5 ms·

I wonder why manufacturers don't just use filtered atmospheric air in the process to create low-background steel, if it is infact valuable.

saagarjha 6y ago
Not valuable enough to bother.
- nix23 6y ago
  So salvage it from sunken ships is cheaper then?
  - DonHopkins 6y ago
    Just cheaper for whoever salvages the ship -- somebody else had to pay for the sunken cost of building and sinking the ship.
    - rrrrrrrrrrrryan 6y ago
      > sunken cost Nice.
    - nix23 6y ago
      > somebody else had to pay for the sunken cost of building and sinking the ship Na remember it was war, so all the money went back to the economy :/
      - fennecfoxen 6y ago
        Money-oriented thinking is a road to economic misunderstanding. The economy is about stuff. In practice one often measures all the stuff using money, yes, because what else would one use? but as a proxy measure for its value; it's never actually about the money itself. (stuff = "final goods and services" to be technical)
        nix23 6y ago
        > because what else would one use? Energy witch can be food, oil, gas, the energy transformator is a human (or his brain) a maschine or a animal, and the exchange between energie to the endresult is often money. So money/exchangemedium has just the worth both partys agreed on.
        fennecfoxen 6y ago
        Now you are measuring electricity instead of the light you read by, and fuel instead of the vacation trip you take with it. You have worsened the problem I refer to.
        nix23 6y ago
        Energy IS electricity, and to create a Lightbulp you NEED energy, it's exactly the same. For your vacation trip you NEED energie in form of food an fuel, the vehicle you travel in, is made by food and fuel...exacly the same. If the transport company accept your fuel (or workforce witch again is fulled by energie (your food)) as payment, you exchanged energie to energie, probably they dont and thats why you use a exchangemedium called money. EDIT: You dont have to messure anything, if you need light exchange energy to light, travel exchange fuel to distance, working body food to (body)-energy. To make stuff you calculate the sum of the energie needed for, and thats the price of the product, sure exeptions like apple exists ;)
        fennecfoxen 6y ago
        the fundamentally inescapable problem is your approach measures an input instead of output, and thus makes technology improvements look like an economic crash consider the 'light' market: https://ourworldindata.org/uploads/2013/12/Trends-in-the-Prices-of-Energy-for-Lighting-and-of-Lighting-Services-1300-2000-Fouquet-and-Pearson-20120.png https://ourworldindata.org/uploads/2013/12/Trends-in-the-Pri...
        doukdouk 6y ago
        Surely energy input is the right metric. If I use a gallon of gas to power a life-saving ambulance or if I burn it just for fun, those two actions should have the same importance.
  - awalton 6y ago
    Yes. The demand for low background steel and lead is in the few dozen tons per year max, not millions of tons per year. Salvaging it is probably at least an order of magnitude cheaper than making new low background steel once you realize the amount of hassle involved. Furthermore, it's fairly easily recycled if you're not launching it into space (which is a common use case for the stuff, since building space probes to study the cosmic background is all the rage these days).
chrisbrandow 6y ago
Extremely difficult to separate different molecules that differ by only the weight of a single neutron.
- ars 6y ago
  They are using Oxygen, Oxygen can't become radioactive for longer than a few seconds anyway. All they need to do is filter for pure oxygen, nitrogen is fine as well. It's really just CO2 that's the problem.
  - catalogia 6y ago
    I'm not sure about this; smelting lead is generally done in a blast furnace, fed with coke. Burning that coke is going to produce a ton of CO2. Is that good enough because the carbon in the coke is all very old? (Searching for information relating to C-14 and coal lead me to a bunch of wacko new earth creationist websites claiming that carbon dating indicates coal is young...) Also, maybe this isn't really a concern, but "high temperature and pure oxygen" makes me think "metal fire."
  - awalton 6y ago
    So this is all kinds of wrong. When you make steel, you typically use 99+% pure oxygen - modern mills do air separation and reject nitrogen and argon (which makes steel brittle when it's dissolved in) and basically anything they can reasonably separate out but oxygen. But furthermore, it's not radioactive oxygen isotopes that get into the steel in the first place - they're scant to non-existent in nature, since all three common isotopes of oxygen are stable and most of the rest decay in seconds. It's other radioactive isotopes in the air from the bomb tests. 99+% isn't 100%, and it turns out those tiny fractions of a percent of junk contain the isotopes that are the real problem, namely Cobalt-60 created by the nuclear tests. Carbon-14 isn't nearly as big of a problem, since its decay mode is just beta and can be designed around, but the gamma decay from Cobalt-60 contamination is much harder to deal with. Furthermore, because of Cobalt's position on the periodic table and the desire to have a small amount of cobalt in steel anyways to give it better working properties, it's not something that's easily filtered out, even in processes that reform steel like vacuum remelting which exist to make mechanically harder and better quality steel by slow melting and recrystalization. Once the Cobalt's in there, it's in there - you just have to wait for it to decay. As it turns out, we're in luck, most of the fallout from those bomb tests has passed through numerous half-lives and is much less of a problem today than it was in the 1980s and 1990s when the low background stuff became such a hot commodity. So it doesn't really matter as much that we're running out. Furthermore, oxygen separation technologies and cryogenic liquid handling have improved, so we can do an even better job keeping contamination out. If someone wanted to set up a low background mill, they probably could do it today with commodity molecular sieves and centrifugation of the oxygen rejecting all but the light fraction...
garmaine 6y ago
How do you suggest filtering by isotope?
- TimSchumann 6y ago
  I mean, there are ways to do this. None of which are remotely cost effective.
- number6 6y ago
  Centrifuges
  - renewiltord 6y ago
    This stuff is useful, but it isn't that useful that you're going to sift and build an entire toolchain.
- ars 6y ago
  Just filter for oxygen. Radioactive oxygen doesn't last more than a few seconds. The issue is contamination with Carbon (CO2). Nitrogen also is not a problem.
- gruturo 6y ago
  As others said, simply separating the CO2 away would mostly get rid of the problem - all non-stable isotopes of Oxygen have a max half life of 122 seconds, but, for the record, isotopic separation is easy when there is a very large difference in atomic weight. In Uranium's case it's difficult because it's 235/238 = 1.28% (actually way worse - Uranium hexafluoride is used, which adds 114 units, bringing the ratio down to 0.86%) In Oxygen's case the ratio would be at least 6.6% (15 vs 16). Most importantly in Uranium you are interested in the tiny amount of U235, while in Oxygen you'd be interested in the huge bulk of O16, O17, O18, which are the stable isotopes. O16 alone is 99.762% of all Oxygen, and you can afford to lose half in your centrifuge if it spares you a few cycles, it's not exactly hard to come by.
  - awalton 6y ago
    Great. None of these do anything for the real problem: Cobalt-60.

saagarjha 6y ago

Not valuable enough to bother.

nix23 6y ago
So salvage it from sunken ships is cheaper then?
- DonHopkins 6y ago
  Just cheaper for whoever salvages the ship -- somebody else had to pay for the sunken cost of building and sinking the ship.
  - rrrrrrrrrrrryan 6y ago
    > sunken cost Nice.
  - nix23 6y ago
    > somebody else had to pay for the sunken cost of building and sinking the ship Na remember it was war, so all the money went back to the economy :/
    - fennecfoxen 6y ago
      Money-oriented thinking is a road to economic misunderstanding. The economy is about stuff. In practice one often measures all the stuff using money, yes, because what else would one use? but as a proxy measure for its value; it's never actually about the money itself. (stuff = "final goods and services" to be technical)
      - nix23 6y ago
        > because what else would one use? Energy witch can be food, oil, gas, the energy transformator is a human (or his brain) a maschine or a animal, and the exchange between energie to the endresult is often money. So money/exchangemedium has just the worth both partys agreed on.
        fennecfoxen 6y ago
        Now you are measuring electricity instead of the light you read by, and fuel instead of the vacation trip you take with it. You have worsened the problem I refer to.
        nix23 6y ago
        Energy IS electricity, and to create a Lightbulp you NEED energy, it's exactly the same. For your vacation trip you NEED energie in form of food an fuel, the vehicle you travel in, is made by food and fuel...exacly the same. If the transport company accept your fuel (or workforce witch again is fulled by energie (your food)) as payment, you exchanged energie to energie, probably they dont and thats why you use a exchangemedium called money. EDIT: You dont have to messure anything, if you need light exchange energy to light, travel exchange fuel to distance, working body food to (body)-energy. To make stuff you calculate the sum of the energie needed for, and thats the price of the product, sure exeptions like apple exists ;)
        fennecfoxen 6y ago
        the fundamentally inescapable problem is your approach measures an input instead of output, and thus makes technology improvements look like an economic crash consider the 'light' market: https://ourworldindata.org/uploads/2013/12/Trends-in-the-Prices-of-Energy-for-Lighting-and-of-Lighting-Services-1300-2000-Fouquet-and-Pearson-20120.png https://ourworldindata.org/uploads/2013/12/Trends-in-the-Pri...
        doukdouk 6y ago
        Surely energy input is the right metric. If I use a gallon of gas to power a life-saving ambulance or if I burn it just for fun, those two actions should have the same importance.
- awalton 6y ago
  Yes. The demand for low background steel and lead is in the few dozen tons per year max, not millions of tons per year. Salvaging it is probably at least an order of magnitude cheaper than making new low background steel once you realize the amount of hassle involved. Furthermore, it's fairly easily recycled if you're not launching it into space (which is a common use case for the stuff, since building space probes to study the cosmic background is all the rage these days).

chrisbrandow 6y ago

Extremely difficult to separate different molecules that differ by only the weight of a single neutron.

ars 6y ago
They are using Oxygen, Oxygen can't become radioactive for longer than a few seconds anyway. All they need to do is filter for pure oxygen, nitrogen is fine as well. It's really just CO2 that's the problem.
- catalogia 6y ago
  I'm not sure about this; smelting lead is generally done in a blast furnace, fed with coke. Burning that coke is going to produce a ton of CO2. Is that good enough because the carbon in the coke is all very old? (Searching for information relating to C-14 and coal lead me to a bunch of wacko new earth creationist websites claiming that carbon dating indicates coal is young...) Also, maybe this isn't really a concern, but "high temperature and pure oxygen" makes me think "metal fire."
- awalton 6y ago
  So this is all kinds of wrong. When you make steel, you typically use 99+% pure oxygen - modern mills do air separation and reject nitrogen and argon (which makes steel brittle when it's dissolved in) and basically anything they can reasonably separate out but oxygen. But furthermore, it's not radioactive oxygen isotopes that get into the steel in the first place - they're scant to non-existent in nature, since all three common isotopes of oxygen are stable and most of the rest decay in seconds. It's other radioactive isotopes in the air from the bomb tests. 99+% isn't 100%, and it turns out those tiny fractions of a percent of junk contain the isotopes that are the real problem, namely Cobalt-60 created by the nuclear tests. Carbon-14 isn't nearly as big of a problem, since its decay mode is just beta and can be designed around, but the gamma decay from Cobalt-60 contamination is much harder to deal with. Furthermore, because of Cobalt's position on the periodic table and the desire to have a small amount of cobalt in steel anyways to give it better working properties, it's not something that's easily filtered out, even in processes that reform steel like vacuum remelting which exist to make mechanically harder and better quality steel by slow melting and recrystalization. Once the Cobalt's in there, it's in there - you just have to wait for it to decay. As it turns out, we're in luck, most of the fallout from those bomb tests has passed through numerous half-lives and is much less of a problem today than it was in the 1980s and 1990s when the low background stuff became such a hot commodity. So it doesn't really matter as much that we're running out. Furthermore, oxygen separation technologies and cryogenic liquid handling have improved, so we can do an even better job keeping contamination out. If someone wanted to set up a low background mill, they probably could do it today with commodity molecular sieves and centrifugation of the oxygen rejecting all but the light fraction...

garmaine 6y ago

How do you suggest filtering by isotope?

TimSchumann 6y ago
I mean, there are ways to do this. None of which are remotely cost effective.
number6 6y ago
Centrifuges
- renewiltord 6y ago
  This stuff is useful, but it isn't that useful that you're going to sift and build an entire toolchain.
ars 6y ago
Just filter for oxygen. Radioactive oxygen doesn't last more than a few seconds. The issue is contamination with Carbon (CO2). Nitrogen also is not a problem.
gruturo 6y ago
As others said, simply separating the CO2 away would mostly get rid of the problem - all non-stable isotopes of Oxygen have a max half life of 122 seconds, but, for the record, isotopic separation is easy when there is a very large difference in atomic weight. In Uranium's case it's difficult because it's 235/238 = 1.28% (actually way worse - Uranium hexafluoride is used, which adds 114 units, bringing the ratio down to 0.86%) In Oxygen's case the ratio would be at least 6.6% (15 vs 16). Most importantly in Uranium you are interested in the tiny amount of U235, while in Oxygen you'd be interested in the huge bulk of O16, O17, O18, which are the stable isotopes. O16 alone is 99.762% of all Oxygen, and you can afford to lose half in your centrifuge if it spares you a few cycles, it's not exactly hard to come by.
- awalton 6y ago
  Great. None of these do anything for the real problem: Cobalt-60.