A milling apparatus

Abstract

A milling apparatus 10 for grinding material comprising a body 12 defining an internal chamber 14 and comprising an inlet opening. A rotating milling device 18 arranged within the chamber at least partially below the inlet opening comprises at least one impact member 22 to grind the material. A collector plate 28 within the chamber 14 comprises an upper surface for receiving the material, the collector plate 28 defining a longitudinal axis extending parallel to an axis of rotation of the milling device 18. The upper surface is arranged to oppose a portion of the milling device 18 to define a clearance S between the impact member 22 and the upper surface of the collector plate 28. During rotation of the milling device the impact member is configured to impact material on the upper surface of the collector plate 28. The upper surface of the collector plate may comprise a substantially curved portion, the upper surface may comprise at least one rub projecting from the upper surface. A method of grinding a material is disclosed.

Description

FIELD The present teachings relate to a milling apparatus for grinding a material and a method of grinding a material using a milling apparatus. BACKGROUND Typically, milling machines or apparatus use rotating milling devices to grind up material, for example carbonaceous material. Such milling devices typically impact a surface on which the material is situated to break up the material. Carbonaceous milled material is used for a wide range of applications, for example but not limited to coatings, lubricants and synthetic graphite products. Milling devices are known to have inefficiencies, and the sizing of the milled material can be inconsistent. This leads to a reduction in the quality of the milled material, and potentially wasted material. Additionally, milling processes are time consuming. The initial milling process is time consuming due to the inefficient milling, and the lack of quality leads to repeating the milling process, thereby further increasing the time taken to produce the required amount of milled material at a required sizing. The components of these traditional milling devices undergo significant impact during the milling process, and components have been found to wear significantly. This reduces the lifespan of the components, and results in expensive and time consuming maintenance of the milling apparatus. The present teachings seek to overcome or at least mitigate one or more problems associated with the prior art. SUMMARY A first aspect of the present teachings relates to a milling apparatus for grinding a material, the apparatus comprising: a body defining an internal chamber and comprising an inlet opening; a rotating milling device arranged within the internal chamber at least partially below the inlet opening, said milling device comprising at least one impact member configured and arranged to grind the material; a collector plate arranged within the chamber and comprising an upper surface for receiving the material thereon, said collector plate defining a longitudinal axis extending parallel to an axis of rotation of the milling device, wherein the upper surface is arranged to oppose a portion of the milling device to define a clearance between the impact member and the upper surface throughout rotation of the milling device; and wherein the impact member is configured and arranged to impact material on the upper surface of the collector plate, in use. Advantageously, this arrangement increases the efficiency of the milling process. The impact member does not directly impact the collector plate and instead only impacts the material that builds up on the collector plate, which results in "material on material" crushing of the material as the milling device rotates. This improves the efficiency of the milling process and the uniformity of the milled material. The upper surface may comprise an upstream edge and a downstream edge relative to a direction of rotation of the milling device, and the clearance between the impact member and the upper surface may decrease from the upstream edge to the downstream edge. Advantageously, the decreasing of the space between the impact member and the collector plate defines a throat region of minimum separation between the impact member and the collector plate, which facilitates the "material on material" milling process thereby increasing efficiency of the milling process. A minimum clearance between the upper surface and the impact member may be in the range 2m to 30mm. The minimum width of the space defined between the upper surface and the impact member may be in the range 5mm to 15mm, for example approximately 10mm. The upper surface may comprise a substantially curved portion, said curved portion curving about an axis substantially parallel to an axis of rotation of the milling device. This has been found to enable more material to build up on the collector plate, thereby facilitating the "material on material" milling process. The upper surface may comprise an upstream edge and a downstream edge relative to a direction of rotation of the milling device, and the downstream edge may curve in a direction towards the milling device. This arranges the collector plate such that the downstream edge curves in a direction towards the milling device. This has been found to enable more material to build up on the collector plate, thereby facilitating the "material on material" milling process. The upper surface of the collector plate may be continuously curved. The curved portion may define a radius of curvature in the range 150 to 550mm. The curved portion may define a radius of curvature in the range 250 to 450mm, for example 300 to 400mm. Advantageously, providing a radius of curvature within these ranges has been found to optimise the volume of material collected by the collector plate, whilst reducing wear on the collector plate. The curved portion may be substantially dish-shaped or define a recessed region on the upper surface of the collector plate. This has been found to enable more material to build up on the collector plate, thereby facilitating the "material on material" milling process. The upper surface may comprise at least one rib projecting from the upper surface. The at least one rib may define a shoulder, a recess or a groove on the upper surface of the collector plate. This has been found to enable more material to build up on the collector plate, thereby facilitating the "material on material" milling process. Additionally, the rib reinforces the collector plate and increases the structural strength of the collector plate. The at least one rib may project from the upper surface in a direction towards the milling device. The upper surface may comprise an upstream edge and a downstream edge relative to a direction of rotation of the milling device, and the at least one rib may be spaced apart from the downstream edge of the collector plate. Advantageously, the spacing of the rib helps to enable crushed material to fall of the downstream edge of the collector plate. The at least one rib may extend along the longitudinal axis of the collector plate. The at least one rib may extend across an entirety of the collector plate. Advantageously, the elongate groove or recess further increases the space defined between the upper surface and the milling device, and may increase uniformity of the milled material. Additionally, the recess or grooves have been found to reduce wear of the collector plate, thereby increasing its lifespan. The at least one rib may comprise a plurality of spaced apart ribs. The plurality of ribs may define recesses or grooves therebetween on the upper surface of the collector plate. This has been found to enable more material to build up on the collector plate, thereby facilitating the "material on material" milling process. Additionally, the plurality of ribs reinforce the collector plate and increases the structural strength of the collector plate. A distance between adjacent ribs may be in the range 5 to 40mm. The distance between adjacent ribs may be in the range 10 to 30mm. Each of the plurality of ribs may define an upper wall thereof, said plurality of walls arranged along an arc. The upper surface may comprise an upstream edge and a downstream edge relative to a direction of rotation of the milling device, and wherein the arc may be coincident with the downstream edge of the collector plate. The milling apparatus may comprise a reinforcement arrangement configured to reinforce the collector plate. The reinforcement arrangement may comprise at least one plate. Advantageously, the reinforcement arrangement increases the strength of the collector plate, thereby helping to increase the lifespan of the collector plate. The collector plate may be arranged below at least a part of the milling device. Advantageously, the positioning of the collector plate uses the rotation of the milling device to optimise the volume of material collected by the collector plate. The milling apparatus may comprise an impact plate arranged within the chamber upstream of the collector plate relative to a direction of rotation of the milling device such that, in use, material deposited onto the milling device via the inlet opening is directed onto the impact plate. Advantageously, providing an impact plate that is arranged upstream of the collector plate helps to increase the efficiency of the milling process by providing an arrangement by which the material can be broken up prior to being collected on the collector plate. This has been found to help to optimise the consistency of particle size produced by the milling apparatus. The collector plate may be at least partially arranged below the impact plate. The collector plate may be manufactured from a metal alloy. The collector plate may be manufactured from an Ni-hard alloy, for example Cadi Ni-hard. Advantageously, manufacturing the collector plate from an Ni-hard alloy has been found to reduce wear of the collector plate and increase lifespan of the collector plate. A second aspect of the present teachings relate to a method of grinding a material using a milling apparatus, the milling apparatus comprising a body defining an internal chamber and comprising an inlet opening, a rotating milling device arranged within the internal chamber at least partially below the inlet opening, said milling device comprising at least one impact member configured and arranged to grind the material, a collector plate arranged within the chamber and comprising an upper surface for receiving the material thereon, said collector plate defining a longitudinal axis extending parallel to an axis of rotation of the milling device, wherein the upper surface is arranged to oppose a portion of the milling device to define a clearance between the impact member and the upper surface throughout rotation of the milling device, the method comprising the steps of: introducing a material into the chamber via the opening such that the material is deposited on the collector plate; and rotating the milling device relative to the body to only impact the material deposited on the collector plate. The step of rotating the milling device may occur at a rotational speed in the range 900 to 1500rpm. The step of rotating the milling device may occur in the range 1100 to 1300rpm. The material may be a carbonaceous material, for example coke, petroleum coke (petcoke), graphite petroleum coke (GPC), or metallurgical coke (metcoke). BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 is a front view of a milling apparatus according to an embodiment of the present teachings; Figure 2 is an isometric view of a rotating milling device of the milling apparatus of Figure 1; Figure 3 is cross-sectional view of the milling apparatus of Figure 1; Figure 4 is an isometric view of a collector plate of the milling apparatus of Figure 1; Figure 5 is a side view of the collector plate of Figure 4; and Figure 6 is an isometric view of the collector plate of Figure 4. DETAILED DESCRIPTION OF EIMBODIMENT(S) Referring firstly to Figure 1, a milling apparatus generally indicated at 10 is shown. The milling apparatus 10 is suitable for grinding a range of materials, for example carbonaceous materials. Such carbonaceous materials may include coke, petroleum coke (petcoke), graphite petroleum coke (GPC), or metallurgical coke (metcoke). In some embodiments, the milling apparatus may be used for grinding ceramic materials, or any other suitable materials. The milling apparatus 10 includes a body 12 defining an internal chamber 14. The internal chamber 14 is an enclosed space in which material is contained during the milling process. The body 12 includes a substantially cuboidal housing 12, although any suitable shape may be used. In some embodiments, the body 12 is manufactured from a metal alloy, for example stainless steel. The body 12 is configured to house components of the milling apparatus 10 within the internal chamber 14 of the body 12. The body 12 is manufactured from a plurality of walls 12a-e secured together to form the substantially cuboidal housing 12, as is known in the art. The body 12 includes an uppermost wall 12a, a lowermost wall 12b and a plurality of side walls 12c-e extending between the uppermost wall 12a and the lowermost wall 12b. Referring to Figure 2, the milling apparatus 10 includes a rotating milling device 18 arranged within the internal chamber 14. The rotating milling device 18, illustrated in Figure 2, defines an elongate cylindrical body extending along an axis of rotation a-a of the rotating milling device 18. It shall be appreciated that in alternative embodiments, the body may be any suitable shape deviating from substantially cylindrical. The milling device 18 is manufactured from a metal alloy, for example a hardened alloy. The material selected to manufacture the milling device 18 is selected to have sufficient strength and resistance to wear to withstand the impact forces during the milling process. The rotating milling device 18 includes a spindle 20 extending from an end face of the body. A drive mechanism (not shown), for example an electric motor, is connected to the spindle 20 to provide rotational motion to the rotating milling device 18. The spindle 20 is rotationally mounted within the body 12 of the milling apparatus 10, for example via a bearing arrangement, as is known in the art. The spindle 20 in this embodiment is rotationally mounted in the side wall 12c of the body 12, however it shall be appreciated that the spindle 20 may be rotationally mounted anywhere on the body 12, for example in an alternative sidewall. The rotating milling device 18 includes at least one impact member 22 configured and arranged to grind the material. The impact member 22 may be manufactured from a metal alloy, for example an iron or steel alloy. In some embodiments, the impact member 22 may be manufactured using a casting process. Casting the impact member 22 has been found to improve wearability and longevity of the impact member 22. The impact member may be formed from an Ni-hard alloy, for example CADI Ni-hard. This has been found to reduce wear of the impact member 22 and increase the lifespan of the impact member 22. It will be appreciated that in alternative embodiments, the impact member 22 may be manufactured from any suitable material having the required strength, fracture resistance and toughness. In some embodiments, a plurality of impact members 22 are provided and are arranged circumferentially around the rotating milling device 18. The impact member 22 may, by way of example, be at least one blade, hammer, pin or disc. The impact member 22 is mounted to a cylindrical body or surface 18a of the rotating milling device 18. The impact member 22 is fixedly mounted to the rotating milling device 18 such that rotation of the rotating milling device 18 in turn rotates the impact members 22. The impact members 22 are spaced apart from the walls 12a-c such that the impact members 22 are free to rotate during the milling process. The impact members 22 extend radially outwardly from the cylindrical surface 18a of the rotating milling device 18. The impact members 22 may extend in a spiral along the cylindrical surface 18a. The impact members 22 may be arranged in circumferential rows along the cylindrical surface 18a. The impact members 22 extend along the majority of the cylindrical surface 18a of the rotating milling device 18, for example along the entirety of the cylindrical surface 18a. It shall be appreciated that any suitable number of impact members 22 may be provided. Referring to Figure 3, The body 12 includes an inlet opening 16 for material to be placed in the chamber 14. The inlet opening 16 extends into the internal chamber 14 such that material is passed into the internal chamber 14. The inlet opening 16 is secured to the uppermost wall 12a of the body 12. It shall be appreciated that in alternative embodiments, the inlet opening 16 may be located or secured at any suitable location, for example one of the sidewalls 12c-e. The inlet opening 16 may be connected to any suitable feed mechanism, for example a hopper. The feed mechanism helps to ensure consistent and controlled flow of material for optimal milling performance. The feed mechanism may be a gravity-based system or involve the use of a conveyor belt. In some embodiments, a cover (not shown) may be provided to form a cover over the inlet opening 16 during the milling process. This helps to reduce the likelihood of material being expelled from the inlet opening 16 by the rotating milling device 18 during the milling process, thereby improving safety. Additionally or alternatively, the internal chamber 14 may include closures and / or seals to prevent material leakage. The inlet opening 16 is located at least partially above the rotating milling device 18. As such, material received by the inlet opening 16 and through the internal chamber 14 is deposited on the milling device 18. The cover may be omitted in other embodiments. The milling apparatus 10 includes an impact plate 24. The impact plate 24 is arranged to oppose a portion of the milling device 18. The impact plate 24 is arranged within the internal chamber 14 such that material deposited onto the milling device 18 via the inlet opening 16 is directed onto the impact plate 24, in use. The impact plate 24 is therefore positioned with respect to a trajectory of the material imparted by the milling device 18. As the material impacts the impact plate 24 it is broken up. This helps to improve the efficiency of the milling process by providing an initial mechanism by which the material is broken down into smaller parts. This may help to improve the consistency of particle size produced by the milling apparatus 10. In order to withstand the impact forces and abrasion encountered during milling, materials with high strength and wear resistance are used to manufacture the impact plate 24. Such materials may be selected from hardened steel, wearresistant alloys, or other high-strength materials capable of withstanding repeated impacts. The impact plate 24 is at least partially located within the internal chamber 14. The impact plate 24 is at least partially located between the rotating milling device 18 and uppermost wall 12a of the body 12. The impact plate 24 is mounted to the sidewall 12c of the body 12. The impact plate 24 extends beyond the uppermost wall 12a and out of the inlet opening 16. It shall be appreciated that in alternative embodiments, the impact plate 24 may be mounted to an alternative sidewall, or to the uppermost wall 12a of the body 12. In the embodiment of Figure 3, the impact plate 24 is substantially planar. It shall be appreciated that in alternative embodiments, the impact plate 24 may be slightly curved to aid in directing the material towards the milling device 18. The impact plate 24 is mounted to the body 12 by a mounting arrangement 26. The mounting arrangement 26 may include a plate or bracket 26 to mount the impact plate 24 to the sidewall 12c. It shall be appreciated that any suitable mounting arrangement 26 may be used to mount the impact plate 24 to the sidewall 12a. The impact plate 24 and the impact member 22 define a space therebetween throughout rotation of the rotating milling device 18. Put another way, the impact member 22 does not come into contact with the impact plate 24 at any point during the milling process. The impact plate 24 includes an upstream edge 24a and a downstream edge 24b relative to the direction of rotation R of the milling device 18. The space between the impact member 22 and the impact plate 24 decreases from the upstream edge 24a to at or near the downstream edge 24b. The milling apparatus 10 includes a collector plate 28 arranged within the internal chamber 14 and including an upper surface 30 for receiving material thereon. In the embodiment illustrated, the collector plate 28 is at least partially arranged below the impact plate 24. The collector plate 28 is arranged downstream of the impact plate 24 relative to a direction of rotation of the milling device 18. When material is placed into the chamber 14 via the inlet 16, is falls onto the milling device 18. The rotation of the milling device 18 directs the material onto the impact plate 24, where impact of the material on the impact plate 24 causes the material to be broken up. The broken up material then falls onto the collector plate 28, which is arranged at least partially below the impact plate 24. Arranging the collector plate 28 below the impact plate 24 facilitates material being collected on the collector plate 28 after it has impacted the impact plate 24. The upper surface 30 of the collector plate 28 is at least partially arranged below the milling device 18. The collector plate 28 is arranged closer to the lowermost wall 12b of the body 12 than the uppermost wall 12a of the body 12. The positioning of the collector plate 28 uses the rotation of the milling device 18 to optimise the volume of material collected by the upper surface 30. The collector plate 28 is at least partially located between the lowermost wall 12b of the body 12 and the impact plate 24. The collector plate 28 is supported relative to the body 12 by a shelf or ledge 36. The shelf or ledge 36 may extend from one of the sidewalls 12c-e of the body 12. The shelf or ledge 36 is spaced apart from the lowermost wall 12b such that the collector plate 28 is spaced apart from the lowermost wall 12b. The spacing between the lowermost wall 12b and the collector plate 28 enables the upper surface 30 to be in close enough proximity to the rotating milling device 18 to optimise collection of material. The upper surface 30 is arranged to oppose a portion of the milling device 18 to define a space S between the impact member 22 and the upper surface 30 throughout rotating of the milling device 18. Put another way, the impact member 22 does not come into contact with the upper surface 30 at any point during the milling process. During the milling process, milled material is directed by the milling device 18 onto the upper surface 30. The milled material continuously builds up on the upper surface 30. The impact member 22 is configured and arranged to impact material on the upper surface 30 of the collector plate, in use (i.e. during the milling process) but not to impact the collector plate 28. This arrangement increases the efficiency of the milling process because material builds up on the upper surface 30 as the milling device 18 rotates. This improves the efficiency of the milling process and the uniformity of the milled material. The collector plate 28 may be manufactured from a metal alloy, for example an iron or steel alloy. In some embodiments, the collector plate 28 may be manufactured using a casting process. Casting the collector plate 28 has been found to improve wearability and longevity of the collector plate 28. The collector plate 28 may be formed from an Ni-hard alloy, for example CADI Ni-hard. This has been found to reduce wear on the collector plate 28 and increase the lifespan of the collector plate 28. It will be appreciated that in alternative embodiments, the collector plate 28 may be manufactured from any suitable material having the required strength, fracture resistance and toughness. The collector plate 28 defines an elongate body 32. The elongate body 32 extends along an axis parallel to the axis of rotation of the rotating milling device 18 to define a length. The length of the collector plate 28 may be substantially the same as or greater than a length of the rotating milling device 18 (e.g. the impact members) along the same axis. Referring to Figures 4 and 5, the upper surface 30 includes an upstream edge 30a and a downstream edge 30b relative to the direction of rotation R of the milling device 18. A clearance or spacing S (see Figure 3) between the impact member 22 and the upper surface 30 decreases from the upstream edge 30a towards the downstream edge 30. The decreasing of the spacing between the impact member and the collector plate defines a throat region of minimum separation between the impact member and the collector plate, which facilitates the "material on material" milling process thereby increasing efficiency of the milling process. It shall be appreciated that in alternative embodiments, the space S may remain constant from the upstream edge 30a to the downstream edge 30b. A minimum width of the space S defined between the upper surface 30 and the impact member 22 may be in the range 2mm to 30mm, optionally in the range 5mm to 15mm, for example 5mm to 10mm, for example approximately 10mm. Widths within these ranges have been found to improve the quality of the milled material. It will be appreciated, however, that the minimum spacing S may be varied to suit the particular material that is being milled. In some embodiments, the upper surface 30 includes a substantially curved portion. The curved portion curves about an axis substantially parallel to an axis of rotation of the milling device 18. The collector plate 28 may be arranged such that the downstream edge 30b curves in a direction towards the milling device 18. In some embodiments, the upper surface 30 may be continuously curved. For example, the curved portion may extend at least partially from at or near the upstream edge 30a to at or near the downstream edge 30b. In some embodiments, the curved portion is continuously curved and extends along the entirety of the upper surface 30. The radius of curvature of the curved portion is in the range 150mm to 55mm, optionally in the range 250mm to 400mm, for example 300 to 400mm. The continuously curved portion may be substantially dish-shaped, for example to define a recessed region of dish for receiving the material. It shall be appreciated that in alternative embodiments, the curved portion may be a discontinuous curve, and / or the curved portion may extend partially along the upper surface 30. By way of example, the upper surface 30 may include undulations. In further alternative embodiments, the upper surface 30 may be linear, or may include at least one linear portion, and may be angled relative to the milling device 18 so as to define the throat region. In some embodiments, the collector plate 28 includes a base wall 34. The base wall 34 has a thickness in the range 2mm to 30mm, for example 5mm to 20mm. An end of the base wall 34 defines the downstream edge 30b of the collector plate 28. In alternative embodiments, the base wall 34 may be omitted. The upper surface 30 includes at least one rib 38a-e projecting from the upper surface 30. In the embodiment of Figures 3 to 6, five ribs 38a-e are provided, however it shall be appreciated that in alternative embodiments, any suitable number of ribs 38a-e may be provided, for example one, two, three, four, six or any suitable number of ribs 38a-e. It shall be appreciated that in alternative embodiments, the ribs 38a-e may be omitted. The ribs 38a-e define a shoulder, or may define grooves or recesses 40a-d therebetween for receiving material therein. As well as forming these grooves or recesses 40a-d, the ribs 38a-e reinforce the collector plate 28 and increase the structural strength of the collector plate 28, thereby increasing the lifespan of the collector plate 28. The ribs 38a-e may be manufactured as separate components to the collector plate 28 and secured to the upper surface 30. Any suitable securing mechanism may be used, for example welds or fasteners. Each rib projects from the upper surface in a direction towards the milling device. The ribs 38a-e project from the upper surface 30 in a direction substantially perpendicular to the axis of rotation a-a of the milling device 18. The ribs 38a-e project from the upper surface 30 a distance in the range 1mm to 40mm, for example 10mm to 30mm. The ribs 38a-e are elongate along the longitudinal axis of the collector plate 28. In the embodiment shown in Figures 3 to 6, the ribs 38a-e extend across an entirety of the collector plate 28. The ribs 38a-e extend across an entirety of the upper surface 30 in the longitudinal direction. It shall be appreciated that in alternative embodiments, the ribs 38a-e may extend partially along the upper surface 30 in the longitudinal direction, for example over a majority of the upper surface 30 in the longitudinal direction. The ribs 38-e are arranged equidistantly along the upper surface 30 in a direction extending generally from the upstream edge 30a to the downstream edge 30a. A distance D between each rib 38a-e is in the range 5mm to 40mm, optionally in the range 10mm to 30mm. It shall be appreciated that any suitable spacing may be used between the ribs 38a-e, and the spacing may be non-uniform. The or each rib is spaced apart from the downstream edge 30b. In the illustrated embodiment, the rib 38e located closest to the downstream edge 30b is spaced apart from the downstream edge 30b. The spacing of the rib 38e from the downstream edge 30b helps to prevent material from getting stuck between the downstream edge 30b and the impact device 22. The rib 38a located closest to the upstream edge 30a is located at the upstream edge 30a, however it shall be appreciated that in alternative embodiments, the rib 38a may be spaced apart from the upstream edge 30a. In the embodiment of Figure 6, the ribs 38a-e include opposing side walls 42a, 42b connected by an upper wall 42c. For reasons of clarity, only the side walls 42a, 42b and upper wall 42c of the rib 38e are labelled, however it shall be appreciated that the ribs 38a-d are of substantially the same configuration. In alternative embodiments, the ribs 38a-e may be of different configurations. The side walls 42a, 42b taper towards the upper wall 42c. It shall be appreciated that in alternative embodiments, any suitable shape of rib 38a-e may be used. For example, the taper of the side walls 40a, 40b may be omitted. The upper walls 42c of the ribs 38a-e define an arc. The arc defined by the upper walls 42c is discontinuous because the arc is interrupted by each of the grooves 40a-d. The arc defined by the upper walls 42c is coincident with the downstream edge 30b of the collector plate 28. The recess or grooves 40a-d include a substantially curved base wall. The curvature of the base wall has been found to simplify casting of the collection plate 28, thereby improving ease of manufacture of the collection plate 28. The radius of curvature of the base wall of the recess or grooves 40a-d is in the range 1mm to 20mm, optionally 2mm to 10mm, for example 3mm to 7mm. It shall be appreciated that in alterative embodiments, any suitable shape of recess of groove 40a-d may be used. For example, the curvature of the groove or recess 40a-d may be omitted. A maximum width of the grooves or recesses 38a-e may be in the range 5mm to 35mm, for example 10mm to 30mm. Referring to Figure 6, the collector plate 28 includes a reinforcement arrangement 35a-e. The reinforcement arrangement 35a-e include at least one plate 35a-e, for example the five plates 35a-e illustrated in Figure 5. The base wall 34 supports the reinforcement arrangement 35a-e thereon. The plates 35a-e extend transversely from the base wall 34. The plates 35a-e are a right-angled triangle in cross-section. As such, a cross-section of the collector plate 28 is substantially right-angled triangular. The upper surface 30 is secured to the plates 25e-e and to the base wall 34 at the downstream edge 30b. The reinforcement arrangement 35a may include a plurality of plates 35a-e spaced apart and extending along the longitudinal axis of the collector plate 28. For example, there may be first and second plates 35a, 35e located at opposing ends of the collector plate 28, and / or plates 35b-d arranged therebetween. The plates 35a-e reinforce the collector plate 28, thereby increasing the lifespan of the collector plate 28. A method of grinding a material using the milling apparatus 10 of Figure 1 to 6 will be described hereafter. It shall be appreciated that although the method is described with respect to the milling apparatus 10, alternative embodiments within the scope of the milling apparatus 10 outlined above may be used with the described method. Material is inserted into the inlet opening 16 of the body 12 of the milling apparatus 10. The material may be a ceramic or carbonaceous material, for example coke, petroleum coke (petcoke), graphite petroleum coke (GPC), or metallurgical coke (metcoke). The material is deposited on the rotating milling device 18. For example, the milled material may be inserted into the inlet opening 16 using the feed mechanism. The quantity of material inserted into the inlet opening 16 is dependent on the capabilities of the milling apparatus 10 and the desired sizing of the milled material. The milling device 18 is rotated relative to the body 12, for example via the electric motor, to grind the material. The step of rotating the milling device 18 may occur at a rotational speed in the range 900 to 1500rpm, optionally in the range 1100 to 1300rpm. Rotational speeds in these ranges have been found to improve consistency of sizing of the milled material when the milling device 18 is used in combination with the collector plate 28. In embodiments where the impact plate 24 is provided, material is directed towards the impact plate 24 throughout the milling process. Material is deposited on the upper surface 30 of the collector plate 28 such that material is received in the space S defined between the impact member 22 and the upper surface 30. The milling device 18 continues to be rotated such that material continuously builds up on the collector plate 28 and is broken up by the force exerted by the impact member 22 on the material. Although the teachings have been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope as defined in the appended claims.

Claims

1. A milling apparatus for grinding a material, the apparatus comprising:a body defining an internal chamber and comprising an inlet opening;a rotating milling device arranged within the internal chamber at least 5 partially below the inlet opening, said milling device comprising at least one impact member configured and arranged to grind the material;a collector plate arranged within the chamber and comprising an upper surface for receiving the material thereon, said collector plate defining a longitudinal axis extending parallel to an axis of rotation of the milling device, 10          wherein the upper surface is arranged to oppose a portion of the millingdevice to define a clearance between the impact member and the upper surface throughout rotation of the milling device;wherein the impact member is configured and arranged to impact material on the upper surface of the collector plate, in use;15         wherein the upper surface comprises an upstream edge and a downstreamedge relative to a direction of rotation of the milling device, wherein the upper surface comprises at least one rib extending from the upper surface, and wherein the rib closest to the downstream edge is spaced apart from the downstream edge of the upper surface.

202. The milling apparatus according to claim 1, wherein the upper surface comprises an upstream edge and a downstream edge relative to a direction of rotation of the milling device, and wherein the clearance between the impact member and the upper surface decreases from the upstream edge to the downstream edge.25   3. The milling apparatus according to claim 2, wherein a minimum clearancebetween the upper surface and the impact member is in the range 2m to 30mm, optionally wherein the minimum width of the space defined between the upper surface and the impact member is in the range 5mm to 15mm, for example approximately 10mm.30   4. The milling apparatus according to any preceding claim, wherein the uppersurface comprises a substantially curved portion, said curved portion curving about an axis substantially parallel to an axis of rotation of the milling device.

5. The milling apparatus according to claim 4, wherein the upper surface comprises an upstream edge and a downstream edge relative to a direction of rotation of16 09 24the milling device, and wherein the downstream edge curves in a direction towards the milling device.

6. The milling apparatus according to claim 4 or claim 5, wherein the upper surface of the collector plate is continuously curved.5   7. The milling apparatus according to any one of claims 4 to 6, wherein the curvedportion defines a radius of curvature in the range 150 to 550mm, optionally in the range 250 to 450mm, for example 300 to 400mm.

8. The milling apparatus according to any one of claims 4 to 7, wherein the curved portion is substantially dish-shaped or defines a recessed region on the upper 10 surface of the collector plate.

9. The milling apparatus according to any preceding claim, wherein the at least one rib projects from the upper surface in a direction towards the milling device.10.The milling apparatus according to any preceding claim, wherein the at least one rib extends along the longitudinal axis of the collector plate.15   11. The milling apparatus according to claim 10, wherein the at least one rib extendsacross an entirety of the collector plate.12.The milling apparatus according to any preceding claim, wherein the at least one rib comprises a plurality of spaced apart ribs.13.The milling apparatus according to claim 12, wherein a distance between 20 adjacent ribs is in the range 5 to 40mm, optionally in the range 10 to 30mm.14.The milling apparatus according to claim 12 or claim 13, wherein each of the plurality of ribs define an upper wall thereof, said plurality of walls arranged along an arc.15.The milling apparatus according to claim 14, wherein the upper surface 25 comprises an upstream edge and a downstream edge relative to a direction of rotation of the milling device, and wherein the arc is coincident with the downstream edge of the collector plate.16.The milling apparatus according to any preceding claim, comprising a reinforcement arrangement configured to reinforce the collector plate, 30 optionally wherein the reinforcement arrangement comprises at least one plate.16 09 2417.The milling apparatus according to any preceding claim, wherein the collector plate is arranged below at least a part of the milling device.18.The milling apparatus according to any preceding claim, comprising an impact plate arranged within the chamber upstream of the collector plate relative to a direction of rotation of the milling device such that, in use, material deposited onto the milling device via the inlet opening is directed onto the impact plate.19.The milling apparatus according to claim 18, wherein the collector plate is at least partially arranged below the impact plate.20.The milling apparatus according to any preceding claim, wherein the collector plate is manufactured from a metal alloy, optionally an Ni-hard alloy, for example Cadi Ni-hard.

21. A method of grinding a material using a milling apparatus, the milling apparatus comprising a body defining an internal chamber and comprising an inlet opening, a rotating milling device arranged within the internal chamber at least partially below the inlet opening, said milling device comprising at least one impact member configured and arranged to grind the material, a collector plate arranged within the chamber and comprising an upper surface for receiving the material thereon, said collector plate defining a longitudinal axis extending parallel to an axis of rotation of the milling device, wherein the upper surface is arranged to oppose a portion of the milling device to define a clearance between the impact member and the upper surface throughout rotation of the milling device, wherein the upper surface comprises an upstream edge and a downstream edge relative to a direction of rotation of the milling device, wherein the upper surface comprises at least one rib extending from the upper surface, and wherein the rib closest to the downstream edge is spaced apart from the downstream edge of the upper surface, the method comprising the steps of: introducing a material into the chamber via the opening such that the material is deposited on the collector plate; androtating the milling device relative to the body to only impact the material deposited on the collector plate.22.The method according to claim 21, wherein the step of rotating the milling device occurs at a rotational speed in the range 900 to 1500rpm, optionally in the range 1100 to 1300rpm.CXI23.The method according to claim 21 or 22, wherein the material is a carbonaceous material, for example coke, petroleum coke (petcoke), graphite petroleum coke (GPC), or metallurgical coke (metcoke).

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