…If helium is lighter than air, how is it collected and put into tanks?
p.
Not sure.
[hijack]I find nitrous more interesting, anyway.[/hijack]
Carry on.
…What about nitrous is more interesting?
p.
Turns out they mine it from the ground!
In general, natural gas deposits have some helium component.
As an aside, I once wrote Cecil about this very question, either before this board existed or before I knew about it (8-10 yrs ago, I guess before the board was around). After perhaps 6 months, I got a form letter saying “Due to all the mail, Cecil cannot answer all questions…”
Nitrous oxide is a psychedelic drug, that’s what. (And in about half of the US, it’s legal to inhale recreationally.) More info here.
Man…the places I’ve been and the things I’ve seen on that stuff!
Here’s a Swedish cite:
http://kryolab.fysik.lu.se/dokument/e_helium.html
Apparently, helium makes up 23% of the known, visible universe.
You could obtain helium by fractional distillation of liquid air, which is how neon and argon are obtained, for instance[sup]1[/sup]. However, it is much more cost effective to obtain it from natural gas wells, as noted, where it occurs in much higher concentration. The atmosphere contains about 5200 parts per billion helium, which is in the process of escaping to space fairly rapidly:
http://www.c-f-c.com/charts/atmosph.htm
It occurs in higher concentration than krypton, for instance, which is also obtained for commercial use from the atmosphere.
The ultimate source of most free helium on the Earth is as a decay product of radioactive substances, so it gets replenished, as well as tending to accumulate in natural gas deposits.
[sup]1[/sup] - In industrial processing, neon is extracted as the most volatile component. The boiling point of helium is lower than that of neon, and they don’t cool the air down far enough to capture the helium and hydrogen, since it’s cheaper to obtain these gases by other processes:
Actually, the last link I intended to provide was this one:
[Dreaded IRRS (I Remember Reading Somewhere) Post coming]
The helium in the earth’s crust has its origin in alpha radiation from radioactive elements in the crust. Since each alpha particle comprises two protons and two neutrons, it’s actually a He nucleus, which later finds electrons somewhere to become a full-fledged He atom.
[/IRRS]
The slowly-decaying isotopes of thorium and uranium are way more common than you might think.