Optimized melting of compacted DRI
By crushing HBI or HCI before melting and controlling the fragment particle size, the problem of limited addition rate during the melting process of compacted DRI is solved, and more efficient melt production is achieved.
Patent Information
- Application Number
- CN202380087120.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-04-25
- Filing Date
- 2023-12-13
- Publication Date
- 2025-07-25
AI Technical Summary
In the prior art, compacted DRI (HBI or HCI) is limited in the addition rate during the melting process and has a high energy efficiency dependence, which affects productivity.
HBI or HCI is crushed before melting, and the resulting fragment particle size is controlled in the range of 3.35 mm to 31.5 mm, and is used during the melting process, preferably by a multi-stage crusher system.
The addition rate of the melting process is improved, the dependence on energy efficiency is reduced, and the production efficiency is improved.
Smart Images
Figure CN120380174A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to a method for melting DRI which consists of at least partially HBI and / or HCI by means of a melting process. Prior Art
[0002] The reduction of iron oxide-containing materials by direct reduction with a reducing gas at elevated temperatures in a reduction unit, for example in a fixed bed, fluidized bed or fluidized bed, is known. The solid product of direct reduction is called sponge iron or DRI direct reduced iron; it is very porous and therefore highly reactive, for example highly reactive to oxidation. During its further processing, DRI is usually melted.
[0003] In order to reduce reactivity and thus simplify further processing, DRI is usually compacted in the hot state, i.e. as HDRI hot direct reduced iron or hot sponge iron or hot direct reduced iron. The compacted product is called HBI hot briquetted iron or hot briquetted sponge iron, for example when producing briquettes, or HCI hot pressed iron or hot pressed sponge iron, for example in the case of producing DRI in a fluidized bed or fluidized bed. Especially in the case of fine-grained HDRI dust from a fluidized bed or fluidized bed process, compaction into HBI or HCI helps to avoid yield losses caused by dust loss and quality loss.
[0004] The common size of HBI briquettes with an apparent density greater than 5.0 g / cm 3 that can be shipped by ship is 106x 48x 33 mm; this is the result of efforts to achieve the greatest possible HBI efficiency with as few briquetting machines as possible. The apparent density of HCI is lower than that of HBI – usually in the range of 3.5 - 4.2 g / cm 3 – and is therefore not suitable for shipping by ship according to the IMO International Maritime Organization. The size of HCI can also be smaller than that of HBI, for example 50x 38x 22 mm.
[0005] If the compacted DRI, such as HBI or HCI, is melted in its further processing in, for example, an electric arc furnace, melting unit or SAF submerged arc furnace, the tolerance of the rate added to the melting process depends on the time required for the briquettes to melt therein. This also depends on the energy efficiency available to the melting process, which in turn affects its productivity. HBI has disadvantages in this regard compared to the melting of DRI. Summary of the Invention
[0007] Technical Objectives
[0008] A method should be proposed that can reduce or avoid at least some of the above disadvantages when using compacted DRI.
[0009] Achievement of Technical Objectives
[0010] This object is achieved by a method of melting at least part of the direct reduced iron (DRI) consisting of hot briquetted iron (HBI) and / or hot compacted iron (HCI) by means of a melting process,
[0011] wherein the hot briquetted iron (HBI) and / or hot compacted iron (HCI) is crushed before being supplied to the melting process, and the fragments of the hot briquetted iron (HBI) and / or hot compacted iron (HCI) obtained during the crushing process are supplied to the melting process.
[0012] As described in the introduction, the DRI can be uncompacted or compacted. HBI and HCI are specific cases of the general term DRI; they refer to compacted DRI.
[0013] If the temperature of the compacted DRI is higher than 650 °C, the product of DRI compaction is called HBI hot briquetted iron or hot briquetted sponge iron when its (apparent) density is higher than 5.0 g / cm 3 When. For the compacted DRI that does not fully meet these criteria, i.e., when the (apparent) density is less than or equal to 5.0 g / cm 3 and / or the temperature of the compacted DRI is 650 °C or lower, the term HCI hot pressed iron or hot pressed sponge iron is common.
[0014] HBI and HCI should be understood as defined above in this application.
[0015] Information on HBI can be found, for example, in the HOT BRIQUETTED IRON (HBI) QUALITY ASSESSMENT GUIDE, International Iron Metallics Association, August 2018 and the current International Maritime Organization (IMO) regulations.
[0016] The melting process is preferably carried out using electrical energy.
[0017] Advantages of the invention
[0018] The fragments obtained by crushing are smaller than the HBI or HCI used to form them. The time required for melting the fragments is less. Therefore, compared with supplying HBI or HCI to the melting process without the crushing of the present invention, the method of the present invention enables a higher rate of addition to the melting process. Therefore, it is not necessary to rely on improving the energy efficiency of the supply to the melting process to increase the addition rate as has been done hitherto, and the improvement of energy efficiency has an adverse effect on productivity. Therefore, at least the disadvantages compared with the melting of uncompacted DRI are reduced.
[0019] Preferably, the crushing is a crushing operation; this is carried out in a crusher such as a jaw crusher and is carried out in at least two stages preferably.
[0020] The crushing operation produces fragments in the form of HBI or HCI shards.
[0021] The crushing operation is carried out by means of a crusher, and a single crusher or a crusher system with multiple crushers, for example arranged in multiple successive stages, can be used, where the fragments or shards generated in the previous stage are supplied to the downstream stage as input material for comminution therein. The crushing operation carried out by means of multiple successive stages is a multi-stage process.
[0022] The crushing operation is used to comminute solid materials, which is achieved by crushing via a crushing process in a crusher such as a crusher.
[0023] It is preferably comminuted to a fragment size, also known as the particle size, in the range of 3.35 mm to 31.5 mm, preferably 3.35 mm to 25 mm, particularly preferably 6.3 mm to 16 mm. The limits of this range are included herein. The upper limit of the fragment size preferably obtained in comminution is preferably 31.5 mm, more preferably 25 mm, and very particularly preferably 16 mm. The lower limit of the fragment size preferably obtained in comminution is preferably 3.35 mm, particularly preferably 6.3 mm.
[0024] This size has been found to be beneficial for the effects during the melting process pursued by the present invention.
[0025] The above particle size refers to the American standard ASTM E11.
[0026] During the comminution to a particle size according to the above range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges, in practice, some smaller fragments are also obtained and optionally some larger fragments are also obtained.
[0027] According to one embodiment, the fragments obtained during the crushing process are supplied to the melting process regardless of whether they are actually within the above range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges. Thus, not only fragments with a particle size within the above range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges are supplied to the melting process, but also fragments outside this range or sub-range are supplied.
[0028] According to another embodiment explained in more detail below, the minimum size of the fragments formed during the crushing process is defined, and the fragments formed during the crushing process that are smaller than this minimum size are separated out, and only the fragments larger than this minimum size are supplied to the melting process.
[0029] According to one embodiment, the fragments obtained during the crushing process are only supplied to the melting process if they are actually within the above range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges.
[0030] Preferably, the DRI consists entirely of HBI and / or HCI.
[0031] According to a preferred embodiment, the melting process comprises at least one member of the following methods:
[0032] - Melting in an electric arc furnace (EAF),
[0033] - Melting in a submerged arc furnace (SAF),
[0034] - Melting in an open slag bath furnace (OSBF),
[0035] - Melting in a melting unit,
[0036] - Melting in a converter vessel.
[0037] In the melting unit, the melting is at least partially based on electrical energy.
[0038] The EAF, SAF, and OSBF should not be understood as melting units in this application.
[0039] The converter vessel is, for example, a steelmaking converter used for producing steel.
[0040] According to one embodiment, the minimum size of the fragments formed during the crushing process is defined, and the fragments formed during the crushing process that are smaller than this minimum size are separated out.
[0041] The separation is carried out, for example, by screening.
[0042] The fragments smaller than this minimum size can be supplied to the process for producing HBI or HCI, for example, by means of a bucket elevator or pneumatic conveying, to be compacted here together with the HDRI.
[0043] The fragments larger than this minimum size are at least partially supplied to the melting process. Brief Description of the Drawings
[0045] In connection with the following description of the embodiments, the above-mentioned properties, features, and advantages of the present invention, as well as the ways and means of their implementation, will become clearer and more readily understandable. These embodiments are described in more detail in conjunction with the schematic and exemplary drawings. In the drawings:
[0046] Figure 1 Schematically shows the execution of one embodiment of the method of the present invention using HBI.
[0047] Figure 2 Schematically shows the execution of one embodiment of the method of the present invention using HCI.
[0048] Description of the Embodiments Embodiment
[0049] Figure 1 Shows how the DRI 20, in the present case HDRI, produced in the reduction unit 10 based on direct reduction in a fixed bed or fluidized bed or fluidized bath, is compacted into HBI 40 in the briquetting device 30. Optionally, after transportation to another location, for example by rail or by ship, the HBI is supplied to the melting process in the melting device 50. The melting device is, for example, a device belonging to the members suitable for carrying out the following methods:
[0050] - Melting in an electric arc furnace (EAF),
[0051] - Melting in a submerged arc furnace SAF,
[0052] - Melting in an open slag bath furnace OSBF,
[0053] - Melting in a melting unit
[0054] - Melting in a converter shell.
[0055] In the shown embodiment, it is carried out via the intermediate silo 60; but upstream of the supply that can also be carried out directly (i.e., without an intermediate silo), the HBI 40 is crushed in a crushing device 70 that can be single-stage or multi-stage, for example two-stage. In the shown embodiment, the crushing device is a crusher. The fragments of the HBI 40 obtained during the crushing process are supplied to the melting device 50 via the intermediate silo 60.
[0056] Figure 2 Shows how the DRI 90, in the present case HDRI, produced in the reduction unit 80 based on direct reduction in a fluidized bed or fluidized bath, is compacted into HCI 110 in the compaction device 100. Then the HCI 110 is supplied to the melting process in the melting device 120, which is optionally close to the compaction location in the plant network. The melting device is, for example, a device belonging to the members suitable for carrying out the following methods:
[0057] - Melting in an electric arc furnace (EAF),
[0058] - Melting in a submerged arc furnace SAF,
[0059] - Melting in an open slag bath furnace OSBF,
[0060] - Melting in a melting unit,
[0061] - Melting in a converter shell.
[0062] In the illustrated embodiment, it is carried out via the intermediate silo 130; however, it can also be carried out directly (i.e., without an intermediate silo). Upstream of the supply, the HCI 110 is crushed in a crushing device 140 which can be single-stage or multi-stage, for example two-stage. In the illustrated embodiment, the crushing device is a crusher. The fragments 150a, 150b of the HCI 110 obtained during the crushing process are screened in a screening device 160. Only the fragments 150a larger than the minimum size are supplied to the melting device 120 via the intermediate silo 130. The fragments 150b smaller than the minimum size are supplied to the compaction device 100 to be compacted together with the HDRI here.
[0063] Although the details of the present invention have been illustrated and described in more detail by preferred embodiments, the present invention is not limited by the disclosed examples, and those skilled in the art can derive other variations therefrom without departing from the scope of protection of the present invention.
[0064] List of reference numerals
[0065] 10 Reduction unit
[0066] 20 DRI
[0067] 30 Briquetting device
[0068] 40 HBI
[0069] 50 Melting device
[0070] 60 Intermediate silo
[0071] 70 Crushing device
[0072] 80 Reduction unit
[0073] 90 DRI
[0074] 100 Compaction device
[0075] 110 HCI
[0076] 120 Melting device
[0077] 130 Intermediate silo
[0078] 140 Crushing device
[0079] 150a, 150b Fragments
[0080] 160 Screening device
Claims
1. A method for melting at least part of the direct reduced iron DRI (20, 90) composed of hot briquetted iron HBI (40) and / or hot compressed iron HCI (110) by means of a melting process, wherein the hot briquetted iron HBI (40) and / or hot compressed iron HCI (110) are crushed before being supplied to the melting process, and the fragments of the hot briquetted iron HBI (40) and / or hot compressed iron HCI (110) obtained during the crushing process are supplied to the melting process.
2. The method according to claim 1, wherein The crushing is a crushing operation, and the crushing operation is carried out in at least two stages preferably.
3. The method according to claim 1 or 2, characterized in that Crush to a fragment size in the range of 3.35 mm to 31.5 mm, preferably 3.35 mm to 25 mm, particularly preferably 6.3 mm to 16 mm.
4. The method according to any one of claims 1 to 3, characterized in that The DRI (20, 90) consists entirely of HBI (40) and / or HCI (110).
5. The method according to any one of claims 1 to 4, characterized in that The melting process includes at least one member of the following methods: - Melting in an electric arc furnace (EAF), - Melting in a submerged arc furnace SAF, - Melting in an open slag bath furnace OSBF, - Melting in a melting unit, - Melting in a converter shell.
6. The method according to any one of claims 1 to 5, characterized in that Define the minimum size of the fragments formed during the crushing process, and separate the fragments formed during the crushing process that are smaller than the minimum size.