A direct reduction processing device and processing method of a rotary kiln

Abstract

The application discloses a kind of direct reduction processing device and processing method of cone furnace, processing device includes for making green ball ball press, for green ball is heated and is reduced to form mature ball cone furnace, the cone furnace includes cone disc and is set above cone disc cone cover, material drop chute for receiving green ball is opened on cone cover;Conical disc below is used to drive driving mechanism for driving conical disc rotation;Along the circumferential direction of conical disc, at the matching surface of conical disc and cone cover, discharge chute is set, rotary discharger is set in discharge chute, mature ball tank for receiving mature ball is set correspondingly at the outlet end of discharge chute;The present application can realize the efficient environmental protection direct reduction processing of metal ore powder and metallurgical solid waste.The method process is simple, and the equipment difficulty is relatively low, and the resource recovery value is large, compared with traditional direct reduction process has the advantages of small floor area, high energy utilization rate, good environmental benefits, low system cost and the like.

Description

Technical Field

[0001] This invention relates to the field of metallurgical solid waste treatment technology, specifically to a direct reduction treatment device and method using a rotary cone furnace. Background Technology

[0002] Direct reduction (DR) technology boasts advantages such as low system investment, small footprint, and low energy consumption, making it widely used in the steel and ferroalloy industries. Specifically, it is used in direct reduction ironmaking to produce cold-pressed briquettes for use in electric arc furnaces; in nickel-iron production, rotary kiln direct reduction pellets are used as raw materials for submerged arc furnace melting; and zinc-containing dust and sludge are directly reduced to produce metallized pellets followed by dezincification treatment. Therefore, DR technology has broad applications in the reduction treatment of metal ore powders and the resource utilization of metallurgical solid waste.

[0003] Currently, the two main types of mature direct reduction equipment are rotary kilns and rotary hearth furnaces. Rotary kilns offer the advantage of low investment and are widely used in direct reduction of iron cold briquettes, preheating of nickel-iron ore powder for direct reduction, and dezincification of zinc-containing dust and sludge. Rotary hearth furnaces are primarily used in the dezincification of zinc-containing dust and sludge in steel enterprises.

[0004] Rotary kiln technology is widely used due to its low investment and operating costs. However, it is undeniable that rotary kiln technology generally suffers from problems such as small processing scale, low metal element reduction rate, kiln ring formation, and poor production environment. In comparison, rotary hearth furnace technology has advantages such as large processing scale, high metal element reduction and recovery rate, and a better production environment. However, rotary hearth furnace technology suffers from problems such as low energy utilization, large system equipment, high investment and operating costs, and poor economic benefits because it processes only one layer of green pellets, the material layer is too thin, and the effective bed area is only a ring area. Summary of the Invention

[0005] Technical objective: To address the shortcomings of existing reduction processes, this invention discloses a direct reduction treatment device and method for a rotary cone furnace that effectively reduces metal curing metals, effectively separates and recovers low-melting-point metals, improves energy utilization, and reduces costs.

[0006] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A rotary cone furnace direct reduction processing apparatus includes a briquetting machine for making green pellets and a rotary cone furnace for heating and reducing green pellets into mature pellets. The rotary cone furnace includes a cone disk and a cone cover disposed above the cone disk. A material discharge chute for receiving green pellets is provided on the cone cover. A drive mechanism for rotating the cone disk is provided below the cone disk. A discharge chute is provided at the mating surface between the cone disk and the cone cover along the circumferential direction of the cone disk. A rotary discharger is provided in the discharge chute. A mature pellet tank for receiving mature pellets is provided at the outlet end of the discharge chute.

[0008] Preferably, a base plate is provided below the cone disk of the present invention, the cone disk is fixed on the base plate, and the edge of the base plate and the lower edge of the cone cover are sealed by a water seal groove, so that a closed calcination space is formed between the cone disk and the cone cover. A burner is provided on the side of the cone cover near the surface of the cone disk, and the burners are arranged concentrically according to the cone center of the cone cover.

[0009] Preferably, the drive mechanism of the present invention includes a rotating shaft concentrically mounted on the chassis and fixedly connected at one end to the conical disk. The end of the rotating shaft opposite to the conical disk is rotatably connected to a base provided at the bottom for support. A rotating wheel is provided at the bottom of the chassis, and the rotating wheels are evenly distributed along the surface of the chassis. The rotation shaft of some of the rotating wheels is connected to a motor, and the rotating wheels are driven by the motor to rotate, thereby driving the chassis and the conical disk to rotate.

[0010] Preferably, the upper part of the cone shroud of the present invention has a flue, and the end of the flue is sequentially connected to a heat exchanger for treating flue gas, a gravity settling chamber, a bag filter, an induced draft fan and a chimney.

[0011] Preferably, the briquetting machine of the present invention is connected to the silo, which includes a raw material silo, a reducing agent silo, and a binder silo. A weighing belt and a feeder for weighing and feeding the corresponding materials are provided below the silo.

[0012] Preferably, a roasting machine for roasting and shaping green pellets is provided between the pellet press and the rotary cone furnace of the present invention, and the green pellets enter the rotary cone furnace after roasting.

[0013] This invention discloses a direct reduction process in a rotating cone furnace, using the aforementioned processing apparatus, comprising the following steps:

[0014] S01. The mixed raw materials are rolled into green balls by a briquetting machine;

[0015] S02. The green balls enter the surface of the cone disc from the feed chute on the cone cover and descend along the inclined surface of the cone disc to form a material layer on the surface of the cone disc;

[0016] S03. During the downward movement of the green pellets, the drive mechanism drives the cone disk to rotate. The burner inside the cone shroud heats and reduces the green pellets, and the metal oxides inside the green pellets are reduced to elemental metals by the reducing agent. The flue gas generated by heating is discharged through the flue on the cone shroud. The rotating discharge device at the bottom of the cone disk pushes the reduced cooked pellets from the discharge chute into the cooked pellet tank.

[0017] Preferably, in step S02 of the present invention, the green pellets are preheated in a roasting machine before entering the cone hood to increase the temperature of the green pellets and remove the moisture inside the green pellets.

[0018] Preferably, in step S03 of the present invention, when the metal oxide inside the green pellet is reduced, the low-melting-point metal volatilizes under high temperature and enters the flue with the flue gas. The heat exchanger connected to the flue gas absorbs the heat of the flue gas, reduces the flue gas temperature, and causes the metal to re-solidify. The metal dust is then recovered through the gravity settling chamber and bag filter at the rear end of the flue gas.

[0019] Preferably, in step S01 of the present invention, the content of reducing agent in the mixed raw materials is 0-20%, and the content of binder is 1-5%. The raw materials, reducing agent, and binder are mixed with water and then fed into the briquetting machine. The amount of water added is not more than 10% of the total amount of the mixed raw materials.

[0020] Beneficial effects: The direct reduction treatment device and method for a rotating cone furnace disclosed in this invention have the following beneficial effects:

[0021] 1. In this invention, green pellets produced by a briquetting machine are heated and reduced in a rotary cone furnace. The conical structure of the rotary cone furnace can reduce the space occupied by the equipment. At the same time, green pellets can be stacked in several layers along the surface of the cone, thereby improving production efficiency and energy utilization.

[0022] 2. The cone surface of the rotary cone furnace of the present invention is a sloping structure. After the green balls enter, they can automatically descend and collect at the edge of the cone under the action of gravity. On the one hand, the heated and reduced cooked balls can be moved to the discharge end without the need for power, thereby reducing equipment costs. On the other hand, the green balls are rotated by the cone, and are heated by the burners set on the cone shroud during the downward movement of the green balls, which can ensure the uniformity of heating and reduction and control the heating time.

[0023] 3. The present invention has a base plate for support below the cone plate, and the cone plate is driven to rotate by the rotating wheel below the base plate, which can improve the stability of the rotation process and ensure the heating effect on the green balls.

[0024] 4. The present invention sets up a flue above the cone cover, and sets up a heat exchanger, a gravity settling chamber and a bag filter along the flue gas flow direction. The flue gas is cooled by the heat exchanger, so that the evaporated low melting point metal is cooled and condensed into solid metal powder, which can be settled and recovered, thereby achieving efficient separation and recovery of low melting point metals such as zinc and lead in the raw materials.

[0025] 5. The present invention is equipped with a weighing belt and a feeder below the hopper, which can control the proportion of mixed raw materials, thereby ensuring the strength of green pellets and preventing loosening during subsequent heating and reduction processes, which would affect the reduction process.

[0026] 6. The present invention is equipped with a roasting machine. Before the green pellets are heated and reduced, they are roasted to remove moisture and increase the strength of the green pellets, which is beneficial to the subsequent heating and reduction in the rotary cone furnace. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0028] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention;

[0029] Among them, 1-green pellets, 2-pellet press, 3-roasting machine, 4-rotary cone furnace, 5-cone plate, 6-cone hood, 7-feeding chute, 8-discharge chute, 9-rotary discharger, 10-cooked pellet tank, 11-chassis, 12-water seal trough, 13-burner, 14-shaft, 15-base, 16-rotor, 17-flue, 18-heat exchanger, 19-gravity settling chamber, 20-bag filter, 21-induced draft fan, 22-chimney, 23-raw material silo, 24-reducing agent silo, 25-binder silo. Detailed Implementation

[0030] The present invention will now be described more clearly and completely by way of a preferred embodiment in conjunction with the accompanying drawings, but this does not limit the invention to the scope of the described embodiment.

[0031] like Figure 1 The diagram shows a direct reduction processing apparatus for a rotary cone furnace provided by the present invention, comprising a briquetting machine 2 for making green balls 1 and a rotary cone furnace 4 for heating and reducing green balls 1 to form mature balls. The rotary cone furnace 4 includes a cone disk 5 and a cone cover 6 disposed above the cone disk 5. A material discharge chute 7 for receiving green balls 1 is provided on the cone cover 6. A drive mechanism for rotating the cone disk 5 is provided below the cone disk 5. A discharge chute 8 is provided at the mating surface between the cone disk 5 and the cone cover 6 along the circumferential direction of the cone disk 5. A rotary discharger 9 is provided in the discharge chute 8. A mature ball tank 10 for receiving mature balls is provided at the outlet end of the discharge chute 8.

[0032] The briquetting machine 2 is connected to the silo, which includes a raw material silo 23, a reducing agent silo 24, and a binder silo 25. Weighing belts and feeders for weighing and feeding the corresponding materials are installed below each silo. In this embodiment, the raw material silo 23, reducing agent silo 24, and binder silo 25 are steel or concrete structures, and the volume of the raw material silo 23 is not less than 20 m³. 3 The volume of both the reducing agent chamber 24 and the binder chamber 25 is not less than 5m³. 3 The reducing agent is added at 0-20%, the binder at 1-5%, and the water added during the batching process does not exceed 10%. All the above proportions are mass fractions. The briquetting machine 2 is a high-pressure double-roller briquetting machine with a production pressure of 150-600t and a zinc dust and sludge processing capacity of 5-50 / h. It produces green briquettes 1 with a particle size of 10-50mm. The strength of the green briquettes 1 produced by the briquetting machine 2 is 800-1500N / ball, and the strength after a 2m drop is not less than 5 times. To ensure the strength of the green briquettes and prevent them from scattering during the heating and reduction process, a calcining machine 3 is set between the briquetting machine 2 and the rotating cone furnace 4 for calcining and shaping the green briquettes 1. After calcination, the green briquettes 1 enter the rotating cone furnace 4. During the calcination process, the moisture in the green briquettes 1 is dried and removed, and the strength of the green briquettes 1 is improved as the temperature increases.

[0033] To ensure stable rotation of the conical disc and improve heating uniformity, a base plate 11 is provided below the conical disc 5. The conical disc 5 is fixed on the base plate 11, and the edge of the base plate 11 is sealed to the lower edge of the conical cover 6 by a water seal groove 12, forming a closed calcination space between the conical disc 5 and the conical cover 6. In this embodiment, the water seal groove 12 is a steel structure annular water tank with a steel plate thickness of not less than 8 mm, a width of 10-30 mm, and a depth of not less than 20 mm. A burner 13 is provided on the side of the conical cover 6 near the surface of the conical disc 5, and the burners 13 are arranged concentrically with respect to the conical center of the conical cover 6.

[0034] The drive mechanism includes a rotating shaft 14 concentrically mounted on the chassis 11 and fixedly connected at one end to the conical disk 5. The end of the rotating shaft 14 facing away from the conical disk 5 is rotatably connected to a base 15 provided at the bottom for support. A rotating wheel 16 is provided at the bottom of the chassis 11. The rotating wheels 16 are evenly distributed along the surface of the chassis 11. The rotation shaft of some of the rotating wheels 16 is connected to a motor. The rotating wheels 16 are driven by the motor to rotate, thereby driving the chassis 11 and the conical disk 5 to rotate.

[0035] After the green pellets 1 enter the rotary cone furnace from the feed chute 7, they will descend along the inclined surface of the cone disk 5 under the action of gravity. Since the cone disk 5 will rotate relative to the cone cover 6 under the drive of the rotary wheel 16, the green pellets in different cone areas of the cone disk can be heated and reduced, ensuring the uniformity of heating.

[0036] To facilitate control of the heating process and ensure the quality of heating and reduction, the cone disk 5 and cone shroud 6 of this invention are arranged in parallel, forming a channel for the green balls to descend between their surfaces. The distance between the cone disk 5 and cone shroud 6 is 1-2m, the inclination angle of the cone disk 5 is 25-45°, and the thickness of the material layer formed between them is 1-5 times the height of the green balls. The average downward speed of the material layer along the slope of the cone disk 5 is 0.2-1.5m / min. The burner 13 is a gas burner, installed by inserting it from the outside of the cone shroud 6 into the inside. Two burners 13 are evenly installed around the outside of the cone shroud 6. The furnace has 4 rings, with a spacing of 0.5~5m between two adjacent burners 13. The burners 13 use high-calorific-value fuels such as natural gas and coke oven gas. The base 11 is a steel structure disc support. The cone 5 rotates around the shaft 14 on the base 11 with the rotating wheel 16. The rotation speed of the cone 5 is 5~60 minutes / revolution. Both the cone 5 and the cone cover 6 are conical steel structures. The main steel plate of the cone 5 is not less than 20mm thick, and the main steel plate of the cone cover 6 is not less than 10mm thick. Refractory material is installed on one side of the steel plate inside the rotating cone furnace 4. The thickness of the refractory material is not less than 200mm.

[0037] The low-melting-point metals contained in the raw materials are mainly non-ferrous metal elements such as zinc and lead. When heated and reduced, metal vapors are formed and discharged with the combustion flue gas. In order to achieve effective separation and recovery of low-melting-point metals, a flue 17 is opened on the upper part of the cone shroud 6 of the present invention. The end of the flue 17 is connected in sequence to a heat exchanger 18 for treating the flue gas, a gravity settling chamber 19, a bag filter 20, an induced draft fan 21, and a chimney 22. The flue gas is cooled by the heat exchanger 18, and the low-melting-point metals are gradually cooled and condensed into solid powder. They are then recovered by the gravity settling chamber 19 and the bag filter 20 at the rear end, so as to achieve efficient separation and recovery of low-melting-point metals.

[0038] This invention also discloses a direct reduction process in a rotary cone furnace, using the aforementioned processing apparatus, comprising the following steps:

[0039] S01. The mixed raw materials are rolled into green balls by a briquetting machine;

[0040] The reducing agent content in the mixed raw materials is 0-20%, and the binder content is 1-5%. After mixing the raw materials, reducing agent, and binder with water, the mixture is sent into the briquetting machine. The amount of water added should not exceed 10% of the total amount of the mixed raw materials.

[0041] S02. The green balls enter the surface of the cone disc from the feed chute on the cone cover and descend along the inclined surface of the cone disc to form a material layer on the surface of the cone disc;

[0042] To improve the strength of the green pellets entering the cone, the green pellets are preheated in a roasting machine before entering the cone shroud. This increases the temperature of the green pellets and removes moisture. The roasting temperature is not lower than 300℃, preferably 400~600℃, and the roasting cycle is 10~40 minutes. After roasting, the green pellets fall to the top of the cone shroud 5 and, under the action of gravity, descend along the slope of the cone shroud to form a material layer.

[0043] S03. During the downward movement of the green pellets, the drive mechanism drives the cone disk to rotate. The burner inside the cone shroud heats and reduces the green pellets. The processing cycle is 20-50 minutes. The high-temperature smelting temperature corresponding to the burner in the rotating cone furnace 4 is 1000-1400℃. The excess air coefficient of the combustion gas in the rotating cone furnace 4 does not exceed 1.1. The metal oxides in the green pellets are reduced to elemental metals by the reducing agent. The flue gas generated by heating is discharged through the flue on the cone shroud. The rotating discharge device at the bottom of the cone disk pushes the reduced cooked pellets from the discharge chute into the cooked pellet tank.

[0044] The rotary discharger is driven by a motor, with an outer diameter of 0.5~3m. The main structure is made of high-temperature heat-resistant steel, and the rotation speed is 5~60 revolutions per minute. It pushes the molten balls at the bottom of the cone disc into the discharge trough 8, and then into the molten ball tank 10 through the discharge trough. The molten ball tank 10 is a steel structure tank with refractory insulation material inside. The refractory material thickness is not less than 100mm. A sealed cover is installed on the top, and nitrogen is introduced into the inside to prevent oxidation.

[0045] When the metal oxide inside the green pellet is heated and reduced, the low-melting-point metal volatilizes under high temperature and enters the flue gas. A heat exchanger connected to the flue gas absorbs the heat from the flue gas. The high-temperature flue gas discharged after passing through the heat exchanger has a temperature not exceeding 600℃, thus lowering the flue gas temperature and allowing the metal to re-solidify. Metal dust is then recovered through a gravity settling chamber and a bag filter at the rear of the flue gas. After treatment in the gravity settling chamber 19, the temperature does not exceed 150℃, and after treatment by the bag filter 20, the dust concentration in the discharged flue gas does not exceed 10 mg / m³. 3 .

[0046] Through the reduction process of the present invention, the metallization rate of the obtained molten pellets is 60-90%, and the reduction recovery rate of low melting point metal oxides such as zinc and lead exceeds 90%, and the non-ferrous metal content of the recovered low melting point metal dust is not less than 40%.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A direct reduction treatment apparatus for a rotating cone furnace, characterized in that, The equipment includes a briquetting machine (2) for making green balls (1) and a rotary cone furnace (4) for heating and reducing green balls (1) to form mature balls. The rotary cone furnace (4) includes a cone disk (5) and a cone cover (6) set above the cone disk (5). A material drop chute (7) for receiving green balls (1) is opened on the cone cover (6). A drive mechanism for rotating the cone disk (5) is set below the cone disk (5). A discharge chute (8) is set at the mating surface of the cone disk (5) and the cone cover (6) along the circumferential direction of the cone disk (5). A rotary discharger (9) is set in the discharge chute (8). A mature ball tank (10) for receiving mature balls is set at the outlet end of the discharge chute (8). A base plate (11) is provided below the cone plate (5). The cone plate (5) is fixed on the base plate (11). The edge of the base plate (11) and the lower edge of the cone cover (6) are sealed by a water seal groove (12) to form a closed calcination space between the cone plate (5) and the cone cover (6). A burner (13) is provided on the side of the cone cover (6) near the surface of the cone plate (5). The burners (13) are arranged concentrically according to the cone center of the cone cover (6).

2. The direct reduction treatment apparatus for a rotating cone furnace according to claim 1, characterized in that, The drive mechanism includes a rotating shaft (14) that is concentrically mounted on the chassis (11) and whose end is fixedly connected to the conical disk (5). The end of the rotating shaft (14) away from the conical disk (5) is rotatably connected to a base (15) provided at the bottom for support. A rotating wheel (16) is provided at the bottom of the chassis (11). The rotating wheels (16) are evenly distributed along the surface of the chassis (11). The rotation shaft of some of the rotating wheels (16) is connected to a motor. The rotating wheels (16) are driven by the motor to rotate, thereby driving the chassis (11) and the conical disk (5) to rotate.

3. The direct reduction treatment apparatus for a rotating cone furnace according to claim 1, characterized in that, The upper part of the cone shroud (6) has a flue (17), and the end of the flue (17) is connected in sequence to a heat exchanger (18), a gravity settling chamber (19), a bag filter (20), an induced draft fan (21) and a chimney (22) for treating flue gas.

4. The direct reduction treatment apparatus for a rotating cone furnace according to claim 1, characterized in that, The briquetting machine (2) is connected to the silo, which includes a raw material silo (23), a reducing agent silo (24), and a binder silo (25). Weighing belts and feeders for weighing and feeding the corresponding materials are provided below the silo.

5. The direct reduction treatment apparatus for a rotating cone furnace according to claim 1, characterized in that, A roasting machine (3) is provided between the briquetting machine (2) and the rotating cone furnace (4) for roasting and shaping the green balls (1). After roasting, the green balls (1) enter the rotating cone furnace (4).

6. A method for direct reduction treatment in a rotating cone furnace, using the treatment apparatus according to any one of claims 1-5, characterized in that, Including the following steps: S01. The mixed raw materials are rolled into green balls by a briquetting machine; S02. The green balls enter the surface of the cone disc from the feed chute on the cone cover and descend along the inclined surface of the cone disc to form a material layer on the surface of the cone disc; S03. During the downward movement of the green pellets, the drive mechanism drives the cone disk to rotate. The burner inside the cone shroud heats and reduces the green pellets, and the metal oxides inside the green pellets are reduced to elemental metals by the reducing agent. The flue gas generated by heating is discharged through the flue on the cone shroud. The rotating discharge device at the bottom of the cone disk pushes the reduced cooked pellets from the discharge chute into the cooked pellet tank.

7. The direct reduction treatment method in a rotating cone furnace according to claim 6, characterized in that, In step S02, the green pellets are preheated in the roasting machine before entering the cone hood to increase the temperature of the green pellets and remove moisture from them.

8. The direct reduction treatment method in a rotating cone furnace according to claim 6, characterized in that, During the reduction of metal oxides inside the green pellets in step S03, the low-melting-point metal volatilizes under high temperature and enters the flue with the flue gas. The heat exchanger connected to the flue gas absorbs the heat of the flue gas, reduces the flue gas temperature, and causes the metal to re-solidify. The metal dust is then recovered through the gravity settling chamber and bag filter at the rear end of the flue gas.

9. The direct reduction treatment method in a rotating cone furnace according to claim 6, characterized in that, In step S01, the reducing agent content in the mixed raw materials is 0-20%, and the binder content is 1-5%. The raw materials, reducing agent, and binder are mixed with water and then fed into the briquetting machine. The amount of water added is no more than 10% of the total amount of the mixed raw materials.

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