GB2573331A

GB2573331A - Thermal processing apparatus

Info

Publication number: GB2573331A
Application number: GB1807344.5A
Authority: GB
Inventors: O'flynn Donal
Original assignee: Donal Oflynn
Current assignee: Donal Oflynn
Priority date: 2018-05-04
Filing date: 2018-05-04
Publication date: 2019-11-06
Also published as: GB201807344D0

Abstract

Thermal processing apparatus 1 comprises a containment vessel 2 which provides a controlled atmosphere or vacuum. The containment vessel contains an elongate path 5 in gaseous communication with the containment vessel. The path 5 consists of path segments 8 joined together by support segments 9. Radiation emitters 12 heat process material 3 within at least a portion of the path using radiation 13. The path segments 8 comprise a material which is transparent to radiation within a bandwidth emitted by the emitters. The emitters may be microwave emitters. A helical screw (17, Fig. 16) may move material along the path and provide additional heating. Vibrational exciters (39, Fig 18) may be attached to the path segments or support segments. Additional process materials may be introduced at intermediate inlets (38, Fig. 17). A method of processing material is also claimed, which may comprise calcination, thermal desorption, sintering, agglomerating, reduction roasting, drying, or pelletizing the process material.

Description

Thermal processing apparatus

Field of the invention

The present invention relates to apparatus and methods for thermal processing of materials.

Background

Thermal processing of materials is an established method for processes such as, for example, calcination, thermal desorption, sintering, drying, pelletization, and so forth.

Rotary kilns represent a commonly used apparatus for thermal processing of materials. Rotary kilns typically include a long cylindrical processing vessel which is rotatably mounted by means of a number of riding rings and trunnion bases. Rotary kilns are typically heated using combustion flames within the processing vessel, or using combustion flames or other heating systems provided outside the processing vessel.

Other types of apparatus for thermal processing have been reported. For example, Buttress et. al, “Towards large scale microwave treatment of ores: Part 1 - Basis of design, construction and commissioning”, Minerals Engineering 109 (2017), pages 169 20 to 183, describes a system for the microwave treatment of ores which is reported to be capable of operating at throughputs of up to 150 tonnes per hour. The authors describe confining the electric field produced from two too kW generators operating at 896 MHz in a gravity fed vertical flow system using circular choking structures yielding power densities of at least 6 x 10⁸ W.m-3 in the heated mineral phases. The described 25 system was used to treat a range of porphyry copper ores.

Summary

According to a first aspect of the invention there is provided thermal processing apparatus including a containment vessel for providing a controlled atmosphere or a 30 vacuum. The containment vessel is elongated in a first direction. The containment vessel contains a path for process materials. The path is elongated in the first direction and is defined by a plurality of path segments which are jointed to one another by a plurality of support segments. The path is in gaseous communication with the rest of the containment vessel. The containment vessel also contains one or more radiation 35 emitters configured to heat process materials within at least a portion of the path using

- 2 radiation within a bandwidth. The path segments comprise a first material which transmits radiation within the bandwidth.

The path may extend between first and second ends of the containment vessel. Process materials may be introduced into the path at the first end and removed from the path at the second end. The path maybe inclined at an angle to the horizontal so that the first end is above the second end in order to permit gravitationally assisted flow of process materials along the path from the first to second ends. The angle may be up to 2 degrees, up to 3 degrees, up to 4 degrees, up to 5 degrees or up to ten degrees. The angle may be between 3 and 10 degrees. The angle may be up to 30 degrees, up to 45 degrees or up to 90 degrees. The path maybe oriented substantially vertically with respect to gravity. The thermal processing apparatus maybe configured so that the thermal processing apparatus does not rotate.

The containment vessel may include one or more inlets for introducing gasses into the containment vessel. Gasses introduced into the containment vessel may be inert gasses. The containment vessel may include one or more outlets for extracting gasses from the containment vessel. Gasses extracted from the containment vessel may include one or more of ambient air, gasses introduced through the inlets, gasses generated by the heating of process materials, and so forth.

By gaseous communication, it is meant that gases may be freely exchanged between the path and the rest of the containment vessel between the path and the interior walls of the containment vessel. For example, gaseous communication maybe provided by one 25 or more holes, vents or valves provided in one or more of the path segments. In this way, any transient pressure difference which is evolved between the path and the rest of the containment vessel may be rapidly equalised.

Gaseous communication between the path and the rest of the containment vessel may 30 be provided by at least one of the path segments including at least one venting hole.

Venting holes are preferably provided in regions of path segments which are configured to be arranged above the process materials in service, with respect to gravity.

Process materials maybe heated to a temperature within the range from 50 °C to

1900 °C, from too °C to 1900 °C, from 200 °C to 1900 °C, from 300 °C to 1900 °C, or from 500 °C to 1900 °C, inclusive of the endpoints.

-3The first material may transmit at least 50%, at least 60%, at least 70% or at least 80% of incident radiation within the bandwidth. The first material may have a peak transmission within the bandwidth of at least 50%, at least 60%, at least 70% or at least 5 80%.

At least some of the support segments may be connected to the containment vessel so as to suspend the path at a distance from the sides of the containment vessel.

The path may have a non-circular cross-section. The path cross-section may be triangular, square, pentagonal, hexagonal, or any other regular or irregular polygonal shape.

The path may have a shape and be formed of a first material such that if the path were 15 sealed, the path would be incapable of sustaining a pressure differential of more than

0.1 atmospheres, more than 0.2 atmospheres, or more than 0.5 atmospheres.

The one or more radiation emitters may comprise microwave emitters. The radiation emitters may take the form of microwave emitters. The radiation emitters may be 20 configured to irradiate the path from any direction. The one or more radiation emitters may be configured to heat process materials contained within at least a portion of the path according to a predetermined or dynamically programmable profile.

The path segments may comprise one or more plate-like path segments. The plate-like 25 path segments may be arranged such that the plane of the plate-like path segments is parallel to the first direction. Path segments may be jointed to one another in series in the first direction by respective longitudinal support segments. Plate-like path segments may be jointed to one another along edges parallel to the first direction by one or more edge support segments.

The radiation emitters may be directed along respective normals to one or more platelike path segments. A separate radiation emitter may be directed at each plate-like path segment.

-4An upper region of the path may be not enclosed along at least a portion of the length of the path. The upper region of the path may be defined with respect to gravity when the thermal processing apparatus is installed and in service.

The thermal processing apparatus may also include a helical screw enclosed within the path and configured to assist in moving process materials along the path. The helical screw maybe configured to cause mixing of process materials.

The helical screw may be heated. The helical screw may be heated using resistance 10 heating. The helical screw may be heated using inductive heating.

The first material forming the path segments maybe a refractory material. The first material may be aluminium oxynitride.

The support segments may be formed of a second material, wherein the second material may be a refractory material. The support segments may be formed by 3D printing.

The thermal processing apparatus may also include one or more additional material 20 inlets configured to introduce additional process materials at one or more intermediate positions between the first and second ends of the path.

The thermal processing apparatus may also include one or more vibrational exciters attached to one or more path segments and/or one or more support segments. The 25 vibrational exciters may be configured to vibrate the path in order to reduce or prevent process materials adhering to the path and/or development of stagnant regions of process materials within the path. Vibrational exciters may be piezoelectric actuators. Vibrational exciters maybe unbalanced rotating masses.

The containment vessel may be at least 50 cm in diameter, at least im in diameter, at least 2 m in diameter, at least 5mm diameter or at least 10 m in diameter. The length of the path may be at least 1 m, at least 10 m, at least 50 m or more than too m.

According to a second aspect of the invention, there is provided a method including introducing process materials into a first end of a path for the process materials. The path is elongated in a first direction and is defined by a plurality of path segments

-5which are jointed to one another by a plurality of support segments. The path is enclosed within a containment vessel for providing a controlled atmosphere or a vacuum. The path is in gaseous communication with the rest of the containment vessel. The method also includes heating process materials within at least a portion of the path 5 using radiation within a bandwidth. The path segments comprise a first material which transmits radiation within the bandwidth. The method also includes extracting process materials from a second end of the path.

The method may comprise calcination of process materials. The method may comprise 10 thermal desorption of one or more volatile substances present in process materials.

The method may comprise sintering process materials. The method may comprise agglomerating process materials. The method may comprise reduction roasting of process materials. The method may comprise drying process materials. The method may comprise pelletizing process materials.

Process materials may be cement, lime, alumina, or titanium oxide.

The method may be carried out using the thermal processing apparatus.

-6Brief Description of the Drawings

Certain embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure i is a side view of a first thermal processing apparatus;

Figure 2 is a cross-sectional view along the axial direction of the first thermal processing apparatus shown in Figure 1;

Figure 3 illustrates a square-sectioned path for a thermal processing apparatus; Figure 4 illustrates an octagonal-sectioned path for a thermal processing apparatus; Figures 5 and 6 illustrate a first longitudinal support segment for a thermal processing 10 apparatus;

Figures 7 and 8 illustrate a second longitudinal support segment for a thermal processing apparatus;

Figures 9 and 10 illustrate a third longitudinal support segment for a thermal processing apparatus;

Figure 11 illustrates a square-sectioned path for a thermal processing apparatus, formed by jointing plate-like path segments;

Figure 12 illustrates an octagonal-sectioned path for a thermal processing apparatus, formed by jointing plate-like path segments;

Figure 13 illustrates a partially enclosed path for a thermal processing apparatus;

Figures 14 and 15 illustrate assembling a square-sectioned path for a thermal processing apparatus using plate-like path segments and edge support segments; Figure 16 is a side view of a second thermal processing apparatus;

Figure 17 is a side view of a third thermal processing apparatus; and Figure 18 is a side view of a fourth thermal processing apparatus;

Detailed Description of Certain Embodiments

In the following, like parts are denoted by like reference numbers.

First thermal processing apparatus

Referring to Figure 1, a first thermal processing apparatus 1 is shown.

The first thermal processing apparatus 1 includes a containment vessel 2 configured for processing of process materials 3 in a controlled atmosphere or a vacuum, if required. The containment vessel 2 is elongated in a first, axial direction 4. The first thermal processing apparatus 1 also includes, within the containment vessel 2, a path (or conduit) 5 for containing the process materials 3. The path 5 (or conduit) is elongated

-7along the axial direction 4, and the first and second ends 6, 7 of the path typically coincide with the opposite ends of the containment vessel 2 in the axial direction. The path 5 is defined by a plurality of path segments 8 which are jointed to one another by a plurality of support segments 9. In some examples, a path segment 8 may take the form of one or plate-like or sheet-like path segments 23 (Figure 3). The path segments may be jointed in series along the axial direction 4 by longitudinal support segments

9. Additionally or alternatively, path segments 8 formed from plate-like path segments 23 (Figure 3) may be jointed along edges parallel to the axial direction 4 by edge support segments 24 (Figure 11).

The process materials 3 are typically in the form of powdered, granulated, pelletized, fragmented or agglomerated materials. The process materials 3 maybe substantially a single substance or compound, or maybe a mixture or blend of multiple substances and/or compounds.

The path 5 is in gaseous communication 10 with the rest of the containment vessel 2.

By gaseous communication 10, it is meant that gases may be freely exchanged between the path 5 and the rest of the containment vessel 2 between the path 5 and the interior walls of the containment vessel 2. For example, gaseous communication 10 maybe 20 provided by one or more holes, vents or valves provided in one or more of the path segments 8. In this way, any transient pressure differential which is evolved between the path 5 and the rest of the containment vessel 2 maybe rapidly equalised.

For example, gaseous communication 10 between the path 5 and the rest of the containment vessel 2 may be provided by at least one of the path segments 8 including at least one venting hole 11. Venting holes 11 are preferably provided in portions of path segments 8 which will be arranged above the process materials 3 with respect to gravity when the apparatus 1 is installed and in use.

The first thermal processing apparatus 1 also includes, contained within the containment vessel 2, one or more radiation emitters 12 configured to heat the process materials 3 within at least a portion of the path 5 using radiation 13 having wavelength(s) within a bandwidth Δλ. The one or more radiation emitters 12 may comprise or consist of emitters configured to generate radiation 13 in a microwave band, an infrared band, a visible band and so forth. For example, the radiation emitters may take the form of microwave emitters.

-8The path segments 8 comprise or consist of a material which substantially transmits radiation 13 within the bandwidth Δλ. For example, the material forming the path segments 8 may transmit at least 50%, at least 60%, at least 70% or at least 80% of 5 incident radiation within the bandwidth Δλ. Additionally or alternatively, the material forming the path segments 8 may have a peak transmission within the bandwidth Δλ of at least 50%, at least 60%, at least 70% or at least 80%.

Radiation emitters 12, in combination with path segments 8 which substantially transmit the radiation 13, may provide a more controllable and efficient heating than, for example, the combustion flames or external heating elements employed in many conventional rotary kiln systems. Radiation emitters 12 may also provide a more efficient heating of the process materials 3, since by tuning the radiation 13 bandwidth Δλ to an absorbance of the process materials 3, selective or substantially selective heating of the process materials 3 may be provided.

The process materials 3 are introduced into the path 5 through a material inlet 14 at the first end 6, and removed from the path 5 through a material outlet 15 formed at the second end 7. When installed and in use, the path 5 may be inclined at an angle Θ to the 20 horizontal 16 so that the first end 6 is above the second end 7 in order to permit gravitational flow of process materials 3 along the path 5 from the first to second ends

6, 7. For example, the angle Θ may be up to 2 degrees, up to 3 degrees, up to 4 degrees, up to 5 degrees or up to ten degrees. For some applications, the angle θ maybe between 3 and 10 degrees. In further examples, the angle θ may be up to 30 degrees or up to 45 degrees. In certain examples, the angle θ may be up to 90 degrees so that the path 5 extends substantially vertically. The flow of process materials 3 along the path 5 maybe maintained by a combination of removing processed process materials 3 through the material outlet 15 and the addition of unprocessed process material 3 through the material inlet 15. The process materials 3 may progress along the path 5 by rolling, sliding, falling or a combination thereof. Additionally or alternatively, movement of process materials 3 along the path 5 maybe assisted by a helical screw 17 (Figure 16) arranged within the path 5 and rotating about the axial direction 4.

Unlike conventional rotary kilns used for thermal processing, the first thermal processing apparatus 1 is configured so that the first thermal processing apparatus 1 does not rotate in use. Instead, the first thermal processing apparatus 1 remains in a

-9fixed orientation in use. This may provide advantageous effects such as reducing wear and avoiding the need for high load rolling bearings.

The containment vessel 2 may include one or more gas inlets 18 for introducing gasses

19 into the containment vessel. Gasses 19 introduced into the containment vessel 2 may be inert gasses such as, for example, argon or nitrogen. Although a single gas inlet 18 is shown in Figure 1, two or more gas inlets 18 may be spaced along the length of the containment vessel 2. Additionally or alternatively, gasses 19 may be introduced through the material inlet 14 or outlet 15.

The containment vessel 2 may include one or more outlets 20 for extracting gasses 21 from the containment vessel 2. Gasses 21 extracted from the containment vessel 2 may include one or more of ambient air, gasses introduced through one or more inlets 18, gasses generated from chemical reactions of the process materials 3 or vaporisation of 15 volatile components within the process materials 3, and so forth. Although a single gas outlet 20 is shown in Figure 1, two or more gas outlets 20 may be spaced along the length of the containment vessel 2. Additionally or alternatively, gasses 21 may be extracted through the material inlet 14 or outlet 15. In some examples, gas outlets 20 and/or venting holes 11 maybe provided at intervals along the path 5 and containment 20 vessel 2, in order to permit the escape of gasses released from the process materials 3 and prevent such gasses from building up within the path 5 or the containment vessel 2.

Through use of the gas inlets 19 and outlets 20, a controlled atmosphere may be sustained within the containment vessel 2 during processing of the process materials 3. For example, inert atmospheres of argon or nitrogen, or vacuum conditions, maybe used. The provision of gaseous communication 10 between the path 5 and the rest of the containment vessel 2 may avoid or reduce pressure differential forces acting on the path segments 8 and support segments 9. This enables the path 5 containing the materials to be produced from materials which would be unsuitable for sustaining pressure loads, for example many ceramic materials, whilst still permitting processing in a controlled atmosphere which maybe at a pressure differential compared to ambient atmosphere. Additionally, the absence of pressure differential forces acting on the path 5 also enables the use of path segments 8 having non-cylindrical geometries (Figure 3), which may be simpler to fabricate. In the first thermal processing apparatus

- 10 1, the containment vessel 2 bears any pressure differential loads developed between a controlled atmosphere used for thermal processing and the ambient atmosphere.

Further, because the path 5 need not contact the containment vessel 2 walls and because the process materials 3 are directly heated by the radiation 13, the containment vessel 2 walls may be at a substantially lower temperature than the processed materials 3. The first thermal processing apparatus 1 may enable, for example, high temperature controlled atmosphere processing using ceramic materials for the path segments 8 and support segments 9 which contact or may contact the processed materials 3, whilst using carbon steel for the containment vessel 2. Ceramics materials typically exhibit good mechanical properties such as strength and creep resistance at elevated temperatures. By contrast, carbon steels may undergo accelerated microstructural coarsening and associated loss of initial mechanical properties at elevated temperatures. If the process materials 3 directly contacted the containment vessel 2, then use of expensive high temperature steels, for example secondary hardened steels, might be required in order to sustain pressure differential forces over prolonged periods. Additionally, using ceramic materials to define the path 5 may provide further advantages such as a reduction in unwanted chemistries (many ceramics comprise chemically stable oxides) and/or reduced adhesion between the process materials 3 and 20 the path segments 8 and/or support segments 9.

Additionally or alternatively to the function of maintaining a controlled atmosphere, gasses 19, 21 may be flowed between gas inlets 18 and outlets 20, or between the material inlet 14 and outlet 15, in volumes and/or at velocities which may improve the 25 flow and/or mixing of process materials 3.

The process materials 3 may be heated to temperatures within a range from 50 °C to 1900 °C. Depending upon the application, the radiation emitters 12 may be configured to heat the process materials 3 substantially uniformly along the length of the path 5 30 between the first and second ends 6, 7. Alternatively, multiple radiation emitters 12 spaced along the path 5 may enable configurations in which the processed materials 3 contained within at least a portion of the path 5 are heated variably according to a predetermined or dynamically programmable temperature gradient profile along the path 5.

- 11 Referring also to Figure 2, a cross-section of the thermal processing apparatus i along the axial direction 4 is shown.

Although in Figure 1 the radiation emitters 12 have been illustrated as being arranged above the path 5 and the process materials 3, this need not be the case. Additionally, or alternatively, radiation emitters 12 may be configured to irradiate the path 5 from any direction and/or from multiple directions at once. For example, radiation emitters 12 maybe provided above, below and/or to either side of the path 5, with respect to gravity when the thermal processing apparatus 1 is installed and in use. Alternatively, radiation emitters 12 may be provided at intermediate positions such as, for example, to irradiate the path from an angle of 30 degrees to the vertical (with respect to gravity), and so forth.

As mentioned hereinbefore, the path 5 need not be touching or resting directly on any surface of the containment vessel 2. Preferably, some or all of the support segments 9 include one or more protrusions 22 which serve to support or suspend the path 5 at a distance from the interior walls of the containment vessel 2. The protrusions 22 may simply rest on a lower surface of the interior wall of the containment vessel 2, or the protrusions 22 may be joined, attached or otherwise secured to the interior wall of the containment vessel 2. The protrusions 22 may be integrally formed as part of corresponding support segments 9, or the protrusions 22 may be separate from, but joined to, the corresponding support segments 9. Preferably, the support segments 9 and any associated protrusions 22 are formed of materials having low thermal conductance, so as to maximise a temperature difference AT between the path 5 and process materials 3 contained therein, and the containment vessel 2 walls. The temperature difference AT may be increased further by processing in a vacuum or reduced pressure atmosphere to reduce or eliminate convective heat transport.

In some examples, the containment vessel 2 may range from several metres in length to several tens of metres in length. For example, the length of the path 5 within the containment vessel 2 maybe at least 1 m, at least 10 m, or at least 50 m. In other applications, the containment vessel 2 may be more than one hundred metres in length. The containment vessel 2 may be from tens of centimetres up to several meters in diameter. For example, the containment vessel 2 maybe at least 50 cm in diameter, at least 1 m in diameter, at least 2 m in diameter, at least 5 m in diameter or at least 10 m in diameter. The thermal processing apparatus 1 may be configured to handle from

- 12 several kilograms of process materials 3 per hour up to several tens, hundreds or even thousands of tonnes of process materials per hour, depending on the scale of the containment vessel 2 and the path 5.

For high temperature processing, the material forming the path segments 8 may be a refractory material such as, for example, aluminium oxynitride, alumina, magnesium oxide and so forth. Similarly, for high temperature processing, the support segments 9 maybe formed of a second material which is a refractory material. In some examples the path segments 8 and support segments 9 maybe formed from substantially the same materials. When the path segments 8 and support segments 9 are formed of the same material, they may still differ in other properties such as, for example, purity, porosity, surface roughness, grain size and so forth. For example, the path segments 8 and support segments 9 may both be formed of the same material, but the path segments 8 may require a smoother surface to promote sliding of process materials 3.

In some examples, the support segments 9 may be formed by 3D printing methods. Ceramic support segments 9 may be produced using granular ceramic 3D printing methods, for example printing a glue or binder to adhere ceramic particles together, followed by firing to sinter the particles.

In general, a method of processing process materials 3 using the apparatus 1 includes introducing the process materials 3 into the first end 6 of the path 5, heating the process materials 3 within at least a portion of the path 5 using radiation 13 within the bandwidth Δλ and supplied from the radiation emitters 12, and once the process materials 3 have traversed the path 5, extracting the processed process materials 3 from the second end 7 of the path 5.

The method may comprise one or more of calcination of the process materials 3, thermal desorption of one or more volatile substances present in the process materials

3, agglomerating the process materials 3, reduction roasting of the process materials 3, drying the process materials 3, pelletizing the process materials, and so forth. The process materials 3 may be cement, lime, alumina, titanium oxide and so forth.

Although the path segments 8 have been shown in Figure 2 as being cylindrical and concentric with the containment vessel 2, this is not essential for the first thermal processing apparatus 1. For example, the path 5 need not be arranged at the centre of

-13the containment vessel 2. Similarly, the path segments 8 need not be cylindrical and may have other, non-circular cross-sections. For example, the path 5 cross-section may be triangular, square, pentagonal, hexagonal, or any other regular or irregular polygonal shape.

Referring also to Figure 3 a square-sectioned path segment 8b is shown.

The square-section path segment 8b takes the form of four flat plate-like or sheet-like path segments 23 arranged to form the four sides of a square and bonded or joined 10 along the edges running parallel to the axial direction 4. The plate-like path segments forming a square-section path segment 8b maybe separate plate-like path segments which are subsequently]oined together by, for example, cement, adhesive, soldering, sintering or other material bonding processes suitable for the materials of the plate-like path segments 23. Advantageously, plate-like path segments 23 forming 15 a square-section path segment 8b may be jointed using edge support segments 24 (Figure 11). Alternatively, a square-sectioned path segment 8b maybe integrally formed as a single tubular segment having a square cross-section.

Referring also to Figure 4, an octagonal-sectioned path segment 8c is shown.

In this way, the path 5 may have a cross-sectional shape, for example square, and be formed of materials, for example ceramics, which would be incapable of sustaining any significant pressure differential loads. In the thermal processing apparatus 1 this is not a problem, because the gaseous communication 10 between the path 5 and the rest of 25 the containment vessel 2 avoids the generation of pressure differential loads on the path segments 8 and support segments 9.

First example of thermal processing

In one example, the first thermal processing apparatus 1 may be used for process 30 materials 3 in the form of calcium carbonate, CaCO₃, which is to be converted into calcium oxide, CaO, commonly referred to as “quicklime”.

The chemical process is:

CaCO₃ + Heat -+ CaO + C0₂

-14The calcium carbonate process materials 3 should be heated to a temperature within the range from 825 °C to 1200 °C. The processing should be conducted in a low oxygen environment, for example, by processing in an inert argon or nitrogen atmosphere or in vacuum. The carbon dioxide gas produced by the thermal processing may escape, or be 5 extracted from, the first thermal processing apparatus 1 via one or more gas outlets 20.

The wavelength band Δλ of the radiation 13 may be selected to correspond to, overlap with, or contain an absorbance of the calcium carbonate process materials 3, and a transmission window of the material used for the path segments 8.

For quicklime processing, the path segments 8 may be formed from materials such as, for example, aluminium oxynitride (A10N), aluminium nitride (A1N), magnesium aluminate spinel (MgAl₂O₄), quartz (crystalline Si0₂), fused silica (glassy Si0₂), alumina (A1₂O₃), sapphire (C1-AI2O3), or other materials suitable for use at processing temperatures within the range from 825 °C to 1200 °C.

The support segments 9 may be formed of conventional refractory brick materials or high temperature ceramics including borides, carbides, nitrides or oxides of early transition metals.

Second example of thermal processing

In a further example, the first thermal processing apparatus 1 may be used in the production of clinker and non-hydrated Portland cement from process materials 3 including tricalcium silicate (alite - Ca₃SiO₅), dicalcium silicate (belite - Ca₂SiO₄), tricalcium aluminate (Ca₃Al₂Oe), and tetracalcium aluminoferrite (Ca₂(Al,Fe)₂O₅).

The process materials 3 should be heated to temperatures of up to 1450 °C.

Advantageously, the radiation emitters 12 maybe configured to produce a temperature gradient, so that on a first portion of the path 5 the process materials 3 are heated to a calcining temperature of at least 600 °C, before heating to a fusion temperature of up to 30 1450 °C as the process materials 3 traverse a second portion of the path 5. The processing should be conducted in a controlled atmosphere such as an inert argon atmosphere or in vacuum. The wavelength band Δλ of the radiation 13 may be selected to correspond to, overlap with, or contain absorbance bands of the process materials 3 and a transmission window of the material used for the path segments 8.

-ι₅When the process materials 3 are a blend of materials, as in cement processing, it may be advantageous for a thermal processing apparatus 1 to include multiple types of radiation emitter 12 operating to generate radiation within multiple wavelength bands Δλ, each wavelength band Δλ tuned to a respective ingredient of the process materials

3·

For cement production, the path segments 8 maybe formed from materials such as, for example, aluminium oxynitride (A10N), aluminium nitride (A1N), magnesium aluminate spinel (MgAl₂O₄), quartz (crystalline Si0₂), fused silica (glassy Si0₂), alumina (A1₂O₃), sapphire (C1-AI2O3), or other materials suitable for use at processing temperatures of up to 1450 °C.

First example of jointing path segments in series in the axial direction

Referring also to Figures 5 and 6, a first longitudinal support segment 9a for jointing together path segments 8b in series along the axial direction 4 is shown.

The first support segment 9a includes an outer section 25 and an inner section 26 which both extend along the axial direction 4 when the first support segment 9a is installed. The inner and outer sections 25, 26 are connected by a bridging section 27 which extends between the inner and outer sections 25, 26 in a direction perpendicular 25 to the axial direction 4. The inner and outer sections 25, 26 have the same basic crosssectional shape as the path segments 8b which are to be jointed, but are respectively dimensioned so as to form between them a pair of slots 28 for receiving path segments 8b on either side of the bridging section 27.

In order to extend the path 5 in the axial direction 4, a first support segment 9a is fitted over a path segment 8b so that the path segment 8b is received into the slot 28 on one side of the first support segment 9a until the path segment 8b abuts the bridging section 27. Subsequently, a further path segment 8b is inserted into the other slot 28 of the first support segment 9a until the further path segment 8b abuts the bridging section 27. Alternatively, in some examples the path segments 8b may not abut the bridging section 27 in order to permit thermal expansion.

-16In this way, the path 5 may be readily extended in a modular fashion using the path segments 8b and first support segments 9a. This may be advantageous because ceramic materials cannot in practice be used to form path segments 8b of arbitrary 5 length. However, by jointing path segments 8b using support segments 9a, the length of the path 5 may be extended arbitrarily. Additionally, a modular construction of the path 5 may enable less complex and less expensive maintenance and repair of the path 5 should one or more path segments 8b or support segments 9a become damaged or degraded.

Although not shown in Figure 5 for simplicity, some or all of the first support segments 9a may also include or be attached to protrusions 22 (Figure 2) for supporting and/or suspending the path 5 at a distance from the interior walls of the containment vessel 2. Preferably, the length of path 5 spanning between adjacent first support segments 9a 15 having protrusions 22 (Figure 2) should not become excessively long, in order to avoid excessive mechanical loading of the path segments 8b and support segments 9a.

In some examples, the jointed path segments 8b maybe secured within the slots 28 using cement, adhesive, solder or other bonding methods suitable for the materials of 20 the path segments 8b and first support segment 9a. The cement, adhesive or other bonding material may be sufficiently compliant to allow for small displacements resulting from thermal expansion or contraction of the path segments 8b and support segments 9a.

The example shown in Figure 5 illustrates a first support segment 9a for joining tubular, square-sectioned path segments 8b in series in the axial direction 4. However, the first support segment 9a may have different cross-sectional shapes in order to be equally applicable to any shape of path segments 8 such as, for example, circular, triangular, pentagonal, or any other regular or irregular polygonal cross-sections.

The example shown in Figure 5 illustrates a first support segment 9a for joining tubular, square-sectioned path segments 8b which are integrally formed as a single piece. However, the first support segment 9a may be equally applicable to jointing path segments 8 (of any cross-sectional shape) which are formed from plate-like path segments 23 bonded together along the edges or jointed along the edges using edge support segments 24 (Figure 11).

-VSecond example of jointing path segments in series in the axial direction

Referring also to Figures 7 and 8, a second longitudinal support segment 9b for jointing together path segments 8b in series along the axial direction 4 is shown.

The second support segment 9b includes a collar section 29 shaped and dimensioned so that an inner surface 30 of the collar section 29 may receive a path segment 8, for example a square-sectioned path segment 8b. A limiting protrusion 31 extends inwardly from the inner surface 30 in order to restrict the length of the path segment 10 8b which may be received. The extension of the limiting protrusion 31 from the inner surface 30 is preferably equal to the thickness of the path segment 8 walls, so that an interior surface of the path 5 maybe substantially smooth.

In order to extend the path 5 in the axial direction 4, the collar section 29 of a second 15 support segment 9b is fitted over a path segment 8b until the path segment 8b abuts the limiting protrusion 31. Subsequently, a further path segment 8b is inserted into collar section 29 of the second support segment 9b until the further path segment 8b abuts the limiting protrusion 31.

The effects and advantages of the second support segment 9b are substantially the same as for the first support segment 9a.

Although not shown in Figure 7 for simplicity, some or all of the second support segments 9b may also include or be attached to protrusions 22 (Figure 2) for supporting and/or suspending the path 5 at a distance from the interior walls of the containment vessel 2. Preferably, the length of path 5 spanning between adjacent second support segments 9b having protrusions 22 (Figure 2) should not become excessively long, in order to avoid excessive mechanical loading of the path segments 8b and second support segments 9b.

In some examples, the jointed path segments 8b maybe secured within the collar section 29 using cement, adhesive, solder or other bonding methods suitable for the materials of the path segments 8b and second support segments 9b. The cement, adhesive or other bonding material may be relatively compliant in order to allow for displacements resulting from thermal expansion or contraction of the path segments 8b and support segments 9b.

-18The example shown in Figure 7 relates to a second support segment 9b for joining tubular, square-sectioned path segments 8b in series in the axial direction 4. However, the second support segment 9b may have different cross-sectional shapes in order to be 5 equally applicable to any shape of path segments 8 such as, for example, circular, triangular, pentagonal, or any other regular or irregular polygonal cross-sections.

The example shown in Figure 7 relates to a second support segment 9b for joining tubular, square-sectioned path segments 8b which are integrally formed as a single 10 piece. However, the second support segment 9b may be equally applicable to jointing path segments 8 (of any cross-sectional shape) which are formed from plate-like path segments 23 bonded together along the edges or jointed along the edges using edge support segments 24 (Figure 11).

Third example of jointing path segments in series in the axial direction

Referring also to Figures 9 and 10, a third longitudinal support segment 9c for jointing together path segments 8b in series along the axial direction 4 is shown.

The third support segment 9c is the same as the second support segment 9b, except that the third support segment 9c does not include the limiting protrusion 31.

In order to extend the path 5 in the axial direction 4, the collar section 29 of a third support segment 9c is fitted over a portion of a path segment 8b. Subsequently, a further path segment 8b is inserted into collar section 29 of the third support segment 25 9c until the two path segments 8b abuts one another.

The effects and advantages of the third support segment 9c are substantially the same as for the first and second support segments 9a, 9b.

Although not shown in Figure 9 for simplicity, some or all of the third support segments 9c may also include or be attached to protrusions 22 (Figure 2) for supporting and/or suspending the path 5 at a distance from the interior walls of the containment vessel 2. Preferably, the length of path 5 spanning between adjacent third support segments 9c having protrusions 22 (Figure 2) should not become excessively long, in order to avoid excessive mechanical loading of the path segments 8b and support segments 9c.

-19In some examples, the jointed path segments 8b maybe secured within the collar section 29 using cement, adhesive, solder or other bonding methods suitable for the materials of the path segments 8b and third support segments 9c. The cement, adhesive or other bonding material may be relatively compliant in order to allow for displacements resulting from thermal expansion or contraction of the path segments 8b and support segments 9c.

The example shown in Figure 9 relates to a third support segment 9c for joining tubular, square-sectioned path segments 8b in series along the axial direction 4.

However, the third support segment 9c may have different cross-sectional shapes in order to be equally applicable to any shape of path segments 8 such as, for example, circular, triangular, pentagonal, or any other regular or irregular polygonal crosssections.

The example shown in Figure 9 relates to a third support segment 9c for joining tubular, square-sectioned path segments 8b which are integrally formed as a single piece. However, the third support segment 9c may be equally applicable to jointing path segments 8 (of any cross-sectional shape) which are formed from plate-like path 20 segments 23 bonded together along the edges or jointed along the edges using edge support segments 24 (Figure 11).

First example of jointing edges parallel to the axial direction

Referring also to Figure 11, a square-sectioned path segment 8d formed by jointing 25 plate-like path segments 23 is shown.

The square-sectioned path segment 8d is formed by four plate-like path segments 23 arranged to form a square cross-section when viewed along the axial direction 4, with the edges running parallel to the axial direction 4 jointed using four edge support 30 segments 24. Each of the edge support segments 24 comprises a first slot 32a and a second slot 32b oriented at a 90 degree angle to the first slot 32a. The slots 32a, 32b extend in the axial direction 4.

In some examples, some or all surfaces 33 of one or more edge support segments 24b 35 which will define an interior surface of the path 5 when assembled may be bevelled,

- 20 curved or otherwise shaped so as to minimize discontinuities in the interior surface of the path 5 (see Figure 15).

The plate-like path segments 23 may be secured in the slots 32a, 32b using cement, adhesive, solder, or other suitable methods for bonding the materials of the plate-like path segments 23 and the edge support segments 24. The cement, adhesive or other bonding material may have sufficient compliance to accommodate displacements resulting from thermal expansion or contraction of the plate-like path segments 23 and the edge support segments 24.

Although not shown in Figure 11, some or all of the edge support segments 24 may include or be attached to protrusions 22 (Figure 2) for supporting or suspending the path 5 at a distance from the interior walls of the containment vessel 2.

Multiple square-sectioned path segments 8d assembled from plate-like path segments 23 and edge support segments 24 may be jointed together in series in the axial direction 4 using longitudinal support segments 9a, 9b, 9c as described hereinbefore.

The one or more radiation emitters 12 may be arranged to direct radiation 13 to intersect the path 5 substantially parallel to respective normals of one or more of the plate-like path segments 23. For example, a separate radiation emitter 12 maybe directed along the normal to each plate-like path segment 23 forming a squaresectioned path segment 8d, so that radiation 13 intersects the path 5 from above, below and either side of the path 5 (with respect to gravity when the first thermal processing apparatus 1 is installed and in use).

Second example of jointing edges parallel to the axial direction

Path segments 8 assembled from plate-like path segments 23 and edge support segments 24 are not restricted to square cross-sections, and in general path segments 8 30 assembled from plate-like path segments 23 and edge support segments 24 may have triangular, square, pentagonal, hexagonal, or any other regular or irregular polygonal shape.

For example, referring also to Figure 12, a second example of jointing plate-like path segments 23 along edges parallel to the axial direction 4 is shown.

- 21 An octagonal-sectioned path segment 8e is substantially the same as the squaresectioned path segment 8d, except that each path segment 8e includes eight plate-like path segments 23 arranged to form an octagon. Each of the edge support segments 24 comprises a first slot 32a and a second slot 32b oriented at a 135 degree angle to the first slot 32a. The slots 32a, 32b extend in the direction of the axis 4.

In some examples, some or all surfaces 33 of one or more edge support segments 24b which will define an interior surface of the path 5 when assembled may be bevelled, curved or otherwise shaped so as to minimize discontinuities in the interior surfaces 10 defining the path 5.

The plate-like path segments 23 may be secured in the slots 32a, 32b using cement, adhesive, solder, or other suitable methods for bonding the materials of the plate-like path segments 23 and the edge support segments 24. The cement, adhesive or other 15 bonding material may have sufficient compliance to accommodate displacements resulting from thermal expansion or contraction of the plate-like path segments 23 and the edge support segments 24.

Although not shown in Figure 11, some or all of the edge support segments 24 may 20 include or be attached to protrusions 22 (Figure 2) for supporting or suspending the path 5 at a distance from the interior walls of the containment vessel 2.

Multiple octagonal-sectioned path segments 8e assembled from plate-like path segments 23 and edge support segments 24 may be jointed together in series in the axial direction 4 using longitudinal support segments 9a, 9b, 9c as described hereinbefore.

The one or more radiation emitters 12 may be arranged to direct radiation 13 to intersect the path 5 substantially parallel to respective normals of one or more of the 30 plate-like path segments 23. For example, a separate radiation emitter 12 may be directed along the normal to each plate-like path segment 23 forming an octagonalsectioned path segment 8e.

Partially enclosed path

Referring also to Figure 13, an example of a partially enclosed path 5 is shown.

- 22 A partially enclosed path segment 8f may be assembled from three plate-like path segments 23 providing a floor and a pair of side-walls defining a trough or trench within which the processed material 3 may be contained during processing. An upper region of the path 5 is left exposed, and process materials 3 within the partially enclosed path segment 8f may receive radiation 13 without any attenuation from intervening path segments 8, 23. This is possible in the present specification because, unlike a rotary kiln, the first thermal processing apparatus 1 does not rotate. The upper region of the path 5 may be defined with respect to gravity when the thermal processing apparatus is installed and in service. A partially enclosed path segment 8f may not be used when the path 5 is oriented substantially vertically.

The plate-like path segment 23 providing the floor of the path 5 is jointed to the platelike path segments 23 providing the side walls by edge support segments 24 including a pair of slots 32a, 32b oriented at 90 degrees to one another. Optionally, the plate-like path segments 23 providing the side walls may be topped with respective capping edge support segments 34 having a single slot 35 each to receive a plate-like path segment 23·

The plate-like path segments 23 may be secured in the slots 32a, 32b, 35 using cement, 20 adhesive, solder, or other suitable methods for bonding the materials of the plate-like path segments 23 and the edge support segments 24, 34. The cement, adhesive or other bonding material may have sufficient compliance to accommodate displacements resulting from thermal expansion or contraction of the plate-like path segments 23 and the edge support segments 24, 34.

Although not shown in Figure 13, some or all of the edge support segments 24 may include or be attached to protrusions 22 (Figure 2) for supporting or suspending the path 5 at a distance from the interior walls of the containment vessel. Some or all of the capping edge support segments 34 may also include or be attached to protrusions 22 (Figure 2) connected to the interior walls of the containment vessel 2 in order to provide additional mechanical support to the plate-like path segments 23 providing the side walls.

Multiple open-topped path segments 8f assembled from plate-like path segments 23 and edge support segments 24 may be jointed together in series in the axial direction 4 using support segments 9, 9a, 9b, 9c as described hereinbefore. Additionally, multiple

-23open-topped path segments 8f may be jointed in series in the axial direction along with multiple square-sectioned path segments 8d, so as to provide a path 5 in which an upper region of the path 5 is not enclosed along at least a portion of the length of the path 5.

The one or more radiation emitters 12 may be arranged to direct radiation 13 to intersect the path 5 substantially parallel to respective normals of one or more of the plate-like path segments 23. For example, a separate radiation emitter 12 maybe directed along the normal to each plate-like path segment 23 forming an open-topped 10 path segments 8f, as well as the normal to the omitted plate-like path segment 23, so that radiation 13 intersects the path 5 from above, below and either side of the path 5.

Although the partially enclosed path segment 8f has been shown in Figure 13 as having a square cross section in which one side has been removed, this need not be the case.

In general, partially enclosed path segments 8f may be produced having triangular, pentagonal, hexagonal, or any other regular or irregular polygonal shape, by omitting one or more sides.

Example of a path defined without jointing in series along the axial direction

In examples described so far, path segments 8 have been jointed in series in the axial direction 4 using longitudinal support segments 9a, 9b, 9c. However, in other examples, a path 5 maybe defined using only plate-like path segments 23 and edge support segments 24, 24b.

Referring also to Figures 14 and 15, an example of assembling a square-sectioned path 5 using plate-like path segments 23 and edge support segments 24b is shown.

Plate-like path segments 23 maybe inserted into the slots 32a, 32b of the edge support segments 24b so as to abut the adjacent plate-like path segments 23 in the axial direction 4. The joints between adjacent edge support segments 24b in the axial direction 4 are spanned by plate-like path segments 23. The plate-like path segments 23 and edge support segments 24b maybe bonded using cement, adhesive, solder or any other bonding method suitable for the materials of the plate-like path segments 23 and edge support segments 24b. Additionally, adjacent plate-like path segments 23 may be bonded to one another using cement, adhesive, solder or any other bonding methods suitable for the material of the plate-like path segments 23. This may be

-24unnecessary if a residual gap between adjacent plate-like path segments 23 can be made smaller than the typical particle/granule/pellet size of the process materials 3. Adjacent edge support segments 24b may also be bonded to one another using cement, adhesive, solder or any other bonding methods suitable for the material of the edge 5 support segments 24b. The cement, adhesive or other bonding material may have sufficient mechanical compliance to accommodate displacements resulting from thermal expansion or contraction of the plate-like path segments 23 and edge support segments.

In this way, a path 5 may be assembled in a modular way, whilst avoiding or minimising discontinuities in the axial direction 4, which is also the flow direction for the process materials 3.

Although not shown in Figures 14 or 15, some or all of the edge support segments 24b 15 may include or be attached to protrusions 22 (Figure 2) for supporting or suspending the path 5 at a distance from the interior walls of the containment vessel 2.

Second thermal processing apparatus

Referring also to Figure 16, a second thermal processing apparatus ib is shown.

The second thermal processing apparatus ib is the same as the first thermal processing apparatus 1, except that the second thermal processing apparatus ib further includes a helical screw 17 comprising a cylindrical core 36 and fins 37. The helical screw 17 is enclosed within the path 5 and is configured to assist in moving the process materials 3 25 along the path 5. The helical screw 17 may act to mix the process materials 3 to encourage uniform heating, and may also help to avoid stagnant regions of process materials 3 from developing. The materials used for the helical screw 17 may depend on the intended operating temperatures. For example, for a low temperature process the helical screw 17 may be formed of carbon steel. However, for a high temperature 30 process, the helical screw 17 may be formed of high temperature steels such as, for example, secondary hardened steels comprising tungsten, molybdenum and/or vanadium. In some examples, the helical screw 17 may be formed from, or coated with, tungsten carbide or titanium carbide. Use of tungsten carbide or titanium carbide may be particularly useful for resisting abrasion of the helical screw 17 by the process materials 3.

-25The helical screw 17 may also function as an additional heater for the process materials

3. The helical screw 17 may be heated using, for example, resistance (Joule) heating, inductive heating, or any other suitable heating mechanism.

Although not shown in Figure 16, the axial direction 4 of the second thermal processing apparatus ib is preferably oriented at an angle Θ to the horizontal when installed and in service. However, in some examples the inclusion of the helical screw 17 may avoid the need for the second thermal processing apparatus ib to be oriented at an angle Θ to the horizontal, so that the path 5 maybe substantially horizontal with respect to gravity when installed and in use.

Although the radiation emitters 12 have been shown below the path 5 in Figure 16, radiation emitters 12 may be directed at the path 5 from any angle in the same way as the first thermal processing apparatus 1.

Third thermal processing apparatus

Referring also to Figure 17 a third thermal processing apparatus ic is shown.

The third thermal processing apparatus ic is the same as the first thermal processing apparatus 1, except that the third thermal processing apparatus ic further includes one or more additional material inlets 38 configured to introduce additional process materials 3 at one or more intermediate positions along the path 5 between the first and second ends 6, 7.

Although not shown in Figure 17, the axis 4 of the third thermal processing apparatus ic is preferably oriented at an angle θ to the horizontal when installed and in service. Although the radiation emitters 12 have been shown below the path 5 in Figure 17, radiation emitters 12 may be directed at the path 5 from any angle in the same way as the first thermal processing apparatus 1.

Optionally, the third thermal processing apparatus ic may further include the helical screw 17 to provide additional mixing, and optionally heating, of the process materials 3·

Fourth thermal processing apparatus

Referring also to Figure 18 a fourth thermal processing apparatus id is shown.

- 26 The fourth thermal processing apparatus id is the same as the first thermal processing apparatus 1, except that the fourth thermal processing apparatus id further includes one or more vibrational exciters 39 attached to one or more support segments. The 5 vibrational exciters 39 may be attached to the main part of a support segment 9, or to one or more protrusions 22 (Figure 2) thereof. Additionally or alternatively, one or more vibrational exciters 39 may be attached to one or more path segments 8. The vibrational exciters 39 are configured to vibrate the path 5 in order to prevent or reduce adhesion of process materials 3 to the path 5. The vibrational exciters 39 may also help 10 to reduce or prevent the development of stagnant regions of process materials 3 within the path 5. Vibrational exciters 39 may be piezoelectric actuators, unbalanced rotating masses, or any other suitable vibration exciting means.

Although not shown in Figure 18, the axis 4 of the fourth thermal processing apparatus 15 id is preferably oriented at an angle Θ to the horizontal when installed and in service.

Although the radiation emitters 12 have been shown above the path 5 in Figure 18, radiation emitters 12 may be directed at the path 5 from any angle in the same way as the first thermal processing apparatus 1.

Optionally, the fourth thermal processing apparatus id may also include the helical screw 17 to provide additional mixing, and optionally heating, of the process materials 3. Additionally or alternatively, the fourth thermal processing apparatus id may also include one or more additional material inlets 38 configured to introduce additional process materials 3 at one or more intermediate positions along the path 5 between the 25 first and second ends 6, 7.

Modifications

It will be appreciated that many modifications may be made to the embodiments hereinbefore described. Such modifications may involve equivalent and other features 30 which are already known in the design, manufacture and use of thermal processing apparatus, and which may be used instead of or in addition to features already described herein. Features of one embodiment may be replaced or supplemented by features of another embodiment. Optional, preferable or non-essential features of embodiments may be omitted.

-27Typically the containment vessel 2 is cylindrical, but this need not be the case when pressure differentials for processing are relatively low.

Although the example shown in Figures 14 and 15 is for assembling a square sectioned 5 path segment 8d, the described assembly method is equally applicable to assembling path segments 8 having triangular, pentagonal, hexagonal, or any other regular or irregular polygonal shape.

Although the plate-like path segments 23 and edge support segments 24b shown in 10 Figures 14 and 15 have substantially equal lengths in the axial direction 4, this need not be the case. For example, the edge support segments 24b may be substantially longer in the axial direction 4 than the plate-like path segments 23, such that each edge support segment 24b receives multiple plate-like path segments 23 along the axial direction 4.

Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or 20 not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claims

1. Thermal processing apparatus, comprising:

a containment vessel for providing a controlled atmosphere or a vacuum, the

5 containment vessel elongated in a first direction and containing:

a path for process materials, the path being elongated in the first direction and defined by a plurality of path segments which are jointed to one another by a plurality of support segments, wherein the path is in gaseous communication with the rest of the containment vessel;

io one or more radiation emitters configured to heat process materials within at least a portion of the path using radiation within a bandwidth; wherein the path segments comprise a first material which transmits radiation within the bandwidth.

15

2. Thermal processing apparatus according to claim i, wherein at least some of the support segments are connected to the containment vessel so as to suspend the path at a distance from the sides of the containment vessel.

3. Thermal processing apparatus according to any preceding claim, wherein the 20 path has a non-circular cross-section.

4. Thermal processing apparatus according to any preceding claim, wherein the one or more radiation emitters comprise microwave emitters.

25 5. Thermal processing apparatus according to any preceding claim, wherein the one or more radiation emitters are configured to heat process materials within at least a portion of the path according to a predetermined or dynamically programmable profile.

6. Thermal processing apparatus according to any preceding claim, wherein the

30 path segments comprise one or more flat plates or sheets of the first material.

7. Thermal processing apparatus according to any preceding claim, wherein an upper region of the path is not enclosed along at least a portion of the length of the path.

8. Thermal processing apparatus according to any preceding claim, further comprising a helical screw enclosed within the path and configured to assist in moving process materials along the path.

5 9. Thermal processing apparatus according to claim 7, wherein the helical screw is heated.

10. Thermal processing apparatus according to any preceding claim, wherein the first material is a refractory material.

11. Thermal processing apparatus according to any preceding claim, wherein the first material is aluminium oxynitride.

12. Thermal processing apparatus according to any preceding claim, wherein the

15 support segments are formed of a second material, wherein the second material is a refractory material.

13. Thermal processing apparatus according to any preceding claim, wherein the support segments are formed by 3D printing.

14. Thermal processing apparatus according to any preceding claim, further comprising one or more additional material inlets configured to introduce additional process materials at one or more intermediate positions along the path.

25

15. Thermal processing apparatus according to any preceding claim, further comprising one or more vibrational exciters attached to one or more path segments and/or one or more support segments.

16. A method comprising:

30 introducing process materials into a first end of a path for process materials, the path being elongated in a first direction and defined by a plurality of path segments which are jointed to one another by a plurality of support segments, wherein the path is enclosed within a containment vessel for providing a controlled atmosphere or a vacuum, and wherein the path is in gaseous communication with the rest of the

35 containment vessel;

-30heating processed materials within at least a portion of the path using radiation within a bandwidth, wherein the path segments comprise a first material which transmits radiation within the bandwidth;

extracting process materials from a second end of the path.

17. The method may comprise one or more of calcination of process materials, thermal desorption of one or more volatile substances present in the process materials, sintering the process materials, agglomerating the process materials, reduction roasting of the process materials, drying the process materials and or pelletizing the process

10 materials.

18. The method may be carried out using the thermal processing apparatus according to any one of claims 1 to 15.