While the global demand for gold is expected to grow over the long term, the global mined supply is expected to peak in 2022 before steadily decreasing as ore grades decline and large mining projects reach the end of their lives. The price of gold is not expected to rise at the same rate as demand, so miners will be incentivised to find more efficient and cost-effective ways of extracting gold from this lower-grade ore.
At the same time, mining
companies are under increasing pressure to lower the environmental impact of
their operations, and this trend is set to continue for the foreseeable future.
With environmental regulations tightening worldwide and shareholders becoming
more environmentally conscious, gold miners will be obliged to lower their
greenhouse gas emissions and decrease their use of toxic chemicals such as
cyanide in order to continue to operate. This, along with the need for more
efficient operation, necessitates innovation in the industry.
One of the major developments taking place in
gold mining and in the mining industry generally is the shift to renewable
energy, with gold mining companies such as Polyus already using renewable
energy to power 90% of their gold production. Many gold miners are
investigating new technologies with the potential to facilitate this shift.
Numerous other new and established technologies, aimed at both increasing the
efficiency of gold mines and decreasing their environmental impact, are also
being trialled and used by gold mining companies around the world.
Rio2
Rio2 is involved in a trial of
gold processing technology which uses molecularly imprinted polymers, rather
than activated carbon, to recover gold from cyanide leach. In August, the miner
signed a contract with Sixth Wave Innovations which will enable the continued
testing of Sixth Wave’s patented IXOS purification polymer at Rio2’s Fenix Gold
Project in Chile. Sixth Wave began the testing in September 2020 at its
facility in Utah, and testing will now move to Rio2’s Lince Infrastructure
facilities near the Fenix site.
The IXOS polymer is reusable,
and previous tests indicate that it outperforms activated carbon on several
fronts, being faster, cleaner and more cost-effective. The next stage of
testing will involve 50 days of onsite testing of the IXOS polymer, with
parallel testing on activated carbon leaching columns. If the testing is
successful, the companies will proceed with the next stage of testing,
incorporating the new technology into a long-term pilot plant which will
operate alongside a planned carbon adsorption circuit. This will provide
specifications for full-scale implementation of the new technology.
Gold Fields
The South African mining company
Gold Fields has ordered three Metso Vertical Plate Pressure Filters, with all
the associated equipment for dry tailings processing, for its Salares Norte site
in Chile. Gold Fields ordered the pressure filters from the Finnish industrial
machinery company Metso Outotec, and they are set for commissioning in 2022.
Dry tailings processing involves
the dewatering of mine tailings to achieve less than 20% moisture content,
followed by reuse of the water and storage of the remaining “dry” material in
an unsaturated tailings deposit. This form of tailings management is both safer
and more water efficient than the traditional method.
Dry tailings processing is particularly
appropriate for use at the Salares Norte mine. The site is located 4500m above
sea level in the Andean Mountains, where water is scarce and water efficiency
is particularly important in mining operations.

Barrick
Barrick Gold Corporation has
joined the “Charge On” Innovation Challenge, a competition launched by BHP,
Vale and Rio Tinto in partnership with Austmine, Australia’s leading mining
equipment, technology and services industry association. The aim of the competition
is to develop new concepts and solutions for large-scale haul truck
electrification, and the challenge is to develop a solution that will safely
deliver electricity to large surface haul trucks without adding time to the
haul cycle. This is expected not only to provide a zero-carbon energy source
but to potentially unlock value, as electric motors have fewer moving parts
than standard equipment.
Over 350 companies from across
19 industries have registered their interest as vendors, with 80 companies
submitting formal expressions of interest. With the help of Austmine, the
patrons of the challenge will evaluate proposals over the next month to create
a short-list of vendors to submit formal proposals. Site trials of the chosen
solution are expected to start within the next few years.
Many companies are currently
looking for ways to reduce the greenhouse gas emissions associated with mining,
and the decarbonisation of mining fleets would reduce the emissions produced by
surface mining operations.
Evolution
To increase the efficiency of
its operations, Evolution Mining has deployed Aspen Technology’s Mtell plant
monitoring software at its Mungari Gold Operations in Western Australia. The
software utilises historical and real-time operational and maintenance data to
identify specific failure signatures. This allows it to predict impending asset
breakdowns and thus assists in preventing them.
Evolution plans to use the
software to help mitigate unplanned downtime and optimise operations.
Itronics
At the beginning of the year, US-based
cleantech materials growth company Itronics announced that it had developed a
process capable of recovering silver and gold, as well as base and ferrous
metals, nutrient materials, and industrial minerals, from “sub-ore grade” mine
tailings. The process, called Rock Kleen Tailings Processing Technology, also
neutralises residual cyanide from the leaching process.
The use of cyanide in the gold
recovery process is associated with both environmental damage and human safety
risks. As a result, it is controversial, and the use of cyanide in heap-leach
applications is now banned in several countries. There has therefore been a
long search for alternatives to the use of cyanide in gold mining. One solution
which has already been utilised by Barrick Gold Corporation, among others, is
the replacement of cyanide with a safer chemical reagent called thiosulphate.
Itronics’ new technology offers another solution which also unlocks value from
mine waste materials.

Technological Solutions
In future, gold mining companies
will be required to increase the efficiency and cost-effectiveness of their
operations to counter the declining grade of ore and associated rise in the
costs of production. At the same time, they will be obliged by increasing
pressure from governments, investors and communities to decrease their
environmental footprint. Many are therefore testing, using or contributing to
the creation of technologies capable of bringing them closer to these goals.
New technologies capable of simultaneously improving the environmental
footprint and the cost-effectiveness of mines are particularly promising. Many
have recently become available, and mining and other companies are taking steps
to develop more.