EP3765641A1

EP3765641A1 - Stave protection system

Info

Publication number: EP3765641A1
Application number: EP19709512.8A
Authority: EP
Inventors: Ian James Mcdonald; Christopher Sharpe
Original assignee: Primetals Technologies Ltd
Current assignee: Primetals Technologies Ltd
Priority date: 2018-03-15
Filing date: 2019-03-13
Publication date: 2021-01-20
Anticipated expiration: 2039-03-13
Also published as: KR20200130294A; EP3540080A1; JP2023014120A; CN210796514U; RU2020127871A; RU2020127871A3; CN110273035A; JP7486876B2; EP3765641B1; WO2019175244A1; JP2021518521A

Abstract

A stave protection system for a metallurgical furnace comprises: a stave comprising a front face having an X direction and a Y direction which is perpendicular to the X direction such as to define an X-Y plane, the front face comprising rows of grooves which extend in the X direction; and inserts which are slidingly received by the grooves, the inserts so received by each respective groove being spaced apart from each other along the groove, the centres of the inserts which are received by one of the grooves being offset in each of the X and Y directions from the centres of the inserts which are received by an adjacent groove, each of the inserts projecting from the front face of the stave and comprising flow guiding surfaces which are inclined with respect to each of the X and Y directions in the X-Y plane, such that in use the offsets of the inserts in each of the X and Y directions and the inclined flow guiding surfaces cause a flow of furnace burden material, under gravity, to flow in a direction having a component in each of the X and Y directions, so as to distribute the burden material between the inserts over the front face of the stave and/or trap the burden material between the inserts.

Description

STAVE PROTECTION SYSTEM

BACKGROUND OF THE INVENTION

The present invention relates to a stave protection system for a metallurgical furnace, for example a blast furnace.

A conventional blast furnace comprises several sections and components including a stack, belly, bosh, tuyere, hearth and taphole. The internal shell of the blast furnace may be protected with water-cooled cooling plates, called staves, which protect the shell from overheating during the reduction process taking place within the furnace. Modern staves are typically constructed from copper or copper alloy although other materials may be used, for example steel or cast iron.

The staves can be susceptible to abrasive wear from the solid raw materials charged into the furnace as they make their descent through the furnace. In some circumstances the severity of the wear has resulted in the requirement to replace the staves before their planned service life has completed. This is costly due to furnace downtime. It is therefore important to design staves to resist wear so as to prolong service life.

It is known that wear of the staves is reduced by forming a frozen accretion layer on the front face of the stave during operation. To this end the stave has a machined front face, or hot face, comprising ribs and grooves which hold the accretion onto the stave. A portion of an exemplary copper stave of this type is shown in Figure 1.

A refinement of this concept has been the addition of a front-face protective material or cladding, which is harder than the copper base material but which still allows a protective accretion layer to form by freezing on the face. This has been achieved using a combination of silicon carbide and graphite bricks, as illustrated in Figure 2 which shows a copper stave and a cross-section thereof. WO2009/147192 describes a stave having a front face comprising ribs and grooves which form anchorage means for anchoring a refractory brick lining, a refractory guniting or a process generated accretion layer to the face. Metal inserts are provided in the grooves, as is illustrated schematically in Figure 3. The metal inserts cover the sidewalls of the ribs to protect the ribs from erosion. Possible problems with this solution however are that the metal inserts may be prone to distortion and/or buckling and by using a less conductive material than that of the stave body (when copper) there is a reduced thermal performance of the stave which can impact the freezing of a protective accretion layer.

Referring now to Figure 4, it has been proposed to place a plurality of projecting rectangular blocks in each of the grooves of the face of the stave, the blocks being spaced from one another along the length of the groove. The blocks may comprise silicon carbide or some other hard material, thereby providing the face of the stave with a protective cladding. The blocks are separated from each other by shorter spacer inserts. The inserts may protect the face of the stave in the regions between the blocks. As is shown in Figure 4, the blocks are preferably staggered between the grooves such as to provide a chequer pattern on the face of the stave.

Thus the existing solutions for reducing the rate of stave wear include:

i) installing a refractory/ceramic wear lining in or in front of the stave; ii) installing ledges at the front face of the stave to promote thicker accretion build-up; and

iii) installing cladding within the machined shapes at the front face.

While these solutions have resulted in some improvements, there remains a need for new technologies which can offer a reduction in the rate of stave wear in order to extend service life and reduce furnace downtime.

DE 73 31 936 U relates to a cooling element for furnace linings. SUMMARY OF THE INVENTION

According to an aspect of the invention there is provided a stave protection system for a metallurgical furnace, comprising: a stave comprising a front face having an X direction and a Y direction which is perpendicular to the X direction such as to define an X-Y plane, the front face comprising rows of grooves which extend in the X direction; and inserts which are slidingly received by the grooves, the inserts so received by each respective groove being spaced apart from each other along the groove, the centres of the inserts which are received by one of the grooves being offset in each of the X and Y directions from the centres of the inserts which are received by an adjacent groove, each of the inserts projecting from the front face of the stave and comprising flow guiding surfaces which are inclined with respect to each of the X and Y directions in the X-Y plane, such that in use the offsets of the inserts in each of the X and Y directions and the inclined flow guiding surfaces cause a flow of furnace burden material, under gravity, to flow in a direction having a component in each of the X and Y directions, so as to distribute the burden material between the inserts over the front face of the stave and/or trap the burden material between the inserts.

As will be described in more detail later herein, the inserts provide a cladding for the front face (or hot face) of the stave which encourages a protective layer of burden material to form on the front face when the stave is used in a furnace. The offsetting of the inserts and the provision of inclined flow guiding surfaces advantageously causes the burden material to be distributed over the face of the stave simultaneously in the X and Y directions.

The configuration and arrangement of the inserts (e.g. their offsetting and geometrical shape) encourages the burden material to be trapped by or between the inserts as the burden material flows under gravity. Trapping of burden material may occur when burden material is passed over the inclined flow guiding surfaces in each of the X and Y directions.

It may be that the burden material becomes trapped, by or between the inserts, having first been distributed generally over the front face of the stave as described above. Thus, in use the offsets of the inserts in each of the X and Y directions and the inclined flow guiding surfaces cause a flow of furnace burden material, under gravity, to flow in a direction having a component in each of the X and Y directions, so as to distribute the burden material between the inserts over the front face of the stave and to trap the burden material between the inserts.

It may be that the burden material becomes trapped, by or between the inserts, without first having been distributed generally over the front face of the stave. For example, burden material may be trapped at a local region of the front face, without having first been spread across all or even a major portion of the front face. Thus, in use the offsets of the inserts in each of the X and Y directions and the inclined flow guiding surfaces cause a flow of furnace burden material, under gravity, to flow in a direction having a component in each of the X and Y directions, so as to trap the burden material between the inserts at the front face of the stave.

Thus the inserts function to distribute burden material over the front face of the stave and subsequently to trap the burden material between them, or simply to trap the burden material between them without prior distribution generally over the front face. Whether or not the burden material tends to be distributed over the front face may depend on flow conditions, including for example the volume and weight of the burden material, and its flow rate, temperature and viscosity.

Furthermore, burden material can directly enter the spaces between the inserts from a flow direction which is substantially perpendicular to the X-Y plane. Such burden material can be trapped by or between the inserts, without necessarily first passing over the inclined flow guiding surfaces in each of the X and Y directions.

As used herein, “burden material” refers to one or both of (i) iron-bearing materials in the blast furnace, for example iron-ore or iron-ore pellets, and (ii) blast furnace slag, i.e. slag which is formed when iron-ore or iron pellets, coke and a flux (e.g. limestone or dolomite) are melted together in the blast furnace and then solidified.

The offset in the X direction may be such that an imaginary line, which extends in the Y direction, intersects flow guiding surfaces of the inserts which are received by the one of the grooves and flow guiding surfaces of the inserts which are received by the adjacent groove.

The offset in the Y direction may be such that an imaginary line, which extends in the X direction, intersects flow guiding surfaces of the inserts which are received by the one of the grooves and flow guiding surfaces of the inserts which are received by the adjacent groove.

The offset in the X direction may be such that an imaginary line, which extends in the Y direction, intersects flow guiding surfaces of the inserts which are received by the one of the grooves and flow guiding surfaces of the inserts which are received by the adjacent groove; and the offset in the Y direction may be such that an imaginary line, which extends in the X direction, intersects flow guiding surfaces of the inserts which are received by the one of the grooves and flow guiding surfaces of the inserts which are received by the adjacent groove.

The offset in the X direction may be such that: the distance in the X direction, between the centres of the inserts which are received by the one of the grooves, is D; and the distance in the X direction, between the centres of the inserts which are received by the adjacent groove and the centres of the inserts which are received by the one of the grooves, is D/2.

Each of the flow guiding surfaces may be perpendicular to the front face of the stave.

Each insert may comprise a projection part which includes the flow guiding surfaces and an attachment part which is received by the respective groove. The insert may be of unitary construction such that the projection part and the attachment part are integral. Alternatively the insert may be of non-unitary construction such that the projection part and the attachment part are discrete elements.

The projection part may be polyhedral and sides of the projection part may comprise the flow guiding surfaces. The projection part may be hexagonal and each one of four of the six sides of the projection part may comprise a respective one of the inclined flow guiding surfaces. The other two sides of the hexagonal projection part may each extend in the Y direction. Alternatively the other two sides of the hexagonal projection part may each extend in the X direction.

The projection part may comprise a recess.

The inserts which are received by each respective groove may be spaced apart from each other along the groove by spacers which are slidingly received in the groove. At least one of the spacers may be an integral part of at least one of the inserts. At least one of the spacers may be a discrete element.

The spacers may be configured to cover the surfaces of the respective grooves between the inserts. Alternatively the spacers may be configured to expose the surfaces of the respective grooves between the inserts.

The stave may comprise a metallic material. The metallic material may comprise copper, copper alloy, steel or cast iron.

At least one of the inserts may comprise a metallic material. The metallic material may comprise copper, copper alloy, steel or cast iron. At least one of the inserts may comprise an abrasion resistant refractory material. The abrasion resistant refractory material may comprise silicon carbide or alumina.

At least one of the spacers may comprise a metallic material. The metallic material may comprise copper, copper alloy, steel or cast iron. At least one of the spacers may comprise an abrasion resistant refractory material. The abrasion resistant refractory material may comprise silicon carbide or alumina. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example, with reference to the accompanying figures in which:

Figure 1 shows a portion of a conventional stave for a furnace;

Figure 2 shows a conventional stave comprising silicon carbide and graphite bricks;

Figure 3 shows a portion of a conventional stave comprising metal inserts;

Figure 4 shows a portion of a conventional stave comprising metal inserts and projecting rectangular blocks;

Figures 5a and 5b respectively show an insert and a spacer according to an embodiment of the invention;

Figure 6a shows a portion of a stave for use in an embodiment of the invention; Figures 6b and 6c show a plurality of the inserts and a plurality of the spacers installed in the stave of Figure 6a according to an embodiment of the invention; Figure 7 shows flow channels which are formed between exemplary inserts; and Figure 8 shows an arrangement of the inserts in a stave according to another embodiment of the invention.

DETAILED DISCUSSION

Referring to Figure 5a, an insert 100 comprises a projection part 102 and an attachment part 104. In this exemplary embodiment the insert 100 is of unitary construction, so that each of the projection part 102 and the attachment part 104 is a portion of the single-piece insert 100. In this embodiment, the insert 100 comprises silicon carbide. Alternatively the insert 100 may comprise alumina, copper, copper alloy, steel, cast iron, or other suitable ceramic, metal, or metal alloy.

The projection part 102 comprises a front face 102a and a rear face 102b which are connected to each other by a peripheral outer edge having six faces 102c1 -6 which form a regular hexagon. In other words, the projection part 102 is a hexagonal prism. Vertices 102ci-vi are formed at the intersections of the faces 102c1 -6 (only 102ci is labelled in the figure). A circular recess 102d extends into the body of the projection part 102 from the front face 102a and comprises a floor 102d 1 (not shown) and a peripheral wall 102d2. Accordingly the circular recess 102d forms a blind hole or bore in the body of the projection part 102. The bore has a central axis C, which is coincident with the geometric centre of the insert 100.

The attachment part 104 extends rearwardly of the projection part 102. More particularly, each one of pair of side faces 104a, 104b of the attachment part 104 extends rearwardly from a respective one of opposite faces 102c2, 102c5 of the peripheral outer edge of the projection part 102. The rear ends of the side faces 104a, 104b are connected to each other by a rear face 104c of the attachment part 104 which lies parallel with the front and rear faces 102a, 102b of the projection part 102.

An upper face 104d of the attachment part 104 extends laterally between upper edges of the side faces 104a, 104b and also forwardly to the rear face 102b of the projection part 102. Similarly a lower face 104e of the attachment part 104 extends laterally between lower edges of the side faces 104a, 104b and also forwardly to the rear face 102b of the projection part 102.

The upper and lower faces 104d, 104e of the attachment part 104 are inclined or sloped with respect to the central axis C such as to form a convergent taper from the rear face 104c of the attachment part 104 to the rear face 102b of the projection part 102. In other words, the sloping upper and lower faces 104d, 104e provide the attachment part 104 with a wedge-shaped profile, the thickest section of the wedge being located at the rear face 104c of the attachment part 104 and the thinnest section of the wedge being located at the rear face 102b of the projection part 102.

In another embodiment the projection part 102 and the attachment part 104 are discrete elements which can be permanently or removably attached to each other in order to form the insert 100. In such an embodiment, each of the projection part 102 and the attachment part 104 may comprise any of silicon carbide, alumina, copper, copper alloy, steel, cast iron, or other suitable ceramic, metal or metal alloy.

Turning now to Figure 5b, a spacer 200 comprises rectangular front and rear faces 200a, 200b which are connected by four sides 200c-f. In this embodiment, the spacer 200 comprises two longer sides 200c, 200d and two shorter sides 200e, 200f. Alternatively the front and rear faces 200a, 200b may be square such that the spacer 200 comprises four sides of equal length.

Each of the longer sides 200c, 200d is sloped such that the spacer 200 presents a wedge shape when viewed in profile, the thickest section of the wedge being located at the rear face 200b and the thinnest section of the wedge being located at the front face 200b.

In this embodiment, the spacer 200 comprises copper alloy. Alternatively the spacer 200 may comprise silicon carbide, alumina, copper, copper alloy, steel, cast iron, or other suitable ceramic, metal, or metal alloy.

Referring now to Figure 6a, a rectangular cooling plate or stave 300 comprises a front face (or hot face) 302, a rear face 304, and edges 306a-d (the bottom edge 306d is not shown in Figure 6a). The stave 300 is intended to be one of a plurality of similar staves for use in a blast furnace.

In this exemplary embodiment the stave 300 has a width (in the X direction in the sense of Figure 6a) of about 1.0 m, a height (in the Y direction in the sense of Figure 6a) of about 1.5 m, and a maximum thickness or depth (in the Z direction in the sense of Figure 6a) of about 120 mm. It will be understood that the X, Y, Z denotion of width, height and depth respectively is for convenience of reference only and is not limiting for the claimed invention.

The interior of the stave 300 comprises water-cooling passages 310. The stave 300 body is otherwise generally solid. In this embodiment the stave 300 is constructed from copper alloy. Alternative materials include, but are not limited to, copper, steel, and cast iron.

The front of the stave 300 comprises a plurality of similar grooves 312 which are arranged in rows and are separated from one another by projecting ribs 314. In this exemplary embodiment, there are 12 grooves 312 and 13 ribs 314 (only some of which are visible in Figure 6a, which shows only a portion of the stave 300). Each groove 310 extends across the entirety of the width of the stave 300 such as to have an open end at each of the side edges 306a, 306c of the stave 300. Each one of the grooves 310 has a long axis L which extends between the ends of the groove (in the X direction in the sense of Figure 6a).

In this embodiment, the grooves 312 are formed by machining. Alternatively the grooves 312 may be formed by casting.

Each one of the grooves 312 comprises a flat base or floor 312a. Each one of the grooves 312 further comprises a pair of opposing walls 312b. Each one of the opposing walls 312b is a surface of one of the two adjacent ribs 314 which define the groove 312. Each one of the ribs 314 includes a flat face 314a. The flat faces 314a are parallel with the floors 312a of the grooves 312. The front face 302 of the stave 300 may therefore be regarded as comprising two parts, that is: a front-most part which comprises the flat faces 314a of the projecting ribs 314 and a recessed part which comprises the flat floors 312a of the grooves 312.

Each one of the two opposing walls 312b of each one of the grooves 312 is inclined, such as to provide each one of the grooves 312 with a convergent taper from the floor 312a of the groove 312 to the respective flat faces 314a of the ribs 314 which define the groove 312. Thus each one of the grooves 312 presents a wedge-shaped profile (when viewed from a side edge 306a, 306c of the stave 300), the thickest section of the wedge being located at the floor 312a of the groove 312 and the thinnest section of the wedge being located at the flat faces 314a of the ribs 314. The angle of inclination of the opposing walls 312b is configured to complement the sloped upper and lower faces 104d, 104e of the attachment part 104 of the insert 100 and also the sloped longer sides 200c, 200d of the spacer 200.

Furthermore the depth of each one of the grooves 312 (that is to say the distance between the faces 314a of the two adjacent ribs 314 which define the groove 312, and the floor 312a of the groove 312), is approximately equal to each of the thickness of the spacer 200 (that is to say the distance between the front and rear faces 200a, 200b of the spacer 200) and the depth of the attachment part 104 of the insert 100 (that is to say the distance between the rear face 104c of the attachment part and the rear face 102b of the projection part 102 of the insert 100).

Turning now also to Figure 6b, inserts 100 and spacers 200 as described herein above are installed in the grooves 312 of the stave 300 such as to provide the stave 300 with a protective cladding. In combination the stave 300, inserts 100 and spacers 200 comprise a stave protection system.

The installation of the inserts 100 and spacers 200 in the grooves 312 will now be explained with particular reference to Figures 6b and 6c. For brevity, the operation will be presented in terms of only one pair of the grooves 312a, 312b of the stave; however it will be understood that the principle of installation of inserts 100 and spacers 200 will be the same for other pairs of the grooves 312.

The stave 100 is most conveniently first arranged in an upright, vertical position for the purpose of installation of the inserts 100 and spacers 200. That is, the front face 302 will lie in the vertical plane. It will be understood that in this position the long axis L of each one of the grooves 312 will extend horizontally, so as to be parallel with the floor and perpendicular to the vertical direction.

A first spacer 200 is offered up to the left-hand side edge 306a of the stave 300, alongside the first exemplary groove 312L The orientation of the first spacer 200 is such that its longer sides 200c, 200d lie parallel with the long axis L of the first groove 312i, its front face 200a looking forward and its rear face 200b looking rearward of the stave 300. The first spacer 200 is then moved rightward and is slidingly inserted into the open left-hand end of the first groove 312i, such that the rear face 200b of the first spacer 200 contacts the floor 312a of the first groove 312i and the longer sides 200c, 200d of the first spacer 200 contact the respective opposing walls 312b of the first groove 312L Thus the first spacer 200 is slidingly received by the first groove 312i. It will be understood that the dimensions, of the first spacer 200 and the first groove 312i, are such that the first spacer 200 fits snugly in the first groove 312i but has sufficient freedom to slide along the first groove 312i under a force which is applied by an operator.

The first spacer 200 is slid further rightward in and along the first groove 312i, the lateral travel of the first spacer 200 across the stave 300 being guided by the floor 312a and opposing walls 312b of the first groove 312i. The first spacer 200 is brought to rest at the right-hand end of the first groove 312i, such that the right-hand shorter side 200f of the first spacer 200 is flush with the right-hand side edge 306c (not shown in Figures 6b and 6c) of the stave 300.

In this position the rear face 200b of the first spacer 200 is in abutment with the floor 312a of the first groove 312i and each one of the longer sides 200c, 200d of the first spacer 200 is in abutment with one of the opposing walls 312b of the first groove 312L Furthermore the front face 200a of the first spacer 200 is flush with the flat faces 314a of the adjacent ribs 314. Due to the opposite taper, of the wedge-shaped longer sides 200c, 200d of the first spacer 200 and the opposing walls 312b of the first groove 312i, the first spacer 200 is prevented from falling from or being pulled out of the front face 302 of the stave 300. That is, the opposite taper provides a strong“dovetail” joint which resists displacement of the first spacer 200 forwardly and away from the front face 102 (i.e. in the Z direction in the sense of Figure 6b). Thus the first spacer 200 is securely retained or attached at the front face 302 of the stave 300. Next, a first insert 100 is offered up to the left-hand side edge 306a of the stave 300, alongside the first exemplary groove 312L The orientation of the first insert 100 is such that the upper and lower faces 104d, 104e of the attachment part 104 lie parallel with the long axis L of the first groove 312i, the front face 102a of the projection part 102 looking forward and the rear face 104c of the attachment part 104 looking rearward of the stave 300.

The first insert 100 is then moved rightward and the attachment part 104 is slidingly inserted into the open left-hand end of the first groove 312i, such that the rear face 104c of the attachment part 104 contacts the floor 312a of the first groove 312i and the upper and lower faces 104d, 104e of the attachment part 104 contact the respective opposing walls 312b of the first groove 312L Thus the first insert 100 is slidingly received by the first groove 312L It will be understood that the dimensions, of the attachment part 104 of the first insert 100 and the first groove 312i, are such that the attachment part 104 fits snugly in the first groove 312i but has sufficient freedom to slide along the first groove 312i under a force which is applied by an operator.

The first insert 100 is slid further rightward in and along the first groove 312i, the lateral travel of the first insert 100 across the stave 300 being guided by the floor 312a and opposing walls 312b of the first groove 312i. The first insert 100 is brought to rest at the left-hand end of the first spacer 200, such that the right- hand side face 104a of the attachment part 104 is in contact with the left-hand shorter side 200e of the first spacer 200.

In this position the rear face 104c of the attachment part 104 is in abutment with the floor 312a of the first groove 312i and each one of the upper and lower faces 104d, 104e of the attachment part 104 is in abutment with one of the opposing walls 312b of the first groove 312L Furthermore the projection part 102 of the first insert 100 protrudes (in the Z direction in the sense of Figure 6b) from the flat faces 314a of the adjacent ribs 314.

Due to the opposite taper, of the wedge-shaped upper and lower faces 104d, 104e of the attachment part 104 and the opposing walls 312b of the first groove 312i, the first insert 100 is prevented from falling from or being pulled out of the front face 302 of the stave 300. That is, the opposite taper provides a strong “dovetail” joint which resists displacement of the first insert 100 forwardly and away from the front face 102 (in the Z direction in the sense of Figure 6b). Thus the first insert 100 is securely retained or attached at the front face 302 of the stave 300.

Next, a second spacer 200 is provided which is generally similar to the first spacer 200 as described herein above, except that the length of the second spacer 200 is less than the length of the first spacer 200. That is, the first spacer 200 is a full-length spacer while the second spacer 200 is a short spacer. The combination of full-length and short spacers results in an offset between the geometric centres of the inserts 100 of the first and second exemplary grooves 312a, 312b, as will be further explained later herein.

The second spacer 200 is offered up to the left-hand side edge 306a of the stave 300, alongside the first exemplary groove 312i, in the same orientation described herein above with respect to the first spacer 200. The second spacer 200 is installed in the same way as the first spacer 200, except that, having been slid rightward along the first groove 312i, the second spacer 200 is brought to rest such that the right-hand shorter side 200f of the second spacer 200 is in contact with the left-hand side face 104b of the attachment part 104 of the first insert 100. Thus the second spacer 200 is securely retained or attached at the front face 302 of the stave 300 in the same manner as the first spacer 200.

Next, a second insert 100 is provided which is similar to the first insert 100 as described herein above. The second insert 100 is offered up to the left-hand side edge 306a of the stave 300, alongside the first groove 312i, in the same orientation described herein above with respect to the first insert 100. The second insert 100 is installed in the same way as the first insert 100, except that, having been slid rightward along the first groove 312i, the second insert 100 is brought to rest such that the right-hand side face 104a of the attachment part 104 of the second insert 100 is in contact with the left-hand shorter side 200e of the second spacer 200. Thus the second insert 100 is securely retained or attached at the front face 302 of the stave 300 in the same manner as the first insert 100.

Further short spacers 200 and inserts 100 are alternately installed until the desired number of inserts 100 has been provided in the first groove 312L In this embodiment, four inserts 100 are secured in the first groove 312i.

The left-most spacer 200 which is fitted lastly in the first groove 312i is a full- length spacer. Furthermore, the right-hand shorter side 200f of the left-most spacer 200 is in contact with the left-hand side face 104b of the attachment part 104 of the left-most insert 100, while the left-hand shorter side 200e of the left most spacer 200 is flush with the left-hand side edge 306a of the stave 300.

Next comes the installation of spacers 200 and inserts 100 in the second groove 312N, which is immediately adjacent to the first groove 312i. That is, the first and second exemplary grooves 312i, 312N share a common rib 314 which separates the two grooves 312i, 312N.

A first spacer 200, which is a short spacer of the type described herein above, is offered up to the left-hand side edge 306a of the stave 300, alongside the second exemplary groove 312N. The first spacer 200 is installed in the second groove 312N, in the manner described herein above with respect to the first groove 312i.

Next, a first insert 100, which is similar to the inserts 100 which are fitted in the first groove 312i, is offered up to the left-hand side edge 306a of the stave 300, alongside the second groove 312N. The first insert 100 is installed in the second groove 312N, in the manner described herein above with respect to the first groove 312i.

Further short spacers 200 and inserts 100 are alternately installed until the desired number of inserts 100 has been provided in the second groove 312ii. Since no full-length spacers 200 are fitted in the second groove 312N, the number of inserts 100 in the second groove 312N is one less than the number of inserts 100 in the first groove 312L Thus in this embodiment, three inserts 100 are secured in the second groove 312N.

In this exemplary embodiment the stave 300 comprises a total of 12 grooves 312 and it will be understood that pairs of the grooves 312 are fitted with spacers 200 and inserts 100 in the manner described herein above.

While in the described exemplary embodiment the spacers 200 and inserts 100 are inserted at the left-hand side edge 306a of the stave 300 and slid rightward, it will be understood that they may be equally well inserted at the right-hand side edge 306c of the stave 300 and slid leftward.

Once installed, the spacers 200 and inserts 1 1 may be prevented from sliding laterally out of the grooves 312 by end caps (not shown in the figures) which are attached to the ends of the grooves 312 at the edges 306a, 306c of the stave 300. Alternatively, at least the spacers 200 which are proximate to the edges 306a, 306c of the stave 300 may be fixed to the stave 300, for example by screws which engage with threaded holes which are provided in the body of the stave 300, or by welding to the stave 300. Any or all of the spacers 200 and inserts 100 may be attached to the stave 300 by such means.

The projection parts 102 of the inserts 100 which are secured in the grooves 312 will now be described in more detail with particular reference to Figure 6c.

It will be recalled that the projection part 102 of each insert 100 comprises a peripheral outer edge having six faces 102c1 -6 which form a regular hexagon, vertices 102ci-vi being formed at the intersections of the faces 102c1 -6. In this exemplary embodiment, the six faces 102c1 -6 lie perpendicular to the front face 302 of the stave 300 (in the Z direction in the sense of Figure 6c). The six faces 102c1 -6 provide flow guiding surfaces, as will be further explained later herein.

In this exemplary embodiment, four faces 102c1 , 102c3, 102c4, 102c6 of the six faces 102c1 -6 (or flow guiding surfaces) of each one of the installed inserts 100 are each sloped or inclined, with respect both to the long axes L of the grooves 312 (which extend in the X direction in the sense of Figure 6c) and to a direction which is perpendicular to the long axes L of the grooves 312 (the Y direction in the sense of Figure 6c). In other words, each one of these four faces 102c1 , 102c3, 102c4, 102c6 lies at a non-zero angle from each of the long axes L of the grooves 312 and the direction which is perpendicular to the long axes L of the grooves 312. Put differently, the four faces 102c1 , 102c3, 102c4, 102c6 each lie at an angle which is between the direction of the long axes L of the grooves 312 and the direction which is perpendicular to the long axes L of the grooves 312.

Also in this embodiment, the other two faces 102c2, 102c5 of the projection part 102 extend in the direction which is perpendicular to the long axes L of the grooves 312 (the Y direction in the sense of Figure 6c). Accordingly, the front face 102a of the projection part 102 extends between the other two faces 102c2, 102c5 in the direction of the long axes L of the grooves 312 (the X direction in the sense of Figure 6c) and also between opposing vertices 102ci, 102civ in the direction which is perpendicular to the long axes L of the grooves 312 (the Y direction in the sense of Figure 6c).

In an alternative embodiment, the other two faces 102c2, 102c5 of the projection part 102 extend in the direction of the long axes L of the grooves 312 (the X direction in the sense of Figure 6c). Accordingly, in this alternative embodiment, the front face 102a of the projection part 102 extends between the other two faces 102c2, 102c5 in the direction which is perpendicular to the long axes L of the grooves 312 (the Y direction in the sense of Figure 6c) and also between opposing vertices in the direction of the long axes L of the grooves 312 (the X direction in the sense of Figure 6c).

As has been mentioned herein above, the inserts 100 of the first groove 312i and the inserts of the second groove 312N are offset from each other. The offsetting or“staggering” of the inserts 100 will now be described in more detail with continuing reference to Figure 6c.

In this exemplary embodiment, the distance (in the X direction in the sense of Figure 6c), between the geometric centres of neighbouring or immediately- adjacent inserts 100 which are secured in one of the grooves 312, is D, while the distance (in the X direction in the sense of Figure 6c) between the geometric centres of inserts 100 which are secured in a neighbouring or immediately- adjacent groove 312, and the geometric centres of the inserts which are secured in the one of the grooves 312, is half of distance D.

A first line L1 extends in the direction of the long axes L of the grooves 312 (the X direction in the sense of Figure 6c) and a second line L2 extends in the direction which is perpendicular to the long axes L of the grooves 312 (the Y direction in the sense of Figure 6c). It will be understood that the lines L1 and L2 are imaginary lines which are provided merely for the purpose of explanation and which do not form any part of the structure of the described embodiment.

Each of the first and second lines L1 , L2 intersects both of an exemplary pair of inclined faces 102c3, 102c6 (or inclined flow guiding surfaces), one of the inclined faces 102c3 belonging to the projection part 102 of a first insert 100 in a first groove 312 and the other of the inclined faces 102c6 belonging to the projection part 102 of a second insert 100 in a neighbouring or immediately- adjacent groove 312. Thus the inclined faces 102c3, 102c6 are positioned such as to (partially) overlap each other in each of the X and Y directions.

Referring now to Figure 7, the first groove 312i of the stave 300 comprises a first exemplary insert 100Ϊ, the second groove 312ii of the stave 300 comprises second and third exemplary inserts 10Oii, 10Oiii, and a third groove 312iii of the stave 300 (which is immediately adjacent to the second groove 312N) comprises a fourth exemplary insert 10Oiv.

An inclined face of the projection part 102 of the first insert 100Ϊ partially overlaps (in each of the X and Y directions in the sense of Figure 7) with an inclined face of the projection part 102 of the second insert 10Oii such as to define a first channel C1 between the two faces. Similarly another inclined face of the projection part 102 of the first insert 10Oi partially overlaps (in each of the X and Y directions in the sense of Figure 7) with an inclined face of the projection part 102 of the third insert 10Oiii such as to define a second channel C2 between the two faces. Furthermore an inclined face of the projection part 102 of the fourth insert 10Oiv partially overlaps (in each of the X and Y directions in the sense of Figure 7) with an inclined face of the projection part 102 of the second insert 10Oii such as to define a third channel C3 between the two faces. Similarly another inclined face of the projection part 102 of the fourth insert 10Oiv partially overlaps (in each of the X and Y directions in the sense of Figure 7) with an inclined face of the projection part 102 of the third insert 10Oiii such as to define a fourth channel C4 between the two faces.

Also a non-inclined face of the second insert 10Oii overlaps (in the X direction in the sense of Figure 7) with a non-inclined face of the third insert 10Oiii such as to define a fifth channel C5 between the two faces. The first and second channels C1 , C2 converge to lead into the fifth channel C5, which in turn bifurcates or branches into the third and fourth channels C3, C4.

It will be understood that each one of the first to fifth channels comprises a base which is formed by one or both of the front faces 314a of the ribs 314 and the front faces 200a of the spacers 200.

The use of the stave protection system in a blast furnace will now be described.

The panel-like stave 300 is installed at an interior wall of the furnace in an upright fashion. The front (or hot) face 302 faces into the interior of the furnace such that the projection parts 102 of the inserts 100 project from the front face 302 in a substantially horizontal direction.

While the furnace is being used, burden material will pass downwardly through the interior of the furnace. The burden material may include, for example, condensed vapours, solidified slag, and metal.

As is indicated by the arrows in Figure 7, a flow stream F of burden material (not itself shown) will flow downwardly under gravity (in the Y direction in the sense of Figure 7). Portions of the burden material will flow around the first insert 10Oi and through each of the first and second channels C1 , C2. At the point of confluence between the first and second channels C1 , C2 the portions of the flow F will converge and combine with each other so as to flow into the fifth channel C5.

In the fifth channel C5 there is defined a zone T of the front face 302 of the stave 300 which is bounded by three proximate vertices, each of the vertices belonging to a respective one of the second, third and fourth inserts 10Oii, 10Oiii, 10Oiv. Some portion of the burden material will be trapped in the zone T between the three vertices. The trapped burden material will be held in contact with the cooled surface of the front face 302 of the stave 300 (as well as with the flow guiding surfaces of the projection parts 102) and will adhere to the surface so as to form a protective layer. Thus the three vertices provide a highly effective“three-point anchor” for retaining some of the burden material which is directed into the zone T by the first, second and fifth channels C1 , C2, C5.

In this exemplary embodiment, the distance between the vertex of the fourth insert 10Oiv and each of the vertices of the second and third inserts 10Oii, 10Oiii is about 55 mm, since that is the size of a typical particle contained in the burden material.

The remainder of the flow F of the burden material (i.e. that portion of the burden material which is not trapped at the zone T) flows from the fifth channel C5 into the third and fourth channels C3, C4.

It will be understood that the above-described flow pattern of the burden material will occur at and around further, similar groups of inserts 100 on the front face 302 of the stave 300.

The offsetting of the inserts 100 (in each of the X and Y directions in the sense of Figure 7) and the provision of the inclined faces 102c1 -6 (or inclined flow guiding surfaces) cause the flow F of the burden material to be directed simultaneously down and across the front face 302 of the stave 300 (i.e. in a direction having a component in each of the X and Y directions in the sense of Figure 7). In this way the burden material percolates down between the inserts 100. Thus the burden material is very effectively distributed between the inserts 100 with the result that burden material becomes trapped by the inserts 100 along substantially the entire length and width of the front face 302. Accordingly the stave 300 is well protected by the burden material.

Furthermore portions of the burden material which flows down over the front faces 102a of the projection parts 102 of the inserts 100 will be received in the recesses 102d which are defined therein.

It will be understood that the extent of the flow (F) of the burden material across the front face 302 of the stave 300 in each of the X and Y directions may depend on the flow conditions, including for example the volume and weight of the burden material, and its flow rate, temperature and viscosity. In this regard the progress of the flow (F) of an amount of burden material may be limited, such that said amount of burden material might not cover substantially the entire length and width of the front face 302, but rather be trapped between inserts 100 at one or more local regions of the front face 302. Of course, a further amount of burden material may be caused to flow over the stave 300 and be trapped between inserts 100 at other local regions, such that, over time, substantially the entire length and width of the front face 302 becomes covered by trapped burden material.

Over time the inserts 100 and spacers 200 will be worn down by the abrasive action of the burden material. The spacers 200, which in the described embodiment are constructed from copper alloy, may wear at a higher rate than the harder silicon carbide inserts 100. As the spacers 200 wear their front faces 200a will recede into the depths of the grooves 312 so as to leave spaces in the grooves 312. These spaces are“stoneboxes” which will become occupied by the burden material. Similar stoneboxes may be formed and occupied by burden material when the attachment parts 104 of the inserts 100 eventually wear out. In this way the burden material protects the stave 300 even after all of the spacers 200 and inserts 100 have been eroded away. While in the described exemplary embodiment the spacers 200 each comprise a solid block having a thickness which is approximately equal to the depth of the groove 312, it will be understood that the spacers could take a different form. For example, in an alternative embodiment at least one of the spacers comprises a rectangular (optionally square) frame. That is, the spacer resembles a picture frame, so that when the spacer is installed in the groove 312 a portion of the floor 312a of the groove 312 is left uncovered by the spacer and exposed to view. This provides a stonebox which can become occupied by burden material before any wear of the spacer occurs. In such an embodiment the thickness of the spacer may be the same as, or less than, the depth of the groove 312. The spacer may be configured in various other ways to leave some portion of the floor 312a of the groove 312 exposed and all such configurations are within the scope of the claimed invention.

Furthermore the spacers need not be discrete elements. In an alternative embodiment, one or more of the spacers is an integral part of one or more of the inserts 100. For example, in one such embodiment a spacer is comprised by a laterally-extending flange portion of the attachment part 104 of the insert 100.

Moreover any or all of the spacers may be omitted, since the inserts 100 could be positioned at the desired spacing and then individually attached to the stave 300 (by means of screw connections or welds as described herein above, for example) to prevent the inserts 100 from moving laterally out of position.

While the described embodiment relates to inserts having hexagonal projection parts, it will be understood that one or more of the projection parts could take a different shape. Preferably each of the projection parts is polyhedral. That is, each of the projection parts is a three-dimensional solid comprising flat polygonal faces, straight edges and sharp corners or vertices. For example, the flat polygonal face could be a triangle, a rectangle (for example a square), a pentagon, a heptagon, an octagon, and so on. All of these shapes are within the scope of the claimed invention. Alternatively one or more of the projection parts may have a circular flat face, such that the projection part takes the form of a disc. Also the projection parts of the inserts may be of dissimilar shape and/or size. Furthermore the recesses in the projection parts may be other than circular or may even be omitted.

Referring to Figures 8, in an embodiment at least one of the grooves 312 comprises no spacers. The side faces 104a, 104b of the attachment parts 104 of the inserts 100 are in abutment so as to form a continuous ledge which can prevent the passage of burden material between the inserts 100. This may be particularly useful at or near the bottom of the stave 300, as shown in Figure 8, since it is desirable to try to retain as much burden material as possible on the stave

Claims

1. A stave protection system for a metallurgical furnace, comprising:

a stave (300) comprising a front face (302) having an X direction and a Y direction which is perpendicular to the X direction such as to define an X-Y plane, the front face (302) comprising rows of grooves (312) which extend in the X direction; and

inserts (100) which are slidingly received by the grooves (312), the inserts (100) so received by each respective groove (312) being spaced apart from each other along the groove (312), the centres of the inserts (100) which are received by one of the grooves (312) being offset in each of the X and Y directions from the centres of the inserts (100) which are received by an adjacent groove (312), each of the inserts (100) projecting from the front face (302) of the stave (300) and comprising flow guiding surfaces (102c1 -6) which are inclined with respect to each of the X and Y directions in the X-Y plane,

such that in use the offsets of the inserts (100) in each of the X and Y directions and the inclined flow guiding surfaces (102c1 -6) cause a flow (F) of furnace burden material, under gravity, to flow in a direction having a component in each of the X and Y directions, so as to distribute the burden material between the inserts (100) over the front face (302) of the stave (300) and/or trap the burden material between the inserts (100).

2. A stave protection system according to claim 1 , wherein the offset in the X direction is such that an imaginary line (L2), which extends in the Y direction, intersects flow guiding surfaces (102c1-6) of the inserts (100) which are received by the one of the grooves (312) and flow guiding surfaces (102c1 -6) of the inserts (100) which are received by the adjacent groove (312).

3. A stave protection system according to claim 1 , wherein the offset in the Y direction is such that an imaginary line (L1 ), which extends in the X direction, intersects flow guiding surfaces (102c1-6) of the inserts (100) which are received by the one of the grooves (312) and flow guiding surfaces (102c1 -6) of the inserts (100) which are received by the adjacent groove (312).

4. A stave protection system according to claim 1 , wherein:

the offset in the X direction is such that an imaginary line (L2), which extends in the Y direction, intersects flow guiding surfaces (102c1 -6) of the inserts (100) which are received by the one of the grooves (312) and flow guiding surfaces (102c1 -6) of the inserts (100) which are received by the adjacent groove (312); and

the offset in the Y direction is such that an imaginary line (L1 ), which extends in the X direction, intersects flow guiding surfaces (102c1 -6) of the inserts (100) which are received by the one of the grooves (312) and flow guiding surfaces (102c1 -6) of the inserts (100) which are received by the adjacent groove (312).

5. A stave protection system according to any preceding claim, wherein the offset in the X direction is such that:

the distance in the X direction, between the centres of the inserts (100) which are received by the one of the grooves (312), is D; and

the distance in the X direction, between the centres of the inserts (100) which are received by the adjacent groove (312) and the centres of the inserts (100) which are received by the one of the grooves (312), is D/2.

6. A stave protection system according to any preceding claim, wherein each of the flow guiding surfaces (102c1 -6) is perpendicular to the front face (302) of the stave (300).

7. A stave protection system according to any preceding claim, wherein each insert (100) comprises a projection part (102) which includes the flow guiding surfaces (102c1 -6) and an attachment part (104) which is received by the respective groove (312).

8. A stave protection system according to claim 7, wherein the insert (100) is of unitary construction such that the projection part (102) and the attachment part (104) are integral.

9. A stave protection system according to claim 7, wherein the insert (100) is of non-unitary construction such that the projection part (102) and the attachment part (104) are discrete elements.

10. A stave protection system according to any one of claims 7 to 9, wherein the projection part is polyhedral and sides of the projection part (102) comprise the flow guiding surfaces (102c1 -6).

1 1. A stave protection system according to claim 10, wherein the projection part (102) is hexagonal and each one of four of the six sides of the projection part (102) comprises a respective one of the inclined flow guiding surfaces (102c1 -6).

12. A stave protection system according to claim 1 1 , wherein the other two sides of the hexagonal projection part (102) each extend in the Y direction.

13. A stave protection system according to claim 1 1 , wherein the other two sides of the hexagonal projection part (102) each extend in the X direction.

14. A stave protection system according to any one of claims 7 to 13, wherein the projection part (102) comprises a recess (102d).

15. A stave protection system according to any preceding claim, wherein the inserts (100) which are received by each respective groove (312) are spaced apart from each other along the groove (312) by spacers (200) which are slidingly received in the groove (312), the spacers (200) being configured to expose the surfaces of the respective grooves (312) between the inserts (100).