A method for preparing high-quality metallized pellets

Abstract

The present invention discloses a method for preparing high-quality metallized pellets. The method comprises the following steps: using a pelletizing machine to prepare carbon core pellets with a diameter of 2 to 3 cm from carbon powder; adding a water-soluble binder A to water to prepare a binder A solution with a concentration of 10 wt%, and spraying the solution onto the surface of the carbon core pellets to wet them; taking high-iron and low-zinc dust 7 to 10 times the mass of the carbon core, adding 1% of the binder B and 0.5% of the binder C to the high-iron and low-zinc dust, and mixing them evenly; adding the obtained carbon core pellets to a disc pelletizing machine, and then adding the obtained binder C to the pellets; The mixture and water in an amount of 10% by mass of the high-iron, low-zinc dust are rotated to form primary green balls; the binder A solution is sprayed again for wetting; medium-iron, high-zinc dust with a mass of 7 to 10 times that of the carbon core is taken, 1% by mass of the binder B and 0.5% by mass of the binder C are added to the carbon core, and the mixture is uniformly mixed; the obtained primary green balls are added to a disc ball making machine, and the obtained mixture and water in an amount of 10% by mass of the medium-iron, high-zinc dust are added to the mixture, and the mixture is rotated to form secondary green balls; and metallized pellet products are obtained after segmented heating and cooling.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste utilization, and particularly relates to a method for preparing high-quality metallized pellets. Background Art

[0002] Zinc- and iron-containing dust and sludge present a significant challenge in the resource utilization of solid waste in steel and metallurgical enterprises. Traditional direct recycling to sintering can easily lead to an increased zinc load in the blast furnace, impacting smooth operation and longevity. Centralized disposal of zinc- and iron-containing dust and sludge in a rotary hearth furnace is widely adopted by steel companies. Through high-temperature dezincification and carbon reduction, the metallized pellets achieve a certain metallization rate while significantly reducing the zinc content. Reusing the metallized pellets in the blast furnace or for sintering can alleviate the problem of increased zinc load in the blast furnace.

[0003] However, due to process limitations, the metallization rate of metallized pellets produced in a rotary hearth furnace is generally around 75%, and the dezincification rate is around 85%. At the same time, an excess of carbon must be added to ensure the reduction effect. In recent years, to reduce energy consumption, steel companies have generally adopted a strategy of smelting with a large scrap ratio. This has also led to a significant increase in the zinc content of iron-containing dust and mud from scrap steel. The dezincification rate of existing rotary hearth furnaces is difficult to meet the production requirements of blast furnaces. At the same time, due to the low metallization rate of metallized pellets, returning them to the blast furnace for reuse will result in repeated heating and repeated reduction, resulting in energy consumption and waste. In addition, although excess carbon is added to the pellets, the carbon utilization rate is not high, and a large amount of carbon element escapes in the form of CO and is discharged with the flue gas from the rotary hearth furnace, resulting in energy waste. Further optimization of the traditional rotary hearth furnace process has become an urgent issue to be addressed. Summary of the Invention

[0004] The present invention aims to provide a method for preparing high-quality metallized pellets. By optimizing the methods for adding various types of iron-containing dust and mud, the green pellet preparation method, and the high-temperature reduction process, high-quality metallized pellets with a metallization rate of more than 90% and a dezincification rate of more than 93% can be prepared, while also improving the utilization efficiency of the carbon element.

[0005] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0006] A method for preparing high-quality metallized pellets comprises the following steps:

[0007] (1) Using a pelletizer, carbon powder is prepared into carbon core pellets with a diameter of 2 to 3 cm;

[0008] (2) adding water-soluble binder A to water to prepare a binder A solution with a concentration of 10 wt%, and spraying the solution onto the surface of the carbon core pellets to wet them. The spraying amount is 4 to 8% of the mass of the carbon core pellets.

[0009] (3) Take high iron and low zinc dust sludge with a mass of 7 to 10 times that of the carbon core, add 1% of the mass of the high iron and low zinc dust sludge and 0.5% of the mass of the binder C and mix them evenly;

[0010] (4) adding the carbon core pellets obtained in step (2) into a disc pelletizing machine, and then adding the mixture obtained in step (3) and 10% water by weight of the high iron and low zinc dust, and rotating the pelletizer to form primary green pellets;

[0011] (5) spraying the binder A solution on the surface of the obtained primary green ball again to moisten it, with the spraying amount being 4-8% of the mass of the carbon core ball;

[0012] (6) Take 7 to 10 times the mass of the carbon core and add 1% of the binder B and 0.5% of the binder C to the carbon core and mix well;

[0013] (7) adding the primary green balls obtained in step (5) into a disc pelletizing machine, and then adding the mixture obtained in step (6) and water (10% by weight of the medium iron and high zinc dust) and rotating the disc pelletizing machine to form secondary green balls;

[0014] (8) The obtained secondary green balls are sent to a chain grate dryer, heated to 250-350°C, and maintained for 10-15 minutes to obtain dry balls;

[0015] (9) The dry balls are sent to a rotary hearth furnace for staged heating and reduction. The first stage is heated to 500-700°C and maintained for 3-5 minutes. The second stage is heated to 950-1050°C and maintained for 15-20 minutes. The third stage is heated to 1200-1300°C and maintained for 20-25 minutes. After cooling, the metallized pellet product is obtained.

[0016] In the above scheme, the carbon powder is a raw material obtained by grinding and drying dry dry dry dust powder, coke powder or coal powder; its chemical composition characteristics are: C ≥ 95.0%; TFe ≤ 0.5%; CaO ≤ 2.0%; MgO ≤ 0.5%; SiO2 ≤ 2.0%; Al2O3 ≤ 1.0%; K2O ≤ 0.5%; Na2O ≤ 0.5%; S ≤ 0.2%; P2O5 ≤ 0.2%; moisture ≤ 1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, and C elements, and a small amount of other unavoidable impurities; its particle size characteristics are: 200 mesh sieve residue ≤ 20.0%; 100 mesh sieve residue ≤ 5.0%.

[0017] In the above solution, the water-soluble binder A is one of starch, polyurethane, and methyl cellulose, or any mixture thereof.

[0018] In the above solution, the binder B is one of bentonite and water glass or a mixture thereof.

[0019] In the above solution, the binder C is one of phenolic resin, epoxy resin, melamine formaldehyde resin, polybutadiene resin, furan resin or any mixture thereof.

[0020] In the above scheme, the high-iron, low-zinc dust mud is a mixture of various iron-containing dust muds from steel metallurgy; its chemical composition characteristics are: 60.0%≤TFe≤70.0%; CaO≤10.0%; MgO≤5.0%; SiO2≤5.0%; Al2O3≤5.0%; K2O≤1.0%; Na2O≤1.0%; S≤0.5%; P2O5≤0.5%; Zn≤1.0%; C≤1.0%; moisture≤1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, and P elements, as well as a small amount of other unavoidable impurity elements; its particle size characteristics are: 200 mesh sieve residue ≤20.0%; 100 mesh sieve residue ≤5.0%.

[0021] In the above scheme, the medium iron and high zinc dust mud is a mixture of various iron-containing dust muds from steel metallurgy; its chemical composition characteristics are: 35.0%≤TFe≤50.0%; CaO≤20.0%; MgO≤10.0%; SiO2≤10.0%; Al2O3≤5.0%; K2O≤1.0%; Na2O≤1.0%; S≤1.0%; P2O5≤0.5%; 1.0%≤Zn≤10.0%; C≤2.0%; moisture≤1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, and P elements, and a small amount of other inevitable impurity elements; its particle size characteristics are: 200 mesh sieve residue ≤20.0%; 100 mesh sieve residue ≤5.0%.

[0022] Preferably, the heating temperature in step (8) is 300-350°C;

[0023] Preferably, in step (9), the second stage heating temperature is 1000-1050°C, and the third stage heating temperature is 1250-1300°C.

[0024] The main chemical reactions in the rotary hearth furnace process in the prior art are shown in Formulas 1 to 7.

[0025] Fe2O3 + C = 2FeO + CO (Equation 1);

[0026] FeO + C = Fe + CO (Equation 2);

[0027] ZnO + C = Zn + CO (Equation 3);

[0028] ZnO + CO = Zn + CO2 (Equation 4);

[0029] CO + Fe2O3 = 2FeO + CO2 (Equation 5);

[0030] CO + FeO = Fe + CO2 (Eq. 6);

[0031] C + CO2 = 2CO Formula 7;

[0032] Conventional rotary hearth furnace technology uses a mixture of various iron-containing dust, carbon powder, and a binder to form pellets, followed by heating and reduction for dezincification. All materials are mixed directly at once. Because the heat transfer process in the rotary hearth furnace gradually increases from the outside to the inside, materials on the outside react first, leaving those on the inside behind. This results in the zinc element inside reacting later and volatilizing through the outer materials, resulting in a long migration distance, which affects dezincification efficiency. Furthermore, the reaction between carbon and iron oxide is a solid-solid reaction, resulting in low kinetic efficiency and a negative impact on metallization. Furthermore, after being converted to CO, the carbon on the outside overflows the pellet and enters the exhaust gas, impacting its utilization.

[0033] The present invention utilizes a layered pelletizing method and optimizes the rotary hearth furnace heating system. After preheating, the pellets are heated to above 950°C in the second stage, reaching the reduction and dezincification temperature (Zn sublimation temperature). As the pellets gradually heat, the core temperature gradually increases, and the carbon core reacts with the high-iron layer, producing a large amount of CO. Because the gas-solid reaction is more efficient than the solid-solid reaction, the CO migrates outward (before leaving the pellet) and further reacts with the iron oxide / zinc oxide in the current or outer layers, converting to CO2. This significantly reduces the waste of carbon caused by CO escaping from the pellet. CO2 migrates outward and escapes with the flue gas, while CO2 migrates inward and reacts with carbon (Equation 7), converting to CO, which again possesses reducing ability. As for zinc, since most of the zinc is located in the outer layer of the pellet, which is constantly at a higher temperature, the zinc migration distance is shorter than in traditional pellets, making it easier to escape outward and achieving a higher dezincification rate. Further heating to above 1200°C makes the reduction and dezincification reaction within the pellet more intense and thorough.

[0034] In the existing metallized pellet preparation process, in order to ensure a good metallization rate and dezincification rate, the amount of C element added usually needs to account for more than 12% of the total mass of the pellet, which is excessive for the reduction demand. The present method improves the utilization efficiency of C element and reduces the amount of C element added by more than 40% compared with the existing method.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The metallized pellets obtained by the present invention have a high metallization rate and a low zinc content, and are more energy-efficient than the existing method when recycled into a blast furnace, thereby helping to reduce the zinc load of the blast furnace.

[0037] The carbon resources of the pellets of the present invention are effectively utilized, which reduces the waste caused by incomplete conversion of carbon in the conventional rotary hearth furnace method for treating iron-containing dust and mud and discharging it in the form of CO with flue gas. At the same time, the carbon content in the pellets is lower than that of the conventional method.

[0038] The present invention treats iron-containing dust and mud, thereby effectively utilizing metallurgical resources, avoiding resource waste, and protecting the environment.

[0039] The process of the present invention is simple, and only a small amount of pelletizing equipment needs to be added to the existing process, with low investment and high technical and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 : Schematic diagram of the structure of high-quality metallized pellets of the present invention.

[0041] Figure 2 : Flow chart of the process for preparing high-quality metallized pellets of the present invention. DETAILED DESCRIPTION

[0042] The following examples further illustrate the technical solutions of the present invention but are not intended to limit the scope of protection of the present invention.

[0043] The specific embodiment provides a method for preparing high-quality metallized pellets, the process flow of which is as follows: Figure 2 As shown:

[0044] (1) Using a pelletizer, carbon powder is prepared into carbon core pellets with a diameter of 2 to 3 cm;

[0045] (2) adding water-soluble binder A to water to prepare a binder A solution with a concentration of 10 wt%, and spraying the solution onto the surface of the carbon core pellets to wet them. The spraying amount is 4 to 8% of the mass of the carbon core pellets.

[0046] (3) Take high iron and low zinc dust sludge with a mass of 7 to 10 times that of the carbon core, add 1% of the mass of the high iron and low zinc dust sludge and 0.5% of the mass of the binder C and mix them evenly;

[0047] (4) adding the carbon core pellets obtained in step (2) into a disc pelletizing machine, and then adding the mixture obtained in step (3) and 10% water by weight of the high iron and low zinc dust, and rotating the pelletizer to form primary green pellets;

[0048] (5) spraying the binder A solution on the surface of the obtained primary green ball again to moisten it, with the spraying amount being 4-8% of the mass of the carbon core ball;

[0049] (6) Take 7 to 10 times the mass of the carbon core and add 1% of the binder B and 0.5% of the binder C to the carbon core and mix well;

[0050] (7) adding the primary green balls obtained in step (5) into a disc pelletizing machine, and then adding the mixture obtained in step (6) and water (10% by weight of the medium iron and high zinc dust) and rotating the disc pelletizing machine to form secondary green balls;

[0051] (8) The obtained secondary green balls are sent to a chain grate dryer, heated to 250-350°C, and maintained for 10-15 minutes to obtain dry balls;

[0052] (9) The dry balls are sent to a rotary hearth furnace for staged heating and reduction. The first stage is heated to 500-700°C and maintained for 3-5 minutes. The second stage is heated to 950-1050°C and maintained for 15-20 minutes. The third stage is heated to 1200-1300°C and maintained for 20-25 minutes. After cooling, the metallized pellet product is obtained. The structural diagram is shown in FIG. Figure 1 shown.

[0053] Specifically, the carbon powder is a raw material obtained by grinding and drying dry dry dry dust removal powder, coke powder or coal powder; its chemical composition characteristics are: C ≥ 95.0%; TFe ≤ 0.5%; CaO ≤ 2.0%; MgO ≤ 0.5%; SiO2 ≤ 2.0%; Al2O3 ≤ 1.0%; K2O ≤ 0.5%; Na2O ≤ 0.5%; S ≤ 0.2%; P2O5 ≤ 0.2%; moisture ≤ 1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, and C elements, and a small amount of other unavoidable impurity elements; its particle size characteristics are: 200 mesh sieve residue ≤ 20.0%; 100 mesh sieve residue ≤ 5.0%.

[0054] Specifically, the water-soluble binder A is one of starch, polyurethane, and methyl cellulose, or any mixture thereof.

[0055] Specifically, the binder B is one of bentonite and water glass, or a mixture thereof.

[0056] Specifically, the binder C is one of phenolic resin, epoxy resin, melamine formaldehyde resin, polybutadiene resin, furan resin, or any mixture thereof.

[0057] Specifically, the high-iron, low-zinc dust mud is a mixture of various iron-containing dust muds from steel metallurgy; its chemical composition characteristics are: 60.0%≤TFe≤70.0%; CaO≤10.0%; MgO≤5.0%; SiO2≤5.0%; Al2O3≤5.0%; K2O≤1.0%; Na2O≤1.0%; S≤0.5%; P2O5≤0.5%; Zn≤1.0%; C≤1.0%; moisture≤1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, and P elements, as well as a small amount of other inevitable impurity elements; its particle size characteristics are: 200 mesh sieve residue ≤20.0%; 100 mesh sieve residue ≤5.0%.

[0058] Specifically, the medium-iron high-zinc dust mud is a mixture of various iron-containing dust muds from steel metallurgy; its chemical composition characteristics are: 35.0%≤TFe≤50.0%; CaO≤20.0%; MgO≤10.0%; SiO2≤10.0%; Al2O3≤5.0%; K2O≤1.0%; Na2O≤1.0%; S≤1.0%; P2O5≤0.5%; 1.0%≤Zn≤10.0%; C≤2.0%; moisture≤1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, and P elements, as well as a small amount of other inevitable impurity elements; its particle size characteristics are: 200 mesh sieve residue ≤20.0%; 100 mesh sieve residue ≤5.0%.

[0059] Preferably, the heating temperature in step (8) is 300-350°C;

[0060] Preferably, in step (9), the second stage heating temperature is 1000-1050°C, and the third stage heating temperature is 1250-1300°C.

[0061] Example 1

[0062] (1) Using a pelletizer, carbon powder is prepared into small balls with a diameter of 2 to 3 cm, which serve as the carbon core of the pellets;

[0063] (2) adding 10% of water-soluble binder A to water to prepare a binder A solution, spraying the solution, which is about 4% of the mass of the carbon core, onto the surface of the carbon core pellet to wet the carbon core;

[0064] (3) Add 1% binder B and 0.5% binder C by weight of the dust mud to the high iron and low zinc dust mud of about 7 times the weight of the carbon core and mix well;

[0065] (4) adding the carbon core pellets to a disc pelletizing machine, and then adding the high iron and low zinc dust sludge mixture obtained in step (3) and 10% water by weight of the dust sludge, and rotating the pelletizer until the high iron and low zinc dust sludge is basically adhered to the surface of the carbon core to form a primary green ball;

[0066] (5) Spray the binder A solution, which is about 4% of the mass of the carbon core, on the surface of the primary green ball again to wet the primary green ball;

[0067] (6) Add 1% of the binder B and 0.5% of the binder C by weight to the medium-iron and high-zinc dust mud with a mass of about 7 times that of the carbon core and mix them evenly;

[0068] (7) adding the primary green balls to another disc pelletizing machine, and then adding the medium iron and high zinc dust sludge mixture obtained in step (6) and 10% water by weight of the dust sludge, and rotating the pelletizing machine until the low iron and high zinc dust sludge basically adheres to the surface of the primary green balls, thereby forming secondary green balls;

[0069] (8) Send the secondary green balls into a chain grate dryer, heat to 280°C, and maintain for 10 to 15 minutes to obtain dry balls;

[0070] (9) The dry balls are sent to a rotary hearth furnace for staged heating and reduction. The first stage is heated to 520°C and maintained for 3 minutes. The second stage is heated to 980°C and maintained for 15 minutes. The third stage is heated to 1220°C and maintained for 20 to 25 minutes. High-quality metallized pellets are obtained.

[0071] (10) The metallized pellets are returned to the blast furnace for use after cooling.

[0072] Example 2

[0073] A method for preparing high-quality metallized pellets comprises the following steps:

[0074] (1) Using a pelletizer, carbon powder is prepared into small balls with a diameter of 2 to 3 cm, which serve as the carbon core of the pellets;

[0075] (2) adding 10% of water-soluble binder A to water to prepare a binder A solution, spraying the solution (about 6% of the mass of the carbon core) onto the surface of the carbon core pellet to wet the carbon core;

[0076] (3) Add 1% binder B and 0.5% binder C by weight of the dust mud to the high iron and low zinc dust mud of about 8.5 times the weight of the carbon core and mix well;

[0077] (4) adding the carbon core pellets to a disc pelletizing machine, and then adding the high iron and low zinc dust sludge mixture obtained in step (3) and 10% water by weight of the dust sludge, and rotating the pelletizer until the high iron and low zinc dust sludge is basically adhered to the surface of the carbon core to form a primary green ball;

[0078] (5) Spray the binder A solution, which is about 6% of the mass of the carbon core, on the surface of the primary green ball again to wet the primary green ball;

[0079] (6) Add 1% of the binder B and 0.5% of the binder C by weight to the medium iron and high zinc dust mud with a mass of about 8.5 times the mass of the carbon core and mix them evenly;

[0080] (7) adding the primary green balls to another disc pelletizing machine, and then adding the medium iron and high zinc dust sludge mixture obtained in step (6) and 10% water by weight of the dust sludge, and rotating the pelletizing machine until the low iron and high zinc dust sludge basically adheres to the surface of the primary green balls, thereby forming secondary green balls;

[0081] (8) The secondary green balls are sent to a chain grate dryer, heated to 300°C, and maintained for 12 minutes to obtain dry balls;

[0082] (9) The dry balls are sent to a rotary hearth furnace for staged heating and reduction. The second stage is heated to 630°C and maintained for 4 minutes. The second stage is heated to 1010°C and maintained for 18 minutes. The third stage is heated to 1250°C and maintained for 23 minutes. High-quality metallized pellets are obtained.

[0083] (10) The metallized pellets are returned to the blast furnace for use after cooling.

[0084] Example 3

[0085] A method for preparing high-quality metallized pellets comprises the following steps:

[0086] (1) Using a pelletizer, carbon powder is prepared into small balls with a diameter of 2 to 3 cm, which serve as the carbon core of the pellets;

[0087] (2) adding 10% of water-soluble binder A to water to prepare a binder A solution, spraying the solution, which accounts for about 8% of the mass of the carbon core, onto the surface of the carbon core pellet to wet the carbon core;

[0088] (3) Add 1% binder B and 0.5% binder C by weight of the dust mud to the high iron and low zinc dust mud of about 10 times the weight of the carbon core and mix well;

[0089] (4) adding the carbon core pellets to a disc pelletizing machine, and then adding the high iron and low zinc dust sludge mixture obtained in step (3) and 10% water by weight of the dust sludge, and rotating the pelletizer until the high iron and low zinc dust sludge is basically adhered to the surface of the carbon core to form a primary green ball;

[0090] (5) Spray the binder A solution, which is about 8% of the mass of the carbon core, on the surface of the primary green ball again to wet the primary green ball;

[0091] (6) Add 1% of the binder B and 0.5% of the binder C by weight to the medium iron and high zinc dust mud with a mass of about 10 times that of the carbon core and mix them evenly;

[0092] (7) adding the primary green balls to another disc pelletizing machine, and then adding the medium iron and high zinc dust sludge mixture obtained in step (6) and 10% water by weight of the dust sludge, and rotating the pelletizing machine until the low iron and high zinc dust sludge basically adheres to the surface of the primary green balls, thereby forming secondary green balls;

[0093] (8) The secondary green balls are sent to a chain grate dryer, heated to 340°C, and maintained for 15 minutes to obtain dry balls;

[0094] (9) The dry balls are sent to a rotary hearth furnace for staged heating and reduction. The second stage is heated to 680°C and maintained for 5 minutes. The second stage is heated to 1050°C and maintained for 20 minutes. The third stage is heated to 1290°C and maintained for 25 minutes. High-quality metallized pellet products are obtained.

[0095] (10) The metallized pellets are returned to the blast furnace for use after cooling.

[0096] Comparative Example

[0097] Comparative Examples 1 and 2 used the same two dust and sludge materials as Example 1. The C content in the pellets of Comparative Example 1 was 6.0%, while that of the pellets of Comparative Example 2 was 12.0%. In Comparative Examples 1 and 2, all materials were mixed together before pelletizing. The thermal system followed the heating system defined in steps (8) and (9) of Example 3 (with the highest heat supply). The metallization rate and dezincification rate of the resulting metallized pellets are shown in Table 1.

[0098] C content Metallization rate Zinc removal rate Example 1 6.0％ 93.4％ 93.9％ Example 2 5.0％ 94.8％ 94.6％ Example 3 4.3％ 92.7％ 97.3％ Comparative Example 1 6.0％ 64.5％ 79.2％ Comparative Example 2 12.0％ 78.1％ 87.2％

[0099] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing high-quality metallized pellets, characterized in that The steps include: (1) Using a pelletizer, carbon powder is prepared into carbon core pellets with a diameter of 2 to 3 cm; (2) adding a water-soluble binder A to water to prepare a binder A solution with a concentration of 10 wt%, and spraying the solution onto the surface of the carbon core pellets to wet them. The spraying amount is 4 to 8% of the mass of the carbon core pellets. The water-soluble binder A is one of starch, polyurethane, and methyl cellulose, or any mixture thereof. (3) Take high iron and low zinc dust mud with a mass of 7 to 10 times that of the carbon core, add 1% of the mass of the high iron and low zinc dust mud to the binder B and 0.5% of the binder C and mix them evenly; the binder B is one of bentonite and water glass or a mixture; (4) adding the carbon core pellets obtained in step (2) into a disc pelletizing machine, and then adding the mixture obtained in step (3) and 10% water by weight of the high iron and low zinc dust, and rotating the pelletizer to form primary green pellets; (5) Spraying the binder A solution on the surface of the obtained primary green ball again to moisten it, with the spraying amount being 4-8% of the mass of the carbon core ball; (6) Take 7 to 10 times the mass of the carbon core, add 1% of the mass of the binder B and 0.5% of the binder C and mix them evenly; the binder C is one of phenolic resin, epoxy resin, melamine formaldehyde resin, polybutadiene resin, furan resin or any mixture thereof; (7) Add the primary green balls obtained in step (5) into a disc ball making machine, and then add the mixture obtained in step (6) and water (10% by weight of the medium iron high zinc dust mud), and rotate to form secondary green balls; (8) The obtained secondary green balls are sent to a chain grate dryer, heated to 250-350°C, and maintained for 10-15 minutes to obtain dry balls; (9) The dry balls are sent to a rotary hearth furnace for staged heating and reduction. The first stage is heated to 500-700°C and maintained for 3-5 minutes. The second stage is heated to 950-1050°C and maintained for 15-20 minutes. The third stage is heated to 1200-1300°C and maintained for 20-25 minutes. After cooling, the metallized pellet product is obtained.

2. The method for preparing high-quality metallized pellets according to claim 1, characterized in that The carbon powder is a raw material obtained by grinding and drying dry dry dry dust powder, coke powder or coal powder; its chemical composition characteristics are: C ≥ 95.0%; TFe ≤ 0.5%; CaO ≤ 2.0%; MgO ≤ 0.5%; SiO2 ≤ 2.0%; Al2O3 ≤ 1.0%; K2O ≤ 0.5%; Na2O ≤ 0.5%; S ≤ 0.2%; P2O5 ≤ 0.2%; moisture ≤ 1.0%; the balance is O, H, N elements combined with Fe, Zn, S, C elements, and a small amount of other unavoidable impurities. Its particle size characteristics are: 200 mesh sieve residue ≤ 20.0%; 100 mesh sieve residue ≤ 5.0%.

3. The method for preparing high-quality metallized pellets according to claim 1, characterized in that The high-iron, low-zinc dust sludge is a mixture of various iron-containing dust sludges from steel metallurgy; its chemical composition characteristics are: 60.0%≤TFe≤70.0%; CaO≤10.0%; MgO≤5.0%; SiO2≤5.0%; Al2O3≤5.0%; K2O≤1.0%; Na2O≤1.0%; S≤0.5%; P2O5≤0.5%; Zn≤1.0%; C≤1.0%; moisture≤1.0%; the balance being O, H, N elements combined with Fe, Zn, S, and P elements, and a small amount of other unavoidable impurity elements; Its particle size characteristics are: 200 mesh sieve residue ≤ 20.0%; 100 mesh sieve residue ≤ 5.0%.

4. The method for preparing high-quality metallized pellets according to claim 1, characterized in that The medium iron high zinc dust sludge is a mixture of various iron-containing dust sludges from steel metallurgy; its chemical composition characteristics are: 35.0%≤TFe≤50.0%; CaO≤20.0%; MgO≤10.0%; SiO2≤10.0%; Al2O3≤5.0%; K2O≤1.0%; Na2O≤1.0%; S≤1.0%; P2O5≤0.5%; 1.0%≤Zn≤10.0%; C≤2.0%; moisture≤1.0%; the remainder is O, H, N elements combined with Fe, Zn, S, P elements, and a small amount of other unavoidable impurity elements; Its particle size characteristics are: 200 mesh sieve residue ≤ 20.0%; 100 mesh sieve residue ≤ 5.0%.

5. The method for preparing high-quality metallized pellets according to claim 1, characterized in that The heating temperature in step (8) is 300-350°C.

6. The method for preparing high-quality metallized pellets according to claim 1, characterized in that In step (9), the second heating temperature is 1000~1050℃. The third heating temperature is 1250~1300℃.

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