Processing of the first section of the 37840 cubic metre bulk
sample of basal gravels from the south channel, bulk sample site
1, of the company’s Sunda Shelf diamond exploration project in southeast Kalimantan, Indonesia, has begun.
The plant is currently processing the first 2360 cubic metres of
gravels from sub-sample 1A. This should be completed during the
next few days with results of diamond recovery expected to follow
shortly after.
The 30 cubic metre per hour jig plant and Wolf X-ray diamond
recovery machine have been commissioned with sandy gravels dug
from a barren area immediately prior to the commencement of the
main sample. It is planned to double the capacity of the plant
during the next two months.
Large gravels of up to 15cm in diameter – an encouraging indicator
for the presence of diamonds – have been mined in the first
section of the sample.
Details of the sample program follow.
South Channel Sample – Line 2000 West (Site 1)
The sample of 37,840 cubic metres of gravels is being mined on
line 2000 west, between 1835 south and 1550 south. It will be
extracted and processed in five sub-samples and should be completed
by the end of January.
Trench
Length Gravel Overburden
Sub- at bedrock Volumes volume
Sample (m) (cubic m) (cubic m)
—— ———- ——— ———-
1A 25 2,360 38,600
1B 90 14,400 89,900
1C 60 7,460 60,000
1D 80 11,100 80,000
1E 30 2,520 30,000
Maximum basement depth over the length of the channel is 35.5
metres below sea level. This is within the digging reach of the
Aokam Thai No 3 dredge.
Sub-Sample 1A
The dredge removed 36,000 cubic metres of mud and
clay to reach the target area at 30 metres below sea level. It
then stripped overburden of 38,600 cubic metres to
expose the gravel surface area of 25 metres by 25 metres. The
gravel thickness of the first sub-sample is 4 metres
and the volume to be mined and processed is 2,360 cubic metres.
All gravels in the minus 18mm size fraction are being processed
through the jig plant. The final diamondiferous concentrate is
processed by a Wolf X-ray diamond recovery machine. Tailings from
the X-ray recovery will be processed by Plietz jigs to recover
heavy minerals and audit the efficiency of the X-ray process. The
screens of the jig plant are set to process gravels in the minus
18mm range which will allow all diamonds up to 60 carats in size
to be recovered. The jig baskets will be removed progressively
over the next few days to enable the concentrate to be processed
by the X- ray machine. Results of diamond recovery from
sub-sample 1A will be released as soon as available. This is
expected to be by the end of the first week of December.
The gold, platinum and heavy mineral concentrates will be
processed at the onshore laboratory of the project’s exploration
manager, P.T. Indo Mineratama.
The sub-sample 1A gravels are of a favourable size with oversize
of up to 15cm in diameter, indicating sufficient energy having
been active within the palaeochannel system to have transported
diamonds to the present location. This is further supported by
the presence of gold and rutile – key regional indicators for
diamonds – in the commissioning sample.
Sub-Samples 1B to 1E
These samples will be mined and processed during the next two
months and results will be announced progressively.
The sites of three further samples have been selected and each
will be infill drilled prior to sampling.
