January 2006 (PDF 2.9 MB) - Barrick Gold Corporation

Cowal Gold Project – Cyanide Management Plan
Table 1
Project Summary
Project Component Description
Mining and Waste Rock
Management
Processing Plant and
Tailings Management
Lake Isolation System
The mine will be developed by conventional open pit methods, mining both oxide
(weathered) ore which comprises the upper portion of the orebody and primary
(unweathered) ore which constitutes the majority of the orebody. The waste rock (rock
containing no commercial gold) and ore (rock containing commercially viable quantities of
gold) is broken through a routine sequence of in-pit drilling and blasting. Broken rock is
hauled from the pit to be placed within dedicated waste rock emplacements or, in the case
of ore, direct to the primary crusher or run-of-mine (ROM) stockpile.
Broken ore from the mine will either be stockpiled or hauled to a primary crusher located
near the processing plant. The crushed ore will then be conveyed to the grinding circuit
which will reduce the ore to a finely ground slurry. After being ground, primary ore will
pass to a flotation circuit where the gold-bearing portion of the slurry will be floated off as a
froth or concentrate. The concentrate will then pass to a leaching circuit where cyanide is
added to leach gold from the concentrate. The flotation circuit reduces the amount of ore
required to be cyanide leached and therefore greatly reduces cyanide usage. The ground
oxide ore will be cyanide leached without having to pass through the flotation circuit. The
gold extracted from the cyanide leaching circuit will be recovered and poured as gold bars
(or doré). These gold bars represent the final product of the mine and will be sold to a
refinery for purification.
The finely ground ore residue left after the flotation and leaching processes (tailings) will
be treated to destroy cyanide to prescribed limits and then pumped to one of two tailings
storages. The tailings storages are located about 3.5 km west of the Lake Cowal
shoreline (Figure 2). The tailings storages will be stage constructed throughout the mine
life by raising the height of the embankments in advance of storage requirements. The
bulk of the water from the tailings storages will drain from the surface of the tailings and
collect in the centre of each storage from where it will be reclaimed and recycled within the
processing plant.
The lake isolation system comprises a temporary isolation bund and a permanent lake
protection bund (Figure 2):
• The temporary isolation bund is designed to control water inflow to the pit
development area during construction of the permanent lake protection bund. The
bund is a short term feature and, once the permanent lake protection bund is
constructed and revegetated, it will be reshaped and rehabilitated.
• The lake protection bund will meet specific engineering criteria for compaction so
that it forms a permanent barrier between the lake and the open pit. Revegetation
will occur early in the mine life.
Water Supply Raw water requirements for the mine will be met through a combination of open pit
dewatering, recycling within the processing plant and the tailings water decant and return
system and (where the demand exceeds the available supply from these sources) makeup
water pumped from the external groundwater borefield (Figure 1). The borefield is
located within the Bland palaeochannel and is linked to the mine site via a buried pipeline.
The borefield comprises licensed groundwater production bores.
Access Road Upgrade and
Other Roadworks
Electricity Transmission
Line
Road access to the site will be via an upgraded route from West Wyalong. Within
ML 1535, haul roads and internal roads will be constructed as necessary to provide
transport links between the processing plant, tailings storages, waste rock emplacements
and open pit. In addition, the public road which ran in a north/south direction through
ML 1535 has been closed and replaced by a new public road which has been constructed
in a new travelling stock reserve adjoining the western boundary and part of the northern
and southern boundaries of ML 1535. The location of the new travelling stock reserve is
shown in Figure 2.
Electrical power supply to meet the demands of the Project will be supplied by a new
132 kV line constructed from Temora by Country Energy (Figure 1). A substation is being
constructed to distribute power within ML 1535.
Rehabilitation The rehabilitation philosophy for the mine site is to create stable rehabilitated landforms
which increase areas of endemic vegetation in ML 1535 and the status of lake-land
habitats.
HAL-02-07/1/25/CMP-01-Q.DOC 6 BARRICK