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Proposed magnesium complex raises serious questions

Having spent a fair amount of time roaming around New Mexico’s Florida Mountains while on the faculty in the Department of Earth and Planetary Sciences at the University of New Mexico, I was rather aghast in reading “Deming Targeted for Magnesium Complex” in the Journal’s June 22 Business Outlook.

When commenting on the article to former faculty colleagues over a few days after the article’s publication, I found that they, too, shared my perplexed response.

Thus, I ask in the context of the grand challenge of the human race to be better stewards of Earth is there wisdom in developing a magnesium extraction facility in Southwest New Mexico and processing “one billion tons” of dolomite?

Indeed, the Florida Mountains do expose a large volume of Paleozoic age dolomite-bearing rock, but so do very many mountain ranges in the western United States.

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First, some background. Dolomite is a member of the carbonate mineral “family” and has an approximate chemical formula (Ca,Mg)CO3, where the relative concentration of calcium and magnesium can vary because the cations are similar in size and have identical (+2) valence states. When in equal proportions, MgCO3 comprises 45.65 percent and CaCO3 comprises 54.35 percent. Not to add confusion here, but dolomite can make up a large percentage of a sedimentary carbonate rock, called dolomite (or dolostone by some to try to avoid confusion), which can form in many ways, including through biogenic processes.

To date, the most common ways we, globally, have produced magnesium involve its extraction from sea water or lake brines, not from dolomite.

That said, there is an abundant scientific literature on the dissolution of dolomite to eventually retrieve magnesium. Sparing the details, the process, to be efficient, involves an acidic solution at elevated temperatures.

Finally, let’s do some math. One billion tons of dolomite translates into 907.185 billion kilograms of dolomite, which, at a density of 2,840 kilograms per cubic meter translates into 0.3194 cubic kilometers of dolomite. That is a non-trivial volume.

I am glad that the permitting process for the “magnesium metal complex” has yet to begin. I hope that the following questions, among others, will be addressed in this process:

• How much water will be needed for magnesium extraction on an annual basis and where will it come from?

• How much energy will be involved in heating the acidic solution to a temperature that is efficient for magnesium extraction and where will it come from?

• What will be done with the used acidic solution?

• Will the “one billion tons” of dolomite be transported (trucked) some 30-plus kilometers to the magnesium processing facility and then processed?

• When carbonate minerals are dissolved in an acidic solution, carbon dioxide is released. Will the CO2 be sequestered, or simply released into the atmosphere?

• Can the Deming area support/sustain the “about 5,000 workers” who may eventually be involved in the facility?

I am certainly in favor of bringing well-paying, skilled jobs to New Mexico, but in these times in which we live, and perhaps future generations live, our decisions must be centered around scientific, as well as moral and ethical considerations.

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