Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Patent
1993-11-05
1996-04-09
Dayoan, D. Glenn
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
209587, 209589, 356 30, B07C 500
Patent
active
055053130
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to classifying or sorting objects, for instance for sorting ore from associated mineral material or sorting diamonds from gangue in the diamond mining industry.
Diamonds can be mined from deposits in rock and in this process it is necessary to crush the rock and then sort the diamonds from the gangue or unwanted material. A process for achieving a primary sort of gangue from diamonds is disclosed in European Patent Application No. EP-A-0 345 949 filed by the Applicants. In this process mixed diamonds and gangue are fed on a broad belt feeder, a narrow transverse strip of which is irradiated by X-rays or visible radiation, the fluorescence or Raman emission of diamond being detected to give a signal and locate the diamond. This signal actuates means for selecting diamonds from the stream of mixed material and directing them to a bin to give a diamond rich concentrate. However, other non-diamond mineral particles also fluoresce under the X-ray irradiation or exhibit broad band luminescence stimulated by the excitation source, e.g. a laser operating in the UV/visible portion of the spectrum. This laser excited broad band luminescence covers the region that is specifically examined for detecting the characteristic Raman shift for diamond. This broad band laser induced luminescence is falsely identified as a Raman shifted response and thus other mineral particles can be falsely identified and selected as diamond. Additionally, as this primary sorter is a high-mass sorter, the diamond and gangue mixture is fed on a wide belt and the diamond selecting means may select the particles sitting next to the fluorescing particle on the belt as well. Thus the machine can only produce a diamond/luminescing mineral/gangue concentrate. Traditionally this concentrate is hand sorted which is laborious, and as some of the minerals are fairly similar in appearance to the diamonds, can be difficult and unreliable.
In addition to the primary sort achieved by this type of machine, it is necessary to provide a machine for achieving a more accurate sort on the concentrate produced by the process, and remove the other non-diamond material collected in the primary process.
Methods of classifying diamonds by studying them with radiation are generally known (for example EP-A-0345949 as above) but it is desirable to provide a method of classifying diamonds and other objects using radiation in which the problem of the varying trajectories obtained with objects of different sizes and shapes without expensive object projecting means is avoided.
THE INVENTION
A first aspect of the invention provides a method and apparatus for classifying an object.
The objects may be irradiated in a zone which is of sufficient extent to intersect the trajectories of all objects, which may have different trajectories due to differing size and shape, the irradiation zone being such that the local radiation intensity is enough to cause substantial excitation of objects of interest. However, the irradiation zone should be as small as is practical, so that the power input required to achieve the necessary radiation intensity is not too high. This sufficient intensity of radiation may be achieved by focussing a beam of irradiating radiation onto a relatively small area, for example a line focus. Where a focus is used, the irradiation zone will correspond to the region at the focus. Where the irradiation zone is much longer than it is wide, it is substantially linear. The irradiation zone is preferably defined by a section of a straight line, but it could be slightly curved. The exact shape of the irradiation zone in said substantially vertical plane need not be of any specific shape-it could be ellipsoid, retangular, triangular etc.
In the present application, a beam of light is considered to be focussed if it is brought to a focus in a first plane, even if it is not brought to a focus in a second plane at right angles to the first plane.
Often, objects fall at different rates due to differing size and shape.
REFERENCES:
patent: 4799786 (1989-01-01), Gerrard
patent: 4875771 (1989-10-01), Bowlely et al.
patent: 4900147 (1990-02-01), Bowlely et al.
patent: 4919533 (1990-04-01), Bowley et al.
patent: 5118181 (1992-06-01), Yifrach et al.
patent: 5143224 (1992-09-01), Burchell
patent: 5206699 (1993-04-01), Stewart et al.
patent: 5351117 (1994-09-01), Stewart et al.
Smith Martin P.
Smith Robin W.
Dayoan D. Glenn
Gersan Establishment
LandOfFree
Method and apparatus for detecting diamonds in a plurality of ob does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for detecting diamonds in a plurality of ob, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for detecting diamonds in a plurality of ob will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-133402