Mines are not permanent operations, but rather have a life cycle
spanning from multiple decades to over a century. This life
cycle is divided into four main sequential stages:
-
The exploration stage when the deposit is discovered and
defined,
-
The development and construction stage where the mine site and
infrastructure are built,
-
The operational phase where the bulk of the ore is extracted,
and
-
The closure stage when the land is rehabilitated for other
uses after the ore has been extracted.
Various activities occur at each stage of the mine life cycle,
many of which are directly influenced by, or vulnerable to, the
local climate. Typical climate hazards that most Australian
mines are exposed to include floods, storms and extreme
rainfall, heatwaves, and bushfires.
Point and click on the image to see the detailed
explanation of the various activities and how they are
influenced by climate.
Machinery & Infrastructure
Background:
Processing plants, offices, water pumps, excavation and
haulage trucks are examples of typical machinery and
infrastructure found at most mines. Remote mines also build
miners camps for worker accommodation and may have to
construct railway lines to transport their commodity.
How is machinery & infrastructure impacted by climate and
climate hazards?
Mine sites are exposed to a range of climate hazards affecting
the infrastructure. Extreme heat can result in equipment
failures or buckling of railway tracks. Strong wind gusts or
cyclones can tear apart buildings. Bushfires and floods also
cause damage.
How are impacts managed and /or mitigated?
A lot of machinery is specifically built for harsh mining
environments. Infrastructure is also designed to be able to
handle certain climates. Some activities may occasionally have
to be paused to limit damage from hazards such as cyclones.
Conveyor belts moving coal from underground to the
processing plant.
Source:
Sustainable Minerals Institute, UQ
Worker Health & Safety
Background:
Mine sites employ a large number of people especially during
the mine site construction and operation stages. The majority
of workers are located on remote sites away from towns and
exposed to the natural elements on a daily basis.
How is worker health and safety impacted by climate and
climate hazards?
Workers may have to contend with a range of climate hazards
affecting their work environment, including extreme heat
aggravated by open and exposed outdoor environments. There are
also risks of bushfires, and floods that may cut off access to
or from a site.
How are impacts managed and /or mitigated?
All workers have to wear appropriate clothing to protect them
from the harsh conditions they are exposed to. Risk
assessments and short daily pre-work meetings are common ways
of identifying and managing risks from climate hazards. It may
be necessary to stop some kinds of work in extreme conditions.
Workers investigating composition of waste rock material.
Source:
Sustainable Minerals Institute, UQ
Water Quality
Background:
Mining produces waste rocks and tailings. These mine wastes
can contain salts and metals that are potentially harmful to
people and the environment. Water passing through mine wastes
may leach and become loaded with these substances,
contaminating soil, surface water and groundwater.
How is water quality impacted by climate and climate
hazards? .
The amount of salts and metals that can be leached from mine
wastes into the environment depends on weathering processes
that are controlled by various factors, including air
temperature, evaporation and infiltration of rainfall into the
waste. Long periods of dry weather allow salts and metals to
build-up, while heavy rainfall can allow them to be rapidly
released into the environment in large quantities.
How are impacts managed and /or mitigated?
Modern mine waste dumps and tailings storage facilities are
designed to minimise weathering and leaching of salts and
metals. This can be achieved by separating the wastes from
water flows, or with various technologies used to stabilise
the waste. Another option is treating and/or safely disposing
of contaminated water.
Build-up of turquoise, copper-rich water at the historical
copper mine in Kapunda, South Australia.
Source:
Sustainable Minerals Institute, UQ
Site Water Balance
Background:
Mines need water for their operations, for example to help
extract metals from rock or to spray roads for dust reduction.
To ensure a continual supply of water in dry periods, a lot of
water needs to be stored on the mine site. However, heavy
rainfall can lead to too much water, which can flood the
mining areas and access roads, and can require water to be
released to neighbouring rivers.
How is the site water balance impacted by climate and
climate hazards?
The site water balance measures the amount of water stored on
the site. It depends on the local climate and is most strongly
influenced by the amount of rain and evaporation. Climate also
influences local streams and groundwater, which may add water
to the site water balance.
How are impacts managed and /or mitigated?
Water is stored on sites using constructed basins or old mine
voids. Water is prevented from entering the mine site with
stream diversions or pumping of groundwater. Excess water of
reasonable quality may be released into rivers surrounding the
mine site.
Bowen Basin coal mine void converted into a site water
storage facility
Source:
Sustainable Minerals Institute, UQ
Flood Risk
Background:
Extreme rainfall can result in flooding of mine site
infrastructure such as roads, tailings storage facilities and
mine voids, as occurred in Queensland during the
devastating 2011 floods . Large floods can damage infrastructure, disrupt operations,
or even cause deaths and environmental disasters.
How is flood risk impacted by climate and climate hazards?
The size of a flood is related to the intensity and duration
of extreme rainfall events. Smaller rainfall events can also
cause floods if the soil is already saturated and is unable to
absorb more water. Flooding at mine sites near the coast can
be worsened by other factors such as tides and storm surges.
How are impacts managed and /or mitigated?
Mining infrastructure such as roads and dams are all designed
to Australian engineering standards. Engineering standards
provide design rules to prevent overtopping of structures and
catastrophic failures. Mine sites also control flood waters
with “bunds” that serve a similar purpose to river
bank levees in towns.
Flooding of regional access roads on the way to a mine site.
Flooding of regional access roads on the way to a mine site.
Source:
Adobe Stock Images
Site Revegetation
Background:
Clearing of vegetation to make way for a mine site is common
practice. Towards the end of the mine life cycle,
mine-impacted land needs to be rehabilitated. Revegetation is
one of the key rehabilitation activities that allows the mine
site to be repurposed for another use, such as grazing or
returning it to a native ecosystem.
How is site revegetation impacted by climate and climate
hazards?
Site climate is one of the important factors influencing
selection of plant species used in mine site revegetation.
Depending on the species, different aspects of climate can be
important. These include average rainfall and potential
evapotranspiration, whether the region experiences frosts, and
frequency and severity of droughts.
How are impacts managed and /or mitigated?
Mine sites are degraded landscapes that need our assistance to
be converted into new, man-made ecosystems. Ideally, the new
ecosystems are provided additional help and protection (from
wildlife and natural elements) in the initial years after
replanting to help them thrive under altered conditions. The
chances of the site being successfully revegetated are
improved by selecting native plants suited to the local
climate and the nutrient-deficient soils. Some mines run
revegetation trials to help guide this.
Native vegetation reestablishment on a constructed landform.
Source:
Sustainable Minerals Institute, UQ
As can be seen in the interactive figure above, climate plays an
important role on Australian mine sites, influencing the design
of infrastructure, how the site is managed, and worker health
and safety. Climate change means that climate conditions will
change into the future. As such, climate change impacts need to
be considered in the design, management and closure of mine
sites, to reduce the chance of negative consequences.