Hot briquetted iron

Abstract

The invention relates to an HBI with an improved geometry.

Description

[0001] The invention relates to a hot-briquetted iron.

[0002] When iron ore carriers are reduced to directly reduced iron (DRI), the elemental iron content increases and can be described by the degree of metallization: Degree of metallization [%] = 100 * elemental Fe [%] / total Fe [%]. Due to the contact of the iron ore carrier surface with a hot reducing gas, the reaction processes and ultimately the metallization process begin from the outside in. While complete reduction, i.e., a degree of metallization of 100%, is theoretically possible, in practice, economic efficiency and thus the time required for reduction play a key role. Therefore, a degree of metallization of up to 100%, particularly up to 98%, is targeted. A degree of metallization of at least 80%, particularly 85%, preferably at least 90%, more preferably at least 92%, and most preferably 94%, is the goal in the direct reduction process. Iron ore carriers can be provided in the form of sinter, pellets, and / or iron ore / lump ores.

[0003] Hot briquetted iron (HBI) is a compacted form of DRI which is compressed at a temperature, for example, between 400 and 800 °C and can therefore have an average density of 3000 kg / m 3 and more, for example up to 8000 kg / m 3 or less, in particular up to 7000 kg / m 3 , preferably up to 6000 kg / m 3 .

[0004] The experts know what an HBI means.

[0005] Average density is the density from the surface to the core of the HBI as an average value, although the density can vary locally near the surface up to the core.

[0006] Due to its compaction, HBI exhibits lower porosity and, consequently, lower reactivity with oxygen compared to DRI. Furthermore, there is virtually no risk of "spontaneous combustion" during storage and contact with water. HBI was therefore developed to overcome the problems associated with the transport and handling of DRI.

[0007] HBI is used in iron and steel production, as a blast furnace feedstock, as a melting feedstock in electric furnaces, and also as a coolant in oxygen-blast converters.

[0008] Methods and devices for producing HBI are known, see for example WO 2023 / 086002 A1. The geometry of the HBI is usually a kind of pillow shape in different dimensions, see for example https: / / sahutconreur.com / en / equipment-briquetting-hbi.html or https: / / www.midrex.com / tech-article / hot-briquetted-iron-steels-most-versatile-metallic-part-1-starting-with-the-basics / .

[0009] An egg or spherical shape is also known, see for example JP 2008-127580 A.

[0010] The standard geometry of the HBI also leads to disadvantages during transport and use in smelters. These can include, among others: High noise emissions during handling / loading; high dust emissions during handling / loading; during handling but also when conveying via belts due to the size and high mass, damage to bunkers / transfer points / belts can occur; asymmetrical, therefore poor / irregular melting behavior in the melter; low degree of gaps, thus little space for additives in particular in the melter -> segregation, inhomogeneous distribution; unfavorable pouring behavior; low surface-to-volume ratio -> poor melting behavior due to poor heat transfer into the interior of the HBI; can lead to the formation of so-called icebergs when used in the melter.

[0011] The task is to provide a hot-briquetted iron that can reduce or even eliminate at least one or more of the aforementioned disadvantages.

[0012] The object is achieved with a hot-briquetted iron according to claim 1. Further advantageous embodiments are set out in the subclaims.

[0013] The invention relates to a hot-briquetted iron having an average density of at least 3000 kg / m 3< and, for example, up to 8000 kg / m 3< or less, wherein the geometry of the hot-briquetted iron has a shape of a cone or a shape of a pyramid.

[0014] The shape of a cone essentially has a circular base with a circular base edge and a side surface that tapers to a point or apex above the base.

[0015] The shape of a pyramid essentially has an n-gon as a base with n base edges and correspondingly n sides with n side edges, which converge to a point or vertex above the base. The pyramid is therefore synonymous with numerous possible shapes. n is an integer with n = 3 to 30. For example, a design can be a three-sided pyramid with n = 3; a four-sided pyramid with n = 4; a five-sided pyramid with n = 5; a six-sided pyramid with n = 6; a seven-sided pyramid with n = 7; an eight-sided pyramid with n = 8; a nine-sided pyramid with n = 9; a ten-sided pyramid with n = 10; an eleven-sided pyramid with n = 11; and a twelve-sided pyramid with n = 12. Further versions with up to n=30 pages are conceivable, in particular up to n=20 pages, preferably up to n=15 pages.

[0016] With increasing n and the associated increase in the side surfaces, the surface area of ​​the pyramid can be increased, especially while keeping the height of the pyramid constant.

[0017] The apex and base edge of the cone, as well as the apex, n-corners with n-base edges and n-side edges of the pyramid, describe the "ideal" shape of the respective geometry of the hot-briquetted iron.

[0018] According to one embodiment, the geometry of the hot-briquetted iron may have the shape of a double cone or the shape of a double pyramid.

[0019] Double means that the respective tips of the double cone as well as the double pyramid point apart, whereby the base is no longer visible.

[0020] The tips and base edges of the double cone as well as the tips, n-corners with n-base edges and 2 x n-side edges of the double pyramid describe the "ideal" shape of the respective geometry of the hot-briquetted iron.

[0021] According to one embodiment, the cone or pyramid can have a height between 20 and 200 mm, in particular up to 150 mm, preferably up to 120 mm, preferably up to 90 mm. In the embodiment of the double cone or double pyramid, the height can be between 30 and 250 mm, in particular up to 200 mm, preferably up to 150 mm, preferably up to 100 mm.

[0022] According to one embodiment, the pyramid or the double pyramid can each have a base edge with a length between 10 and 120 mm, in particular up to 100 mm, preferably up to 80 mm, and more preferably up to 70 mm. Particularly preferably, all base edges have the same length.

[0023] According to one embodiment, the pyramid or the double pyramid can each have a side edge with a length between 10 and 250 mm, in particular up to 200 mm, preferably up to 150 mm, preferably up to 100 mm, particularly preferably up to 80 mm. Particularly preferably, all side edges have the same length.

[0024] In order to particularly reduce the susceptibility to damage, one embodiment may feature a rounded portion instead of a cone tip or a rounded portion instead of a pyramid tip. In the design of a double cone or a double pyramid, rounded portions may be used instead of tips.

[0025] Furthermore, alternatively or additionally, a pyramid or a double pyramid can also be designed with curves instead of corners. This also allows for easier production of the negative molds used to produce the HBI, as is known from the prior art.

[0026] According to one embodiment, the curves instead of a point or points as well as the curves instead of corners in a pyramid or a double pyramid can each have a radius of 2 to 25 mm, in particular up to 23 mm, preferably up to 20 mm, preferably up to 17 mm, particularly preferably up to 15 mm.

[0027] The determination of heights, lengths and radii as well as associated surfaces and volumes of objects, thus especially here on the hot briquetted

[0028] Iron is state-of-the-art. Heights and lengths can be determined most easily with a caliper or a ruler.

[0029] The advantages of the hot-briquetted iron according to the invention compared to the standard geometry can be reflected in at least one or more of the following characteristics: comparable transport and shipping; potentially constant average density with possible changes in bulk density; potentially higher bulk density with smaller (symmetrical) material and thus higher mass with the same transport volume; potentially smaller dimensions; potentially better logistical handling; potentially lower noise emissions during handling / loading; potentially lower dust emissions; possibly symmetrical; potentially even and / or faster melting; possibly lower mass per HBI; less damage upon impact -> maintenance costs, etc.Lower in the burden; more favorable pouring behavior; possibly more interstices for aggregates in the melter; possibly larger surface-to-volume ratio per HBI; potentially better heat input during melting due to better heat transfer from the surfaces to the "interior"; potentially lower risk of spontaneous combustion during storage; potentially better waste heat transport due to a smaller void volume.

[0030] The hot-briquetted iron according to the present invention is preferably used as an iron carrier in an electric smelter.

[0031] Therefore, the use of the hot-briquetted irons according to the invention in an electric furnace of the OSBF (Open Slag Bath Furnace) type is particularly preferred. These include submerged electric arc furnaces, especially SAF (Submerged Electric Arc Furnaces), which are melting furnaces with arc resistance heating, which form arcs between the electrode and the solid and / or slag, or which heat the solid and / or slag using the Joule effect. In SAF, the electrode (or electrodes, if several are present) is immersed in the charge and / or slag. Depending on the functional principle / mode of operation, the submerged electric arc furnaces can be designed as alternating current submerged arc furnaces (SAFac) or direct current submerged arc furnaces (SAFdc).

[0032] Alternatively, the hot-briquetted irons according to the invention can also be used in an electrically operated melter with direct arc action, which deviates from the functional principle / mode of operation described above, a so-called EAF (Electric Arc Furnace), which forms arcs between the electrode and the melt. This includes the AC arc melting furnace (EAFac), the DC arc melting furnace (EAFdc), and the ladle furnace (LF).

[0033] The advantage of submerged arc furnaces (SAF) is that they operate in a reducing atmosphere, whereas direct arc furnaces (EAF) operate in an oxidizing atmosphere.

[0034] The invention is explained in more detail using the following embodiments in conjunction with the drawing.

[0035] In Figure 1Examples of "ideal" shapes of hot-briquetted iron are shown. On the left, a cone shape (1) is shown, which has a circular base with a circular base edge (G) and a funnel-shaped side surface tapering to a point or apex (P) above the base. Pyramid shapes (2), which have an n-gon (E) as a base with n base edges (G) and correspondingly n side surfaces with n side edges (S) converging to a point or apex (P) above the base, where n is an integer between 3 and 30, are shown in Figure 1 middle-left example with n=4 as a four-sided or square pyramid (2), in Figure 1 middle-right example with n=3 as a three-sided pyramid (2) and in Figure 1 shown on the right using the example with n=6 as a six-sided pyramid (2).

[0036] In Figure 2Examples of "ideal" shapes of hot-briquetted iron are shown. On the left, a double cone shape (1') is shown. On the right, a double pyramid shape (2') is shown, using the example of a four-sided double pyramid (2') with n=4. The difference from the cone (1) or pyramid (2) is that there are two points (P) pointing apart.

[0037] In Figure 3show three different "real" shapes of hot-briquetted iron produced under laboratory conditions. The symbolically represented dashed lines each correspond to an "ideal" form of the geometry. The "real" shape shown deviates from the "ideal" shape in the sense that both curves (R1) were created instead of points (P) and curves (R2) were created instead of corners (E). This can reduce the risk of damage to the hot-briquetted iron during transport and handling. The curves (R1) can be the same or identical to the curves (R2) or can differ from them, for example, so that (R1) > (R2). The curves (R1, R2) are designed with a radius [in mm], which can be influenced by a correspondingly adapted negative mold during the production of the HBI. However, a "real" shape can also be created, not shown here, which essentially corresponds to the "ideal" shape.The length (L2) of the base edges (G) and the length (L1) of the side edges (S) are shorter in the "real" form than in the "ideal" form. Each pair of base edges (G) of the "real" form does not meet at a corner (E) as in the "ideal" form, but is connected by a curve (R2). The side edges (S) of the "real" form also do not meet at a point (S) as in the "ideal" form, but instead each merge into the curve (R1) or are connected to each other by the curve (R1).

[0038] The left representation in Figure 3 shows a perspective view of a three-sided double pyramid (2'). The height, or total height from curve (R1) to curve (R1), determined using a caliper, is 70 mm. The lengths (L1) and (L2) are each 30 mm. The curves (R1) and (R2) each have a radius of 10 mm.

[0039] The middle representation in Figure 3shows a top view of a three-sided pyramid (2). The height, or total height from base to curve (R1), determined using a caliper, is 35 mm. The lengths (L1) and (L2) are each 30 mm. The curves (R1) and (R2) each have a radius of 10 mm.

[0040] The right representation in Figure 3 shows a top view of a four-sided pyramid (2). The height, or total height from base to curve (R1), determined using a caliper, is 30 mm. The lengths (L1) and (L2) are each 25 mm. The curves (R1) and (R2) each have a radius of 5 mm.

Claims

1. Hot-briquetted iron with an average density of at least 3000 kg / m 3 , characterized in that the geometry of the hot-briquetted iron has a shape of a cone (1) or a shape of a pyramid (2).

2. Hot-briquetted iron according to claim 1, wherein the geometry of the hot-briquetted iron has the shape of a double cone (1') or the shape of a double pyramid (2`).

3. Hot briquetted iron according to one of the preceding claims, wherein the cone (1) or the pyramid (2) has a height (H) between 20 to 200 mm or the double cone (1') or the double pyramid (2') has a height (H) between 30 to 250 mm.

4. Hot briquetted iron according to one of the preceding claims, wherein the pyramid (2) or the double pyramid (2') has base edges (G) each with a length (L2) between 10 and 120 mm.

5. Hot briquetted iron according to one of the preceding claims, wherein the pyramid (2) or the double pyramid (2') has side edges (S) each with a length (L1) between 10 and 250 mm.

6. Hot briquetted iron according to one of the preceding claims, wherein the cone (1) or double cone (1') or the pyramid (2) or the double pyramid (2') has curves (R1) instead of a tip (S) or instead of tips (S) with a radius of 2 to 25 mm each.

7. Hot briquetted iron according to one of the preceding claims, wherein the pyramid (2) or the double pyramid (2') has curves (R2) instead of corners (E) with a radius of 2 to 25 mm each.

Images