A method for conditioning and modifying a steelmaking hot desulfurization slag

Abstract

The application discloses a method for modifying and adjusting hot-state desulfurization slag of steelmaking, which comprises the following steps: mixing hot-state molten desulfurization slag and casting residue or mixed liquid casting residue in a hot-state adjusting and conditioning pool, and changing the caking and difficult-to-handle characteristics of the molten desulfurization slag into easy-to-handle modified slag for subsequent disposal. The application solves the technical problem of large lumps of slag and iron in existing steel enterprises, and has strong operability and no safety problem.

Description

Technical Field

[0001] This invention relates to metallurgical slag treatment technology, and more specifically, to a method for conditioning and modifying hot desulfurization slag from steelmaking. Background Technology

[0002] In the desulfurization process of steelmaking in steel enterprises, molten iron undergoes pretreatment, starting with desulfurization and slag removal. After the sulfur content in the molten iron is reduced to a certain level, it is directly fed into the converter for steelmaking. The desulfurization slag is directly removed into the slag ladle. Generally, the amount of desulfurization slag generated in molten iron accounts for about 2% of the total amount of molten iron. During the removal process, iron is inevitably carried out with the desulfurization slag, resulting in a mixture of slag and iron. Each ladle contains desulfurization slag from seven or eight heats simultaneously, causing a large amount of desulfurization slag and iron to mix together, eventually forming a large clump of slag and iron. Traditional desulfurization slag disposal processes involve soaking the slag in water followed by cutting, which uses oxygen cutting. This process is not only costly but also has a very negative environmental impact.

[0003] Therefore, new ideas and methods are needed to overcome slag-iron agglomeration and facilitate slag-iron separation. Hot tempering and modification of desulfurization slag in molten iron to prevent the formation of large slag-iron clumps has become a new technological process.

[0004] Existing patent applications, such as patent application number 202110198166.9, disclose a method for hot tempering and modification of molten iron desulfurization slag. This method involves mixing hot molten iron desulfurization slag in a slag pot with liquid converter slag for hot tempering, thereby changing the agglomerated and difficult-to-handle characteristics of the molten iron desulfurization slag. However, this patented technology actually involves pouring liquid converter slag into the desulfurization slag. Due to the high temperature and strong oxidizing properties of the converter slag, a violent carbon-oxygen reaction occurs with the desulfurization slag, causing the entire slag to quickly overflow from the pot. This can easily burn cables or cause safety accidents, making continuous operation difficult.

[0005] For example, patent application number 201410757334.3 discloses a method for modifying and treating injected desulfurization slag. This method requires filling the converter slag receiving hopper with injected desulfurization slag, then transporting it to the foundry slag yard. The full hopper is then evenly mixed into 2-5 empty slag hoppers. These slag hoppers, now mixed with injected desulfurization slag, are placed on the converter slag discharge car and transported to the converter to receive molten steel slag. However, this patented technology requires the crane's lug spacing and hook width to accommodate the trunnions of both the desulfurization slag hopper and the foundry slag hopper. Typically, the two hoppers in steel and metallurgical enterprises differ significantly in size, and the trunnion spacing is not uniform. Furthermore, the converter slag discharge time is limited, and logistics are tightly coordinated, making it impossible to dump foundry slag into multiple slag hoppers. This would significantly increase the converter slag discharge time and the operational difficulty of coordinating slag discharge between the slag hopper car and the converter, making it practically infeasible.

[0006] For example, patent application number 201810164154.2 discloses a method and application for hot mixing of desulfurization slag and foundry residue. The application is located in a dry slag-sinking pit. The method involves pouring KR desulfurization slag into the pit, then spreading liquid foundry residue on the surface of the KR desulfurization slag, followed by slag turning and mixing, aiming to obtain mixed slag and iron within the pit. However, this method also presents the problem of the crane needing to adapt to both the KR desulfurization slag tank and the foundry residue tank. Furthermore, the actual effective yield of mixed slag and iron using this patented technology is not very high because there is no reaction space or container; simply pouring liquid foundry residue onto the KR desulfurization slag results in significant heat dissipation and a limited reaction area between the two slags, making the reaction effect difficult to achieve. Furthermore, turning and mixing the slag after it has landed requires the use of mobile machinery such as forklifts, but any steel machinery cannot be in contact with high-temperature slag for extended periods, making it practically difficult to operate and failing to achieve the desired modification. Summary of the Invention

[0007] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a method for conditioning and modifying hot desulfurization slag in steelmaking, which solves the technical problem of large lumps of slag and iron in existing steel enterprises, and is highly operable and has no safety issues.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for conditioning and modifying hot desulfurization slag in steelmaking;

[0010] Hot desulfurization slag from molten iron and mixed liquid foundry residue are subjected to hot tempering in a hot pouring pool. The relatively large space of the hot pouring pool is used to change the agglomerated and difficult-to-handle characteristics of the molten iron desulfurization slag, transforming it into a modified slag that is easier to handle for subsequent processing.

[0011] Preferably, the method for conditioning and modifying hot desulfurization slag in steelmaking specifically includes the following steps:

[0012] S1, set up a transport line for returning residual slag tanks to the desulfurization process;

[0013] S2, a mixing station for molten iron desulfurization slag and casting residue is set up in the desulfurization process;

[0014] S3, a desulfurization slag pot baking station is set up in the desulfurization process, and induction heating or flame baking is used to bake or reheat the molten iron desulfurization slag pot.

[0015] S4, a ladle-carrying vehicle is configured at the desulfurization slag removal station of molten iron;

[0016] S5, prepare the casting residue, and transport the slag pot containing the casting residue to the desulfurization process via the transport line;

[0017] S6, prepare desulfurization slag, the molten iron desulfurization slag pot is waiting to remove desulfurization slag in the desulfurization slag process;

[0018] S7, hot iron desulfurization slag and mixed liquid casting residue are hot tempered in a hot pouring pool.

[0019] S8, after the reaction has been going on for a period of time, is processed according to the subsequent procedures for desulfurization slag.

[0020] Preferably, step S3 specifically includes:

[0021] The desulfurization slag tank is kept warm by baking or reheating, with the baking or reheating temperature set at 300℃~500℃.

[0022] Preferably, step S4 specifically includes:

[0023] Empty molten iron desulfurization slag ladles with lids and hot insulation are transported to the molten iron slag removal station to wait for slag collection. Then, the ladles are transported to the casting residue treatment plant. Metallurgical cranes are used to lift the covered hot molten iron desulfurization slag ladles to the molten iron desulfurization slag and casting residue mixing station.

[0024] Preferably, step S5 specifically includes:

[0025] Several empty casting slag containers are stored at the casting slag treatment site. The empty casting slag containers are transported by slag tank trucks to the continuous casting steel pouring process to wait for slag discharge. After the continuous casting process is completed, the steel ladle is lifted by a crane to the side of the slag container, and the casting slag in the steel ladle is poured into the slag container. Then the slag container containing the casting slag is transported from the designated route to the desulfurization process to wait for mixing and modification with the desulfurization slag.

[0026] Preferably, step S6 specifically includes:

[0027] Matching the desulfurization slag treatment cycle, the casting residue tank is carried by a slag tank truck. After being filled with high-temperature, incandescent liquid casting residue, it is quickly driven to the casting residue treatment site. A metallurgical crane is used to lift the casting residue tank and transport it to the position above the desulfurization slag tank.

[0028] Preferably, step S7 specifically includes:

[0029] Hot desulfurization slag and mixed liquid foundry residue are hot-conditioned in a hot pouring pool. The relatively large space of the hot pouring pool is used to change the agglomerated and difficult-to-handle characteristics of the hot desulfurization slag, turning it into an easily handled modified slag for subsequent treatment. The crane adjusts the relative position, distance and angle between the foundry residue pot and the desulfurization slag pot, and pours the liquid foundry residue into the hot desulfurization slag below. The two slags react for a period of time.

[0030] If the mixed slag still has enough heat and can be poured out after the two slags have been mixed and reacted for a period of time, then the mixed slag in the hot desulfurization slag tank can be poured back into the casting residue slag tank, i.e., secondary slag pouring.

[0031] After the desulfurization slag tank is emptied, it is returned to the baking station by a metallurgical crane or a tank-carrying vehicle for reheating, so that its temperature returns to the initial state of 300-500℃, and then it returns to the slag removal station to start the second cycle.

[0032] Preferably, step S8 specifically includes:

[0033] After one or two mixing processes, the desulfurization slag and casting residue of molten iron are transformed into casting residue-like slag. The slag-iron adhesion is eliminated, and the mixed slag is in a sintered and loose state, making it easier to separate the steel and slag. Subsequently, the mixed slag in the slag pot is processed according to the subsequent process of casting residue.

[0034] After modification, the mixed slag is either hot-pouring, added to a drum, or hot-quenched for subsequent treatment similar to casting residue, gradually achieving slag-iron separation. The obtained iron is returned to production for use, while the tailings are outsourced for treatment.

[0035] The present invention provides a method for conditioning and modifying hot desulfurization slag in steelmaking, which overcomes the shortcomings of existing technologies, avoids the formation of large slag-iron clumps, and is highly operable and can operate continuously. Addressing the problems of desulfurization slag easily forming large clumps, long processing flow, high cost, and significant pollution, the present invention also has the following advantages:

[0036] (1) By mixing and modifying hot desulfurization slag and liquid casting residue, the mixed slag is made into a sintered and loose state, making it easy to separate steel and slag, thus eliminating the generation of large slag lumps from the source.

[0037] (2) After the modification, the mixed slag is either hot-pouring, added to the drum, or hot-quenched for subsequent casting residue treatment to gradually achieve slag-iron separation. The iron obtained is returned to production for use, and the tail slag is outsourced for treatment.

[0038] (3) This patented technology avoids the cutting and processing of large slag lumps, reduces energy consumption, saves costs, and eliminates environmental pollution during the processing.

[0039] Therefore, this patented technology meets the needs of existing iron and steel metallurgical processes for the treatment of desulfurized slag from molten iron, and has the comprehensive effects of energy saving, carbon reduction, and clean and environmental protection. Detailed Implementation

[0040] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0041] This invention provides a method for conditioning and modifying hot desulfurization slag in steelmaking;

[0042] Hot desulfurization slag from molten iron and mixed with liquid foundry residue are hot-conditioned in a hot pouring tank. The relatively large space of the hot pouring tank helps to modify the agglomerated and difficult-to-handle characteristics of the desulfurization slag, transforming it into a more easily processed modified slag for subsequent treatment. Foundry residue has low oxidizing properties and a relatively lower temperature compared to converter slag, resulting in a less intense carbon-oxygen reaction and better operability, thus enabling its transformation into an easily processed modified slag for subsequent treatment.

[0043] The method for conditioning and modifying hot desulfurization slag in steelmaking according to the present invention specifically includes the following steps:

[0044] S1, set up a transportation line for returning the casting residue tank to the desulfurization process, and set up a separate line for returning the casting residue tank to the desulfurization process to facilitate the modification of the desulfurization slag with casting residue.

[0045] S2, fixed-point operation, sets up a mixing station for hot iron desulfurization slag and casting residue in the desulfurization process, which is used for hot tempering and modification of hot iron desulfurization slag.

[0046] S3, temperature control: A desulfurization slag pot baking station is set up in the desulfurization process. Induction heating or flame baking is used to bake or reheat the desulfurization slag pot of molten iron, maintain the hot state of the desulfurization slag pot, reduce the rapid cooling after the desulfurization slag falls in, make up for the heat loss during the operation of the desulfurization slag pot, and always maintain the hot state of the desulfurization slag pot. This provides a guarantee and support for the mixed slag in the desulfurization slag pot to be poured into the casting residue slag pot for a second mixing, so that the hot modification of the molten iron desulfurization slag is more complete.

[0047] S4, equipped with ladle-holding cars, is set up at the slag removal station of molten iron desulfurization slag to place and move empty or heavy ladle molten iron desulfurization slag ladles at designated stations and to transfer them between related stations.

[0048] S5. Prepare casting residue. Store several empty casting residue containers at the casting residue treatment site. The empty containers are transported by slag ladle cars to the continuous casting steel pouring process to await slag discharge. After the continuous casting process is completed, the ladle is lifted by a crane to the slag containers, and the casting residue in the ladle is poured into the slag containers. Then, the slag containers containing casting residue are transported from the designated route to the desulfurization process to await mixing and modification with the desulfurization slag.

[0049] S6, prepare desulfurization slag. The desulfurization slag pot of molten iron is waiting to remove the desulfurization slag in the desulfurization slag process. For each furnace of slag removed, the casting residue is modified once.

[0050] S7, mixed modification, is carried out in a hot pouring tank. The specific scheme is to hot temper the hot iron desulfurization slag and the mixed liquid casting residue in the hot pouring tank. The space of the hot pouring tank is relatively large, which changes the agglomerated and difficult-to-treat characteristics of the iron desulfurization slag and transforms it into a modified slag that is easy to treat for subsequent disposal.

[0051] S8, after reacting for a period of time, is processed according to the subsequent process of desulfurization slag; the empty desulfurization slag can is returned to the mixing station by a metallurgical crane, and the ladle car then returns the empty desulfurization slag can to the molten iron slag removal station. When the molten iron ladle is desulfurized and moved to the slag removal station, slag collection begins, thus starting the second cycle.

[0052] Example

[0053] This embodiment provides a method for conditioning and modifying hot desulfurization slag in steelmaking, specifically including:

[0054] A separate transport line is set up to return the casting residue tank to the desulfurization process.

[0055] A mixing station for molten iron desulfurization slag and residual slag is set up in the desulfurization process.

[0056] Prepare several empty desulfurization slag containers for molten iron and transport them to the desulfurization process.

[0057] The empty desulfurization slag cans are lifted to the baking station using a tank-carrying truck or a metallurgical crane in the casting residue treatment plant for baking. The baking temperature is set at 300-500℃.

[0058] Then, the covered hot-insulated molten iron desulfurization slag empty ladle is transported to the molten iron slag removal station by a ladle-carrying truck to await slag collection. Subsequently, the covered hot-insulated desulfurization slag heavy ladle is transported by the ladle-carrying truck to the foundry residue treatment site, where a metallurgical crane lifts the covered desulfurization slag heavy ladle to the molten iron desulfurization slag and foundry residue mixing station and places it there.

[0059] Matching the desulfurization slag treatment cycle, the slag tank is carried by a slag tank truck. After being filled with high-temperature, hot, liquid casting slag, it is quickly driven to the casting slag treatment site. A metallurgical crane is used to lift the slag tank and transport it above the desulfurization slag tank that was just placed.

[0060] The process is carried out in a hot pouring tank. Specifically, the hot desulfurization slag and the mixed liquid casting residue are hot-tempered in the hot pouring tank. The hot pouring tank has a relatively large space, which changes the agglomerated and difficult-to-handle characteristics of the hot desulfurization slag, turning it into a modified slag that is easier to handle for subsequent treatment. The crane adjusts the relative position, distance and angle between the residue tank and the desulfurization slag tank, and pours the liquid casting residue into the hot desulfurization slag below. The two slags react for a period of time.

[0061] If the mixed slag still has enough heat to be poured out after the two slags have been mixed and reacted for a period of time, then the mixed slag in the hot desulfurization slag tank can be poured back into the casting residue slag tank, which is called secondary slag pouring.

[0062] After the desulfurization slag tank is emptied, it is returned to the baking station by a metallurgical crane or a tank-carrying vehicle for reheating, so that its temperature returns to the initial state of 300-500℃, and then it returns to the slag removal station to start the second cycle.

[0063] After one or two mixing processes, the desulfurization slag and foundry residue of molten iron are transformed into a foundry residue-like slag. The slag-iron adhesion is eliminated, and the mixed slag is in a sintered and loose state, making it easier to separate the steel and slag. Subsequently, the mixed slag in the slag ladle is processed according to the subsequent processes for foundry residue. The modified mixed slag is then subjected to subsequent foundry residue-like treatment, either by hot pouring, adding to a drum, or hot quenching, to gradually achieve slag-iron separation. The obtained iron is returned to production for reuse, while the tailings are outsourced for processing (e.g., for external sale).

[0064] The emptied casting residue jar is then returned to the slag car by a metallurgical crane, and then to the casting residue receiving station to start its second cycle.

[0065] This leads to a new method for hot tempering and modification of desulfurized molten iron slag.

[0066] Here, the desulfurization slag tank cover is made of heat-resistant steel or ordinary carbon steel frame with refractory castable inside.

[0067] The capping (uncapping) machine can be mobile, moving along with the desulfurization slag tank; or it can be fixed, with one set installed at each workstation where capping (uncapping) is required.

[0068] The oil pipes and other components of the tanker truck are designed with comprehensive protection to prevent oil evaporation and avoid safety issues caused by high-temperature slag splashing.

[0069] The iron desulfurization slag removal station and the casting residue receiving station are both relatively close to the casting residue treatment site, with a distance of 100 to 200 meters.

[0070] The slag pot for desulfurization slag in molten iron contains about 20% to 30% of the volume of slag, while the volume of casting residue slag accounts for 40% to 80% of the volume of the slag pot for casting residue slag.

[0071] Desulfurization slag of molten iron: The weight ratio of casting residue slag is 1:5 to 1:2.

[0072] The temperature of the desulfurization residue is approximately 1200–1400℃.

[0073] The temperature of the casting residue is approximately 1400–1700℃, and the viscosity is below 0.1 Pa·s.

[0074] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for conditioning and modifying hot desulfurization slag in steelmaking, characterized in that: Hot desulfurization slag from molten iron and mixed liquid foundry residue are subjected to hot tempering in a hot pouring pool. The space of the hot pouring pool is used to change the agglomerated and difficult-to-handle characteristics of the molten iron desulfurization slag, transforming it into a modified slag that is easy to handle for subsequent disposal.

2. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 1, characterized in that, The method for conditioning and modifying hot desulfurization slag in steelmaking specifically includes the following steps: S1, set up a transport line for returning casting residue tanks to the desulfurization process; S2, a mixing station for molten iron desulfurization slag and casting residue is set up in the desulfurization process; S3, a desulfurization slag pot baking station is set up in the desulfurization process, and induction heating or flame baking is used to bake or reheat the molten iron desulfurization slag pot. S4, a ladle-carrying vehicle is configured at the desulfurization slag removal station of molten iron; S5, prepare the casting residue, and transport the slag pot containing the casting residue to the desulfurization process via the transport line; S6, prepare desulfurization slag, the molten iron desulfurization slag pot is waiting to remove desulfurization slag in the desulfurization slag process; S7, hot iron desulfurization slag and mixed liquid casting residue are hot tempered in a hot pouring pool. S8, after the reaction time has elapsed, proceed with the subsequent processes for the desulfurization slag.

3. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 2, characterized in that, Step S3 specifically includes: The thermal state of the desulfurization slag tank is maintained by baking or reheating, with the baking or reheating temperature set at 300℃~500℃.

4. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 2, characterized in that, Step S4 specifically includes: Empty molten iron desulfurization slag ladles with lids and hot insulation are transported to the molten iron slag removal station to wait for slag collection. Then, the ladles are transported to the casting residue treatment plant. Metallurgical cranes are used to lift the covered hot molten iron desulfurization slag ladles to the molten iron desulfurization slag and casting residue mixing station.

5. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 2, characterized in that, Step S5 specifically includes: Several empty casting slag containers are stored at the casting slag treatment site. The empty casting slag containers are transported by slag tank trucks to the continuous casting steel pouring process to wait for slag discharge. After the continuous casting process is completed, the steel ladle is lifted by a crane to the side of the slag container, and the casting slag in the steel ladle is poured into the slag container. Then the slag container containing the casting slag is transported from the designated route to the desulfurization process to wait for mixing and modification with the desulfurization slag.

6. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 2, characterized in that, Step S6 specifically includes: Matching the desulfurization slag treatment cycle, the casting residue tank is carried by a slag tank truck. After being filled with high-temperature, incandescent liquid casting residue, it is quickly driven to the casting residue treatment site. A metallurgical crane is used to lift the casting residue tank and transport it to the position above the desulfurization slag tank.

7. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 2, characterized in that, Step S7 specifically includes: Hot desulfurization slag and mixed liquid foundry residue are hot-conditioned in a hot pouring pool. The space of the hot pouring pool is used to change the agglomerated and difficult-to-handle characteristics of the hot desulfurization slag, turning it into an easily handled modified slag for subsequent treatment. The crane adjusts the relative position, distance and angle between the foundry residue pot and the desulfurization slag pot, and pours the liquid foundry residue into the hot desulfurization slag below. The two slags react for a period of time. If the mixed slag still has enough heat and can be poured out after the two slags have been mixed and reacted for a period of time, then the mixed slag in the hot desulfurization slag tank can be poured back into the casting residue slag tank, i.e., secondary slag pouring. After the desulfurization slag tank is emptied, it is returned to the baking station by a metallurgical crane or a tank-carrying vehicle for reheating, so that its temperature returns to the initial state of 300-500℃, and then it returns to the slag removal station to start the second cycle.

8. The method for conditioning and modifying hot desulfurization slag in steelmaking according to claim 2, characterized in that, Step S8 specifically includes: After one or two mixing processes, the desulfurization slag and casting residue of molten iron are transformed into casting residue-like slag. The slag-iron adhesion is eliminated, and the mixed slag is in a sintered and loose state, making it easier to separate the steel and slag. Subsequently, the mixed slag in the slag pot is processed according to the subsequent process of casting residue. After modification, the mixed slag is either hot-pouring, added to a drum, or hot-quenched for subsequent treatment similar to casting residue, gradually achieving slag-iron separation. The obtained iron is returned to production for use, while the tailings are outsourced for treatment.