A device for preheating scrap steel using waste heat from steel slag

Abstract

The present invention provides a device for preheating scrap steel using the waste heat of slag, comprising: a ladle, wherein the ladle contains slag; a slag pan, wherein the slag pan is inclined, wherein the ladle is located above one end of the slag pan, and wherein the ladle dumps the slag into the slag pan; a screener, wherein the screener inlet is located below the other end of the slag pan, and the slag in the slag pan slides down into the screener by itself under the action of gravity; and a spiral heat exchanger, wherein the spiral heat exchanger comprises a housing, a motor reducer, a rotating shaft, a heat exchange tube, spiral blades, a front slag baffle plate, a rear slag baffle plate, a spiral heat exchanger air inlet, a spiral heat exchanger air outlet, a spiral heat exchanger feed port, and a spiral heat exchanger slag outlet. In the present invention, the slag feed port and the slag outlet of the spiral heat exchanger should be arranged between the slag baffle plate and the rear slag baffle plate to ensure that the slag is only transported between the two baffles; a large amount of slag dust can be effectively prevented from entering the hot air circulation system, thereby reducing costs and being more conducive to environmental protection.

Description

Technical Field

[0001] The invention belongs to the field of steelmaking converter slag waste heat recovery, and specifically relates to a device for preheating scrap steel using slag waste heat. Background Art

[0002] Steel slag is waste slag produced in the metallurgical industry, and its production rate is 8% to 15% of crude steel production. With the development of the steel industry, the waste heat utilization of steel slag has received more and more attention. The temperature of molten steel slag is between 1400 and 1750°C, and the specific heat capacity of slag is about 1KJ / (kg.°C). Through calculation, it can be seen that when steel slag is reduced from 1400°C to 500°C, 9×105KJ of sensible heat can be recovered per ton of molten slag, which is equivalent to the heat generated by the complete combustion of 30kg of standard coal.

[0003] At present, the most common way to recover waste heat from steel slag is to use flue gas waste heat boilers, use air as a heat exchange medium, and recover waste heat to produce steam, hot water, etc. The disadvantage of this recovery method is that it converts high-temperature waste heat into low-temperature waste heat, which limits its application in medium and high temperature environments. As for the preheating process of scrap steel, most of them are now directly preheated by electric furnaces or gas heating furnaces. If the heat from steel slag waste heat is used to replace this part of energy, the energy consumption indicators of steel enterprises can be greatly reduced, which plays an important role in reducing carbon emissions.

[0004] The dust content in steel slag is very high. If the circulating air (i.e. gas) is mixed with steel slag, the dust content of the circulating air will inevitably increase. The circulating air temperature at this time is about 650℃, which is high-temperature smoke. Usually, dust removal equipment cannot handle it, and the efficiency of cyclone dust collector is low. If cyclone dust removal is added, the disadvantages are: increase the investment cost and floor space of the entire production line, increase heat loss; at the same time, it also increases the processing capacity of high-temperature dust removal ash and increases operating costs; a large amount of dust may adhere to the surface of scrap steel and enter the converter together, increasing dust emissions.

[0005] Therefore, designing a system that can utilize the waste heat of slag and fully utilize the waste heat to preheat scrap steel without increasing dust pollution is a practical problem that needs to be solved in steel production. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and provide a device for preheating scrap steel using waste heat from slag, aiming to solve the problems of recovering high-temperature waste heat from slag, preheating scrap steel in converters and reducing energy consumption indicators for steelmaking.

[0007] The technical solution adopted by the present invention is:

[0008] A device for preheating scrap steel using waste heat from steel slag, comprising:

[0009] a ladle containing steel slag;

[0010] A slag pan, wherein the slag pan is inclined, the ladle is located above one end of the slag pan, and the ladle pours the slag into the slag pan;

[0011] The screener has a feed port located below the other end of the slag pan, and the slag in the slag pan slides down into the screener under the action of gravity;

[0012] The spiral heat exchanger comprises a shell, a motor reducer, a rotating shaft, a heat exchange tube, a spiral blade, a front slag baffle, a rear slag baffle, an air inlet of the spiral heat exchanger, an air outlet of the spiral heat exchanger, a feed port of the spiral heat exchanger and a slag outlet of the spiral heat exchanger. The motor reducer drives the rotating shaft and the spiral blade to rotate. The front slag baffle and the rear slag baffle are respectively inserted into the rotating shaft on both sides of the spiral blade; an air inlet bin is formed between one side of the rear slag baffle and the shell, and an air outlet bin is formed between one side of the front slag baffle and the shell; the feed port of the spiral heat exchanger is connected to the lower portion of the sifter. The material inlet is butted, and the slag outlet of the spiral heat exchanger is butted with the slag bag; the steel slag flows to the slag outlet of the spiral heat exchanger driven by the spiral blades, the air inlet of the spiral heat exchanger is located on the upper side of the shell of the air inlet bin, and is connected to the high-pressure fan by means of a pipeline, and the air outlet of the spiral heat exchanger is located on the lower side of the shell of the air outlet bin, the heat exchange pipe is parallelly penetrated on the spiral blades, and the two ends of the heat exchange pipe are respectively passed through the front slag baffle plate and the rear slag baffle plate to be connected with the air outlet bin and the air inlet bin; the gas in the spiral heat exchanger is opposite to the flow direction of the steel slag, so that the steel slag and the gas exchange heat;

[0013] A scrap steel bin, wherein the scrap steel bin contains scrap steel, and an air inlet at the bottom of the scrap steel bin is connected to an air outlet of a spiral heat exchanger via a pipeline; the gas in the scrap steel bin moves from bottom to top, so that heat is exchanged between the scrap steel and the gas;

[0014] A dust collector, wherein the air inlet of the dust collector is connected to the air outlet at the upper part of the scrap steel bin by means of a pipeline; and the air outlet of the dust collector is connected to the air inlet of the cooler by means of a pipeline;

[0015] The air outlet of the cooler is connected to the high-pressure blower via a pipeline.

[0016] Furthermore, the heat exchange tube includes a tube body, external heat dissipation ribs and internal heat dissipation ribs; the external heat dissipation ribs are evenly distributed on the outer periphery of the tube body, and the internal heat dissipation ribs are evenly distributed inside the tube body in a radial pattern.

[0017] Furthermore, a gap is left between the front slag baffle plate, the rear slag baffle plate and the inner wall of the spiral heat exchanger shell.

[0018] Furthermore, a slag discharge valve is provided at the feed inlet of the spiral heat exchanger, and an ash discharge valve is provided at the discharge port of the dust collector.

[0019] Furthermore, a scrap steel bin inlet valve is provided on the pipeline connecting the scrap steel bin and the spiral heat exchanger; and a scrap steel bin outlet valve is provided on the pipeline connecting the scrap steel bin and the dust collector.

[0020] Furthermore, the number of the scrap steel bins is one or more.

[0021] Furthermore, a roller press is provided on the slag tray, and the roller press crushes large pieces of slag.

[0022] The beneficial effects obtained by the present invention are as follows: the present invention can effectively recover the waste heat contained in the converter slag, and use the heat to preheat steelmaking raw materials such as scrap steel that need to be preheated, without consuming a large amount of additional energy. The temperature of scrap steel entering the furnace is increased, thereby increasing the scrap steel ratio, thereby saving energy consumption in steelmaking production and reducing steelmaking energy consumption indicators.

[0023] The slag feed port and the slag discharge port of the spiral heat exchanger in the present invention should be arranged between the slag baffle plate and the rear slag baffle plate to ensure that the slag is only transported between the two baffles; a large amount of slag dust can be effectively prevented from entering the hot air circulation system, which reduces costs and is more conducive to environmental protection.

[0024] The temperature of the hot air increases after heat exchange. The hot air after the spiral heat exchanger enters the scrap steel bin through the scrap steel bin inlet valve. The hot air enters the scrap steel bin from the bottom through the gap of the scrap steel and exits from the top of the scrap steel bin. The wind speed in the bin is low, which can fully exchange heat with the scrap steel, and then preheat the scrap steel to the set temperature. The dust content in the scrap steel is large, so the hot air needs to be dusted. The hot air after heat exchange enters the dust collector for purification, and the dust is unloaded from the ash unloading valve at the bottom of the dust collector. There is an openable lid on the top of the scrap steel bin. After the temperature of the scrap steel in the bin reaches the equipment temperature, the inlet and outlet valves are closed, the lid is opened, and the scrap steel enters the next process after leaving the bin. There are generally two or more scrap steel bins, and the loading, working, and discharging states of the scrap steel bin are reciprocated. The temperature of the hot air leaving the scrap steel bin drops after heat exchange, and it is pressurized by the high-pressure fan through the pipeline and heated again, and then heat-exchanged with the scrap steel. When there is excess waste heat from slag, the temperature of the hot air out of the scrap steel bin is high. In order to protect the high-pressure blower, a cooler is installed here to reduce the air temperature with cooling water. At the same time, a part of high-temperature hot water or low-pressure steam can also be obtained, which can also recover the waste heat of slag. This reciprocating cycle can achieve the purpose of steel rolling waste heat recovery and scrap steel preheating. The locations of each device in the system that contact high-temperature slag or hot air must be lined with refractory and wear-resistant materials of different thicknesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the spiral heat exchanger of the present invention;

[0027] Figure 3This is a cross-sectional view of the spiral heat exchanger of the present invention;

[0028] Figure 4 This is a cross-sectional view of the heat exchange tube of the present invention;

[0029] Among them, 1 represents ladle, 2 represents roller press, 3 represents slag plate, 4 represents screener, 5 represents slag discharge valve, 6 represents spiral heat exchanger, 7 represents air duct, 8 represents high-pressure fan, 9 represents dust collector, 10 represents ash discharge valve, 11 represents scrap steel bin inlet valve, 12 represents scrap steel bin, 13 represents scrap steel bin outlet valve, 14 represents cooler, 6-1 represents casing, 6-2 represents motor reducer, 6-3 represents shaft, 6-4 represents spiral heat exchanger feed port, 6-5 represents spiral heat exchanger air inlet, 6-6 represents spiral heat exchanger air outlet, 6-7 represents spiral heat exchanger slag outlet, 6-8 represents front slag baffle, 6-9 represents rear slag baffle, 6-10 represents spiral blade, 6-11 represents heat exchange tube, 6-11-1 represents tube body, 6-11-2 represents external heat dissipation rib, 6-11-3 represents internal heat dissipation rib. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0031] like Figure 1-4As shown, a device for preheating scrap steel using waste heat of slag comprises: a ladle 1, wherein the ladle 1 contains slag; a slag pan 3, wherein the slag pan 3 is inclined, wherein the ladle 1 is located above one end of the slag pan 3, and wherein the ladle 1 pours the slag into the slag pan 3; a screener 4, wherein the feed port of the screener 4 is located below the other end of the slag pan 3, and the slag in the slag pan 3 slides down into the screener 4 by itself under the action of gravity; a spiral heat exchanger 6, wherein the spiral heat exchanger 6 comprises a housing 6-1, a motor reducer 6-2, a rotating shaft 6-3, a heat exchange tube 6-11, a spiral The blade 6-10, the front slag baffle plate 6-8, the rear slag baffle plate 6-9, the spiral heat exchanger air inlet 6-5 and the spiral heat exchanger air outlet 6-6, the motor reducer 6-2 drives the shaft 6-3 and the spiral blade 6-10 to rotate, the front slag baffle plate 6-8 and the rear slag baffle plate 6-9 are respectively inserted on the shaft 6-3 on both sides of the spiral blade 6-10; one side of the rear slag baffle plate 6-9 and the shell 6-1 form an air inlet bin, and one side of the front slag baffle plate 6-8 and the shell 6-3 form an air outlet bin; the spiral heat exchanger feed port 6-4 is connected to the discharge port of the screener 4. The slag outlet 6-7 of the spiral heat exchanger is connected to the slag bag; the steel slag flows to the slag outlet 6-7 of the spiral heat exchanger driven by the spiral blade 6-10, the air inlet 6-5 of the spiral heat exchanger is located on the upper side of the shell 6-1 of the air inlet bin and is connected to the high-pressure fan 8 by means of a pipeline, the air outlet 6-6 of the spiral heat exchanger is located on the lower side of the shell 6-1 of the air outlet bin, the heat exchange pipe 6-11 is parallelly penetrated on the spiral blade 6-10, and the two ends of the heat exchange pipe 6-11 pass through the front slag baffle plate 6-8 and the rear slag baffle plate 6-9 respectively and are connected to the air outlet bin and the air inlet bin; the spiral The gas in the spiral heat exchanger 6 flows in opposite directions to the slag, so that heat is exchanged between the slag and the gas; the scrap steel bin 12, wherein the scrap steel 12 contains scrap steel, and the bottom air inlet of the scrap steel bin 12 is connected to the air outlet 6-6 of the spiral heat exchanger by means of a pipeline; the gas in the scrap steel bin 12 moves from bottom to top, so that heat is exchanged between the scrap steel and the gas; the dust collector 9, wherein the air inlet of the dust collector 9 is connected to the upper air outlet of the scrap steel bin 12 by means of a pipeline; the air outlet of the dust collector 9 is connected to the air inlet of the cooler 14 by means of a pipeline; the air outlet of the cooler 14 is connected to the high-pressure fan 8 by means of a pipeline.

[0032] The heat exchange tube 6-11 includes a tube body 6-11-1, an outer heat dissipation rib 6-11-2 and an inner heat dissipation rib 6-11-3; the outer heat dissipation rib 6-11-2 is evenly distributed on the outer periphery of the tube body 6-11-1, and the inner heat dissipation rib 6-11-3 is evenly distributed inside the tube body 6-11-1 in a radial shape. A gap is left between the front slag baffle plate 6-8 and the rear slag baffle plate 6-9 and the inner wall of the spiral heat exchanger 6 shell 6-1. A slag discharge valve 5 is provided at the feed port 6-4 of the spiral heat exchanger, and an ash discharge valve 10 is provided at the discharge port of the dust collector 9.

[0033] A scrap steel bin inlet valve 11 is provided on the pipeline connecting the scrap steel bin 12 and the spiral heat exchanger 6; a scrap steel bin outlet valve 13 is provided on the pipeline connecting the scrap steel bin 12 and the dust collector 9. There are one or more scrap steel bins 12. A roller press 2 is also provided on the slag tray 3, and the roller press 2 crushes the large slag.

[0034] In specific implementation, a device that utilizes the waste heat of steel slag recycles converter steel slag and transfers it to scrap steel. Its working process is as follows:

[0035] The slag from the converter enters the ladle 1, which is lifted by the overhead crane to the upper opening of the slag pan 3. The ladle 1 slowly pours the slag into the slag pan 3, which is inclined to the ground. The slag can flow down by itself. The large slag is crushed into small pieces after being rolled by the roller press 2. A screener 4 is provided at the outlet of the slag pan 3. The discharge port of the screener 4 is connected to the inlet of the spiral heat exchanger 6. Only small pieces of slag can enter the spiral heat exchanger 6. The large pieces of slag are screened out and fall into another ladle 1, and then re-enter the feed port of the slag pan 3 and are crushed by rollers again. The slag discharge valve 5 can ensure smooth discharge and seal the inlet. The slag flows toward the outlet driven by the spiral blades 6-10. At this time, the gas also enters from the air inlet 6-5 of the spiral heat exchanger with a certain wind pressure. The slag fully exchanges heat with the gas under the tumbling action of the spiral blades 6-10, and the slag temperature drops to about 500°C (the temperature may vary according to different hot stewing conditions), and is unloaded from the slag outlet 6-7 of the spiral heat exchanger. The slag outlet 6-7 of the spiral heat exchanger is also provided with a slag unloading valve 5 to ensure sealing while unloading the slag smoothly. The cooled slag enters the ladle 1 to the subsequent hot stewing process.

[0036] Since the gap between the spiral blade 6-10 of the spiral heat exchanger 6 and the shell 6-1 is generally small, the wind resistance will be very large when the hot gas passes through, and the direct contact increases the power consumption of the high-pressure blower 8. To solve this problem, a number of heat exchange tubes 6-11 are passed through the spiral blade 6-10, so that the gas no longer directly contacts the steel slag, but indirectly exchanges heat through the heat exchange tube 6-11, so that the flow can be smooth and the wind resistance can be reduced. In order to increase the heat exchange efficiency and the hot gas outlet temperature, the outer wall of the tube body 6-11-1 of the heat exchange tube 6-11 is provided with an outer heat dissipation rib 6-11-2, and the inner wall is provided with an inner radial heat dissipation rib 6-11-3. Taking the experiment of the heat exchange tube with a diameter of 159mm as an example, the total heat exchange area after adding 50 internal and external heat dissipation ribs reaches 15 times that of the light tube, which shortens the length of the spiral heat exchanger 6 to one third of the original, but the heat exchange effect is better. The experimental data show that under the working condition, when the original light tube heat exchanged heat, the outlet air temperature of the spiral heat exchanger 6 could only reach 500°C, while after replacing the heat exchange tube 6 with the heat dissipation rib, the outlet air temperature reached 680°C. Therefore, the present application not only reduces the volume of the spiral heat exchanger 6, reduces the equipment footprint, saves investment, but also greatly improves the heat exchange effect.

[0037] In the present application, a front slag baffle 6-8 and a rear slag baffle 6-9 are respectively arranged at the front and rear ends of the spiral blade 6-10. The position of the front slag baffle 6-8 should be a section after the air outlet 6-6, and the position of the slag baffle 6-9 should be a section before the air inlet 6-5, that is, the positions of the front slag baffle 6-8 and the rear slag baffle 6-9 should be between the air inlet 6-5 and the air outlet 6-6, ensuring that there is a certain space between the slag baffle and the front and rear ends of the spiral heat exchanger 6. The diameters of the front slag baffle 6-8 and the rear slag baffle 6-9 are slightly smaller than the inner net diameter of the spiral heat exchanger 6, but the gap between the two should be as small as possible to facilitate the rotation of the spiral blade 6-10.

[0038] The following is a detailed explanation using a 120t converter production example.

[0039] To increase the scrap ratio in the steelmaking process, the heat balance of the converter smelting process must be considered. Adding more scrap will increase the heat expenditure. Therefore, the higher the scrap preheating temperature, the more scrap ratio can be increased and the amount of molten iron can be reduced.

[0040] A 120t converter can produce about 15t of slag at a temperature of 1400℃. This device can be used to reduce the temperature of the slag to 500℃, releasing about 1.35x107KJ of heat. Each ladle 1 can hold 30t of slag. The smelting time for each furnace is about 45 minutes, and two furnaces are 90 minutes. The crane lifts the ladle 1 to the loading port of the slag pan 3 and then turns the ladle over. The slag slowly turns into the inlet of the slag pan 3. At this time, the roller press 2 is turned on. The slag is broken into small pieces after roller pressing. A dust collection device can be set near the roller press 2, and the smoke can be collected and processed. The crushed slag enters the spiral heat exchanger 6 through the slag discharge valve 4. The conveying capacity of the spiral heat exchanger 6 is about 20t / h. The slag is transported to the outlet under the drive of the spiral blades 6-10. The air volume of the high-pressure fan 8 in this supporting system is about 30,000m 3 / h. High-pressure air enters the wind quenching machine from the inlet, and the temperature is about 150°C. The spiral heat exchanger 6 can be divided into a preheating section and a reheating section from right to left. In the spiral heat exchanger 6, the gas exchanges heat with the steel slag, and the circulating hot gas passes through the heat exchange tube 6-11. The steel slag is also transported by the spiral blades 6-10, which can ensure that the steel slag and the heat exchange tube 6-11 are more fully exchanged. The temperature of the steel slag after cooling is about 500°C. If the slag discharge temperature is too high, the speed of the high-pressure fan 8 can be increased to increase the circulating air volume. The temperature of the hot gas can reach 600-700°C after heating. The high-temperature hot gas enters the scrap steel bin 12. Each 120t converter can add about 22t of scrap steel. The scrap steel bin 12 in this embodiment is designed to have a storage capacity of 22t. Two scrap steel bins are set in the embodiment. If the No. 1 scrap steel bin 12 is in operation, the inlet valve and outlet valve of the No. 2 scrap steel bin 12 are both closed. The hot air enters from the lower part of the scrap steel bin 12, and the wind speed in the steel bin is 2-3m / s. The hot air passes through the gaps between the scrap steel and fully exchanges heat with the scrap steel. After a cycle of heat exchange, the average temperature of the scrap steel can reach about 600℃. At this time, the loading of the No. 2 bin is completed, the bin cover is closed, the inlet and outlet scrap steel bin valves are opened, and the hot air enters for heat exchange; at the same time, the scrap steel bin inlet valve 11 and the scrap steel bin outlet valve 13 of the No. 1 bin are closed, the top cover of the scrap steel bin 12 is opened, and the scrap steel is hoisted out to enter the next process. The temperature of the hot air after cooling is about 150℃. At this time, the hot air contains a large amount of dust. After leaving the scrap steel bin 12, it first enters the dust collector 9 for dust removal, and then is pressurized by the high-pressure fan 8 again, and then heat exchanged in the spiral heat exchanger 6 to heat up, and then goes to the scrap steel bin 12 to preheat the scrap steel. In this way, the two scrap steel bins 12 work in a cycle to preheat the scrap steel to a predetermined temperature.

[0041] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for preheating scrap steel using waste heat from steel slag, characterized in that: include: a ladle containing steel slag; A slag pan, wherein the slag pan is inclined, the ladle is located above one end of the slag pan, and the ladle pours the slag into the slag pan; The screener has a feed port located below the other end of the slag pan, and the slag in the slag pan slides down into the screener under the action of gravity; The spiral heat exchanger comprises a shell, a motor reducer, a rotating shaft, a heat exchange tube, a spiral blade, a front slag baffle, a rear slag baffle, an air inlet of the spiral heat exchanger, an air outlet of the spiral heat exchanger, a feed port of the spiral heat exchanger and a slag outlet of the spiral heat exchanger. The motor reducer drives the rotating shaft and the spiral blade to rotate. The front slag baffle and the rear slag baffle are respectively inserted into the rotating shaft on both sides of the spiral blade; an air inlet bin is formed between one side of the rear slag baffle and the shell, and an air outlet bin is formed between one side of the front slag baffle and the shell; the feed port of the spiral heat exchanger is connected to the lower portion of the sifter. The material inlet is butted, and the slag outlet of the spiral heat exchanger is butted with the slag bag; the steel slag flows to the slag outlet of the spiral heat exchanger driven by the spiral blades, the air inlet of the spiral heat exchanger is located on the upper side of the shell of the air inlet bin, and is connected to the high-pressure fan by means of a pipeline, and the air outlet of the spiral heat exchanger is located on the lower side of the shell of the air outlet bin, the heat exchange pipe is parallelly penetrated on the spiral blades, and the two ends of the heat exchange pipe are respectively passed through the front slag baffle plate and the rear slag baffle plate to be connected with the air outlet bin and the air inlet bin; the gas in the spiral heat exchanger is opposite to the flow direction of the steel slag, so that the steel slag and the gas exchange heat; A scrap steel bin, wherein the scrap steel bin is filled with scrap steel, and an air inlet at the bottom of the scrap steel bin is connected to an air outlet of a spiral heat exchanger via a pipeline; the gas in the scrap steel bin moves from bottom to top, so that heat is exchanged between the scrap steel and the gas; A dust collector, wherein the air inlet of the dust collector is connected to the air outlet at the upper part of the scrap steel bin by means of a pipeline; and the air outlet of the dust collector is connected to the air inlet of the cooler by means of a pipeline; The air outlet of the cooler is connected to the high-pressure fan via a pipeline; The heat exchange tube comprises a tube body, external heat dissipation ribs and internal heat dissipation ribs; the external heat dissipation ribs are evenly distributed on the outer periphery of the tube body, and the internal heat dissipation ribs are evenly distributed inside the tube body in a radial shape; There is a gap between the front slag baffle plate and the rear slag baffle plate and the inner wall of the spiral heat exchanger shell; A slag discharge valve is provided at the feed inlet of the spiral heat exchanger, and an ash discharge valve is provided at the discharge inlet of the dust collector.

2. The device for preheating scrap steel using waste heat of slag according to claim 1, characterized in that: A scrap steel bin inlet valve is arranged on the pipeline connecting the scrap steel bin and the spiral heat exchanger; and a scrap steel bin outlet valve is arranged on the pipeline connecting the scrap steel bin and the dust collector.

3. The device for preheating scrap steel using waste heat of slag according to claim 2, characterized in that: The number of the scrap steel bins is one or more.

4. The device for preheating scrap steel using waste heat of slag according to claim 1, characterized in that: A roller press is also provided on the slag tray, and the roller press crushes the large pieces of slag.

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