A system and method for comprehensive utilization of steel slag waste heat recovery and resource

Abstract

The present invention relates to a system and method for waste heat recovery and resource comprehensive utilization of steel slag, belonging to the technical field of steel slag recovery. It includes an exchange heat device, a pressure thermal soaking device, a mixing device, a grinding device and a magnetic separation device arranged in sequence along the flow direction of the steel slag. The exchange heat device uses molten salt heat exchange for the primary cooling of the steel slag, and the exchange heat device is connected with a molten salt steam device. The pressure thermal soaking device is used for the secondary cooling of the steel slag, using water cooling, and the pressure thermal soaking device is connected with a steam-water heat exchange device. The cooling medium outlet of the steam-water heat exchange device is communicated with the cooling medium inlet of the molten salt steam device. After the steel slag is cooled in two stages, it enters the mixing device to be uniformly mixed with the admixture in proportion, then is ground into fine powder by the grinding device, and then the iron powder is separated from the fine powder by the magnetic separation device. The present invention realizes the dual utilization of waste heat recovery and resource of high-temperature steel slag, and at the same time solves the environmental pollution problem of high-temperature steel slag.

Description

Technical Field

[0001] The invention belongs to the technical field of steel slag recovery, and relates to a system and method for recovering waste heat from steel slag and comprehensive resource utilization. Background Art

[0002] Steel slag has a huge stock, complex composition, high temperature, and rich waste heat and waste energy resources. How to effectively utilize them has always been a major problem that has plagued steel companies. High-temperature steel slag produces about 80-120 million tons per year, with an utilization rate of less than 30%. The furnace temperature is about 1400°C or above, and it contains rich iron elements, which urgently needs to be efficiently recycled. Although there are solutions for the resource treatment of high-temperature liquid steel slag at home and abroad, either only the recovery of the heat energy of high-temperature liquid steel slag is considered, resulting in a waste of steel slag resources, or only the resource utilization of steel slag is considered, used as cement and other building materials, but the recovery of thermal energy resources is not sufficient. Therefore, how to obtain efficient steel slag waste heat recovery and simultaneously realize iron resource recovery and steel slag resource utilization is an urgent problem to be solved. Summary of the invention

[0003] In view of this, the purpose of the present application is to provide a system and method for waste heat recovery and comprehensive resource utilization of steel slag, so as to achieve dual utilization of waste heat recovery and resource utilization of high-temperature steel slag.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A system for recovering and comprehensively utilizing waste heat from steel slag comprises a heat exchange device, a pressure heat stuffing device, a mixing device, a grinding device and a magnetic separation device which are sequentially arranged along the flow direction of the steel slag; the heat exchange device adopts molten salt heat exchange and is used for primary cooling of the steel slag, and the heat exchange device is connected with a molten salt steam device to realize the recycling of the molten salt used in the heat exchange device; the pressure heat stuffing device is used for secondary cooling of the steel slag and adopts water cooling, and the pressure heat stuffing device is connected with a steam-water heat exchange device to realize the recycling of cooling water used in the pressure heat stuffing device; the cooling medium outlet of the steam-water heat exchange device is connected with the cooling medium inlet of the molten salt steam device to realize the secondary heating and utilization of the cooling medium used in the steam-water heat exchange device.

[0006] Optionally, the heat exchange device adopts a heat exchange method in which the heat exchange tubes are in direct contact with the high-temperature steel slag, and the heat exchange tubes are arranged in a cross-row countercurrent at the inlet of the heat exchange device.

[0007] Optionally, the molten salt steam device adopts a shell and tube heat exchanger, the molten salt and high-temperature water are heat exchanged in a jacketed tube type, the heat exchange tubes are arranged in countercurrent, and a steam collection pipe is provided on the top to collect the steam and send it to the steam network.

[0008] Optionally, the pressurized thermal soaking device includes a pressurized thermal soaking bin. An openable bin cover is provided above the pressurized thermal soaking bin. A plurality of nozzles communicating with the water inlet of the pressurized thermal soaking device are provided on the lower side of the bin cover. The water inlet of the pressurized thermal soaking device is communicated with the water outlet of the steam-water heat exchange device. A steel slag discharge port is provided at the bottom of the pressurized thermal soaking bin. A steam outlet communicating with the steam inlet of the steam-water heat exchange device is opened at the upper part of the pressurized thermal soaking bin.

[0009] Optionally, the bin cover of the pressurized thermal soaking device is of a push-pull type.

[0010] Optionally, a hot water utilization branch is further connected to the pipeline connecting the cooling medium outlet of the steam-water heat exchange device and the cooling medium inlet of the molten salt steam device.

[0011] Optionally, the steam-water heat exchange device adopts a shell-and-tube heat exchanger. The normal temperature water exchanges heat with the dirty steam through a sleeve type, and the heat exchange tubes are arranged in a countercurrent manner. The heated water is transported to the molten salt steam device through a part of the pipeline, and the other part is transported to the central heating system through the hot water utilization branch.

[0012] Optionally, the mixing device includes a mixer, and a steel slag bin, a blast furnace slag bin, and a fly ash bin with regulating valves at the feeding ports and arranged side by side above the conveyor belt. The output end of the conveyor belt faces the feeding port of the mixer so that the materials on the conveyor belt enter the mixer.

[0013] A method for steel slag waste heat recovery and resource comprehensive utilization, applying the system for steel slag waste heat recovery and resource comprehensive utilization as described above. The high-temperature steel slag is added to the heat exchange device, and after heat exchange with the liquid molten salt in the heat exchange device, the temperature drops to 800 - 1000 °C, and then enters the pressurized thermal soaking device. After being cooled by water, the temperature drops below 200 °C, and then it is mixed with blast furnace slag and fly ash in proportion and ground into fine powder, and then the iron powder and ultrafine powder slag are separated by magnetic separation; the liquid molten salt used in the heat exchange device is passed into the molten salt steam device after heat exchange, and after heat exchange and temperature reduction, it is used in the heat exchange device again; the normal temperature water used in the pressurized thermal soaking device is passed into the steam-water heat exchange device after heat exchange, and after heat exchange and temperature reduction to normal temperature, it is used in the pressurized thermal soaking device again. At the same time, the high-temperature water generated by the steam-water heat exchange device enters the molten salt steam device to form high-temperature steam.

[0014] Optionally, it specifically includes the following steps:

[0015] S1: The high-temperature steel slag directly enters the heat exchange device and exchanges heat with the liquid molten salt in the pipeline of the heat exchange device. The temperature drops to 800 - 1000 °C. The 260 - 300 °C liquid molten salt used in the heat exchange device rises to 540 - 580 °C after heat exchange and is passed into the molten salt steam device. After heat exchange and temperature reduction to 260 - 300 °C, it is used in the heat exchange device again;

[0016] S2: After the steel slag cooled by the heat exchange device reaches a certain volume, add the cooled steel slag to the pressure heat soaking device, and use normal temperature water spray to cool the steel slag below 200 °C; the dirty steam generated after the normal temperature water used in the pressure heat soaking device is heat exchanged is introduced into the steam-water heat exchange device, and after heat exchange and cooling to normal temperature, it is used in the pressure heat soaking device again. At the same time, a part of the 80-100 °C high-temperature water generated by the steam-water heat exchange device enters the molten salt steam device for further heating to form 350-500 °C high-temperature steam and is transported to the external network, and the other part enters the heating system;

[0017] S3: Dry the steel slag treated by the pressure heat soaking device, then mix it in the ratio of 40% steel slag, 40% blast furnace slag, and 20% fly ash and grind it into fine powder, and then magnetically separate iron powder, and recycle the remaining slag powder.

[0018] The beneficial effects of the present invention are as follows: It realizes the dual utilization of waste heat recovery and resource utilization of high-temperature steel slag, realizes the whole-process treatment of high-temperature steel slag, can efficiently recover the sensible heat of high-temperature steel slag, solves the environmental pollution problem, and can make full use of the subsequent value of steel slag. It can not only recover iron powder, but also use the remaining slag powder as building materials. It is a mature and perfect high-temperature steel slag recovery system that can be applied to industrial production.

[0019] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, they will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0021] Figure 1 is a flow chart of a system for waste heat recovery and resource comprehensive utilization of steel slag according to the present invention;

[0022] Figure 2 is a flow chart of steel slag blending and iron powder separation according to the present invention.

[0023] Reference numerals: heat exchange device 1, molten salt steam device 2, pressure heat soaking device 3, steam-water heat exchange device 4, mixer 5, grinding device 6, magnetic separation device 7, dryer 8, blast furnace slag bin 9, steel slag bin 10, fly ash bin 11. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0025] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams rather than actual diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0026] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0027] Please refer to Figures 1 to 2 , a system for comprehensive utilization of steel slag waste heat recovery and resource utilization, including a heat exchange device 1, a pressurized heat soaking device 3, a mixing device, a grinding device 6, and a magnetic separation device 7 arranged in sequence along the flow direction of the steel slag; the heat exchange device 1 uses molten salt heat exchange for the primary cooling of the steel slag. The heat exchange device 1 is connected to a molten salt steam device 2 to realize the recycling of the molten salt for the heat exchange device 1; the pressurized heat soaking device 3 is used for the secondary cooling of the steel slag, using water cooling. The pressurized heat soaking device 3 is connected to a steam-water heat exchange device 4 to realize the recycling of the cooling water for the pressurized heat soaking device 3; the cooling medium outlet of the steam-water heat exchange device 4 is communicated with the cooling medium inlet of the molten salt steam device 2 to realize the secondary heating utilization of the cooling medium for the steam-water heat exchange device 4; the mixing device is used for mixing the steel slag and the admixture to form a uniform mixture; the grinding device 6 is used for grinding the mixture to form fine powder; the magnetic separation device 7 is used for separating iron powder from the fine powder.

[0028] The mixing device of the present invention includes a mixer 5, and a steel slag bin 10, a blast furnace slag bin 9, and a fly ash bin 11 which are arranged side by side above the conveyor belt with regulating valves provided at their discharge ports. The output end of the conveyor belt faces the feed port of the mixer 5 so that the materials on the conveyor belt enter the mixer 5. The grinding device 6 is preferably a vertical mill, and the magnetic separation device 7 is a magnetic separator, which has a magnetic powder outlet and a powder-slag outlet.

[0029] In the present invention, after the steel slag is cooled in two stages, it enters the mixing device to be mixed evenly with the blast furnace slag and fly ash, then is ground into fine powder by the grinding device 6, and then the iron powder is separated from the fine powder by the magnetic separation device 7.

[0030] Preferably, the heat exchange device 1 adopts a method of directly contacting and exchanging heat between the heat exchange tubes and high-temperature solid slag particles (steel slag), and the heat exchange tubes at the inlet of the heat exchange device 1 are arranged in a staggered and countercurrent manner.

[0031] Preferably, the molten salt steam device 2 adopts a shell-and-tube heat exchanger, and the molten salt exchanges heat with the high-temperature water in a casing type, and the heat exchange tubes are arranged in a countercurrent manner, and a steam collection pipeline is provided above to collect and send the steam to the steam pipe network.

[0032] Preferably, the pressure thermal soaking device 3 includes a pressure thermal soaking bin, and an openable bin cover is provided above the pressure thermal soaking bin. Several nozzles communicating with the water inlet of the pressure thermal soaking device 3 are provided on the lower side of the bin cover. The water inlet of the pressure thermal soaking device 3 is communicated with the water outlet of the steam-water heat exchange device 4. A steel slag discharge port is provided at the bottom of the pressure thermal soaking bin, and a steam outlet communicating with the steam inlet of the steam-water heat exchange device 4 is opened at the upper part of the pressure thermal soaking bin; the bin cover of the pressure thermal soaking device 3 is a push-pull type.

[0033] Preferably, a hot water utilization branch is also connected to the pipeline connecting the cooling medium outlet of the steam-water heat exchange device 4 and the cooling medium inlet of the molten salt steam device 2.

[0034] Preferably, the steam-water heat exchange device 4 adopts a shell-and-tube heat exchanger, and the normal temperature water exchanges heat with the dirty steam in a casing type, and the heat exchange tubes are arranged in a countercurrent manner. The heated water is transported to the molten salt steam device 2 through a part of the pipeline, and the other part is transported to the central heating system through the hot water utilization branch.

[0035] A method for comprehensive utilization of waste heat recovery and resource recovery from steel slag. Applying the system for comprehensive utilization of waste heat recovery and resource recovery from steel slag described above, the high-temperature steel slag is added to the heat exchange device 1 and undergoes heat exchange with the liquid molten salt in the heat exchange device 1, and the temperature drops to 800 - 1000 °C. Then it enters the pressure thermal soaking device 3, and after being cooled by water, the temperature drops below 200 °C. Then it is mixed with blast furnace slag and fly ash in proportion and ground into fine powder, and then the iron powder and ultrafine powder slag are separated by magnetic separation; the liquid molten salt used for the heat exchange device 1 is passed into the molten salt steam device 2 after heat exchange, and after heat exchange and temperature reduction, it is used for the heat exchange device 1 again; the normal temperature water used for the pressure thermal soaking device 3 is passed into the steam-water heat exchange device 4 after heat exchange, and after heat exchange and temperature reduction to normal temperature, it is used for the pressure thermal soaking device 3 again. At the same time, the high-temperature water generated by the steam-water heat exchange device 4 enters the molten salt steam device 2 to form high-temperature steam.

[0036] Optionally, it specifically includes the following steps:

[0037] S1: The high-temperature steel slag directly enters the heat exchange device 1 and undergoes heat exchange with the liquid molten salt in the pipeline of the heat exchange device 1, and the temperature drops to 800 - 1000 °C. The 260 - 300 °C liquid molten salt used for the heat exchange device 1 rises to 540 - 580 °C after heat exchange and is passed into the molten salt steam device 2. After heat exchange and temperature reduction to 260 - 300 °C, it is used for the heat exchange device 1 again;

[0038] S2: After the steel slag cooled by the heat exchange device 1 reaches a certain volume, the cooled steel slag is added to the pressure thermal soaking device 3, and the steel slag is cooled to below 200 °C by spraying normal temperature water; the dirty steam generated after the normal temperature water used for the pressure thermal soaking device 3 undergoes heat exchange is passed into the steam-water heat exchange device 4, and after heat exchange and temperature reduction to normal temperature, it is used for the pressure thermal soaking device 3 again. At the same time, a part of the 80 - 100 °C high-temperature water generated by the steam-water heat exchange device 4 enters the molten salt steam device 2 for further heating to form 350 - 500 °C high-temperature steam and is transported to the external network, and the other part enters the heating system;

[0039] S3: The steel slag treated by the pressure thermal soaking device 3 is dried, and then ground into fine powder according to the proportion of 40% steel slag, 40% blast furnace slag, and 20% fly ash, and then the iron powder is separated by magnetic separation, and the remaining slag powder is recycled.

[0040] In view of the problems that the waste heat and energy of high-temperature steel slag have not been recovered and utilized and the resource utilization of steel slag, the present invention proposes a system and method for comprehensive utilization of waste heat recovery and resource utilization of steel slag. The 1550°C high-temperature steel slag passes through the heat exchange device 1, exchanges heat with liquid molten salt, and is cooled to 800-1000°C, and then enters the pressurized heat soaking device 3. After being cooled by water, the temperature drops below 200°C, and it enters the mixing device in proportion with blast furnace slag and fly ash. After mixing, it enters the grinding device 6 to be ground into fine powder, and iron powder and ultrafine powder slag are separated by magnetic separation, realizing the resource utilization of steel slag. The normal temperature water used for heat exchange is heated to 80-100°C through the steam-water heat exchange device 4. One part enters the molten salt steam device 2 to form steam at 350-500°C, and the other part enters the heating system, realizing the waste heat recovery of high-temperature steel slag. The present invention can efficiently recover the sensible heat of high-temperature steel slag, realize resource utilization, can recover iron powder and use the remaining slag powder as building materials, and is a mature and perfect high-temperature steel slag recovery system applicable to industrial production.

[0041] Example 1

[0042] A system for comprehensive utilization of waste heat recovery and resource utilization of steel slag includes a heat exchange device 1, a pressurized heat soaking device 3, a mixing device, a grinding device 6, and a magnetic separation device 7 arranged in sequence along the flow direction of steel slag; the mixing device includes a steel slag bin 10, a blast furnace slag bin 9, a fly ash bin 11, a mixer 5, a conveyor belt and other devices; the grinding device 6 includes a vertical mill, a conveyor belt and other devices.

[0043] The heat exchange device 1 uses molten salt heat exchange for the primary cooling of steel slag, and the heat exchange device 1 is connected to a molten salt steam device 2; the molten salt steam device 2: includes a molten salt inlet: communicated with the molten salt outlet of the heat exchange device 1; a molten salt outlet: communicated with the molten salt inlet of the heat exchange device 1; a cooling medium inlet; a cooling medium outlet; the pressurized heat soaking device 3: for the secondary cooling of steel slag, including a pressurized heat soaking bin, the upper part of the pressurized heat soaking bin is provided with an openable cover, the lower side of the cover is provided with a plurality of nozzles communicated with the water inlet, the bottom of the pressurized heat soaking bin is provided with a steel slag discharge port, and the upper part of the pressurized heat soaking bin is provided with a steam outlet; the pressurized heat soaking device 3 is connected to a steam-water heat exchange device 4; the steam-water heat exchange device 4: includes a steam inlet: communicated with the steam outlet of the pressurized heat soaking device 3; a water outlet: communicated with the water inlet of the pressurized heat soaking device 3; a cooling medium inlet: communicated with a water source: a cooling medium outlet: communicated with the cooling medium inlet of the molten salt steam device 2.

[0044] After two-stage cooling, the steel slag enters the mixing device to be mixed evenly with blast furnace slag and fly ash in proportion, then is ground into fine powder by the grinding device 6, and then iron powder is separated from the fine powder by the magnetic separation device 7.

[0045] The heat exchange device 1 uses the method of direct contact heat exchange between heat exchange tubes and high-temperature solid slag particles. At the inlet of the heat exchange device 1, the heat exchange tubes are arranged in a staggered pattern and counter-currently. The molten salt steam device 2 uses a shell-and-tube heat exchanger, where molten salt exchanges heat with a high-temperature water jacket in a counter-current arrangement of heat exchange tubes, and a steam collection pipeline is equipped above to collect and send the steam out to the steam pipe network. The pressurized heat soaking device 3 has a push-pull type cover on the top, with multiple spray devices below the cover and a water inlet for circulating water above. The cover is periodically opened to load high-temperature steel slag. There is a steel slag discharge port below the bin, and in addition, there is a dirty steam collection pipeline above the bin. The steam-water heat exchange device 4 uses a shell-and-tube heat exchanger and the method of sleeve heat exchange between normal temperature water and dirty steam, with the heat exchange tubes arranged in a counter-current pattern. The heated water is transported through pipelines, part of it to the molten salt steam system and part of it to the central heating system. The mixing device includes a steel slag bin 10, a blast furnace slag bin 9, and a fly ash bin 11. A regulating valve is installed at the feeding port, and a conveyor belt is equipped below the bin, which is connected to the mixer 5. The grinding device 6 is a vertical mill, and the magnetic separation device 7 is behind the vertical mill. Both are connected to the mixer 5 through a conveyor belt.

[0046] This comprehensive utilization system can be divided into four parts according to the medium: the steel slag recovery system, the steam generation system, the dirty water-steam circulation system, and the liquid molten salt circulation system.

[0047] After the high-temperature steel slag is cooled by the heat exchange device 1, it then enters the pressurized heat soaking device 3, is cooled to below 200 °C by spraying water, and then enters the mixing device. After drying, it is mixed with blast furnace slag and fly ash in proportion, and then enters the grinding device 6 and the magnetic separation device 7 to form fine powder. The iron powder and ultra-fine powder slag are separated by magnetic separation. The whole process is the steel slag recovery system.

[0048] The normal temperature water is heated to 90 °C by the steam-water heat exchange device 4. Part of it enters the molten salt steam device 2 to form steam at 350 - 500 °C, and part of it enters the heating system. This process is the steam generation system.

[0049] The steam outlet of the pressurized heat soaking device 3 is connected to the steam inlet of the steam-water heat exchange device 4, and the normal temperature water inlet of the pressurized heat soaking device 3 is connected to the dirty water outlet of the steam-water heat exchange device 4 to form the dirty water-steam circulation system.

[0050] The molten salt outlet of the heat exchange device 1 is connected to the molten salt inlet of the molten salt steam device 2, and the molten salt inlet of the heat exchange device 1 is connected to the molten salt outlet of the molten salt steam device 2 to form the liquid molten salt circulation system.

[0051] Example 2

[0052] A method for steel slag waste heat recovery and resource comprehensive utilization, including a steel slag recovery method and a waste heat utilization method (steam generation method). The implementation process includes the following steps:

[0053] (1) Slag recovery method:

[0054] Step 1: Heat exchange process between high temperature slag and molten salt:

[0055] This process is mainly completed by the heat exchange device 1 to achieve the initial cooling of the high-temperature molten slag. The molten salt is connected to the molten salt steam device 2, and the cooled slag enters the pressurized hot stuffy device 3. The method is: the high-temperature slag at about 1550°C directly enters the heat exchange device 1, and the high-temperature solid slag falls directly and exchanges heat with the liquid molten salt in the heat exchange tube in countercurrent. The slag can be initially cooled to 800-1000°C and sent to the intermediate silo from the lower discharge port. At the same time, the molten salt at about 280°C enters from the bottom, is heated to 560°C through heat exchange, and directly enters the molten salt steam device 2 through the pipeline. The molten salt steam device 2 exchanges heat with water to form molten salt at about 280°C and then returns to the heat exchange device 1, realizing the recycling of the molten salt;

[0056] Step 2: Medium temperature slag-water steam waste heat recovery process:

[0057] This process is mainly completed by the pressurized hot stuffing device 3, which reduces the temperature of the steel slag to below 200°C. The steel slag enters the mixing device, and the water and steam are connected to the steam-water heat exchange device 4. The method is: after the steel slag in the intermediate silo reaches a certain volume, push open the push-pull bin cover above the pressurized hot stuffing device 3, pour the cooled steel slag into the bin, and then close the bin cover. The circulating water enters the top through the spraying device and sprays onto the steel slag below to further cool the steel slag to below 200°C. At the same time, the circulating water encounters the high-temperature steel slag to produce dirty steam of 110°C, which enters the nearby steam-water heat exchange device 4 through the steam collection pipe in the bin, exchanges heat with normal temperature water in the steam-water heat exchange device 4, cools to dirty water at room temperature, and then returns to the pressurized hot stuffing device 3 to achieve the recycling of dirty water-steam;

[0058] Step 3: Slag mixing process:

[0059] This process is mainly completed by the mixing device to achieve the proportion of steel slag, blast furnace slag and fly ash. The method is that after the pressure and heat device 3 reaches the processing time, the wet slag is discharged from the discharge port below, and after drying, it is placed in the steel slag silo 10, and the blast furnace slag silo 9 and fly ash silo 11 are arranged next to it. By controlling the silo valve, 40% of steel slag, 40% of blast furnace slag and 20% of fly ash are placed on the conveyor belt and transported to the mixer 5 for full mixing.

[0060] Step 4: Slag recycling process:

[0061] This process is mainly completed by the grinding device 6 and the magnetic separation device 7, realizing the refinement of the mixture, separating iron powder and ultra-fine slag powder, and the ultra-fine slag powder can be used as building materials. The method is as follows: the mixture in the mixing device is directly sent into the vertical mill through the conveyor belt to form ultra-fine powder, and then the iron powder is separated by the magnetic separator. The remaining slag powder is stored in the finished product bin or transported out by the transport vehicle.

[0062] (2) Preheating utilization method:

[0063] Step 1: Steam-water heat exchange process:

[0064] This process is mainly completed by the steam-water heat exchange device 4 unit, heating the normal temperature water to 90 °C high-temperature water that can be used for heating. The method is as follows: the normal temperature water enters the steam-water heat exchange device 4, that is, the shell-and-tube heat exchanger. The normal temperature water and the dirty steam are heat-exchanged through the sleeve type, and can be heated to 90 °C, while cooling the 110 °C dirty steam to normal temperature. Due to the limited heat exchange capacity of the next unit, part of the 90 °C high-temperature water enters the molten salt steam device 2 to be further heated into steam, and the other part enters the heating pipeline;

[0065] Step 2: Molten salt heat exchange process:

[0066] This process is mainly completed by the molten salt steam device 2, realizing the generation of steam. The method is as follows: the about 90 °C high-temperature water directly enters the molten salt steam device 2, that is, the shell-and-tube heat exchanger. The high-temperature water and the molten salt are heat-exchanged in a sleeve type, and steam at 350 - 500 °C can be generated and transported to the external network, while the molten salt at about 560 °C is cooled to 280 °C.

[0067] In the present invention, the molten salt outlet of the heat exchange device 1 is connected to the molten salt inlet of the molten salt steam device 2, and the molten salt inlet of the heat exchange device 1 is connected to the molten salt outlet of the molten salt steam device 2, forming a liquid molten salt circulation system.

[0068] In the present invention, the steam outlet of the pressure hot stamping device 3 is connected to the steam inlet of the steam-water heat exchange device 4, and the normal temperature water inlet of the pressure hot stamping device 3 is connected to the dirty water outlet of the steam-water heat exchange device 4, forming a dirty water-steam circulation system.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A system for comprehensive utilization of waste heat recovery and resource of steel slag, characterized in that: It includes a heat exchange device, a pressurized heat soaking device, a mixing device, a grinding device and a magnetic separation device arranged in sequence along the flow direction of the steel slag; The heat exchange device uses molten salt heat exchange for the primary cooling of the steel slag. The heat exchange device is connected with a molten salt steam device to realize the recycling of the molten salt used in the heat exchange device; The pressurized heat soaking device is used for the secondary cooling of the steel slag, using water cooling. The pressurized heat soaking device is connected with a steam-water heat exchange device to realize the recycling of the cooling water used in the pressurized heat soaking device; wherein, The water inlet of the pressurized heat soaking device is communicated with the water outlet of the steam-water heat exchange device, and a steam outlet communicated with the steam inlet of the steam-water heat exchange device is arranged at the upper part of the pressurized heat soaking bin; The cooling medium outlet of the steam-water heat exchange device is communicated with the cooling medium inlet of the molten salt steam device to realize the secondary heating utilization of the cooling medium used in the steam-water heat exchange device; a hot water utilization branch is also connected to the pipeline between the cooling medium outlet of the steam-water heat exchange device and the cooling medium inlet of the molten salt steam device. The water heated by the steam-water heat exchange device is transported to the molten salt steam device through a pipeline in part, and the other part is transported to the central heating system through the hot water utilization branch; The heat exchange device adopts the way of direct contact heat exchange between the heat exchange tubes and the high-temperature steel slag, and the heat exchange tubes at the inlet of the heat exchange device are arranged in a staggered and countercurrent manner; The steam-water heat exchange device adopts a shell-and-tube heat exchanger, and the normal temperature water and the dirty steam are in a sleeve heat exchange, and the heat exchange tubes are arranged in a countercurrent manner.

2. The system for comprehensive utilization of steel slag waste heat recovery and resourceization according to claim 1, wherein: The molten salt steam device adopts a shell-and-tube heat exchanger, and the molten salt and the high-temperature water are in a sleeve heat exchange, and the heat exchange tubes are arranged in a countercurrent manner. A steam collection pipeline is arranged above to collect and send the steam to the steam pipe network.

3. A system for comprehensive utilization of steel slag waste heat recovery and resourceization according to claim 1, characterized in that: The pressurized heat soaking device includes a pressurized heat soaking bin. A lid that can be opened is arranged above the pressurized heat soaking bin. A plurality of nozzles communicated with the water inlet of the pressurized heat soaking device are arranged on the lower side of the lid, and a steel slag discharge port is arranged at the bottom of the pressurized heat soaking bin.

4. A system for comprehensive utilization of steel slag waste heat recovery and resourceization according to claim 3, characterized in that: The lid of the pressurized heat soaking device is of a push-pull type.

5. A system for comprehensive utilization of steel slag waste heat recovery and resourceization according to claim 1, characterized in that: The mixing device includes a mixer, and a steel slag bin, a blast furnace slag bin and a fly ash bin with regulating valves arranged at the feeding ports and arranged side by side above the conveyor belt. The output end of the conveyor belt faces the feeding port of the mixer so that the materials on the conveyor belt enter the mixer.

6. A method for comprehensive utilization of waste heat recovery and resource utilization of steel slag, characterized in that: Applying a system for comprehensive utilization of waste heat recovery and resource of steel slag as described in any one of claims 1 to 5, adding high-temperature steel slag to the heat exchange device, after heat exchange with the liquid molten salt of the heat exchange device, the temperature drops to 800 - 1000 °C, and then enters the pressurized heat soaking device, and after being cooled by water, it drops to below 200 °C, and then is mixed with blast furnace slag and fly ash in proportion and ground into fine powder, and then the iron powder and ultra-fine powder slag are separated by magnetic separation; the liquid molten salt used in the heat exchange device is introduced into the molten salt steam device after heat exchange, and after heat exchange and temperature reduction, it is used in the heat exchange device again; the normal temperature water used in the pressurized heat soaking device is introduced into the steam-water heat exchange device after heat exchange, and after heat exchange and temperature reduction to normal temperature, it is used in the pressurized heat soaking device again. At the same time, the high-temperature water generated by the steam-water heat exchange device enters the molten salt steam device to form high-temperature steam.

7. A method for comprehensive utilization of steel slag waste heat recovery and resourceization according to claim 6, characterized in that, Specifically, it includes the following steps: S1: The high-temperature steel slag directly enters the heat exchange device and exchanges heat with the liquid molten salt in the pipeline of the heat exchange device, and the temperature drops to 800 - 1000 °C. The liquid molten salt at 260 - 300 °C for the heat exchange device rises to 540 - 580 °C after heat exchange and then enters the molten salt steam device. After heat exchange and cooling to 260 - 300 °C, it is used in the heat exchange device again; S2: After the steel slag cooled by the heat exchange device reaches a certain volume, the cooled steel slag is added to the pressure thermal soaking device, and the steel slag is cooled to below 200 °C by spraying normal temperature water; the dirty steam generated after the normal temperature water for the pressure thermal soaking device exchanges heat is introduced into the steam-water heat exchange device. After heat exchange and cooling to normal temperature, it is used in the pressure thermal soaking device again. At the same time, a part of the 80 - 100 °C high-temperature water generated by the steam-water heat exchange device enters the molten salt steam device for further heating to form high-temperature steam at 350 - 500 °C and is transported to the external network, and the other part enters the heating system; S3: The steel slag treated by the pressure thermal soaking device is dried, and then ground into fine powder according to the proportion of 40% steel slag, 40% blast furnace slag, and 20% fly ash. Then, iron powder is separated by magnetic separation, and the remaining slag powder is recycled.

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