Technical Field

[0001] This disclosure relates generally to froth pump assemblies and parts thereof.

Background Art

[0002] Mineral processing plants often utilise a flotation process to separate the finely- ground particulates of a required mineral from waste rock. This is achieved in a flotation tank or cell in which the slurry is placed and to which fine air bubbles and reagents are added. The tank is then agitated and the resulting froth which rises to the top of the flotation cell has the fine particles of the required mineral adhering to the froth bubbles. Collection of the froth then provides a means of collecting the required concentrated mineral which has been extracted by the process.

[0003] The froth from the flotation process contains the required mineral and normally must be pumped to the next processing stage. The different types of froth produced depend a lot on the particles sizes being floated, the type and quantity of reagents and the quantity and size of the air bubbles. The froth process is continuous but there is currently no commercially-available equipment which can reduce the air content of the froth, and it is not practical to leave the froth standing until the air separates by itself before pumping the remanent particles and liquid which formed the froth.

[0004] To achieve good recovery results from the flotation process requires that the mineral ore be ground to very fine particle sizes (in some cases less than 10 micrometres). Also to achieve good mineral recovery the reagents used in the process need to be controlled, but quite often this, combined with the amount of bubbles necessary to make the process efficient, can result in a very stable and tenacious froth. These tenacious froths when left in a container would typically take 12 to 24 hours to reduce to the water and solid state only, that is, the bubbles would be extremely slow to disperse.

[0005] Horizontal centrifugal froth pumps have been used for froth pumping applications, but these are not always successful with tenacious froths. Froth is full of air, and there is a point at which the ability of a pump to tolerate froth will drop due to the effect of the air. The air tolerance of a pump is also related to the net positive suction (NPSH) characteristic; that is, the lower the net pressure available at the intake to the pump, the more likely it is that the performance will be affected. Froth pumps such as the one provided in WO 2013/144623 have been developed to specifically handle frothy fluids of this type. During the pumping operation, the heavier fraction of the fluid migrates to an outer region of the pump and a lighter fraction tends to migrate towards an inner region. The impellers for such pumps include passages passing through the impeller which allow the lighter fraction including entrained air to pass through the impeller into a collection chamber located at the rear side of a pump. The present disclosure seeks to provide an improved assembly for a horizontal centrifugal froth pump and parts thereof.

Summary of the Disclosure

[0006] In a first aspect, there is provided a rear side liner part for a centrifugal froth pump, the rear side liner part housed within a rear casing part when in use, the rear side liner part defining a collection chamber including a rear wall and a volute shaped outer peripheral side wall projecting from the rear wall to an open front side, the collection chamber further including a venting outlet wherein a portion of the outer peripheral side wall forms an upper interior surface of the venting outlet.

[0007] In certain embodiments, the venting outlet includes a vent opening in the rear wall of the collection chamber, the vent opening including a first side and a second side, wherein the radial distance from the rotation axis of the centrifugal froth pump to where the first side of the vent opening meets the outer peripheral side wall is less than the radial distance from the rotation axis to where the second side of the vent opening meets the outer peripheral side wall.

[0008] In certain embodiments, the vent opening is substantially orthogonal in shape and further includes an upper side and a lower side, wherein the upper side is in line with the upper interior surface of the venting outlet.

[0009] According to another aspect, there is provided a flow inducer for mounting within a collection chamber of a centrifugal froth pump, the flow inducer including from three to six inducer blades fitted radially and equally spaced about a collar wherein the inducer blades are shaped in the form of propeller blades wherein each of the inducer blades include a leading edge extending radially from the collar, an outer peripheral edge and a trailing edge.

[0010] In certain embodiments, each inducer blade has a trailing edge radius greater than a leading edge radius.

[0011] In certain embodiments, the collar includes a convex curved back surface facing the rear wall of the collection chamber wherein the back surface includes a plurality of grooves commencing adjacent the drive shaft and extending towards an outer circumference of the collar.

[0012] In certain embodiments, the plurality of grooves are equally spaced around the collar. In one form, the plurality of grooves are inclined in a direction opposite the rotation of the flow inducer. In a further form, the plurality of grooves are curved in a direction opposite the rotation of the flow inducer.

[0013] According to a further aspect, there is provided a centrifugal froth pump comprising a pump casing having a front side and a rear side with a pumping chamber within the pump casing, an inlet to the pumping chamber, and a discharge outlet from the pumping chamber, an impeller mounted for rotation within the pumping chamber about a rotation axis, the pumping chamber including an inner region at or near the rotation axis and an outer region remote from the rotation axis, the discharge outlet being in the outer region of the pumping chamber, the impeller including a shroud having a front face and a rear face with a plurality of pumping vanes extending from the front face, the pump further including a collection chamber at the rear side of the pump casing, the collection chamber being in fluid communication with the pumping chamber, the impeller including one or more passageway(s) extending through the shroud, one end of the passageway(s) opening into the collection chamber and the other end opening into the pumping chamber through the front face of the impeller, and a flow inducer disposed within the collection chamber, the collection chamber including a rear wall and a volute shaped outer peripheral side wall projecting from the rear wall to define an open front side facing the impeller, the collection chamber further including a venting outlet wherein a portion of the outer peripheral side wall forms an upper interior surface of the venting outlet. Brief Description of the Drawings

[0014] Notwithstanding any other forms which may fall within the scope of the methods and apparatus as set forth in the Summary, specific embodiments will now be described, by way of example, and with reference to the accompanying drawings in which:

[0015] Figure 1 is a schematic partially sectional side elevation of a centrifugal froth pump according to one embodiment;

[0016] Figure 2 is a cross-sectional detail in perspective of part of a centrifugal froth pump according to one embodiment;

[0017] Figure 3 is a sectional view of a centrifugal froth pump according to one embodiment;

[0018] Figure 4 is a front elevation of a collection chamber for a centrifugal froth pump according to one embodiment;

[0019] Figure 5 is a cross-sectional detail in perspective of the collection chamber of Figure 4;

[0020] Figure 6 is a perspective view of a flow inducer according to one embodiment;

[0021] Figure 7 is a front elevation of the flow inducer of Figure 6;

[0022] Figure 8 is a rear elevation of the flow inducer of Figure 6 and Figure 7; and,

[0023] Figure 9 is a front elevation of a flow inducer mounted in a collection chamber according to one embodiment.

Detailed Description of Specific Embodiment

[0024] Referring to Figure 1, there is illustrated a pump 10 comprising a pump housing 20 which is mounted to a support often referred to as a pedestal, base or frame (not shown). The pump housing 20 comprises an outer casing 22 which includes a front casing part 23 and a rear casing part 24 which are connected together by a series of bolts. The pump housing 20 further comprises an inlet 26 for feeding fluid to be pumped to the pump 10 and a discharge outlet 27 from which fluid can be discharged from the pump 10.

[0025] The pump housing 20 further comprises an inner liner 30 within the outer casing 22. The liner 30 includes a main liner 34 which may be in the form of a volute, wherein the radial distance of perimeter of the inner surface of the main liner spirals leading to the discharge outlet 27, as well as side liners which comprise a front liner 35 and a back liner 36. The main liner 34 illustrated comprises two parts or halves which are assembled together. The main liner can however be a one piece structure. The liner may be formed from rubber or an elastomer material and may also be formed from a metal or metal alloy. The interior of the liner 30 forms a pumping chamber 38 through which the fluid being pumped passes.

[0026] The pump 10 further includes an impeller 40 which is mounted for rotation within pumping chamber 38 about axis of rotation X-X. The impeller 40 is connected to drive shaft 18 which in turn is connected to a drive (not shown). The impeller 40 illustrated is of the semi open configuration and includes a shroud 42 having a front face 43 and a rear face 44. The impeller 40 includes a series of pumping vanes 46 projecting from the front face of the shroud. The pumping vanes 46 are evenly spaced around the rotation axis and are specially designed for handling frothy fluids and have a number of projecting portions each in the form of a curved scoop 49 which extend into the inlet 26. The impeller 40 further includes a central eye 51 which extends forwardly of the front face 43 of the shroud 42 and in use the curved scoops 49 function to drag material into the open centre of the impeller in front of the central eye 51. Other features of the impeller 40 will be described later. Auxiliary vanes 66 are provided on the back face 44 of the impeller 40. The auxiliary vanes 66 are evenly spaced around the rotation axis and have inner and outer ends. The auxiliary vanes 66 may be straight, curved or any other suitable configuration.

[0027] The pump 10 further includes a seal assembly 80 which provides a seal between the shaft 18 and the pump housing 20. The seal assembly 80 as shown is in the form of a stuffing box. [0028] As is best illustrated in Figures 2 & 3, the impeller 40 includes a series of passageways in the form of through-holes 52 arranged therein, each of which extend from the front face 43 to the rear face 44 of the impeller 40. The through-holes 52 are in the region of the rotation axis X-X and are positioned between adjacent pumping vanes 46. The through-holes 52 extend in a direction generally parallel to the axis of rotation X-X. Preferably, the number of inducer blades 71 equals the number of through-holes 52. This optimises the air flow of bubbles from the inlet 26 through the impeller 40 and flow inducer 70 into the collection chamber 60. Since the flow inducer 70 and the impeller 40 rotate as one unit, advantageously, if the number of inducer blades 71 equals the number of through- holes 52 then during assembly, it is not necessary to align the impeller 40 with the flow inducer 70 in a specific configuration as each inducer blade 71 will be similarly positioned relative to the through-holes 52 to ensure a congruous air flow through to the collection chamber 60.

[0029] The pump 10 further includes a collection chamber 60 which is located on the rear side of the pump 10 behind the impeller 40. The collection chamber 60 is adjacent with the rear face 44 of the impeller. The through-holes 52 open into the collection chamber 60. The collection chamber 60 includes a venting outlet 62 in a rear wall 63. The venting outlet 62 can be in fluid communication with a tank via a venting conduit 69, for example by means of suitable ducting, the tank for example at atmospheric pressure or under suction. The collection chamber 60 has a volute shaped outer peripheral side wall 68 and an open side 64 which faces the impeller 40 and a gap 65 which forms a transfer outlet zone between the impeller shroud 42 and casing and which provides for fluid communication between the collection chamber 60 and the pumping chamber 38. The peripheral side wall 68 is substantially parallel to the axis of rotation X-X projecting from the rear wall 63 leading to the open side 64. The volute shape of the peripheral side wall 68 means that a portion of the peripheral side wall 68 forms an upper surface of the venting outlet 62.

[0030] During operation at the inlet region 26 of a froth pump 10 there is a low pressure region at the centreline of the impeller 40 and therefore the air entrained in the frothy pumping medium tends to accumulate there. This means that the heavier fluids (the particles) travel toward the outer pump wall of the pumping chamber 38. The air accumulated in this area does not go through the pump in the normal fashion due to a combined condition of low pressure and low density. As the air accumulates at the centre line of the impeller 40 in the region of the impeller eye 51 it is removed from that region via the though-holes 52 through the impeller 40 so that the air flows into the collection chamber 60. The through holes 52 in the impeller shroud 42 allow the air to escape improving the pump efficiency. Typically, the pressure on the front side of the impeller 40 is greater than the pressure in the collection chamber 60 which causes the air to flow through the through- holes 52. The air flows through the impeller through holes 52 into the collection chamber 60 and then out through the venting outlet 62.

[0031] The pump 10 further includes a flow inducer 70 which is mounted for rotation within the collection chamber 60. The flow inducer 70 is operatively mounted to the drive shaft 18 so that in operation both the impeller 40 and the flow inducer 70 are rotated together by the drive shaft 18. In use, the inducer blades 71 are angled from 5 to 15 degrees so as to cause a generally axial flow of material (that is, a flow generally in line with the rotation axis X-X) through the collection chamber 60 and out towards the venting outlet 62.

[0032] Referring to Figures 4 and 5 there is shown a rear side liner part 15 which is housed within the rear casing part 24 when forming part of the pump assembly. The rear side liner part 15 defines the collection chamber 60. The collection chamber includes a rear wall 63 and a volute shaped outer peripheral side wall 68 which projects from the rear wall 63 to define an open front side 64. The collection chamber 60 further includes a venting outlet 62 which includes an upper interior surface 120 which is contiguous with the outer peripheral side wall 68 at the location of the venting outlet 62. The outer peripheral side wall 68 and the upper interior surface 120 of the venting outlet 62 are generally parallel with the rotation axis X-X.

[0033] The venting outlet 62 includes a vent opening 105 in an upper region of the rear wall 63 of the collection chamber 60. In this embodiment, the vent opening 105 is generally orthogonal in shape and includes a first side and second side 116, 117 as well as an upper side 110 and a lower side 118. The upper side 110 of the vent opening 105 is shown as a continuation of the surface of the outer peripheral side wall 68 moving anti clockwise from the second side 117 to the first side 116.

[0034] Best shown in Figure 4, the outer peripheral side wall 68 is in the form of a volute which provides that the radial distance from the rotation axis X-X to the outer peripheral side wall 68 gradually increases from the point where the outer peripheral side wall 68 meets the first side 116 moving anti clockwise around the outer peripheral side wall 68 until the outer peripheral side wall 68 meets the second side 117. The outer peripheral side wall 68 is at its greatest radial distance from the rotation axis as it meets the second side 117 of the vent opening 105 and thereafter moving anti clockwise forms the upper side 110 of the vent opening 105. Due to the volute shape of the outer peripheral side wall 68, the radial distance D 1 from the rotation axis X-X to where the first side 116 of the vent opening 105 meets the outer peripheral side wall 68 is less than the radial distance D2 from the rotation axis X-X to where the second side 117 of the vent opening 105 meets the outer peripheral side wall 68.

[0035] The radial distance from the rotation axis X-X to the outer peripheral side wall 68 gradually increases in the direction of rotation of the flow inducer 70, and the impeller 40. In Figures 4, and 5, the direction of rotation of the flow inducer 70 and the impeller 40 would be anti-clockwise. If the direction of rotation of the flow inducer 70 and the impeller 40 was in the clockwise direction, then the radial distance of the outer peripheral side wall 68 would increase in the clockwise rotation as it moves around the collection chamber 60 (i.e. opposition direction to what is depicted in Figures 4 and 5).

[0036] The volute shape of the outer peripheral side wall 68 provides that entrained material circulated in the collection chamber 60 by the flow inducer 70 rotating in an anti clockwise direction travels along the outer peripheral side wall 68 until the outer peripheral side wall 68 meets the second side 117 of the venting opening 105. The material is then directed into the vent opening 105 by a cut water portion 119. The cutwater portion 119 is provided by part of the first side 116 of the vent opening 105 which is located above where the outer peripheral side wall 68 meets the first side 116. The volute shape of the outer peripheral side wall 68 and the location of the cutwater portion 119 prevents entrained material continuously circulating around the outer peripheral side wall 68 providing more efficient ejection of entrained material from the collection chamber to the venting outlet 62, as well as significantly reducing erosive wear on the outer peripheral side wall 68 of the collection chamber 60 and the rear side liner part 15.

[0037] As best shown in Figure 5, the venting outlet 62 includes an upper interior surface 120 which is contiguous with the outer peripheral side wall 68. Otherwise stated, the upper interior surface 120 of the venting outlet 62 which leads from the vent opening 105 in the collection chamber 60 to the venting conduit 69 forms a continuous surface with the outer peripheral side wall 68 at the location of the venting outlet 105. By providing an upper interior surface 120 of the venting outlet 62 in line with the surface of the outer peripheral side wall 68, entrained material has an unobstructed path to the venting outlet 62 when circulating around the inside of the outer peripheral side wall 68 of the collection chamber 60.

[0038] Figures 6, 7 and 8 depict a flow inducer 70 in accordance with an embodiment of the present disclosure. The flow inducer 70 is for mounting within the collection chamber 60 of a centrifugal froth pump. The flow inducer 70 includes four inducer blades 71 fitted radially and equally spaced about a collar 73. The present embodiment may correspond and work best with an impeller 40 including fourthrough-holes 52 as shown in Figure 3.

[0039] The inducer blades 71 are shaped in the form of propeller blades wherein each of the inducer blades 71 includes a leading edge 74 extending radially from the collar 73, an outer peripheral edge 75 and a trailing edge 76 which also extends radially from the collar 73 to meet the outer peripheral edge 75 of the inducer blade 71. The leading edge 74 is thicker (i.e. has a greater width between the front face and the rear face of the inducer blade) than the trailing edge 76.

[0040] The inducer blades 71 further include a curved leading edge transition, or radius 90 between the leading edge 74 and the outer peripheral edge 75 and a curved trailing edge transition, or radius 95 between the trailing edge and the outer peripheral edge 75. The radius 90 is smaller than the radius 95.

[0041] The inducer blades 71 include a front face 96 which is facing the rear of the impeller 40 when in use, and a rear face 97 (Figure 8) which faces the rear wall 63 of the collection chamber 60. The front face 96 and the rear face 97 are shaped with a curved surface or twist whereby the faces 96, 97 are not planar in shape.

[0042] As best shown in Figure 8, the collar 73 includes a curved back surface 77 which faces the rear wall 63 of the collection chamber 60 when in use. The curve of the back surface is of a convex shape and begins adjacent where the collar 73 meets the drive shaft 18 and continues until an outer circumference 79 of the collar 73. The curved back surface 77 includes a plurality of grooves 78 which commences adjacent the drive shaft 18 and extends towards the outer circumference 79 of the collar 73. The grooves 78 may be equally spaced around the curved back surface 77 of the collar 72 and may comprise from four to ten in number. In the present embodiment depicted in Figure 8, there are eight grooves 78 equally spaced around the curved back surface 77 of the collar 72. The preferred number of grooves 78 prevents material from the froth and slurry from getting entrapped in the gap 67 between the flow inducer 70 and rear wall 63 of the collection chamber 60.

[0043] The grooves 78 may be inclined in a direction opposite to a direction of rotation of the flow inducer 70 and impeller 40 which is shown by the arrow at the top of the flow inducer 70 in Figure 8. The grooves 78 may also be backwardly curved with respect to the direction of rotation of the flow inducer 70, whereby the grooves 78 are not straight but curved over their length leading from their commencement adjacent the drive shaft 18 to the outer circumference 79 of the collar 73. The grooves 78 assist by preventing build-up of particles adjacent the shaft sleeve and transport these to the collection chamber 60.

[0044] In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "front" and "rear", "inner" and "outer, "above", "below", "upper" and "lower" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

[0045] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0046] In this specification, the word "comprising" is to be understood in its "open" sense; that is, in the sense of "including", and thus not limited to its "closed" sense; that is, the sense of "consisting only of . A corresponding meaning is to be attributed to the corresponding words "comprise, "comprised" and "comprises" where they appear.

[0047] Furthermore, invention(s) have described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Table or Parts

Pump 10

Housing 20

Outer Casing 22

Front Casing 23

Rear Casing 24

Inlet 26

Discharge outlet 27

Inner liner 30

Main liner 34

Front liner 35

Back liner 36

Pumping chamber 38

Impeller 40

Axis of rotation X-X

Drive shaft 18

Shroud 42

Front face 43

Rear face 44

Pumping vane 46

Projecting portion 49

Impeller eye 51

Through-hole 52

Auxiliary vane 66

Seal assembly 80

Rear side part 15

Gap 65

Collection chamber 60

Rear wall 63

Open side 64

Outer peripheral side wall 68

Venting conduit 69

Gap 67 Flow inducer 70

Inducer blades 71

Collar 73

Leading edge 74

Outer peripheral edge 75

Trailing edge 76

Front face 96

Rear face 97

Leading edge transition 90

Trailing edge transition 95

Back surface 77

Grooves 78

Outer circumference 79

Venting outlet 62

Vent opening 105

Upper side 110

Lower side 118

First side 116

Second side 117

Cutwater portion 119

Upper interior surface 120