WO2024173994A1

WO2024173994A1 - Processing apparatus

Info

Publication number: WO2024173994A1
Application number: PCT/AU2024/050138
Authority: WO
Inventors: Nicholas Glen Bernard; John Maxwell BULTITUDE-PAULL; Mostafa SHARAFELDEEN; Philip Scott Heckley; Daniel Thomas MCGRATH; Suresh SAKAR
Original assignee: Iluka Resources Ltd
Current assignee: Iluka Resources Ltd
Priority date: 2023-02-24
Filing date: 2024-02-23
Publication date: 2024-08-29
Anticipated expiration: 2025-08-24

Abstract

A processing apparatus (10) includes one or more vessels (20) for containing respective contents and a heating device (12). The heating device (12) has predefined zones (14, 16, 18) to heat and cool the contents of the one or more vessels (20) according to a heating regime. The predefined zones include a preheat zone (14) operable to heat the contents at an average rate within the range of about 2°C per minute to about 7°C per minute until reaching a holding temperature within the range of about 270°C to about 1000°C. The predefined zones include a holding zone (16) to hold the contents at the holding temperature. The holding temperature is the peak temperature of the heating regime. A moving device (21) moves the vessels (20) sequentially through the zones. A mixer or mixing station (34) may be provided upstream of the heating chamber (24) to premix the contents before heating. A recycler (32) may be provided for converting at least a portion of gas from the gas flow through the chamber to an acid in liquid form, wherein the recycler (32) is fluidly connected to discharge the liquid acid to the mixer or mixing station (34).

Description

Processing Apparatus

Field of the invention

[0001] The present invention relates to a processing apparatus for processing a material according to a heating regime, for example a tunnel kiln. The processing apparatus may have specific application to the process described in Australian patent application 2023900482 filed on 24 February 2023 or related PCT application filed on 23 February 2024 and may specifically relate to an apparatus for refining a mineral sand particulate. However, the inventions described herein are not limited to that application and other applications are possible.

Cross Reference

[0002] The present application is related to co-pending application 2023900482 filed in our name on 24 February 2023. References to a “specific application” of the present dimension are detailed further in the co-pending application. However, the application of the present invention is not limited to the specific application.

[0003] The present application claims priority to Australian patent application 2023900481 filed on 24 February 2023, the entire contents of which are incorporated herein by reference.

Background of the invention

[0004] Reaction processes, for refining of minerals for example, may generate highly corrosive materials or precursors to highly corrosive materials, for example sulphur trioxide in gaseous form, which, when coming into contact with water forms sulphuric acid.

[0005] Due to the corrosive nature, it will be appreciated that the handling of sulphur trioxide and sulphuric acid poses certain difficulties for human safety and the lifespan of plant and equipment. Accordingly, the present invention aims to provide apparatus for more effectively dealing with corrosive materials in reaction processes.

[0006] An alternative object of the invention is to provide the public with a useful choice over known apparatus for reaction processing. [0007] Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.

Summary of the invention

1. processing apparatus with predefined zones operating within specified temperature ranges

[0008] In accordance with an aspect of the present invention, there is provided, a processing apparatus, the apparatus including: one or more vessels for containing respective contents; a heating device having predefined zones to heat and cool the contents of the one or more vessels according to a heating regime, the predefined zones including:

A) a preheat zone operable to heat the contents at an average rate within the range of about 2 °C per minute to about 7°C per minute until reaching a holding temperature within the range of about 270°C to about 1000°C; and

B) a holding zone to hold the contents at the holding temperature, wherein the holding temperature is the peak temperature of the heating regime; a moving device to move the vessels sequentially through the zones A and B.

[0009] Preferably, the preheat zone may heat the contents at an average rate in the range of about 2 - 5°C/min, such as about 2°C/min, about 2.5°C/min, most preferably about 3°C/min, about 3.5°C/min, about 4°C/min, about 4.5°C/min or about 5°C/min. The heating profile (T vs t) may be linear but need not be linear. The starting (initial) temperature of the contents of the vessel in the preheat zone may be ambient temperature. However, if the contents are mixed ingredients which react at ambient temperature, then the temperature of the contents may be higher than ambient temperature. The heating device may operate to provide conditions which are at a higher temperature than the temperature of the contents. For example, the operating temperature of the heating device for the holding zone may be 100°C to 150°C above the holding temperature. This applies to any of the holding temperatures specified in this specification. For example, if the holding temperature is about 1000°C then the operating temperature of the heating device may be in the range of about 1100°C to about 1250°C.

[0010] The start of the preheat zone i.e. where the vessels initiate their movement in the preheat zone is preferably above the dew point of sulphuric acid (depends on the concentration of sulfur trioxide in the gas, but is typically about 138°C), but not more than about 250°C.

[0011] Preferably the holding zone may hold the contents above about: 270°C i.e. within the range of about 270°C to 1000°C; 500°C, for example within the range of about 500°C to 1000°C; 840°C, for example, within the range of about 840°C to 1000°C; or 884°C, for example within the range of about 884°C to 1000°C. More preferably, the holding zone may hold the contents within the range of about 900°C to 1000°C.

[0012] In a preferred form of the invention, the preheat zone and the holding zone may be provided within a singular heating device. The heating device may be programmed to provide the heating regime. Preferably, the singular heating device is in the form of an elongate oven, tunnel furnace, roller furnace or tunnel kiln.

[0013] In some embodiments, the minimum time the contents are heated from an initial temperature to the peak (holding) temperature is at least about 2 hours (h), 3h, 4h, 5h or 6h. The maximum time the contents are heated from an initial temperature to the peak temperature may be not more than about 9h, 8h, 7h, 6h, 5.5h, 5h, 4h, or 3h. The time the contents are heated from an initial temperature to the peak temperature may be from any of these minimum times to any maximum time provided the minimum time is shorter than the maximum time. For example, the time the contents are heated from an initial temperature to the peak temperature may be from about 2h to about 9h or from about 5h to about 7h. Any of the heating profiles (eg average rates) described herein may be used across these times.

[0014] Residence time in the holding zone may be about 1 to 3 hours, most preferably about 2 hours. In some embodiments, the time the peak (holding) temperature is maintained may be at least about 0.5h, 1 h or 2h. The maximum time the peak temperature is maintained may be not more than about 5h, 4h, 3h or 2h. The time the peak temperature is maintained may be from any of these minimum times to any of these maximum times provided the minimum is shorter than the maximum. For example, the time the peak temperature is maintained may be from about 0.5h to about 5h or from about 1h to about 3h.

[0015] The heating device may be operable such that the overall residence time of A+ B is in the range of about 5 to 7 hours.. The residence time in the holding zone is preferably shorter than the residence time in the preheat zone.

[0016] The predefined zones may also include a cooling zone or cooling station (C) for cooling the contents. Preferably the cooling zone or cooling station is operable to maintain the contents at a temperature below the holding temperature. The cooling zone (C) may be incorporated into the heating chamber/device. Alternatively, the cooling station (C) may be downstream of the heating chamber/device. The moving device may move the vessels sequentially through the zones A, B and C. In a preferred form of the invention, the preheat zone and the holding zone and the cooling zone may be provided within the singular heating device.

[0017] The contents may be passively cooled, for example by removing a source of heat. In other embodiments, the contents may be actively cooled. The contents may be cooled to a temperature of not more than about 70°C, 60°C, 50°C, 40°C, 30°C, 25°C or 20°C.

[0018] The apparatus/heating device may be operable such that the overall residence time of A+ B + C is in the range of about 7 to about 24 hours, about 7 to about 20 hours, about 7 to about 15 hours, about 7 to about 13 hours, about 7 to 9 hours, or more preferably, about 8 to 9 hours.

[0019] The moving device may be in the form of a conveyor with the vessels provided on the conveyor. For example, the roller furnace may have driven rollers to convey the vessels through the apparatus. Alternatively cars or carriages may be provided to carry either individual vessels or a plurality of vessels. [0020] The one or more vessels may be moved through the singular heating device at a constant speed, with the length of each zone dictating the residence time within each zone. Alternatively, the one or more vessels may be moved through the singular heating device at variable speeds according to the required residence time in each zone. The provision of cars or carriages can be readily adapted to variable speeds. Moving the vessels at variable speeds may reduce the required length for the elongate oven, tunnel furnace or tunnel kiln.

[0021] Any of the features described in the aspects below may have application to this aspect.

2. Processing apparatus operable according to a heating regime

[0022] In accordance with another aspect of the present invention, there is provided, a processing apparatus including: one or more vessels for containing respective contents; one or more heating device operable to heat the contents of the one or more vessels according to a heating regime comprising:

A) heating the contents at an average rate within the range of about 2°C per minute to about 7°C per minute until reaching a holding temperature in the range of about 270°C to about 1000°C; and

B) holding the contents at the holding temperature, wherein the holding temperature is the peak temperature of the heating regime.

[0023] Preferably, the heating device is operable to heat the contents at an average rate of 2 - 5°C/min, most preferably 3°C/min. The heating profile (T vs t) may be linear but need not be linear. The starting temperature of the contents of the vessel may be ambient temperature. However, if the contents are mixed ingredients which react at ambient temperature, then the temperature of the contents may be higher than ambient temperature. The heating device may operate to provide conditions which are at a higher temperature than the temperature of the contents. The starting temperature of the heating device is preferably not more than about 250°C. The heating device is preferably programmed to provide the heating regime. [0024] Preferably the heating device is operable to hold the contents above about: 270°C i.e. in the range of about 270°C to 1000°C; 500°C, for example within the range of about 500°C to 1000°C; 840°C, for example, within the range of about 840°C to 1000°C; or 884°C, for example within the range of about 884°C to 1000°C. Preferably the apparatus is operable to hold the contents within the range of about 900°C to 1000°C

[0025] The heating device may be operable such that the overall time of A+ B is in the range of about 5 to about 15 hours, about 5 to about 10 hours, about 5 to about 8 hours, or about 5 to about 7hours. The approximate duration at the holding temperature may be 1 to 3 hours, most preferably about 2 hours.

[0026] The heating regime may include cooling. The apparatus/heating device may be operable such that the overall duration of A+ B+ C is in the range of about 7 to about 24 hours, about 7 to 9 hours, or more preferably, about 8 to 9 hours.

[0027] A heating chamber may be provided, such as a furnace, either electric or gas fired.

[0028] The heating device may comprise an elongate heating device, with the one or more vessels being movable along the elongate heating device, for example, the one or more vessels may be moved through a tunnel furnace, roller furnace or tunnel kiln. The elongate heating device may have various different zones including a heating zone, a holding zone and a cooling zone. The heating device may be made up of modular units as is known in the art.

[0029] The one or more vessels may be conveyed through the heating device one after the other in a first direction. The apparatus may be operable to induce gas flow through the chamber in a second direction which is opposite to the first direction.

[0030] Any of the features described in accordance with other aspects above or below may have application to this aspect of the invention.

3. Counter current gas flow + recycler

[0031] In accordance with another aspect of the present invention, there is provided, a processing apparatus including: one or more vessels for containing respective contents; a heating chamber operable to heat the contents of the one or more vessels according to a heating regime, wherein the apparatus is operable to move the one or more vessels through the heating chamber in a first direction and induce gas flow through the chamber in a second direction which is opposite to the first direction; a mixer or mixing station, upstream of the heating chamber to premix the contents before heating; and a recycler for converting at least a portion of gas from the chamber to an acid in liquid form wherein the recycler is fluidically connected to discharge the liquid acid to the mixer or mixing station.

This aspect also relates to an apparatus for moderating corrosive materials in a reaction process within the heating chamber. For instance, a control system may be provided to ensure that the temperature within the heating chamber is maintained above the dew point of the relevant acid. Alternatively, or additionally, the control system may moderate the gas flow through the heating chamber to control the atmosphere within the heating chamber, particularly the concentration of a portion of the gas comprising acid in gaseous form.

Any of the features described in accordance with other aspects above or below may have application to this aspect of the invention.

4. Counter current gas flow + condenser

[0032] In accordance with yet another aspect of the present invention, there is provided, a processing apparatus including: one or more vessels for containing contents; a heating chamber operable to heat the contents of the one or more vessels according to a heating regime, wherein the apparatus is operable to move the one or more vessels through the heating chamber in a first direction and induce gas flow through the chamber in a second direction which is opposite to the first direction; a mixer or mixing station, upstream of the heating chamber to premix the contents before heating; and a condenser/cooler for creating condensate from at least a portion of gas from the chamber, wherein the condenser/cooler is fl uidically connected to discharge the condensate to the mixer.

[0033] Preferably the gas flow is induced by providing a gas/air entry port and a gas outlet port disposed to induce the gas flow in the second direction. The gas outlet port may be in gaseous or fluid communication with the recycler/condenser/cooler. Accordingly, gas may be withdrawn from the chamber through the gas outlet port to the recycler or condenser/cooler.

[0034] Preferably, the heating chamber is an elongate heating chamber with a variable temperature along the length of the heating chamber. Preferably, the heating chamber is comprised of one or more of zones for heating and optionally cooling and the one or more vessels pass sequentially through the zones. Accordingly, the heating chamber may be in the form of a tunnel furnace. These zones may include a preheat zone operable to heat the contents at an average rate in the range of about 2°C/min to about 7°C/min, preferably at an average rate of 2°C/min to 5°C/min and most preferably 3°C per minute; and a holding zone to hold the contents at a holding temperature of at least about 840°C or more preferably in the range of about 884°C to about 1000°C, most preferably about 900°C to about 1000°C, and most preferably about 950°C. A cooling zone may additionally be provided for cooling the contents. However, the contents may also cool outside the chamber. [0035] Preferably, the heating chamber includes an entry port for the entry of the one or more vessels or for the intended contents thereof. The gas exit port may be adjacent the entry port. The gas exit port may be disposed in the preheat zone, most preferably at the start of the preheat zone (relative to the direction of travel of the vessels).

[0036] In any intended application, the off gas and/or vapour exiting from the heating chamber through the gas exit port may include products of reactions and combustion taking place within the heating chamber. For example, these gas(es) may include nitrogen, carbon dioxide, water, and unused oxygen. These gas(es) may include compounds in gaseous form which may condense to produce corrosive substances or combine with water molecules or vapour to produce corrosive substance such as acid which could be detrimental to the chamber if condensate is produced within the chamber. Preferably, the apparatus is operable to maintain at least the preheat zone above the dew point of any such corrosive substance or acid since there may be water present as a result of a reaction within the chamber, and/or as a result of combustion. Therefore, the condensation of acid within the chamber is minimised or avoided. The removal of the acid from the heating chamber preferably occurs above the dew point of the acid.

[0037] In a specific application for refining a mineral sand particulate, the exiting gas(es) and/or vapour may include sulphur trioxide. Preferably the apparatus is operable to maintain at least the heating chamber or at least the preheat zone above the dew point of sulphuric acid since there may be water present as a result of a reaction within the chamber or as a result of combustion. Therefore, the condensation of sulphuric acid within the chamber is minimised or avoided. The removal of the sulphur trioxide from the heating chamber preferably occurs above the dew point.

[0038] The gas entry port may be intended for the entry/injection of air. The gas entry port may include an injector. The gas entry port may be disposed in the cooling zone, or in the absence of a cooling zone the gas entry port may be disposed at the end of the holding zone (relative to the first direction). Accordingly, during operation of the apparatus, airflow/gasflow is induced in the direction towards the pre-heat zone from the cooling zone, or in the absence of a cooling zone, from the holding zone. In the specific application, the advantage of airflow in the counter direction is that air used for cooling in the cooling zone is preheated air for the holding zone and optionally the heating zone, which is advantageous for natural gas combustion (for heating) occurring in the zone(s).

[0039] The mixer, upstream of the heating device to premix the contents before heating, may be disposed for example before entry into the heating chamber.

[0040] The recycler or the condenser/cooler is preferably operable to transform the sulphur trioxide into liquid form i.e. liquid sulphuric acid for reuse as one of the reactants in the specific application. Accordingly, the recycler may be fluidically connected to discharge liquid acid to the mixer. The recycler may operate to absorb SO3 into water.

[0041] The foregoing preferred features may have application to any of the other aspects of the invention.

Other preferred features

[0042] The following preferred features may have application to any of the aspects of the invention described above or below.

[0043] Preferably, the apparatus includes a plurality of vessels on a continuous path through the heating device/chamber. In other words, the processing of the reactants is batchwise, with each vessel passing separately through the heating device/chamber. The vessels may exit the heating device/chamber and then return empty to the start of the heating device/chamber. Alternatively, the vessels may remain in the heating chamber forming a return line to the entry port, or adjacent thereto. Such processing of vessels through the heating device/chamber in a continuous manner is referred to as “semi-continuous”.

[0044] As noted above, the heating device or heating chamber may not incorporate a cooling zone. If the contents of the vessels after being held at the holding temperature are liquid then it may be advantageous to remove the contents from the vessels in liquid form. Accordingly, the apparatus may include a liquid or molten discharge station which is downstream of the holding zone.

[0045] The vessels may exit the heating device/chamber to the discharge station. The discharge station may operate to tip the vessel to discharge the liquid or molten contents. The vessels may have a pouring lip for this purpose. [0046] Preferably, after discharge, the apparatus is operable to return at least some of the vessels to the heating device/chamber before cooling of the vessels reaches ambient temperature such that said vessels retain heat for processing the next batch. The apparatus may be operable to return the vessels before substantial cooling of the vessels. For instance, the vessels may be returned to the heating device/chamber within the range of about 250°C to about 840°C. Preferably, a return device, such as a conveyor is operable to make the return.

[0047] The or each vessel may be in the form of a crucible. The or each vessel may be comprised of a refractory material comprising silicon carbide or a vessel of another material which is completely or substantially lined or coated, at least internally, with a refractory material comprising silicon carbide. Potential refractory materials in this category include siliconised silicon carbide (SiSiC) and nitride bonded silicon carbide. The or each vessel may be adapted to contain an atmosphere comprising sulphur trioxide (eg any SO3 atmosphere described herein). Alternatively, the vessels may be comprised of metal.

[0048] The heating chamber may be in the form of a tunnel kiln where the vessels are moved on respective cars.

[0049] The heating device/chamber is preferably sized to accommodate the vessels. The chamber may be heatable to a temperature of at least about 270°C, preferably at least about 500°C, more preferably, at least about 840°C, or more preferably at least about 884°C (and most preferably about 950°C or about 1000°C). The heating chamber may be adapted to accommodate a pressure of gas, or reagent gas or sulphur trioxide of greater than 1 atm such that the vessel within is subject to the pressure of greater than 1 atm.

[0050] It will be understood that the heating device may operate to provide conditions which are at a higher temperature than the temperature of the contents. For example, the operating temperature of the heating device for the holding zone may be 100°C to 150°C above the holding temperature. This applies to any of the holding (peak) temperatures specified in this specification. For example, if the holding (peak) temperature is about 1000°C then the peak operating temperature of the heating device may be in the range of about 1100°C to about 1250°C. [0051] Preferably, the vessels are open to the atmosphere within the heating chamber.

[0052] The apparatus may include a mixer or mixing station, upstream of the heating device or heating chamber to premix the contents before heating, for example before entry into the heating chamber. The mixing may be by way of an auger, screw or ribbon.

[0053] The mixer may discharge into the vessels batchwise, such that each vessel receives the contents premixed. For this purpose, the mixer may include a mixing vessel or container having a pouring opening or spout, discharge opening, or dispenser. The pouring opening or spout, discharge opening, or dispenser may be adapted for the discharge of the mixed contents into the one or more vessels after mixing. Where the contents are in the form of a slurry or suspension, the pouring opening or spout, discharge opening, or dispenser may be specifically adapted for discharge of the slurry or suspension. In one form, the mixing vessel or container may be pivotable or tippable for pouring out the contents into the one or more vessels. The mixer preferably dispenses a metered amount of the mixed materials.

[0054] Alternatively, a mixer may mix the materials in the or each vessel, upstream of the heating device or in the preheat zone of the heating device.

[0055] Optionally, the mixing vessel or container is fluidly connected to the outlet of the recycler, for reuse of the recycled liquid in the process. The mixing vessel or container may also receive a feed of other materials to be mixed together.

[0056] Alternatively, the vessel and the chamber (or furnace) may be fluidical ly separated such that the heating chamber (or furnace) is not exposed to the corrosive environment within the vessel. The vessel may be a closed vessel within the chamber.

[0057] Heating is typically electric heating, usually electrical resistance elements, or indirect flame or fired, whereby the hot combustion gas would be on the outside of the containment vessel/reactor. The indirect heat source should have the capability for the vessel and/or the contents thereof to reach at least about 270°C, at least about 500°C, at least about 840°C, or more preferably 884°C and most preferably at least about 950°C, and/or any of the process temperatures mentioned elsewhere. [0058] Alternatively, the heating device or chamber may be direct fired. Where burners are used for burning combustible gas, the burners are preferably located in the sidewalls at a height which is above the height of the contents within the vessels. Mixed heat sources are also possible, for example electric and gas fired.

[0059] SO3 may be generated within the chamber as part of the reaction of the specific application. The apparatus may also be in fluid/gas communication with an SO3 and/or SO2 analyser. The vessel may be directly fluidly/gas phase connected with the analyser. Preferably, the reactant gas drawn to the analyser may be diluted prior to entry to the analyser. The analyser may be run intermittently or periodically or continuously to monitor the SO3 and/or SO2.

[0060] A control system may be provided to receive signals corresponding to SO3 and/or SO2 data from the analyser. The control system may also ensure maintenance of the desired partial pressure range of sulfur trioxide and/or a desired gaseous composition range of SO3 and other gases such as SO2 and 02. The control system may also control the operation of the analyser such as the frequency of sampling. The control system may also receive feedback of other parameters such as temperature and control the operation of the apparatus accordingly. For example, the control system may control the operation of the apparatus by coordinating the introduction and/or flow of the gas/air stream with the measured temperature of the vessel. The control system may also coordinate the exhaust of the gas(es) with the introduction of a less reactant gas and/or inert gas such as nitrogen. The control system may be programmed to operate the apparatus to carry out any features or processes set out in the remainder of the specification.

[0061] The apparatus (or reactor) used for this process may be corrosion resistant. Suitable corrosion resistant and/or refractory materials may include ceramics, for example, silicon carbide and fused quartz. The reactor may be constructed from any suitable corrosion resistant material, or more typically, surfaces of the reactor that may contact the corrosive reagents/intermediates are coated with one or more of these suitable materials. In some embodiments, the reactor surfaces that may contact the corrosive reagents/intermediates comprise a coating of refractory material comprised of silicon carbide, with various material variants being as discussed above. [0062] The preferred ceram ic/refractory material comprised of silicon carbide is siliconized SiC (SiSiC). Siliconized SiC also called silicon bonded SiC. It is a SiC to which Si metal powder is added during the ceramic shape forming stage. When the shape is fired (~1500°C), the Si metal melts and fills the pores of the SiC matrix giving a dense impermeable structure.

[0063] The heating chamber may be sealed to maintain the desired partial pressure or desired gaseous composition within the vessel. Alternatively, the apparatus may allow for intermittent, periodic or constant introduction of gas(es) e.g. air, into the vessel through the entry port(s), with the flow rate of introduction and removal of gas maintaining the desired partial pressure. In other words, the chamber is preferably physically closed, apart from the one or more ports which allow for introduction and removal of gas (and optionally other port(s) for the introduction of the vessels and/or the vessel contents such as mineral sand particulate, other reactants and removal of the product). To maintain the desired conditions within the chamber, airlocks may be provided for entry/exit of the vessels, with purge stations within the airlocks to control the conditions when the vessels enter/exit.

[0064] The heating, preferably electric, may be incorporated into the vessel itself, such as the wall or base of the vessel. For instance the vessels could be individually heated according to the heating regime. Alternatively, the cars carrying the vessels may incorporate the heating device.

[0065] Additionally, an air dryer may be provided to dry fresh air before injection into the apparatus.

5. Mixer - slurry or suspension into vessels

[0066] In accordance with yet another aspect of the present invention, there is provided, a processing apparatus including: a mixer for mixing feed materials to a slurry or suspension, the mixer including a pouring opening or spout, discharge opening, or dispenser for discharging the mixed contents of the mixer into a plurality of vessels such that each vessel receives a metered quantity of the mixed feed materials; a heating chamber having predefined heating or heated zones; the apparatus being operable to move the plurality of vessels through zones within the heating chamber such that the contents of the vessels are subjected to a heating regime according to the temperature and duration in each zone.

[0067] The feed materials are thus fully mixed before the homogeneous mix is charged into discrete vessels which are transported through the heating chamber. Each of the vessels are preferably open to the atmosphere of the heating chamber.

[0068] The apparatus may also be operable to feed the materials into the mixer according to a predefined ratio. Accordingly, the feeders for the feed materials may be metered. It is also possible to continuously feed each of the materials into a continuous mixer at a constant respective feed rate, according to the desired ratio of the materials.

[0069] The apparatus may be operable to move the one or more vessels through the heating chamber in a first direction and induce gas flow through the chamber in a second direction which is opposite to the first direction.

[0070] It will be understood that the invention(s) disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

[0071] As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

[0072] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

[0073] Any of the features which are defined as preferred features of any particular aspect may also have application to any of the other aspects recited above. Brief description of the drawings

[0074] In order that the invention may be more fully understood, one embodiment will now be described by way of example, with reference to the figure(s) in which:

[0075] Figure 1 is a schematic view of an apparatus according to a preferred embodiment of the present invention.

Detailed description of the embodiments

[0076] Figure 1 illustrates a processing apparatus 10, particularly suited to processing a mineral sand particulate according to the specific application described in Australian patent application 2023900482 filed on 24 February 2023 or related PCT application filed on or before 23 February 2024. The processing apparatus includes heating chamber 12 in the form of a tunnel oven 12 of about 60 - 70 m in length. The tunnel oven 12 is nominally divided into a number of zones including a pre-heating zone 14, a holding zone 16 and a cooling zone 18. Depending upon the process carried out in the tunnel oven 12, one or a series of processing steps or reactions may be carried out in each zone. For example, in the pre-heating zone 14, the processes of pre-sulphation and sulphation may occur. These are merely illustrative of the process which may be carried out in the apparatus 10 and the apparatus is not limited to this specific application.

[0077] The pre-heating zone 14 is configured to heat the contents of the vessels 20 therein at the rate of about 3°C per minute. However, the apparatus may be configured to heat the contents at any of the average rates set out above.

[0078] The pre-heating zone 14 is configured to heat the contents of the vessels 20 until the contents of the vessel reached the peak temperature of about 950°C. However, the apparatus may alternatively be configured to heat the composition to any of the peak temperatures as set out earlier in the specification.

[0079] The holding zone 16 is configured to hold the contents of the vessels 20 at the preferred peak temperature of about 950°C, although lower temperatures, such as above about 270° C are also envisaged as outlined in other parts of the specification. [0080] The overall residence time within the preheating zone 14, the holding zone 16 and the cooling zone 18 is about 7 to 9 hours. The residence time within the pre-heating zone may comprise any of the times set out above for heating the composition from an initial temperature to the peak temperature. The peak temperature may be maintained for any duration as set out above.

[0081] The heating chamber may be gas or electric fired. As depicted, the heating chamber 12 is gas-fired with natural gas inlet ports 19 and gas burners 25. The gas burners 25 are disposed above the level of the contents of the vessels 20 and optionally above the vessels 20 per se.

[0082] The processing apparatus 10 is also provided with a plurality of open vessels 20. The open vessels 20 are charged with the contents for processing, enter the tunnel oven 12 at a first end 22, pass in sequence through the tunnel oven 12 and exit the tunnel oven at a second end 24 which is opposite the first end 22 which is adjacent the cooling zone 18. Accordingly, the vessels 20 travel in a first direction from the first end 22 towards the second end 24. The temperature at the second end 24 may be 250° C.

[0083] One by one, the vessels 20 discharge their load after exiting the tunnel oven 12 and continue back to the first end 22 of the tunnel oven 12. Accordingly, the open vessels 20 are arranged in a continuous loop 26. The vessels 20 may be moved on a conveyor 21 or on individual carriages (not shown), for example. The vessels 20 may be pivotable as shown to discharge their load, in the form of billets 23. For instance, the vessels 20 may contain aligned fulcrums which define a pivot axis and the vessels may be sequentially loaded into a pivoting device, with the vessels 20 pivoted about aligned fulcrums.

[0084] Subsequent processing of the solid output may include sawing the billets 23 laterally to remove the undesired portion since the target material may have dropped to the bottom. However, lower ratios of sodium sulfate: zircon reduce the need to do this.

[0085] The tunnel oven 12 also includes an air entry port 28 for entry of air into the tunnel oven 12. A gas exit port 30 is provided adjacent to the first end 22 of the tunnel oven 12. The gas exit port 30 is located within the preheating zone 14. The location of the air entry port 28 and the gas exit port 30 induces a gas flow through the tunnel oven in a second direction from the second end 24 towards the first end 22. Accordingly, the gas flow direction is opposite to the direction of travel of the vessels 20 through the tunnel oven 12. Thus, the air used in the cooling zone 18 can be used as preheated air for gas combustion burners in the preceding zone(s) 14 and optionally 16.

[0086] The apparatus 10 also includes a recycler 32, in the form of a condenser or cooler 33, for condensing any acid, such as sulphuric acid which exits the heating chamber of the tunnel oven 12 as SO3 in gaseous or vapour form. The SO3 may be absorbed in water or absorbed into acid as is known in the art. Either way, the outcome is sulphuric acid which is stored in acid storage vessel 35. Excess water is drawn off from the acid storage vessel 35.

[0087] Additionally, the apparatus 10 is operable such that the preheating zone 14, as well as the holding zone 16 are maintained above the dew point of sulphuric acid to avoid the formation of sulphuric acid within the heating chamber.

[0088] The control system 40 including temperature sensors 42 is operable to maintain the zones at the predetermined temperatures to maintain the contents of the vessels at the aforementioned temperatures, by interfacing with the natural gas input controller 41. The control system 40 may also interface with other sensors 43, for example sensors which determine the gaseous composition in the chamber or the SO3 and/or SO2 concentration. Accordingly, the control system 40 may control the air input

28 and gaseous takeoff, respectively via a controller for the air input 28 and a controller

29 for the gaseous takeoff, to control the atmosphere within the tunnel oven 12.

[0089] The output of the recycler 32 is connected to a mixer 34. The mixer 34 mixes the materials/reactants. The sulphuric acid from the recycler 32 may be supplemented by additional sulphuric acid to make up for losses during processing. For instance, it can be seen that the first feed material to the mixer 34 takes the acid feed from the acid storage vessel 35 as well as fresh acid x.

[0090] The other feed materials introduced are y and z. These may comprise feed materials for the specific process disclosed in our related application, for instance y may comprise sulphate and/or bisulphate. Z may comprise a mineral sand particulate.

Feeders (not shown) may feed metered amounts of materials/reactants x, y, z to the mixer 34. Gravity feed may also be viable. [0091] The mixer 34 includes a mixing vessel, which may include an auger (not shown) for mixing the feed materials/reactants. In a preferred embodiment, the mixer 34 produces a slurry. Accordingly, the mixer 34 is provided with a dispenser 36 to discharge a metered amount of the mixed contents into each vessel 20. The dispenser 36 may comprise a suitable meter 36 for dispensing a predetermined metered amount into each vessel 20.

Claims

1. A processing apparatus, the apparatus including: one or more vessels for containing respective contents; a heating device having predefined zones to heat and cool the contents of the one or more vessels according to a heating regime, the predefined zones including:

A. a preheat zone operable to heat the contents at an average rate within the range of about 2°C per minute to about 7°C per minute until reaching a holding temperature within the range of about 270°C to about 1000°C; and

B. a holding zone to hold the contents at the holding temperature, wherein the holding temperature is the peak temperature of the heating regime; and a moving device to move the vessels sequentially through the zones A and B.

2. The processing apparatus as claimed in claim 1 where the preheat zone is operable to heat the contents at an average rate of about 2 - 5°C/min, preferably about 3°C/min.

3. The processing apparatus as claimed in claim 1 or claim 2 wherein the holding zone is operable to hold the contents at a holding temperature in the range of: about 270°C to 1000°C; or about 500°C to 1000°C; or about 840°C to 1000°C; or about 884°C to 1000°C; or about 900°C to 1000°C.

4. A processing apparatus including: one or more vessels for containing respective contents; one or more heating device operable to heat the contents of the one or more vessels according to a heating regime comprising:

A) heating the contents at an average rate within the range of about 2°C per minute to about 7°C per minute until reaching a holding temperature in the range of about 270°C to about 1000°C; and B) holding the contents at the holding temperature, wherein the holding temperature is the peak temperature of the heating regime.

5. The processing apparatus as claimed in claim 4 wherein the apparatus is operable to heat the contents in A at an average rate of about 2 - 5°C/min, preferably about 3°C/min.

6. The processing apparatus as claimed in claim 4 or claim 5 wherein the holding temperature is in the range of: about 270°C to 1000°C; or about 500°C to 1000°C; or about 840°C to 1000°C; or about 884°C to 1000°C; or about 900°C to 1000°C.

7. The processing apparatus as claimed in any one of claims 1 to 6 wherein the heating device is operable such that the overall residence time of A+ B is in the range of: about 0.5 to about 10 hours; or about 5 to about 7 hours; and residence time in B is about 1 to about 3 hours, preferably about 2 hours.

8. The processing apparatus as claimed in any one of claims 1 to 7 wherein the apparatus/heating device may be operable such that the overall residence time of A+ B+ C is in the range of: about 7 to about 24 hours; or about 7 to about 20 hours; or about 7 to about 15 hours; or about 7 to about 13 hours; or about 7 to 9 hours; or about 8 to 9 hours.

9. The processing apparatus as claimed in any one of claims 1 to 9 wherein burners are used for burning combustible gas and the burners are located in the sidewalls of the heating chamber at a height which is above the height of the contents within the vessels.

10. A processing apparatus including: one or more vessels for containing respective contents; a heating chamber operable to heat the contents of the one or more vessels according to a heating regime, wherein the apparatus is operable to move the one or more vessels through the heating chamber in a first direction and induce gas flow through the chamber in a second direction which is opposite to the first direction; a mixer or mixing station, upstream of the heating chamber to premix the contents before heating; and a recycler for converting at least a portion of gas from the gas flow through the chamber to an acid in liquid form, wherein the recycler is fluidly connected to the mixer or mixing station to discharge the liquid acid thereto.

11. The processing apparatus as claimed in claim 10 wherein the mixer or mixing station dispenses a metered amount of the mixed contents such that each vessel receives a metered quantity of the mixed contents.

12. The processing apparatus as claimed in claim 10 or 11 being operable to feed feed materials into the mixer according to a predefined ratio.

13. The processing apparatus as claimed in any one of claims 10 to 12, wherein the apparatus is operable to maintain at least the heating chamber above the dew point of sulphuric acid.

14. The processing apparatus as claimed in any one of claims 10 to 13, wherein burners are used for burning combustible gas and the burners are located in the sidewalls of the heating chamber at a height which is above the height of the contents within the vessels.

15. The processing apparatus of any one of claims 10 to 14, wherein the or each vessel is comprised of a refractory material comprising silicon carbide or a vessel of another material which is completely or substantially lined or coated, at least internally, with a refractory material comprising silicon carbide, wherein silicon carbide includes siliconised silicon carbide (SiSiC).

16. A processing apparatus including: one or more vessels for containing contents; a heating chamber operable to heat the contents of the one or more vessels according to a heating regime, wherein the apparatus is operable to move the one or more vessels through the heating chamber in a first direction and induce gas flow through the chamber in a second direction which is opposite to the first direction; a mixer or mixing station, upstream of the heating chamber to premix the contents before heating; and a condenser/cooler for creating condensate from at least a portion of gas from the gas flow through the chamber, wherein the condenser/cooler is fluidly connected to the mixer or mixing station to discharge the condensate thereto.

17. The processing apparatus as claimed in claim 16 wherein the mixer or mixing station dispenses a metered amount of the mixed contents such that each vessel receives a metered quantity of the mixed contents.

18. The processing apparatus as claimed in claim 16 or 17, being operable to feed feed materials into the mixer or mixing station according to a predefined ratio.

19. The processing apparatus as claimed in any one of claims 16 to 18 wherein the apparatus is operable to maintain at least the heating chamber above the dew point of sulphuric acid.

20. The processing apparatus of any one of claims 16 to 19, wherein the or each vessel is comprised of a refractory material comprising silicon carbide or a vessel of another material which is completely or substantially lined or coated, at least internally, with a refractory material comprising silicon carbide, wherein silicon carbide includes siliconised silicon carbide (SiSiC).

21. The processing apparatus as claimed in any one of claims 16 to 20, wherein burners are used for burning combustible gas and the burners are located in the sidewalls of the heating chamber at a height which is above the height of the contents within the vessels.

22. A processing apparatus including: a mixer for mixing feed materials to a slurry or suspension, the mixer including a pouring opening or spout, discharge opening, or dispenser for discharging the mixed contents of the mixer into a plurality of vessels such that each vessel receives a metered quantity of the mixed feed materials; a heating chamber having predefined heating or heated zones; the apparatus being operable to move the plurality of vessels through zones within the heating chamber such that the contents of the vessels are subjected to a heating regime according to the temperature and duration in each zone.

23. The processing apparatus as claimed in claim 22 being operable to feed feed materials into the mixer according to a predefined ratio.