A method for cascade utilization of refined slag

Abstract

The present invention particularly relates to a method for cascade utilization of refined slag, and belongs to the field of utilization of smelting solid waste. A method for cascade utilization of refined slag includes the following steps: leaving liquid refined slag in a refining ladle; tapping molten steel obtained by converter smelting into a refining ladle to form a slag surface, and performing first-level utilization on the refined slag; adding aluminum to the slag surface, refining and pouring to obtain primary treatment slag; placing the primary treatment slag in a KR desulfurization ladle and stirring, and then adding lime, slagging after KR desulfurization, obtaining secondary treatment slag, and performing second-level utilization on the refined slag; mixing the secondary treatment slag with concrete after water pumping, magnetic separation and grinding, and performing third-level utilization on the refined slag. It can effectively treat refined slag, and at the same time can reduce the consumption of smelting raw materials, reduce smelting energy consumption, and shorten the smelting cycle.

Description

Technical Field

[0001] The invention belongs to the field of smelting solid waste utilization, and in particular relates to a cascade utilization method of refined slag. Background Art

[0002] Refined slag refers to waste slag generated in the refining process, such as VD slag, LF slag, RH slag, etc., the discharge volume of which accounts for about 2-5% of the processed molten steel volume, and it has a high sulfur content and is easy to pulverize and hydrate. As the amount of slag discharged increases, not only does the storage and treatment area increase, but it also causes dust pollution or water environment pollution. In the prior art, there is no record of the preferred refined slag treatment method. Summary of the invention

[0003] The purpose of the present application is to provide a method for cascade utilization of refined slag to solve the technical problem that the prior art cannot effectively process refined slag.

[0004] The embodiment of the present invention provides a method for cascade utilization of refined slag, comprising the following steps:

[0005] leaving the liquid refined slag in the refining ladle;

[0006] The molten steel obtained by converter smelting is tapped into the refining ladle to form a slag surface, and the refined slag is used for the first level;

[0007] adding aluminum to the slag surface, refining and pouring to obtain primary treated slag;

[0008] The primary treatment slag is placed in a KR desulfurization iron ladle and stirred, and then lime is added, and the slag is skimmed after KR desulfurization to obtain secondary treatment slag, and the refined slag is used for the second level;

[0009] The secondary treatment slag is mixed with concrete after water pumping, magnetic separation and grinding, and the refined slag is used for the third level.

[0010] Optionally, the components of the refined slag include, by mass percentage:

[0011] Al2O3: 20-35%, CaO: 45-55%, TFe: ≤1.0%, S: 0.1-0.3%, SiO2: 5-10%, MgO: 3-6%.

[0012] Optionally, the aluminum is aluminum particles, the amount of aluminum added is 1-2 kg / t, and the particle size of the aluminum is 5-10 mm.

[0013] Optionally, the components of the primary treatment slag include, by mass percentage:

[0014] Al2O3: 25-40%, CaO: 45-55%, TFe: ≤1.0%, S: 0.3-0.6%, SiO2: 5-10%, MgO: 3-6%.

[0015] Optionally, the stirring time is 5-8 minutes.

[0016] Optionally, when the target sulfur content of the molten iron is ≤0.0025%, the amount of lime added is 2-4 kg / t, and stirring is continued for 5-8 minutes after addition; when the target sulfur content of the molten iron is >0.0025%, stirring is continued for 5-8 minutes.

[0017] Optionally, the water pumping volume is 0.5-0.8m 3 / t, the watering time is 5-8h.

[0018] Optionally, the mass of metal separated by magnetic separation is 5-10kg / t.

[0019] Optionally, the grinding is performed by ball milling, the grinding time is 20-30 minutes, and the end point of the grinding is: the specific surface area of ​​the secondary treatment slag is 450-550m 2 / kg.

[0020] Optionally, the mass percentage of the secondary treated slag and concrete is 10-40%.

[0021] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0022] The method for cascade utilization of refined slag provided by an embodiment of the present invention utilizes the characteristics of refined slag containing components such as calcium, aluminum and low-melting-point minerals, firstly applies its hot cycle to refining to assist the refining process, reduce the amount of raw materials used in molten steel refining, and at the same time, performs a primary treatment on the refined slag to obtain primary treated slag; then, the primary treated slag is applied to KR desulfurization to assist the KR desulfurization process, reduce the amount of raw materials used in KR desulfurization, and at the same time, performs a secondary treatment on the primary treated slag to obtain secondary treated slag; and in the above two processes, heat can be transferred through the refined slag and the primary treated slag respectively, thereby reducing energy consumption; finally, utilizing the characteristics of the refined slag being highly hydrated and easy to pulverize, the secondary treated slag is used for mixing with concrete after specific treatment, thereby reducing the amount of concrete while ensuring the concrete performance, thereby realizing the cascade full-quantity utilization of refined slag.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a flow chart of the method provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0027] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. If there is a conflict, the present specification takes precedence. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. For example, room temperature can refer to a temperature within the range of 10 to 35°C.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0029] The technical solution of the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0030] According to a typical embodiment of the present invention, a method for cascade utilization of refined slag is provided, comprising the following steps:

[0031] S1. Keep the liquid refined slag in the refining ladle.

[0032] S2. The molten steel obtained by converter smelting is tapped into the refining ladle to form a slag surface, and the refined slag is utilized at the first level.

[0033] S3, adding aluminum to the slag surface, refining and pouring to obtain primary treated slag.

[0034] S4, placing the primary treated slag in a KR desulfurization iron ladle and stirring it, and then adding lime, and slagging after KR desulfurization to obtain secondary treated slag, and performing second-level utilization on the refined slag.

[0035] S5. After watering, magnetic separation and grinding, the secondary treated slag is mixed with concrete to perform tertiary utilization of the refined slag.

[0036] The method for cascade utilization of refined slag provided by an embodiment of the present invention utilizes the characteristics that refined slag contains components such as calcium, aluminum, and low-melting-point minerals. First, through steps S1-S3, the refined slag is hot-circulated and applied to refining to assist the refining and reduce the amount of raw materials used in refining. At the same time, the refined slag is treated once to obtain primary treated slag; then, through step S4, the primary treated slag is applied to KR desulfurization to assist the KR desulfurization and reduce the amount of raw materials used in KR desulfurization. At the same time, the primary treated slag is secondary treated to obtain secondary treated slag; and in steps S1-S4, since both the refined slag and the primary treated slag carry heat, the heat of the two can be effectively utilized respectively through the use of the two, thereby reducing energy consumption in the process; finally, through step S5, utilizing the characteristics that the refined slag is highly hydrated and easy to pulverize, the secondary treated slag is used for mixing with concrete after specific treatment, thereby reducing the amount of concrete while ensuring the performance of the concrete, thereby realizing the cascade full-scale utilization of the refined slag.

[0037] Specifically, the role of the primary treatment slag in the KR desulfurization process is: utilizing the high CaO characteristics of the primary treatment slag to replace the small-grained lime of the KR desulfurization agent. In addition, the high Al2O3 content in the primary treatment slag is beneficial to the preferential generation of 3CaO·Al2O3 with a melting point of 1539°C in the desulfurization product, inhibiting the formation of 2CaO·SiO2 and promoting the desulfurization reaction.

[0038] As an optional embodiment, the components of the refined slag include, by mass percentage:

[0039] Al2O3: 20-35%, CaO: 45-55%, TFe: ≤1.0%, S: 0.1-0.3%, SiO2: 5-10%, MgO: 3-6%.

[0040] As an optional implementation manner, the aluminum is aluminum particles, the amount of aluminum added is 1-2 kg / t, and the particle size of the aluminum is 5-10 mm.

[0041] The reason for controlling the amount of aluminum added is to control deoxidation on the one hand and to control alloy cost on the other hand.

[0042] The reason for controlling the particle size of aluminum is that it is conducive to the melting of aluminum particles. Aluminum particles smaller than 5mm are easily sucked by the dust removal system, causing material loss. Particle sizes above 10mm have a low melting rate, which is not conducive to efficient melting.

[0043] As an optional embodiment, the components of the primary treatment slag include, by mass percentage:

[0044] Al2O3: 25-40%, CaO: 45-55%, TFe: ≤1.0%, S: 0.3-0.6%, SiO2: 5-10%, MgO: 3-6%.

[0045] As an optional implementation manner, the stirring time is 5-8 minutes.

[0046] The reason for controlling the stirring time of KR desulfurization is that the stirring time is controlled according to the kinetic process of the desulfurization reaction; if the time is too short, the desulfurization reaction is not complete; if the stirring time is too long, the temperature loss is large.

[0047] The reason why the stirring time can be significantly reduced by using the once-treated slag for KR desulfurization is that the once-treated slag has a low melting point and is easy to melt, thereby improving the reaction efficiency.

[0048] As an optional implementation, when the target sulfur content of the molten iron is ≤0.0025%, the amount of lime added is 2-4 kg / t, and stirring is continued for 5-8 minutes after addition; when the target sulfur content of the molten iron is >0.0025%, stirring is continued for 5-8 minutes.

[0049] The reason for the above control is that the target sulfur content is lower than 0.0025% for low-sulfur steel, which requires deep desulfurization and high CaO content, so it is necessary to add some desulfurizer.

[0050] As an optional implementation, the water pumping amount is 0.5-0.8m 3 / t, the watering time is 5-8h.

[0051] As an optional implementation manner, the mass of metal separated by magnetic separation is 5-10 kg / t.

[0052] As an optional implementation, the grinding is performed by ball milling, the grinding time is 20-30 minutes, and the end point of the grinding is: the specific surface area of ​​the secondary treatment slag is 450-550m 2 / kg.

[0053] The reason for controlling the grinding time is that as the grinding time increases, the specific surface area of ​​the slag increases, and the specific surface area of ​​the slag can be controlled by controlling the grinding time.

[0054] The reason for controlling the grinding end point is to control the specific surface area of ​​the slag. If the specific surface area is too low, the activity of the slag will be low; if the specific surface area is too high, the grinding cost will increase.

[0055] The reason for using specific surface area as the endpoint is that the surface area is correlated with the grinding time.

[0056] As an optional implementation manner, the mass percentage of the secondary treated slag and concrete is 10-40%.

[0057] The present application will be described in detail below with reference to embodiments, comparative examples and experimental data.

[0058] Example 1

[0059] A method for cascade utilization of refined slag, comprising the following steps:

[0060] S1. Leave 3 tons of liquid refined slag at the bottom of the 300 tons refining ladle, and transport the refining ladle to the steel tapping position.

[0061] The components of the refined slag include: Al2O3: 30%, CaO: 55%, TFe: 0.1%, S: 0.2%, SiO2: 5%, and MgO: 4%.

[0062] S2. The molten steel obtained from converter smelting is tapped into a refining ladle to form a slag surface, and the refining slag is used for the first level, and then the refining ladle is transported to the refining furnace.

[0063] S3. Add 500kg aluminum particles to the slag surface, heat it for 12 minutes, refine it and pour it to obtain the primary treated slag, which is then transported to the KR desulfurization position.

[0064] in:

[0065] The particle size of aluminum is 5-10mm;

[0066] The composition of the primary treated slag includes: Al2O3: 38%, CaO: 50%, TFe: 0.2%, S: 0.5%, SiO2: 4%, MgO: 3.5%.

[0067] S4, pour the primary treatment slag into the KR desulfurization ladle after slagging, lower the KR stirring paddle to stir for 6 minutes, raise the KR stirring paddle, KR desulfurization is completed, the target sulfur content of the molten iron is 0.0025%, meeting the requirement of target sulfur content of the molten iron <0.0025%. Then slagging, the refined slag is used in the second level, and 4.5t of secondary treatment slag is obtained and transported to the water-making hot stewing station.

[0068] S5. After watering, magnetic separation and grinding, the secondary treated slag is mixed with concrete as a resource product, and the refined slag is used for the third level. 20t of concrete can fully utilize the secondary treated slag.

[0069] in:

[0070] The water volume is 0.5m 3 / t, the watering time is 8h;

[0071] The grinding process is ball milling, the grinding time is 20 minutes, and the grinding end point is: the specific surface area of ​​the secondary treatment slag is 460m 2 / kg;

[0072] The mixing mass percentage of secondary treated slag and concrete is 20%.

[0073] Example 2

[0074] A method for cascade utilization of refined slag, comprising the following steps:

[0075] S1. Leave 3 tons of liquid refined slag at the bottom of the 300 tons refining ladle, and transport the refining ladle to the steel tapping position.

[0076] The components of the refined slag include: Al2O3: 30%, CaO: 55%, TFe: 0.1%, S: 0.2%, SiO2: 5%, and MgO: 4%.

[0077] S2. The molten steel obtained from converter smelting is tapped into a refining ladle to form a slag surface, and the refining slag is used for the first level, and then the refining ladle is transported to the refining furnace.

[0078] S3. Add 500kg aluminum particles to the slag surface, heat it for 12 minutes, refine it and pour it to obtain the primary treated slag, which is then transported to the KR desulfurization position.

[0079] in:

[0080] The particle size of aluminum is 5-10mm;

[0081] The composition of the primary treated slag includes: Al2O3: 38%, CaO: 50%, TFe: 0.2%, S: 0.5%, SiO2: 4%, MgO: 3.5%.

[0082] S4, pour the primary treatment slag into the KR desulfurization ladle after slagging, lower the KR stirring paddle to stir for 7 minutes, raise the KR stirring paddle, KR desulfurization is completed, the target sulfur content of the molten iron is 0.0025%, meeting the requirement of target sulfur content of the molten iron ≤ 0.0025%. Then slagging, the refined slag is used in the second level, and 5.1t of secondary treatment slag is obtained, which is transported to the water-making hot stewing station.

[0083] S5. After watering, magnetic separation and grinding, the secondary treated slag is mixed with concrete as a resource product, and the refined slag is used for the third level. 25.5t of concrete can fully utilize the secondary treated slag.

[0084] in:

[0085] Water pumping volume: 0.5m 3 / t, the watering time is 8h;

[0086] The grinding process is ball milling, the grinding time is 20 minutes, and the grinding end point is: the specific surface area of ​​the secondary treatment slag is 460m 2 / kg;

[0087] The mixing mass percentage of secondary treated slag and concrete is 20%.

[0088] Comparative Example

[0089] This comparative example adopts the traditional process to directly discharge the refined slag. Taking a 300-ton ladle refining furnace as an example, the conventional process of KR desulfurization, converter smelting, refining and pouring is adopted.

[0090] The refining process uses small-grain lime as a desulfurizer, with a consumption of 2 tons. 1 t of aluminum particles is added to the slag surface. The heating time is 20 minutes. After refining, the sulfur content of the molten steel is 0.0010%. The KR process uses conventional desulfurizer small-grain lime, with a consumption of 6 kg / t. The KR stirring paddle is lowered and stirred for 20 minutes. The KR stirring paddle is raised. The KR refining process is completed and the target sulfur content of the molten iron is 0.0030%. The refining process and the KR desulfurization process produce a total of 10.5 tons of slag.

[0091] Experimental example

[0092] The raw material consumption, slag production, refining heating time and KR desulfurization stirring time of Examples 1-2 and the comparative example were statistically analyzed, and the specific results are shown in the table below.

[0093]

[0094] As can be seen from the above table, compared with the comparative example, the smelting effect of Example 1-2 is the same, but the raw material consumption is significantly reduced, the amount of steel slag produced is significantly reduced, the refining heating time is significantly reduced, and the KR desulfurization stirring time is significantly reduced, which is better than the comparative example in all aspects. The technical solution of the present application realizes the effective utilization of refined slag, which not only eliminates the space occupied by its stacking, but also effectively reduces the amount of raw materials and electricity consumption in the smelting process, and shortens the duration of the smelting process, and has good application prospects and practical significance. It is calculated that this method can reduce the raw materials for refining by 10-20kg / t, reduce the raw materials for KR desulfurization by 4-6kg / t, reduce the raw material consumption cost by 1.5-3.0 yuan / t steel, and reduce the amount of waste slag generated by 14-26kg / t.

[0095] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0096] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0097] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for cascade utilization of refined slag, characterized in that: The steps include: leaving the liquid refined slag in the refining ladle; The molten steel obtained by converter smelting is tapped into the refining ladle to form a slag surface, and the refined slag is used for the first level; adding aluminum to the slag surface, refining and pouring to obtain primary treated slag; The primary treatment slag is placed in a KR desulfurization iron ladle and stirred, and then lime is added, and the slag is skimmed after KR desulfurization to obtain secondary treatment slag, and the refined slag is used for the second level; The secondary treatment slag is mixed with concrete after watering, magnetic separation and grinding, and the refined slag is used for the third level; In terms of mass percentage, the components of the refined slag include: Al2O3: 20-35%, CaO: 45-55%, TFe: ≤1.0%, S: 0.1-0.3%, SiO2: 5-10%, MgO: 3-6%; In terms of mass percentage, the components of the primary treatment slag include: Al2O3: 25-40%, CaO: 45-55%, TFe: ≤1.0%, S: 0.3-0.6%, SiO2: 5-10%, MgO: 3-6%.

2. The method for cascade utilization of refined slag according to claim 1, characterized in that: The aluminum is in the form of aluminum particles, the amount of the aluminum added is 1-2 kg / t, and the particle size of the aluminum is 5-10 mm.

3. The method for cascade utilization of refined slag according to claim 1, characterized in that: The stirring time is 5-8 min.

4. The method for cascade utilization of refined slag according to claim 3, characterized in that: When the target sulfur content of the molten iron is ≤0.0025%, the amount of lime added is 2-4 kg / t, and stirring is continued for 5-8 minutes after addition; when the target sulfur content of the molten iron is >0.0025%, stirring is continued for 5-8 minutes.

5. The method for cascade utilization of refined slag according to claim 1, characterized in that: The water pumping amount is 0.5-0.8m 3 / t, the watering time is 5-8h.

6. The method for cascade utilization of refined slag according to claim 1, characterized in that: The mass of metal separated by magnetic separation is 5-10kg / t.

7. The method for cascade utilization of refined slag according to claim 1, characterized in that: The grinding is performed by ball milling, the grinding time is 20-30 minutes, and the end point of the grinding is: the specific surface area of ​​the secondary treatment slag is 450-550m 2 / kg.

8. The method for cascade utilization of refined slag according to claim 1, characterized in that: The mixing mass percentage of the secondary treatment slag and concrete is 10-40%.

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