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ODM Heavy Mineral Separation (<1 mm fraction)



Overburden Drilling Management, heavy mineral separation, <1 mm fraction.

General Methodology:

Overburden Drilling Management indicator mineral grain separation. The sample is split into several size and magnetic fractions as a precursor to mineral grain identification. This procedure is slightly different than the standard ODM flow chart. (how, exactly?)

A +/-10 kg split from the bulk sample is disaggregated and screened with a 2 mm and 1 mm mesh respectively.  The < 1 mm fraction is pre-concentrated with respect to density using a shaker table.  Samples are run twice through the shaking table and the concentrates are then panned, and gold grains are picked and counted.  The table concentrate is then put through methylene iodide diluted with acetone (specific gravity of 3.2) and the heavy mineral concentrate (HMC) is collected.  The HMC is ferromagnetically separated and the non-ferromagnetic heavy mineral concentrate (NFM-HMC) is screened to recover the 0.25-0.50 mm and 0.5-1.0 mm fractions.  Samples with abundant indicator minerals in the < 1mm fraction are processed for heavy mineral concentrates directly by using diluted methylene iodide.  Numerous weights are recorded during the procedure, as listed in the table below:

1 Amount processed (kg)
2 Oversize clasts (>2 mm) (kg)
3 Wet sieve (1 and 2 mm)
4 Table feed shaker sample run twice
5 < 1 mm table concentrate total (g) (not reported in Open File 3079-but should equal rows 6 + 7)
6 < 1 mm table concentrate methylene iodide (M.I.) separation-M.I. light fraction (g)
7

< 1 mm table concentrate methylene iodide (M.I.) separation -M.I. heavy fraction (g)

(should equal sum of rows 8 + 12)

8

< 1 mm methylene iodide (M.I.) heavy fraction non-ferromagnetic fraction total (g)

(should equal sum of rows 9 + 10 + 11)

9 < 1 mm M.I. heavy fraction non-ferromagnetic processed split < 0.25 m (g)
10 < 1 mm M.I. heavy fraction non-ferromagnetic processed split 0.25-0.5 mm (g)
11 < 1 mm M.I. heavy fraction non-ferromagnetic processed split 0.5-1 mm (g)
12 < 1 mm M.I. heavy fraction ferromagnetic processed split (g)
13 1 - 2 mm table concentrate methylene iodide (M.I.) separation -M.I. heavy fraction (only for samples that had abundant indicator minerals in the < 1 mm fraction) (g)

(Description taken from GSC Open File 3079 (1993 samples), page 8; see also the flow chart in this Open file on page 10)

Instrument: unstated

Sample material: solid

Sample weight: unstated


Analytical Technique:

Hierarchical classification

Technique >> Physical techniques >> Mineral grain separation

Children

None


Analytical Decomposition:

Hierarchical classification

Decomposition >> None

Children

None


Analytical Methods:

IndexMethod OrderMethod IDQuantityDetection Limit
1  6043     Wt_Processed 
2  6044     Wt_OvrSize 
3  6045     Wt_100_200 
4  6046     Wt_TblFeed 
5  6047     Wt_TblConc 
6  6048     Wt_MI_Lght 
7  6049     Wt_MI_Hvy 
8  6050     Wt_MI_NFM_Tot 
9  6051     Wt_MI_NFM_lt25 
10  10  6052     Wt_MI_NFM_25_50 
11  11  6053     Wt_MI_NFM_50_100 
12  12  6054     Wt_MI_FM 
13  13  6055     Wt_MI_100_200 

Associated Analytical Packages:

IndexPackage IDPackage Name
1  165     ODM heavy mineral separation and VG counts (<1 mm fraction table processed; 1-2 mm fraction processed by methylene iodide)
2  172     ODM heavy mineral separation (<1 mm fraction table processed; 1-2 mm fraction processed by methylene iodide)
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