System and method for cooperatively recovering iron and copper from copper smelting slag by dry method

Abstract

The application provides a system and method for cooperatively recovering iron and copper in copper smelting slag by dry method, and belongs to the technical field of mineral processing and metallurgy. The system for cooperatively recovering iron and copper in copper smelting slag by dry method comprises a high-pressure roller mill (1), a ball mill (2), a feeding belt (3), a screw feeder (4), a cyclone preheater (5), a suspension reduction roaster (6), a cyclone separator (7), a cooler (8), a low-intensity magnetic separator (9), a concentrate collecting bin (10), a tailing collecting bin (11), a dust collector (12), an induced draft fan (13) and a dust hopper (14). The method for cooperatively recovering iron and copper in copper smelting slag by dry method adopts the above system, and the whole process is dry reduction and magnetic separation, so that the synchronous recovery of copper and iron in copper slag can be efficiently realized. Compared with the traditional wet process, the use of reagents and the discharge of sewage are avoided, and the beneficial effects of green, environmental protection and energy saving are achieved.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and metallurgical technology, and specifically relates to a system and method for the dry recovery of iron and copper synergistically from copper smelting slag. Background Technology

[0002] Copper smelting processes produce a large amount of copper smelting slag, with approximately 2.2 tons of slag produced for every ton of copper produced. The main components of copper smelting slag are amorphous glassy particles composed of fir olivine, magnetite, copper sulfide, copper oxide, and some gangue, generally containing about 40% iron and 1% copper. Currently, my country faces a severe shortage of iron ore resources, with an import dependency rate as high as 65%, making self-sufficiency difficult and posing a significant challenge to the steel industry, a pillar of the nation's economy. With the development of smelting technology, copper-iron alloys can serve as ideal raw materials for steelmaking. Adding an appropriate amount of copper to steelmaking can improve the quality of steel products, enhance their weather resistance and antibacterial properties, and result in steel products with good weather resistance and excellent mechanical and weldability properties. Therefore, simultaneously extracting iron and copper from copper smelting slag to obtain copper-iron alloys for use in steelmaking can not only achieve efficient utilization of copper slag resources but also promote the sustainable development of the steel industry.

[0003] Currently, research on the recovery of valuable metals from copper slag mainly focuses on single metals, such as pure copper concentrate and iron concentrate. Patent CN201621248719.8 discloses a grinding and magnetic separation system for copper slag, combining a rotary hearth furnace and grinding and magnetic separation equipment. The copper slag is reduced by pelletizing before grinding and magnetic separation to achieve the recovery of iron and zinc. This system has a large processing capacity and a simple operation process; however, it generates flue gas during the process, causing environmental pollution. Patent CN202222971299.8 discloses a device for extracting iron from copper smelting slag, using a combination of a rotary hearth furnace and dry and wet grinding and magnetic separation equipment to fully magnetically separate copper smelting slag of different particle sizes, improving the iron recovery rate; however, this process is complex, has a limited processing capacity, and has certain limitations in engineering applications. Furthermore, wet magnetic separation generates a large amount of water, which is detrimental to resource conservation and environmental protection. Patent CN202111116502.7 discloses a method and smelting apparatus for producing crude copper by smelting copper slag. By combining oxygen-enriched top blowing and side blowing smelting technologies, copper and lead are separated. This method has high separation efficiency and good metal recovery rate. However, the use of soda ash reagent and the need to add fuel during the smelting process increase the process cost to some extent.

[0004] In summary, the recovery of valuable metals from copper smelting slag still faces many challenges, and only a single type of metal, iron, can be recovered. Developing a system that enables the green, environmentally friendly, and efficient simultaneous recovery of iron and copper from copper smelting slag will help further improve the efficiency of simultaneous extraction of valuable metals iron and copper from copper smelting slag, realizing the high-value-added utilization of copper smelting slag as a secondary resource. Summary of the Invention

[0005] To address the problems of complex processes, limited product selection, large equipment footprint, high energy consumption, and environmental pollution associated with existing copper smelting slag recovery technologies, this invention provides a system for the co-process dry recovery of iron and copper from copper smelting slag. This system achieves precise reduction, efficient iron extraction, and efficient simultaneous recovery of iron and copper from copper smelting slag.

[0006] A system for the dry recovery of iron and copper from copper smelting slag includes a high-pressure roller mill (1), a ball mill (2), a feeding belt (3), a screw feeder (4), a cyclone preheater (5), a suspension reduction roasting furnace (6), a cyclone separator (7), a cooler (8), a weak magnetic separator (9), a concentrate collection bin (10), a tailings collection bin (11), a dust collector (12), an induced draft fan (13), and an ash hopper (14).

[0007] The discharge port of the high-pressure roller mill (1) is connected to the feed port of the ball mill (2). The discharge port of the ball mill (2) is connected to the feed port of the screw feeder (4) via the feeding belt (3). The discharge port of the screw feeder (4) is connected to the cyclone preheater (5). The upper air outlet of the cyclone preheater (5) is connected to the dust collector (12). The air outlet of the dust collector (12) is connected to the air inlet of the induced draft fan (13). The lower discharge port of the ) is connected to the feed port at the top of the suspension reduction roasting furnace (6), and the discharge port on the side of the suspension reduction roasting furnace (6) is connected to the feed port of the cyclone separator (7); the discharge port of the cyclone separator (7) is connected to the cooler (8), the cooler (8) is connected to the weak magnetic separator (9), the concentrate outlet of the weak magnetic separator (9) is connected to the concentrate collection bin (10), and the tailings outlet of the weak magnetic separator (9) is connected to the tailings collection bin (11).

[0008] Furthermore, the air outlet of the cyclone separator (7) is connected to the dust collector (12), and the discharge outlet of the dust collector (12) is connected to the ash hopper (14).

[0009] Furthermore, the suspension reduction roasting furnace (6) has a material reduction reaction chamber, and a bottom plate is provided below the reduction reaction chamber. The bottom plate is provided with a reducing gas inlet, which is opposite to the material reduction reaction chamber.

[0010] Furthermore, the cyclone separator (7) is provided with an external heat insulation layer.

[0011] Furthermore, the cyclone preheater (5), the suspension reduction roasting furnace (6), the cyclone separator (7), and the cooler (8) are equipped with temperature sensors and pressure sensors.

[0012] Furthermore, the ball mill (2) includes overflow type and grid type ball mills.

[0013] A method for the co-harvesting dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-harvesting dry recovery of iron and copper from copper smelting slag, is carried out according to the following steps:

[0014] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder. The portion of the copper slag powder with a particle size of -0.074mm accounts for ≥80% of the total mass. It is then conveyed to a screw feeder (4) via a feeding belt (3). The iron content of the copper smelting slag is 30% to 50%, and the copper content is 0.5% to 3%.

[0015] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0016] Step 3: The copper slag powder in the screw feeder 4 is conveyed to the cyclone preheater 5. Under the action of the cyclone preheater, the copper smelting slag removes moisture, increases the heat storage temperature, and forms preheated powder.

[0017] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace 6 to purge the air, and then reducing gas is introduced. The preheated powder is introduced into the suspension reduction roasting furnace 6 for suspension roasting. The preheated powder is kept in a fluidized state under the reducing atmosphere, thereby improving the reduction reaction efficiency. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (7) with the airflow.

[0018] The reaction equation involved in the reduction reaction is:

[0019] 3Fe2O3(s)+CO / H2(g)=2Fe3O4(s)+CO2 / H2O (g) (1)

[0020] Fe3O4(s)+CO / H2 (g)=3FeO(s)+ CO2 / H2O (g) (2)

[0021] FeO(s)+CO / H2 (g)=Fe(s)+ CO2 / H2O (g) (3)

[0022] 2FeO·SiO2(s)+2CO / H2 (g)=2Fe(s)+SiO2(s)+2CO2 / H2O (g) (4)

[0023] FeAl2O4(s)+CO / H2 (g)=Fe(s)+Al2O3(s)+ CO2 / H2O (g) (5)

[0024] FeO·SiO2(s)+CO / H2 (g)=Fe(s)+SiO2(s)+ CO2 / H2O (g) (6)

[0025] CuO(s)+CO / H2 (g)=Cu+ CO2 / H2O (g) (7)

[0026] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 1 to 5 minutes. The purified reduced product is then passed into the cooler 8 and cooled down by heat exchange to form a cooled product with a temperature ≤100℃.

[0027] Step 6: Feed the cooled product into a dry weak magnetic separator with a magnetic field strength of 80-180 kA / m, and obtain magnetic concentrate through magnetic separation.

[0028] Furthermore, the temperature of the preheated copper slag powder in step (3) is 200-350℃, and the preheating time is 10-15 min.

[0029] Further, the reducing gas in step (4) is prepared by mixing H2 and / or CO produced by coal gasification or natural gas cracking with nitrogen; the volume percentage of N2 in the reducing gas is 45-65%; the amount of reducing gas used is 1:1 to 1.2 times the theoretical amount of CO / H2 required for complete reduction roasting reaction.

[0030] Furthermore, the reaction temperature of the preheated powder in step (4) in the suspension reduction calcination furnace is 600-1200℃, and the reaction time is 30-60min.

[0031] Furthermore, in step (6), the magnetic concentrate contains an iron grade of ≥70% and a recovery rate of ≥85%; and a copper grade of ≥5% and a recovery rate of ≥80%.

[0032] In this invention, the copper slag contains a large amount of ferrosilicon, magnetic iron, primary copper minerals, and secondary copper minerals. After crushing, grinding, and granulation, it has a certain oxygen-releasing capacity. The particles are preheated and heated in a suspension roasting furnace to reach a certain temperature. Under regenerative and fluid conditions, they come into contact with reducing gases and undergo a staged reaction in the order of Fe2O3→Fe3O4→FeO→Fe and CuO→Cu. The material after reduction roasting is separated, purified, and then cooled. During this stage, the phase composition does not change. After magnetic separation, copper and iron concentrates are separated, ensuring both grade and recovery rate while meeting smelting requirements.

[0033] The beneficial effects of this invention are as follows: Compared with conventional flotation and magnetic separation staged recovery processes, it can efficiently achieve simultaneous recovery of copper and iron from copper slag; the use of gas-based suspension roasting keeps mineral particles in a suspended state in the fluidized bed, increasing the gas-solid reaction contact area, improving reaction efficiency, achieving efficient reduction, and precise control; the entire process is dry reduction and magnetic separation, which avoids the use of reagents and wastewater discharge compared with traditional wet processes, achieving the beneficial effects of being green, environmentally friendly, and energy-saving. Attached Figure Description

[0034] Figure 1 A system for the dry co-process recovery of iron and copper from copper smelting slag;

[0035] In the diagram, 1. High-pressure roller mill, 2. Ball mill, 3. Feed belt, 4. Screw feeder, 5. Cyclone preheater, 6. Suspension reduction roasting furnace, 7. Cyclone separator, 8. Cooler, 9. Weak magnetic separator, 10. Concentrate collection bin, 11. Tailings collection bin, 12. Dust collector, 13. Exhaust fan, 14. Ash hopper. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] A system for the co-process dry recovery of iron and copper from copper smelting slag, such as Figure 1 As shown, it includes a high-pressure roller mill (1), a ball mill (2), a feeding belt (3), a screw feeder (4), a cyclone preheater (5), a suspension reduction roasting furnace (6), a cyclone separator (7), a cooler (8), a weak magnetic separator (9), a concentrate collection bin (10), a tailings collection bin (11), a dust collector (12), an induced draft fan (13), and an ash hopper (14).

[0038] The discharge port of the high-pressure roller mill (1) is connected to the feed port of the ball mill (2). The discharge port of the ball mill (2) is connected to the feed port of the screw feeder (4) through the feeding belt (3). The discharge port of the screw feeder (4) is connected to the cyclone preheater (5).

[0039] The upper air outlet of the cyclone preheater (5) is connected to the dust collector (12), and the air outlet of the dust collector (12) is connected to the air inlet of the induced draft fan (13).

[0040] The lower outlet of the cyclone preheater (5) is connected to the top inlet of the suspension reduction roasting furnace (6), and the side outlet of the suspension reduction roasting furnace (6) is connected to the inlet of the cyclone separator (7).

[0041] The discharge port of the cyclone separator (7) is connected to the cooler (8), the cooler (8) is connected to the weak magnetic separator (9), the concentrate outlet of the weak magnetic separator (9) is connected to the concentrate collection bin (10), and the tailings outlet of the weak magnetic separator (9) is connected to the tailings collection bin (11).

[0042] In the system, the outlet of the cyclone separator (7) is connected to the outlet (4) of the screw feeder.

[0043] In the system, the discharge port of the dust collector (12) is matched with the ash hopper (14).

[0044] In the system, the suspension reduction roasting furnace (6) has a material reduction reaction chamber. The material reduction reaction chamber has a bottom plate below it, and the bottom plate is provided with nitrogen and reducing gas inlets, which are opposite to the material reduction reaction chamber.

[0045] In the system, the cyclone separator (7) is provided with an insulation layer on the outside.

[0046] In the system, temperature sensors and pressure sensors are installed inside the cyclone preheater (5), the suspension reduction roasting furnace (6), the cyclone separator (7), and the cooler (8).

[0047] Example 1

[0048] A method for the co-harvesting dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-harvesting dry recovery of iron and copper from copper smelting slag, includes the following specific operating steps:

[0049] The main components of the copper smelting slag used in this embodiment are Fe2O3 38.77%, SiO2 12.92%, ZnO 11.24%, CaO 13.11%, Al2O3 4.46%, and CuO 0.78%.

[0050] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder, which is then conveyed to a screw feeder (4) via a feeding belt (3); the portion of the copper slag powder with a particle size of -0.074mm accounts for 85% of the total mass.

[0051] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0052] Step 3: The copper slag powder in the screw feeder (4) is transported together with the hot air separated in the cyclone separator (7) to the cyclone preheater (5) and preheated at 250°C for 10 minutes to remove moisture and form preheated powder.

[0053] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air. Then, reducing gas is introduced at a ratio of 1:1 to the theoretical amount of CO / H2 required for complete reduction roasting. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The roasting temperature is set to 650°C by the temperature control device. The preheated material is roasted for 30 minutes in a reducing atmosphere containing 45% N2 by volume. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow.

[0054] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 3 minutes. The purified reduced product is then passed into the cooler (8) and cooled to 100°C to obtain the cooled product.

[0055] Step 6: Feed the cooled product into the dry weak magnetic separator (9). The magnetic field strength of the dry weak magnetic separator is 100kA / m. Magnetic concentrate is obtained after magnetic separation.

[0056] The magnetic separation concentrate contained 82.43% iron with a recovery rate of 90.24% and 5.21% copper with a recovery rate of 87.89%.

[0057] Example 2

[0058] A method for the co-harvesting dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-harvesting dry recovery of iron and copper from copper smelting slag, includes the following specific operating steps:

[0059] The main components of the copper smelting slag used in this embodiment are Fe2O3 42.34%, SiO2 10.41%, ZnO 12.13%, CaO 11.22%, Al2O3 3.88%, and CuO 1.43%.

[0060] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder, which is then conveyed to a screw feeder (4) via a feeding belt (3); the portion of the copper slag powder with a particle size of -0.074mm accounts for 90% of the total mass.

[0061] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0062] Step 3: The copper slag powder in the screw feeder (4) is transported together with the hot air separated in the cyclone separator (7) to the cyclone preheater (5) and preheated at 300℃ for 12 minutes to remove moisture and form preheated powder.

[0063] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air. Then, reducing gas is introduced at a ratio of 1:15 to the theoretical amount of CO / H2 required for complete reduction roasting. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The roasting temperature is set to 800℃ by the temperature control device. The preheated material is roasted for 40 minutes in a reducing atmosphere containing 50% N2 by volume. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow.

[0064] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 4 minutes. The purified reduced product is then passed into the cooler (8) and cooled to 80°C to obtain the cooled product.

[0065] Step 6: Feed the cooled product into the dry weak magnetic separator (9). The magnetic field strength of the dry weak magnetic separator is 130kA / m. Magnetic concentrate is obtained after magnetic separation.

[0066] The magnetic separation concentrate contained 86.78% iron with a recovery rate of 89.11% and 6.43% copper with a recovery rate of 85.22%.

[0067] Example 3

[0068] A method for the co-harvesting dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-harvesting dry recovery of iron and copper from copper smelting slag, includes the following specific operating steps:

[0069] The main components of the copper smelting slag used in this embodiment are Fe2O3 45.25%, SiO2 8.36%, ZnO 9.27%, CaO 12.03%, Al2O3 4.21%, and CuO 1.89%.

[0070] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder, which is then conveyed to a screw feeder (4) via a feeding belt (3); the portion of the copper slag powder with a particle size of -0.074mm accounts for 95% of the total mass.

[0071] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0072] Step 3: The copper slag powder in the screw feeder (4) is transported together with the hot air separated in the cyclone separator (7) to the cyclone preheater (5) and preheated at 350°C for 15 minutes to remove moisture and form preheated powder.

[0073] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air. Then, the amount of reducing gas is introduced at 1:2 times the theoretical amount of CO / H2 required for complete reduction roasting. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The roasting temperature is set to 1100℃ by the temperature control device. The preheated material is roasted for 50 minutes in a reducing atmosphere containing 55% N2 by volume. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow.

[0074] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 5 minutes. The purified reduced product is then passed into the cooler (8) and cooled to 75°C to obtain the cooled product.

[0075] Step 6: Feed the cooled product into the dry weak magnetic separator (9). The magnetic field strength of the dry weak magnetic separator is 150kA / m. Magnetic concentrate is obtained after magnetic separation.

[0076] The magnetic separation concentrate contained 90.21% iron with a recovery rate of 88.44% and 6.71% copper with a recovery rate of 84.96%.

[0077] Example 4

[0078] A method for the co-process dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-process dry recovery of iron and copper from copper smelting slag, includes the following specific operating steps:

[0079] The main components of the copper smelting slag used in this embodiment are Fe2O3 45.25%, SiO2 8.36%, ZnO 9.27%, CaO 12.03%, Al2O3 4.21%, and CuO 1.89%.

[0080] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder, which is then conveyed to a screw feeder (4) via a feeding belt (3); the portion of the copper slag powder with a particle size of -0.074mm accounts for 90% of the total mass.

[0081] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0082] Step 3: The copper slag powder in the screw feeder (4) is transported together with the hot air separated in the cyclone separator (7) to the cyclone preheater (5) and preheated at 300°C for 10 minutes to remove moisture and form preheated powder.

[0083] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air. Then, reducing gas is introduced at a ratio of 1:2 to the theoretical amount of CO / H2 required for complete reduction roasting. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The roasting temperature is set to 1050℃ by the temperature control device. The preheated material is roasted for 40 minutes in a reducing atmosphere containing 55% N2 by volume. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow.

[0084] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 5 minutes. The purified reduced product is then passed into the cooler (8) and cooled to 75°C to obtain the cooled product.

[0085] Step 6: Feed the cooled product into the dry weak magnetic separator (9). The magnetic field strength of the dry weak magnetic separator is 150kA / m. Magnetic concentrate is obtained after magnetic separation.

[0086] The magnetic separation concentrate contained 91.45% iron with a recovery rate of 86.26% and 5.65% copper with a recovery rate of 82.36%.

[0087] Example 5

[0088] A method for the co-process dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-process dry recovery of iron and copper from copper smelting slag, includes the following specific operating steps:

[0089] The main components of the copper smelting slag used in this embodiment are Fe2O3 41.85%, SiO2 12.74%, ZnO 9.27%, CaO 10.15%, Al2O3 5.32%, and CuO 2.71%.

[0090] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder, which is then conveyed to a screw feeder (4) via a feeding belt (3); the portion of the copper slag powder with a particle size of -0.074mm accounts for 95% of the total mass.

[0091] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0092] Step 3: The copper slag powder in the screw feeder (4) is transported together with the hot air separated in the cyclone separator (7) to the cyclone preheater (5) and preheated at 250°C for 15 minutes to remove moisture and form preheated powder.

[0093] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air. Then, reducing gas is introduced at a ratio of 1:2 to the theoretical amount of CO / H2 required for complete reduction roasting. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The roasting temperature is set to 1150℃ by the temperature control device. The preheated material is roasted for 45 minutes in a reducing atmosphere containing 45% N2 by volume. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow.

[0094] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 1 minute. The purified reduced product is then passed into the cooler (8) and cooled to 55°C to obtain the cooled product.

[0095] Step 6: Feed the cooled product into the dry weak magnetic separator (9). The magnetic field strength of the dry weak magnetic separator is 150kA / m. Magnetic concentrate is obtained after magnetic separation.

[0096] The magnetic separation concentrate contained 88.32% iron with a recovery rate of 90.56% and 5.26% copper with a recovery rate of 85.84%.

[0097] Example 6

[0098] A method for the co-process dry recovery of iron and copper from copper smelting slag, employing the aforementioned system for the co-process dry recovery of iron and copper from copper smelting slag, includes the following specific operating steps:

[0099] The main components of the copper smelting slag used in this embodiment are Fe2O3 48.52%, SiO2 10.52%, ZnO 10.35%, CaO 10.01%, Al2O3 6.21%, and CuO 2.73%.

[0100] Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for fine grinding to form copper slag powder, which is then conveyed to a screw feeder (4) via a feeding belt (3); the portion of the copper slag powder with a particle size of -0.074mm accounts for 95% of the total mass.

[0101] Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7);

[0102] Step 3: The copper slag powder in the screw feeder (4) is transported together with the hot air separated in the cyclone separator (7) to the cyclone preheater (5) and preheated at 350°C for 5 minutes to remove moisture and form preheated powder.

[0103] Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air. Then, reducing gas is introduced at a ratio of 1:2 to the theoretical amount of CO / H2 required for complete reduction roasting. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The roasting temperature is set to 1000℃ by the temperature control device. The preheated material is roasted for 30 minutes in a reducing atmosphere containing 50% N2 by volume. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow.

[0104] Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 1 minute. The purified reduced product is then passed into the cooler (8) and cooled to 75°C to obtain the cooled product.

[0105] Step 6: Feed the cooled product into the dry weak magnetic separator (9). The magnetic field strength of the dry weak magnetic separator is 150kA / m. Magnetic concentrate is obtained after magnetic separation.

[0106] The magnetic separation concentrate had an iron grade of 91.42% and a recovery rate of 89.75%; and a copper grade of 5.95% and a recovery rate of 86.52%.

Claims

1. A method for the co-process dry recovery of iron and copper from copper smelting slag, characterized in that, A system for the dry recovery of iron and copper from copper smelting slag using a co-process method is adopted. The system includes a high-pressure roller mill (1), a ball mill (2), a feeding belt (3), a screw feeder (4), a cyclone preheater (5), a suspension reduction roasting furnace (6), a cyclone separator (7), a cooler (8), a weak magnetic separator (9), a concentrate collection bin (10), a tailings collection bin (11), a dust collector (12), an induced draft fan (13), and an ash hopper (14). The discharge port of the high-pressure roller mill (1) is connected to the inlet of the ball mill (2), the discharge port of the ball mill (2) is connected to the inlet of the screw feeder (4) via the feeding belt (3), and the discharge port of the screw feeder (4) is connected to... The cyclone preheater (5) is connected; the upper air outlet of the cyclone preheater (5) is connected to the dust collector (12), and the air outlet of the dust collector (12) is connected to the air inlet of the induced draft fan (13); the lower discharge port of the cyclone preheater (5) is connected to the top feed port of the suspension reduction roasting furnace (6), and the discharge port on the side of the suspension reduction roasting furnace (6) is connected to the feed port of the cyclone separator (7); the discharge port of the cyclone separator (7) is connected to the cooler (8), the cooler (8) is connected to the weak magnetic separator (9), the concentrate outlet of the weak magnetic separator (9) is connected to the concentrate collection bin (10), and the tailings outlet of the weak magnetic separator (9) is connected to the tailings collection bin (11). The suspension reduction roasting furnace (6) has a material reduction reaction chamber, and a bottom plate is provided below the reduction reaction chamber. The bottom plate is provided with a reducing gas inlet, which is opposite to the material reduction reaction chamber. The method is performed according to the following steps: Step 1: The copper smelting slag is pre-ground by a high-pressure roller mill (1), and then fed into a ball mill (2) for further grinding to form copper slag powder. The portion of the copper slag powder with a particle size of -0.074mm accounts for ≥80% of the total mass. It is then conveyed to a screw feeder (4) via a feeding belt (3). The iron content of the copper smelting slag is 30%~50%, and the copper content is 0.5%~3%. Step 2: Start the induced draft fan (13) to create negative pressure in the dust collector (12), cyclone preheater (5), suspension reduction roasting furnace (6) and cyclone separator (7); Step 3: The copper slag powder in the screw feeder (4) is transported to the cyclone preheater (5). Under the action of the cyclone preheater, the copper smelting slag removes moisture, increases the heat storage temperature, and forms preheated powder. The preheating temperature of the copper slag powder in step 3 is 200℃~350℃, and the preheating time is 10min~15min; Step 4: Nitrogen gas is introduced into the suspension reduction roasting furnace (6) to purge the air, and then reducing gas is introduced. The preheated powder is introduced into the suspension reduction roasting furnace (6) for suspension roasting. The preheated powder is kept in a fluidized state under the reducing atmosphere, thereby improving the reduction reaction efficiency. The generated reduced product is discharged from the outlet of the suspension reduction roasting furnace (6) with the airflow. The reaction equation involved in the reduction reaction is: 3Fe2O3(s)+CO / H2(g)=2Fe3O4(s)+CO2 / H2O(g) (1) Fe3O4(s)+CO / H2(g)=3FeO(s)+CO2 / H2O(g) (2) FeO(s)+CO / H2(g)=Fe(s)+CO2 / H2O(g)(3) 2FeO·SiO2(s)+2CO / H2(g)=2Fe(s)+SiO2(s)+2CO2 / H2O(g) (4) FeAl2O4(s)+CO / H2(g)=Fe(s)+Al2O3(s)+CO2 / H2O(g)(5) FeO·SiO2(s)+CO / H2(g)=Fe(s)+SiO2(s)+CO2 / H2O(g) (6) CuO(s)+CO / H2(g)=Cu+CO2 / H2O(g)(7); The reducing gas mentioned in step 4 is prepared by mixing H2 and / or CO produced by coal gasification or natural gas cracking with nitrogen; the volume percentage of N2 in the reducing gas is 45-65%; the amount of reducing gas used is 1:1 to 1.2 times the theoretical amount of CO / H2 required for complete reduction roasting reaction; The reaction temperature of the preheated powder in step 4 in the suspension reduction calcination furnace is 600~1200℃, and the reaction time is 30~60min; Step 5: The reduced product discharged from the outlet of the suspension reduction roasting furnace (6) enters the cyclone separator (7) for gas-solid separation for 1~5 minutes. The purified reduced product is then passed into the cooler (8) and cooled down by heat exchange to form a cooled product with a temperature ≤100℃. Step 6: Feed the cooled product into a dry weak magnetic separator with a magnetic field strength of 80-180 kA / m, and obtain magnetic concentrate through magnetic separation.

2. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The outlet of the cyclone separator (7) is connected to the dust collector (12), and the outlet of the dust collector (12) is connected to the ash hopper (14).

3. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The cyclone separator (7) is provided with an external heat insulation layer.

4. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, Temperature sensors and pressure sensors are installed inside the cyclone preheater (5), suspension reduction roasting furnace (6), cyclone separator (7), and cooler (8).

5. The method for co-processing dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The magnetic separation concentrate described in step 6 has an iron grade of ≥70% and a recovery rate of ≥85%; and a copper grade of ≥5% and a recovery rate of ≥80%.

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