Blending and ore blending method for feeding dolomite powder into blending ore heap

Abstract

The invention relates to the technical field of ferrous metallurgy, in particular to an ore blending method for feeding dolomite powder into a blending ore heap, which comprises the following steps: (1) providing ore powder for blending and heap building: the ore powder for blending and heap building comprises at least three kinds of iron ore powder; (2) iron ore powder with the particle size larger than or equal to 3 mm, the proportion larger than or equal to 30 wt%, the balling index larger than or equal to 0.35 and the burning loss larger than or equal to 6 wt% is screened out, and when two kinds of iron ore powder are screened out, the iron ore powder is marked as iron ore powder I and iron ore powder II; when the number of the screened iron ore powder is larger than two, two kinds of iron ore powder with the maximum content in the evenly-mixed material obtained after evenly mixing and piling are selected from the screened iron ore powder and marked as iron ore powder I and iron ore powder II respectively; and (3) the iron ore powder I, the dolomite powder and the iron ore powder II are sequentially discharged to a batching belt according to the discharging sequence, and then the iron ore powder I, the dolomite powder and the iron ore powder II are evenly mixed with the homogenized material and the remaining iron ore powder to build a pile. According to the method, the dolomite powder is blended into the uniformly-mixed ore heap, the feeding pressure of a flux crushing system is reduced, and the quality of sintered ore is stabilized.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a method for mixing dolomite powder into a mixing ore pile. Background Art

[0002] Dolomite can be used as a source of CaO and MgO gangue during the sintering process, especially to provide MgO. Appropriately increasing the MgO content in blast furnace slag can improve the fluidity and desulfurization capacity of the slag. In order to ensure the MgO content in the slag, the current production process mostly adopts the process of adding dolomite to the sintering material. This process can ensure the MgO content in the blast furnace slag and inhibit the low-temperature reduction and pulverization of the sintered ore. Steel companies generally use purchased dolomite blocks, low-magnesium dolomite or dolomite and limestone intergrowth ores as sintering fluxes containing magnesium oxide for sintering production.

[0003] The large-scale development of modern sintering machines has brought great pressure to the flux crushing system. After the transformation of some steel enterprises, the flux crushing system cannot meet the requirements of crushing limestone and dolomite at the same time. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the flux crushing system of the existing sintering machine cannot meet the requirement of crushing limestone and dolomite at the same time after the large-scale sintering machine is provided, and a method for mixing dolomite powder into a mixed ore pile is provided. The method mixes dolomite powder into the mixed ore pile, can ensure the demand of sintering production, stabilize the quality of sintered ore, and reduce the cost of sintered ore.

[0005] In order to achieve the above object, the present invention provides a method for mixing dolomite powder into a mixed ore pile, the method comprising the following steps:

[0006] (1) Providing ore powder for mixing and building a pile: the ore powder for mixing and building a pile comprises at least three kinds of iron ore powder;

[0007] (2) Screening of ore powder: particle size analysis, ball formation index and burnout test are performed on each type of iron ore powder, and iron ore powder with a particle size of ≥3 mm, a proportion of ≥30 wt%, a ball formation index of ≥0.35 and a burnout of ≥6 wt% is screened out. When there are two types of iron ore powder screened out, they are recorded as iron ore powder I and iron ore powder II respectively; when there are more than two types of iron ore powder screened out, the two types of iron ore powder with the largest content in the mixed material obtained after mixing and building a pile are selected from them, and they are recorded as iron ore powder I and iron ore powder II respectively;

[0008] (3) Mixing and piling: The iron ore powder I, dolomite powder, and iron ore powder II are fed to the batching belt in the order of feeding, and then mixed with the homogenized material and the remaining iron ore powder to form a pile to obtain a mixed material.

[0009] In conventional mixing and heaping operations in the art, a variety of iron ore powders from different sources and different manufacturers are usually used for mixing and heaping. In step (1), the at least three kinds of iron ore powders mentioned in the present invention refer to at least three kinds of iron ore powders from different sources and different manufacturers, and each of these iron ore powders has different specific component content, particle size, spheroidization index and burning loss.

[0010] In a preferred case, the content of limonite in the ore powder for mixing and building a pile is ≥40wt%, that is, the content of limonite in the ore powder for mixing and building a pile is ≥40wt%, and further, the content of Fe2O3·nH2O in the limonite accounts for 50wt% or more of the iron oxide content.

[0011] Among them, since the specific component content of each iron ore powder is different, their respective performances are also different. In actual operation, due to the different actual sintering production requirements of the mixed material obtained by mixing and piling, the performance and specific composition of the mixed material will also be different, and the number and specific content ratio of the required iron ore powder will also be different. Therefore, the specific number and specific content ratio of the iron ore powder used in the present invention only need to satisfy the physical and chemical properties of the final mixed material to meet the technical indicators.

[0012] In step (2) of the present invention, after each type of iron ore powder is screened according to the requirements, the iron ore powders that meet the requirements (particle size ≥3mm accounts for ≥30wt%, spheroidization index ≥0.35 and burnout ≥6wt%) are usually greater than or equal to two types. When only two types of iron ore powders that meet the requirements are screened out, the two types of iron ore powders that meet the requirements can be directly recorded as iron ore powder I and iron ore powder II, respectively; when more than two types of iron ore powders that meet the requirements are screened out, the contents (weight contents) of these types of iron ore powders that meet the requirements in the mixed material are further compared (the content of each type of iron ore powder used in the mixed material will be confirmed in advance), and then the two types with the largest content in the mixed material are further selected from these types of iron ore powders that meet the requirements, and are recorded as iron ore powder I and iron ore powder II, respectively.

[0013] In the present invention, the iron ore powder I and iron ore powder II selected by the above method have a larger portion with a particle size ≥ 3 mm and good hydrophilicity and ball-forming performance. They can play the role of nuclear particles in the process of mixing and piling with dolomite powder with finer particle size, and are convenient for balling with dolomite powder.

[0014] There is no special requirement as to which iron ore powder is recorded as iron ore powder I and which is recorded as iron ore powder II. One of the iron ore powders can be recorded as iron ore powder I and the other as iron ore powder II.

[0015] For example, in a specific embodiment, iron ore powders from five different sources are used to mix and build a pile, namely iron ore powder A, iron ore powder B, iron ore powder C, iron ore powder D and iron ore powder E. Each iron ore powder is subjected to particle size analysis, ball formation index and burnout test. If the screened iron ore powders with a particle size ≥3 mm account for ≥30wt%, a ball formation index ≥0.35 and a burnout ≥6wt% are only iron ore powder A and iron ore powder B, then iron ore powder A and iron ore powder B are recorded as iron ore powder I and iron ore powder II; if the screened iron ore powders with a particle size ≥3 mm account for ≥30wt%, a ball formation index ≥0.35 and a burnout ≥6wt%, then iron ore powder A and iron ore powder B are recorded as iron ore powder I and iron ore powder II; .35 and if the iron ore powders with burnout ≥6wt% include iron ore powder A, iron ore powder B, iron ore powder C and iron ore powder D, then further compare the contents of iron ore powder A, iron ore powder B, iron ore powder C and iron ore powder D in the mixed material obtained after mixing and pile building. After comparison, if the contents of iron ore powder A and iron ore powder B are the largest among iron ore powder A, iron ore powder B, iron ore powder C and iron ore powder D, then iron ore powder A and iron ore powder B are recorded as iron ore powder I and iron ore powder II; among them, iron ore powder A can be recorded as iron ore powder I and iron ore powder B as iron ore powder II, or iron ore powder A can be recorded as iron ore powder II and iron ore powder B as iron ore powder I.

[0016] Further preferably, in step (2), iron ore powder having a particle size of ≥3 mm, a proportion of ≥35 wt%, a spheroidization index of ≥0.6 and a loss on burn of ≥6 wt% is screened out.

[0017] In a specific implementation manner of the present invention, after iron ore powder I and iron ore powder II are determined, the dolomite powder ore bin is fixed, and iron ore powder I and iron ore powder II are selected from the adjacent ore bins respectively, and the discharge amount of each ore bin is determined according to the sintering production demand. The material is fed by a batching disc, and the material is discharged to the batching belt in the order of iron ore powder I, dolomite powder, and iron ore powder II. Then, it is transported to the stockpile sub-BLOCK with the homogeneous material and the remaining iron ore powder (the homogeneous material and the remaining iron ore powder will also be fed by the batching disc to the batching belt) for mixing and stacking to obtain a mixed material.

[0018] In the present invention, the purpose of feeding in the order of iron ore powder I, dolomite powder, and iron ore powder II is to play a certain role in diversion and material preparation, so that the dolomite powder and the iron ore powder are mixed in advance, thereby making the sintered ore composition more uniform.

[0019] The homogenized material mentioned in the present invention refers to a mixture of secondary iron resources in a steel plant, and the mixture of secondary iron resources in a steel plant includes sintering dust, blast furnace gas ash, steel mill skin and steel slag.

[0020] In the present invention, except for limiting the feeding order of iron ore powder I, dolomite powder and iron ore powder II, there is no requirement for the feeding order of the homogenous material and the remaining iron ore powders. The homogenous material can be fed before iron ore powder I or after iron ore powder II, and there is no requirement for the feeding order between the homogenous material and the remaining iron ore powders.

[0021] Still taking the above-mentioned iron ore powder A, iron ore powder B, iron ore powder C, iron ore powder D and iron ore powder E as an example, in a specific implementation, after confirming that iron ore powder A and iron ore powder B are recorded as iron ore powder I and iron ore powder II, they are fed to the batching belt in the order of iron ore powder I, dolomite powder, and iron ore powder II, and then mixed with the homogenous material and iron ore powder C, iron ore powder D and iron ore powder E to form a pile to obtain a mixed material (there is no requirement for the feeding order of the homogenous material and iron ore powder C, iron ore powder D and iron ore powder E, and they can be fed before iron ore powder I or after iron ore powder II).

[0022] In a preferred embodiment, in step (3), the moisture content of the dolomite powder is ≤10wt%, more preferably 5-8wt%, because when the moisture content of the dolomite powder is too low, it is easy to cause the environmental problem of "dusting" during unloading, and when the moisture content is too high, it will cause logistics difficulties such as conveyor belt carrying and funnel clogging. Therefore, when the moisture content of the dolomite powder is controlled in the range of 5-8wt%, both environmental protection and logistics issues can be taken into account.

[0023] Furthermore, in step (3), the dolomite powder has a CaO content ≥ 29wt%, a MgO content ≥ 19wt%, a SiO2 content ≤ 4wt%, and a S content ≤ 0.035wt%.

[0024] Preferably, in step (3), the dolomite powder having a particle size of ≤3 mm accounts for ≥90wt%.

[0025] Furthermore, in step (3), the average particle size of the dolomite powder is less than 1.5 mm.

[0026] In the present invention, in step (3), the content of dolomite powder in the mixed material is 5.8-7wt%.

[0027] In the preferred case of step (3), the content of the homogenous material in the mixed material is 2-8wt%.

[0028] The present invention has the following advantages:

[0029] 1) It solves the problem of insufficient flux crushing capacity after the large-scale transformation of the sintering machine, and reduces the pressure of sintering mixture batching;

[0030] 2) The process of adding dolomite to the mixed ore has the effect of diversion and granulation, so that the dolomite particles are evenly wrapped around the limonite particles, which promotes the sintering of limonite and improves the quality of sintered ore. After multiple mixing, the distribution of dolomite powder in the sintering mixture is more uniform, creating better raw material conditions for the stability of sintered ore quality. DETAILED DESCRIPTION

[0031] The specific implementation of the present invention is described in detail below in conjunction with the examples. It should be understood that the specific implementation described herein is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0033] Example 1

[0034] (1) Providing ore powder for mixing and building piles: ore powder for mixing and building piles includes iron ore powder A (high silicon Brazilian powder), iron ore powder B (Ka powder), iron ore powder C (Argentina powder (South Africa)), iron ore powder D (King powder), iron ore powder E (super special powder), iron ore powder F (new MAC powder) and iron ore powder G (FMG mixed powder);

[0035] (2) Ore powder screening: The particle size analysis, ball formation index and burnout test were performed on each iron ore powder. The proportion of each iron ore powder with a particle size of ≥3 mm, ball formation index (K), burnout (LOI) and content in the mixed material are shown in Table 1 (the content of limonite in the ore powder used for mixing and building piles is 58.1wt%, and the content of Fe2O3·nH2O in limonite accounts for 50wt% or more of the iron oxide content). After screening, the iron ore powders with a particle size of ≥3 mm account for ≥30wt%, ball formation index ≥0.35 and burnout ≥6wt% include king powder, super special powder, New MAC powder and FMG mixed powder. The above four iron ore powders are all limonite. The content of Fe2O3·nH2O in these four limonite accounts for 90wt%, 75wt%, 55wt% and 65wt% of the iron oxide content respectively. The content of King powder, Super special powder, new MAC powder and FMG mixed powder in the mixed material is further compared. After comparison, the content of new MAC powder and FMG mixed powder in the mixed material is the largest among King powder, Super special powder, new MAC powder and FMG mixed powder. Therefore, MAC powder and FMG mixed powder are selected and recorded as iron ore powder I and iron ore powder II.

[0036] (3) Mixing and building a pile: fix the dolomite powder ore slot, select iron ore powder I and iron ore powder II from its adjacent ore slots, and determine the amount of material discharged from each ore slot according to the sintering production requirements. The material is fed by the batching disc, and the mixture is mixed in order according to the following steps: iron ore powder I, dolomite powder (water content 8wt%, CaO content 32.09wt%, MgO content 19.92wt%, SiO2 content 1.5wt%, S content 0.02wt%, particle size ≤3mm accounting for 92.08wt%, average The material of particle size 1.3mm) and iron ore powder II are fed to the batching belt in sequence, and then transported to the stockpile block with homogeneous material and high silicon Brazilian powder, Ka powder, A powder (South Africa), King powder and super special powder (homogeneous material and high silicon Brazilian powder, Ka powder, A powder (South Africa), King powder and super special powder will also be fed to the batching belt by the batching disc feeding) to obtain mixed material (the content of dolomite powder and homogeneous material in the mixed material is also shown in Table 1);

[0037] Table 1

[0038]

[0039]

[0040] The mixed material obtained in the above embodiment has a TFe content of 56.6wt%, a MgO content of 1.46wt%, and a SiO2 content of 5.06wt%. The sintered ore produced from the mixed material has good quality and meets the production requirements of blast furnaces.

[0041] Example 2

[0042] (1) Providing ore powder for mixing and building piles: ore powder for mixing and building piles includes iron ore powder A (high silicon Brazilian powder), iron ore powder B (Ka powder), iron ore powder C (Argentina powder (South Africa)), iron ore powder D (King powder), iron ore powder E (super special powder), iron ore powder F (new MAC powder) and iron ore powder G (FMG mixed powder);

[0043] (2) Screening of ore powder: The particle size analysis, ball formation index and burnout test were performed on each iron ore powder. The proportion of particle size ≥3 mm, ball formation index (K), burnout (LOI) and content of each iron ore powder in the mixed material are shown in Table 2 (the content of limonite in the ore powder used for mixed pile construction is 63.2wt%, and the content of Fe2O3·nH2O in limonite accounts for 50wt% or more of the iron oxide content). After screening, the iron ore powders with particle size ≥3 mm account for ≥30wt%, ball formation index ≥0.35 and burnout ≥6wt% include king powder, super Special powder, new MAC powder, FMG mixed powder, the above four kinds of iron ore powder are all limonite, the content of Fe2O3·nH2O in these four kinds of limonite accounts for 90wt%, 75wt%, 55wt% and 65wt% of the content of iron oxide respectively, further compare the content of king powder, super special powder, new MAC powder and FMG mixed powder in the mixed material, after comparison, at this time, among king powder, super special powder, new MAC powder and FMG mixed powder, the content of new MAC powder and king powder in the mixed material is the largest, so iron MAC powder and king powder are selected as iron ore powder Ⅰ and iron ore powder Ⅱ;

[0044] (3) Mixing and building a pile: fix the dolomite powder ore slot, select iron ore powder I and iron ore powder II in its adjacent ore slots, and determine the amount of material discharged from each ore slot according to the sintering production requirements. The material is fed by the batching disc, and the mixture is mixed in order according to the following steps: iron ore powder I, dolomite powder (water content 8wt%, CaO content 32.09wt%, MgO content 19.92wt%, SiO2 content 1.5wt%, S content 0.02wt%, particle size ≤3mm accounting for 92.08wt%, average particle size 1 .3mm), iron ore powder II are fed to the batching belt in order, and then transported to the stockpile sub-BLOCK for mixing and heaping with homogeneous material and high silicon Brazilian powder, Ka powder, A powder (South Africa), super special powder and FMG mixed powder (homogeneous material and high silicon Brazilian powder, Ka powder, A powder (South Africa), super special powder and FMG mixed powder will also be fed to the batching belt by the batching disc feeding) to obtain mixed material (the content of dolomite powder and homogeneous material in the mixed material is also shown in Table 2);

[0045] Table 2

[0046]

[0047] The mixed material obtained in the above embodiment has a TFe content of 56.4wt%, a MgO content of 1.48wt%, and a SiO2 content of 5.11wt%. The sintered ore produced from the mixed material has good quality and meets the production requirements of blast furnaces.

[0048] It can be seen from the above results that the components such as TFe, MgO content, SiO2 content, etc. of the mixed material obtained after the dolomite powder of the present invention is mixed and piled up all meet the technical parameters of sintering raw materials and can meet the sintering production requirements.

[0049] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0050] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for mixing dolomite powder into a mixed ore pile, characterized in that: The method comprises the following steps: (1) Providing ore powder for mixing and building a pile: the ore powder for mixing and building a pile comprises at least three kinds of iron ore powder; (2) Screening of ore powder: particle size analysis, ball formation index and burnout test are performed on each type of iron ore powder, and iron ore powder with a particle size of ≥3 mm, a proportion of ≥30 wt%, a ball formation index of ≥0.35 and a burnout of ≥6 wt% is screened out. When there are two types of iron ore powder screened out, they are recorded as iron ore powder I and iron ore powder II respectively; when there are more than two types of iron ore powder screened out, the two types of iron ore powder with the largest content in the mixed material obtained after mixing and building a pile are selected from them, and they are recorded as iron ore powder I and iron ore powder II respectively; (3) Mixing and piling: The iron ore powder I, dolomite powder, and iron ore powder II are fed to the batching belt in the order of feeding, and then mixed with the homogenized material and the remaining iron ore powder to form a pile to obtain a mixed material.

2. The method for mixing dolomite powder into a mixed ore pile according to claim 1, characterized in that: In step (1), the content of limonite in the mixed ore powder for pile building is ≥40wt%.

3. The method for mixing dolomite powder into a mixed ore pile according to claim 1, characterized in that: In step (2), iron ore powder with a particle size of ≥3 mm, a proportion of ≥35 wt%, a spheroidization index of ≥0.6 and a burnout of ≥6 wt% is screened out.

4. The method for mixing dolomite powder into a mixed ore pile according to claim 1, characterized in that: In step (3), the moisture content of the dolomite powder is ≤10wt%.

5. The method for mixing dolomite powder into a mixed ore pile according to claim 4, characterized in that: In step (3), the moisture content of the dolomite powder is 5-8wt%.

6. The method for mixing dolomite powder into a mixed ore pile according to claim 1, characterized in that: In step (3), the dolomite powder has a CaO content of ≥29wt%, a MgO content of ≥19wt%, a SiO2 content of ≤4wt%, and a S content of ≤0.035wt%.

7. The method for mixing dolomite powder into a mixed ore pile according to claim 1, characterized in that: In step (3), the dolomite powder having a particle size of ≤3 mm accounts for ≥90wt%.

8. The method for mixing dolomite powder into a mixing ore pile according to claim 1 or 7, characterized in that: In step (3), the average particle size of the dolomite powder is less than 1.5 mm.

9. The method for mixing dolomite powder into a mixed ore pile according to claim 1, characterized in that: In step (3), the content of dolomite powder in the mixed material is 5.8-7wt%.

10. The method for mixing dolomite powder into a mixing ore pile according to claim 1, characterized in that: In step (3), the content of the homogenized material in the mixed material is 2-8wt%.

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