GB2229116A - Sorting particles of differing thermal conductivities - Google Patents
Sorting particles of differing thermal conductivities Download PDFInfo
- Publication number
- GB2229116A GB2229116A GB9003803A GB9003803A GB2229116A GB 2229116 A GB2229116 A GB 2229116A GB 9003803 A GB9003803 A GB 9003803A GB 9003803 A GB9003803 A GB 9003803A GB 2229116 A GB2229116 A GB 2229116A
- Authority
- GB
- United Kingdom
- Prior art keywords
- particles
- time period
- drum
- adhered
- diamondiferous
- 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 70
- 239000007788 liquid Substances 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 18
- 230000008014 freezing Effects 0.000 claims abstract description 12
- 238000007710 freezing Methods 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000009736 wetting Methods 0.000 claims description 2
- 238000012423 maintenance Methods 0.000 claims 1
- 239000011236 particulate material Substances 0.000 claims 1
- 239000010432 diamond Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 229910003460 diamond Inorganic materials 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000000155 melt Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B13/00—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices
- B07B13/003—Separation of articles by differences in their geometrical form or by difference in their physical properties, e.g. elasticity, compressibility, hardness
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
Abstract
The particles are wetted with a liquid such as water, and the wetted particles brought into contact with a surface (14) which is at a temperature at or below the freezing point of the liquid. After a specified time period, particles which do and which do not adhere to the surface as a result of freezing effects are separately recovered from the surface, for example in bins (24, 26) separated by a divider (28). The method is particularly useful for separating diamondiferous from non-diamondiferous particles. <IMAGE>
Description
SORTING APPARATUS AND APPARATUS
BACKGROUND TO THE INVENTION
THIS invention relates to a sorting method and apparatus. In one application of the invention, it may be used to sort diamondiferous particles from non-diamondiferous particles.
It is known that diamonds have a much higher thermal conductivity than the non-diamondiferous material with which they are normally associated in the natural enviroment. The invention seeks to use such differences in thermal properties in a method and apparatus of sorting particles.
SUMMARY OF THE INVENTION
According to the invention there is provided a method of sorting particles having different thermal conductivities into fractions, the method comprising wetting the particles with a liquid, bringing the particles into contact with a surface which has a temperature at or below the freezing point of the liquid, and separately recovering from the surface particles which are and are not adhered to the surface after a specified time period.
The method is time and temperature dependent. These parameters may, on the one hand, be set such that during the specified time period, all particles adhere to the surface by reason of the liquid with which they are wetted freezing, those particles having a higher coefficient of thermal conductivity releasing heat rapidly enough to melt the frozen liquid with the result that they are released from the surface by the end of the specified time period, while other particles having a lower coefficient of thermal conductivity are not able to release heat rapidly enough to melt the frozen liquid by the end of the specified time period and thus remain adhered to the surface.
On the other hand, the time parameters may be set such that the particles with the higher coefficient of thermal conductivity lose heat more rapidly to prevent freezing of the liquid, such particles thus not adhering at all to the surface, while the other particles with the lower coefficient of thermal conductivity do not lose sufficient heat within the specified time period to prevent freezing of the liquid and thus are adhered to the surface when the liquid does freeze.
The method may, in one example, be used to sort diamondiferous material from non-diamondiferous material, diamond having a higher coefficient of thermal conductivity than the gangue material with which it is normally associated. In this case, the separation of the particles into fractions may take place after a time period sufficient for the diamond particles to melt the frozen liquid and be released from the surface.
The invention also provides apparatus for use in the method, the apparatus comprising a surface which can be maintained at a temperature at or below the freezing point of a liquid with which particles to be sorted have previously been wetted, means for bringing the particles into contact with the surface, and means for separately recovering from the surface, after a specified time period, particles which are and are not adhered to the surface.
The liquid which is used may be water, in which case the surface, possibly the cylindrical surface of a drum rotating about a horizontal axis, is at a temperature of OOC or less.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawing which illustrates the method and apparatus of the invention schematically.
SPECIFIC DESCRIPTION
In the drawing, a drum 10 rotates about a horizontal axis 12 and has a round cylindrical surface 14. The drum is internally cooled such that the surface 14 has a temperature of OOC or less. Particles 16 to be sorted, in this case diamondiferous particles 18 and non-diamondiferous gangue particles 20, are at ambient temperature and are fed by a chute 22 onto the moving surface of the drum. Prior to this, all the particles are wetted with water.
By the term "diamondiferous particles" is meant particles which are either pure diamonds or particles which have a relatively high diamond content, say 50% or more.
Soon after the particles contact the cold surface 14 of the drum, the water with which they are wetted freezes. The freezing of the water results in the particles adhering to the surface 14.
The diamondiferous particles 18, having a higher coefficient of thermal conductivity than the gangue particles 2Q, are able to lose more heat more quickly to the ice which adheres them to the surface 14. Thus the ice adhering the diamondiferous particles melts more quickly than the ice adhering the non-diamondiferous particles. This in turn means that the diamondiferous particles are released from the surface of the drum more quickly than the gangue particles and are the first to fall off the drum under gravity. The particles which are the first to fall off the drum collect in a bin 24 while particles which fall off subsequently collect in a bin 26. A splitter plate 28 ensures efficient separation of the particles into the relevant fractions.
In this embodiment, the non-diamondiferous particles, which adhere to the surface 14 for the longer period of time, fall off under gravity. It may in some cases be preferable to physically remove the adhering particles, for example with a hot air blast or with a scraper or the like.
It will be appreciated that the method described above is time and temperature dependent. In the specific example given above, these parameters are set such that the diamondiferous particles are not stuck to the surface of the drum at the end of a specified time period, while non-diamondiferous particles are. In other examples of the invention, different parameters may be used. For instance, the parameters may be such that diamondiferous particles lose heat so rapidly that they prevent any freezing of the liquid by the time separation of the particles is to take place while non-diamondiferous particles do not lose sufficient heat in this period of time to prevent freezing of the liquid.
A further possibility would be that the diamondiferous particles lose heat to melt the liquid and then retain insufficient heat to prevent refreezing of the liquid, with the result that these particles are adhered to the surface at a specified time. The non-diamondiferous particles, on the other hand, lose heat to melt the liquid, but still retain sufficient heat to prevent refreezing of the liquid.
The invention is not confined to sorting diamondiferous from non-diamondiferous particles. Particles having different thermal conductivities may be sorted into a number of fractions on the basis of their different thermal conductivities, using the method and apparatus of the invention.
Claims (14)
1.
A method of sorting particles having different thermal conductivities into fractions, the method comprising wetting the particles with a liquid, bringing the particles into contact with a surface which has a temperature at or below the freezing point of the liquid, and separately recovering from the surface particles which are and are not adhered to the surface after a specified time period.
2.
A method according to claim 1 wherein the temperature of the surface and the time period are set such that particles with a higher thermal conductivity are not adhered to the surface at the end of the time period while particles with a lower thermal conductivity are adhered to the surface at the end of the time period.
3.
A method according to claim 1 wherein the temperature of the surface and the time period are set such that particles with a lower thermal conductivity are adhered to the surface at the end of the time period while particles with a lower thermal conductivity are not adhered to the surface at the end of the time period.
4.
A method according to any one of the preceding claims when used to sort particulate material into diamondiferous and non-diamondiferous fractions.
5.
A method according to any one of the preceding claims wherein adhering particles are recovered from the surface by means of a hot air blast or by means of a scraper.
6.
Apparatus for sorting particles having different thermal conductivities into fractions, the apparatus comprising a surface, means for maintaining the surface at a temperature at or below the freezing point of a liquid with which particles to be sorted have previously been wetted, means for bringing the wetted particles to be sorted into contact with the surface, and means for separately recovering from the surface, after a specified time period, particles which are and are not adhered to the surface.
7.
Apparatus according to claim 6 in which the liquid is water and wherein the temperature maintenance means operate to maintain the surface at a temperature of 0 or less.
8.
Apparatus according to either one of claims 6 or 7 wherein the surface is the cylindrical surface of a drum rotatable about a horizontal axis.
9.
Apparatus according to claim 8 wherein the drum is internally cooled.
10.
Apparatus according to either one of claims 8 or 9 and comprising a chute for feeding wetted particles to be sorted onto the cylindrical surface of the drum.
11.
Apparatus according to claim 10 and comprising first and second bins located beneath the drum for collecting particles which are not adhered to the surface of the drum at the end of the time period and which fall off the surface of the drum, and for collecting particles which are adhered to the surface of the drum at the end of the time period and which are subsequently caused or allowed to fall off the surface of the drum.
12.
Apparatus according to any one of claims 6 to 12 when used to sort diamondiferous and non-diamondiferous particles into fractions.
13.
A sorting method substantially as herein described with reference to the accompanying drawings.
14.
A sorting apparatus substantially as herein described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA891301 | 1989-02-20 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9003803D0 GB9003803D0 (en) | 1990-04-18 |
| GB2229116A true GB2229116A (en) | 1990-09-19 |
| GB2229116B GB2229116B (en) | 1992-12-02 |
Family
ID=25579608
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9003803A Expired - Lifetime GB2229116B (en) | 1989-02-20 | 1990-02-20 | Particle sorting method and apparatus |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU628133B2 (en) |
| GB (1) | GB2229116B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2247195A (en) * | 1990-07-06 | 1992-02-26 | De Beers Ind Diamond | Sorting particles |
| GB2269549A (en) * | 1992-08-11 | 1994-02-16 | De Beers Ind Diamond | Method of sorting particulate material |
| WO1994011125A1 (en) * | 1992-11-17 | 1994-05-26 | Stork Protecton B.V. | A method and device for separating components from a composite quantity of material |
| DE4301987A1 (en) * | 1993-01-26 | 1994-07-28 | Soelter Nikolai | Apparatus and method for determining the specific heat capacity by means of a heat pulse and at the same time determining the temperature conductivity |
| US6585455B1 (en) | 1992-08-18 | 2003-07-01 | Shell Oil Company | Rocker arm marine tensioning system |
| EP2343136A4 (en) * | 2008-10-28 | 2012-09-19 | Panasonic Corp | SORTING PROCESS |
| US10562075B2 (en) | 2014-12-05 | 2020-02-18 | Urban Mining Corp B.V. | Sensor separation apparatus and method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2184043A (en) * | 1985-12-11 | 1987-06-17 | De Beers Ind Diamond | Separation of particles having different heat capacities and coefficients of thermal conductivity |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU576289B2 (en) * | 1985-04-09 | 1988-08-18 | De Beers Industrial Diamond Division (Proprietary) Limited | Separation of diamonds from diamond bearing material |
| AU612535B2 (en) * | 1989-01-19 | 1991-07-11 | De Beers Industrial Diamond Division (Proprietary) Limited | The formation of an ice sheet and the use thereof in sorting |
-
1990
- 1990-02-20 AU AU49999/90A patent/AU628133B2/en not_active Ceased
- 1990-02-20 GB GB9003803A patent/GB2229116B/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2184043A (en) * | 1985-12-11 | 1987-06-17 | De Beers Ind Diamond | Separation of particles having different heat capacities and coefficients of thermal conductivity |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2247195A (en) * | 1990-07-06 | 1992-02-26 | De Beers Ind Diamond | Sorting particles |
| AU632947B2 (en) * | 1990-07-06 | 1993-01-14 | De Beers Industrial Diamond Division (Proprietary) Limited | Sorting method and apparatus |
| GB2247195B (en) * | 1990-07-06 | 1994-01-12 | De Beers Ind Diamond | Sorting method |
| AU654780B2 (en) * | 1992-08-11 | 1994-11-17 | De Beers Industrial Diamond Division (Proprietary) Limited | Particle sorting method |
| GB2269549A (en) * | 1992-08-11 | 1994-02-16 | De Beers Ind Diamond | Method of sorting particulate material |
| GB2269549B (en) * | 1992-08-11 | 1995-08-23 | De Beers Ind Diamond | Method of sorting particulate material |
| US6585455B1 (en) | 1992-08-18 | 2003-07-01 | Shell Oil Company | Rocker arm marine tensioning system |
| WO1994011125A1 (en) * | 1992-11-17 | 1994-05-26 | Stork Protecton B.V. | A method and device for separating components from a composite quantity of material |
| DE4301987A1 (en) * | 1993-01-26 | 1994-07-28 | Soelter Nikolai | Apparatus and method for determining the specific heat capacity by means of a heat pulse and at the same time determining the temperature conductivity |
| EP2343136A4 (en) * | 2008-10-28 | 2012-09-19 | Panasonic Corp | SORTING PROCESS |
| US8398861B2 (en) | 2008-10-28 | 2013-03-19 | Panasonic Corporation | Separation method |
| US10562075B2 (en) | 2014-12-05 | 2020-02-18 | Urban Mining Corp B.V. | Sensor separation apparatus and method |
| US11458508B2 (en) | 2014-12-05 | 2022-10-04 | Urban Mining Corp B.V. | Sensor separation apparatus and method |
Also Published As
| Publication number | Publication date |
|---|---|
| AU4999990A (en) | 1990-08-23 |
| GB9003803D0 (en) | 1990-04-18 |
| AU628133B2 (en) | 1992-09-10 |
| GB2229116B (en) | 1992-12-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20010220 |