Open Pit Mining and the Need to go Deeper

Emerson’s Juan Carlos Bravo, a member of the metals and mining industry team, highlights the challenges in open pit mining and need to explore ever deeper.

Emerson's Juan Carlos BravoMore and more we hear how the trend on mining is to go underground. More recently, the Wall Street Journal article titled “Meet at the center of the Earth” highlights the $165 million investment that Rio Tinto is doing at Kennecott Utah Copper mine to explore the area, which may hold more than $5 billion worth of copper. At this mine, Rio Tinto has already dug an open-pit mine that is 2,000 feet deep and 2.5 miles wide and now has to go underground to reach new copper deposits. To accomplish this, they will need to dig underground mine shafts to a total depth of 4,000 feet—about twice as deep as most mines.

This make sense because mineral deposits are often concentrated in the same region, so when companies found ore bodies near the surface they removed ground and start mining. Once the surface deposits are depleted, they need to decide to go deeper or go somewhere else. In the past, going deeper was not possible due the cost and the limitations in the technology. Today is different, with new advancements in technology (like robotics) and high commodity prices going underground makes more sense, instead of transporting your entire infrastructure into a new location.

Rio Tinto is not alone. While attending EXPOMIN at Santiago last April, there was a half-day session to discuss underground mining in South America. In that session, CODELCO mentioned that 40% of their future projects will be underground, that includes Chuquicamata that is one of their largest open pit mines in Chile. CODELCO anticipates that with a continuous underground mining process it will reduce 20% of its operating cost and improve 50% its productivity.

But there are some challenges to do underground mining. First, it is more costly so commodities prices need to remain high in order to be feasible. Second, underground mining is more unsafe for humans and with robotics not implemented yet in all activities, you need to have a lot of prevision in order to have a safe working environment. Finally, underground mining has the potential of having more environmental impact. As you go deeper, you generate more waste material and have the potential to contaminate underground water sources. There needs to be good planning in order to avoid an environmental catastrophe.

I think that underground mining will be adopted in the future in spite of the risks. As we have discussed in previous blogs, the declining ore grades is one of the biggest problems for mining companies. Since most valuable deposits are located now at greater depths or in countries with more political instability, mine companies need to decide which of the two options will take. In my opinion, sometimes it’s easier, faster and cost effective to resolve logistic and technical issues to go underground rather than to try to wait for political problems to be resolved with no guarantee that they will emerge in the future. This makes underground mining more attractive.

Traveling to the center of the Earth still might be science fiction, but robotics and deep underground mining are becoming a reality.

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