WO2001072426A1 - Dewatering apparatus - Google Patents

Dewatering apparatus Download PDF

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Publication number
WO2001072426A1
WO2001072426A1 PCT/IE2001/000043 IE0100043W WO0172426A1 WO 2001072426 A1 WO2001072426 A1 WO 2001072426A1 IE 0100043 W IE0100043 W IE 0100043W WO 0172426 A1 WO0172426 A1 WO 0172426A1
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WO
WIPO (PCT)
Prior art keywords
sand
hollow interior
interior region
slurry
housing
Prior art date
Application number
PCT/IE2001/000043
Other languages
French (fr)
Inventor
John Peter Bielenberg
Original Assignee
John Peter Bielenberg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by John Peter Bielenberg filed Critical John Peter Bielenberg
Priority to AU2001242710A priority Critical patent/AU2001242710A1/en
Publication of WO2001072426A1 publication Critical patent/WO2001072426A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
    • C02F11/126—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using drum filters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/06—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
    • B01D33/11—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for outward flow filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/44—Regenerating the filter material in the filter
    • B01D33/46—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
    • B01D33/466—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element scrapers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
    • B01D33/76—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging the filter cake, e.g. chutes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/80—Accessories
    • B01D33/801—Driving means, shaft packing systems or the like
    • 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
    • B03B5/48—Washing granular, powdered or lumpy materials; Wet separating by mechanical classifiers
    • B03B5/56—Drum classifiers

Definitions

  • the present invention relates to apparatus for dewatering sand in a slurry suspension of sand and other solids which are of lower density size to that of the sand.
  • Such solids typically are soil, clay, and other organic particulate material which is typically found in sand and gravel pits.
  • Sand when quarried typically comprises other solid matter, such as soil, clay and other organic matter.
  • the sand must be separated from all such non-sand matter, and this typically is carried out by a washing process whereby the non-sand matter is washed from the sand.
  • water is added to the sand and non-sand matter to form a slurry.
  • dewatering processes Using various separating techniques which generally are referred to as dewatering processes, the sand is initially separated from the non-sand matter, and then the water and sand are separated from each other.
  • Such dewatering processes tend to be relatively complex and expensive to install. Additionally, many known dewatering apparatus tend to be inefficient, in that sand may be lost in the dewatering process, or alternatively soil and other fine particulate matter may be carried with the sand. This is undesirable.
  • such known apparatus comprises a settling tank into which the slurry of sand and other solids, namely, non-sand matter is continuously delivered.
  • the sand settles out of the slurry to the base of the tank, and the slurry with the non-sand matter flows from the tank over a weir.
  • a transfer mechanism which may be provided by a plurality of transfer buckets which are located around the periphery of a rotatably mounted transfer framework, collects the sand which has settled to the base of the tank and transfers it upwardly for delivery into a chute.
  • the buckets are perforated for facilitating dewatering of the sand as it is being transferred upwardly from the tank to the chute.
  • a particular disadvantage of this type of apparatus is that the entire base of the tank is not swept by the transfer mechanism, and thus other mechanisms are required for urging the settled sand in the tank towards the transfer mechanism. Such mechanisms for urging the sand towards the transfer mechanism tend to cause turbulence in the slurry which inhibits settling of the sand, thereby leading to loss of significant volumes of sand which flow with the slurry from the tank.
  • the present invention is directed towards providing such a dewatering apparatus.
  • apparatus for dewatering sand in a slurry suspension of sand and other solids, the other solids being of lower density to that of the sand wherein the apparatus comprises a housing defining a geometric central axis and a hollow interior region extending axially between a pair of spaced apart axially opposite end walls, and being rotatably mounted about its central axis, a delivery means for delivering the slurry into the hollow interior region through one of the end walls, a discharge means for discharging dewatered sand from the hollow interior region through one of the end walls, a transfer means located in the hollow interior region for transferring sand to the discharge means as the housing is rotating and for dewatering the sand as the sand is being transferred to the discharge means, an outlet from the hollow interior region extending through one of the end walls through which slurry residue with the solids of lower density to that of the sand suspended therein is discharged from the hollow interior region, and a main drive means for
  • the outlet and the delivery means extend through the same end wall.
  • the end wall of the two end walls through which the outlet extends is different to the end wall through which the delivery means extends.
  • the discharge means and the delivery means extend through the same end wall.
  • the end wall of the two end walls through which the discharge means extends is different to the end wall through which the delivery means extends.
  • the delivery means extends into the hollow interior region, and terminates in a delivery port which is located relative to the outlet for delivering the slurry into the hollow interior region so that the slurry flows axially from the delivery port to the outlet for facilitating precipitation of the sand out of suspension in the slurry in the hollow interior region for collection by the transfer means.
  • the delivery means and the outlet are located relative to each other so that as the slurry flows through the hollow interior region from the delivery means to the outlet with the sand precipitating out of suspension in the slurry in progressively reducing grade size from the delivery means to the outlet.
  • the slurry is delivered into the hollow interior region by the delivery means so that the solids of lower density to that of the sand remain entrained in the slurry in the hollow interior region at a level above that at which the sand is collected by the transfer means.
  • the delivery means delivers the slurry into the hollow interior region such that the sand precipitates downwardly out of suspension in the slurry so that the precipitating sand is graded by size in an axial direction across the hollow interior region.
  • the sand of largest grade is located in the hollow interior region towards one end wall of the housing, and the grade reduces progressively in an axial direction towards the other end wall.
  • a pair of discharge means is provided, the respective discharge means extending through the respective end walls of the housing.
  • the respective discharge means are located within the hollow interior region so that sand of larger grade is transferred by the transfer means onto one of the discharge means, than onto the other of the discharge means.
  • the respective positions of the respective discharge means are axially variable within the hollow interior region for varying the grade size of sand transferred onto the respective discharge means by the transfer means.
  • each discharge means comprises a chute extending from a hopper located in the hollow interior region.
  • each discharge means comprises a discharge conveyor extending from within the hollow interior region.
  • each discharge conveyor is provided by an endless conveyor belt.
  • a carrier means extends through the housing parallel to the central axis thereof for carrying each discharge means.
  • each discharge means is slideably carried on the carrier means for axially adjusting the position of each discharge means for varying the grade of sand transferred onto the respective discharge means from the transfer means.
  • a guide means is located within the hollow interior region for guiding the sand being transferred by the transfer means onto the corresponding discharge means.
  • a communicating opening is provided in each end wall through which any one of the delivery means, the discharge means or the outlet extends therethrough for accommodating the respective delivery means, discharge means or outlet.
  • each end wall communicating opening is coaxial with the central axis of the housing.
  • the communicating opening in one of the end walls defines the outlet.
  • the communicating opening which defines the outlet defines a circumferential periphery which forms a weir over which slurry residue passes for retaining the slurry at a predetermined level within the hollow interior region.
  • an outwardly diverging lip extends from and around the communicating opening which defines the outlet for directing the sludge residue into a collecting means.
  • the delivery means comprises a delivery pipe extending into the hollow interior region through the corresponding communicating opening.
  • the central axis of the housing is substantially horizontal.
  • the transfer means collects the sand at a lower portion of the hollow interior region and transfers the sand to an upper portion of the hollow interior region for transferring the sand onto the discharge means.
  • the sand is transferred from the transfer means to the discharge means under gravity.
  • the lower portion of the housing at which the sand is collected by the transfer means is below the central axis, and the upper portion of the housing from which the sand is transferred from the transfer means to the discharge means is above the central axis.
  • the transfer means is perforated for straining the sand and for draining the liquid slurry from the sand in the transfer means.
  • the grade of the perforations in the transfer means is such as to retain the sand therein but to permit passage of at least most of the solids of lower density and smaller particle size to that of the sand therethrough.
  • each transfer means comprises a plurality of transfer panels which extend axially within the hollow interior region for collecting the sand as the housing rotates.
  • each transfer panel extends between and engages the respective opposite end walls of the housing.
  • each transfer panel co-operates with the housing for retaining the sand thereon as the sand is being transferred to the discharge means.
  • each transfer panel extends in a generally inwardly radial, circumferential direction in the direction of rotation of the housing.
  • each transfer panel terminates in an axially extending edge at a position spaced apart from the outlet so that solids entrained in the slurry are not engaged by the transfer means as the housing rotates.
  • each transfer panel is of a mesh material, and advantageously, the transfer panels are equi-spaced circumferentially around the central axis.
  • the transfer means is formed by an inner surface of the housing, and a dislodging means co-operating with the inner surface of the housing is provided for dislodging the sand from the inner surface for transfer to the discharge means.
  • the dislodging means is located within the hollow interior region above the discharge means.
  • the housing comprises a cylindrical wall extending between the respective end walls, and each transfer means extends from the cylindrical wall in a generally radial, circumferential direction in the direction of rotation of the housing.
  • the housing is carried on a pair of spaced apart rollers extending parallel to the central axis, one of the rollers being driven by the main drive means.
  • the other of the two rollers is an idler roller.
  • each roller is flanged at respective opposite ends for retaining the housing in position on the respective rollers.
  • the housing is rotated by the main drive means at a speed which permits the sand to precipitate from the slurry for collection by the transfer means, but which is sufficient for maintaining the solids of density lower than the sand entrained in suspension in the slurry.
  • the housing is rotated at 1 a speed in the range of « rpm to 2 rpm.
  • the housing is rotated at a speed in the range of 1 / 2 rpm to 1 Yz rpm.
  • the housing is rotated at a speed of approximately 1 rpm.
  • the apparatus for dewatering sand according to the invention is a particularly efficient dewatering apparatus. It has been found in general that little or no sand is lost with the slurry residue which flows through the outlet from the hollow interior region of the housing. This is largely because turbulence in the slurry within the hollow interior region is minimised, thereby permitting virtually all of the sand particles to settle out of the slurry.
  • the rotational speed of the housing can be maintained at a speed which minimises turbulence.
  • a further advantage of the invention is achieved when the apparatus is provided with a pair of discharge means, the axial positions of which can be varied for varying the particle size of the sand discharged by the respective discharge means.
  • Fig. 1 is a front end elevational view of apparatus according to the invention for dewatering sand in a slurry suspension of sand and other solids
  • Fig. 2 is a partly cut away, partly cross-sectional front end elevational view of the apparatus of Fig. 1
  • Fig. 3 is a partly cut away, partly cross-sectional side elevational view of the apparatus of Fig. 1 ,
  • Fig. 4 is a partly cut away, partly cross-sectional top plan view of the apparatus of Fig. 1 ,
  • Fig. 5 is a rear end elevational view of a portion of the apparatus of Fig. 1 ,
  • Fig. 6 is a partly cut away, partly cross-sectional rear end elevational view of apparatus according to another embodiment of the invention also for dewatering sand in a slurry suspension of sand and other solids,
  • Fig. 7 is a partly cut away, partly cross-sectional side elevational view of the apparatus of Fig. 6,
  • Fig. 8 is a top plan view of the apparatus of Fig. 6,
  • Fig. 9 is a partly cut away, partly cross-sectional front end elevational view of a portion of apparatus according to a further embodiment of the invention also for dewatering sand in a slurry suspension of sand and other solids,
  • Fig. 10 is a partly cut away, partly cross-sectional side elevational view of the portion of the apparatus of Fig. 9,
  • Fig. 11 is a partly cut away, partly cross-sectional rear end elevational view of the portion of the apparatus of Fig. 9, and
  • Fig. 12 is a cross-sectional end elevational view of a detail of the apparatus of Fig. 9.
  • dewatering apparatus for separating sand out of a slurry suspension of sand and other solids and for dewatering the sand, the other solids being of lower density to that of the sand.
  • the apparatus 1 comprises a housing, in this embodiment of the invention provided by a cylindrical drum 2 which is rotatably carried on a base framework 3 by a pair of spaced apart parallel rollers, namely, a drive roller 5 and an idler roller 6.
  • Bearings 8 rotatably support the drive and idler rollers 5 and 6 on the base framework 3 parallel to each other and parallel to a central geometric axis 10 of the drum 2 about which the drum 2 is rotatable.
  • a main drive means comprising a main drive motor 12 mounted on the base framework 3 drives the drive roller 5 for rotating the drum 2 about the central axis 10 in the direction of the arrow A during the separating and dewatering process, as will be described below.
  • the cylindrical drum 2 comprises a cylindrical circumferentially extending side wall 15 which extends between a pair of axially opposite spaced apart end walls 16 and 17 which together with the side wall 15 define a hollow interior region 18 into which the slurry is delivered.
  • a pair of communicating openings 20 and 21 are provided in the end walls 16 and 17 for providing access and egress to and from the hollow interior region 18.
  • the openings 20 and 21 are centrally located in the end walls 16 and 17 and are co-axial with the central axis 10, the diameter of the communicating opening 21 being greater than that of the communicating opening 20.
  • a delivery means provided by a delivery pipe 24 delivers the slurry of water, of sand and other solids into the hollow interior region 18.
  • the delivery pipe 24 extends through the communicating opening 20 in the end wall 16 and terminates in a delivery port 25 through which the slurry is delivered into the hollow interior region 18.
  • the communicating opening 21 in the end wall 17 forms an outlet 27 from the hollow interior region 18 through which a slurry residue of water and non-sand solids entrained in the slurry residue is delivered from the hollow interior region 18.
  • the communicating opening 21 defines a circumferentially extending peripheral edge 28 which forms a weir over which the slurry residue flows from the hollow interior region 18 into a collecting means, namely, a collecting sump 29.
  • An outwardly diverging lip 30 extends around and outwardly from the circumferential edge 28 of the communicating opening 21 for directing the slurry residue from the outlet 27 into the collecting sump 29. Since the diameter of the opening 21 is greater than that of the opening 20, the peripheral edge 28 which forms the weir as the drum 2 is rotating determines the level at which the slurry is retained in the hollow interior region 18, and thus retains the slurry in the hollow interior region 18 at a predetermined level.
  • the delivery port 25 is located in the hollow interior region 18 at a level which is just above the level at which the slurry is retained in the hollow interior region 18 by the outlet 27 and relatively close to the end wall 16, so that the slurry flows in an axial direction across the drum 2 from the delivery port 21 adjacent the end wall 16 to the outlet 27 in the end wall 17. Because the slurry flows in a direction from the end wall 16 to the end wall 17, the smaller grade sand particles are carried in suspension towards the outlet 27 and progressively precipitate downwardly out of suspension into a lower portion 32 of the drum 2, the smallest grade particles being carried the greatest distance towards the end wall 17. The largest grade particles because of their weight fall almost directly from the delivery port 25 downwardly to settle in the lower portion 32 of the drum 2.
  • the sand precipitates downwardly out of suspension into the lower portion 32 of the drum 2 with the sand grade becoming progressively smaller from the largest grade to the smallest grade from the end wall 16 to the end wall 17, respectively.
  • the drum 2 is rotated at a speed, which in this embodiment of the invention is approximately 1 rpm, which is just sufficient to maintain the solids of lower density to that of the sand in suspension above the lower level 32 at which the sand settles downwardly in the drum 2, while at the same time the rotational speed of the drum is sufficiently slow to permit the sand to precipitate downwardly out of suspension within the hollow interior region 18.
  • a plurality of transfer means comprising a plurality of transfer panels 35 extending between the end walls 16 and 17 and from the cylindrical side wall 15 collect the sand which is precipitating downwardly in the lower portion 32 as the drum 2 is rotating, and transfer the collected sand upwardly from the lower portion 32 to an upper portion 36.
  • the transfer panels 35 sequentially reach the upper portion 36 the sand falls under gravity onto a pair of discharge means, namely, a pair of discharge conveyors 38 and 39 which extend through the respective communicating openings 20 and 21 , respectively, for discharging dewatered sand from the hollow interior region 18.
  • the transfer panels 35 are of perforated mesh material having an appropriate mesh size such as to retain sand of particles above a predetermined minimum particle size, while permitting the water and any other solids of lesser particulate size to pass therethrough. Typically, the mesh size would range between 1mm and 6mm.
  • the transfer panels 35 are equi-spaced circumferentially around and extend from the cylindrical side wall 15 in a generally radial, circumferential direction and in a circumferential direction in the direction of rotation of the drum 2, and thus, co-operate with the cylindrical side wall 15 for retaining the sand collected in the lower portion 32 of the hollow interior region 18 until the transfer panels 35 reach the upper portion 36 of the hollow interior region 18.
  • Each transfer panel 35 extends from the cylindrical side wall 15 and terminates in an axially extending edge 37 at a position spaced apart from outlet 27 so that as the drum 2 rotates the transfer panels 35 clear the solids entrained in the slurry flowing between the delivery port 25 and the outlet 27.
  • Each discharge conveyor 38 and 39 comprises an endless conveyor belt 40 which extends between and is carried on a corresponding pair of carrier rollers 41.
  • the carrier rollers 41 extend between and are rotatably carried in a pair of spaced apart side support members 42.
  • a secondary drive means namely, a pair of secondary drive motors (not shown) mounted on one of the side support members 42 each drive a corresponding one of the carrier rollers 41 of each discharge conveyor 38 and 39 for driving the respective endless conveyor belts 40 in the directions of the arrows C and D for discharging the sand from the hollow interior region 18.
  • a carrier means provided by a pair of spaced apart parallel carrier tracks 45 of channel construction extend through the hollow interior region 18 and through the communicating openings 20 and 21 for slideably carrying the respective discharge conveyors 38 and 39 axially through the hollow interior region 18.
  • Upstanding supports 46 extending upwardly from the base framework 3 support the carrier tracks 45.
  • Two bearing rollers 44 rotatably carried on and extending sidewardly from each side support member 42 rollably engage a lower web 47 of the adjacent carrier track 45 for facilitating axial sliding of the discharge conveyors 38 and 39 along the carrier tracks 45.
  • a guide means provided by a pair of spaced apart inclined main guide plates 48 located within the hollow interior region 18 and supported on support stays 49 which extend upwardly from the carrier tracks 45 guide sand falling under gravity from the transfer panels 35 onto the respective discharge conveyors 38 and 39.
  • a pair of secondary guide plates 50 which are carried on a support bracket 52 extending upwardly from the respective side support members 42 of the discharge conveyors 38 and 39 guide the sand falling under gravity from the transfer panels 35 onto the discharge conveyors 38 and 39 at the respective ends thereof within the hollow interior region 18.
  • the maximum grade size of sand collected on the discharge conveyor 39 can be varied, while the minimum grade size of sand collected on the discharge conveyor 38 can also be varied.
  • the maximum grade size of sand collected on the discharge conveyor 39 is increased, while the minimum grade size of sand collected on the discharge conveyor 18 is also increased.
  • Sliding the discharge conveyors 38 and 39 in the direction of the arrows F decreases the minimum grade size of sand which is collected on the discharge conveyor 38, and also decreases the maximum grade size of sand which is collected on the discharge conveyor 39. This is by virtue of the fact that the grade size of sand which precipitates out of the slurry in the lower portion 32 of the hollow interior region 18 progressively decreases from the end wall 16 to the end wall 17.
  • a sump outlet 54 from the collecting sump 29 is provided for discharging the slurry residue which collects in the collecting sump 29 for further treatment.
  • the drive and idler rollers 5 and 6 each comprise a drive shaft 55 which is rotatably carried in the bearings 8, and respective roller portions 56 for rollably carrying the drum 2. End flanges 57 extending around the roller portions 56 locate and retain the drum 2 on the respective rollers 5 and 6 during rotation.
  • a slurry of water with sand and other solid matter in suspension from which the sand is to be separated is delivered through the delivery pipe 24 into the hollow interior region 18.
  • the sand commences to precipitate out and downwardly of the slurry into the lower portion 32 with the grade of sand progressively reducing from the end wall 16 to the end wall 17.
  • the sand precipitating out of the slurry in the lower portion 32 is collected by the transfer panels 35 and transferred onto the respective discharge conveyors 38 and 39 as the drum 2 rotates.
  • As the transfer panels 35 pass out of the slurry any slurry of water and other solids of particle size less than the mesh size remaining on the transfer panels 35 drain through the perforations of the transfer panels 35, thereby leaving dewatered sand to be transferred onto the discharge conveyors 38 and 39.
  • the respective positions of the discharge conveyors 38 and 39 are selected so that sand of the desired grades is collected on the respective discharge conveyors 38 and 39 and discharged out of the hollow interior region 18 in the direction of the arrows C and D.
  • FIG. 6 to 8 there is illustrated apparatus according to another embodiment of the invention, which is indicated generally by the reference numeral 60, also for separating sand from a slurry of sand and other solids in suspension of lower density to that of the sand.
  • the apparatus 60 is substantially similar to the apparatus 1 and similar components are identified by the same reference numerals.
  • the main difference between the apparatus 60 and the apparatus 1 is that only the end wall 17 is provided with a communicating opening 21. No communicating opening is provided in the end wall 16.
  • the communicating opening 21 also forms the outlet 27, but as well as that accommodates the delivery pipe 24 into the hollow interior region 18.
  • the discharge means is provided by a discharge chute 62 which inclines downwardly through the communicating opening 21 and extends from a hopper 63 located within the hollow interior region 18 for collecting sand delivered under gravity from the transfer panels 35.
  • the delivery pipe 24 extends inwardly into the hollow interior region 18 and terminates in the delivery port 25 adjacent the end wall 16 for providing axial flow of the slurry from the delivery port 25 to the outlet 27 for facilitating precipitation of the sand downwardly out of suspension as the slurry flow axially from the delivery port 25 to the outlet 27.
  • only one single chute 62 is provided from the hollow interior region 18, the sand is delivered from the hollow interior region 18 ungraded.
  • FIGs. 9 to 12 there is illustrated apparatus according to another embodiment of the invention indicated generally by the reference numeral 70 for dewatering sand in a slurry suspension of sand and other solids.
  • the apparatus 70 is particularly suitable for dewatering particularly fine sand of the type typically referred to as microfine or superfine sand, which typically, would be of maximum particle size not exceeding Vz mm.
  • the apparatus 70 is substantially similar to the apparatus 1 described with reference to Figs. 1 to 5, and similar components are identified by the same reference numerals.
  • the apparatus 1 is provided with only one single discharge conveyor 38, and secondly, in this embodiment of the invention the transfer means instead of being provided by transfer panels 35 is provided by an inner surface 71 of the cylindrical side wall 15 of the drum 2.
  • the discharge conveyor 38 is carried directly on the upstanding supports 56 and is not moveable axially within the hollow interior region 18 of the drum 2.
  • the apparatus 70 is specifically suitable for dewatering microfine and superfine sand, it has been found that the wet sand particles because of their size and weight adhere to the inner surface 71 of the cylindrical side wall 15 by surface tension.
  • the inner surface 71 picks up the sand particles in the lower portion 32 of the hollow interior region 18, and the particles are transferred upwardly out of the slurry into the upper portion 36 of the hollow interior region 18 of the drum 2 on the inner surface 71 of the cylindrical side wall 15, as the drum 2 rotates in the direction of the arrow A.
  • a dislodging means for dislodging the sand particles from the inner surface 71 of the side wall 15 comprises a scraper 73 which is carried on a support member 74 extending upwardly from one of the side support members 42 of the discharge conveyor 38.
  • the scraper 73 is of resilient flexible plastics material and is secured in a mounting bracket 75 mounted on the support member 74.
  • the scraper 73 extends axially across the hollow interior region 18 between the respective end walls 16 and 17 for scraping the entire inner surface 71 of the side wall 15 across its axial width.
  • the main guide plate 48 is carried on the support member 74.
  • the diameter of the outlet 27 is considerably greater than the outlets 27 of the apparatus 1 and 60. This is because in this embodiment of the invention the transfer plates are omitted, and thus there is no need to maintain the level of water in the hollow interior region at a level well above the axial edges 37 of the transfer plates when extending upwardly from the bottom of the drum, and furthermore, it has been found desirable to maintain the level of the water in the drum relatively shallow when dewatering sand of microfine and superfine particle size.
  • the apparatus 70 is substantially similar to the apparatus 1 , and its operation is likewise similar, the only significant difference being that as the drum 2 rotates in the direction of the arrow A, the sand particles adhere by surface tension to the inner surface 71 and are transferred by the inner surface 71 as the drum 2 rotates from the lower portion 32 to the upper portion 36 of the drum, at which stage they are scraped from the inner surface 71 by the scraper 73.
  • the main guide plate 48 collects the sand particles falling from the inner surface 71 , and directs the sand particles onto the discharge conveyor 38.
  • the sand particles are discharged by the discharge conveyor, either through the opening 20 in the end wall 16 or through the opening 21 in the end wall 17
  • the discharge means has been provided by a pair of discharge conveyors, it will be appreciated that in certain cases a single discharge conveyor may be provided, and the discharge conveyor may extend through a communicating opening in either of the end walls, and indeed, in cases where a single discharge conveyor is provided, it is envisaged that a construction of apparatus similar to that of Figs. 6 to 8 would be provided where only a single communicating opening would be provided and the slurry would be delivered through that single communicating opening, and the slurry residue and discharge conveyor would exit through the single communicating opening.
  • a pair of discharge chutes could be provided similar to the chute and hopper arrangement of the apparatus of Figs. 6 to 8, in which case it is envisaged that the hoppers may be carried on a carrier means for facilitating axial movement of the discharge chutes through the hollow interior region for varying the maximum and minimum grade sizes discharged through the respective discharge chutes.
  • each discharge means may be provided, and the discharge means would be arranged so that each discharge means collected sand of different grade sizes.
  • any other suitable discharge means besides discharge conveyors or discharge chutes may be provided.
  • rollers 5 and 6 have been described respectively as being drive and idler rollers, it is envisaged in certain cases that both the rollers 5 and 6 will act as drive rollers, and each would be driven by the main drive motor.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Filtration Of Liquid (AREA)
  • Treatment Of Sludge (AREA)

Abstract

Apparatus for separating and dewatering sand in suspension in a slurry with other solids of lower density to that of the sand comprises a drum (2) rotatably carried on rollers (5, 6) on a base framework (3). The slurry is delivered into the drum (2) through a delivery pipe (24), and sand settles downwardly from the slurry to a lower portion (32) of the drum (2), and is transferred by perforated transfer panels (35) as the drum (2) rotates into discharge conveyors (38, 39) for discharge through communicating openings (20, 21) in end walls (16, 17) of the drum (2). The slurry residue with the entrained lower density is discharged through the communicating opening (21) and collected in a collecting sump (29). The sand settles out of the slurry in progressively reducing grade size from the end wall (16) to the end wall (17). The discharge conveyors (38, 39) are slideably carried on carrier tracks (45) and are axially moveable in the drum (2) for varying the grade size of sand discharged by each discharge conveyor (38, 39).

Description

"Dewatering apparatus"
The present invention relates to apparatus for dewatering sand in a slurry suspension of sand and other solids which are of lower density size to that of the sand. Such solids typically are soil, clay, and other organic particulate material which is typically found in sand and gravel pits.
Sand when quarried typically comprises other solid matter, such as soil, clay and other organic matter. The sand must be separated from all such non-sand matter, and this typically is carried out by a washing process whereby the non-sand matter is washed from the sand. During the washing process water is added to the sand and non-sand matter to form a slurry. Using various separating techniques which generally are referred to as dewatering processes, the sand is initially separated from the non-sand matter, and then the water and sand are separated from each other. Such dewatering processes tend to be relatively complex and expensive to install. Additionally, many known dewatering apparatus tend to be inefficient, in that sand may be lost in the dewatering process, or alternatively soil and other fine particulate matter may be carried with the sand. This is undesirable.
Typically, such known apparatus comprises a settling tank into which the slurry of sand and other solids, namely, non-sand matter is continuously delivered. The sand settles out of the slurry to the base of the tank, and the slurry with the non-sand matter flows from the tank over a weir. A transfer mechanism, which may be provided by a plurality of transfer buckets which are located around the periphery of a rotatably mounted transfer framework, collects the sand which has settled to the base of the tank and transfers it upwardly for delivery into a chute. The buckets are perforated for facilitating dewatering of the sand as it is being transferred upwardly from the tank to the chute. A particular disadvantage of this type of apparatus is that the entire base of the tank is not swept by the transfer mechanism, and thus other mechanisms are required for urging the settled sand in the tank towards the transfer mechanism. Such mechanisms for urging the sand towards the transfer mechanism tend to cause turbulence in the slurry which inhibits settling of the sand, thereby leading to loss of significant volumes of sand which flow with the slurry from the tank.
There is therefore a need for dewatering apparatus which overcomes this problem.
The present invention is directed towards providing such a dewatering apparatus.
According to the invention there is provided apparatus for dewatering sand in a slurry suspension of sand and other solids, the other solids being of lower density to that of the sand, wherein the apparatus comprises a housing defining a geometric central axis and a hollow interior region extending axially between a pair of spaced apart axially opposite end walls, and being rotatably mounted about its central axis, a delivery means for delivering the slurry into the hollow interior region through one of the end walls, a discharge means for discharging dewatered sand from the hollow interior region through one of the end walls, a transfer means located in the hollow interior region for transferring sand to the discharge means as the housing is rotating and for dewatering the sand as the sand is being transferred to the discharge means, an outlet from the hollow interior region extending through one of the end walls through which slurry residue with the solids of lower density to that of the sand suspended therein is discharged from the hollow interior region, and a main drive means for rotating the housing about the central axis.
In one embodiment of the invention the outlet and the delivery means extend through the same end wall.
Alternatively, the end wall of the two end walls through which the outlet extends is different to the end wall through which the delivery means extends.
In another embodiment of the invention the discharge means and the delivery means extend through the same end wall. In a further embodiment of the invention the end wall of the two end walls through which the discharge means extends is different to the end wall through which the delivery means extends.
Preferably, the delivery means extends into the hollow interior region, and terminates in a delivery port which is located relative to the outlet for delivering the slurry into the hollow interior region so that the slurry flows axially from the delivery port to the outlet for facilitating precipitation of the sand out of suspension in the slurry in the hollow interior region for collection by the transfer means.
Advantageously, the delivery means and the outlet are located relative to each other so that as the slurry flows through the hollow interior region from the delivery means to the outlet with the sand precipitating out of suspension in the slurry in progressively reducing grade size from the delivery means to the outlet.
Ideally, the slurry is delivered into the hollow interior region by the delivery means so that the solids of lower density to that of the sand remain entrained in the slurry in the hollow interior region at a level above that at which the sand is collected by the transfer means.
In one embodiment of the invention the delivery means delivers the slurry into the hollow interior region such that the sand precipitates downwardly out of suspension in the slurry so that the precipitating sand is graded by size in an axial direction across the hollow interior region. Preferably, the sand of largest grade is located in the hollow interior region towards one end wall of the housing, and the grade reduces progressively in an axial direction towards the other end wall.
In one embodiment of the invention a pair of discharge means is provided, the respective discharge means extending through the respective end walls of the housing.
In another embodiment of the invention the respective discharge means are located within the hollow interior region so that sand of larger grade is transferred by the transfer means onto one of the discharge means, than onto the other of the discharge means.
In a further embodiment of the invention the respective positions of the respective discharge means are axially variable within the hollow interior region for varying the grade size of sand transferred onto the respective discharge means by the transfer means.
In one embodiment of the invention each discharge means comprises a chute extending from a hopper located in the hollow interior region.
Alternatively, each discharge means comprises a discharge conveyor extending from within the hollow interior region.
In one embodiment of the invention each discharge conveyor is provided by an endless conveyor belt.
In another embodiment of the invention a carrier means extends through the housing parallel to the central axis thereof for carrying each discharge means. Preferably, each discharge means is slideably carried on the carrier means for axially adjusting the position of each discharge means for varying the grade of sand transferred onto the respective discharge means from the transfer means.
Advantageously, a guide means is located within the hollow interior region for guiding the sand being transferred by the transfer means onto the corresponding discharge means.
In one embodiment of the invention a communicating opening is provided in each end wall through which any one of the delivery means, the discharge means or the outlet extends therethrough for accommodating the respective delivery means, discharge means or outlet. Preferably, each end wall communicating opening is coaxial with the central axis of the housing. Advantageously, the communicating opening in one of the end walls defines the outlet. Preferably, the communicating opening which defines the outlet defines a circumferential periphery which forms a weir over which slurry residue passes for retaining the slurry at a predetermined level within the hollow interior region. Advantageously, an outwardly diverging lip extends from and around the communicating opening which defines the outlet for directing the sludge residue into a collecting means.
In one embodiment of the invention the delivery means comprises a delivery pipe extending into the hollow interior region through the corresponding communicating opening.
In another embodiment of the invention the central axis of the housing is substantially horizontal.
Advantageously, the transfer means collects the sand at a lower portion of the hollow interior region and transfers the sand to an upper portion of the hollow interior region for transferring the sand onto the discharge means. Preferably, the sand is transferred from the transfer means to the discharge means under gravity.
In one embodiment of the invention the lower portion of the housing at which the sand is collected by the transfer means is below the central axis, and the upper portion of the housing from which the sand is transferred from the transfer means to the discharge means is above the central axis.
In one embodiment of the invention the transfer means is perforated for straining the sand and for draining the liquid slurry from the sand in the transfer means.
Preferably, the grade of the perforations in the transfer means is such as to retain the sand therein but to permit passage of at least most of the solids of lower density and smaller particle size to that of the sand therethrough.
In one embodiment of the invention a plurality of the transfer means is provided and each transfer means comprises a plurality of transfer panels which extend axially within the hollow interior region for collecting the sand as the housing rotates. Advantageously, each transfer panel extends between and engages the respective opposite end walls of the housing. Preferably, each transfer panel co-operates with the housing for retaining the sand thereon as the sand is being transferred to the discharge means. Advantageously, each transfer panel extends in a generally inwardly radial, circumferential direction in the direction of rotation of the housing. Preferably, each transfer panel terminates in an axially extending edge at a position spaced apart from the outlet so that solids entrained in the slurry are not engaged by the transfer means as the housing rotates. Preferably, each transfer panel is of a mesh material, and advantageously, the transfer panels are equi-spaced circumferentially around the central axis.
In an alternative embodiment of the invention the transfer means is formed by an inner surface of the housing, and a dislodging means co-operating with the inner surface of the housing is provided for dislodging the sand from the inner surface for transfer to the discharge means. Preferably, the dislodging means is located within the hollow interior region above the discharge means.
In one embodiment of the invention the housing comprises a cylindrical wall extending between the respective end walls, and each transfer means extends from the cylindrical wall in a generally radial, circumferential direction in the direction of rotation of the housing.
In another embodiment of the invention the housing is carried on a pair of spaced apart rollers extending parallel to the central axis, one of the rollers being driven by the main drive means. Advantageously, the other of the two rollers is an idler roller. Preferably, each roller is flanged at respective opposite ends for retaining the housing in position on the respective rollers.
In one embodiment of the invention the housing is rotated by the main drive means at a speed which permits the sand to precipitate from the slurry for collection by the transfer means, but which is sufficient for maintaining the solids of density lower than the sand entrained in suspension in the slurry. Preferably, the housing is rotated at 1 a speed in the range of « rpm to 2 rpm. Advantageously, the housing is rotated at a speed in the range of 1/2 rpm to 1 Yz rpm. Ideally, the housing is rotated at a speed of approximately 1 rpm.
The advantages of the invention are many. The apparatus for dewatering sand according to the invention is a particularly efficient dewatering apparatus. It has been found in general that little or no sand is lost with the slurry residue which flows through the outlet from the hollow interior region of the housing. This is largely because turbulence in the slurry within the hollow interior region is minimised, thereby permitting virtually all of the sand particles to settle out of the slurry. The rotational speed of the housing can be maintained at a speed which minimises turbulence. The fact that the slurry is delivered directly into the housing which also acts as the transfer means contributes significantly to the advantages of the invention, by virtue of the fact that there is no need for any additional devices for urging sand which has settled from the slurry into the transfer means. The sand settles directly into the transfer means in the case of the apparatus according to the present invention.
A further advantage of the invention is achieved when the apparatus is provided with a pair of discharge means, the axial positions of which can be varied for varying the particle size of the sand discharged by the respective discharge means.
The invention will be more clearly understood from the following description of some preferred embodiments thereof, which are given by way of example only, with reference to the accompanying drawings in which:
Fig. 1 is a front end elevational view of apparatus according to the invention for dewatering sand in a slurry suspension of sand and other solids,
Fig. 2 is a partly cut away, partly cross-sectional front end elevational view of the apparatus of Fig. 1 , Fig. 3 is a partly cut away, partly cross-sectional side elevational view of the apparatus of Fig. 1 ,
Fig. 4 is a partly cut away, partly cross-sectional top plan view of the apparatus of Fig. 1 ,
Fig. 5 is a rear end elevational view of a portion of the apparatus of Fig. 1 ,
Fig. 6 is a partly cut away, partly cross-sectional rear end elevational view of apparatus according to another embodiment of the invention also for dewatering sand in a slurry suspension of sand and other solids,
Fig. 7 is a partly cut away, partly cross-sectional side elevational view of the apparatus of Fig. 6,
Fig. 8 is a top plan view of the apparatus of Fig. 6,
Fig. 9 is a partly cut away, partly cross-sectional front end elevational view of a portion of apparatus according to a further embodiment of the invention also for dewatering sand in a slurry suspension of sand and other solids,
Fig. 10 is a partly cut away, partly cross-sectional side elevational view of the portion of the apparatus of Fig. 9,
Fig. 11 is a partly cut away, partly cross-sectional rear end elevational view of the portion of the apparatus of Fig. 9, and
Fig. 12 is a cross-sectional end elevational view of a detail of the apparatus of Fig. 9.
Referring to the drawings, and initially to Figs. 1 to 5, there is illustrated dewatering apparatus according to the invention indicated generally by the reference numeral 1 for separating sand out of a slurry suspension of sand and other solids and for dewatering the sand, the other solids being of lower density to that of the sand. The apparatus 1 comprises a housing, in this embodiment of the invention provided by a cylindrical drum 2 which is rotatably carried on a base framework 3 by a pair of spaced apart parallel rollers, namely, a drive roller 5 and an idler roller 6. Bearings 8 rotatably support the drive and idler rollers 5 and 6 on the base framework 3 parallel to each other and parallel to a central geometric axis 10 of the drum 2 about which the drum 2 is rotatable. A main drive means comprising a main drive motor 12 mounted on the base framework 3 drives the drive roller 5 for rotating the drum 2 about the central axis 10 in the direction of the arrow A during the separating and dewatering process, as will be described below.
The cylindrical drum 2 comprises a cylindrical circumferentially extending side wall 15 which extends between a pair of axially opposite spaced apart end walls 16 and 17 which together with the side wall 15 define a hollow interior region 18 into which the slurry is delivered. A pair of communicating openings 20 and 21 are provided in the end walls 16 and 17 for providing access and egress to and from the hollow interior region 18. The openings 20 and 21 are centrally located in the end walls 16 and 17 and are co-axial with the central axis 10, the diameter of the communicating opening 21 being greater than that of the communicating opening 20.
A delivery means provided by a delivery pipe 24 delivers the slurry of water, of sand and other solids into the hollow interior region 18. The delivery pipe 24 extends through the communicating opening 20 in the end wall 16 and terminates in a delivery port 25 through which the slurry is delivered into the hollow interior region 18. The communicating opening 21 in the end wall 17 forms an outlet 27 from the hollow interior region 18 through which a slurry residue of water and non-sand solids entrained in the slurry residue is delivered from the hollow interior region 18. The communicating opening 21 defines a circumferentially extending peripheral edge 28 which forms a weir over which the slurry residue flows from the hollow interior region 18 into a collecting means, namely, a collecting sump 29. An outwardly diverging lip 30 extends around and outwardly from the circumferential edge 28 of the communicating opening 21 for directing the slurry residue from the outlet 27 into the collecting sump 29. Since the diameter of the opening 21 is greater than that of the opening 20, the peripheral edge 28 which forms the weir as the drum 2 is rotating determines the level at which the slurry is retained in the hollow interior region 18, and thus retains the slurry in the hollow interior region 18 at a predetermined level.
The delivery port 25 is located in the hollow interior region 18 at a level which is just above the level at which the slurry is retained in the hollow interior region 18 by the outlet 27 and relatively close to the end wall 16, so that the slurry flows in an axial direction across the drum 2 from the delivery port 21 adjacent the end wall 16 to the outlet 27 in the end wall 17. Because the slurry flows in a direction from the end wall 16 to the end wall 17, the smaller grade sand particles are carried in suspension towards the outlet 27 and progressively precipitate downwardly out of suspension into a lower portion 32 of the drum 2, the smallest grade particles being carried the greatest distance towards the end wall 17. The largest grade particles because of their weight fall almost directly from the delivery port 25 downwardly to settle in the lower portion 32 of the drum 2. Accordingly, the sand precipitates downwardly out of suspension into the lower portion 32 of the drum 2 with the sand grade becoming progressively smaller from the largest grade to the smallest grade from the end wall 16 to the end wall 17, respectively. The drum 2 is rotated at a speed, which in this embodiment of the invention is approximately 1 rpm, which is just sufficient to maintain the solids of lower density to that of the sand in suspension above the lower level 32 at which the sand settles downwardly in the drum 2, while at the same time the rotational speed of the drum is sufficiently slow to permit the sand to precipitate downwardly out of suspension within the hollow interior region 18.
A plurality of transfer means comprising a plurality of transfer panels 35 extending between the end walls 16 and 17 and from the cylindrical side wall 15 collect the sand which is precipitating downwardly in the lower portion 32 as the drum 2 is rotating, and transfer the collected sand upwardly from the lower portion 32 to an upper portion 36. As the transfer panels 35 sequentially reach the upper portion 36 the sand falls under gravity onto a pair of discharge means, namely, a pair of discharge conveyors 38 and 39 which extend through the respective communicating openings 20 and 21 , respectively, for discharging dewatered sand from the hollow interior region 18. The transfer panels 35 are of perforated mesh material having an appropriate mesh size such as to retain sand of particles above a predetermined minimum particle size, while permitting the water and any other solids of lesser particulate size to pass therethrough. Typically, the mesh size would range between 1mm and 6mm. The transfer panels 35 are equi-spaced circumferentially around and extend from the cylindrical side wall 15 in a generally radial, circumferential direction and in a circumferential direction in the direction of rotation of the drum 2, and thus, co-operate with the cylindrical side wall 15 for retaining the sand collected in the lower portion 32 of the hollow interior region 18 until the transfer panels 35 reach the upper portion 36 of the hollow interior region 18. Each transfer panel 35 extends from the cylindrical side wall 15 and terminates in an axially extending edge 37 at a position spaced apart from outlet 27 so that as the drum 2 rotates the transfer panels 35 clear the solids entrained in the slurry flowing between the delivery port 25 and the outlet 27.
Each discharge conveyor 38 and 39 comprises an endless conveyor belt 40 which extends between and is carried on a corresponding pair of carrier rollers 41. The carrier rollers 41 extend between and are rotatably carried in a pair of spaced apart side support members 42. A secondary drive means, namely, a pair of secondary drive motors (not shown) mounted on one of the side support members 42 each drive a corresponding one of the carrier rollers 41 of each discharge conveyor 38 and 39 for driving the respective endless conveyor belts 40 in the directions of the arrows C and D for discharging the sand from the hollow interior region 18. A carrier means provided by a pair of spaced apart parallel carrier tracks 45 of channel construction extend through the hollow interior region 18 and through the communicating openings 20 and 21 for slideably carrying the respective discharge conveyors 38 and 39 axially through the hollow interior region 18. Upstanding supports 46 extending upwardly from the base framework 3 support the carrier tracks 45. Two bearing rollers 44 rotatably carried on and extending sidewardly from each side support member 42 rollably engage a lower web 47 of the adjacent carrier track 45 for facilitating axial sliding of the discharge conveyors 38 and 39 along the carrier tracks 45. A guide means provided by a pair of spaced apart inclined main guide plates 48 located within the hollow interior region 18 and supported on support stays 49 which extend upwardly from the carrier tracks 45 guide sand falling under gravity from the transfer panels 35 onto the respective discharge conveyors 38 and 39. A pair of secondary guide plates 50 which are carried on a support bracket 52 extending upwardly from the respective side support members 42 of the discharge conveyors 38 and 39 guide the sand falling under gravity from the transfer panels 35 onto the discharge conveyors 38 and 39 at the respective ends thereof within the hollow interior region 18.
By sliding the discharge conveyors 38 and 39 in the direction of the arrows E or F the maximum grade size of sand collected on the discharge conveyor 39 can be varied, while the minimum grade size of sand collected on the discharge conveyor 38 can also be varied. In other words, by sliding the respective discharge conveyors 38 and 39 in the direction of the arrow E, the maximum grade size of sand collected on the discharge conveyor 39 is increased, while the minimum grade size of sand collected on the discharge conveyor 18 is also increased. Sliding the discharge conveyors 38 and 39 in the direction of the arrows F decreases the minimum grade size of sand which is collected on the discharge conveyor 38, and also decreases the maximum grade size of sand which is collected on the discharge conveyor 39. This is by virtue of the fact that the grade size of sand which precipitates out of the slurry in the lower portion 32 of the hollow interior region 18 progressively decreases from the end wall 16 to the end wall 17.
A sump outlet 54 from the collecting sump 29 is provided for discharging the slurry residue which collects in the collecting sump 29 for further treatment.
The drive and idler rollers 5 and 6 each comprise a drive shaft 55 which is rotatably carried in the bearings 8, and respective roller portions 56 for rollably carrying the drum 2. End flanges 57 extending around the roller portions 56 locate and retain the drum 2 on the respective rollers 5 and 6 during rotation. In use, with the drum 2 rotating at approximately 1 rpm in the direction of the arrow A, and the discharge conveyors operating, a slurry of water with sand and other solid matter in suspension from which the sand is to be separated is delivered through the delivery pipe 24 into the hollow interior region 18. The sand commences to precipitate out and downwardly of the slurry into the lower portion 32 with the grade of sand progressively reducing from the end wall 16 to the end wall 17. Solids of lower density to that of the sand remain entrained in the slurry which is delivered as a slurry residue through the outlet 27 and collected in the sump 29. The sand precipitating out of the slurry in the lower portion 32 is collected by the transfer panels 35 and transferred onto the respective discharge conveyors 38 and 39 as the drum 2 rotates. As the transfer panels 35 pass out of the slurry any slurry of water and other solids of particle size less than the mesh size remaining on the transfer panels 35 drain through the perforations of the transfer panels 35, thereby leaving dewatered sand to be transferred onto the discharge conveyors 38 and 39. The respective positions of the discharge conveyors 38 and 39 are selected so that sand of the desired grades is collected on the respective discharge conveyors 38 and 39 and discharged out of the hollow interior region 18 in the direction of the arrows C and D.
Referring now to Figs. 6 to 8, there is illustrated apparatus according to another embodiment of the invention, which is indicated generally by the reference numeral 60, also for separating sand from a slurry of sand and other solids in suspension of lower density to that of the sand. The apparatus 60 is substantially similar to the apparatus 1 and similar components are identified by the same reference numerals. The main difference between the apparatus 60 and the apparatus 1 is that only the end wall 17 is provided with a communicating opening 21. No communicating opening is provided in the end wall 16. In this embodiment of the invention the communicating opening 21 also forms the outlet 27, but as well as that accommodates the delivery pipe 24 into the hollow interior region 18. Instead of the discharge means being provided by a discharge conveyor, in this embodiment of the invention the discharge means is provided by a discharge chute 62 which inclines downwardly through the communicating opening 21 and extends from a hopper 63 located within the hollow interior region 18 for collecting sand delivered under gravity from the transfer panels 35. In this embodiment of the invention the delivery pipe 24 extends inwardly into the hollow interior region 18 and terminates in the delivery port 25 adjacent the end wall 16 for providing axial flow of the slurry from the delivery port 25 to the outlet 27 for facilitating precipitation of the sand downwardly out of suspension as the slurry flow axially from the delivery port 25 to the outlet 27. However, since in this embodiment of the invention only one single chute 62 is provided from the hollow interior region 18, the sand is delivered from the hollow interior region 18 ungraded.
Otherwise, operation of the apparatus 60 is similar to that of the apparatus 1.
Referring now to Figs. 9 to 12, there is illustrated apparatus according to another embodiment of the invention indicated generally by the reference numeral 70 for dewatering sand in a slurry suspension of sand and other solids. The apparatus 70 is particularly suitable for dewatering particularly fine sand of the type typically referred to as microfine or superfine sand, which typically, would be of maximum particle size not exceeding Vz mm. The apparatus 70 is substantially similar to the apparatus 1 described with reference to Figs. 1 to 5, and similar components are identified by the same reference numerals. The main differences between the apparatus 70 and the apparatus 1 is that firstly, the apparatus 1 is provided with only one single discharge conveyor 38, and secondly, in this embodiment of the invention the transfer means instead of being provided by transfer panels 35 is provided by an inner surface 71 of the cylindrical side wall 15 of the drum 2. The discharge conveyor 38 is carried directly on the upstanding supports 56 and is not moveable axially within the hollow interior region 18 of the drum 2.
In this embodiment of the invention, because the apparatus 70 is specifically suitable for dewatering microfine and superfine sand, it has been found that the wet sand particles because of their size and weight adhere to the inner surface 71 of the cylindrical side wall 15 by surface tension. Thus, as the drum 2 rotates, the inner surface 71 picks up the sand particles in the lower portion 32 of the hollow interior region 18, and the particles are transferred upwardly out of the slurry into the upper portion 36 of the hollow interior region 18 of the drum 2 on the inner surface 71 of the cylindrical side wall 15, as the drum 2 rotates in the direction of the arrow A. A dislodging means for dislodging the sand particles from the inner surface 71 of the side wall 15 comprises a scraper 73 which is carried on a support member 74 extending upwardly from one of the side support members 42 of the discharge conveyor 38. The scraper 73 is of resilient flexible plastics material and is secured in a mounting bracket 75 mounted on the support member 74. The scraper 73 extends axially across the hollow interior region 18 between the respective end walls 16 and 17 for scraping the entire inner surface 71 of the side wall 15 across its axial width. In this embodiment of the invention the main guide plate 48 is carried on the support member 74.
Additionally, by virtue of the fact that the apparatus 70 is particularly suitable for dewatering microfine and superfine sand, the diameter of the outlet 27 is considerably greater than the outlets 27 of the apparatus 1 and 60. This is because in this embodiment of the invention the transfer plates are omitted, and thus there is no need to maintain the level of water in the hollow interior region at a level well above the axial edges 37 of the transfer plates when extending upwardly from the bottom of the drum, and furthermore, it has been found desirable to maintain the level of the water in the drum relatively shallow when dewatering sand of microfine and superfine particle size.
Otherwise, the apparatus 70 is substantially similar to the apparatus 1 , and its operation is likewise similar, the only significant difference being that as the drum 2 rotates in the direction of the arrow A, the sand particles adhere by surface tension to the inner surface 71 and are transferred by the inner surface 71 as the drum 2 rotates from the lower portion 32 to the upper portion 36 of the drum, at which stage they are scraped from the inner surface 71 by the scraper 73. The main guide plate 48 collects the sand particles falling from the inner surface 71 , and directs the sand particles onto the discharge conveyor 38. Depending on the direction in which the discharge conveyor 38 is driven, the sand particles are discharged by the discharge conveyor, either through the opening 20 in the end wall 16 or through the opening 21 in the end wall 17 While in the apparatus described with reference to Figs. 1 to 5 the discharge means has been provided by a pair of discharge conveyors, it will be appreciated that in certain cases a single discharge conveyor may be provided, and the discharge conveyor may extend through a communicating opening in either of the end walls, and indeed, in cases where a single discharge conveyor is provided, it is envisaged that a construction of apparatus similar to that of Figs. 6 to 8 would be provided where only a single communicating opening would be provided and the slurry would be delivered through that single communicating opening, and the slurry residue and discharge conveyor would exit through the single communicating opening.
It is also envisaged that instead of providing the discharge means as a pair of discharge conveyors, a pair of discharge chutes could be provided similar to the chute and hopper arrangement of the apparatus of Figs. 6 to 8, in which case it is envisaged that the hoppers may be carried on a carrier means for facilitating axial movement of the discharge chutes through the hollow interior region for varying the maximum and minimum grade sizes discharged through the respective discharge chutes.
Indeed, it is envisaged in certain cases that more than two discharge means may be provided, and the discharge means would be arranged so that each discharge means collected sand of different grade sizes. Needless to say, any other suitable discharge means besides discharge conveyors or discharge chutes may be provided.
While the rollers 5 and 6 have been described respectively as being drive and idler rollers, it is envisaged in certain cases that both the rollers 5 and 6 will act as drive rollers, and each would be driven by the main drive motor.

Claims

Claims
1. Apparatus for dewatering sand in a slurry suspension of sand and other solids, the other solids being of lower density to that of the sand, characterised in that the apparatus (1) comprises a housing (2) defining a geometric central axis (10) and a hollow interior region (18) extending axially between a pair of spaced apart axially opposite end walls (16, 17), and being rotatably mounted about its central axis (10), a delivery means (24, 25) for delivering the slurry into the hollow interior region (18) through one of the end walls (16, 17), a discharge means (38, 39, 62, 63) for discharging dewatered sand from the hollow interior region (18) through one of the end walls (17, 18), a transfer means (35, 71 ) located in the hollow interior region (18) for transferring sand to the discharge means (38, 39, 62, 63) as the housing (2) is rotating and for dewatering the sand as the sand is being transferred to the discharge means (38, 39, 62, 63), an outlet (27) from the hollow interior region (18) extending through one of the end walls (17) through which slurry residue with the solids of lower density to that of the sand suspended therein is discharged from the hollow interior region (18), and a main drive means (12) for rotating the housing (2) about the central axis (10).
2. Apparatus as claimed in Claim 1 characterised in that the outlet (27) and the delivery means (24, 25) extend through the same end wall (17).
3. Apparatus as claimed in Claim 1 characterised in that the end wall (17) of the two end walls (16, 17) through which the outlet (27) extends is different to the end wall (16) through which the delivery means (24, 25) extends.
4. Apparatus as claimed in any preceding claim characterised in that the discharge means (38, 39, 62, 62) and the delivery means (24, 25) extend through the same end wall (17).
5. Apparatus as claimed in any preceding claim characterised in that the end wall (16, 17) of the two end walls (16, 17) through which the discharge means (38, 39, 62, 63) extends is different to the end wall (16, 17) through which the delivery means (24, 25) extends.
6. Apparatus as claimed in any preceding claim characterised in that the delivery means (24, 25) extends into the hollow interior region (18), and terminates in a delivery port (25) which is located relative to the outlet (27) for delivering the slurry into the hollow interior region (18) so that the slurry flows axially from the delivery port (25) to the outlet (27) for facilitating precipitation of the sand out of suspension in the slurry in the hollow interior region (18) for collection by the transfer means (35).
7. Apparatus as claimed in any preceding claim characterised in that the delivery means (24, 25) and the outlet (27) are located relative to each other so that as the slurry flows through the hollow interior region (18) from the delivery means (24, 25) to the outlet (27) with the sand precipitating out of suspension in the slurry in progressively reducing grade size from the delivery means (24, 25) to the outlet (27).
8. Apparatus as claimed in any preceding claim characterised in that the slurry is delivered into the hollow interior region (18) by the delivery means (24, 25) so that the solids of lower density and smaller size to that of the sand remain entrained in the slurry in the hollow interior region (18) at a level above that at which the sand is collected by the transfer means (35, 71 ).
9. Apparatus as claimed in any preceding claim characterised in that the delivery means (24, 25) delivers the slurry into the hollow interior region (18) such that the sand precipitates downwardly out of suspension in the slurry so that the precipitating sand is graded by size in an axial direction across the hollow interior region (18).
10. Apparatus as claimed in Claim 9 characterised in that the sand of largest grade is located in the hollow interior region (18) towards one end wall (16) of the housing (2), and the grade reduces progressively in an axial direction towards the other end wall (17).
11. Apparatus as claimed in any preceding claim characterised in that a pair of discharge means (38, 39) is provided, the respective discharge means (38, 39) extending through the respective end walls (16, 17) of the housing (2).
12. Apparatus as claimed in Claim 11 characterised in that the respective discharge means (38, 39) are located within the hollow interior region (18) so that sand of larger grade is transferred by the transfer means (35, 71 ) onto one of the discharge means (38, 39), than onto the other of the discharge means (38, 39).
13. Apparatus as claimed in Claim 11 or 12 characterised in that the respective positions of the respective discharge means (38, 39) are axially variable within the hollow interior region (18) for varying the grade size of sand transferred onto the respective discharge means (38, 39) by the transfer means (35, 71 ).
14. Apparatus as claimed in any preceding claim characterised in that each discharge means (38, 39, 62, 63) comprises a chute (62) extending from a hopper (63) located in the hollow interior region (18).
15. Apparatus as claimed in any of Claimsl to 13 characterised in that each discharge means (38, 39) comprises a discharge conveyor extending from within the hollow interior region (18).
16. Apparatus as claimed in Claim 15 characterised in that each discharge conveyor (38, 39) is provided by an endless conveyor belt (40).
17. Apparatus as claimed in any preceding claim characterised in that a carrier means (45) extends through the housing (2) parallel to the central axis (10) thereof for carrying each discharge means (38, 39).
18. Apparatus as claimed in Claim 17 characterised in that each discharge means (38, 39) is slideably carried on the carrier means (45) for axially adjusting the position of each discharge means (38, 39) for varying the grade of sand transferred onto the respective discharge means (38, 39) from the transfer means (35, 71).
19. Apparatus as claimed in any preceding claim characterised in that a guide means (48, 50) is located within the hollow interior region (18) for guiding the sand being transferred by the transfer means (35, 71) onto the corresponding discharge means (38, 39).
20. Apparatus as claimed in any preceding claim characterised in that a communicating opening (20, 21) is provided in each end wall (16, 17) through which any one of the delivery means (24, 25), the discharge means (38, 39, 62, 63) or the outlet (27) extends therethrough for accommodating the respective delivery means, discharge means or outlet.
21. Apparatus as claimed in Claim 20 characterised in that each end wall communicating opening (20, 21) is co-axial with the central axis (10) of the housing
(2).
22. Apparatus as claimed in Claim 20 or 21 characterised in that the communicating opening (21) in one of the end walls (17) defines the outlet (27).
23. Apparatus as claimed in Claim 22 characterised in that the communicating opening (21) which defines the outlet (27) defines a circumferential periphery which forms a weir over which slurry residue passes for retaining the slurry at a predetermined level within the hollow interior region (18).
24. Apparatus as claimed in Claim 23 characterised in that an outwardly diverging lip (30) extends from and around the communicating opening (21 ) which defines the outlet (27) for directing the sludge residue into a collecting means (29).
25. Apparatus as claimed in any of Claims 20 to 24 characterised in that the delivery means (24, 25) comprises a delivery pipe (24) extending into the hollow interior region (18) through the corresponding communicating opening (16, 17).
26. Apparatus as claimed in any preceding claim characterised in that the central axis (10) of the housing (2) is substantially horizontal.
27. Apparatus as claimed in any preceding claim characterised in that the transfer means (35, 71 ) collects the sand at a lower portion (32) of the hollow interior region (18) and transfers the sand to an upper portion (36) of the hollow interior region (18) for transferring the sand onto the discharge means (38, 39, 62, 63).
28. Apparatus as claimed in Claim 27 characterised in that the sand is transferred from the transfer means (35, 71 ) to the discharge means (38, 39, 62, 63) under gravity.
29. Apparatus as claimed in Claim 27 or 28 characterised in that the lower portion (32) of the housing (2) at which the sand is collected by the transfer means (35) is below the central axis (10), and the upper portion (36) of the housing (2) from which the sand is transferred from the transfer means (35, 71 ) to the discharge means (38, 39, 62, 63) is above the central axis (10).
30. Apparatus as claimed in any preceding claim characterised in that the transfer means (35) is perforated for straining the sand and for draining the liquid slurry from the sand in the transfer means (35).
31. Apparatus as claimed in Claim 30 characterised in that the grade of the perforations in the transfer means (35) is such as to retain the sand therein but to permit passage of at least most of the solids of lower density and smaller particle size to that of the sand therethrough.
32. Apparatus as claimed in any preceding claim characterised in that a plurality of the transfer means (35) is provided and each transfer means (35) comprises a plurality of transfer panels (35) which extend axially within the hollow interior region (18) for collecting the sand as the housing (2) rotates.
33. Apparatus as claimed in Claim 32 characterised in that each transfer panel (35) extends between and engages the respective opposite end walls (16, 17) of the housing (2).
34. Apparatus as claimed in Claim 32 or 33 characterised in that each transfer panel (35) co-operates with the housing (2) for retaining the sand thereon as the sand is being transferred to the discharge means (38, 39, 62, 63).
35. Apparatus as claimed in any of Claims 32 to 34 characterised in that each transfer panel (35) extends in a generally inwardly radial, circumferential direction in the direction of rotation of the housing (2).
36. Apparatus as claimed in any of Claims 32 to 35 characterised in that each transfer panel (35) terminates in an axially extending edge (37) at a position spaced apart from the outlet (27) so that solids entrained in the slurry are not engaged by the transfer means (35, 71 ) as the housing (2) rotates.
37. Apparatus as claimed in any of Claims 32 to 36 characterised in that each transfer panel (35) is of a mesh material.
38. Apparatus as claimed in any of Claims 32 to 37 characterised in that the transfer panels (35) are equi-spaced circumferentially around the central axis (10).
39. Apparatus as claimed in any of Claims 1 to 29 characterised in that the transfer means (35, 71 ) is formed by an inner surface (71 ) of the housing (2), and a means (73) co-operating with the inner surface (71 ) of the housing (2) is provided for dislodging the sand from the inner surface (71) for transfer to the discharge means (38, 39, 62, 63).
40. Apparatus as claimed in Claim 39 characterised in that the dislodging means (73) is located within the hollow interior region (18) above the discharge means (38,
39, 62, 63).
41. Apparatus as claimed in any preceding claim characterised in that the housing (2) comprises a cylindrical wall (15) extending between the respective end walls (16, 17), and each transfer means (35) extends from the cylindrical wall (15) in a generally radial, circumferential direction in the direction of rotation of the housing (2).
42. Apparatus as claimed in any preceding claim characterised in that the housing (2) is carried on a pair of spaced apart rollers (5, 6) extending parallel to the central axis ( 0), one of the rollers (5) being driven by the main drive means (12).
43. Apparatus as claimed in Claim 42 characterised in that the other of the two rollers is an idler roller (6).
44. Apparatus as claimed in Claim 42 or 43 characterised in that each roller (5, 6) is flanged (57) at respective opposite ends for retaining the housing (2) in position on the respective rollers (5, 6).
45. Apparatus as claimed in any preceding claim characterised in that the housing (2) is rotated by the main drive means (12) at a speed which permits the sand to precipitate from the slurry for collection by the transfer means (35), but which is sufficient for maintaining the solids of density lower than the sand entrained in suspension in the slurry.
46. Apparatus as claimed in any preceding claim characterised in that the
1 housing (2) is rotated at a speed in the range of Q rpm to 2 rpm.
47. Apparatus as claimed in Claim 46 characterised in that the housing (2) is rotated at a speed in the range of 1/2 rpm to VA rpm.
48. Apparatus as claimed in Claim 47 characterised in that the housing (2) is rotated at a speed of approximately 1 rpm.
PCT/IE2001/000043 2000-03-29 2001-03-29 Dewatering apparatus WO2001072426A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001242710A AU2001242710A1 (en) 2000-03-29 2001-03-29 Dewatering apparatus

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IE20000235 2000-03-29
IES2000/0235 2000-03-29

Publications (1)

Publication Number Publication Date
WO2001072426A1 true WO2001072426A1 (en) 2001-10-04

Family

ID=11042587

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IE2001/000043 WO2001072426A1 (en) 2000-03-29 2001-03-29 Dewatering apparatus

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AU (1) AU2001242710A1 (en)
IE (1) IES20010311A2 (en)
WO (1) WO2001072426A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102019218403A1 (en) * 2019-11-27 2021-05-27 ISV Umwelt UG Device for thickening a mixture and method of operating the device

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US2765915A (en) * 1953-11-16 1956-10-09 Nilsson Ivar Linus Method of and means for recovering fibers from pulp-water
US4043901A (en) * 1975-12-03 1977-08-23 Gauld Equipment Sales Company Wood chip screens
AU1897576A (en) * 1976-10-25 1978-05-04 Masuda M Sand washer
US4204855A (en) * 1978-04-18 1980-05-27 SIDMAR Maritieme Staalnihverheid N.V. Siderurgie Maritime S.A. Apparatus for dewatering granulated-slag slurry
US4477349A (en) * 1983-02-10 1984-10-16 Guido Monteyne Metalurigical slag filtering apparatus
US4493767A (en) * 1983-04-28 1985-01-15 Guido Monteyne Conveyor belt for transporting slag material from a filtering apparatus
US4518498A (en) * 1983-02-10 1985-05-21 Paul Wurth S.A. Metallurgical slag filtering apparatus which effects uniform charging of a conveyer belt
US5853585A (en) * 1994-12-14 1998-12-29 Nth, Inc. Rotary separator apparatus

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2765915A (en) * 1953-11-16 1956-10-09 Nilsson Ivar Linus Method of and means for recovering fibers from pulp-water
US4043901A (en) * 1975-12-03 1977-08-23 Gauld Equipment Sales Company Wood chip screens
AU1897576A (en) * 1976-10-25 1978-05-04 Masuda M Sand washer
US4204855A (en) * 1978-04-18 1980-05-27 SIDMAR Maritieme Staalnihverheid N.V. Siderurgie Maritime S.A. Apparatus for dewatering granulated-slag slurry
US4477349A (en) * 1983-02-10 1984-10-16 Guido Monteyne Metalurigical slag filtering apparatus
US4518498A (en) * 1983-02-10 1985-05-21 Paul Wurth S.A. Metallurgical slag filtering apparatus which effects uniform charging of a conveyer belt
US4493767A (en) * 1983-04-28 1985-01-15 Guido Monteyne Conveyor belt for transporting slag material from a filtering apparatus
US5853585A (en) * 1994-12-14 1998-12-29 Nth, Inc. Rotary separator apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102019218403A1 (en) * 2019-11-27 2021-05-27 ISV Umwelt UG Device for thickening a mixture and method of operating the device

Also Published As

Publication number Publication date
AU2001242710A1 (en) 2001-10-08
IES20010311A2 (en) 2001-10-03

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