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I wonder if there are any chemical effects from heating the sand to 500 degrees Celsius. Finely roasted sand.

• isoprophlex 1y ago
  None, really. Pure, fine sand being mostly silicon dioxide, it melts at ~2000 and boils at ~3000 C, still without decomposing or reacting. It is really extremely chemically stable. That said in practice, at scale... before filling up your storage tank you'd probably need to pre-heat it once to remove all moisture and volatile gunk adsorbed onto the sand.
• LtdJorge 1y ago
  It's as inert as it gets
• grues-dinner 1y ago
  This is crushed soapstone, so it's mostly talc. Talc is apparently more or less stable up to about 800C, where it starts to break down into enstatite and silica: https://nvlpubs.nist.gov/nistpubs/jres/15/jresv15n5p551_A1b.pdf https://nvlpubs.nist.gov/nistpubs/jres/15/jresv15n5p551_A1b.... If it were pure silica sand, you could presumably get even hotter before anything changes chemically, but at the that point you start having materials issues with metal parts of the system: 500C is about the limit for ordinary steels to lose strength (and many are less than that - heat effects can often start at 300C).
  • isoprophlex 1y ago
    Interesting, thanks for pointing that out, I didnt catch that they're not using actual sand.