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

Abstract

The application provides a method for cooperatively recovering iron and copper in copper smelting slag by dry method and belongs to the field of mining engineering. The suspension roasting technology is applied to synchronous extraction of valuable metals in the copper smelting slag, so that a large number of iron and copper compounds contained in the copper smelting slag are subjected to phase transformation and valuable extraction. After the copper smelting slag is crushed, ground, granulated, subjected to classification reduction through suspension roasting, and subjected to magnetic separation, high-grade iron and copper concentrates are obtained, and high-value comprehensive utilization of the copper smelting slag is realized.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering, and specifically relates to a dry method for the co-process recovery of iron and copper from copper smelting slag. Background Technology

[0002] With technological advancements, the production and consumption of copper resources are increasing. my country is a major consumer of copper resources, but due to its relatively poor domestic copper endowment and high mining and utilization costs, it suffers from a severe dependence on imports. Therefore, how to effectively utilize domestic copper resources is an urgent issue. Pyrometallurgical copper smelting processes generate a large amount of waste slag; currently, the accumulated copper smelting slag reaches 50 million tons. Copper smelting slag generally still contains about 0.5% copper, in addition to about 20-50% iron, far exceeding the exploitable grades of copper and iron ores in my country. Furthermore, copper slag contains large amounts of valuable elements such as nickel, cobalt, and zinc. Utilizing and recovering these resources, including iron and copper, can not only create substantial economic benefits and alleviate my country's dependence on imports of strategic metals, but more importantly, it can achieve comprehensive utilization of secondary resources, contributing to the further development of my country's ecological environmental protection.

[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 CN201710152577.8 discloses a method for directly reducing and recovering iron from copper smelting slag. After modification, the copper smelting slag is directly reduced using coal, achieving effective recovery of iron from copper smelting slag. However, the use of coal-based reduction has certain problems such as high infrastructure costs and environmental pollution. It also requires the installation of pulverized coal injection equipment, making the process complex. Furthermore, this method uses rotary kiln reduction, which has limited processing capacity and high equipment costs. Patent CN202010670813.7 discloses a method for comprehensive recovery of multiple metals from copper smelting slag. The specific scheme involves mixing copper smelting slag with microwave absorbing material and then microwave roasting it. The roasting fumes are lead-zinc products. The roasted slag is magnetically separated to obtain iron-containing products. The tailings from the magnetic separation are floated to obtain silicon-containing materials and copper-antimony products. This method recovers a large amount of metals, but the process is complicated, costly, and pollutes the environment with flotation reagents. In addition, the recovered materials contain a lot of by-products, which still need to be further separated.

[0004] It is evident that there are still many problems in the comprehensive treatment and utilization of copper smelting slag resources. Most processes are cumbersome, the recovered products are limited, and the treatment rate is low. Therefore, this invention addresses these problems in copper smelting slag recycling by proposing a dry method for the synergistic recovery of iron and copper from copper smelting slag, thereby achieving comprehensive recycling and utilization of copper smelting slag. Summary of the Invention

[0005] To address the existing technical problems in the comprehensive utilization of copper smelting slag, this invention aims to provide a dry method for the synergistic recovery of iron and copper from copper smelting slag, enabling the phase transformation and valuable extraction of the large amount of iron and copper compounds present in the slag. After crushing, grinding, and granulation, the copper smelting slag undergoes staged reduction via suspension roasting, followed by magnetic separation to simultaneously obtain high-grade iron and copper concentrates, achieving high-value-added comprehensive utilization of the copper smelting slag.

[0006] The present invention discloses a method for the co-process dry recovery of iron and copper from copper smelting slag, the specific steps of which are as follows:

[0007] Step 1: Crushing and grinding: The copper smelting slag is crushed and ground until the portion with a particle size of -0.074mm accounts for ≥85% of the total mass, and then made into powder.

[0008] Step 2: Preheating and dehydration: The powder is preheated at a temperature of 200-350°C for 10-15 minutes to obtain preheated powder.

[0009] Step 3: Reduction calcination: The preheated powder is fed into a suspension reduction calcination furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeding device. The reduction reaction device is connected to the gas feeding device at the bottom. Nitrogen and reducing gas are introduced through the gas feeding device, and the calcination temperature is adjusted by the temperature control device to reduce and calcinate the preheated powder in a suspended state to obtain the reduced product.

[0010] The reaction equations that may be involved in the reduction roasting process are:

[0011] 3Fe2O3(s)+CO / H2(g)=2Fe3O4(s)+CO2 / H2O(g) (1)

[0012] Fe3O4(s)+CO / H2(g)=3FeO(s)+CO2 / H2O(g) (2)

[0013] FeO(s)+CO / H2(g)=Fe(s)+CO2 / H2O(g) (3)

[0014] 2FeO·SiO2(s)+2CO / H2(g)=2Fe(s)+SiO2(s)+2CO2 / H2O(g) (4)

[0015] FeAl2O4(s)+CO / H2(g)=Fe(s)+Al2O3(s)+CO2 / H2O(g) (5)

[0016] FeO·SiO2(s)+CO / H2(g)=Fe(s)+SiO2(s)+CO2 / H2O(g) (6)

[0017] CuO(s)+CO / H2(g)=Cu+CO2 / H2O(g) (7)

[0018] Step 4: Purification and Cooling: The reduced product is subjected to cyclone gas-solid separation to obtain purified solid particles, which are then cooled to obtain cooled material.

[0019] Step 5: Perform dry weak magnetic separation on the cooled material to obtain iron and copper magnetic concentrate.

[0020] Furthermore, the copper smelting slag described in step 1 contains 30% to 50% iron and 0.5% to 3% copper.

[0021] Furthermore, the reducing gas mentioned in step 3 is H2 and / or CO produced by coal gasification or natural gas cracking.

[0022] Furthermore, the volume percentage of N2 mentioned in step 3 is 45-65%; the amount of reducing gas used is 1.1-1.2 times the theoretical amount of CO / H2 required for complete reduction roasting reaction.

[0023] Furthermore, in step 3, the reaction temperature of the preheated powder in the suspension reduction calcination furnace is 600–1100°C, and the reaction time is 30–60 min.

[0024] Furthermore, the purification time of the reduced product in step 4 is 3 to 6 minutes.

[0025] Furthermore, the discharge temperature of the cooled material described in step 4 is ≤100℃.

[0026] Furthermore, the magnetic field strength of the dry weak magnetic separator described in step 5 is 80–180 kA / m.

[0027] Furthermore, in step 5, the magnetic separation concentrate has an iron grade of ≥70% and a recovery rate of ≥85%; and a copper grade of ≥5% and a recovery rate of ≥80%.

[0028] Compared with existing methods, the features and advantages of this invention are as follows:

[0029] 1. This invention innovatively applies suspension roasting technology to the simultaneous extraction of valuable metals from copper smelting slag. This technology improves the mass transfer efficiency between solid particles and reducing gas, has low energy consumption and low heat loss, realizes the simultaneous reduction of iron and copper in copper smelting slag, optimizes the extraction process, and provides a new approach for the utilization of copper smelting slag.

[0030] 2. This invention adopts a dry process throughout, avoiding the use of chemicals and water pollution, reducing production costs and environmental burden. At the same time, the process flow is short and compact, easy to operate, has low production costs, and is easy to industrialize.

[0031] 3. This invention proposes preheating solid materials before roasting, which provides a certain amount of heat storage energy to the materials themselves while dehydrating and removing impurities, thereby reducing the energy consumption of equipment during further roasting and realizing the high efficiency and multifunctionality of the process.

[0032] 4. This invention combines the advantages of beneficiation and smelting, and after precise control of phase transformation through reduction roasting, it utilizes the magnetic differences of materials for magnetic separation to achieve synergistic recovery of valuable metals, maximizes operational productivity, and achieves efficient utilization of copper smelting slag under low consumption conditions. Attached Figure Description

[0033] Figure 1 This is a process flow diagram of the dry method for co-processing iron and copper recovery from copper smelting slag according to the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments.

[0035] Example 1

[0036] A method for the co-process dry recovery of iron and copper from copper smelting slag, the process flow diagram of which is shown below. Figure 1 The specific operation method is as follows:

[0037] The main components of the copper smelting slag in this embodiment, by mass percentage, are Fe2O3 37.44%, SiO2 11.66%, ZnO 10.47%, CaO 11.15%, Al2O3 3.28%, and CuO 0.64%.

[0038] 1. The portion of copper smelting slag that is crushed and ground to a particle size of -0.074mm accounts for 85% of the total mass, and is then made into powder;

[0039] 2. The powder is preheated to remove internal moisture and increase its heat storage capacity. The preheating temperature is 200℃ and the preheating time is 10 minutes to form preheated powder.

[0040] 3. The preheated powder is fed into a suspension reduction roasting furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeder. The reduction reaction device is connected to the bottom gas feeder. Nitrogen and reducing gas are introduced through the gas feeder, with the volume percentage of N2 in the reducing gas being 45%. The amount of reducing gas used is 1.1 times the theoretical CO / H2 amount required for complete reduction roasting. The roasting temperature is adjusted by the temperature control device, set to 600℃, and the reaction time is 30 minutes to obtain the reduced product.

[0041] 4. The reduced product is subjected to cyclone gas-solid separation with a purification residence time of 3 minutes. The purified solid particles are then cooled to 100°C to obtain cooled material.

[0042] 5. The cooled material is subjected to dry weak magnetic separation. The magnetic field strength of the dry weak magnetic separation is 90kA / m to obtain iron and copper magnetic separation concentrate.

[0043] The iron and copper concentrates contained 76.43% TFe and 4.89% Cu by mass percentage, with recoveries of 92.46% TFe and 85.13% Cu, respectively.

[0044] Example 2

[0045] A method for the co-process dry recovery of iron and copper from copper smelting slag, the process flow diagram of which is shown below. Figure 1 The specific operation method is as follows:

[0046] The main components of the copper smelting slag in this embodiment, by mass percentage, are Fe2O3 40.23%, SiO2 10.26%, ZnO 11.33%, CaO 10.06%, Al2O3 2.47%, and CuO 1.24%.

[0047] 1. The portion of copper smelting slag that is crushed and ground to a particle size of -0.074mm accounts for 85% of the total mass, and is then made into powder;

[0048] 2. The powder is preheated to remove internal moisture and increase its heat storage capacity. The preheating temperature is 260℃ and the preheating time is 10 minutes to form preheated powder.

[0049] 3. The preheated powder is fed into a suspension reduction calcination furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeder. The reduction reaction device is connected to the bottom gas feeder. Nitrogen and reducing gas are introduced through the gas feeder, with the N2 volume percentage in the reducing gas being 50%. The amount of reducing gas used is 1.15 times the theoretical CO / H2 amount required for complete reduction calcination. The calcination temperature is adjusted by the temperature control device, set to 800℃, and the reaction time is 40 minutes to obtain the reduced product.

[0050] 4. The reduced product is subjected to cyclone gas-solid separation with a purification residence time of 4 minutes. The purified solid particles are then cooled to 100°C to obtain cooled material.

[0051] 5. The cooled material is subjected to dry weak magnetic separation. The magnetic field strength of the dry weak magnetic separation is 100kA / m to obtain iron and copper magnetic separation concentrate.

[0052] The iron and copper concentrates contained 78.67% TFe and 5.87% Cu by mass percentage, with recoveries of 89.54% TFe and 84.68% Cu, respectively.

[0053] Example 3

[0054] A method for the co-process dry recovery of iron and copper from copper smelting slag, the process flow diagram of which is shown below. Figure 1 The specific operation method is as follows:

[0055] The main components of the copper smelting slag in this embodiment, by mass percentage, are Fe2O3 42.08%, SiO2 9.66%, ZnO 12.14%, CaO 11.45%, Al2O3 4.13%, and CuO 1.36%.

[0056] 1. The portion of copper smelting slag that is crushed and ground to a particle size of -0.074mm accounts for 90% of the total mass, and is then made into powder;

[0057] 2. The powder is preheated to remove internal moisture and increase its heat storage capacity. The preheating temperature is 280℃ and the preheating time is 12 minutes to form preheated powder.

[0058] 3. The preheated powder is fed into a suspension reduction calcination furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeder. The reduction reaction device is connected to the bottom gas feeder. Nitrogen and reducing gas are introduced through the gas feeder, with the volume percentage of N2 in the reducing gas being 50%. The amount of reducing gas used is 1.2 times the theoretical CO / H2 amount required for complete reduction calcination. The calcination temperature is adjusted by the temperature control device, set to 1000℃, and the reaction time is 50 minutes to obtain the reduced product.

[0059] 4. The reduced product is subjected to cyclone gas-solid separation with a purification residence time of 5 minutes. The purified solid particles are then cooled to 95°C to obtain cooled material.

[0060] 5. The cooled material is subjected to dry weak magnetic separation. The magnetic field strength of the dry weak magnetic separation is 120kA / m to obtain iron and copper magnetic separation concentrate.

[0061] The iron and copper concentrates contained 79.68% TFe and 5.96% Cu by mass percentage, with recoveries of 89.23% TFe and 84.22% Cu, respectively.

[0062] Example 4

[0063] A method for the co-process dry recovery of iron and copper from copper smelting slag, the process flow diagram of which is shown below. Figure 1 The specific operation method is as follows:

[0064] The main components of the copper smelting slag in this embodiment, by mass percentage, are Fe2O3 42.71%, SiO2 10.02%, ZnO 11.23%, CaO 11.31%, Al2O3 3.87%, and CuO 1.67%.

[0065] 1. The portion of copper smelting slag that is crushed and ground to a particle size of -0.074mm accounts for 95% of the total mass, and is then made into powder;

[0066] 2. The powder is preheated to remove internal moisture and increase its heat storage capacity. The preheating temperature is 320℃ and the preheating time is 15 minutes to form preheated powder.

[0067] 3. The preheated powder is fed into a suspension reduction calcination furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeder. The reduction reaction device is connected to the bottom gas feeder. Nitrogen and reducing gas are introduced through the gas feeder, with the volume percentage of N2 in the reducing gas being 55%. The amount of reducing gas used is 1.2 times the theoretical amount of CO / H2 required for complete reduction calcination. The calcination temperature is adjusted by the temperature control device, set to 1100℃, and the reaction time is 60 minutes to obtain the reduced product.

[0068] 4. The reduced product is subjected to cyclone gas-solid separation with a purification residence time of 6 minutes. The purified solid particles are then cooled to 95°C to obtain cooled material.

[0069] 5. The cooled material is subjected to dry weak magnetic separation. The magnetic field strength of the dry weak magnetic separation is 150kA / m to obtain iron and copper magnetic separation concentrate.

[0070] The iron and copper concentrates contained 82.43% TFe and 6.85% Cu by mass percentage, with recoveries of 88.94% TFe and 84.07% Cu, respectively.

[0071] Example 5

[0072] Similar to Example 1, except that the roasting temperature of the copper slag preheated powder during the reduction roasting process is 800℃ and the reaction time is 40min. The reduced product is purified, cooled, and separated by magnetic separation to obtain iron and copper concentrates containing 78.64% TFe and 4.96% Cu by mass percentage, with recovery rates of 92.23% TFe and 84.98% Cu, respectively.

[0073] Example 6

[0074] Similar to Example 1, the difference is that the amount of reducing gas used in the reduction roasting process is 1.2 times the theoretical amount of CO / H2 required for complete reduction roasting reaction, and the volume percentage of N2 in the reducing gas is 50%. After purification, cooling, and magnetic separation of the reduced product, iron and copper concentrates are obtained, containing 80.05% TFe and 5.21% Cu by mass percentage, with recovery rates of 91.88% TFe and 84.96% Cu, respectively.

[0075] Example 7

[0076] Similar to Example 3, except that the preheating temperature of the preheated powder was 300℃ and the preheating time was 15 min. After reduction roasting, purification cooling, and magnetic separation, iron and copper concentrates were obtained with a mass percentage content of 80.26% TFe and 6.01% Cu, and the recovery rates were 89.12% TFe and 84.08% Cu, respectively.

[0077] Example 8

[0078] Similar to Example 4, except that the magnetic field strength of the dry weak magnetic separation of the cooled material is 180 kA / m, and the iron and copper concentrates contain 84.27% TFe and 6.91% Cu by mass percentage, with recovery rates of 88.23% TFe and 83.86% Cu, respectively.

[0079] Comparative Example 1

[0080] A method for the co-process dry recovery of iron and copper from copper smelting slag, the process flow diagram of which is shown below. Figure 1 The specific operation method is as follows:

[0081] The main components of the copper smelting slag in this embodiment, by mass percentage, are Fe2O3 42.27%, SiO2 10.21%, ZnO 11.34%, CaO 10.47%, Al2O3 3.26%, and CuO 1.18%.

[0082] 1. The portion of copper smelting slag that is crushed and ground to a particle size of -0.074mm accounts for 90% of the total mass, and is then made into powder;

[0083] 2. Preheat the powder to remove internal moisture. The preheating temperature is 280℃ and the preheating time is 12 minutes to form preheated powder.

[0084] 3. The preheated powder is fed into a suspension reduction roasting furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeding device. The reduction reaction device is connected to the bottom gas feeding device. Nitrogen and reducing gas are introduced through the gas feeding device, with the volume percentage of N2 in the reducing gas being 50%. The amount of reducing gas used is 1.2 times the theoretical amount of CO / H2 required for complete reduction roasting. The roasting temperature is adjusted by the temperature control device, set to 550℃, and the reaction time is 25 minutes to obtain the reduced product.

[0085] 4. The reduced product is subjected to cyclone gas-solid separation with a purification residence time of 5 minutes. The purified solid particles are then cooled to 95°C to obtain cooled material.

[0086] 5. The cooled material is subjected to dry weak magnetic separation. The magnetic field strength of the dry weak magnetic separation is 120kA / m to obtain iron and copper magnetic separation concentrate.

[0087] The iron and copper concentrates contained 68.43% TFe and 4.17% Cu by mass percentage, with recoveries of 82.68% TFe and 79.34% Cu, respectively.

[0088] Comparative Example 2

[0089] A method for the co-process dry recovery of iron and copper from copper smelting slag, the process flow diagram of which is shown below. Figure 1 The specific operation method is as follows:

[0090] The main components of the copper smelting slag in this embodiment, by mass percentage, are Fe2O3 40.89%, SiO2 11.43%, ZnO 11.64%, CaO 9.13%, Al2O3 3.55%, and CuO 1.43%.

[0091] 1. The portion of copper smelting slag that is crushed and ground to a particle size of -0.074mm accounts for 90% of the total mass, and is then made into powder;

[0092] 2. Preheat the powder to remove internal moisture. The preheating temperature is 180℃ and the preheating time is 15 minutes to form preheated powder.

[0093] 3. The preheated powder is fed into a suspension reduction calcination furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeder. The reduction reaction device is connected to the bottom gas feeder. Nitrogen and reducing gas are introduced through the gas feeder, with the volume percentage of N2 in the reducing gas being 50%. The amount of reducing gas used is 1.2 times the theoretical CO / H2 amount required for complete reduction calcination. The calcination temperature is adjusted by the temperature control device, set to 800℃, and the reaction time is 30 minutes to obtain the reduced product.

[0094] 4. The reduced product is subjected to cyclone gas-solid separation with a purification residence time of 5 minutes. The purified solid particles are then cooled to 95°C to obtain cooled material.

[0095] 5. The cooled material is subjected to dry weak magnetic separation. The magnetic field strength of the dry weak magnetic separation is 200kA / m to obtain iron and copper magnetic separation concentrate.

[0096] The iron and copper concentrates contained 63.16% TFe and 3.09% Cu by mass percentage, with recoveries of 84.79% TFe and 81.26% Cu, respectively.

Claims

1. A method for the co-process dry recovery of iron and copper from copper smelting slag, characterized in that, The specific steps are as follows: Step 1: Crushing and grinding: The copper smelting slag is crushed and ground until the portion with a particle size of less than 0.074 mm accounts for ≥85% of the total mass, and then made into powder. Step 2: Preheating and dehydration: Preheat the powder at a temperature of 200-350℃ for 10-15 minutes to obtain preheated powder. Step 3: Reduction Calcination: The preheated powder is fed into a suspension reduction calcination furnace, which consists of a reduction reaction device, a temperature control device, and a gas feeding device. The reduction reaction device is connected to the gas feeding device at the bottom. Nitrogen and reducing gas are introduced through the gas feeding device. The reducing gas is CO and / or H2. The calcination temperature is adjusted by the temperature control device to reduce and calcine the preheated powder in a suspension state to obtain the reduced product. The reaction equations involved in the reduction roasting process are: 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) FeAl2O4(s)+CO / H2(g)=Fe(s)+Al2O3(s)+CO2 / H2O(g) (4) FeO·SiO2(s)+CO / H2(g)=Fe(s)+SiO2(s)+CO2 / H2O(g) (5) CuO(s)+CO / H2(g)=Cu+CO2 / H2O(g) (6); Step 4: Purification and Cooling: The reduced product is subjected to cyclone gas-solid separation to obtain purified solid particles, which are then cooled to obtain cooled material. Step 5: Perform dry weak magnetic separation on the cooled material to obtain iron and copper magnetic concentrate; The volume percentage of N2 mentioned in step 3 is 45%~65%; the amount of reducing gas used is 1.1~1.2 times the theoretical amount of CO and / or H2 required for complete reduction roasting reaction; The reaction temperature of the preheated powder in the suspension reduction calcination furnace in step 3 is 600~1100℃, and the reaction time is 30~60min; The magnetic field strength of the dry weak magnetic separation described in step 5 is 80-180 kA / m.

2. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The copper smelting slag mentioned in step 1 contains 30% to 50% iron and 0.5% to 3% copper.

3. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The reducing gas mentioned in step 3 is H2 and / or CO produced by coal gasification or natural gas cracking.

4. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The purification time for the reduced product mentioned in step 4 is 3-6 minutes.

5. The method for co-processing dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The discharge temperature of the cooled material mentioned in step 4 is ≤100℃.

6. The method for co-process dry recovery of iron and copper from copper smelting slag according to claim 1, characterized in that, The magnetic separation concentrate described in step 5 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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