Method and system for hot charging and hot using of metallized pellets in rotary hearth furnace

Abstract

The invention provides a hot charging and hot using method and system for metallized pellets of a rotary hearth furnace, and relates to the field of metallurgical solid waste treatment. The method comprises the steps that a steelmaking closed slag ladle with a cover is adopted to receive hot-state metallized pellets according to a preset proportion, and closed heat preservation is conducted; sequentially adding a carbon-containing material and hot-state steel slag into the steel-making closed slag ladle with the cover, which is filled with the hot-state metallized pellets, and then carrying out closed heat preservation treatment on the steel-making closed slag ladle with the cover; after the closed heat preservation treatment reaches a preset time, all materials in the steel-making closed slag ladle with the cover are poured into a slag braising pool to be subjected to slag braising treatment; and after slag braising treatment is finished, recovering slag steel and magnetic separation powder through rod milling magnetic separation. The invention provides a new way for hot charging and hot using of the metallized pellets of the rotary hearth furnace, and the metallized pellets are further reduced to recover slag steel by adding the carbon-containing materials and residual carbon of the metallized pellets. And meanwhile, waste heat of the metallized pellets and sensible heat of the steel slag are utilized, and energy waste is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical solid waste treatment, and in particular to a method and system for hot charging and using metallized pellets in a rotary hearth furnace. Background Art

[0002] The rotary hearth furnace process is a typical direct reduction process currently used by major domestic steel mills to treat solid waste. Solid waste is reduced through a series of processes such as "raw material pretreatment - batching - strong mixing - pelletizing - direct reduction in a rotary hearth furnace" to obtain metallized pellets. Zinc oxide powder is also recovered through a dust removal system. It has been found in applications that the metallized pellets produced by the pelletizing process have lower strength, are more prone to pulverization, and contain higher levels of residual zinc than those produced by the briquetting process. Therefore, the rational use of the metallized pellets produced by the pelletizing process has become a major issue. In addition, the discharge temperature of the metallized pellets is usually around 100°C. After the metallized pellets are obtained by pelletizing in a rotary hearth furnace, they need to be cooled to meet the discharge requirements, resulting in significant energy waste.

[0003] Prior art, such as patent CN115125359B, discloses a method for hot charging and hot transporting metallized pellets from a rotary hearth furnace back to a rotary furnace for steelmaking. This method utilizes a covered pellet tank to achieve hot transport and hot charging of the metallized pellets in a hot, sealed, non-oxidizing state, and then transports them to a torpedo tank at a molten steel pretreatment station. This allows a large amount of sensible heat from the hot pellets to be directly returned to the main steelmaking process, thereby improving the efficiency of pellet waste heat utilization. However, direct use of the metallized pellets in steelmaking suffers from disadvantages such as low iron recovery in the pellets and the generation of foamy slag during the smelting process. Another example is patent CN101775488B, which discloses a method for transporting hot metallized pellets from a rotary hearth furnace using a non-resonant vibration method. This method utilizes a continuous non-resonant vibration device to transport the hot metallized pellets, which are then transported in a step-by-step manner into an electric arc furnace. The transportation of the metallized pellets is synchronized with the production of the rotary hearth furnace and electric arc furnace. However, recycling the metallized pellets into the electric arc furnace also suffers from problems such as the generation of foamy slag and low metal recovery.

[0004] Therefore, it is necessary to propose an application method of metallized pellets in a rotary hearth furnace, which can fully utilize the waste heat of the metallized pellets while reducing the generation of foamed slag and ensuring the metal recovery rate. Summary of the Invention

[0005] The object of the present invention is to provide a method and system for hot charging and hot use of metallized pellets in a rotary hearth furnace, wherein the hot metallized pellets are directly added to a steelmaking slag ladle, and the metallized pellets are dissolved and further reduced by utilizing the waste heat of the metallized pellets and the sensible heat of the hot slag. The metallized pellets are then subjected to hot stewing-rod grinding-magnetic separation, and slag steel and magnetic separation powder are recovered, thereby effectively reducing energy waste.

[0006] To achieve the above objectives, the present invention proposes the following technical solutions:

[0007] In a first aspect, a method for hot charging and hot use of metallized pellets in a rotary hearth furnace is proposed, comprising the following steps:

[0008] 1) Use a steelmaking covered closed slag ladle to receive hot metallized pellets in a preset proportion and seal and keep warm;

[0009] 2) adding carbon-containing materials and hot steel slag into a steelmaking covered sealed slag ladle containing hot metallized pellets in sequence, and then performing a sealing and heat preservation treatment on the steelmaking covered sealed slag ladle;

[0010] 3) After the sealed heat preservation treatment reaches the preset time, all the materials in the sealed slag bag with a cover are poured into the slag stewing tank for slag stewing treatment;

[0011] 4) After the slag treatment is completed, the slag steel and magnetic separation powder are recovered by rod mill magnetic separation.

[0012] Furthermore, the specific process of using a steelmaking covered closed slag ladle to receive hot metallized pellets according to a preset ratio is as follows:

[0013] Determine the maximum mass of hot slag that can be added based on the capacity of the steelmaking covered closed slag ladle;

[0014] The maximum mass of the hot metallized pellets to be received from the steelmaking closed slag ladle with a lid is determined based on the maximum mass of the hot steel slag; wherein the mass ratio of the hot metallized pellets to the hot steel slag in the steelmaking closed slag ladle with a lid shall not exceed 0.2.

[0015] Furthermore, when adding carbonaceous materials into the steelmaking closed slag ladle with a cover containing hot metallized pellets, the temperature of the hot metallized pellets in the steelmaking closed slag ladle with a cover is not lower than 700°C.

[0016] Furthermore, the carbon content of the carbon-containing material is not less than 80%.

[0017] Furthermore, the mass of the hot metallized pellets collected by the covered closed slag ladle for steelmaking is defined as Q1, and the mass of the carbon-containing material added subsequently is defined as Q2, then Q2 = (Q1 / w)*C; wherein w represents the carbon content of the carbon-containing material, and C represents a constant, which is 5% to 8%.

[0018] Furthermore, the particle size of the carbon-containing material is D, and D≤0.3 mm.

[0019] Furthermore, the preset time for the sealed insulation treatment of the steelmaking covered slag ladle is 5 to 10 minutes.

[0020] Furthermore, the carbon-containing material is selected from one or more of coke powder, coking dust ash, and anthracite.

[0021] Furthermore, the recovery rate of iron in the metallized pellets by the method for hot charging and hot use of the metallized pellets in the rotary hearth furnace is 55-75%.

[0022] In a second aspect, a system for the hot charging and hot use method of metallized pellets in a rotary hearth furnace is provided, comprising a rotary hearth furnace, a spiral discharger, a guide chute, a cooling drum, a dust removal protective cover, a steelmaking belt-covered sealed slag ladle, a guide pipe, and a slag pool; the spiral discharger is located at the bottom of the rotary hearth furnace and is used for discharging the rotary hearth furnace; one end of the guide chute is located at the discharge end of the spiral discharger, and the other end is connected in sequence to the guide pipe and the cooling drum, and is used for conveying the discharge of the rotary hearth furnace in two ways; the steelmaking belt-covered sealed slag ladle is located at the discharge end of the guide pipe, and the dust removal protective cover is sleeved between the discharge end of the guide pipe and the outer side of the steelmaking belt-covered sealed slag ladle;

[0023] The steelmaking covered closed slag ladle is first placed at the discharge end of the guide pipe to receive the hot metallized pellets discharged from the rotary hearth furnace, and is sealed and insulated; then it is transported to the steelmaking slag outlet, and carbon-containing materials are added to the steelmaking covered closed slag ladle containing the hot metallized pellets before slag discharge, and then the slag is discharged to receive the hot steel slag and is sealed and insulated for treatment; finally, the completely sealed and insulated steelmaking covered closed slag ladle is transported to the front of the slag stewing pool, poured into the slag stewing pool for slag stewing treatment, and the slag is recovered by rod mill magnetic separation and magnetic separation.

[0024] It can be seen from the above technical solutions that the technical solutions of the present invention have the following beneficial effects:

[0025] The present invention discloses a method and system for hot charging and using metallized pellets in a rotary hearth furnace, the method comprising: using a steelmaking covered sealed slag ladle to receive hot metallized pellets in a preset proportion, and sealing and insulating the hot metallized pellets; sequentially adding carbon-containing materials and hot steel slag to the steelmaking covered sealed slag ladle containing the hot metallized pellets, and then sealing and insulating the steelmaking covered sealed slag ladle; after the sealed and insulating treatment reaches a preset time, pouring all the materials in the steelmaking covered sealed slag ladle into a slag stewing pool for slag stewing treatment; after the slag stewing treatment is completed, recovering slag steel and magnetic separation powder through rod mill magnetic separation. In order to solve the problem of the narrow use of metallized pellets, the present invention has developed a new way to hot charge and use metallized pellets in a rotary hearth furnace; specifically, directly adding hot metallized pellets to the steelmaking slag ladle, making full use of the waste heat of the metallized pellets and the sensible heat of the steel slag, and further reducing the metallized pellets and recovering the slag steel by adding carbon-containing materials and the residual carbon of the metallized pellets themselves.

[0026] Compared to the existing technology that generates foamy slag and low metal recovery rates when recycling rotary hearth furnace metallized pellets in electric furnaces and converters, this method, by adjusting the amount, temperature, and reaction time of adding rotary hearth furnace metallized pellets to the steelmaking slag ladle, avoids the formation of foamy slag and effectively improves metal recovery efficiency. Furthermore, by directly utilizing the waste heat of the metallized pellets and the sensible heat of the slag, it effectively reduces energy waste, improves the efficiency of metallized pellet production, and improves the overall energy conversion efficiency of steelmaking.

[0027] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the inventive subject matter of this disclosure.

[0028] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or through practice of specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0030] Figure 1 This is a flow chart of the method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to the present invention;

[0031] Figure 2 It is a schematic diagram of hot charging of hot metallized pellets into a steelmaking covered and sealed slag ladle according to the present invention.

[0032] In the figure, the specific meaning of each mark is:

[0033] 1-rotary hearth furnace, 2-screw discharger, 3-material guide chute, 4-cooling cylinder, 5-dust removal protection cover, 6-steelmaking closed slag ladle with cover, 7-material guide pipe. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0035] The words “first”, “second” and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of “a”, “an” or “the” and similar words do not indicate a quantity limitation, but rather indicate the presence of at least one. Words such as “include” or “comprise” mean that the elements or objects appearing before “include” or “comprises” cover the features, wholes, steps, operations, elements and / or components listed after “include” or “comprises”, and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. “Up”, “down”, “left”, “right” and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0036] Due to the defects of the metallized pellets produced by the rotary hearth furnace pelletizing process, they cannot be directly added to the blast furnace for use, and there are problems such as the generation of foamed slag and low metal recovery rate during reuse in electric furnaces and converters, resulting in low utilization efficiency of the existing metallized pellets and waste of sensible heat. Therefore, the present invention aims to propose a method and system for hot charging and hot use of metallized pellets in a rotary hearth furnace, in which the hot metallized pellets are directly added to a steelmaking slag ladle, and the slag iron is recovered from the metallized pellets by adding a reducing agent and utilizing the sensible heat of the metallized pellets and the sensible heat of the hot steel slag.

[0037] Specific as Figure 1 As shown, the method for hot charging and hot use of metallized pellets in a rotary hearth furnace comprises the following steps:

[0038] 1) Use a steelmaking covered closed slag ladle to receive hot metallized pellets in a preset proportion and seal and keep warm;

[0039] 2) adding carbon-containing materials and hot steel slag to a covered closed slag ladle containing hot metallized pellets in sequence, and then sealing and insulating the covered closed slag ladle; in order to prevent the slag from cooling into a solid state during subsequent slag tapping and affecting the reaction effect, the temperature of the hot metallized pellets in the covered closed slag ladle is not less than 700° C. when adding the carbon-containing materials to the covered closed slag ladle containing hot metallized pellets;

[0040] 3) After the sealed heat preservation treatment reaches the preset time, all the materials in the sealed slag bag with a cover are poured into the slag stewing tank for slag stewing treatment;

[0041] 4) After the slag treatment is completed, the slag steel and magnetic separation powder are recovered by rod mill magnetic separation;

[0042] In the above flow, the specific process of using the steelmaking closed slag ladle with a cover to receive the hot metallized pellets in a preset proportion is as follows: based on the capacity of the steelmaking closed slag ladle with a cover, the maximum mass of the hot steel slag that can be added is determined; based on the maximum mass of the hot steel slag, the maximum mass of the hot metallized pellets to be received in the steelmaking closed slag ladle with a cover is determined; among which, the mass ratio of the hot metallized pellets to the hot steel slag in the steelmaking closed slag ladle with a cover does not exceed 0.2. Excessive hot metallized pellets will result in insufficient reaction, which will not only reduce the iron recovery rate but also cause the hot steel slag to solidify prematurely.

[0043] The purpose of adding carbon-containing materials to the steelmaking covered closed slag ladle containing hot metallized pellets is to further reduce the metallized pellets; the amount of carbon source added is determined by the ratio of the unreduced iron content in the metallized pellets to the carbon content in the carbon source; theoretically, when the C / Fe (Fe is the unreduced iron in the metallized pellets) content ratio in the mixture is not less than 1, all the unreduced iron in the metallized pellets can be reduced, but due to the dynamic equilibrium conditions of the reaction, it is impossible to completely reduce all the unreduced iron in the metallized pellets, and due to economic costs, the economic benefit of reducing the unreduced Fe in the metallized pellets can be maximized when the C / Fe content ratio is controlled at 0.5-0.7. ; Further increasing the content of carbon-containing materials does not significantly increase the reduction ratio of unreduced Fe, and the amount of carbon-containing materials added must far exceed the increase in the reduction ratio of the Fe element, which reduces the economic efficiency; In this case, the carbon content of the selected carbon-containing materials is not less than 80%, and the carbon-containing materials are selected from one or more compounds of coke powder, coking dust ash, and anthracite; The mass of the hot metallized pellets collected by the steelmaking covered closed slag bag is defined as Q1, and the mass of the carbon-containing materials added subsequently is defined as Q2, then Q2 = (Q1 / w) * C; wherein w represents the carbon content of the carbon-containing material, and C represents a constant with a value of 5% to 8%; Optionally, the carbon-containing material can also be selected from other types of carbon-containing substances alone or compounded to a carbon content of not less than 80%. In order to facilitate the reaction, the particle size of the added carbon-containing material cannot be too large. In the embodiment, the particle size of the carbon-containing material is selected as D, and D≤0.3mm.

[0044] In step 3), the preset time for the sealed insulation treatment of the steelmaking covered slag ladle is 5 to 10 minutes. The purpose of the sealed insulation treatment is to provide reaction time for the iron reduction in the metallized pellets. Optionally, in this solution, considering the on-site production rhythm, the preset time for the sealed insulation treatment of the steelmaking covered slag ladle is controlled to be 6 to 8 minutes. Hot steel slag will transform into a semi-solid state at 1200 to 1300°C and basically transform into a solid state at 1100 to 1200°C. During the transportation process, the surface of the liquid steel slag in the slag ladle will cool and form a solid state. The liquid steel slag inside will form an insulation layer with the solid state on the surface. During the 5 to 10 minutes of sealed insulation treatment time, the liquid steel slag inside will not solidify, ensuring the reaction effect. Therefore, in addition to controlling the sealed insulation treatment time to ensure the morphology of the hot steel slag, it is also necessary to control the temperature of the metallized pellets in the sealed slag ladle with a steelmaking cover.

[0045] Through the steps of the method for hot charging and hot use of metallized pellets in a rotary hearth furnace, the method can achieve an iron recovery rate of 55-75% in the metallized pellets, which not only utilizes the waste heat of the metallized pellets but also significantly improves the iron recovery rate.

[0046] The system of the method for hot charging and hot use of metallized pellets in a rotary hearth furnace is specifically composed of the following: a rotary hearth furnace 1, a spiral discharger 2, a guide chute 3, a cooling drum 4, a dust removal protection cover 5, a steelmaking covered closed slag bag 6, a guide pipe 7 and a slag pool; a schematic diagram of hot charging of hot metallized pellets into the steelmaking covered closed slag bag is shown in FIG. Figure 2 As shown, a screw discharger 2 is located at the bottom of the rotary hearth furnace 1 and is used to discharge the materials from the rotary hearth furnace 1. A guide chute 3 has one end located at the discharge end of the screw discharger 2 and the other end connected in sequence to a guide pipe 7 and a cooling drum 4, used to transport the discharge from the rotary hearth furnace 1 in two ways. The steelmaking covered and sealed slag ladle 6 is located at the discharge end of the guide pipe 7 and receives the metallized pellets transported from the discharge end of the guide pipe 7. The dust removal protective cover 5 is mounted between the discharge end of the guide pipe 7 and the outside of the steelmaking covered and sealed slag ladle 6. The cooling drum 4 cools some of the discharged metallized pellets before transporting them to other processing workshops.

[0047] During operation, the steelmaking covered closed slag ladle 6 is first placed at the discharge end of the guide pipe 7 to receive the hot metallized pellets discharged from the rotary hearth furnace 1, and is sealed and insulated; then it is transported to the steelmaking slag outlet, and carbon-containing materials are added to the steelmaking covered closed slag ladle 6 containing the hot metallized pellets before slag discharge, and then the slag is discharged to receive the hot steel slag and is sealed and insulated; finally, the completely sealed and insulated steelmaking covered closed slag ladle 6 is transported to the front of the slag stewing pool, poured into the slag stewing pool for slag stewing treatment, and the slag is recovered by rod mill magnetic separation and magnetic separation.

[0048] The method and system for hot charging and using metallized pellets in a rotary hearth furnace disclosed in the present invention will be further specifically introduced below with reference to the accompanying drawings.

[0049] Example 1

[0050] (1) Place the steelmaking covered sealed slag ladle 6 below the guide chute 3 below the rotary hearth furnace 1, load 5 tons of hot metallized pellets into it, and seal it to keep it warm.

[0051] (2) The steelmaking covered sealed slag ladle 6 containing hot metallized pellets is transported to the steelmaking slag outlet. Before slag discharge, 220 kg of coke powder is added to the slag ladle. Then, 50 tons of hot steel slag is added to the slag ladle. Then, the steelmaking covered sealed slag ladle 6 is sealed and insulated.

[0052] (3) Sealing and heat preservation for 6 minutes, then transporting the steelmaking covered sealed slag bag 6 to the front of the slag stewing pool and pouring it into the slag stewing pool for slag stewing treatment;

[0053] (4) After the slag treatment is completed, the slag steel and magnetic separation powder are recovered by rod mill magnetic separation.

[0054] Before treatment, the total iron content of the metallized pellets was about 60%, and the metallic iron content was about 40%; after treatment, 380 kg of slag steel and 200 kg of magnetic separation powder were recovered per ton of metallized pellets, of which the slag steel grade was 80%, the magnetic separation powder iron grade was 50%, and the iron recovery rate of the metallized pellets was 67.33%.

[0055] Example 2

[0056] (1) Place the steelmaking covered sealed slag ladle 6 below the guide chute 3 below the rotary hearth furnace 1, load 10 tons of hot metallized pellets into it, and seal it to keep it warm.

[0057] (2) The steelmaking covered sealed slag ladle 6 containing the hot metallized pellets is transported to the steelmaking slag outlet. Before slag discharge, 440 kg of coke powder is added to the slag ladle. Then, 50 tons of hot steel slag is added to the slag ladle. Then, the steelmaking covered sealed slag ladle 6 is sealed and insulated.

[0058] (3) Sealing and heat preservation for 6 minutes, then transporting the steelmaking covered sealed slag bag 6 to the front of the slag stewing pool and pouring it into the slag stewing pool for slag stewing treatment;

[0059] (4) After the slag treatment is completed, the slag steel and magnetic separation powder are recovered by rod mill magnetic separation.

[0060] Before treatment, the total iron content of the metallized pellets was about 60%, and the metallic iron content was about 40%. After treatment, 350 kg of slag steel and 180 kg of magnetic separation powder were recovered per ton of metallized pellets, of which the slag steel grade was 80%, the magnetic separation powder iron grade was 50%, and the iron recovery rate of the metallized pellets was 61.66%.

[0061] Example 3

[0062] (1) Place the steelmaking covered sealed slag ladle 6 below the guide chute 3 below the rotary hearth furnace 1, load 5 tons of hot metallized pellets into it, and seal it to keep it warm.

[0063] (2) The steelmaking covered sealed slag ladle 6 containing the hot metallized pellets is transported to the steelmaking slag outlet. Before slag discharge, 300 kg of coke powder is added to the slag ladle. Then, 50 tons of hot steel slag is added to the slag ladle. Then, the steelmaking covered sealed slag ladle 6 is sealed and insulated.

[0064] (3) Sealing and heat preservation for 6 minutes, then transporting the steelmaking covered sealed slag bag 6 to the front of the slag stewing pool and pouring it into the slag stewing pool for slag stewing treatment;

[0065] (4) After the slag treatment is completed, the slag steel and magnetic separation powder are recovered by rod mill magnetic separation.

[0066] Before treatment, the total iron content of the metallized pellets was about 60%, and the metallic iron content was about 40%; after treatment, 390 kg of slag steel and 220 kg of magnetic separation powder were recovered per ton of metallized pellets, of which the slag steel grade was 80%, the magnetic separation powder iron grade was 50%, and the iron recovery rate of the metallized pellets was 69%.

[0067] Example 4

[0068] (1) Place the steelmaking covered sealed slag bag under the rotary hearth furnace discharge chute, load 5t of hot metallized pellets, and seal it to keep it warm.

[0069] (2) The slag bag containing hot metallized pellets is transported to the steelmaking slag outlet. Before slag discharge, 300 kg of coke powder is added to the slag bag, followed by 50 tons of hot steel slag.

[0070] (3) Before the slag bag is transported to the slag stewing pool, it is poured into the slag stewing pool for slag stewing treatment. The process time is 8 minutes, followed by slag stewing-rod grinding-magnetic separation to recover slag steel and magnetic separation powder.

[0071] Before treatment, the total iron content of the metallized pellets was about 60%, and the metallic iron content was about 40%; after treatment, 395 kg of slag steel and 225 kg of magnetic separation powder were recovered per ton of metallized pellets, of which the slag steel grade was 80%, the magnetic separation powder iron grade was 50%, and the iron recovery rate of the metallized pellets was 71.41%.

[0072] Theoretically, the iron recovery rate of metallized pellets is determined by the following factors: 1) the amount of metallized pellets added. The greater the amount of pellets added, the lower the iron recovery rate; 2) the amount of carbon source added. Within a limited range, the more carbon source added, the higher the iron recovery rate; 3) the time of closed heat preservation treatment. Within a limited range, the longer the treatment time, the higher the iron recovery rate. The above embodiment comprehensively considers economic cost and on-site production rhythm, controls the amount of metallized pellets added to the reaction, the amount of carbon-containing materials added, and the closed treatment time to calculate the iron recovery rate of the metallized pellets. The results show that under the conditions of controlling the ratio of C in the carbon source to the unreduced Fe in the metallized pellets in the closed slag bag 6 with a cover of 0.5-0.7 and the closed reaction time of 6-8 minutes, the method of hot charging and hot use of metallized pellets in the rotary hearth furnace can control the recovery rate of iron in the metallized pellets within the range of 55-75%. This not only proposes a new application path for metallized pellets, but also makes full use of the waste heat of the pellets and the sensible heat of the slag to improve energy utilization.

[0073] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for hot charging and hot use of metallized pellets in a rotary hearth furnace, characterized in that: The steps include: 1) Use a steelmaking covered closed slag ladle to receive hot metallized pellets in a preset proportion and seal and keep warm; 2) adding carbon-containing materials and hot steel slag into a steelmaking covered sealed slag ladle containing hot metallized pellets in sequence, and then performing a sealing and heat preservation treatment on the steelmaking covered sealed slag ladle; 3) After the sealed heat preservation treatment reaches the preset time, all the materials in the sealed slag bag with a cover are poured into the slag stewing tank for slag stewing treatment; 4) After the slag treatment is completed, the slag steel and magnetic separation powder are recovered by rod mill magnetic separation.

2. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The specific process of using a steelmaking covered closed slag ladle to receive hot metallized pellets according to a preset ratio is as follows: Determine the maximum mass of hot slag that can be added based on the capacity of the steelmaking covered closed slag ladle; The maximum mass of the hot metallized pellets to be received from the steelmaking closed slag ladle with a lid is determined based on the maximum mass of the hot steel slag; wherein the mass ratio of the hot metallized pellets to the hot steel slag in the steelmaking closed slag ladle with a lid shall not exceed 0.

2.

3. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: When adding carbonaceous materials into the steelmaking closed slag ladle with a cover containing hot metallized pellets, the temperature of the hot metallized pellets in the steelmaking closed slag ladle with a cover is not lower than 700°C.

4. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The carbon content of the carbon-containing material is not less than 80%.

5. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The mass of the hot metallized pellets collected from the covered closed slag ladle for steelmaking is defined as Q1, and the mass of the carbon-containing material added subsequently is defined as Q2, then Q2 = (Q1 / w)*C; where w represents the carbon content of the carbon-containing material, and C represents a constant, which is 5% to 8%.

6. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The particle size of the carbon-containing material is D, D≤0.3mm.

7. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The preset time for the sealed heat preservation treatment of the steelmaking covered slag ladle is 5 to 10 minutes.

8. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The carbon-containing material is selected from one or more of coke powder, coking dust ash, and anthracite.

9. The method for hot charging and hot use of metallized pellets in a rotary hearth furnace according to claim 1, characterized in that: The method for hot charging and using the metallized pellets in the rotary hearth furnace can achieve a recovery rate of 55-75% for the iron element in the metallized pellets.

10. A system for hot charging and hot use of metallized pellets in a rotary hearth furnace according to any one of claims 1 to 9, characterized in that: It includes a rotary hearth furnace, a spiral discharger, a guide chute, a cooling cylinder, a dust removal protective cover, a steelmaking belt-covered sealed slag ladle, a guide pipe, and a slag pool; the spiral discharger is located at the bottom of the rotary hearth furnace and is used for discharging the rotary hearth furnace; one end of the guide chute is located at the discharge end of the spiral discharger, and the other end is connected to the guide pipe and the cooling cylinder in sequence, and is used to transport the discharge of the rotary hearth furnace in two ways; the steelmaking belt-covered sealed slag ladle is located at the discharge end of the guide pipe, and the dust removal protective cover is sleeved on the discharge end of the guide pipe and the outer side of the steelmaking belt-covered sealed slag ladle; The steelmaking covered closed slag ladle is first placed at the discharge end of the guide pipe to receive the hot metallized pellets discharged from the rotary hearth furnace, and is sealed and insulated; then it is transported to the steelmaking slag outlet, and carbon-containing materials are added to the steelmaking covered closed slag ladle containing the hot metallized pellets before slag discharge, and then the slag is discharged to receive the hot steel slag and is sealed and insulated for treatment; finally, the completely sealed and insulated steelmaking covered closed slag ladle is transported to the front of the slag stewing pool, poured into the slag stewing pool for slag stewing treatment, and the slag is recovered by rod mill magnetic separation and magnetic separation.

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