Bulk-quantity utilization process of preheated steel slag and blast furnace pulverized coal synergistically injected steel slag

Abstract

The invention discloses a large-quantity utilization process of preheated steel slag and blast furnace pulverized coal for cooperative injection, and belongs to the field of resource utilization of steel slag. The steel slag tailing powder is preheated and injected into the blast furnace through the steel slag injection port, so that the problem of heat loss of the tuyere rotation area when the steel slag is melted and absorbs heat in the tuyere rotation area is solved, and the problem that the temperature of the hearth is reduced due to heat absorption of the steel slag is solved; the negative influence generated when the normal-temperature steel slag is sprayed into the blast furnace is eliminated; meanwhile, due to the yield advantage that a large amount of steel slag is utilized by a blast furnace, the process of the steel slag tailings from the steel-making furnace to the blast furnace can be directly achieved, the purpose that solid waste does not leave a factory is achieved, the treatment cost is reduced, the tailings can be melted by utilizing the temperature up to 2050-2300 DEG C in the convolution area, and CaO in the steel slag tailings increases the alkalinity of the slag, so that the slag can be recycled. Therefore, the acid slag environment of the nest area at the front end of the tuyere can be optimized, the air permeability of the area is improved, and coal gas can blow through the center.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel slag resource utilization, more particularly to a steel slag bulk utilization process of preheating steel slag and blast furnace coal powder. BACKGROUND

[0002] Steel slag is the main solid waste in the steelmaking process. There are about 100 million tons of steel slag in China that need to be further utilized every year. However, the resource utilization rate of steel slag in China is very low, which causes great waste of valuable resources contained in steel slag. In addition, the storage of a large amount of steel slag also occupies a large amount of land, causing soil and water pollution. Therefore, developing a large-scale, efficient and economic process for treating steel slag tailings is one of the major problems that steel enterprises must solve to achieve technological innovation and sustainable development.

[0003] The mineral composition of steel slag tailings is mainly silicate. Therefore, steel slag tailings are often used in the fields of cement admixture, paving material, engineering backfill, concrete products and glass ceramic, etc. However, the steel slag tailings have low cementitious activity and poor stability of free CaO and MgO, which can easily lead to expansion of the steel slag tailings, limiting their application in the field of building materials. On November 27, 2023, GB175-2023 “General Portland Cement” was officially released, and steel slag cannot be used as a mixed material for the production of general Portland cement, further limiting the effective utilization of steel slag resources.

[0004] At present, there are many deficiencies in the resource utilization of steel slag in China, including: the resource utilization rate of steel slag is very low, a large amount of steel slag occupies a large amount of land, and causes soil and water pollution; the addition of blast furnace flux from the top of the furnace and the increase of coal injection amount lead to the increase of binary basicity of the belly slag and the deterioration of fluidity, affecting the smooth operation of the furnace; the traditional flux addition method easily forms a low-permeability “bird nest” structure outside the tuyere rotation zone, causing the increase and fluctuation of air pressure, limiting the intensification of the blast furnace, and affecting the combustion efficiency of the injected coal powder in the rotation zone, etc. Therefore, how to realize the industrialized and effective utilization of steel slag tailings has become a problem that needs to be solved urgently.

[0005] The patent with publication number CN112226556A discloses a recycling method of converter steel slag or blast furnace steel slag, which is crushed to a particle size of 0.0002-0.5mm, then mixed with pulverized carbon-containing fuel powder in a mass ratio of 1-15:4-100, and then sprayed into the blast furnace from the carbon-containing fuel powder injection port for recycling. This method uses blast furnace and converter steel slag to improve the permeability of the blast furnace, reduces the amount of carbon-containing fuel required to maintain the permeability of the blast furnace, and reduces costs. However, this scheme has the following disadvantages: although the steel slag and coal powder are mixed and sprayed into the blast furnace, the physical heat absorption effect of the steel slag on the physical heat absorption zone of the blast furnace is not considered. In practice, a large amount of heat in the rotation zone will be absorbed by the steel slag after being sprayed into the tuyere with coal powder, resulting in a decrease in heat, and the blast furnace tuyere rotation zone is the key heat source of the blast furnace. The physical heat absorption of the steel slag in the rotation zone can easily cause a significant decrease in the temperature of the rotation zone and the hearth, and in severe cases, it can cause the hearth to cool down. At the same time, the steel slag itself may not be able to melt due to insufficient heat, thereby disturbing the phase balance in the furnace and increasing the operation risk. SUMMARY

[0006] 1. Technical problems to be solved by the present application In view of the insufficient utilization of steel tailings in the prior art, the present application provides a steel slag bulk utilization process for preheating steel slag and blast furnace coal powder, which realizes efficient utilization of steel tailings.

[0007] 2. Technical solutions To achieve the above-mentioned purposes, the technical solutions provided by the present application are as follows: The present application is a steel slag bulk utilization process for preheating steel slag and blast furnace coal powder. During the transportation of coal powder and steel slag, the steel slag is first preheated, and then the coal powder and the preheated steel slag are simultaneously sprayed into the tuyere of the blast furnace from different injection port positions, mixed with hot air, and then enter the tuyere rotation zone for melting and combustion reaction.

[0008] Further, the specific process is as follows: S1, sub-packaging and fluidization: the steel slag tailings powder and the coal powder are respectively sub-packaged in the injection tank and are respectively fluidized by the fluidization device; S2, steel slag preheating: the steel slag tailings are transported by hot air to achieve preheating of the steel slag tailings; S3, distribution: the coal powder is distributed to each coal powder injection port of the blast furnace tuyere by the coal powder distributor, and the steel slag tailings powder is distributed to the steel slag injection port of the blast furnace tuyere by the steel slag distributor; S4, combustion and melting: the coal powder and the preheated steel slag tailings powder are simultaneously injected into the blast furnace tuyere, mixed with hot air, and then enter the tuyere rotation zone for melting and combustion reaction.

[0009] Further, the coal powder in step S1 is transported to the coal powder bin through the coal powder pipeline and is distributed to the coal injection tank through the pipeline.

[0010] Further, the coal injection tank outlet is provided with a coal fluidization device, and the steel slag tank outlet is provided with a steel slag fluidization device.

[0011] Further, the outlet pipeline of the coal injection tank is provided with a coal outlet valve, and the outlet pipeline of the steel slag tank is provided with a steel slag powder valve.

[0012] Further, the outlet pipeline of the coal injection tank is connected in parallel with an N2 conveying pipe, and the coal powder is conveyed to the coal powder distributor by using N2.

[0013] Further, the outlet pipeline of the steel slag tank is connected in parallel with a hot air conveying pipe, and the steel slag tailing powder is conveyed to the steel slag distributor by using hot air, so as to preheat the steel slag tailing powder.

[0014] Further, the blast furnace tuyere is respectively provided with a coal powder injection port and a steel slag injection port, the coal powder distributor is connected with the coal powder injection port, and the steel slag distributor is connected with the steel slag injection port, so as to inject the coal powder and the steel slag tailing powder from different injection ports.

[0015] The blast furnace is a main equipment with the advantage of large capacity of processing steel tailing in the steel production process, and the temperature in the tuyere rotation area of the blast furnace is as high as 2050-2300 DEG C. In the present application, the coal powder and the preheated steel slag tailing are injected into the blast furnace together, the CaO content in the steel slag tailing accounts for about 40%, and the steel slag tailing can be used as a solvent of the blast furnace. Combined with the physical characteristics of the steel slag tailing and the production process of the blast furnace, the steel slag tailing and the coal powder are injected into the blast furnace together, and under the action of ultra-high temperature, the problem of CaO low-temperature dissociation can be solved by the reconstruction and regulation of the mineral phase of the blast furnace slag, and at the same time, the steel slag tailing is injected into the blast furnace from the tuyere as a solvent, which can increase the permeability of the blast furnace and improve the combustibility of the coal powder.

[0016] The injection process of the present application effectively solves the physical heat absorption effect of the steel slag tailing on the blast furnace tuyere rotation area after being injected. First, the steel slag tailing is preheated when being conveyed to the steel slag tailing distributor by hot air, and then is conveyed to the tuyere by hot air. The steel slag injection port is added at the hot air tuyere, so that the steel slag and the coal powder are injected into the blast furnace tuyere at the same time but through different injection ports, which not only solves the physical heat absorption effect of the blast furnace mixed injection of normal temperature steel slag on the blast furnace tuyere rotation area, but also makes the heated steel slag not affect the normal temperature coal powder, avoiding the premature volatilization of the coal powder.

[0017] 3. Beneficial effects Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects: (1) The steel slag bulk utilization process of preheating steel slag and blast furnace coal powder collaborative injection solves the heat consumption of the tuyere revolving zone after the steel slag tailings enter the blast furnace, realizes the bulk use of the steel slag tailings, improves the utilization rate of the steel slag, and reduces the accumulation and environmental pollution of the steel slag. At the same time, because the blast furnace has the advantage of bulk utilization of steel slag, the process from the steelmaking furnace to the blast furnace can be directly realized, the purpose of "solid waste not leaving the factory" is achieved, and the treatment cost is reduced.

[0018] (2) The steel slag bulk utilization process of preheating steel slag and blast furnace coal powder collaborative injection reduces the amount of belly slag, makes the slag basicity in the furnace change stably, improves the softening zone, expands the gas-liquid-solid phase coexistence zone in the furnace, increases the permeability of the blast furnace, and improves the combustion of the coal powder.

[0019] (3) The steel slag bulk utilization process of preheating steel slag and blast furnace coal powder collaborative injection, the steel slag tailings powder is preheated, enters the tuyere through the steel slag injection port, and is injected into the blast furnace. After mixing with hot air, it enters the tuyere revolving zone and undergoes melting and combustion reactions. The temperature in the revolving zone is as high as 2050-2300 DEG C, which can melt the tailings. Because the CaO in the steel slag tailings increases the slag basicity, the acidic slag environment of the bird nest zone at the front end of the tuyere can be optimized, the permeability of this area is improved, and the coal gas is blown into the center.

[0020] (4) The steel slag bulk utilization process of preheating steel slag and blast furnace coal powder collaborative injection, the steel slag tailings powder is preheated, and is injected into the blast furnace through the increased steel slag injection port. Because the final slag basicity of the blast furnace needs to be maintained between 1.0-1.25, the CaO in the steel slag tailings increases the slag basicity. In order to balance the slag basicity and reduce environmental pollution, the amount of acidic materials such as pellets and lump ore entering the furnace is increased. By increasing the amount of lump ore, the use of sintering ore, which has heavy environmental pollution, is reduced. The price of lump ore is lower than that of sintered ore and pellet ore, so the production cost is reduced while the injection effect of the blast furnace is improved, realizing the double improvement of energy saving and economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is suitable for the process of preheating steel slag tailings for blast furnace injection in the embodiment; Figure 2 The figure is the slag basicity diagram of different parts of the blast furnace before and after the injection of preheated steel slag tailings.

[0022] Fig. 1: 1-coal pipeline, 2-steel slag pipeline, 3-pulverized coal bin, 4-steel slag powder bin, 5-coal injection tank, 6-steel slag tank, 7-coal fluidization device, 8-steel slag fluidization device, 9-coal valve, 10-steel slag powder valve, 11-pulverized coal distributor, 12-steel slag distributor, 13-pulverized coal injection port, 14-steel slag injection port, 15-N2 delivery pipe, 16-hot air delivery pipe, 17-blast furnace. DETAILED DESCRIPTION

[0023] For a further understanding of the present application, reference will be made to the following description of embodiments thereof taken in conjunction with the accompanying drawings.

[0024] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0025] The present application will be further described below in conjunction with examples.

[0026] Embodiments - coal pipeline 1, - steel slag pipeline 2, - pulverized coal bin 3, - steel slag powder bin 4, - coal injection tank 5, - steel slag tank 6, - coal fluidization device 7, - steel slag fluidization device 8, - coal valve 9, - steel slag powder valve 10, - pulverized coal distributor 11, - steel slag distributor 12, - pulverized coal injection port 13, - steel slag injection port 14, - N2 delivery pipe 15, - hot air delivery pipe 16, - blast furnace 17 In combination Figures 1-2 As shown, the present embodiment provides a steel slag bulk utilization process for preheating steel slag and simultaneous injection of blast furnace pulverized coal, during the transportation of pulverized coal and steel slag, the steel slag is first preheated, then the pulverized coal and the preheated steel slag are simultaneously injected into the tuyere of the blast furnace 17 from different injection port positions, mixed with hot air and then enter the tuyere rotation zone, and then melt and burn in the tuyere rotation zone. The specific process is as follows: S1, dispensing and fluidization: the steel slag tailing powder and the pulverized coal are respectively dispensed in the injection tank and are respectively fluidized by the fluidization device; S2, steel slag preheating: the steel slag tailing is delivered by hot air to achieve preheating of the steel slag tailing; S3, distribution: the pulverized coal is distributed to each pulverized coal injection port 13 of the tuyere of the blast furnace 17 by the pulverized coal distributor 11, and the steel slag tailing powder is distributed to the steel slag injection port 14 of the tuyere of the blast furnace 17 by the steel slag distributor 12; S4, combustion and melting: simultaneously inject the coal powder and the preheated steel slag tailing powder into the blast furnace 17 tuyere, mix with the hot air, and then enter the tuyere revolving zone, where the melting and combustion reactions take place. At a temperature of up to 2050-2300°C in the revolving zone, the coal powder part will combust, providing a large amount of heat energy for heating the iron ore and flux in the blast furnace. Due to the physical properties of the steel slag tailing powder, the steel slag tailing powder cannot combust, but will absorb heat physically, and the heated steel slag will reduce the physical heat absorption effect after entering the blast furnace revolving zone. The steel slag tailing powder will be melted and undergo a melting reaction to assist the combustion of the coal powder. Because there is a large amount of CaO in the steel slag tailing powder, the steel slag tailing powder, after being melted, can increase the slag basicity, optimize the acidic slag environment in the bird's nest zone at the front end of the tuyere, improve the permeability in this area, and facilitate the blowing of the coal gas through the center, while also helping to slow down the overall change in basicity in the blast furnace. Therefore, the process of preheating the steel slag tailing powder for blast furnace injection not only opens up a new route for steel slag recycling and bulk treatment, but also ensures the smooth operation of the blast furnace, while optimizing the environment in the bird's nest zone at the front end of the tuyere and improving the permeability in the area.

[0027] More specifically, referring to FIG. 1, Figure 1 As shown in FIG. 1, in step S1, the coal powder is transported to the coal powder bin 3 through the coal conveying pipeline 1 and is distributed to the coal injection tank 5 through the pipeline. The steel slag tailing powder is transported to the steel slag powder bin 4 through the steel slag pipeline 2 and is distributed to the steel slag tank 6 through the pipeline. The coal fluidization device 7 is provided at the outlet of the coal injection tank 5, and the steel slag fluidization device 8 is provided at the outlet of the steel slag tank 6. The provision of the fluidization devices can make the steel slag tailing powder and the coal powder flow in a fluidized state during the blast furnace injection process, improve their fluidity, and facilitate the uniform injection of the steel slag tailing powder and the coal powder. In the fluidization process, the solid particles interact with the gas or liquid passing through them, thereby achieving a state similar to that of a fluid, which is conducive to process requirements such as particle flow, chemical reaction, and heat exchange, and can also prevent the problem of powder accumulation in the cone of the multi-cone, multi-pipeline injection tank.

[0028] In this embodiment, a coal outlet valve 9 is provided on the outlet pipeline of the coal injection tank 5 to control the on-off of the conveying, and a steel slag powder valve 10 is provided on the outlet pipeline of the steel slag tank 6 to control the on-off of the conveying. The outlet pipeline of the coal injection tank 5 is connected in parallel with an N2 conveying pipeline 15, which is used to convey the coal powder to the coal powder distributor 11. The outlet pipeline of the steel slag tank 6 is connected in parallel with a hot air conveying pipeline 16, which is used to convey the steel slag tailing powder to the steel slag distributor 12, thereby preheating the steel slag tailing powder. Correspondingly, the blast furnace 17 tuyere is provided with a coal powder injection port 13 and a steel slag injection port 14, respectively. The coal powder distributor 11 is connected to the coal powder injection port 13, and the steel slag distributor 12 is connected to the steel slag injection port 14, so that the coal powder and the steel slag tailing powder are injected from different injection ports.

[0029] In this embodiment, the steel slag tailing powder and the coal powder are both delivered to the corresponding distributors by pneumatic conveying mode, the distributors are correspondingly installed at the end of the injection system, the coal powder distributor 11 and the steel slag distributor 12 are correspondingly provided with a corresponding number of outlet channels, each channel can uniformly distribute the coal powder or the steel slag tailing powder. When the coal powder and the preheated steel slag tailing powder are delivered to the corresponding distributors by pneumatic conveying, the distributors can make each channel uniformly distribute according to the number of tuyeres of the blast furnace and the process requirements.

[0030] In this embodiment, the steel slag tailing powder is preheated and injected into the blast furnace 17 through the steel slag injection port 14, which solves the problem of heat loss in the tuyere rotation zone when the steel slag is melted and endothermic in the tuyere rotation zone, and solves the problem of temperature reduction of the hearth caused by the endothermic of the steel slag; the negative effects caused by the injection of normal temperature steel slag into the blast furnace are eliminated; at the same time, because the blast furnace 17 has the advantage of large-scale utilization of steel slag, the process of steel slag tailing from the steelmaking furnace to the blast furnace can be directly realized, the purpose of "waste not out of the factory" is achieved, the treatment cost is reduced, and the high temperature of up to 2050-2300℃ in the rotation zone can be used to melt the tailing, because the CaO in the steel slag tailing increases the basicity of the slag, the acidic slag environment of the bird nest area in front of the tuyere can be optimized, the air permeability of this area is improved, which is beneficial to the blow-through of the coal gas to the center.

[0031] The above description of the present application and its embodiments is illustrative and not restrictive, and is only one of the embodiments of the present application, and is not limited to this. Therefore, if a person skilled in the art is inspired by this, without departing from the purpose of the present application, similar structural modes and embodiments can be designed without creative design, which should belong to the protection scope of the present application.

Claims

1. A process for large-scale utilization of steel slag through co-injection of preheated steel slag and pulverized blast furnace coal, characterized in that: During the separate transportation of pulverized coal and steel slag, the steel slag is preheated first, and then the pulverized coal and the preheated steel slag are simultaneously injected into the tuyeres of the blast furnace (17) from different injection nozzles. After mixing with the hot air, they enter the tuyeres swirling zone and undergo melting and combustion reactions in the tuyeres swirling zone.

2. The process for large-scale utilization of steel slag by co-injection of preheated steel slag and pulverized blast furnace coal according to claim 1, characterized in that, The specific process is as follows: S1. Packaging and fluidization: Steel slag tailings powder and coal powder are separately packaged into injection tanks and fluidized by fluidization devices respectively. S2. Steel slag preheating: Steel slag tailings are conveyed and preheated by hot air. S3. Distribution: The pulverized coal is distributed to each pulverized coal injection port (13) of the tuyeres of the blast furnace (17) via the pulverized coal distributor (11), and the slag tail powder is distributed to the slag injection port (14) of the tuyeres of the blast furnace (17) via the slag distributor (12). S4. Combustion and melting: At the same time, pulverized coal and preheated steel slag tail powder are injected into the blast furnace (17) tuyeres. After mixing with hot air, they enter the tuyeres swirling zone and undergo melting and combustion reactions in the tuyeres swirling zone.

3. The process for large-scale utilization of steel slag by co-injection of preheated steel slag and pulverized blast furnace coal according to claim 2, characterized in that: In step S1, pulverized coal is transported to the pulverized coal silo (3) via the coal conveying pipeline (1) and distributed to the pulverized coal injection tank (5) via the pipeline; slag tailings powder is transported to the slag powder silo (4) via the slag pipeline (2) and distributed to the slag tank (6) via the pipeline.

4. The large-scale utilization process of preheated steel slag and pulverized blast furnace coal in synergistic injection according to claim 3, characterized in that: The outlet of the pulverized coal tank (5) is equipped with a coal fluidization device (7), and the outlet of the steel slag tank (6) is equipped with a steel slag fluidization device (8).

5. The process for large-scale utilization of steel slag by co-injection of preheated steel slag and pulverized blast furnace coal according to claim 3, characterized in that: A coal discharge valve (9) is installed on the outlet pipe of the pulverized coal tank (5), and a steel slag powder valve (10) is installed on the outlet pipe of the steel slag tank (6).

6. The process for large-scale utilization of steel slag by co-injection of preheated steel slag and pulverized blast furnace coal according to claim 3, characterized in that: An N2 conveying pipe (15) is connected in parallel to the outlet pipe of the pulverized coal tank (5) to transport pulverized coal to the pulverized coal distributor (11) using N2.

7. The large-scale utilization process of preheated steel slag and pulverized blast furnace coal co-injection according to claim 6, characterized in that: A hot air conveying pipe (16) is connected in parallel to the outlet pipe of the steel slag tank (6), and the hot air is used to convey the steel slag tail powder to the steel slag distributor (12) to preheat the steel slag tail powder.

8. The process for large-scale utilization of steel slag by co-injection of preheated steel slag and pulverized blast furnace coal according to claim 7, characterized in that: The tuyeres of the blast furnace (17) are respectively equipped with pulverized coal injection port (13) and steel slag injection port (14). The pulverized coal distributor (11) is connected to the pulverized coal injection port (13), and the steel slag distributor (12) is connected to the steel slag injection port (14), so that pulverized coal and steel slag tail powder are injected from different injection ports.

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