Improvements to spiral separators and apparatus therefor

Abstract

Apparatus for use between upstream and downstream stages of spiral separator comprises: a splitting arrangement for splitting the slurry flow into a concentrate part, and a remainder with a lower concentration of dense mineral; and a mixing arrangement for mixing a fluid more outward part of the remainder with a less fluid radially more inward part of the slurry, to provide a mixed remainder part for feeding onto the downstream spiral trough part. The mixing arrangement comprises a deflector for deflecting at least some of the more fluid part of the slurry upwardly towards an upper baffle part, and the upper baffle part is configured to disperse the upwardly deflected part of the remainder to allow mixing with the less fluid part of the remainder and provide reduced velocity of the more fluid part prior to feeding onto the downstream spiral trough part.

Description

[0001] IMPROVEMENTS TO SPIRAL SEPARATORS AND APPARATUS THEREFOR

[0002] FIELD

[0003] The present disclosure relates to spiral separators and especially, but not exclusively to a spiral separators for separating heavy mineral sands from gangue in a mineral slurry. The disclosure extends to parts or components of spiral separators, and to related methods.

[0004] BACKGROUND

[0005] Spiral separators are extensively used for the wet gravity separation of particulate solids according to their specific gravity.

[0006] A known type of spiral separator comprises one or more helical sluices, often referred to as spirals or spiral troughs, mounted on a central column which is vertical in use. Spiral separators with two or more intertwined helical troughs are known as double- or multiple-start separators. A feed arrangement is provided for feeding a mineral / water slurry to the uppermost part of the, or each, spiral trough. The slurry is induced, by gravity, to flow down the spiral. The particulates in the slurry are subject to a number of different forces, including gravitational force, drag forces due to contact with the spiral, and centrifugal force due to movement along a generally helical path. Broadly speaking, particles with higher specific gravity move toward the radially inner part of the spiral, and particles with lower specific gravity (lower density) move towards the outer parts of the spiral. Suitably distributed off-take openings or channels collect streams of particulates which have undergone this separation.

[0007] Two-stage spiral separators provide a more upstream spiral trough part for performing a first stage of separation and a more downstream spiral trough part. An off-take opening or channel is provided at the bottom of the more upstream spiral trough part, via which a part of the mineral slurry in which a more dense, mineral has been concentrated (by separation occurring in the more upstream spiral trough part) is removed from the remainder of the slurry. The remainder of the slurry continues to the more downstream spiral trough part, in which further separation occurs. In the more downstream trough part more dense mineral distributed in the remainder of the slurry is separated, or concentrated, for example, in a radially inner region of the downstream trough part. An off-take opening or channel is provided at the bottom of the more downstream spiral trough part to separate the concentrated mineral from the remainder of the slurry.

[0008] Third, and possibly one or more subsequent stages may be provided to further separate minerals of different densities.

[0009] An issue with two-stage spiral separators is that by the bottom of the upstream trough part (or first stage) much of the water of the slurry has migrated to the radially outer region of the trough, leaving material in a central region the trough ‘dewatered’, and with low fluidity. Thus, a slow moving central ‘slug’ of material, consisting largely of lower density mineral, but with some higher density mineral entrained therein, may be formed. If the slurry flows onto the downstream trough part (or second stage) in this form, separation of the more mineral from the rest of the slurry is inhibited, and separation effectiveness on the downstream trough part is poor.

[0010] Steps may therefore be taken to fluidise the central region of the slurry. One approach has been to use a Tepulper’ to add water and thereby Tefluidise’ the central slug of material, for example, by deflecting water from the radially outer region of the spiral trough into the central slug of material.

[0011] The present applicant’s earlier patent application, PCT / AU2019 / 051413 (Publication No. W02020163893), the entire disclosure of which is hereby incorporated by reference, discloses an approach in which the slurry to be fed onto the more downstream trough part or stage for further separation is thoroughly mixed by a slurry preparation arrangement, and in which the resultant mixed slurry is fed onto the downstream trough part. It will be appreciated that the slurry to be fed onto the more downstream trough part or stage for further separation does not include a concentrate part of the slurry, containing a high concentration of dense mineral, which has been taken of at or close to the bottom of the more upstream trough part. Further, the kinetic energy of the fast-moving, radially outer, fluid component is intentionally reduced, so that the mixed slurry is fed onto the downstream trough part in a manner similar to that in which slurry is fed by the feed arrangement onto the upstream trough part. This approach may provide improved separation on the downstream trough part compared to merely allowing the slurry (minus the taken off concentrate part) to progress to the downstream trough part without mixing.

[0012] The present applicant’s subsequent patent application, PCT / AU2021 / 050900 (Publication No. WO2022036391 ), the entire disclosure of which is hereby incorporated by reference, discloses (inter alia) an improvement to the approach disclosed in PCT / AU2019 / 051413. In summary, rather than mixing all of the slurry from the upstream trough part which is to be fed onto the downstream trough part (or second or subsequent stage) for further separation, PCT / AU2021 / 050900 teaches that a semi-concentrate or ‘near miss’ part of the slurry, in which the more dense mineral is somewhat concentrated, but less concentrated than in the taken off concentrate part of the slurry, bypasses the mixing and is fed onto a radially inward part of the downstream trough part.

[0013] This approach is considered to provide improved separation compared to the apparatus of PCT / AU2019 / 051413, at least under some circumstances, by allowing separation on the more downstream trough part to utilise at least some of the separation performed by the more upstream trough part.

[0014] However, it has been ascertained that there is scope to provide improvements to the spiral separators disclosed in PCT / AU2019 / 051413 and / or PCT / AU2021 / 050900, and / or to at least provide one or more useful variations. However, it will be appreciated that application of the disclosure herein is not limited to the spiral separators disclosed in PCT / AU2019 / 051413 and / or PCT / AU2021 / 050900, but may be applicable to other spiral separators.

[0015] 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.

[0016] SUMMARY

[0017] According to a first aspect of the present disclosure there is provided a spiral separator for separating more dense mineral from less dense mineral, the spiral separator having a splitting and mixing part operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the splitting arrangement comprises a first splitter for splitting the first concentrate part from the second concentrate part, and a second splitter for splitting the remainder part from the second concentrate part, and wherein the first splitter is positioned downstream of the second splitter.

[0018] In an embodiment the splitting and mixing part further comprises a bypass channel for conveying the second concentrate part towards the downstream spiral trough part, for further separation of more dense from less dense mineral, such that the semi-concentrate component bypasses and is segregated from the mixing arrangement.

[0019] According to a further aspect of the present disclosure there is provided an apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising a splitting and mixing part for provision operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the splitting arrangement comprises a first splitter for splitting the first concentrate part from the second concentrate part, and a second splitter for splitting the remainder part from the second concentrate part, and wherein the first splitter is positioned downstream of the second splitter.

[0020] Features set out in relation to embodiments of the first aspect may be incorporated mutatis mutandis in this further aspect.

[0021] According to a second aspect of the present disclosure there is provided a spiral separator for separating more dense mineral from less dense mineral, the spiral separator having a splitting and mixing part operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part via a mixing arrangement outlet; wherein the splitting and mixing arrangement has an angular extent, between the most upstream part of the splitting arrangement and the mixing arrangement outlet, of no more than 75 degrees of a spiral turn of the spiral separator. In an embodiment the splitting and mixing arrangement has an angular extent, between the most upstream part of the splitting arrangement and the mixing arrangement outlet, of no more than 60 degrees of a spiral turn of the spiral separator.

[0022] In an embodiment the splitting and mixing arrangement has an angular extent, between the most upstream part of the splitting arrangement and the mixing arrangement outlet, of no more than 50 degrees of a spiral turn of the spiral separator.

[0023] In an embodiment the splitting and mixing part further comprises a bypass channel for conveying the second concentrate part towards the downstream spiral trough part, for further separation of more dense from less dense mineral, such that the semi-concentrate component bypasses and is segregated from the mixing arrangement.

[0024] According to a further aspect of the present disclosure there is provided an apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising a splitting and mixing part for provision operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part via a mixing arrangement outlet; wherein the splitting and mixing part has an angular extent, between the most upstream part of the splitting arrangement and the mixing arrangement outlet, of no more than 75 degrees of a spiral turn of the spiral separator. Features set out in relation to embodiments of the second aspect may be incorporated mutatis mutandis in this further aspect.

[0025] According to a third aspect of the present disclosure there is provided a spiral separator for separating more dense mineral from less dense mineral, the spiral separator having a splitting and mixing part operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into a concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the mixing arrangement comprises a deflector for deflecting at least some of the more fluid radially more outward part of the remainder part upwardly towards an upper baffle part which extends over and is spaced apart from a floor part of the mixing arrangement, and wherein the upper baffle part is configured to disperse the upwardly deflected part of the remainder part to thereby allow mixing with the less fluid radially more inward part of the remainder part, and provide reduced velocity of the more fluid radially more outward part of the remainder part prior to feeding onto the downstream spiral trough part.

[0026] In an embodiment the mixing arrangement comprises a plurality of baffle parts which extend in the direction between the upper baffle part and a floor of the mixing arrangement.

[0027] In an embodiment at least some of the baffle parts of the pluralirt of baffle parts extend at least approximately half the distance between the upper baffle part and a floor of the mixing arrangement. In an embodiment the mixing arrangement comprises a plurality of discrete baffle parts.

[0028] In an embodiment the mixing arrangement comprises a plurality of discrete spaced apart baffle parts.

[0029] In an embodiment the plurality of baffle parts is configured so that there is no line of sight between the deflector and a slurry exit opening of the mixing part.

[0030] In an embodiment the plurality of baffle parts is configured to impede flow of deflected slurry part between the deflector and an exit opening of the mixing part.

[0031] In an embodiment the plurality of baffle parts comprises at least seven discrete baffle parts.

[0032] In an embodiment the plurality of baffle parts comprises at least ten discrete baffle parts.

[0033] In an embodiment the plurality of baffle parts comprises at least fifteen discrete baffle parts.

[0034] In an embodiment the plurality of baffle parts is configured in a plurality of rows.

[0035] In an embodiment the plurality of baffle parts is configured in at least three rows, each row comprising at least three baffle parts.

[0036] In an embodiment at least one row of baffle parts is staggered of offset with respect to at least one other row of baffle parts.

[0037] In an embodiment the plurality of baffle parts are arranged in at least three rows.

[0038] In an embodiment the

[0039] In an embodiment the upper baffle part is configured with a number of projections having surfaces oriented to disperse at least some of the deflected part of the remainder part in directions other that the slurry flow direction of the spiral separator.

[0040] In an embodiment said baffle parts comprise said projections. In an embodiment the projections extend substantially downwardly from a surface of the upper baffle.

[0041] In an embodiment the mixing arrangement comprises a guide for guiding small particles of dense material entrained in the radially outer high velocity, more fluid part of the slurry flow, but contacting or close to the trough floor, radially inwardly as they progress in the downstream direction at or close to the mixing arrangement.

[0042] In an embodiment the mixing arrangement comprises a guide for guiding small particles of dense material from a radially more outwards position to a radially more inwards position as they progress in the downstream direction at or close to the mixing arrangement.

[0043] In an embodiment the guide is provided at or adjacent a floor part of the missing arrangement.

[0044] In an embodiment the guide is provided at least partially by the deflector.

[0045] In an embodiment the floor of the mixing arrangement is configured to provide a surface along which the less fluid part of the remainder part progresses towards an outlet of the mixing arrangement.

[0046] In an embodiment the floor of the mixing arrangement is configured to provide a surface upon which the less fluid part of the remainder mixes with the more fluid part of the remainder part.

[0047] In an embodiment the upper baffle comprises a roof of the mixing arrangement.

[0048] In an embodiment at least some of the projections provide a deflection surface facing generally in the upstream direction.

[0049] In an embodiment at least some of the projections provide a deflection surface facing generally in the upstream direction.

[0050] In an embodiment at least some of the deflection surfaces are concave.

[0051] In an embodiment at least some of the deflection surfaces are generally cylindrical or part-cylindrical, or wholly or partly frustoconical. In an embodiment the splitting arrangement is configured to split the concentrate part into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and the second concentrate part having a higher concentration of dense mineral than the remainder part.

[0052] According to a further aspect of the present disclosure there is provided an apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising a splitting and mixing part for provision operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into a concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the mixing arrangement comprises a deflector for deflecting at least some of the more fluid radially more outward part of the remainder part upwardly towards an upper baffle part which extends over and is spaced apart from a floor part of the mixing arrangement, and wherein the upper baffle part is configured to disperse the upwardly deflected part of the remainder part to thereby allow mixing with the less fluid radially more inward part of the remainder part, and provide reduced velocity of the more fluid radially more outward part of the remainder part prior to feeding onto the downstream spiral trough part.

[0053] Features set out in relation to embodiments of the third aspect may be incorporated mutatis mutandis in this further aspect.

[0054] According to a fourth aspect of the present disclosure there is provided a spiral separator for separating more dense mineral from less dense mineral in a mineral slurry, the spiral separator having at least two substantially parallel and intertwined spiral troughs; wherein each spiral trough has an adjustable splitter for splitting at least part of the mineral slurry flow into a first and second parts, the first part having a higher concentration of more dense mineral than the second part, wherein at least two of the adjustable splitters of at least two respective spiral troughs are mechanically connected so that a single adjustment operation adjusts said at least two adjustable splitters so that the adjustment of each of the at least two adjustable splitters substantially corresponds.

[0055] In an embodiment the adjustable splitters each comprise a pivotable member, such that pivoting movement of the pivotable member about an axis.

[0056] In an embodiment the adjustable splitters are arranged so that the axes thereof are vertically aligned.

[0057] In an embodiment the pivotable members of respective adjustable splitters are connected by a shaft, so that rotation of the shaft adjusts each pivotable member.

[0058] In an embodiment each adjustable splitter is a splitter of a splitting arrangement of one or more of the first to third aspects.

[0059] According to a fifth aspect of the present disclosure there is provided an apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising: a mixing arrangement for mixing a more fluid radially more outward part of a slurry from an upstream part of the spiral separator with a less fluid radially more inward part of the slurry from the upstream part, to provide a mixed slurry onto a more downstream spiral trough part; wherein the mixing arrangement comprises a deflector for deflecting at least some of the more fluid radially more outward part of the slurry upwardly towards an upper baffle part which extends over and is spaced apart from a floor part of the mixing arrangement, and wherein the upper baffle part is configured to disperse the upwardly deflected part of the slurry to thereby allow mixing with the less fluid radially more inward part of the slurry, and provide reduced velocity of the more fluid radially more outward part of the slurry prior to feeding onto the more downstream spiral trough part.

[0060] It will be appreciated that features of any of the above aspects, or embodiments thereof may be incorporated into any of the other aspects.

[0061] BRIEF DESCRIPTION OF THE DRAWINGS

[0062] 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:

[0063] Figure 1 is a schematic plan view of a part of an embodiment of a spiral separator in accordance with the present disclosure, showing a splitting and mixing part thereof;

[0064] Figure 2 is schematic a plan view corresponding to Figure 1 but with some parts omitted so that otherwise hidden detail can be seen;

[0065] Figure 3 is a schematic perspective view, from an upstream side, of the embodiment of Figure 1 ;

[0066] Figure 4 is a schematic perspective view showing the underside of the cover of the embodiment of Figures 1 and 3;

[0067] Figure 5 is a schematic perspective view, from a downstream side, of the embodiment of Figure 1 ;

[0068] Figure 6 is a schematic perspective view similar to that of Figure 5, but from a slightly different angle, and showing less of the separator;

[0069] Figure 7 is a schematic front elevation of a three-start, two stage, spiral separator including three splitting and mixing parts, each similar to that of Figures 1 to 6, associated with the three respective spiral troughs of the spiral separator;

[0070] Figure 8 a schematic perspective view, from a downstream side, of part of a three- start separator, for example, the spiral separator of Figure 7, showing three splitting and mixing parts, each similar to that of Figures 1 to 6, associated with the three respective troughs thereof;

[0071] Figure 9 is a schematic plan view of a part of an embodiment of a spiral separator in accordance with the present disclosure, illustrating a alternative embodiment of a splitting and mixing part;

[0072] Figure 10 is a schematic plan view showing an embodiment of a splitting and mixing part which is an alternative to the splitting and mixing part of a spiral separator of Figures 1 to 6;

[0073] Figure 11 is a schematic perspective view, from an upstream side, of the embodiment of Figure 10;

[0074] Figure 12 is a schematic perspective view, from a downstream side, of the embodiment of Figure 10;

[0075] Figure 13 is a schematic perspective view, showing the underside of the cover of the embodiment of Figure 10, from an upstream side;

[0076] Figure 14 is a schematic perspective view, showing the underside of the cover of the embodiment of Figure 10, from a radially outer side; and

[0077] Figure 15 is a schematic bottom plan view, showing the underside of the cover of the embodiment of Figure 10.

[0078] DETAILED DESCRIPTION

[0079] Figures 1 to 6 illustrate part of a spiral separator including a splitting and mixing part generally designated by the reference numeral 10.

[0080] The present applicant’s earlier patent application, PCT / AU2021 / 050900, discloses an approach to providing slurry onto a downstream trough part (or second or subsequent stage) of a spiral separator, after some denser mineral has been separated out as a concentrate subsequent to separation occurring on an upstream trough part. PCT / AU2021 / 050900 that a semi-concentrate or ‘near miss’ part of the slurry, in which the more dense mineral is somewhat concentrated, but less concentrated than in the taken off concentrate part of the slurry, bypasses the mixing and is fed onto a radially inward part of the downstream trough part. The splitting and mixing part 10 adheres to the same approach, but provides some changes to enhance utility.

[0081] The splitting and mixing part 10 is, in use, provided operatively intermediate an upstream stage spiral trough part 1 and a downstream stage spiral trough part 2 of a spiral separator. The splitting and mixing part 10 receives slurry which has undergone radial separation, as briefly described in the background section, and feeds slurry that requires further separation onto the downstream stage spiral trough part 2. The splitting and mixing part 10 comprises a splitting arrangement 11 , comprising first and second splitters 23, 33 and a mixing arrangement 12, which will be described in due course.

[0082] As an overview, the first splitter 23 located at a radially inner part of the splitting and mixing part 10, splits a part of the slurry flow which includes a high proportion / concentration of dense mineral into a first (more radially inner) concentrate part suitable for offtake as concentrate and a second (less radially inner) concentrate part, which has a significant but lower proportion / concentration of dense mineral, and which may be regarded as semi-concentrate, ‘high grade mids’ or ‘near miss”, narrowly missing the concentrate grade. The second concentrate part is to undergo further separation on the downstream stage spiral trough part 2. A second splitter 33 located more radially outwards than the first splitter, splits a remainder part of the slurry from the second concentrate part. The remainder part of the slurry typically comprises a fast moving, highly fluid radially outer part of the slurry and a dewatered, slow moving radially intermediate part. The remainder part is fed to the mixing arrangement 12 which mixes the fluid and dewatered parts of the slurry, refluidising the dewatered part and reduces the kinetic energy of the highly fluid part. The mixed slurry is fed onto the downstream stage spiral trough part 2. The second concentrate part bypasses the mixing arrangement, and is fed onto the downstream stage spiral trough part 2 radially inwardly of the mixed remainder part of the slurry.

[0083] The apparatus illustrated in Figures 1 to 6 will now be described in more detail.

[0084] The splitting and mixing part 10 provides a slurry entry region 13 at an upstream part thereof for entry of slurry exiting the upstream stage trough part 1 of the spiral separator. The slurry entry region 13 provides a trough floor part 14, which in the illustrated embodiment is an integral part floor of a spiral of the spiral separator, as in this embodiment the splitting and mixing part 10 built into, and / or onto the spiral. However, it will be appreciated that if desired a variation of the splitting and mixing part may be provided as a modular unit, configured to be attached between discrete upstream and downstream stage spiral trough parts, in which case the trough floor part 14 should be configured to be substantially continuous with the trough floor of the upstream trough part, so that slurry can flow substantially unimpeded from the upstream trough part onto the splitting and mixing part 10.

[0085] The splitting and mixing part 10 provides an upstanding, radially outer, wall 16, which in use is generally continuous with upstanding outer wall(s) of the upstream and downstream stage spiral trough parts, and in this embodiment is integral therewith.

[0086] The splitting and mixing part 10 further provides an upstanding, radially inner, wall 18, which in use is generally continuous with, and in this embodiment integral with, upstanding inner wall(s) of the upstream and downstream stage spiral trough parts.

[0087] The splitting and mixing part 10 provides a radially inner region 22 of the trough floor part 14. The radially inner region 22 receives parts of the slurry flow which have a relatively high concentration of more dense mineral, due to separation on the upstream stage trough part 1 . Provided on or in the radially inner region 22 is the first splitter 23, for splitting the first (more radially inner) concentrate part from the second (less radially inner) concentrate part.

[0088] The first splitter 23 may be a rotatable vane adjustable splitter as illustrated. The rotatable vane splitter may comprise vane 104 mounted on a shaft 105 such that the vane is rotationally fixed relative to the shaft. The shaft may be mounted to a main body of the splitting and mixing part 10, which in the illustrated embodiment is part of a spiral trough which also provides the upstream and downstream stage spiral trough parts 1 , 2. Manual rotation of the vane or shaft (or a handle or toolengaging part attached thereto) allows rotation / orientation of the vane to provide a blade-like upstream edge of the vane at the radial location where it is desired to split the slurry. The vane and shaft can then be rotationally locked by tightening a nut or by use of some other appropriate locking mechanism.

[0089] A region of the splitting and mixing part 10 radially inward of the first splitter 23 and between the first splitter 23 and the radially inner wall 18 provides at least an entry part of a concentrate offtake channel 101 for offtake of the first (more radially inner) concentrate part. The offtake of the first concentrate part may be by any suitable arrangement, for example: by piping the first concentrate part off the separator close to the mixing and splitting arrangement, by feeding the first concentrate part into a central post of the separator for collection further down the post; or by feeding the first concentrate part to a concentrate gutter of the downstream stage spiral trough part 2 so that it can flow to a collection outlet further down the separator but is segregated from the slurry being separated on the downstream stage spiral trough part 2. (These examples may be regarded as generally equivalent in principle, as in each example the first concentrate part is effectively separated from the rest of the slurry, does not undergo further spiral separation in the spiral separator, and is fed to a collection outlet.

[0090] A region of the splitting and mixing part 10 radially outward of the first splitter 23 and between the first splitter 23 and a radially inner wall 32 (to be described in due course) of the mixing arrangement 12 provides at least an entry part of a bypass channel 102 for feeding the second concentrate part to the downstream stage spiral trough part 2, so that the second concentrate part bypasses the mixing arrangement.

[0091] A radially intermediate region 24 of the trough floor 14, which is inclined downwardly in the downstream direction receives a high solid content, or middlings, part of the slurry flow, corresponding generally to a radially intermediate part of the slurry flow, from the upstream spiral trough part 1 . This high solid content, or middlings, part of the slurry flow may include most or all of a central, dewatered slug of material, as discussed in PCT / AU2021 / 050900.

[0092] A radially outer region 26 of the trough floor 14 receives a high velocity, high water content stream, corresponding generally to a high water content, most radially outward component of the slurry flow, from the upstream spiral trough part 1 . It will be appreciated that the high velocity water stream will also extend some way up the radially outer wall 16. The radially outer region 26 of the trough floor 14 transitions into a deflector 28, which in use directs the high velocity, more fluid part of the slurry flow water stream upwardly, so that it impacts a roof part 30 of the mixing arrangement 12. The deflector 28 is in the form of a ramp with a fluid guiding surface (which may be curved, for example, somewhat concave) with elevation sufficient to effectively project the high velocity, more fluid part of the slurry flow upwardly, so that it impacts the roof part 30. The deflector 28 also deflects the high velocity, more fluid part of the slurry flow slightly inwardly radially. The deflector may be made wholly or partially of a moulded or cast material, for example, polyurethane and may be attached to the trough by any suitable means, for example, by bonding (for example, using an epoxy bonding agent), by mechanical fasteners such as screws, and / or by provision of studs provided by the deflector 28 which are configured to be passes through apertures in the trough and fixed in place.

[0093] The radially intermediate region 24 of the trough floor 14 conveys the low-fluidity high solid content, or middlings, part of the slurry flow below the roof part 30 of the mixing arrangement 12. The radially intermediate region 24 of the trough floor 14 may be considered to provide a bottom wall of the mixing arrangement 12, at the part of the trough floor part 14 which the roof 30 overlies.

[0094] The mixing arrangement 12 may be regarded as comprising a mixing chamber, having an open upstream end and a partially open downstream end. The mixing arrangement has a radially outer wall, provided by the radially outer wall 16.

[0095] The mixing arrangement 12 also has a radially inner wall 32 which is positioned radially approximately between the radially inner floor region 22 and the radially intermediate floor region 24. The most upstream part of the radially inner wall 32 of the mixing arrangement 12 is provided with, or shaped to provide, the second splitter 33. This may be a fixed splitter, as illustrated, but could be an adjustable splitter if desired. (For example, a rotatable vane adjustable splitter, which may be similar to the first splitter 23 described above, may be provided at or close to the upstream end of the radially inner wall 32, and / or at or close to the illustrated position of the second splitter 33.) The mixing arrangement 12 further comprises the roof part 30. The roof part 30 provides projections 31 having surfaces oriented to disperse at least some of the deflected part of the remainder part in directions other than the slurry flow direction of the spiral separator. The projections 31 may therefore be considered to be baffles which reduce the downstream velocity of the deflected part of the remainder part.

[0096] In the illustrated embodiment the projections extend substantially downwardly from a surface of the roof, and each projection provides at least one deflection surface facing substantially in the upstream direction. More specifically, in the illustrated embodiment each deflection projection has a cross sectional shape substantially in the form of a crescent, with the concave surface thereof facing the upstream direction. Provision of concave deflection surfaces facing upstream (that is, so that the concave surfaces are impacted substantially perpendicularly by the flow of the high-fluid slurry part deflected by the deflector 28) has been found, at least in some circumstances, to provide substantial energy dissipation of the high-velocity highly- fluid component of the slurry, and allow effective mixing with the less fluid component of the slurry in the mixing arrangement. Of course, other shapes may be used.

[0097] It will be appreciated that the high velocity, more fluid part of the slurry flow from the upstream stage, after deflection by the deflector 28 and energy reduction by impact with the roof part 30 and projections 31 , drops onto the low-fluidity high solid content, or middlings, part of the slurry flow which is progressing along the radially intermediate region 24 of the trough floor 14 (bottom wall of the mixing arrangement 12), thus mixing, or remixing, these parts of the slurry flow to provide a low energy, mixed and rewatered remainder part of the slurry for feeding onto, and further separation by, the downstream stage of the separator.

[0098] The mixing arrangement 12 further comprises a downstream end wall 34. The downstream end wall 34 depends downwardly from a downstream end of the roof part 30, part of the way towards the floor part 14, leaving a gap between the downstream end wall 34 and the trough floor part 14, the gap forming an outlet 36 of the mixing arrangement 12, for egress of mixed and rewatered remainder part of the slurry onto a downstream spiral trough. The downstream end wall 34 and / or outlet 36 may further provide a deflector member, for example, in the form of a deflector vane 38 or deflection tube for deflecting wash water from part (for example, an uppermost, most-fluid, part) of the exiting slurry flow towards the semi-concentrate stream, in order to refluidise the second concentrate (semi-concentrate) stream as the second concentrate stream begins its passage along the downstream stage spiral trough part 2. Refluidising the second concentrate (semi-concentrate) stream may be useful as the second concentrate stream may have become somewhat dewatered during its flow near the radially inner part of the upstream stage spiral trough part 1 , and may facilitate mobility and, in particular, radial mobility of the particles in the slurry, which provides concentration of the more dense mineral in the downstream trough part 2. The wash water is preferably directed generally tangentially into the circular / helical flow of the second concentrate stream, to provide the desired increase in radial particle mobility without violently or unduly disrupting the flow of the second concentrate stream which could disperse the relatively high concentration of denser mineral across the width of the downstream stage spiral trough part 2.

[0099] In the illustrated embodiment the deflector vane 38 is substantially L-shaped in transverse cross section, having a substantially vertically oriented side plate 39 and a substantially horizontally oriented top plate 40. In the illustrated embodiment, the deflection vane 38 is rotationally adjustable to allow adjustment of the angle at which wash water is deflected onto the downstream stage spiral trough part 2. The described deflection vane 38 is believed to provide ample and reliable deflection, while avoiding undue upwards splashing and dispersion. In this context, ‘horizontal’ and ‘vertical’ should be regarded as including orientations substantially parallel and substantially perpendicular to the trough floor, respectively.

[0100] Rotational or angular adjustability of the deflection vane 38 may be provided by any suitable arrangement for mounting the deflection vane 38 at or near the outlet 39, for example, as illustrated, by attaching the deflector vane 38 to a mounting 41 provided on part of the mixing arrangement 12 (for example, the roof part 30 or the downstream end wall 34) by a bolt 42 which can be loosened to allow rotational adjustment of the deflector vane 38 and tightened to secure the deflection vane 38 in a desired rotational position. It will be appreciated that the mixing arrangement 12 provides a mixed, low velocity, low viscosity slurry, which flows though the outlet 36, to provide a mixed remainder slurry feed onto the downstream stage spiral trough part 2, for further spiral separation. It is believed that, as desired, the prepared mixed remainder slurry part flows into the second or subsequent stage in much the same well mixed and low velocity condition as is provided in conventional spiral separators by a feed box providing slurry to a first stage of a spiral separator.

[0101] It should be appreciated that in the illustrated embodiment the area between the deflecting surface of the deflector 28 and the trough is preferably solid material or blocked off by a blocking wall to prevent water from the high solid content flow migrating outwardly into this area, as such further dewatering of the already dewatered high solid content flow could further increase its viscosity sufficiently to undesirably impede flow, for example, causing sanding. Further, the bottom 29 of the deflector 28, where it connects to the trough floor, may form a guide which extends somewhat radially inwardly as it extends in the downstream direction. This can guide small particles of dense material entrained in the radially outer high velocity, more fluid part of the slurry flow, but contacting or close to the trough floor, radially inwardly for thorough mixing with the rest of the remainder part.

[0102] It should be appreciated that the various arrows or groups of arrows shown in Figure 1 are intended to schematically illustrate flow of the slurry from the downstream end of the upstream stage spiral trough part 1 , onto and through the splitting and mixing part 10, and onto the downstream stage spiral trough part 2, in use. Broadly: the arrow designated 110 indicates flow of the first concentrate part of the slurry from the downstream end of the upstream stage spiral trough part 1 , towards and onto the splitting and mixing part 10; the arrow designated 115 indicates flow of the second concentrate part of the slurry from the downstream end of the upstream stage spiral trough part 1 , towards and onto the splitting and mixing part 10, the arrow designated 120 indicates flow of a radially-central high-solids- content part of the slurry from the downstream end of the upstream stage spiral trough part 1 , towards and onto the splitting and mixing part 10; the arrow designated 125 indicates flow of a radially outer high-solids- content part of the slurry from the downstream end of the upstream stage spiral trough part 1 , towards and onto the splitting and mixing part 10; the arrows designated 130 indicate dispersion of the outer high-solids- content part of the slurry after deflection by the deflector 28 and impact with the roof part 30 and projections 31 ; the arrows designated 135 indicate the mixed, low energy slurry, prepared in the mixing arrangement by mixing and kinetic energy dissipation of the remainder part 12, flowing out of the outlet 36 and onto the downstream stage spiral trough part 2; the arrow designated 140 indicates the second concentrate part being fed from the bypass channel onto the downstream stage spiral trough part 2; and the arrow designated 145 indicates a wash water part of the relatively fluid, prepared low energy slurry deflected at the outlet 36 by deflector vane 38 directed tangentially towards the second concentrate part exiting from the bypass channel 102.

[0103] Figure 7 illustrates an embodiment of a three-start, two-stage spiral separator, generally designated by the reference numeral 701 , which each of the three spirals includes a splitting and mixing part 10, corresponding to that of Figures 1 to 6 between upstream and downstream stage spiral trough parts.

[0104] The spiral separator 701 , as illustrated in Figure 7, comprises an upright central post or column 703 supporting three spirals 705, 705A and 705B.

[0105] In the embodiment illustrated in Figure 7, the second and third spirals 705A, 705B are arranged so that each respective turn of each of the second and third spirals is substantially directly below the corresponding turn of the first spiral 705. As the three spirals of the separator 701 are substantially identical, for simplicity and clarity only the first spiral 705 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 be appreciated that the present disclosure is not limited to a spiral separator having three spirals, but is also applicable to spiral separators having a single spiral, two spirals, or four or more spirals, that is, generally, to singlestart and to multiple-start spiral separators. A conventional arrangement (not shown), for example, including a powered pump, is provided for admitting a slurry or pulp to each spiral via a feedbox, for example, feedbox 707, at a predetermined rate, at or adjacent the top of the separator. The feedbox 707 may be a conventional type of feedbox having stilling baffles (not shown) installed internally to slow and “still” the feed allowing low velocity entry of the slurry or pulp onto the first turn of the corresponding spiral. The terms “slurry” and “pulp”, as used herein, should be considered to be used interchangeably. Similarly, the terms “helix” and “spiral” should be considered to be used interchangeably, unless context dictates otherwise.

[0106] A splitting arrangement 709, which may be a conventional splitting arrangement, is provided at the bottom of each spiral 705, 705A, 705B for splitting the descending slurry stream of the lowest stage into fractions (for example, corresponding to radially distributed streams or bands) and off-take of the various fractions. In the illustrated embodiment the splitting arrangement 709 comprises splitters (not shown) and off-take channels 709A, 7097B, 709C provided to split and off-take the descending slurry flow into a concentrates fraction, a middlings fraction and a tails fraction, respectively. The separator 701 further includes a fourth off-take channel 709D for material from an off-take arrangement provided in the central column 703, which may be a higher grade concentrate.

[0107] The spiral separator 701 may be regarded as a two-stage separator, comprising a first stage 730 and a second stage 750.

[0108] The first stage 730 comprises a first helical trough part of each spiral, for example, a first, or upstream, helical trough part 700 of the first spiral 505. In the illustrated embodiment the first helical trough part 700 is about 3.5 turns from a pulp feed point 532, where pulp is fed onto the first helical trough part 700 by the feedbox 707 to a concentrate off-take point 734 provided at or adjacent the downstream end of the first helical trough 700, that is, substantially at the lower end of the first stage 730. The off-take point is associated with the splitting and mixing part, for example, splitting and mixing part 10, as described above, provided on each spiral between the first and second stages. The second stage 750 is directly downstream of the splitting and mixing part 10, and comprises a second helical trough part 700A which is about 3.5 turns from a pulp feed point where pulp exits the mixing region 740 and is fed onto the second helical trough 700A, to an off-take point at the splitting arrangement 709. The first and second helical trough parts 700, 700A of the first spiral 705 may be substantially identical, each providing a substantially similar trough shape and variation of floor angle over corresponding turns, for example, but not limited to trough shape and variation as described in PCT / AU2019 / 051413, although other types of trough, including troughs with a different number of turns, may of course be substituted if desired. If desired, one or more further similar stages may be provided, with each stage being separated by a mixing region.

[0109] It will be appreciated that as each respective turn of each of the second and third spirals 705A, 705B is substantially directly below the corresponding turn of the first spiral 705, the splitting and mixing parts 10 of the second and third spirals 705A, 705B, are directly below the splitting and mixing part 10 of the first spiral 705. Consequently, the first splitters 23 of each of the three splitting and mixing parts 10 are vertically aligned, and the shafts 104 of the first splitters 23 are co-axial. In the illustrated embodiment, the three shafts are replaced by a single shaft (or in an alternative the three shafts are connected so that they are rotationally locked together). The single shaft is schematically illustrated in Figure 7, and designated by the reference numeral 760. The vanes 103 of the splitters are rotationally locked to the shaft, and identically aligned. Thus, provision of a single shaft (or shafts rotationally locked together) and correspondingly aligned vanes for the three first splitters 23 results in a set of connected splitters, on different spirals of the spiral separator, connected so that a single adjustment operation adjusts all three adjustable splitters, and so that the adjustment of each adjustable splitters substantially corresponds.

[0110] It will be appreciated that a corresponding methodology can be used for rotational splitters on corresponding parts of different spirals of a spiral separator, irrespective of whether the rotational splitters are parts of a mixing and splitting arrangement, or whether they are splitters provided on a separator which does not include a “mixing arrangement”. Accordingly, this arrangement has general application to two- and multiple-start spiral separators.

[0111] Further, this disclosure has applicability to adjustable splitters other than rotating vane splitters, since adjustment parts of other types of splitter can also be mechanically connected to provide corresponding adjustment of all of the connected splitters in a single operation.

[0112] Figure 8 shows in more detail three vertically aligned splitting and mixing parts 10 on three respective spirals of a three start separator, with the orientation of the single shaft illustrated schematically by a thick black line, designated by the reference numeral 761 .

[0113] Figure 9 is a schematic plan view of an alternative splitting and mixing part 900 which may be very similar to the splitting and mixing part 10 of Figure 1 to 6, but which differs in that the first and second concentrate parts are both taken off as different grades of concentrate (rather than the second concentrate part being a treated as a “semi-concentrate” part which is fed onto the downstream stage for further separation. Accordingly, the splitting and mixing part 900 provides a first offtake channel 902 for offtake of the first concentrate part designated by arrows a 910, like the splitting and mixing part 10, but provides a second offtake channel 904 for offtake of the second concentrate part designated by arrows a 915, rather than providing a bypass channel for feeding the second concentrate part onto the working / separating surface of the second stage.

[0114] Figure 10 to 15 illustrate an embodiment of a splitting and mixing part 1010 which is an alternative to the splitting and mixing part 10 illustrated in Figures 1 to 6. The splitting and mixing part 1010 has many similarities to the splitting and mixing part 10, so that only the differences will be described in detail below. Features of the splitting and mixing part 1010 which are functionally similar to features of the splitting and mixing part 10 illustrated in Figures 1 to 6 are designated by corresponding reference numerals to avoid unnecessary repletion.

[0115] The main difference between the splitting and mixing part 1010 and the splitting and mixing part 10, is that projections 1031 of the splitting and mixing part 1010 differ from the projections 31 of the splitting and mixing part 10 in that they are designed and configured to avoid or minimise deflection (of the high velocity, more fluid part of the slurry flow from the upstream stage) by the projections 1031 in the upstream direction. It has been found that, at least in some circumstances, such deflection in the upstream direction can compromise slurry flow, for example, by causing beaching or stalling of the low-fluidity high solid content, or middlings, part of the slurry flow at the bottom of the upstream stage, which can adversely affect separation effectiveness.

[0116] In the illustrated embodiment, the projections 1031 are circular in cross section and are arranged on the roof part 30 to substantially occlude line-of sight between the deflector 28 and the outlet 36, to avoid unimpeded flow of the high velocity, more fluid part of the slurry flow from the upstream stage through the mixing arrangement.

[0117] The circular transverse cross sectional shape of the projections 1031 helps avoid or minimise deflection (of the high velocity, more fluid part of the slurry flow from the upstream stage) by the projections 1031 in the upstream direction, as foreshadowed above by avoiding providing any substantial surface of the projections 1031 perpendicular to the downstream direction. Alternative cross sectional shapes could be used if desired, for example, a triangular cross sectional shape with an apex pointing in the upstream direction, or in another variation the projections could be tapered-cylinder or frustoconical in shape.

[0118] The illustrated configuration of projections 1031 may be regarded as comprising a number of staggered or offset lines of projections.

[0119] The illustrated configuration of projections 1031 has been found to effectively dissipate energy (reduce velocity) of the high velocity, more fluid part of the slurry flow from the upstream stage deflected by deflector 28. The illustrated configuration of projections 1031 has (together with the other features of the disclosed embodiments) been found to provide a mixed and rewatered low velocity slurry at the outlet 36, which is desirably uniform in the radial direction across the opening and which is not unduly varied by variations in the parts of the slurry entering the mixing arrangement 1010. This can increase predictable feeding of the mixed rewatered slurry onto the downstream stage, which can in turn improve separation efficiency. The roof part 30 and projections 1031 may be cast as a single piece, for example, from polyurethane, although other manufacturing options are possible.

[0120] As shown in the drawings, the connection of the projections 1031 to the roof part 30 is smooth or radiused, rather than discontinuous. This can increase robustness of the connection and is also convenient for removal of cast roof parts from a mould.

[0121] In the illustrated embodiment, the projections extend from the roof and are smaller in length than the distance between the roof 30 and the trough floor to provide a region close to the trough floor which is free from projections. This can allow inadvertently included material in the slurry, such as fibrous material, to pass under the projections rather than becoming entangled, thus assisting in avoiding inadvertent blockages.

[0122] In an embodiment, at least some of the projections extend at least half of the distance between the roof and the trough floor.

[0123] In an embodiment, each of the projections is between 5mm and 20 mm in width (diameter, if cylindrical) and between about 15mm and 35 mm in length, although these dimensions should not be considered limiting. In a particular embodiment, each of the projections is approximately 7 to 13 mm in width (diameter, if cylindrical) and between about 20 mm and 30 mm in length.

[0124] In an alternative embodiment, the projections may extend fully between the roof and the floor. In such an embodiment, the projections may be of smaller transverse size close to the floor than they are close to the roof part (to mitigate the likelihood of blockages on or close to the floor, as discussed above).

[0125] It will be appreciated that the separation of more dense material from less dense material may be desirable for various reasons, for example, because the more dense material is valuable (for example, metal or metal ore) or because the more dense mineral is in effect an impurity (for example, treatment of silica sand). The present disclosure is considered to be of utility in both of these cases.

[0126] It will be appreciated that the disclosed embodiments provide working advantages. Providing the first splitter 23 downstream of the second splitter 33 (or at least not upstream of the second splitter 33) helps provide a compact structure. Providing the first splitter 23 downstream of the second splitter 33 also (in an embodiment with a bypass channel) reduces the required length of the bypass channel, reducing the likelihood of blockages.

[0127] It will be noted that the illustrated splitting and mixing parts 10, 900, 1010 have an angular extent of about 45 degrees, which is advantageously small. Generally speaking, spiral separators can be made to function better by increasing the number of turns over which separation occurs, but this incurs greater cost and requires more space in a mineral processing facility. For a separator with a given number of turns including any splitting and mixing parts, providing a splitting and mixing part with small angular extent increases the number of turns available for separation to be performed.

[0128] It will be appreciated that although the mixing arrangement has been described above in conjunction with a splitting arrangement, with the combination suitable for provision between stages of a spiral separator, it may also under certain circumstances be useful to ‘refresh’ the slurry flow by providing mixing of parts of the slurry flow (and especially more and less fluid parts of the slurry flow) at other positions on a spiral separator. For example, it may be useful to mix more and less fluid parts of the slurry flow half way down a stage. Accordingly, the missing arrangement described herein are not limited to use between stages of a spiral nor at locations on the spiral where concentrate is taken off the working (separating) surface of a spiral.

[0129] The mixing arrangement, which operates by deflection of a slurry part upwardly into a roof and into a configuration of projections or baffles as exemplified herein has simplified structure compared to the corresponding serpentine passage arrangement of PCT / AU2021 / 050900 and is considered to provide benefits in ease of manufacture and cost.

[0130] The provision of connected first splitters, which allows multiple splitters to be adjusted in a single operation enhances ease and efficiency in setting the splitters, and reduces the likelihood of inconsistent concentrate quality between starts or spirals of a multistart separator, by making it easier to ensure the splitters are mutually consistently set.

[0131] 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.

[0132] 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.

Claims

CLAIMS1. A spiral separator for separating more dense mineral from less dense mineral, the spiral separator having a splitting and mixing part operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into a concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the mixing arrangement comprises a deflector for deflecting at least some of the more fluid radially more outward part of the remainder part upwardly towards an upper baffle part which extends over and is spaced apart from a floor part of the mixing arrangement, and wherein the upper baffle part is configured to disperse the upwardly deflected part of the remainder part to thereby allow mixing with the less fluid radially more inward part of the remainder part, and provide reduced velocity of the more fluid radially more outward part of the remainder part prior to feeding onto the downstream spiral trough part.

2. A spiral separator in accordance with claim 1 , wherein the mixing arrangement comprises a plurality of baffle parts which extend in the direction between the upper baffle part and a floor of the mixing arrangement.

3. A spiral separator in accordance with claim 2, wherein the mixing arrangement comprises a plurality of discrete spaced apart baffle parts.

4. A spiral separator in accordance with either of claims 2 or 3, wherein the plurality of baffle parts is configured so that there is no line of sight between the deflector, and a slurry exit opening of the mixing part.

5. A spiral separator in accordance with any of claims 2 to 4, wherein the plurality of baffle parts comprises at least ten discrete baffle parts.

6. A spiral separator in accordance with any of claims 2 to 5, wherein the plurality of baffle parts is configured in at least three rows, each row comprising at least three baffle parts.

7. A spiral separator in accordance with any of claims 2 to 6, wherein the upper baffle part is configured with a number of projections having surfaces oriented to disperse at least some of the deflected part of the remainder part in directions other that the slurry flow direction of the spiral separator.

8. A spiral separator in accordance with any preceding claim, wherein the mixing arrangement comprises a guide for guiding small particles of dense material from a radially more outwards position to a radially more inwards position as they progress in the downstream direction at or close to the mixing arrangement.

9. A spiral separator in accordance with claim 8, wherein the guide is provided at or adjacent a floor part of the mixing arrangement and is provided at least partially by the deflector.

10. A spiral separator in accordance with any preceding claim, wherein a floor of the mixing arrangement is configured to provide a surface along which the less fluid part of the remainder part progresses towards an outlet of the mixing arrangement and upon which the less fluid part of the remainder mixes with the more fluid part of the remainder part.

11. A spiral separator in accordance with any preceding claim, wherein the upper baffle comprises a roof of the mixing arrangement.

12. A spiral separator in accordance with any of claims 2 to 11 , wherein at least some of the baffle parts are substantially cylindrical.

13. A spiral separator in accordance with any preceding claim, wherein the splitting arrangement is configured to split the concentrate part into first and second concentrate parts, the first concentrate part having a higher concentration of moredense mineral than the second concentrate part, and the second concentrate part having a higher concentration of dense mineral than the remainder part.

14. An apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising a splitting and mixing part for provision operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into a concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the mixing arrangement comprises a deflector for deflecting at least some of the more fluid radially more outward part of the remainder part upwardly towards an upper baffle part which extends over and is spaced apart from a floor part of the mixing arrangement, and wherein the upper baffle part is configured to disperse the upwardly deflected part of the remainder part to thereby allow mixing with the less fluid radially more inward part of the remainder part, and provide reduced velocity of the more fluid radially more outward part of the remainder part prior to feeding onto the downstream spiral trough part.

15. A spiral separator for separating more dense mineral from less dense mineral, the spiral separator having a splitting and mixing part operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder parthaving a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the splitting arrangement comprises a first splitter for splitting the first concentrate part from the second concentrate part, and a second splitter for splitting the remainder part from the second concentrate part, and wherein the first splitter is positioned downstream of the second splitter.

16. An apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising a splitting and mixing part for provision operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part; wherein the splitting arrangement comprises a first splitter for splitting the first concentrate part from the second concentrate part, and a second splitter for splitting the remainder part from the second concentrate part, and wherein the first splitter is positioned downstream of the second splitter.

17. A spiral separator for separating more dense mineral from less dense mineral, the spiral separator having a splitting and mixing part operativelyintermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part via a mixing arrangement outlet; wherein the splitting and mixing arrangement has an angular extent, between the most upstream part of the splitting arrangement and the mixing arrangement outlet, of no more than 75 degrees of a spiral turn of the spiral separator.

18. An apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising a splitting and mixing part for provision operatively intermediate upstream and downstream stage spiral trough parts of said spiral separator, the splitting and mixing part comprising: a slurry receiving region for receiving a mineral slurry flow from said upstream stage spiral trough part; a splitting arrangement for splitting the mineral slurry flow into first and second concentrate parts, the first concentrate part having a higher concentration of more dense mineral than the second concentrate part, and a remainder part having a lower concentration of dense mineral than the second concentrate part; and a mixing arrangement for mixing a more fluid radially more outward part of the remainder part with a less fluid radially more inward part of the remainder part, to provide a mixed remainder part for feeding onto the downstream spiral trough part via a mixing arrangement outlet;wherein the splitting and mixing part has an angular extent, between the most upstream part of the splitting arrangement and the mixing arrangement outlet, of no more than 75 degrees of a spiral turn of the spiral separator.

19. A spiral separator for separating more dense mineral from less dense mineral in a mineral slurry, the spiral separator having at least two substantially parallel and intertwined spiral troughs; wherein each spiral trough has an adjustable splitter for splitting at least part of the mineral slurry flow into a first and second parts, the first part having a higher concentration of more dense mineral than the second part, wherein at least two of the adjustable splitters of at least two respective spiral troughs are mechanically connected so that a single adjustment operation adjusts said at least two adjustable splitters so that the adjustment of each of the at least two adjustable splitters substantially corresponds.

20. An apparatus for a spiral separator for separating more dense mineral from less dense mineral, the apparatus comprising: a mixing arrangement for mixing a more fluid radially more outward part of a slurry from an upstream part of the spiral separator with a less fluid radially more inward part of the slurry from the upstream part, to provide a mixed slurry onto a more downstream spiral trough part; wherein the mixing arrangement comprises a deflector for deflecting at least some of the more fluid radially more outward part of the slurry upwardly towards an upper baffle part which extends over and is spaced apart from a floor part of the mixing arrangement, and wherein the upper baffle part is configured to disperse the upwardly deflected part of the slurry to thereby allow mixing with the less fluid radially more inward part of the slurry, and provide reduced velocity of the more fluid radially more outward part of the slurry prior to feeding onto the more downstream spiral trough part.

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