System for co-processing steel slag by using blast furnace slag iron tapping process

Abstract

The system comprises an outer sleeve and an inner sleeve, the inner sleeve is located in the outer sleeve, the outer sleeve is arranged to be used for guiding the steel slag to flow into a layered main iron runner section, and the inner sleeve is arranged to be used for guiding the steel slag to flow into the layered main iron runner section. And the inner-layer sleeve is arranged to be used for guiding high-pressure gas to be sprayed to the main iron runner section before steel slag is added into the main iron runner section. According to the system for co-processing the steel slag in the blast furnace slag iron discharging process, the added steel slag can enter the liquid slag iron more easily, the steel slag can make full contact with the liquid slag iron, heat of the liquid slag iron is effectively utilized, the heat transfer and mass transfer process between the steel slag and the liquid slag iron is improved, and the heat transfer efficiency is improved. Therefore, the reaction between the alkaline oxide and the acidic oxide is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of steel slag treatment, and in particular, the invention relates to a system for collaboratively treating steel slag by utilizing a blast furnace slag iron tapping process. Background Art

[0002] Steel slag is the main solid waste (referred to as solid waste) generated during the steelmaking production process of the steel industry, and its production volume accounts for 10%-15% of crude steel production. In 2023, my country's crude steel production will reach 1.019 billion tons, and the production of steel slag will exceed 100 million tons. At present, the cumulative amount of steel slag has reached 1 billion tons. Steel slag contains a large amount of valuable components such as calcium, magnesium, and iron, and is a valuable solid waste resource. However, due to the poor stability of steel slag, the current resource utilization rate of steel slag is less than 25%. The accumulation of a large amount of steel slag not only occupies a large amount of land, but also causes environmental pollution and waste of resources. As a typical metallurgical bulk solid waste, the efficient resource utilization of steel slag has always been an urgent need faced by the steel industry. After decades of development, the current steel slag treatment processes and technologies at home and abroad mainly include hot pouring, hot stewing, shallow pan method, water quenching, wind quenching and drum method, but these treatment methods can only partially eliminate the free calcium oxide in steel slag. At the same time, steel slag treated by the above process is mainly used in building materials, road construction, microcrystalline glass, agricultural fertilizers, etc. Among them, it is used in the field of building materials, especially the use of steel slag gelling properties to prepare silicate cement, which has become the mainstream way to achieve its large-scale resource utilization, and its utilization accounts for 30%-50% of the current total steel slag disposal. However, on June 1, 2024, "General Portland Cement" (GB175-2023) will be officially implemented, and steel slag will no longer be used as a mixed material for general Portland cement. Therefore, how to achieve large-scale resource utilization of steel slag has become a common problem that the steel industry urgently needs to solve.

[0003] The volume expansion caused by the hydration reaction of free calcium oxide (f-CaO) in steel slag is the main reason for its poor stability. Therefore, how to reduce the content of free calcium oxide in steel slag is a key issue in the resource utilization of steel slag. Studies have found that materials rich in acidic oxides such as silicon and aluminum can effectively capture free calcium oxide in steel slag and convert it into silicates or aluminosilicates with good stability. Blast furnace ironmaking is to reduce iron ore into liquid iron and molten slag at high temperature. The liquid slag carrying a large amount of sensible heat is separated due to different specific gravities when passing through the main iron ditch and slag ditch in front of the furnace. The separated liquid iron enters the steelmaking process, and the molten slag generally enters the slag water quenching system to obtain water slag, which contains more SiO2 and Al2O3. It is a typical silicate material that can be used for cement production (the current utilization rate is more than 80%), so it can be used as a digester to capture free calcium oxide in steel slag.

[0004] In the existing method of disposing steel slag using the ironmaking system, the location where the steel slag is added is located in the main iron ditch section 2-4m away from the blast furnace tapping port. In this area, the liquid slag is in a turbulent flow state, and there are problems such as high ambient temperature and poor operating environment, making it difficult to add steel slag.

[0005] To solve the above problem, the slag can be added into the main iron channel section where the liquid slag and iron are layered (i.e., the molten slag is in the upper layer and the liquid iron is in the lower layer), such as Figure 3 However, it will bring new problems. Due to the low density of steel slag, the added steel slag will float on the surface of liquid blast furnace slag and it is difficult to enter the liquid slag iron, thus affecting the heat and mass transfer process between steel slag and liquid slag iron, and the reaction process between basic oxides and acidic oxides.

[0006] It is desirable to provide an improved system for co-processing slag using the blast furnace slag tapping process, particularly with regard to how to make it easier for the added slag to enter the interior of the liquid slag. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a system for co-disposing slag using the blast furnace slag iron process, the purpose of which is to make the added slag easier to enter the liquid slag iron.

[0008] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a system for collaboratively disposing of slag in the process of blast furnace slag tapping, comprising an outer casing and an inner casing, the inner casing being located inside the outer casing, the outer casing being configured to guide the slag to flow into the layered main iron ditch section, and the inner casing being configured to guide high-pressure gas to spray toward the main iron ditch section before adding slag to the main iron ditch section.

[0009] The pressure of the high-pressure gas is 200-300 kPa.

[0010] The outer sleeve comprises an outer sleeve body, and a first lining layer is arranged on the inner wall of the outer sleeve body.

[0011] The inner sleeve comprises an inner sleeve body, a second inner lining layer is arranged on the outer wall of the inner sleeve body, and a channel for placing steel slag is formed between the first inner lining layer and the second inner lining layer.

[0012] The outer sleeve is a conical tube body, and the large diameter end of the outer sleeve is located above the small diameter end.

[0013] The angle between the top surface and the outer circumferential surface of the outer sleeve is 85-90°.

[0014] The inner sleeve is a conical tube body, and the large diameter end of the inner sleeve is located below the small diameter end.

[0015] The angle between the bottom surface and the outer circumferential surface of the inner sleeve is 82-86°.

[0016] The diameter d2 of the small diameter end of the outer sleeve is (0.8-1.0)b, where b is the width of the main iron groove below the slag input point.

[0017] The diameter of the large diameter end of the inner sleeve is d3 = (0.4-0.5) d2.

[0018] The present invention utilizes a system for co-disposing slag in the blast furnace slag tapping process, which can make the added slag enter the liquid slag more easily, so that the slag can fully contact with the liquid slag, effectively utilize the heat of the liquid slag, improve the heat and mass transfer process between the slag and the liquid slag, and thus promote the reaction of basic oxides and acidic oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] This specification includes the following drawings, which show the following contents:

[0020] Figure 1 It is a front view of the system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron tapping process of the present invention;

[0021] Figure 2 It is a top view of the system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron tapping process of the present invention;

[0022] Figure 3 It is a schematic diagram of the location where slag is added to the main iron ditch section;

[0023] Markings in the figure are: 1. outer casing; 2. inner casing; 3. main iron ditch section; 4. secondary iron ditch section; 5. slag liquid level; 6. blast furnace; 7. slag ditch section. DETAILED DESCRIPTION

[0024] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0025] It should be noted that, in the following embodiments, the “first” and “second” mentioned do not represent an absolute distinction in structure and / or function, nor do they represent a sequential order of execution, but are merely for the convenience of description.

[0026] like Figures 1 to 3As shown, the present invention provides a system for collaboratively disposing of slag in a blast furnace slag iron tapping process, comprising an outer casing 1 and an inner casing 2, wherein the inner casing 2 is located inside the outer casing 1, the outer casing 1 is configured to guide the slag (either cold or hot) to flow into a layered main iron ditch section, and the inner casing 2 is configured to guide high-pressure gas to spray toward the main iron ditch section before adding the slag to the main iron ditch section, and the high-pressure gas is continuously sprayed toward the main iron ditch section during the process of the slag flowing toward the main iron ditch section.

[0027] Specifically, if Figure 3 As shown, the main iron ditch section is used to bear the functions of slag separation and molten iron diversion during the blast furnace iron tapping process. The liquid slag discharged from the blast furnace enters from the inlet of the main iron ditch section, and the liquid slag flows through the turbulent flow area and the stable flow area in the main iron ditch section in sequence. The slag input point (i.e., the slag adding position) is set in the main iron ditch section where the liquid slag has been layered, that is, the slag input point is located in the stable flow area. The liquid slag in this area has been layered, and the liquid iron is located below the molten slag, and the molten slag floats above the liquid iron. Through the system for collaboratively disposing slag in the blast furnace slag tapping process of the present invention, high-pressure gas is first sprayed into the main iron ditch section to blow away the molten slag floating above the liquid iron and leak out the lower layer of liquid iron, and then the slag is added to the main iron ditch section at the slag input point, so that the slag can be fully in contact with the liquid iron, and the heat of the iron is effectively used, thereby promoting the reaction of alkaline oxides and acidic oxides.

[0028] like Figure 1 and Figure 2 As shown, the outer casing 1 and the inner casing 2 are coaxially arranged, the outer casing 1 is used for placing steel slag, and the inner casing 2 is used for spraying high-pressure gas, which is nitrogen or argon; the pressure of the high-pressure gas is 200-300kPa.

[0029] In the present invention, the purpose and beneficial effects of spraying high-pressure gas are as follows:

[0030] The location for adding slag is in the main iron channel section where the liquid slag iron has been layered (see Figure 3 ), due to the density problem, the added steel slag is difficult to enter the liquid slag, thus affecting the heat transfer process, mass transfer process, and reaction process of basic oxides and acidic oxides between the steel slag and the liquid slag. To solve this problem, the molten slag floating on the liquid iron must be blown away and the steel slag must be added after the liquid iron leaks out, so that it can fully contact with the liquid iron and effectively utilize the heat of the iron to promote the reaction of basic oxides and acidic oxides.

[0031] Therefore, the purpose of using high-pressure gas in the present invention is to ensure that the slag above the liquid iron can be blown away smoothly, wherein the pressure of the high-pressure gas can be set to 2-3 atmospheres, i.e. 200-300 kPa.

[0032] like Figure 1 and Figure 2 As shown, the outer sleeve 1 includes an outer sleeve body, and the inner wall of the outer sleeve body is provided with a first inner lining layer. The inner sleeve 2 includes an inner sleeve body, and the outer wall of the inner sleeve body is provided with a second inner lining layer, and a channel for placing steel slag is formed between the first inner lining layer and the second inner lining layer, and the first inner lining layer and the second inner lining layer are in contact with the steel slag, and the first inner lining layer and the second inner lining layer are made of wear-resistant refractory materials, which can improve the service life.

[0033] like Figure 1 and Figure 2 As shown, the outer sleeve 1 is a conical tube body, and the diameter of the outer sleeve 1 gradually decreases from the upper end to the lower end. The large diameter end of the outer sleeve 1 is located above the small diameter end, the large diameter end of the outer sleeve 1 has the largest diameter, and the lower diameter end of the outer sleeve 1 has the smallest diameter. The angle β between the top surface and the outer cylindrical surface of the outer sleeve 1 is 85-90°, and β can be 86°, 87°, 88° or 89°, and the outer cylindrical surface of the outer sleeve 1 is a conical surface.

[0034] like Figure 1 and Figure 2 As shown, the inner sleeve 2 is a conical tube body, the diameter of the inner sleeve 2 gradually increases from the upper end to the lower end, the large diameter end of the inner sleeve 2 is located below the small diameter end, the angle α between the bottom surface and the outer cylindrical surface of the inner sleeve 2 is 82-86°, and α can be 83°, 84° or 85°, and the outer cylindrical surface of the inner sleeve 2 is a conical surface. The small diameter end of the inner sleeve 2 is provided with an air inlet, and the large diameter end of the inner sleeve 2 is provided with an air outlet.

[0035] In the present invention, the purpose and beneficial effects of setting the angles α and β are as follows:

[0036] Since the cross-section of the inner sleeve 2 is circular, when the high-pressure gas is blown onto the surface of the molten blast furnace slag, a circle will be formed (the area surrounded by the circle is recorded as the gas injection area), and the slag added by the outer sleeve 1 will eventually form a circular ring area with a diameter larger than the gas injection area (the area where the circular ring is located is recorded as the slag input area). If α and β are both 90°, there is no intersection area between the gas injection area and the slag input area. The result is that the molten slag directly below the inner sleeve 2 can be blown away by the high-pressure gas, while the molten slag directly below the outer sleeve 1 cannot be blown away, and the added slag is still on the surface of the molten slag and cannot contact the liquid iron, thereby affecting the reaction of the alkaline oxide and the acidic oxide. Therefore, after setting α: 82-86° and β: 85-90°, an intersection area appears between the gas injection area and the slag input area, that is, a part of the area of ​​the gas injection area overlaps with the area of ​​the slag input area. In this way, the added slag can contact with the liquid iron, and the high-pressure gas can play a stirring role, thereby improving the contact effect between the slag and the liquid slag iron, improving the kinetic conditions of the reaction between the alkaline oxide and the acidic oxide, and being more conducive to the digestion of free calcium oxide in the slag.

[0037] The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process of the present invention is connected to the gas supply system, and the gas supply system provides high-pressure gas to the inner casing 2. The system operation process and key parameters are as follows:

[0038] The whole operation process of the system is controlled by computer. The specific steps are as follows: (1) When the liquid slag iron in the blast furnace reaches Figure 3 When the liquid slag iron is in the stratified stable flow area shown in the figure, open the high-pressure gas valve of the gas supply system, and the high-pressure gas flow rate in the inner casing 2 is 80-100L / min (based on the stable blowing of the slag layer and the leakage of the molten iron layer); (2) when the slag layer is stably blown away, open the slag addition valve, and the slag addition speed v in the outer casing 1 is set according to formula (1); (3) after the blast furnace slag iron discharge process is completed, close the slag addition valve and the high-pressure gas valve in turn.

[0039]

[0040] Wherein, δ is the speed coefficient, which is 1.20-1.40; k is the ratio of the weight of added slag to the weight of liquid slag produced in one blast furnace slag tapping process; μ is the slag ratio (i.e., the mass of molten slag produced in producing one ton of molten iron); Q represents the speed of blast furnace discharge of liquid slag, i.e., the weight of liquid slag discharged from the blast furnace per unit time, which can be calculated using formula (2).

[0041]

[0042] Wherein, d is the average diameter of the blast furnace iron mouth; g is the gravitational acceleration constant; h is the liquid level difference of the center line of the blast furnace iron mouth outlet; l is the depth of the blast furnace iron mouth; P is the pressure inside the blast furnace; λ is the friction coefficient of the blast furnace iron mouth wall; ρ is the average density of liquid slag iron.

[0043] like Figure 3 As shown, H is the vertical height between the system and the molten blast furnace slag level, that is, the vertical height between the outer casing 1 and the inner casing 2 and the molten blast furnace slag level in the main iron ditch section, H is 0..3-0.6m; a is the distance from the system where the liquid slag begins to flow stably in layers, a is 0-0.5m; b is the width of the main iron ditch below the slag input point, b is confirmed by the actual width of the slag ditch on site.

[0044] like Figure 1 and Figure 2 As shown, L is the vertical height of the system, that is, the vertical height of the outer casing 1 and the inner casing 2, L is 0.75-1.5m; d2 is the diameter of the small diameter end of the outer casing 1, d2 = (0.8-1.0)b; d3 is the diameter of the large diameter end of the inner casing, d3 = (0.4-0.5)d2.

[0045] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A system for coordinating the treatment of steel slag using the blast furnace slag iron process, characterized in that: It includes an outer casing and an inner casing, the inner casing is located inside the outer casing, the outer casing is configured to guide the slag to flow into the layered main iron ditch section, and the inner casing is configured to guide the high-pressure gas to spray toward the main iron ditch section before adding the slag to the main iron ditch section.

2. The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process according to claim 1, characterized in that: The pressure of the high-pressure gas is 200-300 kPa.

3. The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process according to claim 1, characterized in that: The outer sleeve comprises an outer sleeve body, and a first lining layer is arranged on the inner wall of the outer sleeve body.

4. The system for coordinating the treatment of slag by utilizing the blast furnace slag iron process according to claim 1, characterized in that: The inner sleeve comprises an inner sleeve body, a second inner lining layer is arranged on the outer wall of the inner sleeve body, and a channel for placing steel slag is formed between the first inner lining layer and the second inner lining layer.

5. The system for co-disposing slag by utilizing the blast furnace slag iron process according to any one of claims 1 to 4, characterized in that: The outer sleeve is a conical tube body, and the large diameter end of the outer sleeve is located above the small diameter end.

6. The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process according to claim 5, characterized in that: The angle between the top surface and the outer circumferential surface of the outer sleeve is 85-90°.

7. The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process according to claim 5, characterized in that: The inner sleeve is a conical tube body, and the large diameter end of the inner sleeve is located below the small diameter end.

8. The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process according to claim 7, characterized in that: The angle between the bottom surface and the outer circumferential surface of the inner sleeve is 82-86°.

9. The system for co-disposing slag by utilizing the blast furnace slag iron process according to any one of claims 5 to 8, characterized in that: The diameter d2 of the small diameter end of the outer sleeve is (0.8-1.0)b, where b is the width of the main iron groove below the slag input point.

10. The system for coordinating the treatment of steel slag by utilizing the blast furnace slag iron process according to claim 9, characterized in that: The diameter of the large diameter end of the inner sleeve is d3 = (0.4-0.5) d2.

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