[0001 ] The invention relates to blast furnaces, and more precisely to cooling plates (or staves) that are fixed into blast furnaces.

[0002] As known by the man skilled in the art, a blast furnace generally comprises an inner wall partly covered with cooling plates (or staves).

[0003] In some embodiments these cooling plates (or staves) comprises a body having an inner (or hot) face comprising ribs parallel therebetween and separated by grooves also parallel therebetween. These ribs and grooves are arranged for allowing anchorage of a refractory lining (bricks or guniting) or of an accretion layer inside the blast furnace. [0004] When the body is made of copper or copper alloy, to offer a good thermal conductivity, the ribs are undergoing an early erosion because copper is not a wear resistant material.

[0005] To avoid such an early erosion, it is possible to increase the hardness of the ribs by introducing a steel piece in the grooves against the sidewalls of the ribs and the groove base, as described in the patent document EP 2285991 . Such steel pieces allow a good protection of the ribs, and allow also the staves to expand and deform freely because they are thermally compatible with the stave deformations. But, they are not properly cooled and could be washed out by the gas.

[0006] So, an objective of the invention is to improve the situation.

[0007] To this end, the invention relates to a cooling plate (or stave) for use in blast furnace and comprising a copper body having an inner face comprising ribs parallel therebetween, having first extremities opposite therebetween and separated by grooves having second extremities opposite therebetween.

[0008] This cooling plate (or stave) is characterized in that at least one of its ribs comprises at least one housing located between its first extremities and comprising at least one insert made of a wear resistant material that increases locally the wear resistance of this rib.

[0009] The cooling plate (or stave) of the invention may also comprise the following optional characteristics considered separately or according to all possible technical combinations:

- the wear resistant material may be chosen from a group comprising a metal and a ceramic;

> the wear resistant metal may be a wear-resistant steel or cast iron;

> the wear resistant ceramic may be silicon carbide, an extruded silicon carbide or other refractory material with good resistance to spalling and high hardness;

- in a first embodiment each housing may be a slot comprising an insert;

- in a second embodiment each housing may be a threaded hole in which a bolt, defining an insert, is screwed;

- at least one of the grooves may comprise at least a part of a multilayer protrusion extending between its second extremities and comprising at least one layer made of the wear resistant material that increases locally the wear resistance of neighboring ribs;

> the multilayer protrusion may comprise a first layer made of a material having a high thermal conductivity, and a second layer made of the wear resistant material and set on top of the first layer;

• the material of the first layer may be chosen from a group comprising a high conductivity metal copper and a copper alloy;

• each multilayer protrusion may be associated to a single groove; o the multilayer protrusion may further comprise a third layer sandwiched between the first and second layers and made of a material having a hardness intended for increasing hardness of the multilayer protrusion;

^■ the third layer may be made of a ceramic with good resistance to spalling and high hardness, such as SiC or extruded SiC;

• in a variant the first and second layers of each multilayer protrusion may be respectively associated to two neighboring grooves; o the first layer of each multilayer protrusion may comprise a slot extending between the second extremities and comprising an other insert made of a material having a hardness intended for increasing hardness of this first layer;

^■ the other insert may be made of a ceramic or of a wear-resistant and/or heat-resistant steel;

- the inner face of the copper body may comprise ribs having at least two different heights;

- the grooves may have a dovetail cross-section.

[0010] The invention also relates to a blast furnace comprising at least one cooling plate such as the one above introduced. [0011] Other characteristics and advantages of the invention will emerge clearly from the description of it that is given below by way of an indication and which is in no way restrictive, with reference to the appended figures in which:

- figure 1 illustrates schematically, in a perspective view, a part of a first example of embodiment of a cooling plate according to the invention,

- figure 2 illustrates schematically, in a cross section view, a part of a second example of embodiment of a cooling plate according to the invention, - figure 3 illustrates schematically, in a cross section view, a variant of the cooling plate illustrated in figure 2,

- figure 4 illustrates schematically, in a cross section view, a part of a third example of embodiment of a cooling plate according to the invention,

- figure 5 illustrates schematically, in a cross section view, a part of a fourth example of embodiment of a cooling plate according to the invention, and - figure 6 illustrates schematically, in a cross section view, a part of a fifth example of embodiment of a cooling plate according to the invention,

[0012] The invention aims, notably, at proposing a cooling plate (or stave) 1 that can be used in a blast furnace and presenting an increased wear resistance.

[0013] An example of embodiment of a cooling plate (or stave) 1 according to the invention is illustrated in figure 1 . Such a cooling plate (or stave) 1 is intended to be mounted on an inner wall of a blast furnace. [0014] As illustrated, a cooling plate (or stave) 1 according to the invention comprises a copper body 2 having an inner (or hot) face 3 comprising several ribs 4-j parallel therebetween. These ribs 4-j have two first extremities 6 opposite therebetween and are separated by grooves 5 having two second extremities 7 opposite therebetween. Once the cooling plate 1 is mounted on the blast furnace inner wall, its ribs 4-j and grooves 5 are arranged horizontally. In this case the copper body 2 comprises an outer face 14 that is opposite to its inner face 3 and fixed to the inner wall blast furnace. So, the inner face 3 is the body face that can be in contact with the very hot material and gas present inside the blast furnace. [0015] For instance, and as illustrated in figures 3 to 6, the grooves 5 may have a dovetail cross-section in order to optimize anchorage of a process generated accretion layer 15 when they do not comprise an optional multilayer protrusion 10 (described below)_But _T the-Fibs-4-j-and-grooves ^~ 5-may have other cross^ection shapes. Thus, and as illustrated in figures 1 and 2, they may have a rectangular cross-section, for instance. [0016] More, and as illustrated in the non-limiting example of figure 1 , the inner face 3 of the copper body 2 may comprise ribs 4-j having at least two different heights hi and h2. This option allows optimizing anchorage of refractory bricks 15. In the example of figure 1 , first ribs 4-1 (j = 1 ) have a first height hi and second ribs 4-2 (j = 2), defined between first ribs 4-1 , have a second height h2 that is smaller than the first height hi . But, as illustrated in the other examples of embodiment of figures 2 to 6, the copper body 2 may comprise ribs 4-1 having the same height. [0017] Still more, and as illustrated in figures 2 and 3, the copper body 2 comprises preferably internal channels 16 in which a cooling fluid flows.

[0018] As illustrated in figures 1 to 6, at least one of the ribs 4-j comprises at least one housing 8 located between its first extremities 6 and comprising at least one insert 9 made of a wear resistant material that increases locally the wear resistance of the rib 4-j.

[0019] Thanks to the rib inserts 9, the wear resistance of the ribs 4-j can be appreciably increased which allows avoiding an early erosion of their material (i.e. copper or copper alloy).

[0020] In the non-limiting example of figure 1 , only the first ribs 4-1 comprise at least one housing 8 comprising at least one insert 9. This is due to the fact that the second height h2 of the second ribs 4-2 is too small to allow definition of the housing(s) 8.

For instance, the wear resistant material of the insert 9 may be a metal or a ceramic. This wear resistant metal may be, for instance, a steel or cast iron, preferably a refractory grade (for example a heat-resistant casting steel such as GX40CrSi13 in which the chemical composition comprises, the contents being expressed as weight percentages : 0,3% < C < 0,5%, 1 % < Si < 2,5%, 12 < Cr < 14%, Mn < 1 %, Ni < 1 %, P≤ 0,04%, S < 0,03% and Mo < 0,5% ) or a wear- resistant steel able to work at high temperatures. The wear resistant ceramic may be, for instance, an silicon carbide (SiC), extruded silicon carbide (higher thermal conductivity) or other refractory material with good resistance to spalling and high hardness.

[0021 ] When at least one rib 4-j comprises at least one housing 8, each housing 8 may be a slot comprising at least one insert 9. This is notably the case in the examples illustrated in figures 1 to 3. It is important to notice that a rib 4-j may comprise only one slot 8 extending between its first extremities 6, possibly from one first extremity 6 to the opposite one (as illustrated), or at least two slots 8 defined between its first extremities 6, preferably along a same axis. Moreover each slot 8 may comprise one or more inserts 9 placed one after the other. Each slot 8 may be defined by machining, for instance by means of a drill bit.

[0022] In a variant, not illustrated, each housing 8 may be a threaded hole in which a bolt, defining an insert 9, is screwed. It is important to notice that a rib 4-j may comprise only one threaded hole 8 defined between its first extremities 6, or at least two threaded holes 8 defined between its first extremities 6, preferably along a same axis. Each threaded hole 8 may be defined by machining, for instance by means of a drill bit. Preferably, the holes 8, and therefore the bolts 9, are installed in front of cooling channels 16 to protect the bolts 9 and reduce their number. In this case, bolts 9 are not only well connected with copper (through the threads), but also well cooled.

[0023] As illustrated in figures 4 to 6, in addition, at least one of the grooves 5 of the copper body 2 may comprise at least a part of a multilayer protrusion 10 extending between its second extremities 7 and comprising at least one layer 12 made of the wear resistant material that increases locally the wear resistance of the neighboring ribs 4-j.

[0024] So, in this last option one or several ribs 4-j comprise(s) at least one housing 8 located between its/their first extremities 6 and comprising at least one insert 9 made of a wear resistant material, and one or several grooves 5 comprise(s) at least a part of a multilayer protrusion 10 extending between its second extremities 7 and comprising at least one layer 12 made of a wear resistant material. [0025] Thanks to the multilayer protrusions 10 (located into grooves 5), the speed and pressure exerted by the descending burden on the stave are appreciably decreased, which allows avoiding an early erosion of their material (i.e. copper or copper alloy) and of the stave body. In other words, the protrusions allows generating an area of low material movement to minimize wear.

[0026] The wear resistant material of each layer 12 is preferably the same as the one of an insert 9. So, it may be a metal or a ceramic as described above for the insert 9.

[0027] When at least one groove 5 comprises at least a part of a multilayer protrusion 10, the latter 10 may comprise a first layer 1 1 made of a material having a high thermal conductivity, and a second layer 12 made of the wear resistant material and set on top of this first layer 1 1. This is notably the case in the examples illustrated in figures 4 to 6. Contrary to the previous embodiment (illustrated in figures 1 to 3), this embodiment allows an adaptation of a conventional cooling plate without any machining phase.

[0028] The first layer 1 1 having a high thermal conductivity is laid in the lowest position of the multilayer protrusion 10 to act as a heat shield, because the thermal load is coming mainly from hot gas streams flowing upwards. For instance, the material of this first layer 1 1 may be a high conductivity metal copper or a copper alloy. The second layer 12 is made of the wear resistant material and laid on top of the first layer 1 1 to protect it from an early erosion. As mentioned before, this second layer 12 can be made of wear-resistant steel, cast iron or ceramic.

[0029] Also for instance, and as illustrated in figures 4 and 5, each multilayer protrusion 10 may be associated to a single groove 5. In other word a part of each multilayer protrusion 10 is located into a single groove 5 while the remaining part of this multilayer protrusion 10 extends beyond this single groove 5.

[0030] In this case, each multilayer protrusion 10 may further comprise a third layer 13 sandwiched between the first 1 1 and second 12 layers and made of a ceramic material having a very high hardness intended for increasing the wear resistance of the whole protusion.

[0031 ] In the example of figure 4, each third layer 13 is in contact with a part of the inner face 3 that delimitates the base of its associated groove 5, while in the example of figure 5, each third layer 13 is separated by a protruding part of the underlying first layer 1 1 from the part of the inner face 3 that delimitates the base of its associated groove 5. The alternative shown in figure 4 can be installed on the stave from the front side, while the alternative displayed in figure 5 can only be installed sideways inside the groove. The advantage of this latter variant is the higher stability of the set in case the brittle ceramic piece would be broken in pieces.

[0032] For instance, each third layer 13 may be made of a high-hardness ceramic such as SiC or extruded SiC. A ceramic can be used here because it is sandwiched and therefore protected from impact of falling material and independent of the cooling plate bending that can be induced by a thermal expansion. [0033] In a variant of embodiment, illustrated in figure 6, the first 1 1 and second 12 layers of each multilayer protrusion 10 may be respectively associated to two neighboring grooves 5. In other words, a part of the first layer 1 1 of a multilayer protrusion 10 is located into a first groove 5, while the remaining part of this first layer 1 1 extends beyond this first groove 5, and a part of the second layer 12 of this multilayer protrusion 10 is located into a second groove 5 located near the first groove 5, while the remaining part of this second layer 12 extends beyond this second groove 5. So, the first layer 1 1 in the lower part takes the heat load towards the copper body 2, while the second layer 12 on top protects the associated first layer 1 1 from wear.

[0034] In this case, and as illustrated in the non-limiting example of figure 6, the first layer 1 1 of each multilayer protrusion 10 may comprise a slot 17 extending between the second extremities 7 and comprising an other insert 18. This other insert 18, embedded in a first layer 1 1 , is made of a material having a hardness intended for increasing hardness of this first layer 1 1 . For instance, and as illustrated in the non-limiting example of figure 6, the face of the first layer 1 1 , in which is defined (or machined) the slot 17, may be inclined to send the gas outwards and also to help the burden flow smoothly into the "pockets" that are built with the profusions 10.

[0035] Also for instance, and as illustrated in figure 6, each other slot 17, and therefore the associated other insert 18, may have a dovetail cross-section. [0036] Also for instance, each other insert 18 may be made of a ceramic such as SiC or a steel (wear-resistant, heat-resistant of a combination of both). Other implementations to increase the hardness of the layer 1 1 can be used. For exemple, each slot 17 may be a threaded hole in which a bolt, defining an insert 18, is screwed .

[0037] It is important to note that in the case where the cooling plate 1 comprises also multilayer protrusions 10, the grooves 5 in which these multilayer protrusions 10 are located may depend on the shape and/or dimensions of the blast furnace. For instance, in the example illustrated in figures 4 and 5 a multilayer protrusion 0 may be located every three grooves 5. But, in other examples a multilayer protrusion 10 may be located every two or four or even five grooves 5.

[0038] As illustrated in figure 4 to 6, in the case where the cooling plate 1 comprises multilayer protrusions 10, the ribs 4-j delimiting the grooves 5 comprising these multilayer protrusions 10 or embedded into multilayer protrusions 10 do not really need to comprise housing(s) 8 comprising insert(s) 9, because they are already protected by these multilayer protrusions 10. So, preferably only ribs 4-j not located in the vicinity of a multilayer protrusion 10 comprise housing(s) 8 comprising insert(s) 9.