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Diamond Density Tracers & Applications

Description & Prices of Density Tracers for Diamond Applications
Standard Density Tracers (RD 2.50 – RD 3.53)

These tracers are available in 18 precise densities which are indicated by colour.
Density tracers with densities spanning the range of interest are added to the circuit feed and retrieved from the product and rejects streams, manually or with the assistance of magnets or X-ray sorters (see Applications). For statistical confidence, a test may utilize some thousands of tracers in selected sizes and densities. After retrieval they are sorted into their various densities, and the resulting data are used to plot a partition curve.
The form of the curve can indicate whether the metallurgist should take actions such as adjust medium density, replace a worn circuit component, or correct an overload or medium instability situation.

Colour Code

RD2.50

RD2.60

RD2.65

RD2.70

RD2.75

RD2.80

RD2.85

RD2.90

RD2.95

Light Pink

Lilac

Blue/Green

Grey

Dark Blue

Green

Apple Green

Cream

Light Blue

 

RD3.00

RD3.05

RD3.10

RD3.15

RD3.20

RD3.25

RD3.30

RD3.40

RD3.53

Orange

Lime Green

Dark Pink

Brown

Violet

Peach

Yellow

Black

Blue

Export Prices are in AUD (Australian Dollars)

Tracer=Size

1mm

2mm

3mm

4mm

5mm

6mm

8mm

10mm

12mm

16mm

20mm

Individual Price

$1.61

$1.83

$2.13

$2.51

$2.97

$3.51

$4.83

$6.47

$8.43

$13.31

$19.47

Min purchase Qty

100

100

100

100

100

100

100

50

50

25

25

Density Tracers for Diamond Applications offer the following:

  • Certified: Each shipment includes Quality Control Certificates for accuracy of density (100% within 0.02 g/cc of nominal density).

  • Discounts: 5% discount where 500 or more of the same item are ordered eg. 500 x 8mm RD 3.53.

  • Non Toxic: Contain no lead compounds.

  • Ferromagnetic: Are ferromagnetic to facilitate retrieval from plant streams or in the lab.

  • Luminescent: Luminesce under X-rays or UV to facilitate retrieval by X-ray sorters, or in the lab. Because they are opaque to visible light, tracers of this type in sizes 4mm or smaller may not be reliably recovered in sorters (such as Flowsort) configured such that the x-ray source and photomultiplier tube face different sides of the particle. Translucent Luminescence Index Tracers are designed for calibration and testing of all classes of X-ray sorters.

  • Fast Delivery: Common sizes couriered to your store in 1-2 weeks.

  • No Hidden Costs: Prices include packaging and handling.  Freight will be advised in an emailed quotation, where applicable.

  • Credit: For many clients we accept 30 day payment terms.

Diamond Density Tracers applications…
Density Tracer Testing

Tracer Size(s) and Retrieval
Tracer Densities
Number of Tracers
Conduct of the Test
Interpretation of DMC Partition Curves
References

The following procedures focus on dense medium cyclone circuits but are adaptable to other units. For a DMC circuit which has not previously been tested in this way, one must;

  • select appropriate size(s) of density tracers, while ensuring that they can be retrieved.
  • determine appropriate tracer densities to be employed.
  • determine the number of tracers to be used at each density interval.
  • assemble the required personnel and conduct the test.
  • assess the data.

Tracer Size(s) and Retrieval

To ensure relevance of the data to be generated, it is strongly recommended that tests be conducted with feed on. If using magnets for retrieval, one is usually free to select tracer sizes from 2mm up. If the nominal feed size range is, for example, -25+1mm, one may select tracers of 16, 8, 4 and 2mm. To check that retrieval rates are adequate, one may position the magnets at the discharge lips of the drain-and-rinse screens, then insert tracers of the relevant sizes at the feed ends of the screens. Retrieval rates commonly approach 100%, but reliable partition curves can be generated with retrieval rates as low as 70% (Wood, 2004).

If tracers are to be retrieved manually, it is usually feasible to employ only one size of tracer, which must be large enough to be reliably seen in the load on drain-and-rinse screens. For installations with a feed topsize in the 20-70mm range, 32mm tracers are most often used. For circuits with smaller feed it is sometimes possible to use 16mm tracers. At least one person must be positioned to retrieve tracers from each drain-and-rinse screen in the circuit, for the duration of the test.

Tracer Densities
Diamonds & Other Minerals

Density Tracers for diamond applications are offered in 18 densities ranging from 2.5 g/cc to 3.53 g/cc. The density intervals are 0.1 g/cc, or 0.05 g/cc in the region of the commonly-targeted cutpoint of about 3.1 g/cc. Metallurgists typically select from these about 10 densities which they find to be important to their operations. Cutpoints for nickel and iron ore processing are usually similar to those for diamonds.

Number of Tracers
Diamonds

With the larger density intervals in diamond circuit tests, it is common to use 100 tracers at each selected size and density. For a test using 3 sizes and 12 densities, the total number of tracers would be 3,600.

Conduct of the Test

If magnets are used, they should be positioned in the drain-and–rinse launders, but just out of the ore streams. After conducting any preliminary observations such as determinations of the densities of feed, overflow and underflow media, drop the selected tracers into the circuit feed, typically into a deslime screen oversize launder.
Slide the magnets into their respective floats and sinks streams before arrival of the first tracers.
5 minutes after addition of the tracers, slide the magnets out of their streams. Any tracers not retrieved are considered as lost, or retained in the separator. If necessary, gently hose ore particles off the magnet, then pick off the tracers for washing, sorting into size and density fractions and counting. In cases where products from individual cyclones in a module are drained on separate screens, it can be helpful to separately record the tracers which report to those screens. A separate sheet may be used for each tracer size.
Enter the numbers in the floats and sinks columns of appropriate test sheets (Test Data Sheet) If tracers are to be retrieved manually, they should be inserted at a rate suitable for manual retrieval, around one tracer every two-three seconds.

Interpretation of DMC Partition Curves.

The figures below illustrate the common forms of density tracer partition curves for dense medium cyclones. A module of one or more well-operated and well maintained dense medium cyclones should show an efficient separation (Figure 1). By contrast with conventional float/sink techniques, density tracers provide the resolution which shows that large particles can be partitioned with an Ep of less than 0.01 RD units.

Interpretation-of-DMC-Partition-Curves

Fig. 1 Normal (efficient) partition curve.
Figure 2 shows a reasonably small RD range of particle retention. Separation is still quite efficient but there is a danger that a small change in operating conditions may increase the density range of retention. The cyclones rapidly.

become choked with "near-density" material and frequently clear themselves by ejecting surges of slurry, including low-density coal, to underflow.

Interpretation-of-DMC-Partition-Curves-2

 

Fig. 2 Tracer Retention
The resulting partition curve is shown in Figure 3. The Ep is large; there is a low-density "tail" and a low (sometimes negative) offset between feed medium density and cutpoint. The performance shown in Figure 3 can also arise from vortex finder overload when the medium flow from the vortex finder is insufficient to carry out all the particles which should report to the low-density product. As with surging, the yield loss can be very significant.

Interpretation-of-DMC-Partition-Curves-3

 

Fig. 3 Surging or Vortex Finder Overload can cause yield loss.
A curve with a plateau (Figure 4) is indicative of differing cutpoints between separators in the module. Examination of the data for individual product screens will suggest which units are separating at high, and which at low density.

Interpretation-of-DMC-Partition-Curves-4

Fig. 4 Two DMCs with different cutpoints.
Means for the correction of these separating inefficiencies may be found in the references listed below or by contacting Partition Enterprises Pty Ltd.

References

Davis, JJ, Wood, CJ and Lyman, GJ, 1985a, "Density Tracers Can Improve Coal Preparation Plant Yield", Australian Coal Miner, July, pp9-1 1.
Davis, JJ, Wood, CJ and Lyman, GJ, 1985b, "The Use of Density Tracers for the Determination of Dense Medium Cyclone Partitioning Characteristics", Int. J. of Coal Processing, 2(2) 107-126.
Davis, JJ, Wood, CJ and Lyman, GJ, 1985c, "The Effects of Operating Variables on Dense Medium Cyclone Operation", Proceedings, Third Australian Coal Preparation Conference, Wollongong.
Wood CJ, Davis, JJ and Lyman, GJ, 1987, "Towards a Medium Behavior Based Model for Coal-Washing Dense Medium Cyclones", Aus IMM Dense Medium Operators' Conference, Brisbane, 1987, pp247-256 and Coal Preparation, 1989, Vol 7, ppl83-197.
Wood, C.J., 2004. “Density Tracer Testing of Coarse Coal Separators: Suggestions for an Australian Standard", in Membrey, WB(ed), Proceedings, Tenth Australian Coal Preparation Conference, Paper E12.

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