Inner surface of furnace

Abstract

The present invention relates to a furnace having an inner surface (2) comprising copper. The inner surface (2) comprises at least one steel insert (1), the at least one steel insert (1) creating a protrusion extending from the inner surface (2). The present invention also relates to a cooling element (17) for a furnace comprising at least one steel insert (1) creating a protrusion extending from the cooling element (17). The present invention also relates to a method for generating an autogenous protective layer on the inner surface (2) of a furnace and to the use of the furnace in a direct iron reduction process, electric smelting process, electric reduction process, flash smelting process, flash converting process, bath smelting process or bath converting process.

Description

[0001] INNER SURFACE OF FURNACE

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a furnace having an inner surface comprising copper, wherein the inner surface comprises at least one steel insert . The invention also relates to a cooling element comprising at least one steel insert , a method for generating an autogenous protective layer on the inner surface of a furnace and the use of the furnace in a direct iron reduction process , electric smelting process , electric reduction process , flash smelting process , flash converting process , bath smelting process or bath converting process .

[0004] BACKGROUND OF THE INVENTION

[0005] Furnaces used in electric smelting processes , electric reduction processes , flash smelting processes , flash converting processes , bath smelting processes and bath converting processes typically have a gas phase zone and a liquid phase zone . The liquid phase zone may be the lower portion of a furnace where , e . g . , matte or metal alloy or metal and slag would be present when the furnace is in operation . The gas phase zone may be the corresponding upper portion of the furnace . During operation, gas may be fed to the furnace and gas may also be generated in the furnace . The gas usually has a high temperature and may contain small , melted particles . This may cause abrasion on the inner surface of the furnace in the gas phase zone . Also , the matte or metal alloy or metal and slag present in the liquid phase zone have high temperatures . Thi s may cause abrasion on the inner surface of the furnace in liquid phase zone . The inner surface of furnaces often contain copper . The copper can be covered with bricks in order to protect the copper from abrasion . However , this increases the production cost of the furnaces . Also , the bricks may wear over time due to the hot gas and small melted particles and might need to be replaced at certain intervals .

[0006] As such, there in a need for improving the inner surface of furnaces .

[0007] SUMMARY

[0008] According to a first aspect , a furnace having an inner surface comprising copper, wherein the inner surface comprises at least one steel insert , the at least one steel insert creating a protrusion extending from the inner surface is provided .

[0009] According to a second aspect , a cooling element for a furnace is provided, the cooling element comprising a hous ing, the housing comprising channels for the flow of cooling water or refrigerants , wherein the cooling element further comprises at least one steel insert , the at least one steel insert creating a protrusion extending from the hot side of the cooling element .

[0010] According to a third aspect , a method for generating an autogenous protective layer on the inner surface of a furnace having an inner surface according to the first aspect is provided, the method comprising capturing melted or solid particles present in the furnace during operation, wherein the melted or solid particles are captured on the at least one steel insert .

[0011] According to a fourth aspect , the use of the furnace according to the first aspect , or the use of the cooling element according to the second aspect in a furnace in a direct iron reduction process , electric smelting process , electric reduction process , flash smelting process , flash converting process , bath smelting process or bath converting process is provided .

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention . In the drawings :

[0014] Figure 1 shows a furnace having an inner surface comprising steel inserts ;

[0015] Figure 2 shows a reaction shaft of a furnace wherein the inner surface in the roof of the reaction shaft comprises steel inserts ;

[0016] Figure 3 shows the inner surface of the roof of a reaction shaft of a furnace , the inner surface of the roof comprising hourglass / double-dovetail shaped steel inserts ;

[0017] Figure 4 shows a cross section of a wall , bottom or roof of a furnace , wherein hourglass / double-dovetail shaped steel inserts are embedded in the wall , bottom or roof of the furnace ; and

[0018] Figure 5 shows a cooling element comprising steel inserts .

[0019] DETAILED DESCRIPTION It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described below, instead they may vary within the scope of the claims.

[0020] The description related to the furnace below also apply to the cooling element described below and vice versa.

[0021] A furnace having an inner surface comprising at least one steel insert

[0022] According to a first aspect and as seen in figure 1, a furnace having an inner surface (2) comprising copper, wherein the inner surface (2) comprises at least one steel insert (1) , the at least one steel insert (1) creating a protrusion extending from the inner surface (2) is provided.

[0023] The furnace may be a flash smelting furnace or a flash converting furnace. The furnace may comprise the following : i. a reaction shaft (3) provided with a burner (5) for burning concentrate or matte (6) and feeding concentrate or matte (6) into the reaction shaft (3) to form a jet of an at least partially oxidised suspension in the reaction shaft (3) ; ii. a settler (8) in communication with a lower end of the reaction shaft (3) , wherein the settler (8) has an inner space and a first end wall structure (16) at one end of the settler (8) and a second end wall structure (15) at the opposite end of the settler (8) and a landing zone for the jet of the at least partially oxidised suspension in the inner space of the settler (8) below the lower end of the reaction shaft (3) , and wherein the settler (8) is configured to receive the at least partially oxidised suspension from the reaction shaft (3) at the landing zone and to form a layer of matte or metal alloy (10) and a layer of slag (9) on top of the layer of matte or metal alloy (10) in the inner space of the settler (8) ; iii. a first taphole (11) for discharging slag (12) from the layer of slag (9) in the inner space of the settler (8) , and a second taphole (14) for discharging matte or metal alloy (13) from the layer of matte or metal alloy (10) in the inner space of the settler ( 8 ) ; and vi . an uptake shaft (4) for leading process gases (7) from the furnace via the uptake shaft (4) , wherein the uptake shaft (4) has a lower end in communication with the settler (8) .

[0024] The term in communication with may refer to an open space being available between the discussed components such that the components share the open space, and such that material can be freely exchanged between the components .

[0025] The settler (8) may further comprise two side walls, a bottom and a roof extending between the first end wall structure (16) and second end wall structure (15) . The end wall structures (16, 15) may have the form of a square or rectangle such that the side walls, bottom and roof extend from the peripheries of the first end wall (16) to the peripheries of the second end wall (15) , and thereby form a closed space between the end walls (27,28) , bottom, roof and sidewalls. The reaction and uptake shafts (3, 4) may be located in or on the roof and the layer of slag and matte or metal alloy (9, 10) may rest on the bottom when the device is in operation.

[0026] Accordingly, the bottom and the roof may extend substantially in the horizontal direction and the end walls (16, 15) as well as the side walls may extend substantially in the vertical direction when the device is placed on the surface on which it is to be used.

[0027] In this disclosure, vertical may mean the direction of gravity and horizontal may mean the direction that is perpendicular to the vertical direction.

[0028] Also in this disclosure, substantially horizontally and / or vertically may mean to a great or significant extent horizontally and / or vertically. For instance, substantially vertically / horizontally could mean a completely vertical / horizontal direction or a deviation from the vertical / horizontal direction with 2°, or 4°, or 6°, or 8°, or 10°. For example, the bottom may slope downwardly for example in an inclined and / or curved manner towards the first and second taphole (11, 14) for facilitating the discharge of slag and matte or metal alloy (9, 10) , thus deviating from the completely horizontal direction with, e.g., 2°.

[0029] The reaction and uptake shafts (3, 4) may have the shape of a cylinder, cube or cuboid such that they have a bottom, roof and one or more walls. The bottom and roof may extend substantially in the horizontal direction and the one or more walls may extend substantially in the vertical direction. The reaction and uptake shafts (3, 4) may be arranged in or on the roof of the settler (8) . Therefore, the reaction and uptake shafts (3, 4) may have an opening in the bottom or may lack a bottom such that the reaction and uptake shafts (3, 4) are in communication with the settler (8) .

[0030] For the avoidance of doubt, the inner surface (2) comprising copper may refer to the complete inner surface of the furnace, e.g. the inner surface of the settler (8) , the reaction shaft (3) and the uptake shaft (4) . This is including the walls, bottom and roof of the settler (8) and the walls, roof and possible bottom of the reaction and uptake shafts (3, 4) . Accordingly, a reference to the wall, bottom or roof of a furnace may refer to the wall, bottom or roof of the settler, reaction shaft and uptake shaft (8, 3, 4) . Also for the avoidance of doubt, the furnace may refer to the settler, reaction shaft and uptake shaft (8, 3, 4) .

[0031] Further for the avoidance of doubt, even if some examples may refer to a flash smelting furnace and flash converting furnace, the furnace may be an electric furnace, bath smelting furnace, bath converting furnace or electric reduction furnace. The electric furnace may be a direct iron reduction furnace. Thus, the inner surface (2) comprising copper may refer to the complete inner surface of an electric furnace, bath smelting furnace, bath converting furnace or electric reduction furnace .

[0032] The inner surface (2) of the furnace may comprise copper such that the surface is covered with a layer of copper. The inner surface (2) comprising copper may be composed of cooling elements (17) . Accordingly, the inner surface (2) may comprise one or more cooling elements (17) comprising copper. A cooling element (17) may refer to a component designed to manage extreme temperatures generated during the smelting process. The cooling elements (17) may contain channels (19) for the flow of cooling water or refrigerants. For the avoidance of doubt, a reference to the inner surface (2) may refer to the hot side of the cooling element (17) and a reference to the wall, bottom or roof of the furnace may refer to the cooling element (s) (17) being an integrated part of the wall, bottom or roof. The hot side of the cooling element (17) may refer to the part of the cooling element (17) facing the inside of the furnace.

[0033] In this disclosure, a protrusion typically refers to an element or feature that extends outward from a surface or structure. It could be a raised portion, a bulge, or an extension that extends beyond the general profile of the object, i.e. the inner surface (2) of the furnace .

[0034] For the avoidance of doubt, when the inner surface (2) comprises more than one steel insert (1) , each steel insert (1) may create a protrusion extending from the inner surface (2) .

[0035] The inventors have found that steel inserts (1) creating protrusions in the inner surface (2) of furnaces protect the inner surface (2) and prevent abrasion. These steel inserts (1) are more resistant to heat compared to an inner surface (2) comprising copper. Without wishing to be bound by theory, it is believed that the protrusions decrease the velocity of hot gas and melted material inside the furnace between the protrusions, which prevents or decreases the wear of the inner surface (2) . Additionally, solid or melted particles inside the furnace may attach to the protrusions, thus not causing wear on the copper of the inner surface (2) .

[0036] The steel insert (1) according to the first aspect may have an elongated shape.

[0037] In this disclosure, elongated shape may refer to a geometric form that is characterized by having one dimension significantly longer than the others.

[0038] The steel insert (1) may have the shape of a rod or beam. The steel insert (1) may have the shape of a beam in the longitudinal direction and the shape of a rectangle or rounded rectangle or hourglass or a double dovetail or a combination of these in the transverse direction. Accordingly, the transverse direction of the steel insert (1) may have a narrowing waist section between broader top and bottom sections. The broader top and bottom sections may have different sizes and slightly different shapes. For the avoidance of doubt, the longitudinal direction refers to the direction along the length of the elongated shape and the transverse directions refers to the directions perpendicular to the longitudinal direction, encompassing both width and height or diameter.

[0039] The steel insert (1) according to the first aspect may have dimensions of at least 0.1 x 0.02 x 0.005 m, or 0.1 x 0.02 x 0.005 m to 5.0 x 0.07 x 0.05 m, or 2.0 x 0.04 x 0.01 m to 3.0 x 0.05 x 0.03 m.

[0040] The above dimensions may refer to the length of the longitudinal direction x the height of the transverse direction x the width of the transverse direction. In other words, the above dimensions may refer to the smallest box into which the steel insert (1) would fit. When the inner surface (2) comprises more than one steel inserts (1) , the steel inserts (1) may have different dimensions compared to each other.

[0041] The steel insert (1) may be embedded in the wall, bottom or roof of the furnace as seen in figure 4, which is a cross-section of a wall, bottom or roof of a furnace where steel inserts (1) are embedded in the wall, bottom or roof. In this figure, the hourglass shaped transverse direction of a plurality of steel inserts (1) are shown. The steel insert (1) may be embedded in the wall, bottom or roof of the furnace such that 1 / 2 of the steel insert (1) is embedded and 1 / 2 of the steel insert (1) creates a protrusion extending from the wall, or such that 2 / 3 of the steel insert (1) is embedded and 1 / 3 of the steel insert (1) creates a protrusion extending from the wall, or such that 3 / 4 of the steel insert (1) is embedded and 1 / 4 of the steel insert (1) creates a protrusion extending from the wall.

[0042] The steel inserts (1) may additionally or alternatively be attached to the wall, bottom or roof through attaching means. The attaching means may extend through the wall, bottom or roof of the furnace such that the attaching means are attached to the steel inserts (1) in one end and attached to the outside of the wall, bottom or roof of the furnace in another end. When attaching means are used, the steel inserts (1) may be partially embedded in the wall, bottom or roof of the furnace, or the steel inserts (1) may be attached to the attaching means such that the attaching means extends completely through the wall, bottom or roof. The steel inserts (1) may be attached to the wall, bottom or roof through its shape, e.g. by having a dove tail shape. Figure 3 represents a reaction shaft (3) roof where steel inserts (1) protruding towards the inner space of the furnace are arranged in the roof of the reaction shaft (3) . As seen in this figure, if the steel insert (1) has the shape of an hourglass in the transverse direction, the steel insert (1) may be embedded in the wall, bottom or roof of the furnace such that the broader top and bottom sections of the transverse direction extend towards an outside of the furnace and towards the inner space of the furnace. Accordingly, the narrowing waist section of the transverse direction of the steel insert (1) may be located at or close to the interface between the inner space of the furnace and the inner surface (2) of the furnace.

[0043] The longitudinal direction of the steel insert (1) according to the first aspect may extend substantially horizontally along the inner surface (2) of the furnace .

[0044] The steel insert (1) may be arranged on the inner surface (2) of the furnace such that the direction of flow of gas, when the furnace is in operation, is substantially perpendicular to the longitudinal direction of the steel insert (1) . Accordingly, the longitudinal direction of the steel insert (1) may extend substantially parallel to the bottom and roof of the furnace. In other words, the end points of the steel insert

[0045] (1) having an elongated shape may point substantially towards the walls of the furnace rather than towards the bottom and roof of the furnace, regardless of whether the steel insert (1) is arranged on the inner surface

[0046] (2) of the wall, bottom or roof of the furnace. The inventors have found that a steel insert (1) having the above discussed shape, orientation and dimensions is particularly useful for decreasing the velocity of hot gas and melted material between the protrusions inside the furnace and for capturing solid or melted particles inside the furnace.

[0047] The inner surface (2) of the furnace according to the first aspect may comprise at least 5, or at least 10, or at least 15, or at least 20, or at least 25, or at least 30 steel inserts (1) .

[0048] The inner surface (2) of the furnace may comprise at least 40, or at least 50, or at least 60, or at least 70, or at least 80, or at least 90 of the steel inserts ( 1 ) .

[0049] The inner surface (2) of the furnace may comprise 300 or less, or 280 or less, or 260 or less, or 240 or less, or 220 or less, or 200 or less of the steel inserts ( 1 ) .

[0050] The steel inserts (1) according to the first aspect may create a lamellar structure on the inner surface (2 ) .

[0051] In this disclosure, a lamellar structure may refer to a specific arrangement where the protruding steel inserts (1) form parallel layers or sheets, i.e. the protruding steel inserts (1) may be stacked one above or next to the other in a repetitive manner, with each steel insert (1) maintaining a consistent orientation relative to its neighbouring elements. Preferably, the steel inserts (1) may be arranged on the inner surface (2) such that they are stacked substantially vertically on top of each other, if the steel inserts (1) are arranged on a wall, or such that they are stacked substantially horizontally next to each other, if the steel inserts (1) are arranged on the bottom or in the roof. For the avoidance of doubt, being stacked on top of or next to each other does not necessarily mean that the steel inserts (1) touch each other. For example, the steel inserts (1) may be arranged such that a first steel insert (1) is arranged on the inner surface (2) of the furnace so that the longitudinal direction of the steel insert (1) extend substantially horizontally along the inner surface (2) of the furnace, and a second steel insert (1) is similarly arranged vertically above or below or horizontally next to the first steel insert (1) at a certain vertical or horizontal distance from the first steel insert (1) , and a third steel insert (1) is similarly arranged vertically above or below or horizontally next to the second steel insert (1) at a certain vertical or horizontal distance from the second steel insert ( 1 ) , etc . .

[0052] The steel inserts (1) may be arranged in the lamellar structure such that their longitudinal directions are parallel to each other and face each other directly, rather than being oriented such that their transverse directions face each other. For the avoidance of doubt, some steel inserts (1) transverse directions may face each other if several lamellar structures are arranged on the inner surface (2) of the furnace adjacent to each other.

[0053] The distance between the longitudinal directions of the steel inserts (1) in the lamellar structure may be at least 0.001 m, or 0.002 m, or 0.003 m, or 0.004, or 0.005 m. The distance between the longitudinal directions of the steel inserts (1) in the lamellar structure may be 0.001 to 0.01 m, or 0.002 to 0.009 m, or 0.003 to 0.008 m, or 0.004 to 0.007 m, or 0.005 to 0.006 m.

[0054] The distance may be measured as follows. When a first and second steel insert (1) is arranged on the inner surface (2) of the furnace such that their longitudinal directions face each other, the distance is the distance between a point in the first steel insert (1) and a point in the second steel insert (1) that create the shortest distance between the first and second steel inserts ( 1 ) .

[0055] The steel inserts (1) according to the first aspect in the lamellar structure may be arranged such that gaps are created between the steel inserts (1) .

[0056] Accordingly, the steel inserts (1) may be arranged in a lamellar structure as explained before, such that the protrusions are arranged at a certain distance from each other and such that no other material is placed between the protrusions. For the avoidance of doubt, this space may be occupied by material inside the furnace when the furnace is in operation. Also, this space may contain some temporary mass there between. However, e.g. the open space created between the steel inserts

[0057] (1) , i.e. the gap, does not contain bricks.

[0058] It has been found that a lamellar structure as discussed above is particularly useful for protecting the inner wall of the furnace. The velocity of gas and melted material reaching the copper of the inner surface

[0059] (2) may be significantly decreased and particles present in the gas of melted material may be attached to the steel inserts (1) . Further, the particles attached to the steel inserts (1) may build up over time and create a protective layer on the inner surface (2) .

[0060] The steel insert (1) according to the first aspect may be arranged on the inner surface (2) of a gas phase zone of the furnace.

[0061] The steel insert (1) according to the first aspect may be arranged on the inner surface (2) of a liquid phase zone of the furnace.

[0062] A layer of matte or metal alloy (10) and a layer of slag (9) on top of the layer of matte or metal alloy (10) may be formed in the inner space of the settler (8) when the furnace is in operation. The gas phase zone of the furnace may refer to the inner space of the furnace that is above the layer of slag (9) when the furnace is in use. The liquid phase zone of the furnace may refer to the inner space of the furnace that is below the gas phase zone of the furnace.

[0063] The furnace according to the first aspect may comprises a reaction shaft (3) and the steel insert (1) may be arranged on the inner surface (2) in the roof of the reaction shaft (3) .

[0064] As seen in figure 2, several steel inserts (1) may be arranged on the inner surface (2) in the roof of the reaction shaft (3) . For example, the steel inserts (1) may be arranged such that the longitudinal direction of the steel inserts (1) are parallel to the periphery of the roof, i.e. if the reaction shaft (3) has the shape of a cube, cuboid, pentagonal prism, hexagonal prism, heptagonal prism, octagonal prism, nonagonal prism, etc. , the steel inserts (1) may be placed such that the steel inserts (1) crate a square-like pattern or a pentagon, hexagon, heptagon, octagon, nonagon, etc., in the roof. Alternatively, the steel inserts (1) may be placed such that the steel inserts (1) crate a square-like pattern or a pentagon, hexagon, heptagon, octagon, nonagon, etc., in the roof, irrespective of the shape of the reaction shaft.

[0065] The inventors have found that the inner surface (2) of the gas phase zone and specifically in the roof of the reaction shaft (3) is particularly exposed to gas having a high temperature and to solid or melted particles present in the gas. Thus, the steel inserts (1) described herein are particularly useful when placed in these locations.

[0066] The steel insert (1) may comprise steel and in particular high temperature resistant steel and / or high corrosion resistant steel. The steel insert (1) may consist of steel and in particular high temperature resistant steel and / or high corrosion resistant steel.

[0067] A cooling element for a furnace

[0068] According to a second aspect, a cooling element (17) for a furnace is provided, the cooling element (17) comprising a housing (18) , the housing (18) comprising channels (19) for the flow of cooling water or refrigerants, wherein the cooling element (17) further comprises at least one steel insert (1) , the at least one steel insert (1) creating a protrusion extending from the hot side of the cooling element (17) .

[0069] The cooling element (17) may be for a flash smelting or flash converting furnace. The cooling element (17) may be for an electric furnace, bath smelting furnace, bath converting furnace or electric reduction furnace. The electric furnace may be a direct iron reduction furnace.

[0070] For the avoidance of doubt, when the cooling element (17) comprises more than one steel insert (1) , each steel insert (1) may create a protrusion extending from the from the cooling element (17) .

[0071] The housing (18) may refer to the outer structure that contains and protects the channels (19) .

[0072] The housing (18) may comprise or consist of copper. The channels (19) may comprise or consist of copper .

[0073] The hot side of the cooling element (17) may refer to the side of the cooling element (17) that faces the inside of the furnace when the cooling element (17) is used in a furnace. The cold side of the cooling element (17) may refer to the opposite side.

[0074] The inventors have found that steel inserts (1) creating protrusions from the cooling element (17) protect the cooling element (17) and prevent abrasion when the cooling element (17) is used in a furnace. The steel inserts (1) are more resistant to heat compared to the housing (18) . Without wishing to be bound by theory, it is believed that the protrusions decrease the velocity of hot gas and melted material inside the furnace between the protrusions, which prevents or decreases the wear of the housing (18) . Additionally, solid or melted particles inside the furnace may attach to the protrusions, thus not causing wear on the housing (18) .

[0075] The steel insert (1) according to the second aspect may have an elongated shape.

[0076] The steel insert (1) according to the second aspect may have dimensions of at least 0.1 x 0.02 x 0.005 m, or 0.1 x 0.02 x 0.005 m to 5.0 x 0.07 x 0.05 m, or 2.0 x 0.04 x 0.01 m to 3.0 x 0.05 x 0.03 m.

[0077] The above dimensions may refer to the length of the longitudinal direction x the height of the transverse direction x the width of the transverse direction. In other words, the above dimensions may refer to the smallest box into which the steel insert (1) would fit.

[0078] The steel insert (1) may be embedded in the housing (18) . The steel insert (1) may be embedded such that 1 / 2 of the steel insert (1) is embedded and 1 / 2 of the steel insert (1) creates a protrusion extending from the housing (18) , or such that 2 / 3 of the steel insert (1) is embedded and 1 / 3 of the steel insert (1) creates a protrusion extending from the housing (18) , or such that 3 / 4 of the steel insert (1) is embedded and 1 / 4 of the steel insert (1) creates a protrusion extending from the housing (18) .

[0079] The steel insert (1) may have the shape of a hourglass in the transverse direction, and the steel insert (1) may be embedded in the housing (18) such that the broader top and bottom sections of the transverse direction extend towards an outside of the furnace and towards the inner space of the furnace when the cooling element (17) is used in a furnace. Accordingly, the narrowing waist section of the transverse direction of the steel insert (1) may be located at or close to the interface between the housing (18) and the outside environment .

[0080] The longitudinal direction of the steel insert (1) according to the first aspect may extend substantially perpendicularly to the channels (19) . The steel inserts (1) may be arranged on the housing (18) such that the cooling elements (17) may be arranged in the inner surface (2) of a furnace such that the longitudinal direction of the steel inserts (1) extend substantially in the horizontal direction.

[0081] The inventors have found that a steel insert

[0082] (1) having the above discussed shape, orientation and dimensions is particularly useful for decreasing the velocity of hot gas and melted material between the protrusions inside the furnace and for capturing solid or melted particles inside the furnace. Also, having the channels (19) arranged perpendicularly to the steel inserts (1) provide good heat transfer between the cooling water / ref rigerant and the steel inserts (1) .

[0083] The cooling element (17) according to the second aspect may comprise at least 3, or at least 6, or at least 9, or at least 12, or at least 14 steel inserts (1) •

[0084] The cooling element (17) may comprise 30 or less, or 27 or less, or 24 or less, or 21 or less, or 18 or less, or 15 or less of the steel inserts (1) .

[0085] The steel inserts (1) according to the second aspect may create a lamellar structure on cooling element ( 17 ) .

[0086] Preferably, the steel inserts (1) may be arranged on the cooling element (17) such that when the cooling element (17) is arranged in the inner surface

[0087] (2) of a furnace, the steel inserts (1) may be arranged on the inner surface (2) such that they are stacked substantially vertically on top of each other, if the steel inserts (1) are arranged on a wall, or such that they are stacked substantially horizontally next to each other, if the steel inserts (1) are arranged on the bottom or in the roof.

[0088] The steel inserts (1) may be arranged in the lamellar structure such that their longitudinal directions are parallel to each other and face each other directly, rather than being oriented such that their transverse directions face each other. For the avoidance of doubt, some steel inserts (1) transverse directions may face each other if several lamellar structures are arranged on the cooling element (17) adjacent to each other .

[0089] The distance between the longitudinal directions of the steel inserts (1) according to the second aspect in the lamellar structure may be at least 0.001 m, or 0.002 m, or 0.003 m, or 0.004, or 0.005 m.

[0090] The distance may be measured as follows. When a first and second steel insert (1) is arranged on the cooling element (17) such that their longitudinal directions face each other, the distance is the distance between a point in the first steel insert (1) and a point in the second steel insert (1) that create the shortest distance between the first and second steel inserts ( 1 ) .

[0091] The steel inserts (1) according to the second aspect in the lamellar structure may be arranged such that gaps are created between the steel inserts (1) .

[0092] It has been found that a lamellar structure as discussed above is particularly useful for protecting the inner wall of a furnace. The velocity of gas and melted material reaching the copper may be significantly decreased and particles present in the gas of melted material may be attached to the steel inserts (1) . Further, the particles attached to the steel inserts (1) may build up over time and create a protective layer on the inner surface (2) .

[0093] The steel insert (1) may comprise steel and in particular high temperature resistant steel and / or high corrosion resistant steel. The steel insert (1) may consist of steel and in particular high temperature resistant steel and / or high corrosion resistant steel.

[0094] A method for protecting the inner surface of a furnace

[0095] According to a third aspect, a method for generating an autogenous protective layer on the inner surface (2) of a furnace having an inner surface (2) according to the first aspect is provided, the method comprising capturing melted or solid particles present in the furnace during operation, wherein the melted or solid particles are captured on the at least one steel insert ( 1 ) .

[0096] In this disclosure, generating an autogenous protective layer may refer to the spontaneous or selfgenerated buildup of a layer.

[0097] Operation of a flash smelting of flash converting furnace may comprise the following: i. feeding concentrate or matte (6) by means of a burner (5) for burning concentrate or matte (6) into a reaction shaft (3) of the furnace to form a jet of an at least partially oxidised suspension in the reaction shaft (3) ; ii. receiving the jet of an at least partially oxidised suspension in a landing zone of a settler (8) in communication with a lower end of the reaction shaft (3) ; iii. forming a layer of matte or metal alloy (10) and a layer of slag (9) on top of the layer of matte or metal alloy (10) in the inner space of the settler ( 8 ) ; iv. discharging slag (12) from the layer of slag (9) in the settler (8) through a first taphole (11) and discharging matte or metal alloy (13) from the layer of matte or metal alloy (10) in the settler (8) through a second taphole (14) ; and v. leading process gases (7) from the furnace via an uptake shaft (4) having a lower end in communication with the settler (8) .

[0098] The process gases (7) may comprise sulfur dioxide, carbon dioxide, water, metal containing vapors, nitrogen and some reaction shaft product in the form of unsettled suspension particles. The unsettled suspension particles may be the solid or melted particles.

[0099] The inventors have found that these solid or melted particles surprisingly may attach to the steel inserts (1) described herein. The steel inserts (1) do not wear as easily and the inner surface (2) comprising copper. The solid or melted particles may adhere to the steel inserts (1) and gradually accumulate during operation of the furnace. This may result in the formation of the autogenous protective layer on the inner surface (2) of a furnace.

[0100] The matte or metal alloy and slag may also comprise solid or melted particles that surprisingly may attach to the steel inserts (1) described herein. Also these solid or melted particles may adhere to the steel inserts (1) and gradually accumulate during operation of the furnace. This may result in the formation of the autogenous protective layer on the inner surface (2) of a furnace .

[0101] Use According to a fourth aspect, the use of the furnace according to the first aspect, or the use of the cooling element according to the second aspect in a furnace, in a direct iron reduction process, electric smelting process, electric reduction process, flash smelting process, flash converting process, bath smelting process or bath converting process is provided.

Claims

CLAIMS1. A furnace having an inner surface (2) comprising copper, wherein the inner surface (2) comprises at least one steel insert (1) , the at least one steel insert (1) creating a protrusion extending from the inner surface (2 ) .

2. The furnace according to claim 1, wherein the steel insert (1) has an elongated shape.

3. The furnace according to claims 1 or 2, wherein the steel insert (1) has dimensions of at least 0.1 x 0.02 x 0.005 m, or 0.1 x 0.02 x 0.005 m to 5.0 x 0.07 x 0.05 m, or 2.0 x 0.04 x 0.01 m to 3.0 x 0.05 x 0.03 m.

4. The furnace according to any preceding claims, wherein the longitudinal direction of the steel insert (1) extends substantially horizontally along the inner surface (2) of the furnace.

5. The furnace according to any preceding claims, wherein the inner surface (2) comprises at least 5, or at least 10, or at least 15, or at least 20, or at least 25, or at least 30 steel inserts (1) .

6. The furnace according to claim 5, wherein the steel inserts (1) create a lamellar structure on the inner surface (2) .

7. The furnace according to claim 6, wherein the distance between the longitudinal directions of thesteel inserts (1) in the lamellar structure is at least0.001 m, or 0.002 m, or 0.003 m, or 0.004, or 0.005 m.

8. The furnace according to any of claims 5 to 7, wherein the steel inserts (1) in the lamellar structure are arranged such that gaps are created between the steel inserts (1) .

9. The furnace according to any preceding claims, wherein the steel insert (1) is arranged on the inner surface (2) of a gas phase zone of the furnace.

10. The furnace according to any preceding claims, wherein the steel insert (1) is arranged on the inner surface (2) of a liquid phase zone of the furnace.

11. The furnace according to claim 9, wherein the furnace comprises a reaction shaft (3) , and wherein the steel insert (1) is arranged on the inner surface (2) in the roof of the reaction shaft (3) .

12. A cooling element (17) for a furnace, the cooling element (17) comprising a housing (18) , the housing (18) comprising channels (19) for the flow of cooling water or refrigerants, wherein the cooling element (17) further comprises at least one steel insert (1) , the at least one steel insert (1) creating a protrusion extending from the hot side of the cooling element ( 17 ) .

13. The cooling element according to claim 12, wherein the steel insert (1) has an elongated shape.

14. The cooling element according to claims 12 or 13, wherein the steel insert (1) has dimensions of at least 0.1 x 0.02 x 0.005 m, or 0.1 x 0.02 x 0.005 m to 5.0 x 0.07 x 0.05 m, or 2.0 x 0.04 x 0.01 m to 3.0 x 0.05 x 0.03 m.

15. The cooling element according to claims 13 to 14, wherein the longitudinal direction of the steel insert (1) extends substantially perpendicularly to the channels (19) .

16. The cooling element according to claims 12 to 15, wherein the cooling element (17) comprises at least 5, or at least 10, or at least 15, or at least 20, or at least 25, or at least 30 steel inserts (1) .

17. The cooling element according to claim 16, wherein the steel inserts (1) create a lamellar structure on cooling element (17) .

18. The cooling element according to claim 17, wherein the distance between the longitudinal directions of the steel inserts (1) in the lamellar structure is at least 0.001 m, or 0.002 m, or 0.003 m, or 0.004, or 0.005 m.

19. The cooling element according to any of claims 17 to 18, wherein the steel inserts (1) in the lamellar structure are arranged such that gaps are created between the steel inserts (1) .

20. A method for generating an autogenous protective layer on an inner surface (2) of a furnace having an inner surface (2) according to claim 1, the method comprising capturing melted or solid particles present in the furnace during operation, wherein the melted or solid particles are captured on the at least one steel insert ( 1 ) .

21. Use of the furnace according to claim 1, or use of the cooling element according to claim 12 in a furnace, in a direct iron reduction process, electric smelting process, electric reduction process, flash smelting process, flash converting process, bath smelting process or bath converting process.

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