Optimal melting of compressed DRI

Abstract

The present invention relates to a method for melting DRI (20, 90) composed at least in part of HBI (40) and / or HCl (110) using a melting process, wherein the HBI (40) and / or HCl (110) are ground prior to being fed to the melting process, and the HBI (40) or HCl (110) fragments obtained during the grinding process are fed to the melting process.

Description

[Technical Field]

[0001] The present application relates to a method for melting a DRI composed at least in part of HBI and / or HCl by a melting process. [Background technology]

[0002] The reduction of iron oxide-containing materials by direct reduction with a reducing gas in a reduction unit, e.g., a fixed bed, a fluidized bed, or a fluidized bed, at high temperatures is known. The solid product of direct reduction is known as sponge iron or direct reduced iron (DRI), which is highly porous and therefore highly reactive, e.g., to oxidation. In the course of its further processing, DRI is usually melted.

[0003] To reduce reactivity and, as a result, simplify further processing, DRI is often compressed at a high temperature, i.e., as hot sponge iron or hot direct reduced iron (HDRI). The product of compression is hot briquetted sponge iron, or hot briquetted iron (HBI), for example, in the case of briquettes, or hot pressed sponge iron, or hot pressed iron (HCl), for example, in the case of DRI production in a fluidized bed or fluidized bed. In particular, in the case of fine HDRI dust, for example, from a fluidized bed or fluidized bed process, compression to HBI or HCl helps to avoid yield losses due to dust loss and quality loss.

[0004] 5.0g / cm 3 The current size of globally available HBI briquettes that can be transported by ship based on their apparent density exceeding 106 x 48 x 33 mm is the result of an effort to achieve the best possible HBI performance with as few briquetting machines as possible. The apparent density of HCI is lower than that of HBI, typically 3.5-4.2 g / cm. 3 and therefore not suitable for transport by ship according to the International Maritime Organization (IMO). The size of HCI can also be smaller than that of HBI, for example 50 x 38 x 22 mm.

[0005] When compacted DRI, such as HBI or HCl, is melted during further processing, for example in an arc furnace, melting unit, or submerged arc furnace (SAF), the flexibility of the addition rate to the melting process is determined by the time it takes for the briquettes to melt therein. This also depends on the energy output that can be supplied to the melting process, which can in turn affect the productivity of the melting process. Compared to melting DRI, HBI has a disadvantage in this respect. Summary of the Invention [Problem to be solved by the invention]

[0006] A method should be presented that makes it possible to reduce or avoid at least some of the above drawbacks when using compressed DRI. [Means for solving the problem]

[0007] The purpose of this is to This is achieved by a method of melting sponge iron (DRI) at least partially composed of hot briquette sponge iron (HBI) and / or hot compacted sponge iron (HCI) using a melting process, The hot briquette sponge iron (HBI) and / or hot compressed sponge iron (HCI) are crushed before being fed to the melting process, and the hot briquette sponge iron (HBI) and / or hot compressed sponge iron (HCI) fragments obtained during crushing are fed to the melting process.

[0008] As explained in the introduction, DRI can be uncompressed or compressed. HBI and HCI are special cases of the general term DRI, and they refer to compressed DRI.

[0009] If the temperature of the briquetting DRI exceeds 650°C, the product of DRI compaction will have an apparent density of 5.0 g / cm 3If the apparent density exceeds 5.0 g / cm3, it is called hot briquette sponge iron or hot briquette iron (HBI). 3 If the temperature of the DRI being briquetted is below 650°C, the term hot pressed iron sponge or hot pressed iron (HCI) is common.

[0010] HBI and HCI should be understood in the context of this application as defined above.

[0011] Information regarding HBI can be found, for example, in HOT BRIQUETTED IRON (HBI) QUALITY ASSESSMENT GUIDE, International Iron Metallics Association, August 2018, and current International Maritime Organization (IMO) regulations.

[0012] The melting process is preferably carried out using electrical energy. [Effects of the Invention]

[0013] Grinding produces smaller fragments than the fragments formed by HBI or HCl. The time required to melt the fragments is further reduced. Therefore, the method of the present invention allows for a higher addition rate to the melting process than would be possible if HBI or HCl were added to the melting process without the grinding method of the present invention. As a result, it is not necessary to increase the addition rate by increasing the energy output supplied to the melting process, as has been the case until now, which can have an adverse effect on productivity. Therefore, the disadvantages compared to melting uncompressed DRI are at least reduced.

[0014] Preferably, the comminution is a crushing operation, which is carried out in a crusher such as a crusher, and is preferably carried out in at least two stages.

[0015] The crushing operation produces pieces in the form of HBI or HCl fragments.

[0016] The crushing operation is carried out by a crusher, which may be a single crusher or a crusher system having multiple crushers arranged, for example, in two or more successive stages, with the downstream stage receiving the chips or pieces produced in the previous stage as input material for the crushing that takes place therein. A crushing operation carried out in two or more successive stages is a multi-stage process.

[0017] Crushing operations are used to break down solid materials, and comminution is achieved by breaking down said materials through a crushing process in a crusher, such as a grinder.

[0018] The material is preferably ground to a fragment size, also referred to as 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 ranges here include the respective limits. The upper limit of the size of the fragments preferably obtained by grinding is preferably 31.5 mm, more preferably 25 mm, and very particularly preferably 16 mm. The lower limit of the size of the fragments preferably obtained by grinding is preferably 3.35 mm, particularly preferably 6.3 mm.

[0019] This size has been found to be advantageous with regard to effectiveness during melting, which is the object of the present invention.

[0020] The particle size mentioned above refers to the American standard ASTM E11.

[0021] In the process of grinding to a particle size according to the above range of 3.35 to 31.5 mm or the preferred and particularly preferred sub-ranges thereof, some smaller fragments and possibly also some larger fragments are obtained.

[0022] According to one embodiment, the fragments obtained during grinding are fed to the melting process regardless of whether they are actually within the range of 3.35 to 31.5 mm / preferred and particularly preferred sub-ranges thereof. Thus, the melting process is fed not only with fragments having a particle size within the above-mentioned range of 3.35 to 31.5 mm / preferred and particularly preferred sub-ranges thereof, but also with fragments outside this range or sub-range.

[0023] According to another embodiment, which will be described in more detail below, a minimum size of the debris formed during grinding is defined, and debris formed during grinding that is less than the minimum size is removed, and only debris that is greater than the minimum size is fed to the melting process.

[0024] According to one embodiment, the fragments obtained during grinding are fed to the melting process only if they are currently within the above-mentioned range of 3.35 to 31.5 mm / preferred and particularly preferred sub-ranges thereof.

[0025] Preferably, the DRI is composed solely of HBI and / or HCl.

[0026] According to a preferred embodiment, the melting process comprises: -Melting in an electric arc furnace (EAF), -Melting in a Submerged Arc Furnace (SAF), -Melting in an open slag bath furnace (OSBF), -Melting in the melting unit, -Melting in converters, The method includes at least one of the group of methods consisting of:

[0027] In the melting unit, melting is at least partly based on electrical energy.

[0028] The EAF, SAF, and OSBF should not be understood as melting units in the context of this application.

[0029] The converter is, for example, a steelmaking converter for producing steel.

[0030] According to one embodiment, a minimum size of debris formed during milling is defined, and debris formed during milling that is less than the minimum size is removed.

[0031] Removal may be by sieving, for example.

[0032] Fragments below the minimum size may be fed, for example by bucket elevator or pneumatic conveying, to a process to produce HBI or HCl and subjected to compaction there along with the HDRI.

[0033] Fragments above a minimum size are at least partially fed into the melting process.

[0034] The above-mentioned characteristics, features, and advantages of the present invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in conjunction with the following description of the embodiments, which are set forth in more detail in conjunction with schematic and exemplary drawings. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 shows a schematic representation of the implementation of an embodiment of the method of the present invention using HBI. [Figure 2] FIG. 1 is a schematic diagram illustrating the implementation of one embodiment of the method of the present invention using HCl. DETAILED DESCRIPTION OF THE INVENTION

[0036] Example 1 shows how DRI 20, in this case HDRI, produced in a reduction unit 10 based on fixed-bed or fluidized-bed or fluidized-bed direct reduction is compressed into HBI 40 in a briquetting device 30. The HBI is optionally transported to another location, for example by rail or ship, and then fed to a melting process in a melter 50. The melter may be, for example, -Melting in an electric arc furnace (EAF), -Melting in a Submerged Arc Furnace (SAF), -Melting in an open slag bath furnace (OSBF), -Melting in the melting unit, -Melting in converters, The apparatus is suitable for performing at least one of the methods consisting of:

[0037] Upstream of the feed, in the illustrated example via an intermediate bunker 60, but also directly, i.e. without an intermediate bunker, the HBI 40 is crushed in a crushing device 70, which may be single-stage or multi-stage, for example two-stage. In the illustrated example, the crushing device is a crusher. The HBI 40 fragments obtained during crushing are fed to the melting device 50 via the intermediate bunker 60.

[0038] 2 shows how the DRI 90, in this case HDRI, produced in a reduction unit 80 based on direct reduction in a fluidized or fluidized bed is compressed in a compression device 100 to HCl 110. The HCl 110 is then fed to a melting process in a melter 120 located at a compression location reasonably close to the plant network. The melter may be, for example: -Melting in an electric arc furnace (EAF), -Melting in a Submerged Arc Furnace (SAF), -Melting in an open slag bath furnace (OSBF), -Melting in the melting unit, -Melting in a converter vessel, The apparatus is suitable for performing at least one of the methods consisting of:

[0039] Upstream of the feed, in the illustrated example via an intermediate bunker 130, but also directly, i.e. without an intermediate bunker, the HCl 110 is crushed in a crushing device 140, which may be single-stage or multi-stage, for example two-stage. In the illustrated example, the crushing device is a crusher. Fragments 150a, 150b of the HCl 110 obtained during crushing are screened in a screening device 160. Only the fragments 150a exceeding a minimum size are fed to the melting device 120 via the intermediate bunker 130. Fragments 150b below the minimum size are fed to a compacting device 100, where they are compacted together with the HDRI.

[0040] Although the present invention has been illustrated and explained in more detail by means of preferred exemplary embodiments, the invention is not limited to the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of protection of the present invention. [Explanation of symbols]

[0041] 10 Redemption Units 20 DRI 30 Briquetting equipment 40 HBI 50 Melting Device 60 Intermediate Bank 70 Crushing Equipment 80 Redemption Units 90 DRI 100 Compression Device 110 HCI 120 Melting Device 130 Intermediate Bank 140 Crushing Equipment 150a, 150b fragments 160 Screening equipment

Claims

1. 1. A method for melting sponge iron (DRI) (20, 90) at least partly composed of hot briquette sponge iron (HBI) (40) and / or hot compacted sponge iron (HCI) (110) by a melting process, comprising: The hot briquette sponge iron (HBI) (40) and / or hot compressed sponge iron (HCI) (110) are crushed before being fed to the melting process, and the pieces of the hot briquette sponge iron (HBI) (40) and / or hot compressed sponge iron (HCI) (110) obtained during crushing are fed to the melting process.

2. 2. A method according to claim 1, characterized in that the comminution is a crushing operation preferably carried out in at least two stages.

3. 3. The method according to claim 1 or 2, characterized in that the crushing results in 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. 4. The method according to claim 1, wherein the DRI (20, 90) is entirely composed of HBI (40) and / or HCI (110).

5. the melting process - 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 converters, 5. The method according to claim 1, comprising at least one of the group of methods consisting of:

6. 6. The method according to claim 1, wherein a minimum size is defined for the fragments formed during grinding, and fragments formed during grinding that are smaller than said minimum size are removed.

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