Production method for sintering ingredients by using red mud

Abstract

The invention discloses a production method for sintering ingredients by using red mud. The production method comprises the following steps: S1, pretreating the red mud: airing the red mud until the moisture content is 15-20%; s2, preparing an inner core: mixing the red mud treated in the S1 with first pulverized coal according to a mass ratio of 2: 1, wherein the granularity of the first pulverized coal is less than 1mm; s3, performing primary granulation: performing granulation on the mixture obtained in the S2 to form core pellets with the granularity not greater than 3mm; s4, intermediate layer formation: mixing the core pellets obtained in S3 with an iron-containing raw material, and carrying out secondary granulation to form an intermediate layer wrapping structure with the particle size not greater than 4mm; and S5, shell formation: mixing the material obtained in the step S4 with second pulverized coal, and carrying out third granulation to form three-layer-structure small balls with the granularity not greater than 5mm. Compared with the prior art, the invention has the advantages that the production method of the red mud for sintering ingredients is high in red mud utilization rate and ensures the quality of sintered ore.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization of red mud, specifically to a production method for using red mud as a sintering ingredient. Background Technology

[0002] Red mud is a highly alkaline solid waste generated during the production of alumina. Approximately 1.0-1.8 tons of red mud are generated for every ton of alumina produced.

[0003] Currently, the global stockpile of red mud has reached billions of tons, and is increasing by hundreds of millions of tons every year. The large-scale stockpiling of red mud not only occupies land resources, but its high alkalinity may also pollute the surrounding environment.

[0004] Sintering is an important process in steel production. Its main purpose is to sinter powdered iron-containing raw materials into lumpy sintered ore at high temperatures, providing raw materials for blast furnace ironmaking.

[0005] Traditional sintering materials mainly include iron-containing raw materials, flux, and fuel.

[0006] Existing technologies have included research on using red mud in sintering batches, but most of these methods treat red mud as a common raw material and mix it directly with other materials, which presents the following problems:

[0007] Red mud has a high water content and high viscosity, which can easily lead to uneven mixing.

[0008] The distribution of alkali metals in red mud is uncontrollable during sintering, which affects the quality of sintered ore.

[0009] The fluxing properties of red mud were not fully utilized;

[0010] The amount of red mud added is limited, resulting in a low resource utilization rate.

[0011] Therefore, it is of great significance to develop a sintering batching method that can fully utilize the characteristics of red mud and improve its utilization rate. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a production method for using red mud as a sintering ingredient with high red mud utilization rate and guaranteed sinter quality.

[0013] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a method for producing red mud as a sintering ingredient, comprising the following steps:

[0014] S1: Red mud pretreatment: Dry the red mud until the moisture content is 15-20%;

[0015] S2: Core preparation: The red mud treated in S1 is mixed with the first coal powder at a mass ratio of 2:1, and the particle size of the first coal powder is less than 1 mm;

[0016] S3: One-time granulation: Granulate the mixture obtained in S2 to form core microspheres with a particle size of no more than 3 mm;

[0017] S4: Intermediate layer formation: The core microspheres obtained in S3 are mixed with iron-containing raw materials and granulated a second time to form an intermediate layer encapsulation structure with a particle size of no more than 4 mm.

[0018] S5: Shell formation: The material obtained in S4 is mixed with the second coal powder and granulated for the third time to form three-layer structured spheres with a particle size of no more than 5 mm;

[0019] S6: Sintering material preparation: Add the three-layer structured microspheres obtained in S5 to the sintering material at 3-7% of the total dry material amount for sintering, and carry out the sintering operation.

[0020] Preferably, the particle size of the second coal powder in S5 is less than 0.8 mm.

[0021] Preferably, the iron-containing raw material S4 includes one or more of iron ore powder, steel rolling mill iron oxide scale, and blast furnace dust.

[0022] Preferably, the amount of the three-layer structured microspheres added in S6 is 4-6% of the total dry weight of the sintered material.

[0023] Preferably, the sintering material in S6 further includes a flux, which includes one or more of limestone, quicklime, and dolomite.

[0024] Preferably, the binary basicity of the sintering material is 1.8-2.2.

[0025] Preferably, the ignition temperature of the sintering process in S6 is 1000-1100℃, and the sintering negative pressure is 8-15kPa.

[0026] Another aspect of the present invention discloses a three-layer structured microsphere prepared by the above method.

[0027] Another aspect of the present invention discloses the application of three-layer structured microspheres in iron ore sintering.

[0028] The advantages of this invention compared with the prior art are: this invention encapsulates red mud in structurally stable spheres, which effectively improves its dispersibility in sintering batches and enhances the overall granulation effect of the mixture.

[0029] The design and process optimization of the three-layer structure spheres effectively solved the technical bottleneck of using red mud as a sintering ingredient, and achieved multiple goals such as high utilization rate of red mud, stable quality of sintered ore, and high production efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a process for using red mud as a raw material in sintering production. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] A method for producing red mud as a sintering ingredient includes the following steps:

[0033] (1) Red mud pretreatment: Dry the red mud until the moisture content is 15-20%;

[0034] (2) Core preparation: The treated red mud and the first coal powder are mixed at a mass ratio of 2:1;

[0035] (3) One-time granulation: The mixture is granulated to form core microspheres with a particle size ≤3mm;

[0036] (4) Intermediate layer formation: Mix the core microspheres with iron-containing raw materials and granulate them to form an intermediate layer with a particle size ≤4mm;

[0037] (5) Shell formation: The material is mixed with the second coal powder and granulated to form three-layer structured spheres with a particle size ≤5mm;

[0038] (6) Sintering materials: Add the three-layer structured small balls to the sintering material at a ratio of 3-7% for sintering.

[0039] Example 1

[0040] Red mud from an alumina plant was taken, and its main chemical components were: TFe 28.5%, SiO2 13.2%, Al2O3 18.6%, CaO 15.8%, and Na2O 6.5%.

[0041] The red mud was dried until its moisture content reached 18%.

[0042] Take 200 kg of dried red mud and mix it with 100 kg of coal powder with a particle size of <1 mm;

[0043] The mixture is granulated in a disc pelletizer to obtain core microspheres with a particle size of 2-3 mm;

[0044] Mix the core microspheres with 600 kg of iron ore powder and granulate to obtain an intermediate layer with a particle size of 3-4 mm;

[0045] Add 50 kg of coal powder with a particle size <0.8 mm and granulate to obtain three-layer structured spheres with a particle size of 4-5 mm;

[0046] Three-layer structured small balls were added to the sintering material at 5% of the total dry material weight, and ignited at 1050℃ and sintered under a negative pressure of 12kPa.

[0047] Results: Compared with the direct addition of red mud, the method of the present invention increases the sintering speed by 10%, reduces solid fuel consumption by 4.2 kg / t, and increases the strength of the sinter drum by 1.5%.

[0048] Example 2

[0049] The addition ratio of the three-layer structured microspheres was adjusted to 4% and 6%, and the process of Example 1 was repeated.

[0050] Results: Within the addition range of 4-6%, the sintering process was stable, the quality of the sintered ore was excellent, and all indicators were superior to the control group that directly added red mud.

[0051] The above embodiments demonstrate that the method of the present invention can effectively utilize red mud and improve sintering performance within an addition range of 3-7%.

[0052] Example 3

[0053] The particle size of the second coal powder was adjusted to <0.5mm, and other conditions were the same as in Example 1.

[0054] Results: After the coal powder in the outer shell is refined, the three-layer structure of the spheres is formed better, the combustion is more complete during sintering, and the fuel efficiency is further improved.

[0055] In this invention, unless otherwise expressly specified and limited, the first feature "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0056] Furthermore, "above," "over," and "on top" of the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" of the first feature and the second feature include the first feature being directly below or diagonally below the second feature, or simply indicating that the first feature is at a lower horizontal level than the second feature.

[0057] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for the production of a sintering burden from red mud, characterised in that, The method comprises the following steps: S1: Red mud pretreatment: The red mud is dried to a moisture content of 15-20%; S2: Core preparation: The treated red mud in S1 is mixed with first coal powder at a mass ratio of 2:1, and the first coal powder has a particle size of less than 1 mm; S3: First granulation: The mixture obtained in S2 is granulated to form core pellets with a particle size of not greater than 3 mm; S4: Intermediate layer formation: The core pellets obtained in S3 are mixed with iron-containing raw materials and subjected to second granulation to form an intermediate layer wrapped structure with a particle size of not greater than 4 mm; S5: Shell formation: The material obtained in S4 is mixed with second coal powder and subjected to third granulation to form three-layer structure pellets with a particle size of not greater than 5 mm; S6: Sintering batching: The three-layer structure pellets obtained in S5 are added to the sintering material at 3-7% of the total dry sintering material, and sintering operation is performed.

2. A method for the production of sintered burden ingredients from red mud according to claim 1, characterized in that: The particle size of the second coal powder in S5 is less than 0.8 mm.

3. A method for the production of sintered burden ingredients from red mud according to claim 1, characterized by: The iron-containing raw material in S4 includes one or more of iron ore powder, steel mill oxide scale, and blast furnace dust removal ash.

4. A method for the production of sintered burdening using red mud according to claim 1, characterized in that: The addition amount of the three-layer structure pellets in S6 is 4-6% of the total dry sintering material.

5. A method for the production of sintered burden ingredients from red mud according to claim 1, characterized by: The sintering material in S6 further includes a flux, and the flux includes one or more of limestone, quicklime, and dolomite.

6. A method for the production of sintered burden ingredients from red mud according to claim 5, characterized by: The binary basicity of the sintering material is 1.8-2.

2.

7. A method for the production of sintered burden ingredients from red mud according to claim 1, characterized by: The ignition temperature of the sintering process in S6 is 1000-1100°C, and the sintering negative pressure is 8-15 kPa.

8. A three-layer structure pellet prepared by the method of any one of claims 1-7.

9. Use of the three-layer structure pellet of claim 9 in iron ore sintering.

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