GB2041789A - Separating particles from a liquid - Google Patents
Separating particles from a liquid Download PDFInfo
- Publication number
- GB2041789A GB2041789A GB8003339A GB8003339A GB2041789A GB 2041789 A GB2041789 A GB 2041789A GB 8003339 A GB8003339 A GB 8003339A GB 8003339 A GB8003339 A GB 8003339A GB 2041789 A GB2041789 A GB 2041789A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquid
- bed
- particles
- chamber
- flow
- 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.)
- Granted
Links
- 239000002245 particle Substances 0.000 title claims abstract description 45
- 239000007788 liquid Substances 0.000 title claims abstract description 43
- 230000005294 ferromagnetic effect Effects 0.000 claims abstract description 7
- 239000006148 magnetic separator Substances 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims abstract description 5
- 239000011248 coating agent Substances 0.000 claims description 2
- 238000000576 coating method Methods 0.000 claims description 2
- 238000005260 corrosion Methods 0.000 claims 1
- 230000001681 protective effect Effects 0.000 claims 1
- 230000000717 retained effect Effects 0.000 description 9
- 238000005406 washing Methods 0.000 description 8
- 239000011159 matrix material Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000005291 magnetic effect Effects 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000006249 magnetic particle Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000011045 prefiltration Methods 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003758 nuclear fuel Substances 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 230000002000 scavenging effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/02—Magnetic separation acting directly on the substance being separated
- B03C1/025—High gradient magnetic separators
- B03C1/027—High gradient magnetic separators with reciprocating canisters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/06—Filters making use of electricity or magnetism
-
- 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
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C2201/00—Details of magnetic or electrostatic separation
- B03C2201/18—Magnetic separation whereby the particles are suspended in a liquid
Abstract
In a method and apparatus for separating particles suspended in a liquid from the liquid, a flow of the liquid is passed through a filter bed (7) of ferromagnetic bodies which acts as a coarse filter to trap the larger particles in the flow. The filter bed (7) is arranged within a truncated core between the poles of an electromagnet (9). To cleanse the bed and flush out the trapped particles a wash liquid is passed through the bed (7) and the electromagnet (9) is energised to levitate the bed to thereby allow the wash liquid to remove the particles. The liquid flow from the coarse filter can be passed to a high gradient magnetic separator (8) at which remaining small particles in the flow are filtered magnetically. <IMAGE>
Description
SPECIFICATION
Separating particles from a liquid
The present invention concerns the separation of particles from a liquid.
It is known to effect separation of particles suspended in a liquid by magnetic filtration. In such magnetic filters the liquid is passed through a chamber containing a bed of particles of magnetisable material. An electro-magnetic coil about the chamber is energised to magnetise the bed to thereby attract and retain the particles suspended in the liquid flow through the bed. After filtration, the trapped particles can be removed by isolating the electromagnetic coil and scavenging the chamber with a wash liquid whereby to agitate the bed and flush out the trapped particles.
The present invention seeks to provide a method and apparatus for filtering which enables the bed to be cleaned and flushed more quickly and with smaller quantities of wash liquid than hitherto.
According to one aspect of the present invention a method of separating particles comprises passing a flow of the liquid containing the particles through a filter bed of individual bodies, trapping the particles in the bed and then discontinuing the liquid flow, magnetically levitating the bed while passing a wash liquid flow therethrough to flush the particles out of the bed.
According to another aspect of the present invention apparatus for separating particles from a liquid comprises a chamber containing a filter bed of individual bodies, first flow path for passing the liquid through the chamber to trap the particles in the bed, second flow path for passing a wash liquid through the chamber, an electromagnet disposed outside the chamber and operable upon flow of the wash liquid to levitate the filter bed to thereby flush out the trapped particles.
The chamber is conveniently in the form of a truncated cone and the bodies may be supported on a mesh screen at the base of the chamber. A further electromagnet may be located so that the filter bed is located between its poles so that when the further electromagnet is energised magnetic particles are attracted to the ferromagnetic bodies and retained by them.
The bodies are preferably spherical and may be of iron or mild steel. When the liquid to be used is corrosive the bodies may be coated with a material which is inert to the liquid. For use with nitric acid the bodies may be coated with gold or platinum.
The apparatus may be used as a prefilter for a high gradient magnetic separator.
The invention will be illustrated by the following description of an assembly for removing solid particles from a liquid. The description is by way of example only and has reference to the single
Figure of the accompanying drawing which is a diagrammatic representation of the apparatus.
A liquid containing solid particles is placed in a tank 1 which has a stirrer 2 which keeps the solid particles in suspension. The liquid is fed from the tank 1 through a valve 3 to a filter 4 which comprises chamber 5 in the form of a truncated cone having a mesh screen 6 near its base on which is supported a filter bed of packed bodies 7 which are ferromagnetic and are preferably spherical in shape. The filter bed removes large particles from the liquid which then passes to a high gradient magnetic separator 8 in which smaller particles are magnetically filtered.
The chamber 5 is surrounded by an electromagnet 9 which is so placed that the mesh screen 6 is below the lower end of the pole gap and the filter bed extends upwards to about the centre of the pole gap. In normal use the electromagnet is not energised and particles which are too large pass between the packed bodies are retained by the filter. When it is desired to remove the retained particles from the filter bed valves 3 and 10 are closed and valves 11, 12, 13 opened to allow a supply of washing water to be passed through the filter bed. Energisation of the electromagnet causes the ferromagnetic bodies to be lifted away from the mesh 6 by the attraction of the magnetic field between the poles. As the bodies are lifted any particles retained by the filter bed are dislodged and may be removed by the washing water.The tapered chamber prevents the filter bed moving up as a plug and causes the bodies to move over one another as they are lifted. This relative movement of the bodies enables the retained particles to be flushed from the filter bed quickly with a small quantity of washing water . This is important in that it reduces the down time of the apparatus and in plant in which the particles being separated are radioactive it reduces the amount of radioactive liquid effluent which is produced during the washing of the filter bed. When the washing is complete the electromagnet is de-energised and the bodies fall back on to the mesh screen 6 under gravity to reform the filter bed.
The magnetic field required to levitate the bodies is in the order of 2000 Gauss when the bodies are spheres of 1/8 inch (3.18 millimetres) diameter and the chamber 5 has a mean diameter of 1 inches (32 millimetres). The bodies may conveniently be of iron or mild steel and may be provided with a protective coating to prevent attack on the bodies by the liquid containing the particles. In one application of the present invention the apparatus is used to remove undissolved particles from the liquid leaving a dissolver for irradiated nuclear fuel. This liquid has a high nitric acid content and so the bodies have to be protected by a coating of material which is resistant to nitric acid such as gold or platinum.
In the figure the washing water is shown flowing through the chamber 5 in the same direction as the liquid. If desired a reverse flow of washing water may be employed.
The solution leaving the filter bed 7 which has removed the larger particles from the solution then passes to the high gradient magnetic separator 8 where magnetic particles carried by the liquid are retained on a matrix of magnetic
material. In one embodiment the matrix comprises fine wires of a ferro-magnetic material. In this case the filter bed 7 acts as a prefilter to prevent the
large particles causing premature clogging of the
matrix. In a second embodiment the matrix within the magnetic separator comprises ferromagnetic
bodies similar in composition but conveniently smaller in diameter than those used for the filter bed 7. The bodies are normally located between the poles of a powerful electromagnet 14 so that any magnetic particles are attracted to and retained on the bodies by the magnetic field. The separator 8 may have a second electromagnet (not shown) which operates in a similar manner to that described hereinbefore to levitate the bodies to facilitate the cleaning of the matrix. This cleaning occurs when the electromagnet 14 is deenergised and the particles are no longer attracted to the bodies. In this second case the chamber in which the bodies are retained may be in the shape of a truncated cone.
To wash the magnetic separator 8 the magnet 14 is de-energised the valves 12 and 16 are closed and the valves 15, 10 and 13 are opened to allow washing water to wash through the matrix to remove particles which are no longer attracted to and retained by the bodies.
Claims (9)
1. A method of separating particles suspended in a liquid which comprises passing a flow of the liquid containing the particles through a filter bed of individual bodies, trapping the particles in the bed and then discontinuing the liquid flow, magnetically levitating the bed while passing a wash liquid flow therethrough to flush the particles out of the bed.
2. Apparatus for separating particles from a liquid comprising a chamber containing a filter bed of individual bodies, first flow path for passing the liquid through the chamber to trap the particles in the bed, second flow path for passing a wash liquid through the chamber, an electromagnet disposed outside the chamber and operable upon flow of the wash liquid to levitate the filter bed to thereby flush out the trapped particles.
3. An apparatus according to claim 2 in which the chamber comprises a truncated cone and the filter bed is supported on a screen at the base of the chamber.
4. An apparatus according to claim 3 in which the bed is arranged in the pole gap of the magnet and the magnet extends upwards beyond the bed.
5. An apparatus according to claim 2 in which the bed comprises ferromagnetic bodies.
6. An apparatus according to claim 5 in which a protective anti-corrosion coating is applied to the ferromagnetic bodies.
7. An apparatus according to claim 12 in which the first flow path includes a high gradient magnetic separator downstream from the chamber.
8. A method of separating particles suspended in a liquid substantially as herein described with reference to the accompanying drawing.
9. Apparatus for separating particles from a liquid substantially as herein described with reference to and as illustrated in the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8003339A GB2041789B (en) | 1979-02-02 | 1980-01-31 | Separating particles from a liquid |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7903800 | 1979-02-02 | ||
| GB8003339A GB2041789B (en) | 1979-02-02 | 1980-01-31 | Separating particles from a liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2041789A true GB2041789A (en) | 1980-09-17 |
| GB2041789B GB2041789B (en) | 1983-01-06 |
Family
ID=26270442
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8003339A Expired GB2041789B (en) | 1979-02-02 | 1980-01-31 | Separating particles from a liquid |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2041789B (en) |
-
1980
- 1980-01-31 GB GB8003339A patent/GB2041789B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2041789B (en) | 1983-01-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |