18 October 2012 - New research has
assessed the environmental impact of gold production using life
cycle assessment and estimated embodied energy and greenhouse
gases, embodied water and solid waste burden that each tonne of
Gold is a highly valued metal, used not only in jewellery, but
also electronics and other industrial applications, dentistry
and for investment. Like other metal industries, there
is increased pressure for the gold industry to reduce its
The industry is developing more
sustainable solutions and technologies, but these need to be
informed by knowledge about the environmental impacts of the
different production stages, such as mining, extraction from
the ore, recovery and refining.
The study conducted a life-cycle assessment (LCA) to provide
estimates of the energy use, water use, waste production and
GHG emissions of gold production using data from numerous
sources, including published papers, reports and company
A number of processes were considered: open pit mining to
extract the ore, cyanide leaching to extract the gold from
ore, carbon adsorption to extract the gold from the cyanide
solution and electrolytic refining and chlorination to refine
The LCA assessed production from both non-refractory ores, which
are relatively easy to treat, and refractory ores where the
gold is 'locked-in' and requires more complex processing. As
non-refractory ores become depleted, the ability to recover gold
from refractory ores has become more important.
For an ore grade (i.e. metal content) of 3.5 gram per tonne of
ore, the study estimated that production of each tonne of gold
from non-refractory ore used approximately 200,000 gigajoules
(GJ) of energy and 260,000 tonnes of water.
It produced 18,000 tonnes of GHGs (CO2 equivalent) and
1,270,000 tonnes of waste solids. For refractory ores, the
GHG emissions and energy use were about 50% higher, owing to
additional processing steps required.
Per tonne of metal produced these figures were several orders of
magnitude greater than those for other metals, such as steel
However, gold is produced in much smaller quantities, so
the total environmental footprint for global gold production
is smaller than some other commonly used metals, including
steel, copper and aluminium.
The stages that contributed the most to gold's environmental
impact were mining and comminution (crushing and grinding of
the ore). Electricity use was responsible for just over half
of the GHG emissions.
This indicates that attempts to lessen the environmental
impact of gold production should focus on these two stages.
Mining and comminution are highly dependent on the grade of
gold ore, as the lower the grade, the greater the amount
that needs to be mined and the more crushing and grinding is
required to extract the gold from the ore.
As there is a general decline in gold ore grades it is likely
the need to address the environmental impacts of mining and
comminution will become even more important.
Some technological developments, such as microwave heating and
high pressure grinding rolls, could reduce the impact, but
this will depend on the characteristics of the ore.
Citation: Source: Norgate, T. & Haque, N.
(2012) Using life cycle assessment to evaluate
some environmental impacts of gold production. Journal
of Cleaner Production
29-30: 53-63. Doi:10.1016/j.jclepro.2012.01.042.
From:"Science for Environment Policy": European
Commission DG Environment News Alert Service, edited
by SCU, The University of the West of England,