Method for producing iron powder by solid reduction treatment of copper smelting slag in rotary kiln

Abstract

The invention discloses a method for producing iron powder by solid reduction treatment of copper smelting slag in a rotary kiln. Copper slag powder is obtained by crushing the copper smelting slag; carrying out solid-state reduction on the pellets containing the copper slag powder in a rotary kiln; carrying out magnetic separation on the reduced material to obtain iron powder and tailings; the pellets are fed into the rotary kiln from the tail of the rotary kiln, air is blown into the rotary kiln from a kiln head, and the reduced materials are discharged from the kiln head; the raw materials of the pellets comprise copper slag powder, limestone powder and pulverized coal. According to the method, the copper smelting slag is subjected to solid-state reduction treatment through the rotary kiln to comprehensively recover and produce the iron powder, and treatment and resource recycling of the copper smelting slag are achieved; the reduction, harmlessness and recycling of the industrial waste residues are realized, the investment is saved, the energy is saved, the consumption is reduced, the operation cost is low, and the popularization is easy.

Description

Technical Field

[0001] The present invention relates to a method for recycling and utilizing copper smelting slag as a resource, and in particular to a method for producing iron powder by reducing and treating copper smelting slag in a rotary kiln. Background Art

[0002] my country currently produces approximately 10 million tons of copper from minerals. Each ton of copper produced generates approximately 2 to 3 tons of copper smelting slag, resulting in an annual output of over 20 million tons of copper smelting slag. This copper smelting slag has a low copper grade and a high iron content (40% to 50%). However, this iron primarily exists in the form of fayalite, with a small amount of iron remaining as free hematite and magnetite. This results in poor magnetic separation of copper smelting slag, resulting in a direct mineral processing recovery rate of only 30 to 40%, and the mineral processing grade does not meet the minimum requirements for iron concentrate. This makes it difficult to concentrate the slag using conventional magnetic separation methods.

[0003] At present, except for a small amount of copper smelting slag used in the production of building materials, a large amount of copper slag can only be stored as industrial waste, resulting in a serious waste of resources. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln with a high iron recovery rate.

[0005] The present invention solves the technical problem by adopting the following technical solution: a method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln, wherein copper slag powder is obtained by crushing the copper smelting slag; pellets containing the copper slag powder are solid-state reduced at 1100°C to 1200°C in a rotary kiln; the resulting reduced material is subjected to magnetic separation to obtain iron powder and tailings;

[0006] The pellets are fed into the rotary kiln from the rear of the rotary kiln, air is blown into the kiln head, and the reduced materials are discharged from the kiln head;

[0007] The raw materials of the pellets include copper slag powder, limestone powder and pulverized coal; the weight ratio of the copper slag powder, limestone powder and pulverized coal is 100:3-15:20-40.

[0008] Preferably, the diameter of the pellets is 25 to 35 mm.

[0009] Preferably, the copper content in the copper smelting slag is less than 0.5 wt%.

[0010] Preferably, the iron content in the copper smelting slag is 30 wt% to 60 wt%.

[0011] Preferably, the particle size of the copper slag powder is less than 40 mesh.

[0012] Preferably, the particle size of the pulverized coal is 0.1 to 0.5 mm.

[0013] Preferably, the moisture content of the pulverized coal is below 8 wt%.

[0014] Preferably, the weight ratio of the copper slag powder, limestone powder and pulverized coal is 100:5-12:25-35.

[0015] Preferably, the pellets are strong enough to be dropped from a height of 2 m for more than 2 times without breaking.

[0016] Preferably, the pellets are prepared by uniformly mixing the raw materials and the binder, controlling the moisture content to be 4wt% to 6wt%, and performing extrusion molding.

[0017] Preferably, the reduced material is crushed to a particle size of less than or equal to 80 mesh before the magnetic separation.

[0018] Preferably, the tailings are slurried and then flotation is performed to produce carbon powder and tailings.

[0019] Preferably, the flue gas in the solid-state reduction process is collected and the dust is collected to obtain the metal oxide product.

[0020] The present invention has the following beneficial effects:

[0021] (1) The present invention uses a rotary kiln solid-state reduction technology to treat copper smelting slag to comprehensively recover and produce iron powder, thereby achieving the treatment, disposal and resource recovery of copper smelting waste slag;

[0022] (2) The present invention realizes the reduction, harmlessness and resource utilization of industrial waste residues, saves investment, saves energy and reduces consumption, has low operating costs and is easy to promote.

[0023] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 This is a process flow chart for producing iron powder by solid-state reduction treatment of copper smelting slag in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, scheme and beneficial technology of the present invention clearer, the present invention is further described in detail below with reference to the embodiments and drawings. It should be noted that the embodiments described in this specification are only for explaining the present invention and are not intended to limit the present invention.

[0027] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0028] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and the "multiple" in "one or more" means two or more, and the "multiple" in "one or more" means two or more.

[0029] An embodiment of the present invention provides a method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln, wherein copper slag powder is obtained by crushing the copper smelting slag; pellets containing the copper slag powder are solid-state reduced at 1100°C to 1200°C in a rotary kiln; and the resulting reduced material is subjected to magnetic separation to obtain iron powder and tailings.

[0030] The pellets are fed into the rotary kiln from the rear of the rotary kiln, air is blown into the kiln head, and the reduced materials are discharged from the kiln head;

[0031] The raw materials of the pellets include copper slag powder, limestone powder and pulverized coal; the weight ratio of the copper slag powder, limestone powder and pulverized coal is 100:3-15:20-40.

[0032] Pulverized coal acts as a fuel and reducing agent and can be obtained by grinding carbon materials such as carbon concentrate, coke, granular coal, spent activated carbon, and semi-coke. Limestone acts as a flux.

[0033] In order to ensure that the solid-state reduction process in the rotary kiln can proceed smoothly and the reduction reaction is more thorough, the copper smelting slag, reducing agent, and flux need to be ground and mixed evenly, and then made into pellets. After solid-state reduction, iron and other metals are basically converted into metallic iron, making the iron optional. The main reduction reactions involved in this process are:

[0034] 2FeO·SiO2+2C=2Fe+SiO2+2CO (1)

[0035] Fe3O4+4C=3Fe+4CO (2)

[0036] FeO+CO=Fe+CO2 (3)

[0037] The method for producing iron powder by solid-state reduction treatment of copper smelting slag provided in an embodiment of the present invention has the following advantages:

[0038] (1) The embodiment of the present invention uses a rotary kiln solid-state reduction technology to treat copper smelting slag to comprehensively recover and produce iron powder, thereby achieving the treatment, disposal and resource recycling of copper smelting waste slag;

[0039] (2) The embodiments of the present invention achieve the reduction, harmlessness and resource utilization of industrial waste residues, save investment, save energy and reduce consumption, have low operating costs and are easy to promote.

[0040] In an embodiment of the present invention, the diameter of the pellets is 25 to 35 mm. The pellets may be spherical or / and ellipsoidal.

[0041] In an embodiment of the present invention, the copper content in the copper smelting slag is less than 0.5 wt%.

[0042] In an embodiment of the present invention, the iron content in the copper smelting slag is 30 wt% to 60 wt%.

[0043] In an embodiment of the present invention, the particle size of the copper slag powder is less than 40 mesh.

[0044] In an embodiment of the present invention, the particle size of the pulverized coal is 0.1-0.5 mm.

[0045] In an embodiment of the present invention, the moisture content of the pulverized coal is below 8 wt %.

[0046] In an embodiment of the present invention, the weight ratio of the copper slag powder, limestone powder and pulverized coal is 100:5-12:25-35.

[0047] In embodiments of the present invention, the pellets are strong enough to withstand being dropped from a height of 2 meters at least twice without breaking. Achieving this strength prevents the pellets from breaking or pulverizing during the reduction process, ensuring a stable reducing environment created by the oxidation of pulverized coal within the pellets, enabling smooth rotary kiln reduction and facilitating collection of reduced material after the reduction is complete.

[0048] In an embodiment of the present invention, the pellets are produced by uniformly mixing raw materials and a binder, controlling the moisture content to 4wt% to 6wt%, and then extruding the mixture. The binder can be in liquid, solid, or other form, as long as it can be uniformly mixed to provide a binding effect and suitable strength.

[0049] In an embodiment of the present invention, the reduced material is crushed to a particle size of less than or equal to 80 mesh before the magnetic separation.

[0050] The magnetic separation in the embodiment of the present invention can be carried out in a conventional manner. The magnetic components in the obtained reduced material are mostly iron and its oxides, so the selectivity is very good. The iron content of the obtained iron powder can reach more than 90%, and the iron recovery rate can reach more than 85%.

[0051] In an embodiment of the present invention, the tailings are slurried and then subjected to flotation to produce carbon powder and tailings. The obtained carbon powder can be returned to the ingredients for use, and the carbon recovery rate after flotation can reach 65%; the obtained tailings can be used as building material additives.

[0052] In an embodiment of the present invention, solid-state reduction is performed in a rotary kiln. Pellets containing the copper slag powder are fed into the rotary kiln from the rear end, air is introduced through the kiln head, and the reduced material is discharged from the kiln head. This solution requires a relatively low temperature for solid-state reduction of the pellets, and the material remains in a solid state during solid-state reduction, thus achieving the reduction reaction. This reduces the refractory requirements of the reaction equipment and makes the process easier to implement, thus enabling the process to be performed in a rotary kiln.

[0053] In an embodiment of the present invention, the flue gas from the solid-state reduction process is collected and dust is collected to obtain metal oxide products such as lead and zinc. Volatile metals such as lead and zinc volatilize into the flue gas during the solid-state reduction process and are ultimately collected and recovered in the dust collection system as oxide dust.

[0054] Example

[0055] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight. Unless otherwise stated, all reagents used in the examples are available through conventional commercial sources or synthesized according to conventional methods and can be used directly without further processing. Unless otherwise stated, all instruments used in the examples are available through conventional commercial sources.

[0056] Example 1

[0057] This embodiment is based on a rotary kiln built in a smelting enterprise in Yunnan Province. A production line for producing iron powder is produced by reducing copper smelting slag using a rotary kiln. The main components of the copper smelting slag involved in this embodiment are:

[0058] Element Cu Zn S Fe Pb Ca <![CDATA[SiO2]]> content / % 0.14 1.15 0.25 46.65 0.22 6.50 9.03

[0059] The composition of the raw coal involved is:

[0060] Element C H S N O <![CDATA[H2O]]> Ash content / % 74.4 4.21 0.5 0.42 3.37 0.8 16.23

[0061] The specifications of the rotary kiln used are The process flow of this embodiment is shown in Figure 1 , the specific method is as follows:

[0062] 1) Pulverized coal preparation

[0063] Raw coal is crushed and ball-milled to 0.25mm to produce pulverized coal. If the raw coal contains more than 8wt% moisture, dry hot air is introduced during pulverization to reduce the moisture content of the resulting pulverized coal to below 8wt%. In this embodiment, the dry hot air is supplied by a natural gas hot air furnace. The pulverized coal produced by the pulverizer is conveyed by air to a dust collector located at the top of the pulverized coal silo. The pulverized coal is then separated by dust bags and enters the silo, where the gas is discharged into the atmosphere.

[0064] 2) Granulation of ingredients

[0065] Copper smelting slag is crushed and ball-milled to produce copper slag powder with a particle size of less than 40 mesh. The copper slag powder, limestone powder, and pulverized coal are metered by weighing feeders at the bottom of the silo and fed onto a mixing conveyor. The weight ratio of copper slag powder, limestone powder, and pulverized coal is 100:8:30. The materials on the mixing conveyor enter a twin-shaft mixer for uniform mixing. During the mixing process, liquid and / or solid adhesives are added, and water is added to achieve a moisture content of 5wt%.

[0066] The evenly mixed material is added to the roller granulator and pressed into spherical or / and ellipsoidal pellets with a diameter of 25-35 mm. The pellets should be strong enough to withstand being dropped from a height of 2 m at least twice without breaking. Any material that leaks from the pelletizing process is returned to the twin-shaft mixer via a return conveyor. The pellets are then fed to the rotary kiln via a conveyor belt.

[0067] 3) Solid-state reduction

[0068] Pellets are fed into the rotary kiln from the rear via a conveyor belt. Air is forced into the kiln head, providing oxygen for combustion, ensuring full combustion of the pulverized coal in the pellets and creating a strong reducing atmosphere. The reduction temperature is 1100-1200°C, and the pellets remain solid. Zinc, lead, and cadmium are reduced to metals, which evaporate into metal vapor at high temperatures and enter the flue gas. Oxidation in the flue gas produces metal oxides, which accumulate in the dust collector, resulting in secondary zinc oxide. The flue gas, after dust collection, enters the scrubber for desulfurization and meets emission standards. The iron oxide component in the pellets is reduced to elemental iron, which enters the cooling drum along with the reduced material.

[0069] 4) Cooling ball mill

[0070] The reduced material obtained after the rotary kiln reduction is discharged from the rotary kiln head and enters the cooling cylinder for cooling. After cooling, it is sent to the dry ball mill for ball milling until the particle size is less than 80 mesh to obtain the reduced powder.

[0071] 5) Magnetic separation

[0072] The reduced powder is subjected to three-stage magnetic separation using a roller dry magnetic separator under weak magnetic field conditions (current 0.4A, magnetic field 1500Oe, magnetic plate spacing 4mm) to produce iron powder products and tailings.

[0073] 6) Tailings flotation

[0074] The tailings are slurried, subjected to one roughing and one sweeping process, to produce carbon powder and tailings. The carbon powder can be returned as pulverized coal ingredients, and the tailings can be sold as building materials.

[0075] The output products of this embodiment are as follows:

[0076] Iron powder: main grade iron content: 91.56%, iron recovery rate: 89.55%;

[0077] Carbon powder: main grade carbon content: 70.61%, carbon recovery rate: 65.6%;

[0078] Sub-zinc oxide powder in smoke: contains 24.43% zinc, 4.23% lead, and the recovery rate of zinc and lead is >95%.

[0079] The unit consumption indicators of this embodiment are: coal consumption 199.54kg / t slag, limestone powder consumption 49.87kg / t slag, binder consumption 30.56kg / t slag, electricity consumption 173.98kwh / t slag, and water consumption 1.06t / t slag.

[0080] The process method of this embodiment can be produced continuously, has a large processing capacity, relatively low consumption, a high recovery rate, and has a very good resource recovery effect.

[0081] Example 2

[0082] This embodiment uses a rotary kiln to reduce copper smelting slag to produce iron powder, wherein the main components of the copper smelting slag involved are:

[0083] Element Cu Zn S Fe Pb Ca <![CDATA[SiO2]]> content / % 0.37 2.91 1.52 54.76 1.20 1.55 24.97

[0084] The composition of the raw coal involved is:

[0085] Element C H S N O <![CDATA[H2O]]> Ash content / % 72.5 4.25 0.46 0.48 3.63 4.32 14.5

[0086] The specifications of the rotary kiln used are The specific process of this embodiment is as follows:

[0087] 1) Pulverized coal preparation

[0088] Raw coal is crushed and ball-milled to 0.5mm to produce pulverized coal. If the raw coal contains more than 8% moisture, dry hot air is introduced during pulverization to reduce the moisture content of the resulting pulverized coal to below 8wt%. In this embodiment, the dry hot air is supplied by a natural gas hot air furnace. The pulverized coal produced by the pulverizer is conveyed by air to a dust collector located at the top of the pulverized coal silo. The pulverized coal is then separated by dust bags and enters the silo, where the gas is discharged into the atmosphere.

[0089] 2) Granulation of ingredients

[0090] Copper smelting slag is crushed and ball-milled to produce copper slag powder with a particle size of less than 40 mesh. The copper slag powder, limestone powder, and pulverized coal are metered by weighing feeders at the bottom of the silo before entering a mixing conveyor. The weight ratio of copper slag powder, limestone powder, and pulverized coal is 100:10:35. The materials on the mixing conveyor enter a twin-shaft mixer for uniform mixing. During the mixing process, liquid and / or solid adhesives are added, and water is added to achieve a moisture content of 6wt%.

[0091] The evenly mixed material is added to the roller granulator and pressed into spherical or / and ellipsoidal pellets with a diameter of 25-35 mm. The pellets should be strong enough to withstand being dropped from a height of 2 m at least twice without breaking. Any material that leaks from the pelletizing process is returned to the twin-shaft mixer via a return conveyor. The pellets are then fed to the rotary kiln via a conveyor belt.

[0092] 3) Solid-state reduction

[0093] Pellets are fed into the rotary kiln from the rear via a conveyor belt. Air is forced into the kiln head, providing oxygen for combustion, ensuring full combustion of the pulverized coal in the pellets and creating a strong reducing atmosphere. The reduction temperature is 1100-1200°C, and the pellets remain solid. Zinc, lead, and cadmium are reduced to metals, which evaporate into metal vapor at high temperatures and enter the flue gas. Oxidation in the flue gas produces metal oxides, which accumulate in the dust collector, resulting in secondary zinc oxide. The flue gas, after dust collection, enters the scrubber for desulfurization and meets emission standards. The iron oxide component in the pellets is reduced to elemental iron, which enters the cooling drum along with the reduced material.

[0094] 4) Cooling ball mill

[0095] The reduced material obtained after the rotary kiln reduction is discharged from the rotary kiln head and enters the cooling cylinder for cooling. After cooling, it is sent to the dry ball mill for ball milling until the particle size is less than 80 mesh to obtain the reduced powder.

[0096] 5) Magnetic separation

[0097] The reduced powder is subjected to three-stage magnetic separation using a roller dry magnetic separator under weak magnetic field conditions (current 0.4A, magnetic field 1500Oe, magnetic plate spacing 4mm) to produce iron powder products and tailings.

[0098] 6) Tailings flotation

[0099] The tailings are slurried, subjected to one roughing and one sweeping process, to produce carbon powder and tailings. The carbon powder can be returned as pulverized coal ingredients, and the tailings can be sold as building materials.

[0100] The output products of this embodiment are as follows:

[0101] Iron powder: main grade iron content: 91.23%, iron recovery rate: 89.71%;

[0102] Carbon powder: main grade carbon content: 71.31%, carbon recovery rate: 66.32%;

[0103] Secondary zinc oxide powder in smoke: contains 32.43% zinc, 12.86% lead, and the recovery rate of zinc and lead is >95%.

[0104] The unit consumption indicators of this embodiment are: coal consumption 202.36kg / t slag, limestone powder consumption 50.75kg / t slag, binder consumption 29.60kg / t slag, power consumption 175.43kwh / t slag, and water consumption 0.92t / t slag.

[0105] The process of this embodiment has large processing capacity, low consumption, high recovery rate, and is suitable for large-scale industrial production.

[0106] Example 3

[0107] This embodiment uses a rotary kiln solid-state reduction method to treat copper smelting slag to produce iron powder. The main components of the copper smelting slag are:

[0108] Element Cu Zn S Fe Pb Ca <![CDATA[SiO2]]> content / % 0.27 2.27 0.12 40.44 0.54 1.42 28.41

[0109] The composition of the raw coal involved is:

[0110] Element C H S N O <![CDATA[H2O]]> Ash content / % 67.62 4.59 0.67 0.53 5.47 3.54 15.41

[0111] The specifications of the rotary kiln used are The specific process of this embodiment is as follows:

[0112] 1) Pulverized coal preparation

[0113] Raw coal is crushed and ball-milled to 0.2mm to produce pulverized coal. If the raw coal contains more than 8% moisture, dry hot air is introduced during pulverization to reduce the moisture content of the resulting pulverized coal to below 8wt%. In this embodiment, the dry hot air is supplied by a natural gas hot air furnace. The pulverized coal produced by the pulverizer is conveyed by air to a dust collector located at the top of the pulverized coal silo. The pulverized coal is then separated by dust bags and enters the silo, where the gas is discharged into the atmosphere.

[0114] 2) Granulation of ingredients

[0115] Copper smelting slag is crushed and ball-milled to produce copper slag powder with a particle size of less than 40 mesh. The copper slag powder, limestone powder, and pulverized coal are metered by weighing feeders at the bottom of the silo before entering a mixing conveyor. The weight ratio of copper slag powder, limestone powder, and pulverized coal is 100:5:28. The materials on the mixing conveyor enter a twin-shaft mixer for uniform mixing. During the mixing process, liquid and / or solid adhesives are added, and water is added to achieve a moisture content of 4wt%.

[0116] The evenly mixed material is added to the roller granulator and pressed into spherical or / and ellipsoidal pellets with a diameter of 25-35 mm. The pellets should be strong enough to withstand being dropped from a height of 2 m at least twice without breaking. Any material that leaks from the pelletizing process is returned to the twin-shaft mixer via a return conveyor. The pellets are then fed to the rotary kiln via a conveyor belt.

[0117] 3) Solid-state reduction

[0118] Pellets are fed into the rotary kiln from the rear via a conveyor belt. Air is forced into the kiln head, providing oxygen for combustion, ensuring full combustion of the pulverized coal in the pellets and creating a strong reducing atmosphere. The reduction temperature is 1100-1200°C, and the pellets remain solid. Zinc, lead, and cadmium are reduced to metals, which evaporate into metal vapor at high temperatures and enter the flue gas. Oxidation in the flue gas produces metal oxides, which accumulate in the dust collector, resulting in secondary zinc oxide. The flue gas, after dust collection, enters the scrubber for desulfurization and meets emission standards. The iron oxide component in the pellets is reduced to elemental iron, which enters the cooling drum along with the reduced material.

[0119] 4) Cooling ball mill

[0120] The reduced material obtained after the rotary kiln reduction is discharged from the rotary kiln head and enters the cooling cylinder for cooling. After cooling, it is sent to the dry ball mill for ball milling until the particle size is less than 80 mesh to obtain the reduced powder.

[0121] 5) Magnetic separation

[0122] The reduced powder is subjected to three-stage magnetic separation using a roller dry magnetic separator under weak magnetic field conditions (current 0.4A, magnetic field 1500Oe, magnetic plate spacing 4mm) to produce iron powder products and tailings.

[0123] 6) Tailings flotation

[0124] The tailings are slurried, subjected to one roughing and one sweeping process, to produce carbon powder and tailings. The carbon powder can be returned as pulverized coal ingredients, and the tailings can be sold as building materials.

[0125] The output products of this embodiment are as follows:

[0126] Iron powder: main grade iron content: 91.76%, iron recovery rate: 89.15%;

[0127] Carbon powder: main grade carbon content: 72.62%, carbon recovery rate: 68.39%;

[0128] Secondary zinc oxide powder in smoke: contains 31.78% zinc, 11.65% lead, and the recovery rate of zinc and lead is >95%.

[0129] The unit consumption indicators of this embodiment are: coal consumption 197.17 kg / t slag, limestone powder consumption 46.73 kg / t slag, binder consumption 31.63 kg / t slag, electricity consumption 169.64 kwh / t slag, and water consumption 0.94 t / t slag.

[0130] The process of this embodiment has large processing capacity, low consumption, high recovery rate, and is suitable for large-scale industrial production.

Claims

1. A method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln, characterized in that: Copper slag powder is obtained by crushing copper smelting slag; pellets containing the copper slag powder are solid-state reduced at 1100°C to 1200°C in a rotary kiln; the resulting reduced material is subjected to magnetic separation to obtain iron powder and tailings; The pellets are fed into the rotary kiln from the rear of the rotary kiln, air is blown into the kiln head, and the reduced materials are discharged from the kiln head; The raw materials of the pellets include copper slag powder, limestone powder and pulverized coal; the weight ratio of the copper slag powder, limestone powder and pulverized coal is 100:3-15:20-40.

2. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1, characterized in that: The diameter of the pellets is 25 to 35 mm.

3. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1, characterized in that: The copper content in the copper smelting slag is less than 0.5 wt %; the iron content in the copper smelting slag is 30 wt % to 60 wt %.

4. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1, characterized in that: The particle size of the copper slag powder is less than 40 mesh; the particle size of the pulverized coal is 0.1-0.5 mm; and the moisture content of the pulverized coal is less than 8 wt%.

5. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1, characterized in that: The weight ratio of the copper slag powder, limestone powder and pulverized coal is 100:5-12:25-35.

6. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1, characterized in that: The pellets must be strong enough to withstand being dropped from a height of 2 m for more than two times without breaking.

7. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to any one of claims 1 to 6, characterized in that: The method for making the pellets comprises: uniformly mixing raw materials and a binder, controlling the moisture content to be 4wt% to 6wt%, and extruding the mixture.

8. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1, characterized in that: Before the magnetic separation, the reduced material is crushed to a particle size of less than or equal to 80 meshes.

9. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to claim 1 or 8, characterized in that: The tailings are slurried and then subjected to flotation to produce carbon powder and tailings.

10. The method for producing iron powder by solid-state reduction treatment of copper smelting slag in a rotary kiln according to any one of claims 1 to 6, characterized in that: The flue gas in the solid-state reduction process is collected and the dust is collected to obtain the metal oxide product.

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