Method for combined treatment of metallurgical solid waste

Abstract

The invention discloses a method for combined treatment of metallurgical solid waste. The method is suitable for treating iron-containing and zinc-containing dust mud, tar residues, steel rolling oil sludge and other solid waste generated by iron and steel enterprises. The method comprises the following steps: dividing the solid waste into iron-containing and zinc-containing dust sludge and oil-containing sludge; pyrolyzing the steel rolling oil sludge and the tar residue in a rotary kiln (500-900 DEG C) to respectively obtain a high-iron material (Fegt; 65%) and a high carbon material (Cgt; 60%) and high calorific value flue gas; blast furnace ash, converter ash, electric furnace ash and a high-iron / high-carbon material are mixed according to the C / O ratio of 0.9-1.25, granulation is conducted, then direct reduction is conducted in a multi-hearth furnace (700-1100 DEG C), and direct reduction iron is obtained; smelting and reducing the directly reduced iron in an electric furnace (1400-1600 DEG C) to produce zinc oxide powder (zinc grade gt); 50%), molten iron and high-temperature slag. Through the synergistic effect of the rotary kiln, the multi-hearth furnace and the electric furnace, efficient recovery of iron, zinc, carbon and other valuable elements is achieved, flue gas is recycled, energy consumption is reduced, secondary pollution is reduced, economic and environmental benefits are achieved, and the method is suitable for solid waste recycling in the iron and steel industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical solid waste resource utilization, and relates to a method for jointly disposing of metallurgical solid waste, which is applicable to treating solid wastes such as iron and zinc-containing dust and sludge, tar slag, and rolling oil sludge generated by iron and steel enterprises, realizing the resource utilization of valuable elements and the energy cycle within the process system. Background Art

[0002] For every 1 t of crude steel produced by an iron and steel enterprise, about 0.35 kg of zinc-containing dust and sludge will be generated, and the vast majority of it is low-zinc dust and sludge, which is mainly treated by the rotary hearth furnace process. According to the iron and steel industry plan of our country, the proportion of short-process steelmaking in crude steel will gradually increase, and the generation amount of electric furnace dust is bound to increase, and its zinc content will reach about 20%; however, the rotary hearth furnace process is more suitable for treating zinc-containing dust and sludge with a zinc content of less than 5%. For every 1 t of coke produced by an iron and steel enterprise, about 0.5 kg of tar slag is generated, which is mainly treated by the process of blending coal for reuse. Using it as fuel will cause secondary pollution, and at the same time, the composition fluctuation will lead to unstable coke quality and increase the heat load of the coke oven. For every 1 t of rolled steel produced by an iron and steel enterprise, about 0.86 kg of rolling oil sludge will be generated. Improper disposal will inevitably affect air quality, damage soil structure, pollute groundwater sources, cause serious environmental pollution, and even threaten human health and safety.

[0003] Although the iron and zinc-containing dust and sludge, tar slag, and rolling oil sludge generated by iron and steel enterprises are solid wastes, they contain a large amount of valuable elements such as iron, zinc, and carbon. However, the methods for treating these solid wastes are single, and it is difficult to treat solid wastes with different material characteristics, and the valuable elements therein cannot be effectively utilized for resource. At present, the solid wastes generated by different production units in iron and steel enterprises have not yet formed a collaborative disposal process method; therefore, it is urgent to integrate solid waste disposal technical resources, break through the technical barriers between their material flow and energy flow, reduce the energy waste caused by independent disposal, realize the recycling of waste flue gas within the process system, and at the same time increase the product added value, providing an exploratory technical route for treating metallurgical solid waste. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to solve the above problems, and provide a method for jointly disposing of metallurgical solid waste, which combines the technical characteristics of a rotary kiln, a multi-hearth furnace, and an electric furnace to jointly dispose and centrally consume metallurgical solid wastes with different characteristics generated by iron and steel enterprises, and help realize the resource utilization of metallurgical solid waste.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A method for jointly disposing of metallurgical solid waste, comprising the following steps:

[0007] (1) According to the physical and chemical properties of metallurgical solid waste, it is divided into iron-containing zinc dust mud and oil-containing sludge. Iron-containing zinc dust mud includes blast furnace dust, converter dust and electric furnace dust, and oil-containing sludge includes tar residue and steel rolling oil sludge.

[0008] (2) The steel rolling sludge is sent to a rotary kiln for pyrolysis treatment at a pyrolysis temperature of 500°C to 900°C to obtain a high-iron material with an Fe content greater than 65% and a high calorific value pyrolysis flue gas;

[0009] (3) The tar residue is fed into a rotary kiln for pyrolysis treatment at a temperature of 500°C to 900°C to obtain a high-carbon material with a carbon content greater than 60% and a high-calorific value pyrolysis flue gas;

[0010] (4) Blast furnace ash, converter ash, electric furnace ash, binder, and the high iron material produced in step (2) and / or the high carbon material produced in step (3) are mixed at a C / O ratio of 0.9 to 1.25, humidified and evenly mixed, and then granulated to obtain wet balls, which are then dried and fed into a multi-chamber furnace, first dried and dehydrated in a calcining zone, and then fed into a reduction zone for direct reduction reaction to obtain direct reduced iron;

[0011] (5) The direct reduced iron obtained in step (4) is fed into an electric furnace for a smelting reduction reaction at a smelting reduction temperature of 1400° C. to 1600° C. to obtain zinc oxide powder, molten iron and high-temperature slag, wherein the zinc grade of the zinc oxide powder is greater than 50%.

[0012] Furthermore, in step (2) and step (3), the steel rolling sludge and tar residue are dried and dehydrated before being sent to the rotary kiln, the drying temperature is 100° C. to 200° C., and the moisture content after drying is not higher than 2%.

[0013] Furthermore, in step (2) and step (3), the high calorific value pyrolysis flue gas generated by the rotary kiln pyrolysis is treated and used as fuel for the multi-hearth furnace, and the high iron material and high carbon material produced are used as ingredients for step (4).

[0014] Furthermore, in step (4), the binder is selected from one or more combinations of organic binders, composite binders, and bentonite, and the content of the binder in the ingredients is 2% to 3%.

[0015] Furthermore, in step (4), the wet ball particle size of the granulated product is 8 mm to 15 mm, the moisture content is 9% to 14%, and the moisture content after drying is not higher than 2%.

[0016] Furthermore, in step (4), the temperature of the calcination zone of the multi-hearth furnace is 700°C to 900°C, the temperature of the reduction zone is 1000°C to 1100°C, and the reduction time is 40min to 60min.

[0017] Further, in step (4), the flue gas generated by the multi-hearth furnace is used for drying steel rolling sludge or tar residue after treatment, and the secondary zinc oxide powder generated by the multi-hearth furnace is used as a raw material for zinc smelting.

[0018] Further, in step (5), the electric furnace melting reduction time is 30 min to 60 min, and the generated flue gas is used for drying the wet balls of the multi-hearth furnace after treatment.

[0019] Further, in step (5), the molten iron water is used for refining or continuous casting, the high-temperature slag is slowly cooled to obtain materials with different crystal structures for external sales, and the zinc oxide powder is sold as a raw material for zinc smelting.

[0020] Further, in step (1), the iron and zinc-containing dust and sludge are classified into low-zinc dust and sludge with Zn < 4%, medium-zinc dust and sludge with 4% < Zn < 20%, and high-zinc dust and sludge with Zn > 20% according to the zinc content; among them, the chemical composition of blast furnace ash is Zn 1% - 7%, Fe 25% - 40%, C 15% - 30%, the chemical composition of converter ash is Zn 0.1% - 5%, Fe 20% - 45%, Ca 5% - 15%, C < 2%, and the chemical composition of electric furnace ash is Zn 8% - 30%, Fe 35% - 50%, C < 2%; the chemical composition of tar residue is C 55% - 92%, S 0.5% - 1.9%, the moisture content is 1.5% - 30%, and the calorific value range is 27 MJ·kg-1 - 39 MJ·kg-1; the chemical composition of steel rolling sludge is iron shaving particles 50% - 70%, mineral oil 10% - 30%, and the moisture content is 5% - 20%.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. Joint and collaborative disposal, significantly improving the resource utilization efficiency: Through the joint and collaborative action of the rotary kiln, multi-hearth furnace and electric furnace, the present invention classifies and disposes of the physical and chemical properties of iron and zinc-containing dust and sludge, tar residue and steel rolling sludge, realizing the centralized disposal of various solid wastes and the efficient recovery of valuable elements. The pyrolysis of the rotary kiln converts steel rolling sludge and tar residue into high-iron materials (Fe > 65%) and high-carbon materials (C > 60%) respectively. These materials are synergistically proportioned with blast furnace ash, converter ash and electric furnace ash in the multi-hearth furnace, optimizing the connection of the material flow. The combined process of direct reduction in the multi-hearth furnace and melting reduction in the electric furnace further separates zinc and iron, producing high-grade zinc oxide powder (zinc grade > 50%) and molten iron water, significantly improving the resource utilization efficiency of elements such as iron, zinc and carbon, and reducing the occupation of land by solid waste accumulation.

[0023] 2. Internal energy co - cycle in the process, with prominent energy - saving and emission - reduction effects: Through the combined process design, the present invention realizes the deep coordination of material flow and energy flow, significantly reducing energy consumption. The high - calorific - value flue gas generated by pyrolysis in the rotary kiln is directly used as fuel for the multi - hearth furnace after treatment, reducing external fuel consumption; the high - temperature flue gas from the electric furnace is used for wet - ball drying, and the flue gas from the multi - hearth furnace is used for drying oily sludge, forming a closed - loop utilization of the energy flow and efficiently recovering sensible heat. Compared with the traditional independent disposal process, the present invention reduces the direct emission of high - temperature flue gas, reduces the heat - energy loss of the process system, reduces the emission of secondary pollutants (such as sulfides and polycyclic aromatic hydrocarbons), enhances environmental compliance, and contributes to green and low - carbon development.

[0024] 3. Synergistic product value - addition, maximizing economic benefits: The combined and synergistic process of the present invention produces high - value - added products, significantly enhancing economic benefits. The molten iron produced by the electric furnace can be directly used for refining or continuous casting to meet the needs of steel production; the zinc oxide powder (zinc grade > 50%) co - produced by the multi - hearth furnace and the electric furnace is used as a high - value raw material for zinc smelting, with broad market prospects; the high - temperature slag forms materials with different crystal structures through slow cooling, which is suitable for the construction or functional material fields, expanding the application scenarios. This multi - product synergistic value - addition model converts solid waste into high - value commodities, reduces the disposal cost, and creates significant economic benefits.

[0025] 4. Synergistic design improves process adaptability, with wide application prospects: Through the combined and synergistic process design, the present invention can flexibly adapt to the characteristics of different zinc - content dusts (low - zinc, medium - zinc, high - zinc) and oily sludge, realizing the comprehensive disposal of various solid wastes. The synergistic effect of the rotary kiln, multi - hearth furnace, and electric furnace integrates mature technologies, and the equipment has strong versatility, facilitating popularization and application in existing steel enterprises. By precisely controlling parameters such as the C / O ratio, temperature, and reduction time, the stability of product quality is ensured. This combined and synergistic process framework provides a replicable technical route for the resource utilization of metallurgical solid waste, with broad promotion prospects.

[0026] 5. Environmentally sustainable, with significant social benefits: The combined and synergistic disposal strategy of the present invention significantly reduces the pollution risk of solid waste to soil, groundwater, and air through resource utilization and energy recycling, avoids long - term environmental hazards brought by traditional landfilling or incineration, and reduces environmental governance costs. The process reduces the emission of secondary pollutants through synergistic optimization, meeting the requirements of national circular economy and environmental protection policies. The combined process improves the resource utilization efficiency of the steel industry, improves the surrounding ecological environment, provides technical support for the sustainable development of the industry, and brings significant social benefits.

[0027] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0029] Figure 1 is the process flow diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following uses specific specific examples to illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0031] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged, or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0032] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] Embodiment 1

[0034] Please refer to Figure 1 , which is a method for jointly disposing metallurgical solid waste, including the following steps:

[0035] (1) According to the physical and chemical properties of metallurgical solid waste to be treated, it can be divided into iron- and zinc-containing dust and sludge and oily sludge. Among them, the iron- and zinc-containing dust and sludge can be divided into low-zinc dust and sludge (Zn < 4%), medium-zinc dust and sludge (4% < Zn < 20%), and high-zinc dust and sludge (Zn > 20%), mainly including blast furnace ash, converter ash, and electric furnace ash. The main chemical components of blast furnace ash are: Zn (1% - 7%), Fe (25% - 40%), C (15% - 30%); the main chemical components of converter ash are: Zn (0.1% - 5%), Fe (20% - 45%), Ca (5% - 15%), C (< 2%); the main chemical components of electric furnace ash are: Zn (8% - 30%), Fe (35% - 50%), C (< 2%). The oily sludge mainly includes tar slag and steel rolling oily sludge. Tar slag contains pulverized coal, coke powder, coal tar dendritic polymers, and mechanical impurities, and also contains benzene, phenol, and polycyclic aromatic hydrocarbons, etc. Steel rolling oily sludge is a by-product generated during the steel rolling process, mainly composed of iron filings, mineral oil, water, etc. The main chemical components of tar slag are: C (55% - 92%), S (0.5% - 1.9%), moisture content 1.5% - 30%, and its calorific value ranges from 27 MJ·kg-1 to 39 MJ·kg-1; the main chemical components of steel rolling oily sludge are: iron shaving particles (50% - 70%), mineral oil (10% - 30%), moisture content 5% - 20%, and in addition, it also contains a small amount of elements such as Cr and Ni.

[0036] (2) The steel rolling oily sludge is dispersed and then sent to a drying device for dehydration treatment. After the drying and dehydration treatment, the water content in the steel rolling oily sludge is not higher than 2%, and the drying temperature is controlled within the range of 100°C to 200°C; the dried steel rolling oily sludge is sent into a rotary kiln through a feeding device for pyrolysis treatment. The raw material enters the rotary kiln from the kiln tail, and after pyrolysis, it exits from the kiln head. The pyrolysis temperature is 500°C to 900°C, obtaining high-iron materials and high-calorific value flue gas; the Fe content in the high-iron materials is above 65%, which is used for the batching of a multiple hearth furnace, and the high-calorific value flue gas is used as the fuel for the multiple hearth furnace.

[0037] (3) The tar slag is dispersed and crushed into particles smaller than 5 mm and then sent to a drying device for dehydration treatment. After the drying and dehydration treatment, the water content in the tar slag is not higher than 2%, and the drying temperature is controlled within the range of 100°C to 200°C; the dried tar slag is sent into a rotary kiln through a feeding device for pyrolysis treatment. The pyrolysis temperature is 500°C to 900°C. The tar slag is sent into the rotary kiln from the kiln tail, and after pyrolysis, it exits from the kiln head, obtaining high-carbon materials and high-calorific value flue gas; the C content in the high-carbon materials is above 60%, which is used for the batching of a multiple hearth furnace, and the high-calorific value flue gas is used as the fuel for the multiple hearth furnace.

[0038] (4) Blast furnace ash, converter ash, electric furnace ash, binder, high carbon material and high iron material produced by the rotary kiln are mixed according to a C / O ratio of 0.9 to 1.25, and the mixed raw materials are sent to a mixing device for humidification and mixing. The mixed wet materials are granulated and formed to obtain wet balls, and the wet ball water content is about 12%. The wet balls are then sent to a drying device for drying until the water content is less than 2%. The dried balls are sent to a multi-hearth furnace through a feeding device, first dried and dehydrated in a calcining zone, and the temperature of the calcining zone is controlled within the range of 700°C to 900°C, and then enter the bottom reduction zone for direct reduction reaction, and the temperature of the reduction zone is controlled within the range of 1000°C to 1100°C to obtain direct reduced iron;

[0039] (5) The obtained direct reduced iron is discharged from the discharge port of the bottom layer and then fed into an electric furnace for a smelting reduction reaction. The smelting reduction temperature is about 1400°C. The obtained products are zinc oxide powder, molten iron and high-temperature slag. The zinc oxide powder can be sold as a zinc smelting raw material, the molten iron can be used for steelmaking or continuous casting, and the high-temperature slag can be slowly cooled to obtain materials with different crystal structures for sale. The zinc grade of the zinc oxide powder is above 50%.

[0040] Among them, the binder can be one or a combination of organic binders, composite binders, and bentonite. The diameter of the granulated pellets is in the range of 8mm to 15mm. The reaction time in the multi-chamber furnace is 40min, and the reaction time in the electric furnace is 30min. The high-temperature flue gas generated by the electric furnace is used for wet-bulb drying in the multi-chamber furnace after treatment. The high-calorific value flue gas generated by the rotary kiln is used as fuel for the multi-chamber furnace after treatment. The flue gas generated by the multi-chamber furnace can be used for drying oil-containing sludge after treatment.

[0041] Example 2

[0042] See also Figure 1 , which is a method for the combined disposal of metallurgical solid waste, comprising the following steps:

[0043] (1) According to the physical and chemical properties of metallurgical solid waste to be processed, it can be divided into iron- and zinc-containing dust and sludge and oil-containing sludge. Among them, the iron- and zinc-containing dust and sludge is divided into low-zinc dust and sludge (Zn < 4%), medium-zinc dust and sludge (4% < Zn < 20%), and high-zinc dust and sludge (Zn > 20%), mainly including blast furnace ash, converter ash, and electric furnace ash. The chemical composition of blast furnace ash is: Zn 2% - 6%, Fe 30% - 38%, C 20% - 28%. The chemical composition of converter ash is: Zn 0.2% - 4%, Fe 25% - 42%, Ca 6% - 12%, C < 1.5%. The chemical composition of electric furnace ash is: Zn 10% - 25%, Fe 38% - 48%, C < 1.5%. The oil-containing sludge includes tar slag and steel rolling oil sludge. Tar slag contains pulverized coal, coke powder, coal tar dendritic polymers, and mechanical impurities, containing benzene, phenol, and polycyclic aromatic hydrocarbons, etc. The chemical composition is: C 60% - 90%, S 0.6% - 1.8%, moisture content 2% - 25%, and the calorific value ranges from 28 MJ·kg-1 to 38 MJ·kg-1. The steel rolling oil sludge is composed of iron filings, mineral oil, water, etc. The chemical composition is: iron filing particles 55% - 68%, mineral oil 12% - 28%, moisture content 6% - 18%, containing a small amount of elements such as Cr and Ni.

[0044] (2) The steel rolling oil sludge is dispersed and then sent to a drying device for dehydration treatment. The drying temperature is controlled at 120°C - 180°C, and the moisture content after drying is not higher than 1.5%. The dried steel rolling oil sludge is sent to a rotary kiln through a feeding device for pyrolysis treatment. The raw material enters from the kiln tail and exits from the kiln head after pyrolysis. The pyrolysis temperature is 600°C - 850°C, obtaining high-iron materials and high-calorific value flue gas. The Fe content in the high-iron materials is above 68%, which is used for charging the multi-hearth furnace. The high-calorific value flue gas is treated and used as the fuel for the multi-hearth furnace.

[0045] (3) The tar slag is dispersed and crushed into particles smaller than 4 mm and then sent to a drying device for dehydration treatment. The drying temperature is controlled at 120°C - 180°C, and the moisture content after drying is not higher than 1.5%. The dried tar slag is sent to a rotary kiln through a feeding device for pyrolysis treatment. The pyrolysis temperature is 600°C - 850°C. The tar slag is fed from the kiln tail and exits from the kiln head after pyrolysis, obtaining high-carbon materials and high-calorific value flue gas. The C content in the high-carbon materials is above 65%, which is used for charging the multi-hearth furnace. The high-calorific value flue gas is treated and used as the fuel for the multi-hearth furnace.

[0046] (4) Charge blast furnace dust, converter dust, electric furnace dust, binder, high-carbon materials and high-iron materials produced by the rotary kiln according to a C / O ratio of 1.0 - 1.2. The prepared raw materials are sent to a mixing equipment for humidifying and mixing. The mixed wet materials are granulated and formed to obtain wet balls. The moisture content of the wet balls is about 11%, and the particle size is 10 mm - 14 mm. Subsequently, the wet balls are sent to a drying equipment to be dried until the moisture content is less than 1.5%. The dried balls are sent into a multi-hearth furnace through a feeding device. First, they are dried in the calcination zone to remove the bound water, and the temperature in the calcination zone is controlled at 750°C - 850°C. Then, they enter the bottom reduction zone for direct reduction reaction. The temperature in the reduction zone is controlled at 1020°C - 1080°C, and the reduction time is 45 minutes to obtain direct reduced iron.

[0047] (5) The obtained direct reduced iron is discharged from the bottom discharge port and sent to an electric furnace for smelting reduction reaction. The smelting reduction temperature is 1450°C - 1550°C, and the reaction time is 35 minutes. The obtained products are zinc oxide powder, molten iron and high-temperature slag. The zinc grade of the zinc oxide powder is above 55%, which can be sold as raw materials for zinc smelting. The molten iron is used for steelmaking or continuous casting. The high-temperature slag is slowly cooled to obtain materials with different crystal structures for external sales.

[0048] Among them, the binder is a combination of bentonite and organic binder, with a content of 2.5%. The flue gas generated by the multi-hearth furnace is treated and used for drying oily sludge. The high-temperature flue gas generated by the electric furnace is treated and used for drying the wet balls of the multi-hearth furnace. The high-calorific value flue gas generated by the rotary kiln is treated and used as fuel for the multi-hearth furnace.

[0049] The present invention recycles the flue gas generated in each process, and the internal cross-union and deep treatment of the combined process complement each other, which is conducive to energy conservation and emission reduction, and at the same time realizes greater economic benefits.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for jointly disposing of metallurgical solid wastes, characterized in that It includes the following steps: (1) According to the physical and chemical properties of metallurgical solid waste, it is divided into iron- and zinc-containing dust and oil-containing slag mud. The iron- and zinc-containing dust includes blast furnace ash, converter ash, and electric furnace ash, and the oil-containing slag mud includes tar slag and steel rolling oil sludge; (2) Feed the steel rolling oil sludge into a rotary kiln for pyrolysis treatment at a pyrolysis temperature of 500°C to 900°C to obtain a high-iron material with an Fe content greater than 65% and high-calorie pyrolysis flue gas; (3) Feed the tar slag into a rotary kiln for pyrolysis treatment at a pyrolysis temperature of 500°C to 900°C to obtain a high-carbon material with a C content greater than 60% and high-calorie pyrolysis flue gas; (4) Charge the blast furnace ash, converter ash, electric furnace ash, binder, and the high-iron material produced in step (2) and / or the high-carbon material produced in step (3) according to a C / O ratio of 0.9 to 1.25, humidify and mix evenly, then granulate and form to obtain wet balls. After drying, the wet balls are fed into a multi-hearth furnace, first dried and dehydrated in the calcination zone, and then enter the reduction zone for direct reduction reaction to obtain direct reduced iron; (5) Feed the direct reduced iron obtained in step (4) into an electric furnace for smelting reduction reaction at a smelting reduction temperature of 1400°C to 1600°C to obtain zinc oxide powder, molten iron water, and high-temperature slag, where the zinc grade of the zinc oxide powder is greater than 50%.

2. The method for jointly disposing metallurgical solid waste according to claim 1, characterized in that: In steps (2) and (3), before feeding the steel rolling oil sludge and tar slag into the rotary kiln, they are first subjected to drying and dehydration treatment at a drying temperature of 100°C to 200°C, and the moisture content after drying is not higher than 2%.

3. The method for jointly disposing metallurgical solid waste according to claim 1, characterized in that: In steps (2) and (3), the high-calorie pyrolysis flue gas generated by the rotary kiln pyrolysis is treated and used as the fuel of the multi-hearth furnace, and the produced high-iron material and high-carbon material are used for the batching in step (4).

4. The method for jointly disposing metallurgical solid waste according to claim 1, wherein: In step (4), the binder is selected from one or a combination of organic binders, composite binders, and bentonite, and the content of the binder in the batching is 2% to 3%.

5. The method for jointly disposing metallurgical solid wastes according to claim 1, wherein: In step (4), the wet balls formed by granulation have a particle size of 8 mm to 15 mm, a moisture content of 9% to 14%, and the moisture content after drying is not higher than 2%.

6. The method for jointly disposing metallurgical solid waste according to claim 1, characterized in that: In step (4), the temperature of the calcination zone of the multi-hearth furnace is 700°C to 900°C, the temperature of the reduction zone is 1000°C to 1100°C, and the reduction time is 40 min to 60 min.

7. The method for jointly disposing metallurgical solid waste according to claim 1, characterized in that: In step (4), the flue gas generated by the multi-hearth furnace is treated and used for drying the steel rolling oil sludge or tar slag, and the produced secondary zinc oxide powder is used as a zinc smelting raw material.

8. The method for jointly disposing metallurgical solid waste according to claim 1, characterized in that: In step (5), the electric furnace smelting reduction time is 30 min to 60 min, and the generated flue gas is treated and used for drying the wet balls of the multi-hearth furnace.

9. The method for jointly disposing metallurgical solid waste according to claim 1, wherein: In step (5), the molten iron water is used for refining or continuous casting, the high-temperature slag is slowly cooled to obtain materials with different crystal structures for external sale, and the zinc oxide powder is sold as a zinc smelting raw material.

10. The method for jointly disposing metallurgical solid waste according to claim 1, wherein: In step (1), the iron- and zinc-containing dust and sludge are classified into low-zinc dust and sludge with Zn < 4%, medium-zinc dust and sludge with 4% < Zn < 20%, and high-zinc dust and sludge with Zn > 20%. Among them, the chemical composition of blast furnace ash is Zn 1% - 7%, Fe 25% - 40%, C 15% - 30%; the chemical composition of converter ash is Zn 0.1% - 5%, Fe 20% - 45%, Ca 5% - 15%, C < 2%; the chemical composition of electric furnace ash is Zn 8% - 30%, Fe 35% - 50%, C < 2%; the chemical composition of tar residue is C 55% - 92%, S 0.5% - 1.9%, moisture content 1.5% - 30%, and the calorific value ranges from 27 MJ·kg-1 to 39 MJ·kg-1; the chemical composition of steel rolling oil sludge is iron shaving particles 50% - 70%, mineral oil 10% - 30%, moisture content 5% - 20%.

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