. The stopping platform 204 is not provided with the conveying roller conveyor 203. The surface of the stopping platform 204 is flush with the surface of the conveying roller conveyor 203, so that the conveying roller conveyor 203 conveys the formed blank A to the stopping platform 204. like Figure 2 As shown, a smoke distribution plate 306 is provided at the end of the flue gas conveying pipe 303 that extends into the preheating chamber 2. The smoke distribution plate 306 is a hollow metal shell, and its shape is a long and thin tube or a rectangle. It is installed at the top of the preheating chamber 2, and its length direction is parallel to the conveying roller 203. Through holes are distributed on the surface of the smoke distribution plate 306 facing the conveying roller 203. Of course, the smoke distribution plate 306 can also be set at the bottom of the preheating chamber 2 and exhaust smoke upward, as long as it does not affect the transmission of the forming blank A by the conveying roller 203. like Figure 5 As shown, a feeding roller conveyor 206 is provided outside the preheating inlet 202. The feeding roller conveyor 206 can be an existing conveyor roller conveyor, and its power and control system will not be described in detail. The feeding roller conveyor 206 is used to convey the shaped blank A into the preheating chamber 2 after the preheating inlet 202 is opened. A discharge roller conveyor 305 is provided outside the discharge furnace door 301. The discharge roller conveyor 305 is also an existing conveyor roller conveyor, and its power and control system will not be described in detail. The discharge roller conveyor 305 is used to pull the sintered shaped blank A out of the discharge furnace door 301 and place it on the discharge roller conveyor 305 after the discharge furnace door 301 is opened, and then be conveyed to the next process by the discharge roller conveyor 305. The robot is an existing mature mechanical device, which can be manually controlled or automatically controlled. Its purpose is to reach into the discharge furnace door 301 and pull out the shaped blank A.

[0027] Example 4

[0028] The molding blank A used in the above embodiments is composed of a molding die and the material filling the molding die, wherein, for example Figure 6 and Figure 7As shown, the molding die includes a base plate 7, which is made of high-temperature resistant metal and generally has a length direction. At both ends of the upper surface of the base plate 7, there are outer vertical plates 8 and inner vertical plates 9 of equal height. The outer vertical plates 8 and inner vertical plates 9 are also made of high-temperature resistant metal and are located at the ends of the length direction. Opposite to the length direction is the width direction. The base plate 7, outer vertical plates 8, and inner vertical plates 9 enclose a mold space. Opening areas are formed on both sides of the mold space, i.e., opening areas are formed on both sides of the width direction of the base plate 7. Several transverse support rods 4 are distributed within the mold space. The transverse support rods 4 are made of high-temperature resistant metal and are generally distributed along the length direction of the base plate 7. Each transverse support rod 4 is supported by several vertical support rods 5, which are also made of high-temperature resistant metal, thereby ensuring the transverse support... The rod 4 is detached from the base plate 7 and is located within the mold space. The transverse support rod 4 can be at different heights in different positions within the mold space, or at the same height in different positions. The transverse support rod 4 can be horizontal with the base plate 7 or in an inclined state. At most one end of these transverse support rods 4 is fixed to the outer vertical plate 8 or the inner vertical plate 9. In a preferred embodiment, one end of the transverse support rod 4 is fixed and the other end is suspended, and the fixed ends of two adjacent transverse support rods 4 are on opposite sides. Several heat-conducting elements 6 are distributed along the length direction of the transverse support rod 4. The heat-conducting elements 6 are made of high-temperature resistant metal. The two ends of these heat-conducting elements 6 in the length direction are flush with the edge of the base plate 7 between the outer vertical plate 8 and the inner vertical plate 9, that is, the two ends of the heat-conducting elements 6 in the length direction are flush with the two sides of the base plate 7 in the width direction.

[0029] In this embodiment, the bottom plate 7 is an isosceles trapezoid. In practice, the two waistlines of the isosceles trapezoid are parallel to the inner wall of the sintering cavity in the rotary hearth furnace, but there is a gap between it and the side wall of the sintering cavity. The outer vertical plate 8 is fixedly connected to the longer end of the bottom plate 7, and the inner vertical plate 9 is fixedly connected to the shorter end of the bottom plate 7.

[0030] In this embodiment, the bottom of the vertical support rod 5 is fixed to the upper surface of the base plate 7, usually by welding. The two edges are flush with the two sides of the base plate 7, and the top end does not exceed the height of the outer vertical plate 8 and the inner vertical plate 9. Generally, the height of the vertical support rod 5 is slightly lower than the height of the outer vertical plate 8 and the inner vertical plate 9, or it can be flush with them. The vertical support rod 5 is a diamond-shaped hollow rod, and additional winglets can be provided on both sides of it, with its top end closed.

[0031] In this embodiment, as Figure 7 As shown, an upward extension plate 801 is provided on the side of the top of the outer vertical plate 8 away from the inner vertical plate 9. The extension plate 801 is vertically upward and is an integral structure with the outer vertical plate 8. The thickness of the extension plate 801 is generally about half the thickness of the outer vertical plate 8. A locking platform 802 is formed between the extension plate 801 and the top of the outer vertical plate 8.

[0032] In this embodiment, as Figure 8As shown, the heat-conducting component 6 includes a rhomboid body 601, the acute angle of which is generally 20-50°. A hollow cavity 602 is formed inside the rhomboid body 601. The hollow cavity 602 is open at both ends, and there are extended fins 603 at both ends along the long axis of the rhomboid body 601. The extended fins 603 are the same length as the rhomboid body 601.

[0033] In this embodiment, before the billet is made, the raw material, namely metallurgical dust, needs to be pretreated, such as by washing with water to remove most of the oxides of calcium, sodium and potassium. Then the moist raw material is mixed with coke powder, and the moisture content is controlled at about 10-15%. The amount of coke powder added is 5-10%. The billet is not easy to melt at high temperature, reducing particle adhesion and finally forming a loose powdery sintered material, which is then directly subjected to magnetic separation to recover iron.

Claims

1. A double-chamber rotary hearth furnace for recovering zinc from steelmaking dust, comprising a rotary hearth furnace body formed by a rotary base (1) and a furnace wall (3), wherein a discharge furnace door (301) and a feed furnace door (302) are provided on the furnace wall (3), and multiple combustion nozzles (304) are arranged inside the furnace wall (3) corresponding to the position of the rotary base (1), characterized in that: A conveyor roller (203) is provided around the side wall of the furnace wall (3). The conveyor roller (203) is located in a preheating chamber (2). A preheating inlet (202) is provided on the side wall at the beginning of the preheating chamber (2). A pushing structure (205) is provided at the end of the preheating chamber (2). The feeding furnace door (302) is opened at the end of the preheating chamber (2). After the feeding furnace door (302) is opened, the pushing structure (205) pushes the formed blank (A) into the feeding furnace door (302). The preheating chamber (2) is disconnected at the beginning and end. The discharge furnace door (301) is opened at the disconnection point between the beginning and end of the preheating chamber (2). The top of the furnace wall (3) is provided with a flue gas conveying pipe (303), the end of the flue gas conveying pipe (303) is connected to the tail end of the preheating chamber (2), and the top of the preheating chamber (2) is provided with a flue gas outlet (201). A fixed cylinder (101) is provided at the center of the rotary chassis (1). A flue gas confluence channel (105) is formed inside the fixed cylinder (101). The flue gas confluence channel (105) is connected to the flue gas conveying pipe (303). Several partition plates (102) are arranged around the outer wall of the fixed cylinder (101). These partition plates (102) divide the surface of the rotary chassis (1) into several cavities. Some cavities are filled with refractory material to form a heat storage zone (103). The remaining cavities form a sintering cavity (104). The sintering cavity (104) and the heat storage zone (103) are arranged alternately. The sintering chamber (104) is provided with a bottom plate (107) parallel to its bottom surface, and the bottom plate (107) divides the sintering chamber (104) into an upper sintering zone and a lower flue gas flow channel (108). The bottom plate (107) is provided with a channel connecting the sintering zone and the flue gas flow channel (108). The side wall of the fixed cylinder (101) is provided with through holes (106) at positions corresponding to the flue gas flow channel (108), so that the flue gas generated by the combustion of the combustion nozzle (304) enters the flue gas conveying pipe (303) through the flue gas flow channel (108), the through holes (106) and the flue gas confluence channel (105) in sequence, and then flows from the tail end to the head end in the preheating chamber (2), and finally exits the preheating chamber (2) from the exhaust port (201). The molding blank (A) is composed of a molding mold and the material filling the molding mold. The molding mold includes a base plate (7). At both ends of the upper surface of the base plate (7), there are outer vertical plates (8) and inner vertical plates (9) of equal height. The base plate (7), outer vertical plates (8) and inner vertical plates (9) enclose the mold space. Several horizontal support rods (4) are distributed in the mold space. Each horizontal support rod (4) is supported by several vertical support rods (5). Several heat-conducting components (6) are distributed along the length direction of the horizontal support rods (4). The two ends of these heat-conducting components (6) are flush with the edge of the base plate (7) between the outer vertical plates (8) and the inner vertical plates (9).

2. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: The rotary chassis (1) and the furnace wall (3) form an acute angle with the horizontal plane, and the discharge furnace door (301) is located at the lowest position of the furnace wall (3).

3. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: A smoke passage gap (207) is formed between the conveyor roller (203) and the bottom of the preheating chamber (2).

4. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: The preheating chamber (2) is provided with a conveyor roller power chamber (208) on the outside.

5. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: A stopping platform (204) is provided in the preheating chamber (2) at a position corresponding to the feeding furnace door (302).

6. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: The end of the flue gas conveying pipe (303) that extends into the preheating chamber (2) is provided with a smoke distribution plate (306).

7. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: The preheating inlet (202) is provided with a feeding roller conveyor (206) on the outside, and the discharge furnace door (301) is provided with a discharge roller conveyor (305) on the outside.

8. The double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: An upward extension plate (801) is provided on the side of the top of the outer vertical plate (8) away from the inner vertical plate (9), and a locking platform (802) is formed between the extension plate (801) and the top of the outer vertical plate (8).

9. A double-chamber rotary hearth furnace for zinc recovery from steelmaking dust and sludge according to claim 1, characterized in that: The heat-conducting component (6) includes a rhomboid body (601), a hollow cavity (602) is formed inside the rhomboid body (601), and extended fins (603) are provided at both ends along the long axis of the rhomboid body (601).

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