Xstrata Copper North Queensland.pdf - Mount Isa Mines

Environmental performance
centre of the waste rock landform. This rock
is then covered with benign, competent
waste rock on the outside surface of the
waste rock landform. These landforms are
also designed to shed surface water and
thereby minimise any potential percolation
of rainfall into the core of the dumps. When
any area of the waste rock dump reaches
its full design height, or areal extent, these
areas are progressively rehabilitated with
vegetation native to the region. All of these
control measures combined greatly reduce
any potential for acid mine drainage.
EHM continues to stockpile benign,
competent waste rock to ensure sufficient
material is available to complete construction
of the waste rock landform and tailings dam
to the required specifications.
EHM continued to manage tailings produced
from our concentrator according to regulatory
requirements. The tailings storage facility is
audited annually by independent Registered
Professional Engineer Queensland (RPFQ)
Land disturbed (ha) – EHM
Major waste streams and disposal/treatment methods – EHM
Waste type Amount Treatment method
Recycled/reused
General/domestic
waste* (paper)
(t) 1 Recycled
Scrap metal (t) 1,245 Recycled off site by a scrap metal contractor
Waste oil (kL) 534 Collected and treated off site by licensed
contractors
Waste sent to landfill
General waste –
to landfill on site*
General waste –
to landfill off site*
Mining wastes
Excavated materials,
overburden and waste
rock
certified engineers to certify its environmental
performance complies with all relevant
regulatory requirements.
Two PhD studies being managed by the
University of Queensland in cooperation with
EHM continued in 2010. These studies are
investigating the potential ‘Environmental
Risks of Tailings Seepage in Naturally
Mineralised Areas’ and ‘An examination of
Options for Tailings Revegetation’, and we
will support these studies through to 2013.
General waste
General waste from EHM and our residential
village is contained and disposed of on site
in accordance with Environmental Authority
conditions. Waste aluminium cans from the
EHM village are donated to the local Lions
Club for recycling. Other materials such as
metal tin cans, cardboard and waste cooking
oil are recycled. Scrap steel is collected, taken
off site and recycled. Around 1,245 tonnes of
scrap metal was recycled in 2010.
(t) 1,381 Disposal in a non-hazardous landfill on site
(t) 35 Disposal in a non-hazardous landfill off site
(t) 16,782,266 Stored as per Plan of Operations
2009 2010
Rehabilitation during the year 28 25
Total rehabilitation completed to date 160 185
Area disturbed during the year 28
Total area disturbed 1,637 1,665
Processing wastes
Tailings (t) 9,180,989 Stored in a licensed facility as per Plan of
Operations
Regulated waste
Regulated wastes are removed from site
by licensed contractors and transported to
Townsville for recycling or disposal. Scrap
tyres are disposed of within designated cells
in the waste rock dumps.
Rehabilitation
Around 1,665 hectares (ha) of land has been
disturbed by our operation. During the life of
the mine, disturbed areas are progressively
rehabilitated to match the surrounding
landscape. In 2010, EHM rehabilitated a
further 25 ha, bringing total land rehabilitated
to date to 185 ha.
During 2010, the tailings capping trials
continued, involving three trial plots 30
metres by 30 metres in surface area, two of
which are store and release capping designs.
The objective of these trials is to determine
the most effective cover design to minimise
any potential post-closure environmental
risks. During the year, we commenced a
Tailings Revegetation trial to ascertain suitable
tailings remediation. The objective of the
field trials is to assess the physical constraints,
water storage and salt stratification within
the tailings profile with the use of different
amending materials. This information can
then be used for long-term modelling of
tailings revegetation.
In 2011, EHM will continue to rehabilitate
disturbed land on the waste rock landforms
as it becomes available.
Materials
A wide range of raw materials and other
consumables are used at EHM. The table
below shows the main materials consumed
at our operations by weight or volume in
2010. There was a significant increase in
cement use due to the advancement of the
underground decline and construction of the
magnetite plant and shaft sink. There was
also an increase in diesel and electricity use
as a result of more material movement and
mill throughput.
Transporting product,
goods and materials
In 2010, there were no environmental
incidents associated with the transportation
of concentrate between EHM and the Mount
Isa copper smelter.
* From 2010, general waste will be broken down into general waste disposed to landfill on site, off site,
and recycled. This figure was previously combined.
Sustainability Report 2010 101