Refractory lining

Abstract

The present invention relates to a precast ring for use in a furnace, a refractory lining comprising a precast ring and a dry vibration material and a method of forming a refractory lining.

Description

[0001] Refractory Lining

[0002] FIELD OF THE INVENTION

[0003]

[0001] The present invention relates to a precast ring for use in a furnace, a refractory lining comprising a precast ring and a dry vibration material, and a method of forming a refractory lining.

[0004] BACKGROUND OF THE INVENTION

[0005]

[0002] Various types of refractory linings are known that are used in the operation of furnaces. The refractory linings are required to be mechanically stable and capable of withstanding the harsh conditions in a furnace. This poses many challenges including maintaining the integrity of the refractory lining for effective and safe operation. For example, it is often the case that the refractory lining at the top of the furnace exhibits lower strength and is susceptible to crumbling or cracking. Such issues not only necessitate frequent repairs and / or replacements, but such defects in the refractory lining can also pose safety risks and could even lead to explosions.

[0006]

[0003] In order to form a mechanically sound refractory lining, a variety of materials are used in the compositions of the lining. However, some of the materials used may be toxic. For example, materials containing boron can be detrimental to the environment. This has become an increasing problem in the industry due to the introduction of ever more stringent environmental regulations. Additionally, the energy consumption of furnaces is under scrutiny, requiring the development of more energy efficient systems.

[0004] The installation process for refractory linings is also time consuming, often resulting in extended downtime for the furnace. Considering all these factors, efficiently operating furnaces whilst ensuring safety and compliance with market demands is becoming increasingly challenging.

[0007]

[0005] Therefore, there is a need to provide an improved way of operating a furnace to address the current challenges.

[0008] SUMMARY OF THE INVENTION

[0009]

[0006] The present invention is defined in the appended claims.

[0010]

[0007] In accordance with a first aspect, there is provided a precast ring (1) wherein the ring (1) comprises a protrusion (2) on the bottom surface of the ring (3) for use in a furnace.

[0008] In accordance with a second aspect, there is provided a refractory lining comprising a precast ring (1) according to the first aspect and a dry vibration material.

[0009] In accordance with a third aspect, there is provided a method of forming a refractory lining according to the second aspect, comprising:

[0011] - forming a wall lining with a dry vibration material composition of up to about 85% of the total height of the furnace wall followed by vibrating; adding dry vibration material composition on top of the wall lining; placing the precast ring on the dry vibration material composition and filling any gaps behind the precast ring with more dry vibration material composition, followed by vibrating and sintering.

[0012]

[0010] In accordance with a fourth aspect, there is provided a use of a precast ring according to the first aspect as refractory lining.

[0013]

[0011] In accordance with a fifth aspect, there is provided a kit comprising a precast ring according to the first aspect and a dry vibration material.

[0014]

[0012] Certain embodiments of the present invention may provide one or more of the following advantages:

[0015] • ease of installation and formation of refractory lining;

[0016] • simplified installation and formation of refractory lining;

[0017] • elimination of the need for sintering the top ring;

[0018] • elimination of the need for sintering the top ring on site;

[0019] • time saving method of installing the refractory lining;

[0020] • time saving method of installing the refractory lining on site;

[0021] • good and / or enhanced mechanical strength of precast ring and subsequent refractory lining;

[0022] • improved safety when using the precast ring in a furnace;

[0023] • prevention of leakage out of the furnace when using the precast ring;

[0024] • reduced risk of accidents and / or explosions in furnace operations;

[0025] • optimised application of dry vibration material in refractory lining;

[0026] • precast ring able to withstand abrasive action, such as cleaning;

[0027] • precast ring able to withstand mechanical wear, such as when charging;

[0028] • application of a precast ring to reduce the down time of the furnace;

[0029] • mitigating and / or hindering iron penetration at the most exposed areas;

[0030] • precast ring that counteracts slag attack; • increased mechanical lifetime of the furnace;

[0031] • enhanced durability of the refractory lining within the furnace;

[0032] • ability to use furnaces with refractory linings comprising boron free dry vibration material;

[0033] • compatibility of furnaces with refractory linings made from boron free dry vibration material and

[0034] • desired reduced environmental impact due to, for example, reducing or eliminating the use of boron and increased lifetime and efficiency of furnace.

[0035]

[0013] The details, examples and preferences provided in relation to any particular one or more of the stated aspects of the present invention apply equally to all aspects of the present invention. Any combination of the embodiments, examples and preferences described herein in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein, or otherwise clearly contradicted by context.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037]

[0014] The invention will further be illustrated by reference to the following figures: Fig. 1 Schematic of furnace with the precast ring (1) and dry vibrational material (7);

[0038] Fig. 2 Cross-section of precast ring (1) showing the protruding portion (2) of the bottom surface (3) of the ring;

[0039] Fig. 3 Schematic of the ring (1) showing the bottom surface (3) (not visible in Figure), the top surface (5), the recesses (4) and the attachment portions (6);

[0040] Fig. 4 Schematic of the ring (1) showing the bottom surface (3), the top surface (5) (not visible in Figure), the recesses (4), the attachment portions (6) and the protruding portion (2);

[0041]

[0015] It is understood that the following description and references to the figures concern exemplary embodiments of the present invention and shall not be limiting the scope of the claims.

[0042] DETAILED DESCRIPTION

[0043]

[0016] The present invention is based on the surprising finding that the use of a precast ring can improve the safety and usability of furnaces. The present invention can provide many benefits to the operation of furnaces, in particular electric furnaces, such as core induction furnaces (CIF). These operational benefits are evident when the furnace is equipped with various refractory linings, such as refractory linings comprising a dry vibration material (DVM).

[0044]

[0017] The precast ring according to the invention can be manufactured off-site and subsequently installed in the furnace on-site. An improvement of efficiency when operating furnaces can be observed by using this route. The precast ring can be prefabricated by a process involving casting, delivered to site and installed in the furnace by vibrating the ring with the dry vibration material composition to form the refractory lining. The precast ring can be custom-made to order to fit the specific dimensions of a specific furnace. The precast ring is intended for integration with the refractory lining, which is made of dry vibration material. The precast ring is installed to form part of the refractory lining by vibrating the precast ring into place and is in direct contact with the dry vibration material. The installation results in a refractory lining with good mechanical properties, which is, in part, achieved by the protrusion on the bottom surface of the precast ring which allows intimate contact and integration between the precast ring and the surrounding dry vibration material. The precast ring of the present invention is not placed on a further precast ring in the furnace. The protrusion on the bottom surface of the ring is not intended to slot into a cavity of a further precast ring to form the furnace lining. In some embodiments, the furnace lining comprises a single precast ring according to the invention. The furnace lining of the present invention comprises one precast ring and a dry vibration material.

[0045]

[0018] The method of installation described herein may form a seamless, or near seamless, joint in the refractory lining contributing to a refractory lining with good mechanical properties. Without wishing to be bound by theory, it is considered that the formation of a seamless, or near seamless, joint according to the invention helps prevent leakage before, during and / or after the furnace is operation. This may also contribute to increasing the safety of operating the furnace.

[0046]

[0019] The precast ring can be used in a range of furnaces, such as coreless induction furnaces. In some examples the furnace according to the present invention heats materials to a temperature of up to about 1700°C, for example from about 1150°C to about 1700°C. Examples of materials heated in the said furnace include iron, grey iron, steel.

[0047]

[0020] The precast ring comprises a protruding portion on the bottom surface of the ring. The schematic in Fig.1 shown an example of a refractory, wherein the precast ring (1) is arranged on top of the dry vibration material (7) to form the refractory lining. The protrusion is an integral part of the precast ring and forms a thinner edge extending away from the ring (see e.g. Fig 2). The protruding portion may have one or more ridges, tapered portions and / or projecting portions. A protruding portion of this shape can be utilised to form part of a refractory lining in combination with a refractory material such as dry vibration material. In some embodiments the protruding portion is entirely encased in dry vibration material and forms a compacted connection. In some examples the protruding portion can form an airtight bond with the dry vibration material to form the refractory lining. An “airtight bond” as used herein refers to a compacted bond where large air pockets have been mechanically eliminated. However, this bond is not formed under vacuum conditions and remains air permeable. The presence of a protruding portion on the bottom surface of the ring establishes a path from the inside of the furnace to outside the furnace that is longer than a direct path, i.e. a straight path from the inside of the furnace to the outside of the furnace. The protruding portion increases the distance required for any material moving from inside the furnace to outside the furnace, thereby impeding the direction of movement of materials from inside the furnace to outside the furnace. In this way, the sealing properties can be enhanced, contributing to the overall strength of the refractory lining. Such an interface with a protruding portion for use with dry vibration material increases the barrier for leakage, especially when compared to the straight line connections formed, for example, when one precast ring is arranged on top of a second precast ring.

[0048]

[0021] The precast ring can form the upper part of the refractory lining that is in close proximity to the lid of the furnace. The use of a precast ring in this position may enhance the overall strength of the refractory lining, especially as this part of the furnace is often prone to weaknesses in the refractory lining when using known methods. Any increase in overall strength of the refractory lining contributes to safer furnace operations.

[0049]

[0022] The top section of the precast ring may comprise at least one recessed portion, such as two recessed portions or three recessed portions, whereby a section of the ring is absent, recessed, indented and / or cut out. The at least one recessed portion may be any shape, such as rectangular or circular. Such recessed portions can be tailored to a particular furnace allowing for unobstructed functionality. For example, a recessed portion can allow space for the spout of the furnace. In some examples, the recessed portions may align flush with the one or more spout(s) of the furnace.

[0050]

[0023] In some embodiments the recessed portion comprises a precast spout in the recessed portion. The presence of a precast spout in the precast ring allows convenient use of the furnace whilst minimizing spillage. The precast spout is flush with the top of precast ring and can be tailored to the use of a specific furnace. The precast spout on the precast ring results in a strong and robust structure.

[0051]

[0024] In some embodiments, the at least one recessed portion is at least partially chamfered, such as stepped or tiered. The recessed portion may be slanted. Without wishing to be bound by theory, it is considered that the shape of the recessed portion in this way helps avoid leakage out of the furnace and therefore contributes to the overall safety of operating the furnace.

[0052]

[0025] In some embodiments the top surface of the ring comprises two or more attachment units. For example, the top surface of the ring may comprise three or more attachment units, such as three attachments units, or four attachments units, or five attachments units, or six attachments units, or seven attachment units. The attached units may be, for example, hooks or eyelets. The attachment units may be utilised to lower the ring into the furnace. The number of attachment units required is expected to be greater for larger structures. In some examples, a minimum of three attachments units are required to securely lower the ring into the furnace.

[0053]

[0026] In some embodiments, the precast ring has an inner diameter of from about 0.5 m (meters) to about 4.0 m (meters), for example from about 0.6 m to about 3.8 m, or from about 0.8 m to about 3.6 m, or from about 1.0 m to about 3.4 m, or from about 1.2 m to about 3.2 m, or from about 1.4 m to about 3.0 m, or from about 1.6 m to about 2.8 m, or from about 1.8 m to about 2.6 m, or from about 2.0 m to about 2.4 m.

[0054]

[0027] In some embodiments, the precast ring has a total height from the bottom surface of the ring to the top surface of the ring of from about 300 mm to about 1500 mm, for example, from about 350 mm to about 1450 mm, or from about 400 mm to about 1400 mm, or from about 500 mm to about 1300 mm, or from about 600 mm to about 1200 mm, or from about 700 mm to about 1000 mm, or from about 800 mm to about 900 mm.

[0055]

[0028] In some embodiments, the precast ring has a recessed portion with a height of from about 50 mm to about 1450 mm, for example, from about 100 mm to about 1400 mm, or from about 150 mm to about 1300 mm, or from about 200 mm to about 1200 mm, or from about 300 mm to about 1100 mm, or from about 400 mm to about 1000 mm, or from about 500 mm to about 800 mm, or from about 600 mm to about 700 mm.

[0056]

[0029] In some embodiments the precast ring comprises the refractory material in an amount of at least about 70 wt.% based on the total weight of the precast ring, for example, at least about 75 wt.%, or at least about 80 wt.%, or at least about 85 wt.%, or at least about 90 wt.%, or at least about 95 wt.%, or at least about 98%, or at least about 99 wt.%, based on the total weight of the precast ring. In some embodiments, the refractory material of the precast ring is selected from andalusite, bauxite, chamotte, mullite, brown fused alumina, tabular alumina, white fused alumina, corundum and combinations thereof.

[0057]

[0030] In some embodiments the precast ring comprises the fibres in an amount of at least about 30 wt.% based on the total weight of the precast ring, for example, at least about 25 wt.%, or at least about 20 wt.%, or at least about 15 wt.%, or at least about 10 wt.%, or at least about 5 wt.%, or at least about 2%, or at least about 1 wt.%, based on the total weight of the precast ring. In some embodiments the top section of the precast ring comprises more fibres than the bottom section of the precast ring. In some embodiments the fibres are selected from metal fibres, mineral fibres plastic fibres and combinations thereof. In some embodiments the metal fibres comprise steel and / or tungsten.

[0058]

[0031] In some embodiments, the precast ring has a smooth surface. Such a smooth surface can have operational advantages, such as the reduction of unwanted material such as slag sticking to the surface.

[0059]

[0032] A refractory lining according to the present disclosure may comprise a precast ring and a dry vibration material. In some embodiments the dry vibration material is boron free. Using boron free material in this way can reduce the environmental impact and / or simplify regulatory compliance. Any known dry vibration material can be used with the precast ring to form a refractory lining. For example, the dry vibration material may be selected from silica raw materials, such as quartzite and / or fused silica; alumina raw material, such as brown fused alumina and / or white fused alumina; spinel; silicon carbide and combinations thereof.

[0060]

[0033] The refractory lining covers the inside of a furnace wall. The refractory lining is the interior facing layer of the furnace wall and is in direct contact with the process environment, e.g. molten metal, hot gases and slag. The refractory lining serves as the first line of defence against thermal and chemical wear and covers the entire inner surface of the furnace wall.

[0061]

[0034] In some embodiments the precast ring makes up between about 15% to about 30% of the of the total height of the furnace wall. For example, the precast ring makes up about 20%, or up to about 22 %, or up to about 25% or up to about 28% the height of the furnace wall.

[0062]

[0035] A method of forming a refractory may comprise driving the precast ring into the dry vibration material refractory wall by about between about 10 mm to 80 mm. For example, the precast ring may be driven into the dry vibration material by about 15 mm, or about 20 mm, or about 25 mm, or about 30 mm, or about 35 mm, or about 40 mm, or about 45 mm, or about 50 mm, or about 55 mm, or about 60 mm, or about 65 mm, or about 70 mm, or about 75 mm.

[0063]

[0036] The “dry vibration material composition” as used herein refers to a flowable or free-flowing dry or semi-dry particulate material that can be compacted for use in refractory applications. The dry vibration material composition used in the method has not been sintered and may be a loose material that this able to move freely and can fill up any gaps that are present. This dry vibration material composition is then compacted by vibration as part of the method according to the invention. Once compacted and sintered, the dry vibration material composition is no longer a loose, free flowing material. The compacted dry vibration material composition is referred to herein as “dry vibration material”. The dry vibration material may comprise some residual uncompacted dry vibration material. In some examples, dry vibration material comprises up to 10% by weight of dry vibration material composition, based on the total weight of the dry vibration material.

[0064]

[0037] In some embodiments the method causes the precast ring to be driven into the dry vibration material. This can occur by gravitational forces, aided by the vibration and / or pushed down mechanically. In some examples, vibrational equipment is used in the method to form the refractory lining. Any suitable vibration equipment may be used in the claimed method, including bottom plate vibrators and wall vibrators. In some examples, Klein vibrating systems may be used, such as a bottom plate vibrator, a bottom jolter plate, and / or an automatic 3-arm walljolter with lifting device.

[0065]

[0038] In some embodiments a seal is installed after the precast ring is installed. This seal may serve to hold the materials within the refractory lining in place and may sit between the precast ring and the refractory wall. In some examples the seal is made of plastic or ramming material. In one example the seal is CALDE®RAM PB89.

[0066]

[0039] The present disclosure may be described by one or more of the following paragraphs:

[0067] A. A precast ring (1), wherein the ring (1) comprises a protruding portion (2) on the bottom surface (3) of the ring (1) for use in a furnace.

[0068] B. The precast ring (1) according to paragraph A, wherein the top section of the ring comprises at least one recessed portion (4).

[0069] C. The precast ring (1) according to any one of the preceding paragraphs wherein the at least one recessed portion (4) is at least partially chamfered.

[0070] D. The precast ring (1) according to any one of the preceding paragraphs wherein the top surface (5) of the ring (1) comprises two or more attachment units (6).

[0071] E. The precast ring (1) according to any one of the preceding paragraphs, wherein the inner diameter of the ring (1) is from about 0.5 m to about 4.0 m.

[0072] F. The precast ring (1) according to any one of the preceding paragraphs, wherein the total height of the ring (1) from the bottom surface (3) of the ring to the top surface (5) of the ring is from about 300 mm to about 1500 mm.

[0073] G. The precast ring (1) according to any one of the preceding paragraphs, wherein the recessed portion (4) has a height of from about 50 mm to about 1450 mm.

[0074] H. The precast ring (1) according to any one of the preceding paragraphs, wherein the ring (1) comprises a refractory material. I. The precast ring (1) according to paragraph H, wherein the refractory material is present in an amount of at least 70 wt.% based on the total weight of the precast ring.

[0075] J. The precast ring (1) according to any one of the preceding paragraphs, wherein the ring (1) comprises fibres.

[0076] K. The precast ring (1) according to paragraph J, wherein the fibres are selected from metal fibres, mineral fibres and / or plastic fibres.

[0077] L. The precast ring (1) according to paragraph J, wherein the metal fibres comprise steel and / or tungsten.

[0078] M. The precast ring (1) according to any one of paragraphs J to L, wherein the fibres make up at least about 30 wt.% based on the total weight of the precast ring.

[0079] N. A refractory lining comprising a precast ring (1) according to any one of paragraphs A to M and a dry vibration material.

[0080] O. The refractory lining according to paragraph N, wherein the dry vibration material is boron free.

[0081] P. The refractory lining according to paragraph N or paragraph O, wherein the refractory lining covers the inside of a furnace wall.

[0082] Q. The refractory lining according to any one of paragraph N to paragraph P, wherein the precast ring is from about 15% to about 30% of the total height of the furnace wall.

[0083] R. A method of forming a refractory lining according to any one of paragraphs N to Q, comprising:

[0084] - forming a wall lining with a dry vibration material composition of up to about 85% of the total height of the furnace wall, followed by vibrating; adding dry vibration material composition on top of the wall lining; placing the precast ring on the dry vibration material composition and filling any gaps between the precast ring and the furnace with more dry vibration material composition, followed by vibrating and sintering.

[0085] S. The method of paragraph R, wherein the precast ring is driven into the dry vibration material by between about 10 mm to 80 mm.

[0086] T. Use of a precast ring (1) according to any one of paragraphs A to M as a part of a refractory lining.

[0087] U. A kit comprising a precast ring (1) according to any one of paragraphs A to M and a dry vibration material.

[0088] REFERENCE SIGNS

[0089] 1. Precast ring

[0090] 2. Protruding portion

[0091] 3. Bottom surface

[0092] 4. Recessed portion

[0093] 5. Top surface

[0094] 6. Attachment Unit

[0095] 7. Dry vibration material

Claims

CLAIMS1. A precast ring (1), wherein the ring (1) comprises a protruding portion (2) on the bottom surface (3) of the ring (1) for use in a furnace.

2. The precast ring (1) according to claim 1, wherein the top section of the ring comprises at least one recessed portion (4), optionally wherein the at least one recessed portion (4) is at least partially chamfered.

3. The precast ring (1) according to any preceding claim wherein the top surface (5) of the ring (1) comprises two or more attachment units (6).

4. The precast ring (1) according to any preceding claim, wherein the inner diameter of the ring (1) is from about 0.5 m to about 4.0 m and / or wherein the total height of the ring (1) from the bottom surface (3) of the ring to the top surface (5) of the ring is from about 300 mm to about 1500 mm.

5. The precast ring (1) according to any preceding claim, wherein the recessed portion (4) has a height of from about 50 mm to about 1450 mm.

6. The precast ring (1) according to any preceding claim, wherein the ring (1) comprises a refractory material, wherein the refractory material is optionally present in an amount of at least 70 wt.% based on the total weight of the precast ring.

7. The precast ring (1) according to any preceding claim, wherein the ring (1) comprises fibres, wherein the fibres are optionally selected from metal fibres, mineral fibres and / or plastic fibres.

8. The precast ring (1) according to claim 7, wherein the fibres make up at least about 30 wt.% based on the total weight of the precast ring.

9. A refractory lining comprising a precast ring (1) according to any one of claims 1 to 8 and a dry vibration material.

10. The refractory lining according to claim 9, wherein the dry vibration material is boron free.

11. The refractory lining according to claim 9 or claim 10, wherein the refractory lining covers the inside of a furnace wall and / or wherein the precast ring is from about 15% to about 30% of the total height of the furnace wall.

12. A method of forming a refractory lining according to any one of claims 9 to 11 , comprising:- forming a wall lining with a dry vibration material composition of up to about 85% of the total height of the furnace wall, followed by vibrating; adding dry vibration material composition on top of the wall lining; placing the precast ring on the dry vibration material composition and filling any gaps between the precast ring and the furnace with more dry vibration material composition, followed by vibrating and sintering.

13. The method of claim 12, wherein the precast ring is driven into the dry vibration material by between about 10 mm to 80 mm.

14. Use of a precast ring (1) according to any one of claims 1 to 8 as a part of a refractory lining.

15. A kit comprising a precast ring (1) according to any one of claims 1 to 8 and a dry vibration material.

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