Electric furnace slag waste heat recovery system, waste heat recovery method and RKEF process ferronickel production system

Abstract

The invention provides an electric furnace slag waste heat recovery system, a waste heat recovery method and an RKEF process ferronickel production system.The electric furnace slag waste heat recovery system comprises a hot slag bin used for collecting preliminarily cooled high-temperature slag; the heat exchanger is connected with the hot slag bin and is used for receiving the high-temperature slag in the hot slag bin and carrying out heat exchange to generate hot air; one end of the hot air conveying pipe is connected with a hot air outlet of the heat exchanger, and the other end of the hot air conveying pipe is connected with a secondary air inlet of a rotary kiln combustor; the waste heat utilization rate of the high-temperature melting electric furnace slag can be increased, and the demand quantity of pulverized coal or coal gas of the rotary kiln can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of smelting waste heat recovery, and in particular to an electric furnace slag waste heat recovery system, a waste heat recovery method and a RKEF process nickel-iron production system. Background Art

[0002] The RKEF (Rotary Klin Electric Furnace) process is a commonly used method in ferronickel ore smelting. It mainly uses a rotary kiln to dry and roast the laterite nickel ore for pre-reduction, and then uses an electric furnace for smelting and reduction to produce crude ferronickel. The RKEF ferronickel smelting process mainly includes the following steps:

[0003] 1. Drying: Use a rotary drying kiln to remove some of the free water in the ore, so that the moisture content of the ore is reduced to a level suitable for subsequent processing;

[0004] 2. Roasting-pre-reduction: In the rotary kiln, the ore is further degassed with remaining free water and crystal water, the ore is preheated, and part of the nickel and iron are selectively reduced. This process is usually carried out at a temperature of 750°C to 850°C.

[0005] 3. Electric furnace smelting: add the roasted ore into the electric furnace, reduce the metallic nickel and part of the iron at high temperature, separate the slag and nickel iron at the same time, and produce crude nickel iron;

[0006] 4. Refining: Through the refining process, the crude nickel iron is further removed from impurities such as sulfur and phosphorus to obtain nickel iron products that meet market demand.

[0007] The flue gas generated by the rotary kiln enters the drying kiln to dry the materials. Coal powder or coal gas is burned at the kiln head to provide heat for the rotary kiln; burning coal powder or coal gas at the kiln head requires a large amount of combustion air, and normal temperature air is generally used as the combustion air, which makes the demand for coal powder or coal gas relatively large;

[0008] During the smelting process of the electric furnace, the temperature of the molten slag out of the furnace is about 1450℃, but the slag is usually discharged intermittently, so it is very difficult to recycle its heat energy and the utilization rate is not high. 85% to 90% of the molten slag of the electric furnace is used as raw materials such as cement or used to make slag bricks and lightweight concrete blocks after water quenching; these water quenching methods have high water consumption for slag washing, the waste heat is not effectively recycled, and it also pollutes the environment.

[0009] Therefore, there is an urgent need for an electric furnace slag waste heat recovery system, a waste heat recovery method and a RKEF process nickel-iron production system, which can not only improve the utilization rate of waste heat from high-temperature melting, but also reduce the demand for coal powder or coal gas in the rotary kiln. Summary of the invention

[0010] The purpose of the present invention is to provide an electric furnace slag waste heat recovery system, a waste heat recovery method and a RKEF process nickel-iron production system, aiming to solve the technical problems of low utilization rate of traditional electric furnace slag waste heat and high demand for coal powder or coal gas of rotary kiln.

[0011] To achieve the above objectives, in a first aspect, the present invention provides an electric furnace slag waste heat recovery system, comprising:

[0012] Hot slag bin, used to collect high-temperature slag after preliminary cooling;

[0013] A heat exchanger connected to the hot slag bin, used to receive the high-temperature slag in the hot slag bin and perform heat exchange to generate hot air;

[0014] A hot air delivery pipe has one end connected to the hot air outlet of the heat exchanger and the other end connected to the secondary air inlet of the rotary kiln burner.

[0015] As a further improvement of the above scheme, the electric slag waste heat recovery system also includes a cooling device for preliminarily cooling the molten electric slag produced by the electric furnace to a first temperature range for transfer.

[0016] As a further improvement of the above solution, a first control valve is further provided between the hot slag bin and the heat exchanger for controlling the connection between the hot slag bin and the heat exchanger and the speed at which the high-temperature slag enters the heat exchanger.

[0017] As a further improvement of the above scheme, the electric furnace slag waste heat recovery system also includes a monitoring and control module, which is used to monitor the temperature of the high-temperature slag and air in the heat exchanger in real time, as well as the output temperature of the hot air outlet, and automatically control the high-temperature slag entry speed and the opening and closing of the hot air outlet according to the set parameters.

[0018] As a further improvement of the above solution, the monitoring and control module includes a temperature monitoring unit and a second control valve, and the second control valve is used to control the flow of the hot air delivery pipe;

[0019] The temperature monitoring unit is used to detect the real-time temperature of the hot air. The temperature monitoring unit is communicatively connected with the second control valve to control the opening of the second control valve according to the monitored temperature value.

[0020] In a second aspect, the present invention further provides a method for recovering waste heat from electric furnace slag in a RKEF process, the steps of which include:

[0021] S1, transferring the high-temperature slag after preliminary cooling to the hot slag bin for buffering;

[0022] S2, allowing the high-temperature slag in the hot slag bin to enter the heat exchanger at a uniform speed, and at the same time opening the air inlet of the heat exchanger to allow cold air to enter the heat exchanger and perform heat exchange with the high-temperature slag in the heat exchanger;

[0023] S3. When the cold air is heated to reach the second temperature range, the hot air is continuously transported to the burner of the rotary kiln as combustion-supporting air.

[0024] As a further improvement of the above scheme, before step S1, it also includes step S0: preliminarily cooling the molten electric slag to a first temperature range;

[0025] Preferably, the first temperature range is 700°C to 900°C, ensuring that the electric furnace slag is in the temperature range of 700°C to 900°C before entering the hot slag bin.

[0026] As a further improvement of the above scheme, in step S0, the molten electric furnace slag is forcedly cooled to between 700°C and 900°C by air crushing or a slag casting machine.

[0027] As a further improvement of the above scheme, in step S3, the high-temperature slag is cooled to 100±10° C. in the heat exchanger and then discharged.

[0028] As a further improvement of the above scheme, in step S3, the second temperature range is 500°C~600°C. When it is detected that the hot air temperature in the heat exchanger is between 500°C~600°C, the corresponding channel is opened to transport the hot air to the rotary kiln as combustion-supporting air.

[0029] In a third aspect, the present invention also provides a RKEF process nickel-iron production system, comprising a rotary drying kiln for drying, a rotary kiln for roasting pre-reduced ore and an electric furnace for smelting and producing crude nickel-iron, and also includes an electric furnace slag waste heat recovery system as provided in the first aspect.

[0030] Since the present invention adopts the above technical solution, the beneficial effects of this application are:

[0031] The present invention provides an electric furnace slag waste heat recovery system, comprising: a hot slag bin for collecting high-temperature slag that has been preliminarily cooled; a heat exchanger connected to the hot slag bin, for receiving the high-temperature slag in the hot slag bin and performing heat exchange to generate hot air; a hot air delivery pipe, one end of which is connected to the hot air outlet of the heat exchanger, and the other end is connected to the air inlet of the secondary air of the rotary kiln burner; with such an arrangement, the electric furnace slag intermittently discharged from the electric furnace is buffered and concentrated through the hot slag bin, and then the solid high-temperature slag that has been preliminarily cooled continuously enters the heat exchanger at an appropriate speed, and continuous hot air is generated in the heat exchanger, and finally the hot air is continuously transmitted to the rotary kiln burner through the hot air delivery pipe as a combustion aid. Wind; during the whole process, since the hot slag bin can buffer and concentrate the solid slag, combined with controlling the speed of the high-temperature slag entering the heat exchanger, the combustion-supporting hot air can be guaranteed to be continuous and stable, thereby improving the utilization rate of waste heat and making the rotary kiln combustion stable; since the rotary kiln has increased the heat input, from the perspective of thermal balance, it can save the demand for coal powder or coal gas and reduce energy consumption; at the same time, the waste heat recovery system provided by the present invention can directly generate hot air for combustion support. Compared with the traditional method of utilizing waste heat from electric furnace slag (the traditional waste heat recovery is to generate steam from the recovered waste heat, and then use the steam to generate electricity, which has low waste heat utilization efficiency and may also cause the value of the recovered waste heat to be lower than the investment value of the recovery system), it can improve the utilization rate of waste heat from electric furnace slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0033] Figure 1 This is a schematic diagram of the principle of an electric furnace slag waste heat recovery system disclosed in the present invention;

[0034] Figure 2 The present invention discloses a schematic diagram of the principle of a nickel-iron production system using a RKEF process.

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0039] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] Example 1

[0041] See also Figure 1 The present invention provides an electric furnace slag waste heat recovery system, comprising:

[0042] A cooling device is used to preliminarily cool the molten electric furnace slag produced by the electric furnace to a first temperature range for transfer; preferably, the first temperature range is between 700°C and 900°C. Within this temperature range, the molten electric furnace slag becomes solid high-temperature slag, which is convenient for transferring it to the hot slag bin;

[0043] Hot slag bin, used to collect high-temperature slag after preliminary cooling;

[0044] A heat exchanger connected to the hot slag bin, used to receive the high-temperature slag in the hot slag bin and perform heat exchange to generate hot air;

[0045] A hot air delivery pipe, one end of which is connected to the hot air outlet of the heat exchanger, and the other end of which is connected to the secondary air inlet of the rotary kiln burner;

[0046] With such an arrangement, the electric slag intermittently discharged from the electric furnace is cached and concentrated through the hot slag bin, and then the solid high-temperature slag that has been initially cooled continuously enters the heat exchanger at an appropriate speed, and continuous hot air is generated in the heat exchanger, and finally the hot air is continuously transmitted to the rotary kiln burner as combustion-supporting air through the hot air conveying pipe; in the whole process, since the hot slag bin can cache and concentrate the solid slag, combined with controlling the speed of the high-temperature slag entering the heat exchanger, the combustion-supporting hot air can be guaranteed to be continuous and stable, thereby improving the utilization rate of waste heat and making the combustion of the rotary kiln stable; since the rotary kiln has increased heat input, from the perspective of thermal balance, the demand for coal powder or coal gas can be saved and energy consumption can be reduced; at the same time, the waste heat recovery system provided by the present invention can directly generate hot air for combustion support, which can improve the utilization rate of waste heat of electric slag compared with the traditional method of utilizing waste heat of electric slag (the traditional waste heat recovery is to generate steam from the recovered waste heat, and then use the steam to generate electricity, which has low waste heat utilization efficiency and may also cause the value of recovered waste heat to be lower than the investment value of the recovery system).

[0047] As a preferred embodiment, a first control valve is further provided between the hot slag bin and the heat exchanger, for controlling the on-off connection between the hot slag bin and the heat exchanger and the speed at which the high-temperature slag enters the heat exchanger; by controlling the first control valve, the speed at which the high-temperature slag enters the heat exchanger can be accurately adjusted to optimize the heat exchange efficiency and the stability of the hot air output.

[0048] As a preferred embodiment, the electric furnace slag waste heat recovery system also includes a monitoring and control module, which is used to monitor the temperature of the high-temperature slag and air in the heat exchanger in real time, as well as the output temperature of the hot air outlet, and automatically control the high-temperature slag entry speed and the opening and closing of the hot air outlet according to the set parameters;

[0049] Specifically, the monitoring and control module includes a temperature monitoring unit and a second control valve, and the second control valve is used to control the flow of the hot air delivery pipe;

[0050] The temperature monitoring unit is used to detect the real-time temperature of the hot air. The temperature monitoring unit is in communication connection with the second control valve to control the opening of the second control valve according to the monitored temperature value.

[0051] Specifically, when the output temperature of the hot air outlet reaches the second temperature range, the second control valve opens to output the hot air to the rotary kiln as combustion-supporting air. Preferably, the second temperature range is 500°C~600°C; during the control process, the entry speed of the high-temperature slag can be adjusted according to the temperature value of the hot air monitored, so as to be able to output continuous and stable hot air as the combustion-supporting air of the rotary kiln; for example, if within the preset time period, the temperature monitoring unit monitors that the temperature of the hot air is between 500°C~550°C, the entry speed of the high-temperature slag can be adjusted faster; if within the preset time period, the temperature monitoring unit monitors that the temperature of the hot air is between 550°C~600°C, the entry speed of the high-temperature slag can be adjusted slower to ensure that the hot air within the second temperature range can be continuously output.

[0052] Example 2

[0053] The present invention also provides a RKEF process electric furnace slag waste heat recovery method, the steps of which include:

[0054] S0, preliminarily cooling the molten electric slag to a first temperature range;

[0055] Preferably, the first temperature range is 700°C to 900°C, ensuring that the electric furnace slag is in the temperature range of 700°C to 900°C before entering the hot slag bin; the molten electric furnace slag is forcedly cooled to between 700°C and 900°C by wind crushing or slag casting machine;

[0056] S1, transferring the high-temperature slag after preliminary cooling to the hot slag bin for buffering;

[0057] S2, allowing the high-temperature slag in the hot slag bin to enter the heat exchanger at a uniform speed, and at the same time opening the air inlet of the heat exchanger to allow cold air to enter the heat exchanger and perform heat exchange with the high-temperature slag in the heat exchanger;

[0058] S3. When the cold air is heated to reach the second temperature range, the hot air is continuously transported to the burner of the rotary kiln as combustion-supporting air; specifically, the second temperature range is 500°C~600°C. When it is detected that the temperature of the hot air in the heat exchanger is between 500°C~600°C, the corresponding channel is opened to transport the hot air to the rotary kiln as combustion-supporting air; a first control valve is provided between the hot slag bin and the heat exchanger to control the on-off between the hot slag bin and the heat exchanger and the speed at which the high-temperature slag enters the heat exchanger. The speed at which the high-temperature slag enters the heat exchanger can be adjusted by regulating the opening of the first control valve, so that the hot air can be stably heated to the second temperature range, thereby ensuring that the hot air can be continuously transported to the secondary air inlet of the rotary kiln burner as combustion-supporting air;

[0059] The high temperature slag is cooled to 100±10° C. in the heat exchanger and then discharged.

[0060] Specifically, in order to further illustrate a RKEF process electric furnace slag waste heat recovery method provided by the present invention, taking the RKEF process with a daily output of 1,824 tons of dry slag as an example, the molten slag is forced to cool to about 700-900°C by wind crushing or slag casting machine, and enters the hot slag bin as solid high-temperature slag for buffering, and then enters the heat exchanger at about 76 tons of slag per hour. Cold air enters the heat exchanger to cool the high-temperature slag, and the high-temperature slag is discharged after being cooled to about 100°C, and sent back to the slag plant for sale. The cold air entering the heat exchanger is heated by the high-temperature slag and output after reaching 500-600°C. The output hot air is used as the combustion-supporting air of the rotary kiln burner. For ease of calculation, the speed at which the high-temperature slag enters the heat exchanger is 76 tons / hour, the high-temperature slag temperature is 750°C, the cold slag temperature is 105°C, and the air volume is 65,000 Nm 3 / h calculation, the temperature of the heated hot air is 525℃, and its heat balance calculation is shown in Table 1.

[0061]

[0062] For a single rotary kiln, the combustion air is at room temperature, and the gas consumption per hour is: 42834 Nm 3 / h, and its heat balance table is shown in Table 2.

[0063]

[0064] For a single rotary kiln, the combustion air is hot air, the temperature is 525℃, and the combustion air volume is 41844Nm 3 / h, gas consumption per hour: 36163 Nm 3 / h, after calculation, its heat balance table is shown in Table 3.

[0065]

[0066] By comparing Table 2 and Table 3, the hot air efficiency can be obtained as shown in Table 4.

[0067]

[0068] It can be seen from the hot air economic and technical indicator table in Table 4 that the RKEF process electric furnace slag waste heat recovery method provided by the present invention can effectively save gas volume and achieve the purpose of reducing energy consumption; and its hot air efficiency is also effectively improved; compared with the traditional water quenching method for treating high-temperature molten electric furnace slag, the water consumption is very low, the heat can be effectively recycled and utilized, and it will not cause pollution to the environment.

[0069] Example 3

[0070] The present invention also provides a RKEF process nickel-iron production system, comprising a rotary drying kiln for drying, a rotary kiln for roasting pre-reduced ore, and an electric furnace for smelting and producing crude nickel-iron, and also comprising an electric furnace slag waste heat recovery system as provided in Example 1;

[0071] To further illustrate the inventive concept of the present invention and the beneficial effects achieved by the inventive concept, the following describes the forced cooling of molten electric furnace slag by using a slag casting machine as a cooling device.

[0072] First, a slag casting machine is used to cool the high-temperature slag into small pieces of high-temperature slag. The temperature of the small pieces of high-temperature slag is controlled between 700 and 900°C (750°C is used as an example for calculation and explanation), and then it is transferred to the heat-resistant slag bin through a high-temperature resistant scale plate conveyor. The high-temperature slag is discharged at 1,800 tons / day, 6 times a day, and each discharge is 2 hours. The high-temperature slag flow rate is 150 tons / hour during slag discharge. The hot slag bin must buffer the slag for 2 hours. The high-temperature slag bulk density is 2.0 tons / cubic meter, and the volume of the hot slag bin is greater than 75 cubic meters. The high-temperature slag in the hot slag bin enters the heat exchanger (vertical cooler) at a rate of 75 tons of slag per hour. After cooling, the high-temperature slag is cooled to 90~120°C (105°C is used as an example for calculation and explanation) and discharged. The air is pressurized by a fan at 65,000 Nm 3 / h is sent to the heat exchanger (vertical cooler), and the cold air is heated to 500~600℃ (518℃ is used as an example for calculation) by the high-temperature slag, and is used as hot air to provide combustion-supporting air for the rotary kiln burner. The heat balance calculation is shown in Table 5. Since the high-temperature slag is buffered by the heat-resistant slag bin, the combustion-supporting air can be guaranteed to be continuous and stable, making the combustion of the rotary kiln stable.

[0073]

[0074] For a single rotary kiln, the combustion air is at room temperature, and the gas consumption per hour is: 42834 Nm 3 / h, and its heat balance table is shown in Table 6.

[0075]

[0076] For a single rotary kiln, the combustion air is hot air, the temperature is 518℃, and the combustion air volume is 41932 Nm 3 / h, gas consumption per hour: 36163 Nm 3 / h, after calculation, its heat balance table is shown in Table 7.

[0077]

[0078] The hot air efficiency is shown in Table 8:

[0079]

[0080] It can be seen from the hot air economic and technical indicator table in Table 8 that the present invention provides a RKEF process nickel-iron production system, which uses a slag casting machine as a cooling device to force cool the molten electric furnace slag. The high-temperature slag enters the heat exchanger at a rate of 75 tons of slag per hour, which can effectively save gas (in this embodiment, the amount of gas saved is 6595.00 Nm 3 / h), thus achieving the goal of reducing energy consumption; and its hot air efficiency is also effectively improved; compared with the traditional water quenching method for treating high-temperature molten electric furnace slag, the water consumption is very low, the heat can be effectively recycled, and it will not cause pollution to the environment.

[0081] Next, the forced cooling of molten electric furnace slag by using wind crusher as cooling device is explained.

[0082] First, high-pressure wind and water mist are used to break up the high-temperature slag. The temperature of small pieces of high-temperature slag is controlled between 700 and 900°C (750°C is used as an example for calculation and explanation), and then it is transferred to the heat-resistant slag bin through a high-temperature resistant scale conveyor. The high-temperature slag is discharged at 1,344 tons / day, 6 times a day, and each discharge is 2 hours. The high-temperature slag flow rate is 112 tons / hour during slag discharge. The hot slag bin needs to buffer the slag for 2 hours. The high-temperature slag bulk density is 2.0 tons / cubic meter, and the volume of the hot slag bin is greater than 56 cubic meters. The high-temperature slag in the hot slag bin enters the heat exchanger (vertical cooler) at a rate of 56 tons of slag per hour. After cooling, the high-temperature slag is cooled to 90~120°C (105°C is used as an example for calculation and explanation) and discharged. The air is pressurized by the fan at 49,000 Nm 3 / h is sent to the heat exchanger (vertical cooler), and the cold air is heated to 500~600℃ (513℃ is used as an example for calculation) by the high-temperature slag, and is used as hot air to provide combustion-supporting air for the rotary kiln burner. The heat balance calculation is shown in Table 9. Since the high-temperature slag is buffered by the heat-resistant slag bin, the combustion-supporting air can be guaranteed to be continuous and stable, making the combustion of the rotary kiln stable.

[0083]

[0084] For a single rotary kiln, the combustion air is at room temperature, and the gas consumption per hour is: 30466 Nm 3 / h, as shown in the heat balance table 10.

[0085]

[0086] For a single rotary kiln, the combustion air is hot air, the temperature is 513℃, and the combustion air volume is 29828Nm 3 / h, gas consumption per hour: 25778Nm 3 / h, after calculation, its heat balance is shown in Table 11.

[0087]

[0088] The hot air efficiency is shown in Table 12.

[0089]

[0090] It can be seen from the hot air economic and technical indicator table in Table 12 that the present invention provides a RKEF process nickel-iron production system, which uses wind crushing as a cooling device to force cool the molten electric furnace slag. The high-temperature slag enters the heat exchanger at 56 tons of slag per hour, which can effectively save the amount of gas (in this embodiment, the amount of gas saved is 4688.30 Nm 3 / h), achieving the purpose of reducing energy consumption; and its hot air efficiency is also effectively improved; compared with the traditional water quenching method for treating high-temperature molten electric furnace slag, the water consumption is very low, the heat can be effectively recycled, and it will not cause pollution to the environment; comparing Table 8 and Table 12, both cooling devices can effectively reduce the amount of gas, and the faster the high-temperature slag enters the heat exchanger, the higher the amount of gas saved.

[0091] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An electric furnace slag waste heat recovery system, characterized in that: include: Hot slag bin, used to collect high-temperature slag after preliminary cooling; A heat exchanger connected to the hot slag bin, used to receive the high-temperature slag in the hot slag bin and perform heat exchange to generate hot air; A hot air delivery pipe has one end connected to the hot air outlet of the heat exchanger and the other end connected to the secondary air inlet of the rotary kiln burner.

2. The electric furnace slag waste heat recovery system according to claim 1, characterized in that: The electric slag waste heat recovery system also includes a cooling device for preliminarily cooling the molten electric slag produced by the electric furnace to a first temperature range for transfer.

3. An electric furnace slag waste heat recovery system according to claim 1 or 2, characterized in that: A first control valve is also provided between the hot slag bin and the heat exchanger, for controlling the connection between the hot slag bin and the heat exchanger and the speed at which the high-temperature slag enters the heat exchanger.

4. An electric furnace slag waste heat recovery system according to claim 1 or 2, characterized in that: The electric furnace slag waste heat recovery system also includes a monitoring and control module for real-time monitoring the temperature of the high-temperature slag and air in the heat exchanger, as well as the output temperature of the hot air outlet, and automatically controlling the high-temperature slag entry speed and the opening and closing of the hot air outlet according to set parameters.

5. The electric furnace slag waste heat recovery system according to claim 4, characterized in that: The monitoring and control module includes a temperature monitoring unit and a second control valve, wherein the second control valve is used to control the flow rate of the hot air delivery pipe; The temperature monitoring unit is used to detect the real-time temperature of the hot air. The temperature monitoring unit is communicatively connected with the second control valve to control the opening of the second control valve according to the monitored temperature value.

6. A RKEF process electric furnace slag waste heat recovery method, characterized in that: The steps include: S1, transferring the high-temperature slag after preliminary cooling to the hot slag bin for buffering; S2, allowing the high-temperature slag in the hot slag bin to enter the heat exchanger at a uniform speed, and at the same time opening the air inlet of the heat exchanger to allow cold air to enter the heat exchanger and perform heat exchange with the high-temperature slag in the heat exchanger; S3. When the cold air is heated to reach the second temperature range, the hot air is continuously transported to the burner of the rotary kiln as combustion-supporting air.

7. A RKEF process electric furnace slag waste heat recovery method according to claim 6, characterized in that: Before step S1, the method further includes step S0: preliminarily cooling the molten electric slag to a first temperature range; The first temperature range is 700° C. to 900° C., ensuring that the electric furnace slag is in the temperature range of 700° C. to 900° C. before entering the hot slag bin.

8. A RKEF process electric furnace slag waste heat recovery method according to claim 7, characterized in that: In step S0, the molten electric furnace slag is forcedly cooled to between 700°C and 900°C by air crushing or a slag casting machine.

9. A RKEF process electric furnace slag waste heat recovery method according to any one of claims 6-8, characterized in that: In step S3, the second temperature range is 500°C-600°C. When it is detected that the hot air temperature in the heat exchanger is between 500°C-600°C, the corresponding channel is opened to transport the hot air to the rotary kiln as combustion-supporting air.

10. A RKEF process nickel-iron production system, characterized in that: It comprises a rotary drying kiln for drying, a rotary kiln for roasting pre-reduced ore and an electric furnace for smelting and producing crude ferronickel, and also comprises an electric furnace slag waste heat recovery system as described in any one of claims 1-5.

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