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Does the Argument Against Open-Pit Mining Hold Water?

By Armando Alatorre Campos - College of Mining Engineers, Metallurgists and Geologists of Mexico - CIMMGM


By Armando Ernesto Alatorre Campos | Presidente - Mon, 01/30/2023 - 09:00

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Unfortunately, there is widespread opposition to -open-pit mining and it is r not just restricted to Mexico; many organizations around the globe have been insisting that the only environmental solution is to close, for good, this type of mining. However, can it really be done and can humanity afford it? Let’s explain, through a few examples, what economic consequences could arise if open pits disappear, like magic, from this planet. For that, some knowledge about how and where minerals occur is needed.

The very first case and the easiest to talk about is aluminum (Al), a metal that is deeply embedded in our modern world in uses that range from airplanes to cars to smartphones, cans and even in everyday home cooking, just to mention the main ones. Bauxite is the name of the rock that through open-pit mining and a complicated-expensive chemical treatment allow us to produce that extremely light, useful and durable metal. This kind of rock is formed, by means of long-term geological processes, directly on the Earth’s surface; normally, the economic deposits are no more than 30-40m thick. Therefore, it is completely impossible to have underground bauxite mines, given  such small dimensions. From an environmental perspective, for bad or good, aluminum, once obtained and used, can be recycled endlessly without losing quality, as happens with glass. On such grounds, someone could say that there is already enough metal extracted and that no new production is needed. If the number of humans remained constant, that could  probably be true, to some extent, but that is a highly improbable scenario. Very recently, the planet’s population reached 8 billion people. So far, there is not a visible, technical substitute for this metal within the next few decades. Are the coming generations condemned to live with decreasing amounts of aluminum that will only be available with an obvious increase in price?

Another example, copper, is obtained mainly from huge porphyry-Cu deposits around the Circum Pacific (Ring of Fire) area where, probably, 75 percent comes from open-pit mines. Fifteen out of the world’s 20 main Cu-producing mines in 2021   were surface operations. Besides Cu, these operations are the source of about 50 percent of the molybdenum used by humans. Can copper be obtained from underground mines? Definitely yes. The process and technology are well known from long ago. However, the costs are much higher and, because of that, restricted to a few deposits. p Sporadically, like in Chuquicamata (Chile), production might be transformed from surface to underground. Modern living and the new energy alternatives require an increasing amount of copper. The better-known use of this metal is in the form of electrical wires running within all the constructions used by humans. It is also in high demand for eolian and solar energy generation units. It can be an alloy with nearly 20 other metals to improve strength, corrosion and wear resistance as well as having machinability properties. This metal also can be recycled to some degree; however, again, the increase in the number of humans and new energy technologies do not leave room to produce smaller amounts.

The list of examples where open-pit mines supply materials can be endless: all ceramic products (tableware, sanitary ware, industrial, electrical) require clays (kaolin and ball clay, mainly), silica sand and feldspars; paper consumes kaolin for printability and ease of writing; glass needs silica sand, limestone and feldspar, some specialty glasses also need boron or lithium; cement uses limestone, gypsum and aggregates; steel is made of iron and coal (both mainly from open pits) as well as dolomite; phosphate fertilizers from phosphate mines; plastics make use of ground calcium carbonate (GCC) or wollastonite for wear resistance; diatomite is of great help as a filter in liquids that humans consume, such as wine, beer or several oils for cooking, such as olive oil, just to mention a few.

Some cases have no other technical alternative to open-pit mines and, in some others, going underground, although feasible, could mean lesser amounts of material available and a huge increase in production costs that will, certainly, be transferred to consumers. Then, the very first question could be: Is humanity willing to pay for much more expensive products of all sorts? Evidently, on environmental grounds, anyone can argue that, by and large, the costs to humanity will be even greater. Here is where balance and coexistence must perform together. As time goes by, more and more humans will live on the Earth’s surface so more mine-derived materials will be needed. Prohibition has shown in the past that it is not the better answer. Therefore, instead of thinking about closing down an economic activity, society urgently needs to work together to attain the best and most balanced scenario possible.

The Mexican government has also signaled its stance against open-pit operations; there is even a proposal to change (again) the Mining Law in this respect. There is also talk that the Ministry of Environment will no longer  authorize new open pits. However, have they realized that their much-dreamed-about lithium project will not be feasible at all without a new  open pit?

Photo by:   Armando Alatorre Campos

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