Comprehensive utilization method of molten iron desulfurization slag

Abstract

The invention discloses a comprehensive utilization method of molten iron desulfurization slag, and belongs to the technical field of effective utilization of waste resources. According to the method provided by the invention, the molten iron desulfurization slag is crushed into slag materials with different particle sizes, and then the slag materials with different particle sizes are subjected to the steps of magnetic separation, re-crushing, screening and re-magnetic separation to obtain an iron-containing material which can be directly used for ironmaking and re-sintering and a magnetic separation substance which can be used for a desulfurizing agent and a concrete admixture; according to the method, the molten iron desulfurization slag is recycled, the cost is saved, the environment is protected, and the method has excellent industrial prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of effective utilization of waste resources, and specifically relates to a comprehensive utilization method of molten iron desulfurization slag. Background Art

[0002] The molten iron smelted in the blast furnace cannot directly meet the index requirements of converter steelmaking, so a molten iron pretreatment process is required, which mainly adds slag-making agents to slag and desulfurize, thereby forming molten iron desulfurization slag. At present, molten iron desulfurization slag accounts for about 1.5-3.0% of the weight of molten iron.

[0003] At present, the conventional way to recycle hot metal desulfurization slag is to cool it to room temperature with water, and then screen out lumps and powders of different particle sizes. The lumps are directly fed into the converter or large smelting furnace, but because the lumps only enter the screening process and do not go through the magnetic separation and impurity removal process, the lumps still contain a certain amount of slag, which has a certain impact on subsequent use. Powdered materials are generally pressed into lumps for sintering. The fluctuation of the powdered material composition leads to certain fluctuations in the subsequent sintering indicators.

[0004] In the conventional water quenching and cooling post-treatment process, due to the participation of water, water reacts with active CaO and MgO in the hot metal desulfurization slag to produce Ca(OH)2 and Mg(OH)2. As a result, after the iron-containing materials are separated from the powdered materials by magnetic separation, the activity of the remaining magnetic separation residue is significantly reduced, and its 28-day activity is only 50-60%. Summary of the invention

[0005] In view of the above-mentioned prior art, the present invention provides a method for recycling molten iron desulfurization slag, which solves the problem of insufficient utilization of molten iron desulfurization slag.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a method for recycling molten iron desulfurization slag, comprising the following steps:

[0007] S1: Roll the hot molten iron desulfurization slag using a roller pressing device, and let the rolled molten iron desulfurization slag cool to room temperature;

[0008] S2: The cooled molten iron desulfurization slag is screened using a sieve to obtain materials with particle sizes of ≥80mm, 20-80mm and <20mm;

[0009] S3: Using magnetic separation equipment to magnetically separate the material with a particle size of ≥80 mm, and separating the iron-containing material 1 and the magnetic separation residue; the iron-containing material 1 is used for blast furnace ironmaking;

[0010] S4: After the magnetic separation residue is crushed by a crushing device, it is screened with a 20 mm × 20 mm screen to obtain an oversize material and an undersize material;

[0011] S5: Screening the material with a particle size of 20 to 80 mm by using steps S3 to S4 to obtain iron-containing material 2, oversize material 2 and undersize material 2; using the iron-containing material 2 for blast furnace ironmaking;

[0012] S6: The material with a particle size of less than 20 mm, the undersize material 1 and the undersize material 2 are mixed evenly and then rolled by a roller pressing device. After rolling, a 3 mm × 3 mm sieve is used for screening to obtain the oversize material 3 and the undersize material 3;

[0013] S7: Using magnetic separation equipment to magnetically separate the material 3 on the screen, and separating the iron-containing material 3 and the magnetic separation residue; returning the iron-containing material 3 for sintering, and using the magnetic separation residue as a concrete admixture;

[0014] S8: The undersize material 3 is subjected to magnetic separation by a magnetic separation device to separate the iron-containing material 4 and the magnetic separation residue, the iron-containing material 4 is returned for sintering, and the magnetic separation residue is used as a concrete admixture; or the undersize material 3 is used for molten iron desulfurization. Based on the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, the roller pressing equipment is a roller crusher.

[0016] Furthermore, the S2 sieve is a double-layer sieve of 20 mm×20 mm and 80 mm×80 mm.

[0017] Furthermore, the crushing equipment is a jaw crusher or a roll crusher.

[0018] Furthermore, the strength of the S3 and S7 magnetic separation equipment is 800-1000G, and the strength of the S8 magnetic separation equipment is 1800-2000G.

[0019] Furthermore, the specific surface area of ​​the magnetic separation residue used as concrete admixture in S7 and S8 is 500m 2 / kg.

[0020] The beneficial effects of the present invention are as follows: the hot metal desulfurization slag is dissociated through screening, crushing and magnetic separation processes, so that the metallic iron and slag are separated as much as possible, and the slag content in the metallic iron resource is reduced after separation, so that it can be better fed into the furnace. After the desulfurization slag is crushed, the iron-containing materials with a particle size of ≥80mm and 20-80mm can be directly used for blast furnace ironmaking, and the iron-containing materials with a particle size of 3-20mm and a particle size of ≤3mm can be returned for sintering; the 3mm undersize part can be recycled for desulfurization agent, and the 3mm undersize part can be further ground and used in concrete, thus realizing the comprehensive utilization of different types of materials in the hot metal desulfurization slag. At the same time, since the participation of water is avoided, the active ingredients in the powdered material, such as calcium oxide and magnesium oxide, are well retained, so that the activity of the material formed by grinding is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart. DETAILED DESCRIPTION

[0022] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0023] Example

[0024] A method for comprehensive utilization of molten iron desulfurization slag, the process flow of which is as follows: Figure 1 As shown, the following steps are included:

[0025] S1: Roll the hot molten iron desulfurization slag using a roller crusher, then spread the rolled molten iron desulfurization slag and allow it to cool naturally to room temperature;

[0026] S2: The cooled hot metal desulfurization slag is screened using a double-layer screen of 20mm×20mm and 80mm×80mm to obtain materials with three specifications of particle size ≥80mm, 20~80mm and <20mm;

[0027] S3: The materials with a particle size of ≥80mm are magnetically separated using a magnetic drum with a strength of 800G to separate the iron-containing materials and the magnetic separation residue;

[0028] S4: The magnetic separation residue of S3 is crushed by a jaw crusher, and then sieved with a 20 mm × 20 mm screen to obtain an oversize material and an undersize material;

[0029] S5: Screening the material with a particle size of 20 to 80 mm using steps S3 to S4 to obtain iron-containing material 2, oversize material 2, and undersize material 2;

[0030] S6: the material with a particle size of less than 20 mm, the undersize material 1 and the undersize material 2 are mixed evenly and rolled by a roller crusher. After rolling, a 3 mm × 3 mm sieve is used for screening to obtain the oversize material 3 and the undersize material 3;

[0031] S7: The material 3 on the screen is subjected to magnetic separation using a magnetic drum with a strength of 1000G to separate the iron-containing material 3 and the magnetic separation residue;

[0032] S8: One way to utilize the undersize material 3 is to use a magnetic drum with a strength of 1000G to perform magnetic separation on the undersize material 3 to separate the iron-containing material 4 and the magnetic separation residue;

[0033] S9: Grind the magnetic separation residues of S7 and S8 to a specific surface area of ​​500m 2 / kg, the activity after 28 days of testing reached 83.2%, and it can be directly used as concrete admixture;

[0034] S10: One way to utilize the undersize material 3 is to add a desulfurizer at a ratio of 12% and directly use it for molten iron desulfurization. When the amount of the desulfurizer is not increased, the desulfurization effect is not affected;

[0035] S11: The slag content of the iron-containing material 1 and the iron-containing material 2 is less than 3.0% after testing, and can be directly used in blast furnace ironmaking;

[0036] S12: Iron-containing material 3 and iron-containing material 4 can be sintered and used again;

[0037] According to statistics, iron-containing materials with a particle size of ≥80mm (4.7% of the materials) and 20-80mm (4.6% of the materials) are used for blast furnace ironmaking; iron-containing materials with a particle size of 3-20mm (11.8% of the materials) and iron-containing materials with a particle size of ≤3mm (15.4% of the materials) are used for sintering; the 3mm under-sieve magnetic separation residue accounts for 63.5%, which can be recycled as a desulfurizer or further ground to a specific surface area of ​​500m 2 / kg and then used as concrete admixture; in summary, the comprehensive utilization method of molten iron desulfurization slag provided by the present invention realizes the comprehensive utilization of different types of materials in the molten iron desulfurization slag.

[0038] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for comprehensive utilization of molten iron desulfurization slag, characterized in that: The following steps are involved: S1: Roll the hot molten iron desulfurization slag using a roller pressing device, and let the rolled molten iron desulfurization slag cool to room temperature; S2: The cooled molten iron desulfurization slag is screened using a sieve to obtain materials with particle sizes of ≥80mm, 20-80mm and <20mm; S3: Using magnetic separation equipment to magnetically separate the material with a particle size of ≥80 mm, and separating the iron-containing material 1 and the magnetic separation residue; the iron-containing material 1 is used for blast furnace ironmaking; S4: After the magnetic separation residue is crushed by a crushing device, it is screened with a 20 mm × 20 mm screen to obtain an oversize material and an undersize material; S5: Screening the material with a particle size of 20 to 80 mm by using steps S3 to S4 to obtain iron-containing material 2, oversize material 2 and undersize material 2; using the iron-containing material 2 for blast furnace ironmaking; S6: The material with a particle size of less than 20 mm, the undersize material 1 and the undersize material 2 are mixed evenly and then rolled by a roller pressing device. After rolling, a 3 mm × 3 mm sieve is used for screening to obtain the oversize material 3 and the undersize material 3; S7: Using magnetic separation equipment to magnetically separate the material 3 on the screen, and separating the iron-containing material 3 and the magnetic separation residue; returning the iron-containing material 3 for sintering, and using the magnetic separation residue as a concrete admixture; S8: Use magnetic separation equipment to magnetically separate the undersize material 3 to separate the iron-containing material 4 and the magnetic separation residue. The iron-containing material 4 is returned for sintering, and the magnetic separation residue is used as a concrete admixture; or the undersize material 3 is used for molten iron desulfurization.

2. The comprehensive utilization method of molten iron desulfurization slag according to claim 1, characterized in that: The roller pressing equipment is a roller crusher.

3. The comprehensive utilization method of molten iron desulfurization slag according to claim 1, characterized in that: The S2 screen is a double-layer screen of 20 mm×20 mm and 80 mm×80 mm.

4. The comprehensive utilization method of molten iron desulfurization slag according to claim 1, characterized in that: The crushing equipment is a jaw crusher or a roll crusher.

5. The comprehensive utilization method of molten iron desulfurization slag according to claim 1, characterized in that: The magnetic field strength of the magnetic separation in S3 and S7 is 800-1000G, and the magnetic field strength of the magnetic separation in S8 is 1800-2000G.

6. The comprehensive utilization method of molten iron desulfurization slag according to claim 1, characterized in that: The specific surface area of ​​the magnetic separation residue used for concrete admixture in S7 and S8 is 500m 2 / kg.

Images