CA1243985A - Particle size range separations prior to de-watering - Google Patents
Particle size range separations prior to de-wateringInfo
- Publication number
- CA1243985A CA1243985A CA000423841A CA423841A CA1243985A CA 1243985 A CA1243985 A CA 1243985A CA 000423841 A CA000423841 A CA 000423841A CA 423841 A CA423841 A CA 423841A CA 1243985 A CA1243985 A CA 1243985A
- Authority
- CA
- Canada
- Prior art keywords
- particles
- fraction
- suspension
- dewatering
- slag
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D36/00—Filter circuits or combinations of filters with other separating devices
-
- 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
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
-
- 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
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/04—General arrangement of separating plant, e.g. flow sheets specially adapted for furnace residues, smeltings, or foundry slags
-
- 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
- B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
- B03D3/00—Differential sedimentation
- B03D3/06—Flocculation
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
- Treatment Of Sludge (AREA)
- Centrifugal Separators (AREA)
Abstract
A B S T R A C T
PARTICLE SIZE RANGE SEPARATIONS
PRIOR TO DE-WATERING
An aqueous suspension of slag particles is dewatered by dividing the suspension in three fractions containing coarse, intermediate and fine particles respectively, and by dewatering the fractions separately.
An aqueous suspension of slag particles obtained as a by-product in a coal gasification process is very difficult to dewater as such. By dividing such a suspension in three separate fractions and applying the most appropriate dewatering method for each fraction, this difficulty is obviated.
PARTICLE SIZE RANGE SEPARATIONS
PRIOR TO DE-WATERING
An aqueous suspension of slag particles is dewatered by dividing the suspension in three fractions containing coarse, intermediate and fine particles respectively, and by dewatering the fractions separately.
An aqueous suspension of slag particles obtained as a by-product in a coal gasification process is very difficult to dewater as such. By dividing such a suspension in three separate fractions and applying the most appropriate dewatering method for each fraction, this difficulty is obviated.
Description
~Z~39135 329:~-2279 PARTICLE SIZE RANGE SEPAR~TIONS
PRIOR TO DE-WATERING
The invention relates to a method for the dewatering of an aqueous suspension of slag particles.
When an ash-containing fuel is fully combusted, slag is obtained as a by-product. The combustion takes place in a reactor and the resultant slag is generally trapped in a water bath located underneath the reactor. In slurry form the slag is comparatively simple to convey.
; 10 Slag is also formed in the partial com~ustion of an ash-containing fuel such as coal, lignite, peat etc. Here, too, the resultant slag is usually trapped in a water bath, yielding an aqueous suspension. The aqueous suspension is than discharged from the water bath. Because it is preferred to maintain an elevated pressure in the reactor, a sluice system is used in order to dis-charge the aqueoussuspension. A~suitable method for this purpose is described in the US patent specification No. 3,994,702.
It is generally not possible to process or dispose of the aqueous suspension as such, so that is is very desirable to ~ : : 20 dewater the suspension. The slag particles can be subsequently reprocessed and empolyed for other~purposes, for example in road construction. The clhri~ied water can be discharged without entailing any danger to the environment.
If dewatering o-f the supension is carried ou~ b~ means of screen units, small slag particles in the suspension are not caught by the screen units but~ilow along with the water phase.
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-la- 63293-2279 On the other hand, if a filter is used, the small slag particles may cause blockages in the filter. It is possible to cause the fine particles to agglomerate into larger particles by means of a flocculant. In that case, however, the larger particles also react with the flocculant. In order to cause all the small particles to agglomerate, it is therefore necessary to add a comparatively large quantity of flocculant to the suspension.
That is uneconomic.
3~5 For that reason, iXL the method according to thLe invention the slag particles are separated according to diameter si2e. The present invention therefore relates to a method for the dewatering of an aqueous suspension of slag particles, characterized in tha the suspension is separated into different fractions, containiny coarse, intermediate and fine particles, re~pecti~ely, and that the fractions are dewatered separately.
By using the methLod accordin~ to the invention it is possible to choose the most effective dewatering technique for each frac-tion. For pc~rticle size has an important influence on this choice.In the method according to the invention the separation between the coaLrse and inLtermediate particles is preferably effected at a diameter size from 0.5 to 2 mm, and e~en more preferably at 1 mm The separation between the intermediate and fine particles is preferably effected at a diameter size from O.Ol to O.l mm, and even m~re preferably at 5.06 mm. As a result of this the fraction with coarse particles preferably oontains substantially pa~ticles with a diameter larger than l mm, the fraction with intermediate particles preferably contains substantially particles with a i diclmeter in the range from 0.06 to l mm and ~he fraction with fine particles preferakly contains substantially particles with a diameter smaller than 0.06 mm.
e sequence in which tJ~suspension is separated into ~; fractions, hc~ever, is not of material i~portance. It is possible first to separate ~he fine particles from the coarse and interme-diate particles and subsequently to separate the remaining suspen-sion into one fraction~with coarse particles and another fraction with inte~mediate particles. For preference, however, the coarse particles are separated fram tJhe suspension first.
In order to sepaxate the coarse particles from the suspen-sion, use may be made of many types of separators. In de~ermuning the type of separator, the eroding or abrasive action of the slag particles is a factor to be considered.
~ydrocyclones, f~x exa~le, are exposed to the risk o serious damage. For that reason the fraction with coarse particles ' i .J
~ 39~35 is preferably separated from the suspension and also dewatered by means of one or more screen units. A preferred ~mbodime~t of the method according to the invention employs a static screen in order to separate the greater part of the water from the suspension whlle separating the coarse particles, followed by a vibrating screen in order to separate the remaining water, so that the fraction with coarse particles is sufficiently dewatered. 'L~ese separated coarse particles are discharged together for further processing.
0 m e remaining suspension containing the intermediate and fine particles is subsequently separated into two fractions. To that end it is conveyed to one or more classifying units. Various classifying units are suitable. A classifying screw or a classi-fying rake can be used. It is also possible to employ a hydroclassi-fying unit or an ordinary classifying cone. Preferably, however, the separation between the intermediate and fine particles is effected by means of one or more hydrocyclones. The eroding or abrasive action of the intermediate and fine particles is consider-ably smaller than that of the coarse particles. The risk of damage ~` 20 to the hydrocyclones is therefore small. ~oreover, the risk of damage is reduced even further by providing the interior of the -~ hydrocyclones with a suitable protective l ming. The hydrocyclones are so econcmic because they separate very selectively. That is to say that relatively few fine particles enter the fraction with 25 intermediate slag particles. ~
; The fraction with inter~ediate particles is then dewatered.
For this purpose various types of separators are suitable. Suit-able types are dewatering screen units (the "Fordertechnik screen"
and the "Elliptexrdewaterizer", see L. Sv~rcvsky, Solid-liquid 0 separation, Butterworths, 1979, pp. 165-167). A number of diffe-rent filtration units and dewatering screws are also suitable.
~ Preferably, the fraction with the coarse particles is de-; ~latered by means of one or more dewatering rakes. These units are ~ the cheapest and most reliable. Moreover, during the dewatering ;~ 35 treatment a further separation is ef~ected between the entrained * Trade Mark . ~
,.
~L2~3~5 fine particles and intermediate particles. m e aqueous phase, which therefore still conta ms a ~ew, substantially f me, slag particles, is preferably recycled to the classify mg units, in particular the hydrocyclones. This ensures that no polluted water enters the environment.
The fraction with fine particles w~ich is discharged frc~ the classifying units is preferably passed to one or more settling basins. There concentration of the fine slag particles takes place. Preferably the concentrate is passed to one or m~re filter presses where further dewatering takes place.
m e sedi~entation rate of the fine particles in the settling basins is lcw, because the dImensions of the particles are so small. Particles of colloidal dimensions will even not settle at all. It is therefore preferred to add a flocculant to the frac~ion with fine particles. The addition of flocculant may be made in the settling basins but also upstream thereof. Because a considerable proportion of slag particles has already been separated from the suspension, a ccmparatively small quantity of flocc~lant is ; sufficient. Suitable flocculants are various cationic and/or anionic polymers.
The wat~r leaving the settling basins, name~y the averflow, is clear and contains fewer than 50 pFm slag particles in the water. This overflow can be discharged l:nto the surface water without any risk of environmEnt pollution. It can also, at least ;~25 partly, be recycled to the process and used as wash mg water and/or transport medium. The filtrate from the filter presses still contains a minor quantity of slag particles. Because it is desired to separate this minor quantity frcm the suspension as well~ the filtrate is preferably recycled to the settling basms.
The m~ention will now be further elucidated with reference to the Figure, to ~7hich the invention is hawever by no means lim~ted. Cc~ressors, valves,~control equip~nt etc. are not shawn :: in the dia~natic figure.
Via a line 1 an aquecus suspensiQn of slag particles is 35 p ssed to a static screen 2. There a fraction with coarse~pa~
:
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cles is separated and dewatered. The coarse particles are passed via a gutter 3 to a vibrating screen 5, where further dewatering takes place. The dewatered coarse slag particles are discharged from ~le syste~ by means of a gutter 7 and a con~eyor kelt 8. The separated water containing the intermediate and ~lne p2rticles is passed through a line 4 from the static screen 2 and through a line 6 from the vibrating screen 5 to a line 9~ From there it is passed via a line 10 to a hydrocyclone 11, where the separation between the intexmediate and fine particles takes place. A sus-p~nsion containing substantially intermediate particles leaves thecyclone through a line 12, which carries the suspension to a dewatering rake 14. In this dewatering unit the intermediate ;~ particles are separated from the suspension and removed from the system via a gutter 15 and a conveyor belt 16. T.he aqueous sus-pension with fine particles is passed via a line 17 into the line 9, so that the suspensi~n is recycled via the line lO into the hydrocyclone ll.
An aqueous suspension with fine slag particles lea~es the ; hydrocyclone 11 through a line 13. In the line 13 an aqueous : 20 solution of flocculant îs added to the suspension fru~ a vessel 25 .~: via a line 26. The aqueous suspension with the flocculant is passed via a line 18 into a settling basin l9. m ere thi ~ of the:suspension takes place. The ~hickened suspension is passed through the bottom of the settl mg basin 19 via a line 20 to a ~ 25 filter press 22. m e slag particles dewatered there are disch3rged : frcm the sysbem via a line 23. The filtrate from the filter press 22 is recycled via a line 24~to:the suspension m the line 13.
~: ~ The over low from the settling basin 19 is discharged via a line 21. A portion of the clarified water is passed via a line 27 : 30 t~ the vibrat mg screen 5 where it is used as washing water. The remainLng portion of the clarified water is discharged from the system via a l me 28.
lthcugh:they are not shown ln the Figure, it is possible to : incorpDrate a number of buf~er:vessels in the ~ethod according to the invention m order to co~nteract:fluctuations in the fe~d to 398~i continuously oFerating installations, or in order to serve as storage vessels for units operating batchwise. Suit-~ble locations for a buffer vessel are upstream of the hydrocyclone, between the h~drocyclone and the settling basin, and between the settling 5 basin and the filter press.
EX~LE
In a plant as diagrammatically shown in the Figure the following experiment was carried out.
Via the line 1, 34.886 kg/s of water with 1.438 kg/s of slag ; 1~ particles is supplied. After separation on the static screen 2, the c se slag particles are washed on the vibrating screen with 5.94 kg/s of water from the line 27. ~his produces a stream of coarse slag particles of 0.708 kg/s with 0.236 kg/s of water which is discharged via the gutter 7 and conveyor belt 8 for further 15 treatment.
The suspensions frcm the lines 4 and 6 are ccmbined in the line 9, through which 40.59 kg of water and 0.73 kg of slag particles flow per second. Via the line 17, 3.76 kg/s of wat~r with O.I88 kg/s of slag particles is added t~ the stream in the 20 line 9. After separation in the hydrocyclone 11, via~the;line 12 a quantity of 3.87 kg/s of water and 0.430 kg/s of slag is passed to the dewatering rake 14, where 0.242 kg/s of coarse sl~g particles with 0.110 kg/s of water is separated.
Via the stream in the line 13 of 40.48 kg/s of water and 25 0.488 kg/s of fine slag particles, to which via the line 24 an ; amount of 4.06 kg/s of water and 0.027 kg/s of slag is added, in addition to O.Ol kg/s ~f water and 0.0002 kg/s of flocculant via the l m e 26, via the line 18 a quantity of 44.55 kg/s of water and 0.515 kg/s of slag and 0.0002 kg/s of flocculant is supplied to 30 the settling basin 19. Via the line 20 a quantity~of 4.39 kg/s with 0.515~kg/s of sl g and 0.0002 kg/ of flocculant is supplied ~ to the filter press 22. ~ ~
-~ ~ There 0.4882 kg/s of solid matter with 0.330 kg/s of water is ~ separated. The filtrate is~recycled via the line 24.
, ~ ~
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:
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-~2~398~i ~ 7 --From the settliny basin 19 a quantity of 40.16 kg/s of clearwater is discharged via the line 21. Of that quantity, 5.94 kg/s is passed to the vibrating screen 5 via the line 27, so that a quantit~ of 34.22 kg/s of water is discharged frcm the system via 5 the line 28.
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PRIOR TO DE-WATERING
The invention relates to a method for the dewatering of an aqueous suspension of slag particles.
When an ash-containing fuel is fully combusted, slag is obtained as a by-product. The combustion takes place in a reactor and the resultant slag is generally trapped in a water bath located underneath the reactor. In slurry form the slag is comparatively simple to convey.
; 10 Slag is also formed in the partial com~ustion of an ash-containing fuel such as coal, lignite, peat etc. Here, too, the resultant slag is usually trapped in a water bath, yielding an aqueous suspension. The aqueous suspension is than discharged from the water bath. Because it is preferred to maintain an elevated pressure in the reactor, a sluice system is used in order to dis-charge the aqueoussuspension. A~suitable method for this purpose is described in the US patent specification No. 3,994,702.
It is generally not possible to process or dispose of the aqueous suspension as such, so that is is very desirable to ~ : : 20 dewater the suspension. The slag particles can be subsequently reprocessed and empolyed for other~purposes, for example in road construction. The clhri~ied water can be discharged without entailing any danger to the environment.
If dewatering o-f the supension is carried ou~ b~ means of screen units, small slag particles in the suspension are not caught by the screen units but~ilow along with the water phase.
. ~
' `~ !
~ ~3~
-la- 63293-2279 On the other hand, if a filter is used, the small slag particles may cause blockages in the filter. It is possible to cause the fine particles to agglomerate into larger particles by means of a flocculant. In that case, however, the larger particles also react with the flocculant. In order to cause all the small particles to agglomerate, it is therefore necessary to add a comparatively large quantity of flocculant to the suspension.
That is uneconomic.
3~5 For that reason, iXL the method according to thLe invention the slag particles are separated according to diameter si2e. The present invention therefore relates to a method for the dewatering of an aqueous suspension of slag particles, characterized in tha the suspension is separated into different fractions, containiny coarse, intermediate and fine particles, re~pecti~ely, and that the fractions are dewatered separately.
By using the methLod accordin~ to the invention it is possible to choose the most effective dewatering technique for each frac-tion. For pc~rticle size has an important influence on this choice.In the method according to the invention the separation between the coaLrse and inLtermediate particles is preferably effected at a diameter size from 0.5 to 2 mm, and e~en more preferably at 1 mm The separation between the intermediate and fine particles is preferably effected at a diameter size from O.Ol to O.l mm, and even m~re preferably at 5.06 mm. As a result of this the fraction with coarse particles preferably oontains substantially pa~ticles with a diameter larger than l mm, the fraction with intermediate particles preferably contains substantially particles with a i diclmeter in the range from 0.06 to l mm and ~he fraction with fine particles preferakly contains substantially particles with a diameter smaller than 0.06 mm.
e sequence in which tJ~suspension is separated into ~; fractions, hc~ever, is not of material i~portance. It is possible first to separate ~he fine particles from the coarse and interme-diate particles and subsequently to separate the remaining suspen-sion into one fraction~with coarse particles and another fraction with inte~mediate particles. For preference, however, the coarse particles are separated fram tJhe suspension first.
In order to sepaxate the coarse particles from the suspen-sion, use may be made of many types of separators. In de~ermuning the type of separator, the eroding or abrasive action of the slag particles is a factor to be considered.
~ydrocyclones, f~x exa~le, are exposed to the risk o serious damage. For that reason the fraction with coarse particles ' i .J
~ 39~35 is preferably separated from the suspension and also dewatered by means of one or more screen units. A preferred ~mbodime~t of the method according to the invention employs a static screen in order to separate the greater part of the water from the suspension whlle separating the coarse particles, followed by a vibrating screen in order to separate the remaining water, so that the fraction with coarse particles is sufficiently dewatered. 'L~ese separated coarse particles are discharged together for further processing.
0 m e remaining suspension containing the intermediate and fine particles is subsequently separated into two fractions. To that end it is conveyed to one or more classifying units. Various classifying units are suitable. A classifying screw or a classi-fying rake can be used. It is also possible to employ a hydroclassi-fying unit or an ordinary classifying cone. Preferably, however, the separation between the intermediate and fine particles is effected by means of one or more hydrocyclones. The eroding or abrasive action of the intermediate and fine particles is consider-ably smaller than that of the coarse particles. The risk of damage ~` 20 to the hydrocyclones is therefore small. ~oreover, the risk of damage is reduced even further by providing the interior of the -~ hydrocyclones with a suitable protective l ming. The hydrocyclones are so econcmic because they separate very selectively. That is to say that relatively few fine particles enter the fraction with 25 intermediate slag particles. ~
; The fraction with inter~ediate particles is then dewatered.
For this purpose various types of separators are suitable. Suit-able types are dewatering screen units (the "Fordertechnik screen"
and the "Elliptexrdewaterizer", see L. Sv~rcvsky, Solid-liquid 0 separation, Butterworths, 1979, pp. 165-167). A number of diffe-rent filtration units and dewatering screws are also suitable.
~ Preferably, the fraction with the coarse particles is de-; ~latered by means of one or more dewatering rakes. These units are ~ the cheapest and most reliable. Moreover, during the dewatering ;~ 35 treatment a further separation is ef~ected between the entrained * Trade Mark . ~
,.
~L2~3~5 fine particles and intermediate particles. m e aqueous phase, which therefore still conta ms a ~ew, substantially f me, slag particles, is preferably recycled to the classify mg units, in particular the hydrocyclones. This ensures that no polluted water enters the environment.
The fraction with fine particles w~ich is discharged frc~ the classifying units is preferably passed to one or more settling basins. There concentration of the fine slag particles takes place. Preferably the concentrate is passed to one or m~re filter presses where further dewatering takes place.
m e sedi~entation rate of the fine particles in the settling basins is lcw, because the dImensions of the particles are so small. Particles of colloidal dimensions will even not settle at all. It is therefore preferred to add a flocculant to the frac~ion with fine particles. The addition of flocculant may be made in the settling basins but also upstream thereof. Because a considerable proportion of slag particles has already been separated from the suspension, a ccmparatively small quantity of flocc~lant is ; sufficient. Suitable flocculants are various cationic and/or anionic polymers.
The wat~r leaving the settling basins, name~y the averflow, is clear and contains fewer than 50 pFm slag particles in the water. This overflow can be discharged l:nto the surface water without any risk of environmEnt pollution. It can also, at least ;~25 partly, be recycled to the process and used as wash mg water and/or transport medium. The filtrate from the filter presses still contains a minor quantity of slag particles. Because it is desired to separate this minor quantity frcm the suspension as well~ the filtrate is preferably recycled to the settling basms.
The m~ention will now be further elucidated with reference to the Figure, to ~7hich the invention is hawever by no means lim~ted. Cc~ressors, valves,~control equip~nt etc. are not shawn :: in the dia~natic figure.
Via a line 1 an aquecus suspensiQn of slag particles is 35 p ssed to a static screen 2. There a fraction with coarse~pa~
:
: ~:
; '~
., ~
`
~391~
cles is separated and dewatered. The coarse particles are passed via a gutter 3 to a vibrating screen 5, where further dewatering takes place. The dewatered coarse slag particles are discharged from ~le syste~ by means of a gutter 7 and a con~eyor kelt 8. The separated water containing the intermediate and ~lne p2rticles is passed through a line 4 from the static screen 2 and through a line 6 from the vibrating screen 5 to a line 9~ From there it is passed via a line 10 to a hydrocyclone 11, where the separation between the intexmediate and fine particles takes place. A sus-p~nsion containing substantially intermediate particles leaves thecyclone through a line 12, which carries the suspension to a dewatering rake 14. In this dewatering unit the intermediate ;~ particles are separated from the suspension and removed from the system via a gutter 15 and a conveyor belt 16. T.he aqueous sus-pension with fine particles is passed via a line 17 into the line 9, so that the suspensi~n is recycled via the line lO into the hydrocyclone ll.
An aqueous suspension with fine slag particles lea~es the ; hydrocyclone 11 through a line 13. In the line 13 an aqueous : 20 solution of flocculant îs added to the suspension fru~ a vessel 25 .~: via a line 26. The aqueous suspension with the flocculant is passed via a line 18 into a settling basin l9. m ere thi ~ of the:suspension takes place. The ~hickened suspension is passed through the bottom of the settl mg basin 19 via a line 20 to a ~ 25 filter press 22. m e slag particles dewatered there are disch3rged : frcm the sysbem via a line 23. The filtrate from the filter press 22 is recycled via a line 24~to:the suspension m the line 13.
~: ~ The over low from the settling basin 19 is discharged via a line 21. A portion of the clarified water is passed via a line 27 : 30 t~ the vibrat mg screen 5 where it is used as washing water. The remainLng portion of the clarified water is discharged from the system via a l me 28.
lthcugh:they are not shown ln the Figure, it is possible to : incorpDrate a number of buf~er:vessels in the ~ethod according to the invention m order to co~nteract:fluctuations in the fe~d to 398~i continuously oFerating installations, or in order to serve as storage vessels for units operating batchwise. Suit-~ble locations for a buffer vessel are upstream of the hydrocyclone, between the h~drocyclone and the settling basin, and between the settling 5 basin and the filter press.
EX~LE
In a plant as diagrammatically shown in the Figure the following experiment was carried out.
Via the line 1, 34.886 kg/s of water with 1.438 kg/s of slag ; 1~ particles is supplied. After separation on the static screen 2, the c se slag particles are washed on the vibrating screen with 5.94 kg/s of water from the line 27. ~his produces a stream of coarse slag particles of 0.708 kg/s with 0.236 kg/s of water which is discharged via the gutter 7 and conveyor belt 8 for further 15 treatment.
The suspensions frcm the lines 4 and 6 are ccmbined in the line 9, through which 40.59 kg of water and 0.73 kg of slag particles flow per second. Via the line 17, 3.76 kg/s of wat~r with O.I88 kg/s of slag particles is added t~ the stream in the 20 line 9. After separation in the hydrocyclone 11, via~the;line 12 a quantity of 3.87 kg/s of water and 0.430 kg/s of slag is passed to the dewatering rake 14, where 0.242 kg/s of coarse sl~g particles with 0.110 kg/s of water is separated.
Via the stream in the line 13 of 40.48 kg/s of water and 25 0.488 kg/s of fine slag particles, to which via the line 24 an ; amount of 4.06 kg/s of water and 0.027 kg/s of slag is added, in addition to O.Ol kg/s ~f water and 0.0002 kg/s of flocculant via the l m e 26, via the line 18 a quantity of 44.55 kg/s of water and 0.515 kg/s of slag and 0.0002 kg/s of flocculant is supplied to 30 the settling basin 19. Via the line 20 a quantity~of 4.39 kg/s with 0.515~kg/s of sl g and 0.0002 kg/ of flocculant is supplied ~ to the filter press 22. ~ ~
-~ ~ There 0.4882 kg/s of solid matter with 0.330 kg/s of water is ~ separated. The filtrate is~recycled via the line 24.
, ~ ~
:
- ,, ,, ':
:
: - ~ , : . ;. : . ~:, .
-~2~398~i ~ 7 --From the settliny basin 19 a quantity of 40.16 kg/s of clearwater is discharged via the line 21. Of that quantity, 5.94 kg/s is passed to the vibrating screen 5 via the line 27, so that a quantit~ of 34.22 kg/s of water is discharged frcm the system via 5 the line 28.
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Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the dewatering of an aqueous suspension of slag particles obtained as a by-product in an ash-containing fuel-gasification process, comprising the steps of dividing the slag suspension into three fractions:
a) a first fraction with particles with a diameter larger than 1 mm:
b) a second fraction with particles with a diameter in the range from 0,06 to 1 mm;
c) a third fraction with particles with a diameter smaller than 0,06 mm, and dewatering each of the fractions separately.
a) a first fraction with particles with a diameter larger than 1 mm:
b) a second fraction with particles with a diameter in the range from 0,06 to 1 mm;
c) a third fraction with particles with a diameter smaller than 0,06 mm, and dewatering each of the fractions separately.
2. The method as claimed in claim 1 wherein the first fraction of particles is separated from the suspension and de-watered by means of one or more screen units.
3. The method as claimed in claim 1 or 2, wherein the first fraction of particles is separated from the suspension and dewatered by consecutively a static screen and a vibrating screen.
4. The method as claimed in claim 1, wherein the separation between the second fraction and the third fraction is effected by means of one or more hydrocyclones.
5. The method as claimed in claim 1, wherein the second fraction of particles is dewatered by means of one or more de-watering rakes.
6. The method as claimed in claim 1, wherein the separation between the second fraction and the third fraction is effected by one, or more, hydrocyclones; wherein the second fraction of particles is dewatered by means of one, or more, dewatering rakes; and wherein the aqueous phase from the dewatering of the second fraction is recycled from the dewatering rakes to the hydrocyclones.
7. The method as claimed in claim 1, wherein the third fraction of particles is concentrated in one or more settling basins and dewatered in one or more filter presses,
8. The method as claimed in claim 1 or 7, wherein a flocculant is added to the third fraction of particles.
9. The method as claimed in claim 7, wherein the filtrate is recycled from the filter presses to the settling basins.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8201454A NL8201454A (en) | 1982-04-06 | 1982-04-06 | METHOD FOR DEWATERING A SUSPENSION. |
| NL8201454 | 1982-04-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1243985A true CA1243985A (en) | 1988-11-01 |
Family
ID=19839539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000423841A Expired CA1243985A (en) | 1982-04-06 | 1983-03-17 | Particle size range separations prior to de-watering |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS58186413A (en) |
| AU (1) | AU557679B2 (en) |
| CA (1) | CA1243985A (en) |
| DE (1) | DE3312246A1 (en) |
| NL (1) | NL8201454A (en) |
| ZA (1) | ZA832393B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3533306A1 (en) * | 1985-09-18 | 1987-03-26 | Adolf Reiter | Process for separating and clear filtration of suspensions and apparatus therefor |
| US5082572A (en) * | 1990-09-05 | 1992-01-21 | Ogden Martin Systems, Inc. | Ash vibration process and apparatus |
| CN104162479A (en) * | 2014-06-12 | 2014-11-26 | 煤炭工业济南设计研究院有限公司 | Movable sieve waste rock discharge system slime water treatment process and device |
-
1982
- 1982-04-06 NL NL8201454A patent/NL8201454A/en not_active Application Discontinuation
-
1983
- 1983-03-15 AU AU12454/83A patent/AU557679B2/en not_active Ceased
- 1983-03-17 CA CA000423841A patent/CA1243985A/en not_active Expired
- 1983-04-05 JP JP58058807A patent/JPS58186413A/en active Pending
- 1983-04-05 ZA ZA832393A patent/ZA832393B/en unknown
- 1983-04-05 DE DE19833312246 patent/DE3312246A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE3312246A1 (en) | 1983-10-06 |
| AU1245483A (en) | 1983-10-13 |
| ZA832393B (en) | 1983-12-28 |
| AU557679B2 (en) | 1987-01-08 |
| JPS58186413A (en) | 1983-10-31 |
| NL8201454A (en) | 1983-11-01 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |