FIELD

The present disclosure relates to a manufacturing method for manufacture of a spiral trough element for a spiral separator and to a spiral trough element for a spiral separator.

BACKGROUND

Spiral separators are extensively used for the wet gravity separation of particulate solids according to their specific gravity. A spiral separator typically comprises a vertically oriented generally spiral trough, often referred to as a spiral, mounted on a central column. The spiral trough is generally spiral/helical in form, and is sometimes referred to as a spiral sluice. A feed arrangement is provided for feeding a mineral/water slurry to the uppermost part of the spiral trough. Gravity-induced flow of the mineral/water slurry down the spiral trough causes higher specific gravity particles in the slurry to collect in a ‘concentrate stream’ toward the radially inner part of the spiral trough and lighter lower density particles to collect in more radially outer parts of the spiral trough. A spiral separator typically also comprises a collection arrangement, or ‘splitter’, at the bottom of the spiral trough for collecting at least part of the concentrate stream. Most commercially used spiral separators are ‘multiple start’ separators which include multiple intertwined spiral troughs, each provided with a feed arrangement and a collection arrangement as described above.

In the early 1900s commercially used spiral separators were relatively unsophisticated devices utilising simple trough profiles manufactured from flat metal plate affixed together in one half turn sections.

In the 1930, early Humphries spirals were manufactured from rubber tyres cut and spliced to form spiral troughs with multiple turns.

In the 1960s and 1970s, the availability of fibreglass (FRP) manufacturing technology allowed spiral troughs to be manufactured to a higher level of precision. However, FRP is not highly resistant to abrasion caused by prolonged exposure to moving mineral particles in a mineral/water slurry, so FRP spiral troughs were often lined with natural gum rubber sheet to provide a wear surface with enhance wear resistance and thereby prolong the useful life of the spiral troughs.

Since about 1980 most spiral troughs for spiral separators have been manufactured as complete spiral troughs using a composite reverse moulding process. A mould surface normally of five to seven spiral turns is provided. A specially formulated elastomeric polyurethane is sprayed onto the mould surface, and the polyurethane is then backed up with a fibreglass composite structural layer. That is, the fibreglass composite structural layer is formed by applying fibreglass and liquid polymer onto the cured sprayed polyurethane layer and then allowing the fibreglass composite to cure. The spiral trough, normally of five to seven spiral turns, is then separated from the mould surface. The time from beginning spraying of the polyurethane to removal of the spiral trough from the mould may be about 24 hours.

In such spiral troughs the cured sprayed polyurethane layer provides a highly wear-resistant surface which is in use contacted by the mineral slurry, and the fibreglass composite structural layer provides an 'outer shell’ providing structural rigidity and long-term dimensional stability for the spiral trough in use.

In the last decade or so, an alternative approach has been developed in an effort to improve on previously existing technologies from a manufacturing process improvement and/or cost and product performance perspective. This approach comprises moulding relatively small trough segments (of not more than a full turn) of the spiral trough separately and then subsequently assembling the trough segments to form a spiral trough of the desired number of turns.

An example of such an approach is described in US Patent No. 8,813,971, the disclosure of which includes a vertically segmented spiral manufacturing methodology in which the segments for the spiral trough each correspond to about a sixth of a spiral turn and have a height of about a sixth of the spiral pitch. The segments can be stacked vertically, with the trough parts angularly offset, to create a continuous spiral trough inside a support cylinder formed by annular outer parts of the stacked segments. The intent of this process appears to be to facilitate moulding compared to prior art processes such as the composite reverse moulding process described above. The disclosure of this patent extends to alternative forms of trough segment.

Another example of constructing the spiral trough from moulded segments has developed in Asia been used, for example in China, by Alicoco Mineral Technology (www.alicoco.com). In this example plastic injection moulding is used to create the outer shell manufactured in ‘part turn’ segments which are then subsequently assembled together to form multiple turn spirals attached to a centre column for vertical support. A wear liner is manufactured separately and mechanically fastened (but not chemically bonded) to the outer shell.

At least some spiral troughs constructed from separately manufactured injection moulded segments appear to have met with significant market acceptance. An important reason for this appears to be the low cost of such troughs, enabled by the low cost of injection moulding the relatively small segments, compared to the manufacturing cost of the conventional composite reverse moulding process described above.

However, commercially available spiral troughs constructed from separately manufactured injection moulded segments have been found to be susceptible to 'creep’ or cold flow whereby the injection moulded material slowly deforms under persistent mechanical stress, even if the mechanical stress is at a relatively low level. This appears to be due to the poor creep resistance of typical injection moulding grade materials used in their manufacture. Notably, the creep resistance of such spiral troughs has been found to be poor compared to conventional spiral troughs. An issue is that it is not considered practicable to injection mould plastic materials which contain long fibre, high glass ratios such as the glass fibre mat used in the conventional fibreglass manufacturing process used for spiral separator troughs.

As a result, spiral troughs constructed from separately manufactured injection moulded segments have been found to suffer from distortion issues over time. Distortion of the trough renders the resultant gravity separation process less efficient over time and significant problems have arisen in processing plants utilising spirals manufactured using this technology. The segment-based troughs are therefore generally suitable only for low-cost low-efficiency separation plants.

The present inventor has discerned that there is scope to improve the manufacturing of spiral troughs and, alternatively or additionally, scope to provide an improved spiral trough. Accordingly, it is an object of the present disclosure to provide a method of manufacturing a spiral trough element, and/or to provide a spiral trough element, which represent an improvement over, or at least a useful alternative to, known methods and/or spiral trough elements.

Any references to methods, apparatus or documents of the prior art or related art are not to be taken as constituting any evidence or admission that they formed, or form, part of the common general knowledge.

SUMMARY

According to a first aspect of the present disclosure there is provided a method of manufacturing a spiral trough element for a spiral separator, the method comprising: providing a casting mould structure comprising a generally spiral casting mould surface; providing a generally spiral structural component for a spiral trough for a spiral separator; connecting the generally spiral structural component to the casting mould structure to provide a substantially spiral cavity therebetween; applying liquid polymer into the substantially spiral cavity; and allowing the liquid polymer to solidify to thereby form a wear surface part for a spiral trough.

In an embodiment the generally spiral casting mould surface has a shape corresponding to a desired surface shape of a wear surface of a spiral trough for a spiral separator.

In an embodiment the liquid polymer comprises a liquid elastomer.

In an embodiment the liquid polymer comprises a polyurethane.

In an embodiment the method comprises applying a release material to the generally spiral casting mould surface prior to said applying liquid polymer into the substantially spiral cavity.

In an embodiment the method comprises applying a bonding material to the generally spiral structural component prior to said applying liquid polymer into the substantially spiral cavity.

In an embodiment the bonding material comprises a material which is adapted to enhance adherence of the wear surface part and the generally spiral structural component.

In an embodiment the bonding material comprises a material similar to at least one material from which the liquid polymer is constituted and a material similar to at least one material from which the generally spiral structural component is constituted.

In an embodiment the generally spiral structural component comprises a fibre-reinforced composite material.

In an embodiment the generally spiral structural component comprises a fibre reinforced polymer.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising fibres of at least 5 mm in length.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising fibres of at least 25 mm in length.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising fibres of at least 45 mm in length.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer in which a typical fibre length of the fibres is at least 5 mm.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer in which a typical fibre length of the fibres is at least 25 mm. In an embodiment the generally spiral structural component comprises fibre reinforced polymer in which a typical fibre length of the fibres is at least 45 mm.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising one or more mats of fibre material.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising one or more mats of fibre material, one or more of the mats having an area of at least 2500 square millimetres.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising one or more mats of fibre material, one or more of the mats having an area of at least 10,000 square millimetres.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising a mat of fibre material which extends at least approximately half the length of the structural component.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer comprising a mat of fibre material which extends substantially the entire length of the structural component.

In an embodiment the generally spiral structural component comprises a glass fibre reinforced polymer.

In an embodiment the generally spiral structural component is formed using a structural component mould.

In an embodiment the generally spiral structural component is removed from the structural component mould before connecting the generally spiral structural component to the casting mould structure.

In an embodiment the generally spiral structural component is made by a process comprising at least one of: use of a chopper gun; wet lay up; closed mould vacuum moulding; vacuum infusion moulding; light resin transfer moulding.

In an embodiment the method comprises a method of manufacturing a spiral trough element having more than one spiral turn.

In an embodiment the method comprises a method of manufacturing a spiral trough element comprising at least 1.5, or at least 2.0, or at least 2.5, or at least 3.0, or at least approximately 3.5 spiral turns. In an embodiment the generally spiral casting mould surface comprises at least 1.5, or at least 2.0, or at least 2.5, or at least 3.0, or at least approximately 3.5 spiral turns.

In an embodiment the generally spiral structural component comprises at least 1.5, or at least 2.0, or at least 2.5, or at least 3.0, or at least approximately 3.5 spiral turns.

In an embodiment the casting mould structure comprises an elongate post part.

In an embodiment the elongate post part is substantially coaxial with the generally spiral casting mould surface.

In an embodiment the casting mould structure comprises a plurality of mould segments, each comprising a part-spiral casting mould surface.

In an embodiment the mould segments of the plurality of mould segments are mutually connectable so that the part-spiral casting mould surfaces of the respective mould segments together form the generally spiral casting mould surface.

In an embodiment a first mould segment comprises a first part-spiral casting mould surface, a second mould segment comprises a second part-spiral casting mould surface, and first part-spiral casting mould surface is configured differently to the second part-spiral casting mould surface.

In an embodiment a main surface part of the first part-spiral casting mould surface is oriented at a first angle relative to a central axis of the generally spiral casting mould surface, the second part-spiral casting mould surface is oriented at a second angle relative to the central axis of the generally spiral casting mould surface, and the first angle is different to the second angle.

In an embodiment the first and second angles are angles corresponding to respective first and second cross-trough floor angles of a spiral trough.

In an embodiment the casting mould structure further comprises a third mould segment, comprising a third part-spiral casting mould surface.

In an embodiment the third part-spiral casting mould surface is oriented at a third angle relative to the central axis of the generally spiral casting mould surface, and the third angle is different to each of the first and second angles.

In an embodiment the casting mould structure further comprises a fourth mould segment, comprising a fourth part-spiral casting mould surface. In an embodiment the fourth part-spiral casting mould surface is oriented at a fourth angle relative to the central axis of the generally spiral casting mould surface, and the fourth angle is different to each of the first, second and third angles.

In an embodiment said angles relative to the central axis of the generally spiral casting mould surface are angles measured at the axial centre of each respective part-spiral casting mould surface.

In an embodiment said angles relative to the central axis of the generally spiral casting mould surface are angles corresponding to respective cross-trough floor angles of a spiral trough.

In an embodiment said angles relative to the central axis of the generally spiral casting mould surface are angles corresponding to respective cross-trough floor angles of a spiral trough element manufactured by the method.

In an embodiment at least one mould segment comprises an end attachment part for facilitating attachment to another mould segment.

In an embodiment the end attachment part comprises one or more attachment apertures each adapted to receive an attachment member therein.

In an embodiment the attachment part comprises a flange part.

In an embodiment the attachment part comprises an alignment arrangement for facilitating alignment of the mould segment with said another mould segment.

In an embodiment the alignment arrangement comprises one or more alignment apertures each adapted to receive an aligning member therein.

The one or more alignment apertures may comprise the be the one or more attachment apertures. In one alternative one or more alignment apertures which are not attachment apertures may be provided.

In an embodiment the at least one mould segment comprises a side attachment arrangement for facilitating attachment to a central support of the casting mould structure.

In an embodiment at least part of the generally spiral casting mould surface is heated during at least part of a period during which the liquid polymer is allowed to solidify.

In an embodiment the generally spiral casting mould surface is provided with at least one heating element. In an embodiment the casting mould structure is orientated so that an axis of the generally spiral casting mould surface is substantially horizontal, at least during the applying liquid polymer into the substantially spiral cavity.

In an embodiment the casting mould structure is orientated so that an axis of the generally spiral casting mould surface is substantially horizontal, during at least part of the connecting of the generally spiral structural component to the casting mould structure to provide a substantially spiral cavity therebetween.

In an embodiment the casting mould structure comprises a rotation arrangement for rotating at least the generally spiral casting mould surface.

In an embodiment the rotation arrangement comprises a motor.

In an embodiment the rotation arrangement comprises an actuator, operable by a user to effect rotation of at least the generally spiral casting mould surface.

In an embodiment the actuator comprises a controller for the motor.

In an embodiment the actuator comprises a foot-operable actuator.

In an embodiment the rotation arrangement provides one or more preset operations.

In an embodiment the one or more preset operations are selectable by a user.

In an embodiment one or more of said preset operations comprises the rotation arrangement performing or providing one or more of: a predetermined direction of rotation, a predetermined speed of rotation, a predetermined degree of rotation and/or a predetermined final rotational position.

In an embodiment one or more of said preset operations comprises the rotation arrangement performing or providing two or more of: a predetermined direction of rotation, a predetermined speed of rotation, a predetermined degree of rotation and/or a predetermined final rotational position.

In an embodiment one or more of said preset operations comprises the rotation arrangement automatically performing said preset operation.

In an embodiment the generally spiral structural component comprises at least one polymer feed opening.

In an embodiment the generally spiral structural component comprises at least one polymer feed opening associated with each spiral turn of the generally spiral structural component. In an embodiment the method comprises connecting the generally spiral structural component to the casting mould structure so that at least one polymer feed opening is located at a generally uppermost part of the generally spiral structural component.

In an embodiment the method comprises connecting the generally spiral structural component to the casting mould structure so that at least one polymer feed opening is located at a generally uppermost part of each turn of the generally spiral structural component.

In an embodiment the connection of the generally spiral structural component to the casting mould structure provides said substantially spiral cavity between the generally spiral structural component and the generally spiral casting mould surface.

In an embodiment the connection of the generally spiral structural component to the casting mould structure to provide a substantially spiral cavity therebetween comprises relative rotation of the generally spiral structural component with respect to the casting mould structure to facilitate intertwining of the generally spiral structural component and the generally spiral casting mould surface.

In an embodiment the connection of the generally spiral structural component to the casting mould structure comprises clamping the generally spiral structural component to the casting mould structure.

According to a second aspect of the present disclosure there is provided a casting mould structure for attachment thereto of a generally spiral structural component for a spiral trough for a spiral separator, the casting mould structure comprising a generally spiral casting mould surface.

According to a third aspect of the present disclosure there is provided a spiral trough element comprising: a generally spiral structural component for a spiral trough for a spiral separator; and a wear liner providing a wear surface of the spiral trough element; wherein the wear liner comprises a polymer material which has been solidified in a cavity.

In an embodiment the generally spiral structural component comprises fibre reinforced polymer.

According to a fourth aspect of the present disclosure there is provided a method of manufacturing a spiral trough element for a spiral separator, the method comprising: providing a generally spiral structural component for a spiral trough for a spiral separator; applying liquid polymer to form a layer in contact with the generally spiral structural component; and allowing the liquid polymer to solidify to thereby form a wear liner part for a spiral trough element.

In an embodiment the manufactured spiral trough element comprises the generally spiral structural component and the wear liner part.

In an embodiment the manufactured spiral trough element comprises at least two spiral turns of a spiral trough for a spiral separator.

It should be appreciated that features or characteristics of any of the above aspects or embodiments thereof may be incorporated into any of the other aspects. Further, features and characteristics described in relation to any embodiment of a particular given aspect may be considered to be disclosed as being independently applicable to other aspects without requiring importation of other limitations of the said particular given aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments in accordance with the present disclosure will be described, by way of example, in the following Detailed Description of Embodiments which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description of Embodiments is not to be regarded as limiting the scope of the preceding Summary section in any way. The Detailed Description will make reference to the accompanying drawings, by way of example, in which:

Figure 1 is a schematic side view of a spiral separator in accordance with the present disclosure;

Figure 2 is a schematic cross sectional view illustrating a profile of a spiral trough of the separator of Figure 1;

Figure 3 is a schematic side view of a mould apparatus in accordance with the present disclosure;

Figure 4 is a schematic side view of the mould apparatus of Figure 3, illustrating a structural component for a spiral trough being connected thereto;

Figure 5 is a schematic side view of the mould apparatus of Figure 4, illustrating the structural component connected thereto;

Figure 6 is a schematic vertical cross sectional view of part of the mould apparatus of Figure 4, illustrating the structural component being connected thereto; Figure 7 is a schematic vertical cross sectional view of part of the mould apparatus of Figure 4, illustrating the structural component connected thereto to provide a cavity therebetween;

Figure 8 is a schematic vertical cross sectional view of part of the mould apparatus of Figure 4, illustrating the structural component secured thereto by a clamp;

Figure 9 is a schematic end view of part of the mould apparatus of Figure 4, illustrating the structural component secured thereto by a plurality of clamps;

Figure 10 is a schematic vertical cross sectional view generally corresponding to that of Figure seven but illustrating filling of the cavity;

Figure 11 is schematic vertical cross sectional view of part of the mould apparatus of Figure 4, illustrating removal of a manufacture trough element therefrom.

Figure 12 is schematic perspective exploded view illustrating part of a mould apparatus formed from a plurality of segments;

Figures 13 and 14 are schematic perspective exploded views illustrating two of the segments of Figure 12;

Figure 15 to 17 are schematic side views similar to those of Figures 3 to 5, but illustrating an alternative embodiment; and

Figure 18 is a schematic side view similar to those of Figure 4, but showing additional features of the structural component for a spiral trough.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the accompanying drawings embodiments of a method of manufacturing a spiral trough element for a spiral separator will now be described.

Figure 1 illustrates, by way of example, an embodiment of a spiral separator, generally designated by the reference numeral 1, which is an example of a spiral separator in which spiral trough elements manufactured by a method in accordance with the present disclosure are used.

The spiral separator 1, comprises an upright central column 3 supporting first, second and third spirals 5, 5A and 5B, respectively.

The second and third spirals 5A and 5B, are substantially identical to the first spiral 5. As will be appreciated by those skilled in the field of spiral separators for wet gravity separation, the spiral separator 1, having three intertwined spirals, may be regarded as a “three start” separator. The second and third spirals 5A, 5B are arranged so that each respective turn of each of the second and third spirals is substantially below the corresponding turn of the first spiral 5. As the three spirals of the separator 1 are substantially identical, for simplicity and clarity only the first spiral 5 will be described in detail, and it should be appreciated that where only one spiral is explicitly described or illustrated, the other spirals correspond. It should also be appreciated that applicability of the present disclosure is not limited to spiral separators having three spiral troughs, but is also applicable to spiral separators having one, two, four or more spirals, that is, generally, to single-start and to multiple-start spiral separators.

A conventional arrangement (not shown), for example including a powered pump, is provided for admitting a mineral/water slurry or pulp to each spiral via a feedbox, for example feedbox 7, at a predetermined rate, at or adjacent the top of the spiral. The feedbox 7 may be of a conventional type.

A splitting arrangement 9, which may be a conventional splitting arrangement, is provided at the bottom of each spiral 5, 5A, 5B for splitting the descending slurry stream into fractions (for example corresponding to radially distributed streams or bands) and recovering certain desired fractions. In the illustrated embodiment the splitting arrangement 9 comprises splitters (not shown) and off-take channels 9A, 9B, 9C provided to split and off-take the descending slurry flow into a concentrates fraction, a middlings fraction and a tails fraction, respectively.

The spiral separator 1 may be regarded as a two-stage separator, comprising a first stage 30 and a second stage 50.

The first stage 30 comprises a first spiral (or, equivalently, ‘helical’) trough part of each spiral, for example a first spiral trough part 200 of the first spiral 5. The first spiral trough part 200 is an example of a spiral trough element which can be manufactured by an embodiment of a method in accordance with the present disclosure.

In the illustrated embodiment the first spiral trough part 200 is approximately 3.5 turns from a pulp feed point (not shown) where pulp is fed onto the first spiral trough part 200 by the feedbox 7 to a concentrate off-take point 34 provided at or adjacent the downstream end of the first spiral trough part 200, that is, substantially at the end of the first stage 30.

Directly downstream of the first stage 30 there is provided a mixing, or ‘repulping’, region 40 which prepares the slurry which exits the first stage 30 for entry to the second stage 50. The mixing or ‘repulping’ region 40 (henceforth referred to as the mixing region 40) is provided in order to avoid sluggish, high-density slurry, that has become somewhat dewatered during the first stage, entering the second stage in that sluggish, dewatered state. A concentrates stream is removed from each spiral at a take-off point (not shown) at or close to the downstream end of the first stage 30 upstream of the mixing or repulping.

The second stage 50 is directly downstream of the mixing region 40, and comprises a second spiral trough part 200A of the first spiral 5. The second spiral trough part 200A is approximately 3.5 turns from a pulp feed point (not shown), where pulp exits the mixing region 40 and is fed onto the second spiral trough part 200A, to an off-take point at the splitting arrangement 9. The second spiral trough part 200A is an example of a spiral trough element which can be manufactured by an embodiment of a method in accordance with the present disclosure, and may be substantially identical to (or, if desired, somewhat different to) the first spiral trough part 200. In an embodiment the first and second spiral trough parts 200, 200A of the first spiral 5 are substantially identical, and also substantially identical to corresponding first and second spiral trough parts of the second and third spirals 5A, 5B.

If desired, further stages may be provided. A concentrates offtake may (and typically will) be provided at or adjacent the downstream end of each stage, and a mixing or repulping, region may (and typically will) be provided immediately upstream of each of the second and subsequent stages. Mixing or repulping of a mineral slurry prior to treatment on a second, or subsequent, stage spiral separator is known per se, and any suitable arrangement may be used to implement mixing and/or repulping in the mixing region 40.

In the illustrated embodiment the mixing region comprises a mixing module for each spiral, for example mixing module 140 of the first spiral 5, which is a modular unit which is manufactured separately from the first and second spiral trough parts 200, 200A. The mixing module 140, in use, is located ’in-line’ between a downstream end of the first spiral trough part 200 and an upstream end of the second spiral trough part 200A, to provide a substantially continuous configuration of the first spiral 5. The mixing module 140 is thus provided with upstream-end and downstream end flanges 142, 144, for connecting to complementary flanges (not shown, but described in due course) at the downstream end of the first spiral trough part 200 and the upstream end of the second spiral trough part 200A, respectively. The respective flanges include complementary alignment features to aid assembly and accurate relative location/alignment of the mixing module 140, first spiral trough part 200 and second spiral trough part 200A. For example, the flanges may be configured with arrangements of apertures positioned so that they align only when the location/alignment of the parts is correct, and which also allow connection when the location/alignment is correct, by use of fasteners in the apertures. Of course, connection and location/alignment arrangements other than flanges and apertures may be substituted. In the illustrated embodiment, the feedbox 7, and splitting arrangement 9 are (similarly to the mixing module 140) formed as modular units, arranged to be connected to an upstream or downstream end, respectively, of a spiral trough part of the separator 1 , and are provided with suitable flanges, or other connection arrangements which assist location and alignment. Thus the first and second spiral trough parts 200, 200A may be identical, each having an upstream- end connection adapted to be connected to, and aligned with, either one of the feedbox 7 and the downstream end of the mixing module 140, and each having a downstream-end connection adapted to be connected to, and aligned with, either one of the splitting arrangement 9 or the or the upstream end of the mixing module 140.

Figure 2 illustrates schematically, in partial radial cross section, the radial cross sectional structure of an embodiment of the first spiral trough part 200 of the separator 1 of Figure 1 , which is an example of a trough element manufactured in accordance with the present disclosure.

In the illustrated embodiment the first spiral trough part 200 comprises a fibre reinforced polymer structural component 210 which provides an ‘outer shell’ providing structural rigidity and long-term dimensional stability for the spiral trough part 200 in use. The first spiral trough part 200 further comprises a highly wear resistant wear liner 240.

The structural component 210 provides a radially outer wall part 212 which as illustrated extends substantially vertically. The structural component 210 further provides a radially inner connection part 214, which as illustrated projects downwardly for facilitating connection to the central column 3, and an inclined trough floor part 216 which extends at least most of the radial distance between the radially outer wall part 212 and the connection part 214. An additional trough feature 218 may be provided between the trough floor part 216 and the connection part 214. The radially outer wall part 212 of the structural component 210 provides a radially outer wall part of the trough 200.

The wear liner 240 substantially overlies the structural component 210, and provides a wear surface 242 of the spiral trough part 200. In the embodiment illustrated in Figure 2 the wear surface provides a radially outer wall surface part 243, a trough floor surface part 246 and an additional feature surface part 248. The wear liner also provides an in-turned lip 250 which projects inwardly from the top of the radially outer wall part 212 of the trough 200. In use, the in-turned lip 250 assists in preventing parts of the mineral/water slurry flowing over the radially outer wall part 212 of the trough 200, in use. This, in turn, allows the radially outer wall part 212 of the trough 200 to be reduced in height (compared to a radially outer wall part of a similarly configured trough without an outer in-turned lip 250) which can assist in allowing more spirals to be fitted in a given height, dictated by the pitch of the spirals, in a spiral separator. It is believed that the height reduction, at least in some embodiments of spiral separator, will enable fitting of four spirals rather than three, and that a four-start spiral separator rather than a three-start spiral separator can therefore be provided. Provision of a four start spiral separator, instead of a three-start spiral separator which takes up the same amount of space in a minerals processing facility can effectively increase the amount of slurry that can be processed in a given area and height by approximately a third, thus providing a commercially valuable benefit.

The wear surface 242 comprises the surface on which the mineral/water slurry flows and upon which separation occurs. Thus while the shape of the wear surface corresponds generally to the shape of the underlying surface of the structural component 210, accuracy in the shape of the wear surface 242 is of great importance to effective separation performance, while accuracy in the shape of the underlying surface of the structural component 210, being an internal surface which has no contact with the mineral slurry is relatively unimportant to effective separation performance, provided inaccuracies or variations therein do not adversely affect accuracy in the shape of the wear surface 242. Thus the level of accuracy in forming the structural component 210 does not need to be as high as the level of accuracy in forming the wear surface 242 of the wear liner 240.

It will be appreciated that while an example profile is illustrated in Figure 2, the profile, including the pitch of the radially outer wall part 212, the pitch of the connection part 214, the cross-trough slope of the trough floor part 216, the down-trough slope of the trough floor part 216, and the configuration of additional trough feature 218 may be varied, as desired, to provide different trough configurations providing different separation characteristics. Indeed, one or more of these features may vary substantially between different turns in a single spiral trough part. In the illustrated embodiment the additional trough feature 218 comprises a raised platform part which extends slightly above the adjacent part of the trough floor part 216, but it will be appreciated that other types of feature, such as for example a radially inner gutter (not shown), may additionally or alternatively be provided as the additional trough feature 218.

In the illustrated embodiment, the wear liner 240 has been cast, from poured liquid polymer material, onto the previously formed structural component 210. The present disclosure teaches methods of manufacturing trough parts such as, for example, spiral trough part 200.

With reference to Figures 3 to 11 in particular, an embodiment of a method of manufacturing a spiral trough element, for example first spiral trough part 200 illustrated in Figure 2, will be described. Figure 3 illustrates, in schematic side view, an embodiment of a casting mould structure in the form of a casting mould apparatus 300. The casting mould apparatus 300 comprises a casting mould part 302. In the illustrated embodiment the casting mould part 302 is generally helical or spiral, and comprises 3.5 spiral turns. The casting mould part 302 may have a helical diameter of between about 600 mm and about 700 mm, although other diameters are, of course possible.

The casting mould part 302 is mounted on, and supported by a central post 304, which is preferably formed of metal. The casting mould part 302 provides a generally spiral casting mould surface 306, which has a has a shape corresponding to a desired surface shape of a wear surface of wear liner of a spiral trough for a spiral separator.

The central post 304 is supported by a support structure 308 of the casting mould apparatus 300. The support structure 308 comprises an engaging arrangement 310 for engaging a floor surface (not shown) and preferably for secure attachment to the floor, for example by bolts or the like (not shown). The support structure 308 further comprises a support body which extends upwardly from the engaging arrangement 310, and which in the illustrated embodiment is in the form of a support column 312. The central post 304 is supported at an upper part of the support column 312, for example by passing through a through hole 314 of the support column 312, although, of course, other arrangements for supporting the central post 304 relative to the support body may be used. In the illustrated embodiment the support structure 308 further comprises an angled brace member 316, attached to a part 318 of the support column 312 which is spaced apart from the central post 304, and to a part 320 of the central post 304 which is spaced apart from the support column 312.

The central post 304 may be rotationally fixed relative to the support body (support column 312) or may be supported by the support body such that the central post is rotatable, substantially about its axis.

Figures 3 to 5 illustrate an embodiment in which the central post 304 is rotationally fixed relative to the support body (support column 312), although it should be appreciated that the embodiment of Figures 3 to 5 could be varied to provide for the central post to be rotatable substantially about its axis. For example, the central post 304 could be rotatably mounted in the through hole 314 using appropriate bearings in the through hole 314, and an arrangement for manually rotating the central post 304, such as a handle (not shown) extending transversely relative to the support post provided (for example) at or adjacent the supported end 322 of the central post 304. The handle could be a manually operable wheel. A brake arrangement (not shown) may be provided to prevent undesired rotation of the central post 304. While an example of a variation providing for manual rotation of the central post 304, and thus of the generally spiral casting mould surface 306, may be used, an embodiment providing powered rotation will be described in due course with reference to Figures 15 to 17. In an embodiment in which the central post is rotatable, the angled brace member 316 may be omitted, or the connection of the angled brace member 316 to the part 320 of the central post 304 may be configured to accommodate relative rotation while still providing support (for example, by providing a suitable ring bearing between the central post 304 and a collar which surrounds the central post 304 and is attached to the angled brace member 316).

The casting mould apparatus 300 may further comprise a first or proximal end plate 324 providing a casting mould proximal end surface part 326 (provided on the opposite side of the end plate 324 to that visible in Figures 3 to 5, and thus indicated using a dashed lead line). The proximal end plate 324 is provided on a proximal end 325 of the casting mould part 302, being an end thereof which is proximal the support structure 308.

The casting mould apparatus 300 is further provided with heating elements 323, illustrated schematically in Figure 3. In an embodiment the heating elements comprise electrically powered resistive heating mats bonded to an external surface 328 of the casting mould part 302. The heating mats may be provided over as much of the external surface of the casting mould part 302 as is practicably reasonably in order to provide substantially uniform temperature throughout the casting mould part 302.

As illustrated schematically in Figure 4, a generally spiral structural component, which in the illustrated embodiment corresponds to structural component 210 illustrated in Figure 2, can be threaded on to the casting mould apparatus 300.

The casting mould part 302 is preferably preheated, using the heating elements 323, before beginning threading of the structural component 210 onto the casting mould apparatus 300.

The structural component 210, in the illustrated embodiment, comprises a fibre-reinforced composite material, such as a suitable fibre reinforced polymer (FRP), and in a particular embodiment a glass fibre reinforced polymer.

The structural component 210 may be manufactured using any suitable production process. As explained above, the level of accuracy in forming the structural component 210 does not need to be as high as the level of accuracy in forming the wear surface 242 of the wear liner 240, so low-cost FRP (fibreglass) manufacturing process can be utilised. It will be appreciated that as the structural component 210 is required to support the wear liner 240 for extended periods, and deformation of the structural component 210 may cause highly undesirable deformation of the wear surface 240 of the wear liner 240, high dimensional stability and high creep resistance of the structural component 210 is important. However, it is believed that sufficiently high dimensional stability and creep resistance can readily be achieved in FRP materials such as fibreglass composite using low-cost FRP manufacturing processes.

The structural component 210 may, for example, be manufactured using a structural component mould, and may suitably be manufactured using closed mould vacuum or light resin transfer moulding techniques (light RTM). Other FRP forming processes could alternatively be used including, for example one or more of: use of a chopper gun; wet lay up; vacuum infusion moulding; and/or light resin transfer moulding. Use of a relatively long fibre length assists in providing desired structural/mechanical characteristics, including high creep resistance. In an embodiment a typical fibre in the FRP preferably has a fibre length of at least about 40mm or 50mm, although fibre length of at least 20 mm or even at least 5 mm may be sufficient, depending on the circumstances. The fibres may be provided (for example at the moulding stage) in the form of one or more fibre mats (known per se). One or more pieces of fibre mat, for example with an area of at least 2500 square millimetres, or at least 10,000 square millimetres may be used. In an embodiment, for example (but not limited to) a structural component produced by resin transfer moulding, a mat of fibre material which extends substantially the entire length of the structural component may be used.

The structural component 210 may be manufactured at a location remote from the casting mould apparatus 300, and transported to the location of the casting mould apparatus 300 from its place of manufacture, which may, for example be in a different country to the location of the casting mould apparatus 300.

Threading of the generally spiral structural component 210 on to the casting mould apparatus 300 can be regarded as intertwining the spiral structural component 210 with the casting mould part 302. Due to the spiral shapes of the casting mould part 302 and the structural component 210, positioning of the structural component 210 so that it is intertwined with the casting mould part 302 is performed by a combination of rotation of the structural component 210 about its axis, and movement of structural component 210 in its axial direction. The movement of a first, or leading, end 402 of the structural component 210 is illustrated by broken line arrow 401 in Figure 4. The structural component 210 also has a second or trailing end 403.

It will be appreciated that it is the relative movement of the structural component 210 and the casting mould part 302 (or the generally spiral casting mould surface 306) which is important. In the embodiment of Figure 4, in which the casting mould part 302 (or the generally spiral casting mould surface 306) is rotationally and axially stationary, this relative movement corresponds the actual movement of the structural component 210, although alternatives will be described in due course.

In the illustrated embodiment the structural component 210 comprises 3.5 spiral turns. In the illustrated embodiment the structural component 210 comprises substantially a structural component of a trough intended to be used to extend substantially the full length of a separation stage of a spiral separator. Spiral separators having stages comprising spiral troughs which are 3.5 turns in length are described in the present applicant’s Australian Provisional Patent Application No. 2019900497, and PCT Application Publication Number WO/2020/163893 (entitled SPIRAL SEPARATORS AND PARTS THEREFORE) claiming priority from that provisional patent application, and the full disclosure of those applications is incorporated herein by reference. It should be appreciated that the spiral troughs or trough parts described in the aforementioned patent applications could be manufactured in accordance with the present disclosure, although this has not been effected at the time of writing, or by other manufacturing methods, such as by the composite reverse moulding process described above. It should be appreciated that embodiments of methods in accordance with the present disclosure are applicable to spiral troughs with a smaller or greater number of turns, for example (but not limited to) between about 2.5 and 7 spiral turns, and to modular spiral trough lengths which are adapted to be connected together to form a trough corresponding to substantially the full length of a stage of a spiral separator, for example (but not limited to) modules comprising trough parts of 1.75, or 2.5, spiral turns adapted to be connected to modules of similar trough length to provide a spiral trough of a separator stage with a trough of 3.5 or 5 spiral turns respectively. The term ‘spiral trough element’ as used herein, is intended to relate to (but not to be limited to) both spiral trough parts which have a number of turns corresponding substantially to the number of turns of a spiral separator stage and spiral trough modules which are adapted to be connected to other spiral trough modules to provide a spiral trough with a number of turns corresponding substantially to the number of turns of a spiral separator stage. The term ‘spiral trough element’ as used herein is also intended to relate to spiral trough parts which have a number of turns greater than the number of turns of a spiral separator stage, for example anticipating that such a spiral trough part may provide more than one stage of a spiral separator and be divided into different separator stages by a concentrate off-take and/or mixing/repulping region provided on or in an intermediate part of the spiral trough part.

In the position shown in Figure 4 the structural component 210 is illustrated as having been threaded onto the casting mould part 302 by 1.5 turns, with 2 full turns still required to fully thread the structural component 210 onto the casting mould part 302. The structural component 210 provides a fill spout arrangement 404 on each respective turn thereof.

Figure 4 also illustrates a second, or distal, end plate 324A providing a distal end surface part 326Afor providing a casting mould distal end surface part 326A (provided on the opposite side of the distal end plate 324A to that visible in Figures 4 and 5, and thus indicated using a dashed lead line). The distal end plate 324A is attachable to a distal end 325A of the casting mould part 302, being an end thereof which is distal the support structure 308. The distal end plate 324A and the distal end 325A of the casting mould part 302 are provided with an end plate connection arrangement, for example complementary apertures 327, for allowing attachment of the distal end plate 324A to the distal end 325A after intertwining of the structural component 210 and the casting mould part 302.

Figure 5 illustrates schematically the structural component 210 and the casting mould part 302 after threading (intertwining) of the structural component 210 onto the casting mould part 302, and also after any required or desired further axial positioning of the structural component 210. Figure 5 also illustrates schematically the distal end plate 324A attached to the distal end 325A to provide the casting mould distal end surface part 326A on the casting mould part 302

With the structural component 210 and the casting mould part 302 positioned as illustrated in Figure 5 a substantially spiral cavity (not shown in Figure 5, but designated by reference numeral 700 in, for example, Figure 7) is provided between the structural component 210 and the generally spiral casting mould surface 306. The cavity is closed off at its longitudinal ends by the casting mould proximal and distal end surface parts, 326, 326A, which are provided by the proximal and distal end plates 324, 324A. That is, the respective first and second ends 402, 403 of the structural component 210 engage the respective proximal and distal end plates 324, 324A so that the casting mould proximal and distal end surface parts 326, 326A bridge the distance between the respective first and second ends 402, 403 of the structural component 210 and the casting mould part 302.

As will be described below in more detail, the cavity is filled with liquid polymer, which may comprise an elastomer material such as polyurethane, and the liquid polymer is allowed to solidify to provide an abrasion resistant wear liner, for example corresponding to wear liner 240 illustrated in Figure 2, corresponding to the shape of the cavity and firmly bonded to the structural component 210. Thus, a spiral trough element, for example the first spiral trough part 200, comprising the structural component 210 and the abrasion resistant wear liner 240 is manufactured. Figure 6 illustrates in schematic partial medial axial cross section, the structural component 210 fully rotationally threaded on to the casting mould part 302, but displaced axially slightly from the casting mould part 302, for clarity. The illustrated profile of the profile of the structural component 210 comprises the radially outer wall part 212, radially inner connection part 214, trough floor part 216 and additional trough feature 218, as described above with reference to Figure 2. The structural component 210 has an internal surface 601, which comprises internal surfaces of the radially outer wall part 212, the trough floor part 216 and the additional trough feature 218. It will be appreciated that the internal surface extends the entire length of the generally spiral structural component, and is therefore a generally spiral surface.

The structural component 210 further comprises a helical flange 602 which projects radially outwardly from a distal (in use upper) part of the radially outer wall part 212.

As illustrated in Figure 6, each fill spout arrangement 404 comprises a tubular attachment part 604, for attachment of a polymer (e.g. polyurethane) feed tube (not shown) and an internal bore 606, which is effectively an aperture which extends through the radially outer wall part 212 of the structural component 210.

As illustrated in Figure 6, the casting mould surface 306, has a shape corresponding to a desired surface shape of a wear surface 242 of wear liner 240. Thus the casting mould surface 306 provides an outer wall mould surface part 608 (corresponding to the shape of the radially outer wall surface part 243 of the wear liner 240), a trough floor mould surface part 610 (corresponding to the shape of the trough floor surface part 246 of the wear liner 240) and an additional feature mould surface part 612 (corresponding to the shape of the additional feature surface part 248 of the wear liner 240). The casting mould surface 306 also provides a recess surface 614 with a shape that corresponds to the surface shape of the in-turned lip 250.

The casting mould part 302 provides a helical flange 640 complementary to the helical flange 602 of the structural component 210.

Before being threaded onto the casting mould part 302 the entire internal surface 601 of the structural component 210 is primed with a suitable primer to improve adhesion between the structural component 210 and the wear liner 240. A small area of primer is illustrated schematically in Figure 6, and designated by the reference numeral 650. In an embodiment in which the structural component 210 comprises fibreglass FRP and the wear liner comprises polyurethane a polyurethane-based primer can suitably be used. Also before the structural component 210 is threaded onto the casting mould part 302, the entire casting mould surface 306 has a release agent applied thereto, to assist separation of the wear liner 240 from the casting mould part 302. A small area of release agent is illustrated schematically in Figure 6, and designated by the reference numeral 652.

Figure 7 illustrates in schematic partial medial axial cross section, the structural component 210 fully rotationally threaded on to the casting mould part 302, and positioned so that the helical flange 602 of the structural component 210 abuts the helical flange 640 of the casting mould part 302. Further, in the position illustrated in Figure 7 the respective first and second ends 402, 403 of the structural component 210 engage the respective proximal and distal end plates 324, 324A. This positions the structural component 210 relative to the casting mould part 302, as desired, to provide a spiral cavity 700 between the structural component 210 and the casting mould part 302 and, more specifically, between the spiral internal surface 601 of the structural component 210 and the spiral casting mould surface 306. The distance between the spiral internal surface 601 of the structural component 210 and the spiral casting mould surface 306 corresponds to the thickness of the wear liner, and the casting mould part 302 (and/or the structural component 210) can be configured to provide the desired thickness. In a particular embodiment a desired thickness of the wear liner is between about 3 mm and about 5 mm.

As illustrated in Figure 8, the helical flange 602 of the structural component 210 can be clamped to the helical flange 640 of the casting mould part 302 to secure the relative positions of the structural component 210 and the casting mould part 302 and to assist in providing fluid tight integrity of the spiral cavity 700. Any suitable clamping arrangement or clamping devices, illustrated schematically and designated by the reference numeral 800, may be used.

Figure 9 is a schematic end view, along the axis of the central post 304, from the support structure end, illustrating that a large number of clamping devices 800 may be used to secure the relative positions of the structural component 210 and the casting mould part 302.

With the structural component 210 securely clamped to the casting mould part 302 it has been found that the connection part 214 is retained in sufficiently close and secure abutment with the central post 304 to provide sufficient fluid tight integrity of the cavity 700, so that no additional securement, or sealing, between the structural component 210 and the central post 304 is required. It will be appreciated that the central post 304 is, at least in this embodiment, is dimensioned to be of the same diameter as a central column 3 of a spiral separator to which the trough part 200 is designed to be attached.

Figure 10 illustrates insertion of liquid polymer 1000 into the cavity 700 by insertion through a fill spout arrangement 404. In an embodiment the liquid polymer is inserted through all of the fill spout arrangements 404 substantially simultaneously. The fill spout arrangements 404 are positioned at the parts of the respective spiral turns which are topmost (highest) during filling of the cavity. Unnecessary pressurisation of the liquid polymer in the cavity 700 is considered undesirable as excessive pressure in the cavity may cause deformation or deflection of parts of the structural component 210. Such deformations or deflections would result in a greater thickness of the cavity 700 and correspondingly greater thickness of the wear liner 240 at the deformed or deflected regions, resulting in irregularities or shape variations in wear liner in the final demoulded product, which would likely adversely affect separation performance.

The horizontal orientation of the structural component 210 and casting mould part 302 during insertion of the liquid polymer 1000 into the cavity 700 limits the depth of liquid polymer 1000 to substantially the helical diameter of the cavity 700, thereby limiting the hydrostatic pressure within the cavity 700. If the structural component 210 and casting mould part 302 were oriented vertically during insertion of the liquid polymer, the depth of the liquid polymer the cavity 700 would be substantially the axial length of the spiral cavity 700, which is substantially greater than (and approximately double in the illustrated embodiment) the helical diameter, resulting in a correspondingly higher hydrostatic pressure.

Further, to assist in avoiding unnecessary pressurisation, the liquid polymer 1000 is fed relatively gently into the cavity 700 over a period of several minutes (for example between about 2 and 10 minutes, and in an embodiment between about 3 and 8 minutes) rather than being rapidly forced into the cavity 700 under substantial pressure. In an embodiment approximately 10 kg to 20 kg of liquid polymer is used to fill the cavity 700, inserted at a rate of between about 2 kg per minute and about 4 kg per minute.

Further, the cavity 700 is filled only to a free air surface at the top thereof.

The liquid polymer is then allowed to solidify to form the wear liner 240, strongly bonded to the structural component 210. After sufficient solidification the clamps 800 and distal end plate 324A are removed and the wear liner 240, strongly bonded to the structural component 210 is stripped from the casting mould surface 306, facilitated by the release agent 652, as illustrated in Figure 11. It will be appreciated that the combined the wear liner 240 and structural component 210, as illustrated in Figure 11 corresponds substantially to the trough part 200, as illustrated in Figure 2 (although the orientation is different and the combined the wear liner 240 and structural component 210, as illustrated in Figure 11, has not yet been attached to a central column 3 of a spiral separator).

The combined wear liner 240 and structural component 210 is then unthreaded or unwound from the casting mould part 302, and a spiral trough element has been manufactured. The casting mould apparatus 300 may then be used to manufacture another spiral trough element.

It may be observed that it is not essential that the shape of the internal surface 601 of the structural component 210 corresponds substantially to the shape of the wear surface 242 of the wear liner 240. However, this is considered desirable in order to provide a wear liner 240 of reasonably uniform thickness, and to avoid using an unnecessarily large amount of liquid polyurethane to form the wear liner 240, which would incur unnecessary cost and add unnecessary weight.

It will be appreciated, however, that the shape and size of the helical flange 602 of the structural component 210 should complement the shape and size of the helical flange 640 of the casting mould part 302 with reasonable accuracy so that it can be clamped thereto (as discussed above) without excessive deformation of the structural component 210, and that the connection part 214 of the structural component 210 should be manufactured with reasonable dimensional accuracy so that it can be retained in adequately close and secure abutment with the central post 304 (as discussed above). Further, it will be appreciated that the connection part 214 will, in use, be important in attaching the manufactured trough to the central post/column of a spiral separator, so it should be formed so that such attachment does not significantly adversely affect the shape and function of the trough, including the working surface of the liner.

(It will be appreciated that at least some similar considerations apply to the previously used approach, as set out in the background section, in which troughs are manufactured as complete spiral troughs using a composite reverse moulding process. That is, the attachment of the trough, in use, to the central column of a spiral separator, must not be such as to unduly deform the trough (e.g. away from its as laid-up shape) in a manner, or to an extent, which would significantly adversely affect the shape and function of the trough.)

One way (not illustrated) of manufacturing an FRP structural component comprises making the mould/tooling for the structural component, based at least partly on the casting mould part 302, including the casting mould surface 306, and appropriate parts of the helical flange 640 and central post 304. In an embodiment, starting with the casting mould part 302, a layer is added (mainly onto the casting mould surface 306) to represent/form the cavity 700 that is required (so that the added layer may be regarded as corresponding to the shape of the desired wear liner). The layer added to the aluminium casting mould to represent/form the cavity may, for example, be made up of moulding wax and, if desired, one or more laminate layers in appropriate positions. The relevant part of the combined casting mould part 302 and the added layer provide the reverse of the shape required of the relevant parts of the structural component, so the mould/tooling for the structural component can be made based on this shape, for example in a manner that is conventional per se and which will be appreciated by the person skilled in the relevant field, in order to achieve the aforementioned complementary shapes of the structural component 210 and the casting mould part 302.

A liquid polymer comprising polyurethane suitable for use as described should desirably be high performance elastomeric polyurethane with low viscosity to facilitate filling the narrow cavity 700. Viscosities of approximately or below 1000 cps (or millipascal seconds) at 80 degrees Centigrade are considered sufficiently low for effective use, but lower viscosity formulations of approximately 500 cps (or millipascal seconds) at 80 degrees Centigrade are preferred.

The liquid polymer should desirably remain at such viscosity (have a ‘pot life’) for sufficiently long to allow effective filling of the cavity 700. A pot-life of at least 5 minutes greater than the fill time is preferred (for example between about 7 and 15 minutes, and in an embodiment between about 8 and 13 minutes).

The liquid polymer should desirably solidify sufficiently quickly that the casting mould apparatus 300 can be used to manufacture many spiral trough elements in relatively quick succession. However, solidification that is too rapid may adversely affect bonding of the wear liner 240 to the structural component 210. A solidification time of between about 45 minutes and two hours is considered to provide adequately high productivity of the casting mould apparatus 300 while providing adequate bonding of the wear liner 240 to the structural component 210 (which, without wishing to be bound by theory, is believed to be achieved by effective polymer chain cross linking of the solidifying polymer to the primer). Heating of the casting mould part 302, as described above, can substantially assist in reducing the time required for solidification of liquid polyurethane.

The liquid polymer should also be such as to provide wear performance comparable to or better than high performance spray systems currently employed in the industry, as previously described. In the case of a liquid polymer comprising polyurethane, this is considered relatively straightforward to achieve, as the formulation and application of sprayed polyurethane is considered to substantially compromise wear performance compared to use of liquid polyurethane poured into a mould or cavity and allowed to solidify moulded

It is considered to be a matter of routine for a person skilled in the relevant art to ascertain a liquid polymer comprising polyurethane which satisfies the above criteria, As foreshadowed above, the dimensional accuracy of the wear surface 242 of the wear liner 240 is important for separation performance. Thus the dimensional accuracy and durability of the casting mould part 302, and especially the casting mould surface 306 is important.

In an embodiment the casting mould part 302 is made from a metal, such as for example aluminium alloy. The metal is preferably cast, and at least the casting mould surface 306 is machined to the desired shape to high accuracy, preferably by CNC machining. In an embodiment surfaces of the casting mould part 302 which contact the structural component 210 are also machined, preferably by CNC machining, to high accuracy. The casting mould surface 306, and optionally, in embodiments, surfaces of the casting mould part 302 which contact the structural component 210, may be machined to an accuracy of plus/minus 0.5mm.

In an embodiment the casting mould part 302 comprises a number of separately manufactured segments, each made to high accuracy as described above, as illustrated schematically in Figure 12.

In the embodiment of Figure 12, the casting mould part 302 comprises first to seventh casting mould segments, 1201 to 1207. Each of the casting mould segments, 1201 to 1207 is, in use, connected to at least one of the other casting mould segments, 1201 to 1207, and each is connected to the central post 304.

Figures 13 and 14 illustrate only the first and second of the casting mould segments, 1201, 1202, by way of example.

In the illustrated embodiment of Figure 12 each of the casting mould segments 1201 to 1207 comprises half a spiral turn so that the seven casting mould segments 1201 to 1207 together provide a casting mould part comprising 3.5 spiral turns. Of course, in alternative embodiments more or fewer casting mould segments may be used, the casting mould segments may each comprise more or less than half a spiral turn (and each need not comprise the same degree of spiral turn as each or any of the others) and may total greater than or less than 3.5 spiral turns, depending on requirements.

The first to seventh casting mould segments 1201 to 1207 each comprises a respective part- spiral casting mould surface part 1211 to 1217.

At least some of the shapes of the casting mould surface parts 1211 to 1217 may be different from each other in order to provide a spiral trough element in which the wear surface, which is the separation surface of a spiral separator, is different in different turns of the trough, as is known in the art. For example, the shapes of the casting mould surface parts 1211 to 1217 may differ in order to provide a wear surface, or separation surface, of a spiral trough element which differs in cross-trough floor angle.

That is a main surface part, which may correspond to the trough floor mould surface part 610, of a one part-spiral casting mould surface part, for example 1211, of one of the casting mould segments, for example 1201 , may be oriented at a first angle relative to a central axis of the generally spiral casting mould surface, and a main surface part, which may correspond to the trough floor mould surface part 610, of another part-spiral casting mould surface part, for example, 1212 of another of the casting mould segments, for example 1201, may be oriented at a second, different angle relative to the central axis of the generally spiral casting mould surface.

Any number of the part-spiral casting mould surface parts 1211 to 1217 may differ from others of the part-spiral casting mould surface parts 1211 to 1217 in this manner.

Of course, in an embodiment in which the casting mould surface (e.g. 306) is provided by a single unitary part, the shape, or angle, of the one or more parts of the casting mould surface may differ between (or within) different spiral turns of the casting mould surface.

In the embodiment of Figure 12 each of the casting mould segments 1201 to 1207 are illustrated as comprising a first end attachment part e.g. 1220, and a second end attachment part, e.g 1230, for facilitating attachment to other casting mould segments. In the illustrated embodiment the attachment parts 1220, 1230, comprise upstanding walls or flanges, each provided with apertures, e.g. 1221, 1222, 1223, 1224, for receiving fasteners such as bolts, or dowels to assist alignment. For example, the apertures 1221 and 1224, as illustrated, are adapted to receive dowels 1402, and the apertures 1222 and 1223 are adapted to receive fasteners such as bolts 1404.

Each of the casting mould segments 1201 to 1207 further comprises a side attachment part, e.g. 1230, which in the illustrated embodiment comprises a radially inner upstanding wall or flange, provided with fixing apertures 1232, 1234, for receiving fasteners such as bolts, for attaching the mould segment to the central post 304.

Each of the casting mould segments 1201 to 1207 further comprises a central recess, e.g. 1240, which may be used to accommodate a heating element.

Figures 15 to 17 correspond somewhat to Figures 3 to 5, but illustrate an alternative embodiment generally designated 15300, which differs from the casting mould apparatus 300, of Figures 3 to 5, in that the casting mould apparatus 15300 provides powered rotation of a central post 15304 (corresponding generally to central post 304 of Figures 3 to 5), and thus of the casting mould part 15302 (corresponding generally to the casting mould part 302 of Figures 3 to 5) and of the generally spiral casting mould surface 15306 (corresponding generally to generally spiral casting mould surface 306 of Figures 3 to 5).

The casting mould apparatus 15300 comprises a rotation arrangement 15301 comprising a motor 15370 operable, via a control box 15372, for example by a foot operated switch 15374, which can be operated to rotate the central post 15304, the casting mould part 15302 and the casting mould surface 15306, about the helical axis of the casting mould part 15302 (corresponding to the axis of the central post 15304), in either rotational direction. As foreshadowed above, the central post 15304 is rotatably mounted in a through hole 15314 (corresponding generally to through hole 314) using appropriate bearings 15315 in the through hole 15314.

Powered rotation of the central post 15304 and the casting mould part 15302 can facilitate several tasks that are performed in embodiments of the manufacturing methods of the present disclosure.

For example, powered rotation of the central post 15304 and the casting mould part 15302 can facilitate the threading of the structural component 210 onto the casting mould apparatus 15300, by removing the need to rotate the structural component 210. Rather the central post 15304 and generally spiral casting mould surface 15306 are selectively rotated by an operator (for example using the foot operated switch 15374 to operate the motor 15370), as illustrated by arrow 15380. Selection of suitable direction and speed of rotation can result in the structural component 210 requiring only axial movement, as indicated by the arrow 15382, in order to effect threading of the structural component 210 onto the casting mould apparatus 15300. Correspondingly, unthreading of the structural component 210 (and wear liner 240) from the casting mould apparatus 15300 can be facilitated by rotation of the central post 15304 and the casting mould part 15302 in the opposite direction.

Powered rotation of the central post 15304 and the casting mould part 15302 can also facilitate other tasks such as application of release agent to the casting mould surface 15306, prising apart a completed spiral trough element from the casting mould surface 15306, and applying or removing clamps 800.

Further, the rotation arrangement 15301 may include one or more preset operations (which may be selectable by a user via a user interface) which can be automatically performed by the rotation arrangement 15301 , for example in response to a user selection. Each of the preset operations may comprise one or more of a predetermined direction of rotation, a predetermined speed of rotation, a predetermined degree of rotation and/or a predetermined final rotational position. Thus for example: a first preset control may be provided to automatically rotate the casting mould part 15302 in a direction and at a speed suitable for threading a structural component 210 onto the casting mould part 15302, and/or by a suitable amount of rotation displacement (for example, approximately the same number of rotations as the number of spiral turns of the structural component); a second preset control may be provided to automatically rotate the casting mould part 15302 in a direction and at a speed suitable for applying clamps 800, and/or in preset increments suitable for applying clamps 800 (such as the desired angular displacement between clamps); a third preset control may be provided for rotating the casting mould part 15302 to a ‘pouring position’ in which the fill spout arrangements 404 of a structural component 210 clamped to the casting mould part 15302 are located at the tops of respective spiral turns of the structural component 210; a fourth preset control may be provided to automatically rotate the casting mould part 15302 in a direction and at a speed suitable for removing clamps 800, and/or in preset increments suitable for removing clamps 800; a fifth preset control may be provided to automatically rotate the casting mould part 15302 in a direction and at a speed suitable for prising apart a completed spiral trough element from the casting mould surface 15306; a sixth preset control may be provided to automatically rotate the casting mould part 15302 in a direction and at a speed suitable for unthreading a completed spiral trough element from the casting mould part 15302, and/or by a suitable amount of rotation displacement (for example, approximately the same number of rotations as the number of spiral turns of the structural component); and a sixth preset control may be provided to automatically rotate the casting mould part 15302 in a direction and speed suitable for applying release agent to the casting mould surface 15306.

Any one or more of these, or other, preset controls may be provided.

In a further alternative embodiment (not shown) the structural component 210 may be fixed in position (i.e. substantially stationary) during intertwining, and the casting mould part 15302 may be moved both rotationally and axially to effect intertwining, for example by providing the support structure 15308 (and/or the central post 15304) with an arrangement for movement in the axial direction of the central post 15304: for example, the support structure 15308 could be provided on a suitable rail arrangement (not shown) rather than fixedly attached to a floor.

Figure 18 corresponds generally to Figure 4, but includes illustration of a first-end flange 1802 and a second-end flange 1804 the structural component 210.

At least embodiments according to the present disclosure provide significant working advantages over at least some prior art approaches.

Avoiding spraying of polyurethane is considered to provide some particular advantages.

Spray urethane is formulated to provide a very fast ‘tack’ time to prevent runoff from the surface as it is applied. This limits the material wear performance of wear liners formed by spray systems compared to pouring liquid urethane into a cavity and allowing it to solidify. Further, the spray mode of application of these spray urethane formulations can entrain air in the deposited layer leading to poor polymer chain cross linking and poor wear performance. In a sliding wear environment, it is not uncommon for high quality cast urethane materials to outperform the best spray system by an order of magnitude or more.

An advantage of providing a wear liner with enhanced wear characteristics is increased wear liner life, and hence increased trough life. In some conditions, for example where mineral slurries include iron ore and/or any sharp or crushed minerals or where particle sizes above 1 mm are common, the wear life of the current spray lined spiral separator troughs in spiral separators can be as short as three years.

A further advantage of providing a wear liner with enhanced wear characteristics is that the wear surface is less subject to change over time. Changes in the wear surface can result in deterioration of the spiral profile over time, which adversely affects separator performance.

Accordingly, provision of a wear liner which is more resistant to changes in the wear surface appears advantageous over increasing the thickness of a less wear-resistant liner in an attempt to prolong trough life.

Other limitations of use of sprayed polyurethane compared to liquid polyurethane cast in a cavity include: environmental concerns due to the airborne emissions of the spray process; substantially higher cost per kilogram compared to similar high performance casting elastomeric polyurethanes, typically around 30 to 50% more kilogram; lower application efficiency having significantly higher losses due to overspray and airborne emissions.

Further, reverse moulding methods currently employed require that the high accuracy moulds that form the critical spiral wear surface shape be sprayed to form a polyurethane layer, and that fibreglass be laminated onto the sprayed layer, while the sprayed layer remains on the mould surface. This typically requires the high accuracy mould be engaged for about a full day as the fibreglass laminate is formed and cured to a barcol hardness allowing mould stripping the following day. Production therefor, is, more or less, limited to one product per mould per day. In contrast the high accuracy moulds in embodiments in accordance with the present disclosure can be used to manufacture a spiral trough element in approximately one to two hours.

Further, in the reverse moulding methods currently employed because the fibreglass structural element is formed over the sprayed polyurethane layer, the forming of the fibreglass structural element must be performed at the location of the high accuracy mould. Thus the entire manufacturing process of the reverse moulded spiral trough must, in practical terms, be performed in a single location. This limits the ability to subcontract or utilise external suppliers for any or, each, part of the process. In contrast, in embodiments in accordance with the present disclosure, the structural component may be manufactured at a location remote from the casting mould apparatus and transported to the location of the casting mould apparatus from its place of manufacture. This facilitates subcontracting manufacture of the structural component and use of external suppliers, while maintaining the manufacture of the wear liner, for which accuracy is particularly important, in-house.

Spiral troughs constructed from separately manufactured injection moulded segments require significant assembly time after manufacture of the segments in order to piece together many segments into a multiple turn spiral.

Further, it is believed that normal injection moulding is unsuitable for producing continuous multiple turn spirals as ejection of the part appears impossible, or at best impracticable not least due to the very high cost that would be involved in manufacture of a suitable mould.

It should be appreciated that the word ‘spiral’, as used herein, should be taken to have a meaning consistent with its meaning when used in the field of wet gravity separation to describe ‘spiral’ troughs of gravity separators and ‘spiral’ wear surfaces of such troughs, rather than a strict geometrical or mathematical meaning.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features.

It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.