Keywords

HMC separation (ODM standard)



Keyword Definition

Overburden Drilling Management indicator mineral grain separation.  The sample is separated into several size and magnetic fractions, as a precursor to mineral grain identification.  The procedure described here corresponds to the standard ODM flow chart.  See Figure 6 in GSC OF 3081.

The sample is disaggregated and screened with a 2mm mesh.  The <2 mm fraction is pre-concentrated with respect to density using a shaker table.  The table concentrate is then put through diluted methylene iodide (specific gravity of 3.2) and the heavy mineral concentrate is collected.  After a ferromagnetic separation, the nonferromagnetic heavy mineral concentrate (NFM-HMC) is screened to recover the 0.25-0.50 mm, 0.5-1mm and 1-2mm fractions for indicator mineral picking.  Numerous weights are recorded during the procedure, as listed in the table below:

1 Bulk received (kg)
2

Table split (kg)

(usually 0.5 kg less than the bulk received)

3 Oversize clasts ( > 2 mm) (kg)
4 Table feed
5

< 2 mm table concentrate total (g)

(should equal the sum of rows 6 + 7 + 8)

6 < 2 mm table concentrate heavy liquid separation – heavy liquid lights (g)
7 < 2 mm table concentrate heavy liquid separation – magnetic HMC (g)
8 < 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC total (g)
9

< 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC processed split total (g)

(usually equal to row 8)

(should equal the sum of rows 10 + 11 + 12 + 13 + 14)

10 < 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC processed split – < 0.25 mm (wash) (g)
11 < 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC processed split – < 0.25 mm (g)
12 < 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC processed split – 0.25 to 0.5 mm (g)
13 < 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC processed split – 0.5 to 1 mm (g)
14 < 2 mm table concentrate heavy liquid separation – non-ferromagnetic HMC processed split – 1.0 to 2.0 mm (g)

There are numerous variations to this technique.  Possible variations include:

  • the non-ferromagnetic fraction may be further separated, based on paramagnetism
  • samples may be run once or twice over the shaker table, and material from the different runs may be kept separate
  • the bulk sample may be screened with a 1mm mesh (not 2mm)

 



Category: Sample preparation procedures

Keywords corresponding to sample preparation procedures. Taken from the “Sample_Preparation_Methodss_SHARED” database table.


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