Mining And Refining: Lead, Silver, And Zinc

If you are in need of a lesson on just how much things have changed in the last 60 years, an anecdote from my childhood might suffice. My grandfather was a junk man, augmenting the income from his regular job by collecting scrap metal and selling it to metal recyclers. He knew the current scrap value of every common metal, and his garage and yard were stuffed with barrels of steel shavings, old brake drums and rotors, and miles of copper wire.

But his most valuable scrap was lead, specifically the weights used to balance car wheels, which he’d buy as waste from tire shops. The weights had spring steel clips that had to be removed before the scrap dealers would take them, which my grandfather did by melting them in a big cauldron over a propane burner in the garage. I clearly remember hanging out with him during his “melts,” fascinated by the flames and simmering pools of molten lead, completely unconcerned by the potential danger of the situation.

Fast forward a few too many decades and in an ironic twist I find myself living very close to the place where all that lead probably came from, a place that was also blissfully unconcerned by the toxic consequences of pulling this valuable industrial metal from tunnels burrowed deep into the Bitterroot Mountains. It didn’t help that the lead-bearing ores also happened to be especially rich in other metals including zinc and copper. But the real prize was silver, present in such abundance that the most productive silver mine in the world was once located in a place that is known as “Silver Valley” to this day. Together, these three metals made fortunes for North Idaho, with unfortunate side effects from the mining and refining processes used to win them from the mountains.

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More EL Chemistry: Luminescent Ink

[Jeri Ellsworth] continues her experiments with electroluminescence, this time she’s making EL ink. The ink she’s looking for is Zinc Sulfate in a solution. The process she chose is to re-dope some glow powder so that it can be excited by the field around an AC current. In her video (embedded after the break) she talks about the chemical properties she’s after by detailing a cubic lattice of zinc and sulfur atoms with an added copper atom (adding that atom is a process called doping).

The quick and dirty synopsis of the experiment starts by washing the glow powder with dish soap to acquire zinc sulfide crystals. Then she combined copper sulfate and zinc shavings from the inside of a modern penny to yield copper metal and zinc sulfate suspended in solution. That was mixed with the zinc sulfide from the glow powder washing and doped with a little more copper sulfate. The excess liquid is poured off, the test tube is capped with glass frit, and the whole thing hits the kiln to start the reaction. The result glows when excited by alternating current, but could have been improved by adding chlorine atoms into the mix.

We’re excited every time we see one of [Jeri’s] new chemistry hacks. We’d love to see more so if you’ve come across interesting chemistry experiments during your Internet travels, please let us know about them. Just make sure you have some idea of what you’re doing when working with chemicals… safety first.

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