WO2007017737A1

WO2007017737A1 - Transportation of particulate material

Info

Publication number: WO2007017737A1
Application number: PCT/IB2006/002155
Authority: WO
Inventors: Ian Harding; Leonard James Harding; Edward Theodorus Pienaar; Edgar Thomas Harding
Original assignee: Ian Harding; Leonard James Harding; Edward Theodorus Pienaar; Edgar Thomas Harding
Priority date: 2005-08-08
Filing date: 2006-08-04
Publication date: 2007-02-15

Abstract

The invention provides a method and apparatus for installation for transporting a particulate material along a conduit by means of a fluid. The method involves injecting particle-free streams of fluid in the form of jets into the conduit and into the particle-containing fluid flowing along the conduit, the jets being aligned to cause downstream flow of the particle-containing fluid along a helical path. The apparatus or installation (50) comprises a conduit (24) provided through a wall thereof with a plurality of fluid inlets (46) for injecting streams of particle-free fluid and jets through the wall and into the conduits. The fluid inlets (46) are arranged to align the jets in directions as selected to cause a downstream flow of particle-containing fluid along a helical path along the conduit.

Description

TRANSPORTATION OF PARTICULATE MATERIAL

THIS INVENTION relates to the transportation of a particulate material along a conduit by means of a fluid. More particularly, the invention relates to a method of such transportation; to an apparatus or installation for such transportation; and to a fitting or sub-assembly forming part of the apparatus. The invention is of particular application in, but is not restricted to, the transportation of diamondiferous grit or gravel by means of water, which grit or gravel tends to settle out of motionless water.

According to one aspect of the invention there is provided a method of transporting a particulate material along a conduit by means of a fluid by feeding a fluid containing particulate material entrained therein into and along the conduit in a desired downstream direction, while maintaining a sufficiently turbulent fluid flow in the conduit to prevent particles from settling from the fluid in the conduit, the method comprising injecting a plurality of particle-free streams of said fluid in the form of jets through a wall of the conduit and into the particle-containing fluid flowing along the conduit, the jets being aligned in directions selected to cause downstream flow of the particle-containing fluid along a helical path, and the injecting of the fluid into the conduit being at a rate which maintains said entrainment of the particulate material in the fluid. The invention typically involves transportation of particulate material by a fluid of a single phase, and while it in principle extends to the transportation of a particulate material by a fluid in the gas phase, it is expected that the invention will usually be applied to the transportation of a particulate material by means of a fluid in the liquid phase, such as liquid water, and this application should be borne in mind during consideration of what follows.

The feeding of the particle-containing fluid may into an open end of the conduit, forming a mouth or particle inlet into the conduit, this feeding being from a source of supply of the particle-containing fluid in which the particles are entrained and are maintained in a suspended state by turbulence in the fluid achieved, for example, by stirring the fluid. Any desired method may be employed for the stirring, which may be effected, for example, mechanically by means of a stirrer, or hydraulically by means of one or more jets of fluid, acting on the source of supply of the particle-containing fluid. Instead, as described in more detail hereunder, the particle-containing fluid may simply be sucked into the mouth of the conduit, via a particle inlet in the form of a suction nozzle, from a bed of the particulate material.

For example, a jet of the particle-free fluid from a source of supply thereof under pressure may be directed into the source of supply of the particle- containing fluid, the jet being directed also at the mouth or particle inlet of the conduit, to carry particles and fluid into the conduit. The injecting of the streams of particle-free fluid into the conduit may be of fluid from the same source of supply of fluid under pressure, which may be a pump for pumping a liquid fluid such as water, and the injecting may take place at or adjacent and downstream of the mouth or particle inlet of the conduit, the streams being arranged to cause said helical flow in the form of a swirl or vortex of the particle-containing fluid in a downstream direction away from the mouth or particle inlet, at least at a position in the conduit adjacent and downstream of the positions where the streams of particle-free fluid are injected into the conduit.

Naturally, instead, the streams of particle-free fluid may be injected into the conduit at selected positions spaced along the length of the conduit, or indeed all the way along the conduit at more or less evenly spaced or dispersed positions. Broadly, however, the injecting of at least some of the streams may be in the form of jets aligned in directions selected so that the jets cause helical flow of the particle- containing fluid in the conduit in the downstream direction along the conduit. Typically, the conduit will be circular in cross-sectional outline, the injection of at least some of the streams being effected at positions spaced both axially and circumferentially from one another and dispersed over the inner surface of the wall of the conduit. As indicated above, this may be along substantially the full length of the conduit, although the injection may be dispensed with at certain parts of the conduit, such as at bends or elbows, or it may take place, as indicated above, only at selected positions such as at or adjacent the particle inlet of the conduit. In a particular embodiment, the injecting of the streams may be effected at positions spaced along a helical path extending along the inner surface of the wall of the conduit.

In a particular version of the method, the particle-free fluid for the streams is fed under pressure into a sleeve, jacket or shell, which is usually tubular and is usually straight and cylindrical, although it may be curved or tapering, surrounding the conduit at or adjacent the mouth or particle inlet of the conduit, or spaced from the mouth or particle inlet, or indeed surrounding more or less the full length of the conduit. The streams in this case may be injected from the shell into the conduit, via injection nozzles providing passages leading from the shell into the conduit. The nozzles may be more or less evenly spaced and spread out or dispersed from one another, over the surface of the conduit in the shell, so that the streams likewise are more or less evenly spaced from one another, over the length of the shell and over the circumference of the conduit in the shell. In this version of the method, the injecting of each stream into the conduit may take place via a tubular and usually straight injection nozzle projecting radially outwardly from the conduit, the nozzle having an inlet at its outer end in the interior of the shell and an outlet at its inner end, the inner end of the nozzle being flush with the inner surface of the conduit wall. This leaves the inner surface of the conduit wall free of any obstructions arising from the nozzles, to provide the particle-containing fluid with unimpeded flow along the conduit. More particularly, the injecting of at least some of the streams into the conduit may thus, as indicated above, be from a shell surrounding the conduit, fluid flow into the conduit taking place from an annular space defined between the conduit and the shell and fluid being fed under pressure from a source of particle-free liquid into the shell.

In a particular embodiment of the method, the particle-containing fluid may, as suggested above, be fed into a particle inlet at an open upstream end of the conduit, the feeding being by locating the upstream end of the conduit at or adjacent and spaced from particles, for example in a particle bed which may be under a body of water, to be entrained in the fluid, flow of fluid along the conduit arising from injection of the streams into the conduit giving rise to a pressure drop at said open upstream e nd from the exterior of t he conduit to the i nterior of the conduit, which pressure drop causes flow of fluid, for example via a suction nozzle, into the open upstream end, the flow entraining particles in the fluid as it enters the conduit and the flow drawing the particles into the particle inlet of the conduit. The inlet may often form a lowermost extremity of the conduit, so that the conduit functions as a fluid lift for the particles, the transporting of the particles acting to raise them upwardly away from the particle inlet along the interior of the conduit. Instead, however, and as suggested above, the particle-containing fluid may be fed into a particle inlet at an open upstream end of the conduit, the feeding being by withdrawal of particle- containing from a volume of fluid which is maintained in a state of turbulence whereby the particles therein are held in a suspended state.

It is expected that, in a particular application of the method, the fluid will be liquid water and the particulate material will be gravel or grit, for example diamondiferous gravel or grit, the method including pumping the water from a water supply to the conduit to provide the particle-free fluid which is injected into the conduit.

Naturally, the particles of the particulate material will usually be separated from the fluid, after discharge thereof from a particle outlet of the conduit, the fluid, if desired, being recycled or re-circulated from such separation to the source of supply of the fluid under pressure, for re-use of the fluid. According to another aspect of the invention an apparatus or installation for the transportation of a particulate material entrained in a fluid in a desired downstream direction along a conduit in accordance with the method of the invention as defined and described above comprises a conduit for leading a flow of particle-containing fluid from a particle inlet into the conduit to a particle outlet from the conduit, the apparatus or installation being provided, through a wall of the conduit, with a plurality of fluid inlets for injecting streams of said fluid in particle-free form as jets through the wall and into the conduit, the fluid inlets being located between the particle inlet and the particle outlet and the fluid inlets being arranged to align the jets in directions selected to cause a downstream flow of particle-containing fluid along a helical path in the conduit and to permit fluid injection into the conduit at a rate which promotes entrainment of particles in the downstream fluid flow.

The apparatus or installation may be fixedly anchored in position, in which case it can be regarded as an installation, or it may be mobile or movable, for example by being located on a floating platform, such as a boat, ship or barge, in which case it can be regarded as an apparatus.

The fluid inlets may comprise passages arranged to inject the jets in directions which are aligned to have a downstream component in the direction of particle-containing fluid flow along the conduit, at least some, and preferably all, of said passages being arranged to inject jets in directions which also have a tangential component, in the same circumferential direction, relative to said direction of particle- containing fluid flow along the conduit, for causing the helical flow of particle- containing fluid in the downstream direction. Typically, the conduit will be circular in cross-sectional outline, the fluid inlets being located at positions spaced axially and circumferentially from one another and dispersed over at least part, and optionally substantially all, of the inner surface of the wall of the conduit. The fluid inlets may thus be provided at certain parts of the conduit, for example at or adjacent its particle inlet, or they may be provided more or less along the full length of the conduit, being omitted o nly at places such a s bends or elbows, where they may be found to be inconvenient, and where their omission does not interfere with the flow of particle- containing fluid along the conduit. In a particular embodiment, the fluid inlets may be located at positions spaced along a helical path along the inner surface of the conduit.

Each said inlet may be defined by a tubular nozzle projecting outwardly from the conduit, the nozzle typically being straight rather than curved and having an inlet at its outer end and an outlet at the inner surface of a wall of the conduit, the conduit being flush with the inner surface of the wall so that the interior of the conduit is substantially free of any obstruction arising from the nozzle.

The apparatus or installation may include at least one tubular shell surrounding at least part, and optionally substantially all, of the conduit, the fluid inlets into the conduit leading into the conduit from an annular space defined between the conduit and a said shell, at least one said shell being provided, intermediate its ends, with a fluid inlet for particle-free fluid under pressure. Thus, a single shell, in which associated fluid inlets are provided, may be located at or adjacent the particle inlet, or several such shells, in each of which associated fluid inlets are provided, may be located at desired positions along the conduit. In a particular embodiment, the conduit is of composite construction, being made up of a series of modules connected together end-to-end, each module comprising a length of conduit provided with its own shell and its own fluid inlets, at least one of the modules being provided with a fluid inlet into its shell, the series optionally being 5 interrupted, where convenient, by bends, elbows or the like.

Each module may include a plurality of fins extending along the length of the module, the fins being circumferentially spaced, preferably equally circumferentially spaced, around the associated length of conduit and radiating

I O therefrom to the associated shell, each fin having at least one gap therein permitting fluid flow from one side of the fin to the other.

The apparatus or installation may include a source of supply of particle- containing fluid in the form of a container for holding therein particle-containing fluid 15 having particles entrained therein, the particle inlet of the conduit being connected to an outlet from the container. Instead, the a pparatus o r installation m ay include a suction nozzle forming the particle inlet of the conduit and connected to the conduit.

Naturally, the apparatus or installation may include a particle separation -0 station at the downstream end of the conduit.

When the source of supply of the particle-containing fluid is a container, it may be a bin or hopper, which may be provided with a stirring device such as a mechanical impeller or stirrer, or which may be hydraulically stirred by jets of fluid, for

25 maintaining entrainment of particles suspended in the liquid held in the bin or hopper. The container may be a tank for holding a fluid in the form of a liquid such as liquid water, the tank having an outlet, which may be at a low level therein, leading into a mouth forming an inlet into the conduit.

The apparatus or installation will typically include a source of supply of particle-free fluid in the form of a liquid such as water, the source of supply being for supplying liquid under pressure, for example a single pump, and the pump may be arranged to project a jet of liquid into a liquid containing the particles in the bin or hopper, the jet being directed at the outlet of the bin or hopper, for feeding liquid and particulate material into the mouth of the conduit. The same pump may also be arranged to feed liquid under pressure to the nozzles, which nozzles, although they can in principle be curved, will typically be straight and tubular in shape, feeding inwardly through a wall of the conduit, into the interior of the conduit. The nozzles may, as indicated above, be more or less evenly spaced and spread out from one another, over t he s urface of the wall of the conduit, a nd m ay b e d irected i nto t he conduit in directions selected so that streams of liquid fed via the nozzles into the particle-containing liquid in the conduit combine to cause the liquid to swirl in a downstream direction away from the mouth of the conduit, along a helical path which can be regarded as a vortex. The nozzles may be located at or adjacent the mouth or inlet of the conduit, and/or at spaced positions downstream thereof, of all the way along the conduit.

In a particular embodiment of the apparatus or installation, the part of the conduit containing the nozzles through its wall may, as indicated above, be enclosed by a shell, which may be tubular in shape, being in the nature of sleeve or jacket spaced radially from the conduit, the shell having a fluid inlet connected by a flow I ine s uch a s a p ipe t o t he o utlet of t he p ump, so t hat all t he n ozzles c an b e supplied with liquid at more or less the same pressure. The shell inlet may be through its outer curved surface, for example midway along its length or adjacent one end thereof. Instead, the shell may be open at one or both ends thereof, one end acting as its inlet and the other end thereof acting as an outlet, leading for example into an inlet end of an adjacent shell.

While the apparatus or installation may have one fitting comprising a length of conduit, and a said shell, with the associated nozzles, at or adjacent the bin or hopper, two or more fittings may be provided, optionally spaced from one another or end-to-end with another, and arranged in a series extending downstream from the bin or hopper, each with its associated length of conduit, shell, nozzles and an inlet connected to the pump, to act as boosters for boosting flow of particles along the conduit, if needed, for example if the conduit is particularly long. Naturally, each shell may be supplied with liquid under pressure from its own pump, there being for example several pumps, one for each shell.

The invention extends to a fitting or sub-assembly for forming part of an apparatus or installation as defined and described above, the fitting or sub-assembly comprising a length of conduit open at each end thereof, the conduit length being located in and connected to a tubular shell which is concentric therewith, an annular space being defined between the conduit length and the shell, the fitting or sub- assembly having an annular connecting flange at each end thereof and including a plurality of fluid inlets into the interior of the conduit length from said annular space for injecting streams of particle-free fluid as jets through the wall and into the conduit length, the fluid inlets being arranged to align the jets in directions selected to cause fluid flow in one direction along the conduit length and along a helical path.

The fluid inlets may comprise passages arranged to inject the jets in directions which have a longitudinal component relative to the length of conduit, at least some of said passages b eing a rranged to i nject j ets i n directions which a lso have a tangential component, in the same circumferential direction, for causing helical flow of fluid along the length of conduit. The length of conduit may be circular in cross-sectional outline, the fluid inlets being located at positions spaced axially and circumferentially from one another and dispersed over the inner surface of the wall of the conduit length. In particular, the fluid inlets may be located at positions spaced along a helical path on the inner surface of the conduit length. Each fluid inlet may be defined by a tubular nozzle projecting outwardly from the length of conduit, the nozzle having an inlet at its outer end in the interior of the shell and an outlet at the inner surface of a wall of the length of conduit, the outlet being flush with the inner surface of the conduit length wall so that the interior of the length of conduit is substantially free of any obstruction arising from the nozzle. The fitting or sub- assembly may include a plurality of fins extending along the length of conduit, the fins being equally circumferentially spaced around the length of conduit and radiating therefrom to the shell, each fin having at least one gap therein permitting fluid flow from one side of the fin to the other.

For each application or use, the number of nozzles, their spacing from one another on the surface of the conduit, their respective orientations with regard to the conduit and with regard to one another, their sizes and the flow rates possible therethrough, can be established by routine experimentation, so as to achieve optimal or acceptable results. Similar considerations apply to the pump or pumps, and to the rate at which fluid is delivered into the manifold and into the bin or hopper.

The invention will now be described, by way of non-limiting illustrative example, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 shows a schematic flow diagram of an installation according to the present invention; Figure 2 shows a schematic three-dimensional view of a fitting or sub- assembly forming part of the installation of Figure 1 ;

Figure 3 shows a partially exploded view of the fitting of Figure 2; Figure 4 shows parts of the fitting of Figure 2 in disassembled form; Figure 5 shows a schematic side elevation of a different hopper for the installation of Figure 1 ;

Figure 6 shows a schematic partial side elevation of another apparatus or installation in accordance with the present invention;

Figure 7 shows a schematic view similar to Figure 6 of a variation of the apparatus or installation of Figure 6; Figure 8 shows a detail in schematic side elevation of a pipe length of a fitting forming part of the installation of Figure 7;

Figure 9 shows, on an enlarged scale, a schematic end elevation of the fitting whose pipe length is shown in Figure 8;

Figure 10 shows a schematic detail in side elevation of a footpiece forming a suction nozzle for the installation of Figure 7; and Figure 11 shows a schematic underside plan view of the footpiece or suction nozzle of Figure 10.

In Figure 1 of the drawings, reference numeral 10 generally designates

5 an installation in accordance with the invention. The installation 10 comprises a pump 12, a bin or hopper in the form of a tank 14, a fitting or sub-assembly in the form of module 16 in accordance with the present invention, and a settling station

18. Flow lines in the form of pipes 20 and 22 respectively lead from the pump 12 to the tank 14 and fitting 16, the pipe 20 branching from the pipe 22. A conduit in the

IO form of a pipe 24 leads from the tank 14 via the fitting 16 to the settling station 18, a solid flow line 26 leads from the settling station 18 towards downstream processing, and a return or recycle liquid flow line 28 leads from the settling station 18 to the pump 12. The tank 14 is shown provided with a mechanical stirrer 30, and the pipe

20 is shown entering the tank 14 and extending across its interior below the stirrer

15 30. The pipe 20 has an outlet which functions as a nozzle, and is closely spaced from and directed at the inlet to the conduit 24, said pipe 20 being shown directing a jet 32 of liquid at said inlet.

The installation 10 is shown associated with a diamond mine, the pump -¹O 12, tank 14 a nd fitting 16 being underground in the mine, and the settling station being at the surface 34. The particulate material to be transported will thus be diamondiferous grit or gravel, the liquid being water.

With reference a lso to F igures 2-4, the fitting 1 6 comprises a central 25 tubular length 36 of pipe forming part of the conduit 24, the length 36 being located in a housing or manifold 38 provided by a tubular outer shell 40, arranged concentrically around the length 36. The shell 40 is tubular and is provided with an inlet 42 adjacent its upstream end and attached to the pipe 22, and a pair of annular end walls 44, whereby the shell 40 is sealed to and concentrically spaced from the length

5 36. The fitting 16 comprises six nozzles 46 arranged in a helix, the helix extending over the outer surface of the length 36. Each nozzle is in the form of a straight tube projecting outwardly from the length 36 to terminate in an inlet located in the housing 38, each nozzle having an inner end providing its outlet and forming a water inlet into the length 36 of the conduit 24, the inner end of the nozzle 46 being flush with the

0 inner surface of the wall of the length 36. The inner end is received in a passage 48 provided therefor in the wall of the length 36 (Figure 4). This arrangement leaves said inner surface of the conduit 24 unobstructed with regard to flow of water and particles along its length, and provides a series of water inlets into the conduit, the series extending along a helical path along the inner surface of the length 36.

I 5

Each nozzle tube 46 has an axis inclined at an angle to the axis of the length 36, so that it can inject a stream of water in a downstream direction as a jet into the conduit 24; and the axis of each nozzle tube 46 is also directed in a tangential or circumferential direction, relative to the downstream direction. Each

.0 nozzle is thus aligned relative to the downstream direction so that it in use injects a jet of water into the conduit length 36 in a direction which has a downstream component and which has a tangential component. All the nozzle tubes 46 are directed in the same tangential or circumferential direction relative to the length 36, so that streams of water injected via the nozzle tubes 46 into the conduit 24 will

15 impart a helical swirl to water containing particles of grit or gravel flowing in a vortex in a downstream d irection from the inlet of the conduit 24 away from the tank 14 towards the settling station 18, the water flowing along a helical path.

In accordance with the method of the invention, a source of supply of diamondiferous grit or gravel is maintained in the tank 14, by feeding the grit or gravel into the tank through a pressure lock, while water is pumped into the tank 14 by the pump 12 along the pipe 20. The stirrer 30 stirs the contents of the tank 14 in the direction of the diagrammatic liquid circulation arrows shown in the tank 14, to keep the grit or gravel entrained and suspended in the tank 14. Pressure in the tank 14 feeds water into the mouth of the conduit 24 which forms a particle inlet into the conduit 24, and this feeding is assisted by the location of the nozzle outlet of the pipe

20 in the tank 14, so that it directs the jet 32 of water at and into the particle inlet to the conduit 24.

The pump 12 also feeds water along the pipe 22 into the inlet 42 of the shell 40. Water in the housing 38 flows via the nozzle tubes 46 into the length 36, and imparts a helical swirl of the nature of a vortex to the water and grit or gravel flowing along the conduit 24 away from the tank 14 towards the settling station 18, so that the water follows a helical path in the downstream direction. At the settling station 18, the grit or gravel is separated by settling from the water, the grit or gravel passing along the flow line 26, provided for example by a conveyor belt (not shown) to downstream processing thereof, and the water being re-circulated to the pump 12 along the flow line 28 under gravity. Particle-free water make-up can be supplied to the installation 10 from time to time or continuously, as required to make up for any water losses, water being lost for example along flow line 26 with the grit or gravel. It is an advantage of the invention illustrated in Figures 1 - 4 that water flow along the conduit is maintained with sufficient turbulence to prevent settling out of grit or gravel in the conduit 24, so that grit or gravel can be efficiently and effectively transported from a position underground in the tank 14, to the ground surface 34. This transport can be around b ends, elbows or corners, such as the more or less 90° corner shown at 50 in Figure 1 , but care should be taken that the radius of curvature of such corners is sufficiently large to avoid unwanted settling of particles there. A further advantage of the invention is that the pump 12 does not normally pump any grit or gravel, so that damage caused to its impeller by grit or gravel is substantially reduced, if not eliminated.

In Figure 5 the same reference numerals are used as in Figures 1 - 4, to designate the same parts, unless otherwise specified. The tank 14 of Figure 1 is, in Figure 5, replaced by a fitting comprising a downwardly tapering conical hopper 16.1 , and is shown indirectly connected to a straight fitting 16, constructed as described with reference to Figures 2 - 4, being connected to the fitting 16 by a curved or semi-toroidal fitting 16.2. Thus, the h opper 16.1 can b e regarded as a downwardly tapering, conical, open-topped version of the fitting 16, having a tapering inner wall 36.1 spaced inwardly from a tapering outer shell 40; and the curved fitting 16.2 can likewise be regarded as a semi-toroidal version or variation of the fitting 16, having a curved length 36.2 located inside a curved outer shell 40.2.

The hopper 16.1 and the curved fitting 16.2 respectively have inlets 42.1 and 42.2 corresponding to the inlet 42 of the fitting 16. The nozzle tubes 46 of Figures 2 - 4 are, for clarity of illustration, omitted and not shown in Figure 5, but their spiral arrangement in the fitting 16.2 is essentially the same as their arrangement in the fitting 16, bearing in mind and taking into account the curved nature of the fitting 16.2. In the case of the hopper 16.1 , however, the nozzle tubes are confined to the part of the hopper 16.1 below the level of the inlet 42.1 , being otherwise arranged to cause a swirl or vortex in the hopper 16.1.

Operation of the construction shown in Figure 5 is similar to that of Figures 1 - 4, diamondiferous grit or gravel being charged from above into the hopper 16.1 , and being kept in suspension by hydraulic stirring by jets of water introduced into the hopper 16.1 via the inlet 42.1 and via the nozzle tubes. The jets of water entering the hopper 16.1 keep the water level in the hopper 16.1 at a desired elevation, while water is withdrawn from the lower end of the hopper 16.1 by the fittings 16 and 16.2, whose respective inlets 42 and 42.2 are also fed with water under pressure, and which function in the fashion described above with reference to the fitting 16 of Figures 1 - 4, to carry water and suspended grit or gravel away from the hopper 16.1 in a downstream direction and to a higher level.

Turning to Figure 6, once again, like reference numerals refer to like parts, unless otherwise specified. The apparatus of Figure 6 is generally designated

50 and is for raising diamondiferous grit or gravel from the bed 52 of a body of water

54 such as a stream or the sea. Three pumps 12 are illustrated on the deck 56 of a barge (not otherwise shown) and a stack of fittings is shown, two of which are designated 16 and are modules similar to the module 16 of Figures 1 - 4 and one of which is different and is designated 16.3. The stack leads upwardly from the bed 52 to the surface of the body of water 54. The fittings 16, 16.3 are connected end-to- end with the fitting 16.3 lowermost by means of their flanges 44, which have bolt- holes (not shown) for this purpose (the lengths 36 of conduit being of the same length as the shells 40), the uppermost fitting 16 feeding into the pipe 24 for downstream processing on the deck 56. Each of the pumps 12 feeds via a pipe 22 to the inlet 42 or 42.3, as the case may be, of an associated respective fitting 16, 16.3. In other examples the number of fittings 16 in the stack can be increased, in modular fashion, so that there are more than two.

It is to be noted, in particular, that the fitting 16.3 has an upwardly tapering outwardly-belled lower end 58, forming a suction nozzle, which is also provided with a supply of nozzle tubes (see 46 in Figures 2 - 4), spirally arranged and pointing in downstream and tangential / circumferential directions, similarly to those in the upright straight part of the fitting 16.3 and in the fittings 16. The nozzle tubes in the lower end 58 of the fitting 16.3 stir up grit and gravel from the bed 52 and bring it into suspension in its interior. From the interior of the nozzle 58 this grit or gravel is raised upwardly through and along the fittings 16.3 and 16 to the pipe 24, which discharges the grit or gravel onto the barge for downstream processing (see settling section 18 and flow line 26 in Figure 1). Water for the pumps 12 is simply withdrawn from the body of water 54 and, after settling at the station 18, is returned to the body of water 54, while the jets issuing from the various nozzles 46 causing the upward flow in the stack give rise to a pressure drop from the surrounding water into the suction nozzle 58. In Figure 7, the same reference numerals are used as in Figure 6, unless otherwise specified, to designate the same parts. The apparatus or installation of Figure 7 is thus also generally designated 50, and is also for lifting diamondiferous grit or gravel from the bed 52 of a body of water 54. A single pump 12 is illustrated on the deck 56, the pump 12 in Figure 7 being shown (as is the case with the pumps 12 of Figure 6) having its inlet connected to a conduit in the form of a pipe 60 leading from below the surface of the body of water 54 to the pump inlet.

The stack of fittings shown in Figure 7 comprises fittings in the form of modules but somewhat different from those illustrated in Figure 6, there being three fittings 16.4 stacked end-to-end, one on another, on the uppermost of which is stacked a fitting 16.5, the fittings 16.4 and 16.5 being constructed as described hereunder. The stack leads from the fitting 16.5 via a bend or elbow 62 into the pipe

24, which in the case of Figure 7 is made up of a plurality of fittings 16.4, connected in s eries, e nd-to-end. T he p ipe 24 has, i ntermediate its downstream e nd a nd the elbow 62 at the top of the stack, a fitting 16.5, arranged in series with the fittings

16.4, the fitting 16.5 being straddled by a pair of the fittings 16.4. It is to be noted that the bend or elbow, while having the same inner diameter as the pipe lengths

36.1 of the fittings 16.4, 16.5, is bent over a relatively large or long radius, to promote good g ravel a nd g rit t ransport a round the bend 62, without s ettling. T he stack of fittings, as is the case with Figure 6, forms an upstream end portion of the conduit 24.

In Figure 7, the pump 12 is shown pumping via pipe 22 into the inlet

42.5 of the fitting 16.5 of the stack, and via a branch pipe formed by a T-piece 64 into the inlet 42.5 of the fitting 16.5 of the pipe 24. As will be noted from Figure 7, the inlets 42.5 into the fittings 16.5 are centrally positioned along the lengths of the fittings 16.5, and not adjacent their upstream ends, as is the case with the inlets 42 and 42.3 respectively into the fittings 16 and 16.3 in Figure 6. Furthermore, it is to be noted that the fittings 16.4 have no inlets whatsoever, and are not connected directly 5 to the pipe 22, but are connected thereto, indirectly, via the ends of their shells 40.3 (see Figure 9).

To permit easy illustration of a modification of the apparatus or installation 50 of Figure 7, the pipes 22, 24 are shown with respective breaks or gaps

0 therein, to show an alternative to remote downstream particle separation and processing of the outflow of the pipe 24 on the deck 56. In this alternative, an elbow or bend 62, separated by a single fitting 16.4 from the elbow or bend 62 connected to the fitting 16.5 at the top of the stack, is shown discharging downwardly via an inclined sieve or screen 66 into a pan 68 supported adjacent the stack above the

5 surface of the body of water 54, into which the pan 68 drains.

It is furthermore to be noted that the suction nozzle formed by the lower end 58 of the bottom fitting 16.3 of Figure 6 is, in Figure 7, replaced by a footpiece or suction nozzle 69. The footpiece/suction nozzle 69 is described in more detail !0 hereunder with reference to Figures 10 and 11.

When the sieve or screen 66, the pan 68 and the associated bend or elbow 62 are omitted, water leaving the top of the stack along the pipe 24 from the bend or elbow connected to the fitting 16.5 at the top of the stack, merely passes

.5 along the full length of the pipe 24 to its end remote from the stack, for downstream particle separation and processing (instead of processing by the sieve or screen 66 adjacent the stack).

Turning to Figure 8, a pipe length for the fittings 16.4 and 16.5 is generally designated 36.3. The pipe length 36.3 has four equally circumferentially spaced fins 70 extending axially along its length and projecting radially outwardly from its outer curved surface. Each of the fins 70 is provided with a series of breaks or gaps 72 along its length, whereby it is interrupted.

In Figure 9, the end of the associated fitting, 16.4 or 16.5 as the case may be, is shown, with its shell 40.3 provided with a connecting flange 74 at each end thereof, the flange 74 having a ring of bolt holes 76, no inlet 42.5 being shown. The inner surface of the shell 40.3 is provided with four circumferentially spaced radially inwardly facing grooves 78, each groove 78 receiving and holding one of the fins 70 of the pipe length 36.3, to prevent rotation of the pipe length 36.3 in the shell 40.3 about its axis. The gaps 72 permit more or less unrestricted water flow into and out of all the parts of the interior of the shell 40.3 outside the pipe length 36.3, from the ends of the shell 40.3 and from one side of each fin 70, to the other. The nozzles 46 are arranged substantially as described above for Figures 2 - 4.

In Figures 10 and 11 the footpiece/suction nozzle 69, shown bolted to the lower end of the lowermost fitting 16.4 of the stack, and hereinafter referred to as the nozzle 69, is illustrated in more detail. The nozzle 69 has hollow right-cylindrical hollow tubular body 80, which is of the same inner diameter as, and forms a downward extension of, the pipe length 36.3 of the lowermost modular fitting 16.4. The upper end of the body 80 is provided with a circumferential flange 82 provided with bolt-holes 84 for bolting it via bolt holes 76 to the lower flange 74 of the lowermost fitting 16.4. The lower end of the body 80 is closed off by a disc 86 which has a central circular opening 88, of smaller diameter than that of the body 80. Two diametrically opposed limbs 90, connected to the lower surface of the flange 82 at opposite sides of the body 80, diverge away from each other in a downward direction, and have lower ends connected to a circular ring 92. The ring 92 is coaxial with the body 80 and disc 86, and is spaced downwardly therefrom, being parallel to the disc 86.

The opening 88 forms an inlet into the lower end of the body 80 and into the pipe length 36.3 of the lowermost fitting 16.4, and the ring 92 and limbs 90 together form a pedestal or stand whereby the lower end of the stack can rest on the bed 52 of gravel or grit, while holding the disc 86 and its opening 88 above the surface of the bed 52, to resist blocking of the opening 88 by gravel or grit in the bed 52.

In use water is drawn up the pipe 60 by the pump 12 and then pumped along the pipe 22 into the fitting 16.5 at the top of the stack, which it enters via the inlet 42.5. Water from the pump 22 flows lengthwise along the fittings 16.5 and 16.4 of the stack in their manifolds 38.1 and flows inwardly from their shells 40.3 into their pipe lengths 36.3 via their nozzles 46.

The nozzles 46 are directed to inject jets of water upwardly into the pipe lengths 36.3 so that an upward flow of water is created in the pipe lengths 36.3 of the fittings 16.4, 16.5 of the stack, which flow of water also moves helically as it moves upwardly. This movement causes a suction or reduced pressure at the inlet opening 88 through the disc 86 into the body 80 of the nozzle 69, relative to the surrounding water pressure at that depth, so that water, gravel and grit are sucked into the nozzle 69 and upwardly from the bed 52 into the stack. Water with entrained gravel and grit issues from the stack via the elbow or bend 62 at the top of the stack and into the first fitting 16.4 of the pipe 24. When the sieve or screen 66 and the pan 68 are provided, the water and gravel issue from the elbow or bend 62 at the opposite end of said first fitting 16.4, the sieve or screen 66 separating gravel or grit from water which drains via pan 68 into the body of water 54.

When the sieve or screen 66 and the pan 68 are omitted, water and entrained gravel or grit from the bend or elbow 62 at the top of the stack pass all the way along the full length of pipe 24, for downstream processing. In this case water from the pump 12 and pipe 22 flows via the leg of the T-piece into the inlet 42.5 of the f itting 16.5 forming part of t he p ipe 24, into the shell 40.3 of said f itting 16.5. Water from said shell 40.3 flows in opposite directions along the pipe 24 in the shells 40.3 of said various fittings 16.4. Water from the shells 40.3 of the fittings 16.4, 16.5 of the pipe 24 enters their pipe lengths 36.3 via their nozzles 46, thereby perpetuating the helical flow from the stack along the pipe 24. This flow, together with water entering the pipe lengths 36.3 of the various fittings 16.4, 16.5 of the pipe 24 from their shells 40.3 acts to maintain the entrainment of the grit or gravel in the water flowing along the pipe 24. It is to be noted that the problem addressed by the present invention is the unwanted settling of entrained particles being transported by the method and apparatus or installation. By imparting a helical flow to the fluid transporting the particles, enhanced reliability of entrainment is promoted and the wall or walls of the conduit are continually swept free of particles.

Claims

CLAIMS:

1. A method of transporting a particulate material along a conduit by means of a fluid by feeding a fluid containing particulate material entrained therein into and along the conduit in a desired downstream direction, while maintaining a sufficiently turbulent fluid flow in the conduit to prevent particles from settling from the fluid in the conduit, the method being characterized in that it comprises injecting a plurality of particle-free streams of said fluid in the form of jets through a wall of the conduit and into the particle-containing fluid flowing along the conduit, the jets being aligned in directions selected to cause the downstream flow of the particle-containing fluid along a h elical path, and t he i njecting of the fluid i nto the conduit b eing at a rate which maintains said entrainment of the particulate material in the fluid.

2. A method as claimed in Claim 1 , characterized in that the injecting of at least some of the streams is in the form of jets aligned in directions selected so that the jets cause helical flow of the particle-containing fluid in the conduit in the downstream direction along the conduit.

3. A method as claimed in Claim 1 or Claim 2, characterized in that the conduit is circular in cross-sectional outline, the injecting of at least some of the streams being effected at positions spaced both axially and circumferentially from one another and dispersed over the inner surface of the wall of the conduit.

4. A method as claimed in Claim 3, characterized in that the injecting of the streams is effected at positions spaced along a helical path extending along the inner surface of the wall of the conduit.

5. A method as claimed in any one of the preceding claims, characterized in that the injecting of each stream into the conduit takes place via a tubular injection nozzle projecting radially outwardly from the conduit, the nozzle having an outlet at the inner end t hereof, the inner end of the nozzle being flush with the inner surface of the conduit wall.

6. A method as claimed in any one of the preceding claims, characterized in that the injecting of at least some of the streams into the conduit is from a shell surrounding the conduit, fluid flow into the conduit taking place from an annular space defined between the conduit and the shell and fluid being fed under pressure from a source of particle-free fluid into the shell.

7. A method as claimed in any one of the preceding claims, characterized in that the particle-containing fluid is fed into a particle inlet at an open upstream end of the conduit, the feeding being by locating the upstream end of the conduit at or adjacent and spaced from particles to be entrained in the fluid, flow of fluid along the conduit arising from injection of the streams into the conduit giving rise to a pressure drop at said open upstream end from the exterior of the conduit to the interior of the conduit, which pressure drop causes flow of fluid into the open upstream end, the flow entraining particles in the fluid as it enters the conduit and the flow drawing the particles into the particle inlet of the conduit.

8. A method as claimed in Claim 7, characterized in that the inlet forms a lowermost extremity of the conduit, so that the conduit functions as a fluid lift for the particles, the transporting of the particles acting to raise them upwardly away from the particle inlet along the interior of the conduit.

9. A method as claimed in any one of Claims 1 - 6 inclusive, characterized in that the particle-containing fluid is fed into a particle inlet at an open upstream end of the conduit, the feeding being by withdrawal of particle-containing fluid from a volume of fluid which i s maintained in a state of turbulence whereby the particles therein are held in a suspended state.

10. A method as claimed in any one of the preceding claims, characterized in that the fluid is liquid water and the particulate material is gravel or grit, the method including pumping the water from a water supply to the conduit to provide the particle-free liquid which is injected into the conduit.

11. An apparatus or installation (10, 50) for the transportation of a particulate material entrained in a fluid in a desired downstream direction along a conduit in accordance with the method as claimed in Claim 1 , the apparatus for installation comprising a conduit (24) for leading a flow of particle-containing fluid from a particle inlet (58, 69) into the conduit to a particle outlet (18, 62) from the conduit, the apparatus or installation (10, 50) being characterized in that it is provided, through a wall of the conduit, with a plurality of fluid inlets (46) for injecting streams of said fluid in particle-free form as jets through the wall and into the conduit, the fluid inlets being located between the particle inlet and the particle outlet, and the fluid inlets being arranged to align the jets in directions selected to cause a downstream flow of particle-containing fluid along a helical path in the conduit and to permit fluid injection into the conduit at a rate which promotes entrainment of particles in the downstream fluid flow.

12. An apparatus or installation as claimed in Claim 11 , characterized in that the fluid inlets comprise passages arranged to inject the jets in directions which are aligned to have a downstream component in the direction of particle-containing fluid flow along the conduit, at least some of said passages being arranged to inject jets in directions which also have a tangential component, in the same circumferential direction, relative to said direction of particle-containing fluid flow along the conduit, for causing the helical flow of particle-containing fluid in the downstream direction.

13. An apparatus or installation as claimed in Claim 11 or Claim 12, characterized in that the conduit is circular in cross-sectional outline, the fluid inlets being located at positions spaced axially and circumferentially from one another and dispersed over at least a part of the inner surface of the wall of the conduit.

14. An apparatus or installation as claimed in Claim 13, characterized in that the fluid inlets are located at positions spaced along a helical path along the inner surface of the conduit.

15. An apparatus or installation as claimed in any one of Claims 11 - 14 inclusive, characterized in that each fluid inlet is defined by a tubular nozzle (46) projecting outwardly from the conduit, the nozzle having an inlet at its outer end and an outlet at the inner surface of a wall of the conduit, the outlet being flush with the inner surface of the wall so that the interior of the conduit is substantially free of any obstruction arising from the nozzle.

16. An apparatus or installation as claimed in any one of Claims 11 - 15 inclusive, characterized in that it includes at least one tubular shell (40, 40.1 , 40.2, 40.3) surrounding at least part (36, 36.1 , 36.2, 36.3) of the conduit (24), the fluid inlets into the conduit leading into the conduit from an annular space defined between the conduit and a said shell, at least one said shell being provided, intermediate its ends, with a fluid inlet (42, 42.1 , 42.2) for particle-free fluid under pressure.

17. An apparatus or installation as claimed in Claim 16, characterized in that the conduit is of composite construction, being made up of a series of modules (16, 16.1 , 16.2, 1 6.3, 1 6.4, 16.5) connected together end-to-end, each module comprising a length (36, 36.1 , 36.2, 36.3) of conduit provided with its own shell (40, 40.1 , 40.2, 40.3) and its own fluid inlets (46), at least one of the modules being provided with a fluid inlet (42, 42.1 , 4.2.2, 42.3, 42.4, 42.5) into its shell.

18. An apparatus or installation as claimed in Claim 17, characterized in that each module (16.4, 16.5) includes a plurality +of fins (70) extending along the length of the module, the fins (70) being equally circumferentially spaced around the associated length (36.3) of conduit and radiating therefrom to the associated shell (40.3), each fin having at least one gap (72) therein permitting fluid flow from one side of the fin to the other.

19. An apparatus or installation as claimed in any one of Claims 11 - 18 inclusive, characterized in that it includes a source of supply of particle-containing fluid in the form of a container (14) for holding therein particle-containing fluid having particles entrained therein, the particle inlet of the conduit being connected to an outlet from the container.

20. . An apparatus or installation as claimed in any one of Claims 11 - 18 inclusive, characterized in that it includes a suction nozzle (58, 69) forming the particle inlet of the conduit and connected to the conduit.

21. An apparatus or installation as claimed in any one of Claims 11 - 20 inclusive, characterized in that it includes a particle separation station (66, 68) at the downstream end of the conduit.

22. A fitting or sub-assembly (16, 16.1 , 16.2, 16.3, 16.4, 16.5) for forming part of an apparatus or installation (10, 50) as claimed in any one of Claims 11 - 21 inclusive, characterized in that it comprises a length (36, 36.1 , 36.2, 36.3) of conduit open at each end thereof, the conduit length being located in and connected to a tubular shell (40, 40.1 , 40.2, 40.3) which is concentric therewith, an annular space being defined between the conduit length and the shell, the fitting or sub-assembly having an annular connecting flange (44, 74) at each end thereof and including a plurality of fluid inlets (46) into the interior of the conduit length from said annular space for injecting streams of particle-free fluid as jets through the wall and into the conduit length, the fluid inlets being arranged to align the jets in directions selected to cause fluid flow in one direction along the conduit length and along a helical path.

23. A fitting or sub-assembly as claimed in Claim 22, characterized in that the fluid inlets comprise passages arranged to inject the jets in directions which have a longitudinal component relative to the length of conduit, at least some of said passages being arranged to inject jets in directions which also have a tangential component, in the same circumferential direction, for causing helical flow of fluid along the length of conduit.

24. A fitting or sub-assembly as claimed in Claim 22 or Claim 23, characterized in that the length of conduit is circular in cross-sectional outline, the fluid inlets being located at positions spaced axially and circumferentially from one another and dispersed over the inner surface of the wall of the conduit length.

25. A fitting or sub-assembly as claimed in any one of Claims 22 - 24 inclusive, characterized in that the fluid inlets are located at positions spaced along a helical path on the inner surface of the conduit length.

26. A fitting or sub-assembly as claimed in any one of Claims 22 - 25 inclusive, characterized in that each fluid inlet is defined by a tubular nozzle (46) projecting outwardly from the length of conduit, the nozzle having an inlet at its outer end in the interior of the shell and an outlet at the inner surface of a wall of the length of conduit, the outlet being flush with the inner surface of the conduit length wall so that the interior of the length of conduit is substantially free of any obstruction arising from the nozzle.

27. A fitting or sub-assembly (16.4, 16.5) as claimed in any one of Claims 22 - 26 inclusive, characterized in that it includes a plurality of fins (70) extending along the length (36.3) of conduit, the fins (70) being equally circumferentially spaced around the l ength of conduit and radiating therefrom to the s hell 40.3, each fin having at least one gap (72) therein permitting fluid flow from one side of the fin to the other.