Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
  • B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
  • B03B5/62—Washing granular, powdered or lumpy materials; Wet separating by hydraulic classifiers, e.g. of launder, tank, spiral or helical chute concentrator type
  • B03B5/626—Helical separators

Definitions

• This invention relates to spiral separators.
• Spiral separators are used extensively for the wet gravity separation of solids according to their specific gravities.
• spiral separators are used in separation of various kinds of mineral sands from silica sands, and in cleaning crushed coal by the removal of ash or other impurities.
• An example of such a spiral separator is described in pending Australian patent application No. 55205/80. Background Art
• Separators of the kind under discussion have a helical trough or sluice which has an inner wall and an outer wall connected by a floor.
• a pulp or slurry containing species to be separated is fed to the trough.
• the species in the slurry are sorted according to size and specific gravity with the largest and heaviest materials moving to one side of the stream and the finer and lighter materials being distributed in layers from the bed of the stream upwardly and from the
• OMPI inside of the curve outwardly and with water piling up on the outside of the bend.
• concentration band the largest and heaviest particles are concentrated in a band near the inner wall
• depleted band a band of depleted concentrate
• a splitter is arranged to remove the concentrate band via a take-off and the separation may be repeated on the depleted band. Disclosure of the Invention
• Methods according to the invention achieve the first object by the step of diverting the overlying depleted band or layer outwardly from the underlying concentrate at a location upstream of a concentrate take-off.
• a slurry deflector is situated inwardly of the depleted band.
• the shape of the deflector and the velocity of the slurry are selected so that a "bow wave" is produced which urges the overlying depleted band outwards.
• the deflection means serve to fan out the width of the concentrate band in addition to diverting the overlying depleted band outwards relative thereto, the widened concentrate band facilitating setting by an operator of take-off splitters to obtain optimum grade and/or yield of concentrate .
• an “outwardly” direction is a direction towards the outer wall of the trough and an “inwardly” direction is a direction towards the inner wall of the trough.
• the number of turns , pitch and floor angle of the spirals may be selected to suit the particular concentrate to be concentrated and the spirals may be provided with an inner gutter provided between the column and the inner wall , to receive and convey the concentrate taken out of the pulp at the various take-offs in the spiral.
• the take-offs may be of any suitable type , for example the type disclosed in Australian Patent No . 522, 914 having a transverse slot, or may include slots or discontinuities in the inner wall leading to the inner trough, and fixed or movable splitter blades may be provided to direct the concentrate through the take-offs .
• the deflection means are provided approximately 50-200 mm upstream of the take-of fs and they may be provided on any or all of the turns of the spiral . However it is preferred that they are provided on every second turn of the spiral to enable the pulp to
• the "deflection velocity” is the velocity at which it is observed that for example the silica sand (or gangue) is deflected outwardly from the inner wall of the spiral by a "bow wave” created by the deflection means.
• the deflection means may be fixed in, on or adjacent the inner wall of the spiral or may be movable relative thereto and the deflection means may be concealed in a recess formed in the inner wall to allow an unimpeded flow of the pulp down the spiral when not required.
• the deflection means may be spaced from the inner wall to allow the portion of the mineral flow to be umirapeded, the deflection means operating to deflect the gangue or silica from the outer portion of the mineral flow.
• the deflection means may include a blade, finger or other formation which extends upwardly from the floor, or which has a slot or aperture adjacent the floor which allows the band of concentrate to flow unimpeded down the spiral but where the overlying band or layer of silica is deflected outwardly.
• the invention consists in a spiral separator having a helical trough including an inner wall and an outer wall connected by a floor and having at least one take-off for a concentrate species separated from a depleted remainder, said separator including deflection means arranged so that a band depleted remainder which in use of the separator at least partially overlies a concentrate band is diverted in an outward direction relative to the concentrate species.
• the invention consists in a method for separating a first species from a second species having a specific gravity different from the first species comprising the steps of:
• the invention consists in a method of re-mixing a slurry of solids in water flowing down a spiral separator with water which has become separated from the slurry due to centrifugal force, the method comprising the steps of: causing the slurry to flow through a passage of restricted width between the inner and the outer wall, and deflecting said water which has become separated inwardly into the restricted passage.
• the restricted passage is defined between the spiral outer wall and an outwardly deflecting formation provided as a continuation of the inner wall of the spiral.
• the outer wall is provided with an inwardly deflecting formation formed integrally with the outer wall.
• a roof may be provided over the restricted passage to prevent the water being splashed or deflected out of the spiral, and the roof may have downwardly directed leading and/or tailing edges to deflect the water downwardly into the passage of restricted width to increase the remixing or repulping of the water and the tailings.
• FIG. 1 is a plan view of one turn of a first embodiment of a separator spiral according to the invention.
• FIGS. 2, 3, 4 and 5 are respective sectional side views taken on lines 2-2, 3-3, 4-4 and 5-5 on FIG. 1.
• FIG. 6 is a plan view showing part of one turn of a second embodiment according to the invention. Description of Preferred Embodiment
• the spiral assembly 10 has four similar spirals provided around a substantially vertical central column 11, the upper ends of the spirals being connected to a
• the separator is used to separate a mineral concentrate from a silica sand.
• Each spiral 12 has an outer wall 13 connected to a spiral floor 14 which is inclined to the horizontal.
• the inner wall 15 is fixed to the column 11 and thereafter is spaced from the column by a gutter 16 adapted to convey the separated concentrate to a concentrate outlet (not shown) at the bottom of the spiral.
• the spirals 12 are preferably formed of fibreglass.
• a take-off 17, having a transverse slot 18 and movable splitter blade 19, of the type disclosed in Australian Patent No. 522,914, is provided to convey the concentrate separated from the pulp to the gutter 16, the steep angle of the gutter to the horizontal ensuring that the concentrate will flow freely down the gutter.
• a deflector 20, approximately 15-20mm wide, is provided integrally with the inner wall 15 approximately 50-200 mm upstream of the take-off 17. As shown in FIG. 1, the nose of the deflector is rounded to enable the concentrate 21a to flow around the deflector 20 with a relatively smooth flow. However, the deflector 20 creates a "bow wave" in the water containing the silica sand layer partially overlying the concentrate 21a and this "bow wave” diverts the silica outwardly, away from the inner wall, to leave a clean, albeit wider, band of concentrate 21a. (The width of the concentrate band may be increased to e.g. 25mm downstream of the deflector 20, from a width of e.g. 15mm upstream of the deflector 20).
• the operator by observing the concentrate band, can adjust the splitter blade 19 to take almost all the concentrate 21a.
• the wider band of concentrate, free of the silica sand, enables an initial cut ' of higher grade and yield to be taken than with a conventional spiral.
• FIG. 6 there is shown schematically a second embodiment in which a first deflector blade 30 is mounted by means of a pin 31 so that the angle of the blade to the direction of -flow of slurry is adjustable.
• Inner wall 15 is provided with a recess whereby blade 30 can be moved out of the stream when not in use. If desired, the height of the lower edge of blade 30 above the trough floor may be made adjustable.
• the concentrate band in Figure 6 lies radially inwards of line 32 it being understood that in practice the concentrate band and depleted band are not separated by a line.
• Flow lines 33 and 34 show a bow wave in the vicinity of blade 30.
• a repulping assembly 21 is provided just downstream of take-off 17.
• Second deflector 22, which is crescent-shaped in plan, is formed by diverting the inner wall 15 of the spiral outwardly in a smooth curve and then returning it to its initial path to form a restricted width passage 23.
• the inner wall 15 is connected to a gutter outer wall 24 by a connecting panel 25.
• Third deflector 26 is provided integrally with the outer wall 13 just downstream of the take-off 17 and may be of similar width to first deflector 20.
• concentrate is removed via take-off 17.
• Water moves to the outer wall 13 of the spiral under centrifugal force, while the unseparated remainder comprising tailings and any concentrate remaining in the pulp continue past the take-off 17 adjacent the inner wall 15.
• the water strikes or impinges against third deflector 26 and is directed inwardly and upwardly against the roof section 27.
• the tailings and remaining concentrate are moved outwardly by the second deflector 22, and so are caused to be remixed, or repulped, with the water.
• the leading or trailing edges 28 of the roof section direct any water striking the latter downwardly to assist in this mixing process.
• the pitch of the spiral over a short section of the restricted passage 24 may be increased to accelerate the tailings and remaining concentrate to further assist in the mixing process.
• the remaining concentrate begins to separate from the tailings and may be taken off into the gutter 16 by a second take-off 17 provided at e.g. the fourth turn, the tailings continuing to a middling and/or tailings outlet (or outlets) at the bottom of the spiral. (These outlets may be of the type disclosed in pending Application No. 55205/80).
• a deflector similar to deflector 20 may be provided upstream of the second take-off.
• a further deflector, provided e.g. on the third turn of the spiral, may be required to retard the flow of the concentrate down the third and fourth turns of the spiral, otherwise the concentrate reaches a velocity which is such that the centrifugal force on the concentrate moves it outwardly into or over the tailings layer.
• spirals are compact, and do not require any additional wash water fittings, and because the repulping assembly ensures the flow of the pulp down the spirals, up to four spirals may be mounted on each column 11.
• deflectors 20, take-offs 17 and repulping assemblies 21 can be provided on any or all of the spiral turns.
• the pulp must preferably reach a "deflection velocity" where the "bow wave” effect is created to deflect the silica or other gangue, and so generally the first deflector 20 will be provided on the second turn and any subsequent similar deflectors or take-offs approximately every l -2 turns thereafter, with retardingdeflectors (if necessary) to control the upper limit of the pulp velocity intermediate the take-offs.
• the gangue or silica only overlies the outer portion of the concentrate.
• the first deflector 20 (and subsequent deflectors) may be spaced inwardly from the inner wall to provide an undisturbed path for the inner portion of the concentrate.
• the outer portion is deflected, as hereinbefore described, but the mineral flows inwardly to fill the void downstream of the deflector as the gangue or silica is deflected outwardly to produce a clear stream of mineral concentrate downstream of the deflector.
• the deflector may be movable across spiral to suit the particular mineral being separated from the pulp.
• a vane shaped deflector may be used and this may be pivotally mounted.
• the size, shape and position of the repulping assemblies will be dictated by the nature of the pulp to be separated and the pitch of the spirals. It will be readily apparent that the design of the repulping assembly will preferably ensure a good flow of the pulp down the spiral to eanble high feed rates to be fed to the spirals, while ensuring adequate repulping of the water and tailings to ensure continuity of flow of same down the spirals, with as little disturbance of the partially separated concentrate as is possible. In certain applications, e.g. the separation of high grade mineral at lower feed rates, it may be preferred to allow a portion of the wash water to flow over the second deflector 26 to prevent excessive turbulence being generated in the repulping assemblies.
• the deflector may extend up only a portion of the height of the outer wall 13.
• the height of the deflector may be made adjustable.
• the deflector may have a fixed lower portion formed integrally with the wall and an inner, telescopic portion, which may be raised or lowered to adjust the height operated by a suitable control stick, rod or bar.
• the present invention of repulping with the water contained in the initial feed is substantially costless and operator free.

Landscapes

• Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
• Physical Water Treatments (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Cell Separators (AREA)
• Cyclones (AREA)
• Combined Means For Separation Of Solids (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Paper (AREA)

Applications Claiming Priority (4)

Publications (3)

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Family Applications (1)

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• 1984
  • 1984-04-05 NZ NZ207756A patent/NZ207756A/en unknown
  • 1984-04-10 MX MX017195A patent/MX172433B/es unknown
  • 1984-04-10 IN IN316/DEL/84A patent/IN159817B/en unknown
  • 1984-04-11 PH PH30533A patent/PH21494A/en unknown
  • 1984-04-11 EG EG223/84A patent/EG16227A/xx active
  • 1984-04-12 CA CA000451829A patent/CA1237697A/fr not_active Expired
  • 1984-04-12 WO PCT/AU1984/000058 patent/WO1984004058A1/fr active IP Right Grant
  • 1984-04-12 JP JP59501521A patent/JPH0622699B2/ja not_active Expired - Lifetime
  • 1984-04-12 RO RO116625A patent/RO92498B/ro unknown
  • 1984-04-12 EP EP84901310A patent/EP0141822B1/fr not_active Expired
  • 1984-04-12 BR BR8406596A patent/BR8406596A/pt not_active IP Right Cessation
  • 1984-04-13 ES ES84531614A patent/ES8507013A1/es not_active Expired
• 1987
  • 1987-09-30 MY MYPI87002506A patent/MY102182A/en unknown

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