GB2061771A - Aids for diamond recovery - Google Patents

Abstract

The performance of a grease table or grease belt is tested and then adjusted by adding to gravel passing though a series of synthetic particles. Each such particle has a steel core encased in PTFE formed to octahedral shape. The synthetic particles are removed from the diamonds and the tailings by magnetic means.

Description

SPECIFICATION Aids for diamond recovery BACKGROUND OF THE INVENTION This invention relates to an aid for diamond recovery.

The grease table or grease belt method of diamond recovery is still widely used in preference to X-ray sorters. Operation of these tables or belts is still something of an art as performance checks can be made but irregularly and the feed-back from these checks can take up to 24 hours.

On the other hand an X-ray sorter can be set up using non-diamond tracer particles which luminesce at various intensities characteristic of the diamond particles found in the ore under treatment.

Obviously it would be of advantage to be able to set up or check the performance of a grease belt or table with the aid of tracer particles.

SUMMARY OF THE INVENTION According to the invention an aid to diamond recovery by means of a grease surface comprises a series of synthetic particles each of which has an outer surface which is hydrophobic to a similar extent to diamond, has a density approximating that of diamond and is shaped to simulate a diamond stone.

In the preferred form of the invention the outer surface is composed of a resinous material and preferably polytetrafluorethylene (PTFE) which is marginally more hydrophobic than diamond.

Also the density of each synthetic particle is preferably in the range of 3,3 to 3,7 while it is formed with at least one flat and tends to settle on that flat when rolled along a surface.

EXAMPLE A series of steel balls of varying diameter were chosen as cores for synthetic particles.

Each ball was encased in PTFE shaped to be an octahedral form. The nominal dimension of the particles was either 3mm, 6mm, 1 2mm or 30mm to correspond to different diamond concentrate sizes.

These particles were then used to set up or check a grease table by feeding a known number of them to a concentrate going to the table.

Note that the PTFE is acid and heat resistant so that no special precautions were taken.

The adhering particles can be removed from the grease surface by hand, noting their position, or will be collected in the concentrate by the knife on a grease belt. They can be recovered from the concentrate after degreasing by handsorting or magnetic separation since the other hydrophobic particles will be non-magnetic. The tracers lost to tailings, which indicate inefficiency in the unit, can be recovered from the tailings by magnetic separation, provided the magnetic mineral content of the tailings gravel is not too high. Otherwise these tracers can be retrieved by retreating the coilected tailings across a grease table at a reduced feed rate since the inert PTFE will retain its hydrophobic character in natural waters.

The operating variables such as the feed rate, water flow rate and grease blend can be adjusted conveniently to ensure that no, or an acceptably low number of, tracers are lost from the unit.

The tailings from the table were passed through a magnetic separator to recover PTFE coated particles which pass into the tailings.

The grease table parameters were then adjusted fairly quickly to ensure that no or only an acceptable number of PTFE particles report in the tailings.

1. An aid for diamond recovery by means of a grease surface comprising a series of synthetic particles each of which has an outer surface which is hydrophobic to a similar extent to diamond, has a density approximating that of diamond and is shaped to simulate a diamond stone.

2. The aid claimed in claim 1 in which the density of each synthetic particle is in the range of 3,3 to 3,7.

3. The aid claimed in either one of the above claims in which each synthetic particle is formed with at least one flat and tends to settle on that flat when rolled along a surface.

4. The aid claimed in any one of the above claims in which each synthetic particle has a core coated with a hydrophobic resinous material.

5. The aid claimed in claim 4 in which the material is PTFE.

6. An aid for diamond recovery by means of a grease surface substantially as herein described in the example.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Aids for diamond recovery BACKGROUND OF THE INVENTION This invention relates to an aid for diamond recovery. The grease table or grease belt method of diamond recovery is still widely used in preference to X-ray sorters. Operation of these tables or belts is still something of an art as performance checks can be made but irregularly and the feed-back from these checks can take up to 24 hours. On the other hand an X-ray sorter can be set up using non-diamond tracer particles which luminesce at various intensities characteristic of the diamond particles found in the ore under treatment. Obviously it would be of advantage to be able to set up or check the performance of a grease belt or table with the aid of tracer particles. SUMMARY OF THE INVENTION According to the invention an aid to diamond recovery by means of a grease surface comprises a series of synthetic particles each of which has an outer surface which is hydrophobic to a similar extent to diamond, has a density approximating that of diamond and is shaped to simulate a diamond stone. In the preferred form of the invention the outer surface is composed of a resinous material and preferably polytetrafluorethylene (PTFE) which is marginally more hydrophobic than diamond. Also the density of each synthetic particle is preferably in the range of 3,3 to 3,7 while it is formed with at least one flat and tends to settle on that flat when rolled along a surface. EXAMPLE A series of steel balls of varying diameter were chosen as cores for synthetic particles. Each ball was encased in PTFE shaped to be an octahedral form. The nominal dimension of the particles was either 3mm, 6mm, 1 2mm or 30mm to correspond to different diamond concentrate sizes. These particles were then used to set up or check a grease table by feeding a known number of them to a concentrate going to the table. Note that the PTFE is acid and heat resistant so that no special precautions were taken. The adhering particles can be removed from the grease surface by hand, noting their position, or will be collected in the concentrate by the knife on a grease belt. They can be recovered from the concentrate after degreasing by handsorting or magnetic separation since the other hydrophobic particles will be non-magnetic. The tracers lost to tailings, which indicate inefficiency in the unit, can be recovered from the tailings by magnetic separation, provided the magnetic mineral content of the tailings gravel is not too high. Otherwise these tracers can be retrieved by retreating the coilected tailings across a grease table at a reduced feed rate since the inert PTFE will retain its hydrophobic character in natural waters. The operating variables such as the feed rate, water flow rate and grease blend can be adjusted conveniently to ensure that no, or an acceptably low number of, tracers are lost from the unit. The tailings from the table were passed through a magnetic separator to recover PTFE coated particles which pass into the tailings. The grease table parameters were then adjusted fairly quickly to ensure that no or only an acceptable number of PTFE particles report in the tailings. CLAIMS

1. An aid for diamond recovery by means of a grease surface comprising a series of synthetic particles each of which has an outer surface which is hydrophobic to a similar extent to diamond, has a density approximating that of diamond and is shaped to simulate a diamond stone.

2. The aid claimed in claim 1 in which the density of each synthetic particle is in the range of 3,3 to 3,7.

3. The aid claimed in either one of the above claims in which each synthetic particle is formed with at least one flat and tends to settle on that flat when rolled along a surface.

4. The aid claimed in any one of the above claims in which each synthetic particle has a core coated with a hydrophobic resinous material.

5. The aid claimed in claim 4 in which the material is PTFE.

6. An aid for diamond recovery by means of a grease surface substantially as herein described in the example.