DML Resources Limited - Mining Division produced over 50 000 oz of alluvial
gold in the 1995 - 1996 year from five operations located in the West Coast and
Otago Regions on the South Island of New Zealand.
DML Resources Limited - Mining Division have a twenty year history of
alluvial gold mining development in New Zealand. Recent expansions have seen the
establishment of two operations in Chile whilst exploration continues in
Bolivia, Peru and Argentina. The overseas growth is based on a stable production
base in New Zealand focussed on the West Coast and Southland/Otago present and
future operations. DML Resources consider that the mining potential in the
Arahura Valley on the West coast will be fundamental to their New Zealand
operations for some time. Collectively the plants operating in this catchment
are referred to as the Poutini Project.
Recent and late Pleistocene gravels derived from the erosion of the Alpine
Schists running parallel to the Alpine Fault located on the Pacific/Australian
Plant boundary are thought to be the sources of the alluvial gold in the Arahura
and adjacent catchments. These gravels have been extensively mined for the past
130 years yielding some six million ounces over this period. Production from the
Poutini Project started in 1989 and stood at approximately 35 000 oz for the
1995 - 1996 year. This production was split among three plants each working
different areas of the deposit. Recovery techniques from each of the plants are
fundamentally the same. Gravels are fed to a floating treatment plant where,
following screening, the gold is recovered using jig plants and knudsen bowls.
Overburden to wash stripping ratios vary between zero and seven to one with
plants treating between 80 and 250 cubic metres per hour. Restoration of the
land following mining is undertaken progressively. All land in the Poutini
Project area mined to date has been restored to a standard suitable for dairy
farming purposes.
The Poutini Project is a cooperative venture between the Maori landowners and
DML Resources Ltd. The Arahura River has particular cultural significance to the
Maori as it is the source of the much valued greenstone or pounamu a type of
jade valued for jewellery and tools. The Poutini Agreement was signed in 1989
setting out the role of each party in the mining of the Arahura and adjacent
lands.
Current exploration and development should extend the resource to allow
mining to continue on the Poutini project for an additional three to five years
at current gold prices. Production within new Zealand beyond this point may be
compromised by increasing difficulty in gaining access to prospective areas
within New Zealand, lowered margins due to high New Zealand dollar exchange
rates and the overall lowering of alluvial headgrades throughout the West Coast
and Otago/Southland regions. To counter these effects DML has continued to
improve on operational efficiency and performance monitoring to optimise the
mining practices used.
This paper detains the background to the Poutini Project, the geology, plant
and equipment used together with descriptions of the current mining methods
employed.