Seeing in Stereo: Satellite Mapping, Mining Volumetrics, and Gold

Penasquito satellite photo

Peñasquito gold mine is Mexico’s largest gold producer. Two pits, Peñasco and Chile Colorado, produce gold, silver, lead and zinc, to the tune of 567,800 ounces of gold in 2014. The mine sees its future in a copper-gold ore located in tactites beneath the current workings.

Peñasquito’s owners boast proudly on their website that the mine ‘achieved commercial production in 2010, on schedule and on budget.’ That’s no small feat in an industry dogged by unexpected setbacks, and in turn it’s no small measure thanks to fast, accurate and effective mapping and volumetric measurements.

Back in early 2010, Photosat stepped in to calculate mining volumetrics at the Peñasquito mine site.

The goal was to estimate the volume of rock and overburden mined at the site. We used our own high accuracy geophysical processing technology to make volume estimations directly from stereo satellite images that could show detailed 3-dimensional changes.

We started by taking two sets of stereo satellite images, a month apart: one in January and the next at the end of February.

Then we ran these stereo Worldview-2 satellite photos through our own proprietary geophysical elevation processing system.

The beauty of this approach was that we could work directly from the automatically derived elevations to estimate mining volumetric changes in the leach pad, the waste dumps, the ore stockpiles and even the pit itself. All calculations can be done with instantaneous sets of satellite photos – a snapshot of the entire mine site.

Penasquito mine volume decreases

Using the changes in the month-long gap we could determine the volume decrease from January to February, giving highly accurate calculations of the amount of rock and overburden removed from the mine pit.

We based our volume calculations on a 125% expansion factor for blasted rock, and came up with an estimate for the total removed from the pit in a month of 6,928,100 m3 of blasted rock, or 5,542,400 m3 of unblasted rock. This is necessarily a slightly inaccurate figure, but as mining operations go on fine-tuning becomes possible; knowing the proportion of the total removed made up of overburden with a lower expansion factor would tighten up the figures, for instance.


Penasquito mine volume increases

Meanwhile, waste dumps, ore stockpiles and leach pads grew by an estimated 6,091,000 m3 during the same period.


Leach pad satellite images

This final image shows a detailed view of the volumetric calculations over the leach pad, with an addition of 505,400 m3 over the month.

Find out more about PhotoSat’s mining volume calculations.

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