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Gas Blasting

Short answer: Carbon dioxide blasting was conceived around 1924–25 by three southern Illinois coal men, a chemist, an electrical engineer and a mine operator. They wanted a non-explosive way to break coal that would be at least as safe as permissible explosives and produce less fine coal.

The Safety Mining Company took over the patents in 1927 under the trade name Cardox. A reusable high-strength steel tube is filled with liquid CO₂ at a charging plant and then placed in a drill hole. An electrically fired chemical heater turns the CO₂ supercritical almost instantly, and a rupture disc bursts at a set pressure, adjustable from about 1,200 to 2,800 bar. Mechanized mining made it rare in coal mines, but it's used again where explosives are restricted: in some coal mines, urban construction, frozen ground and concrete demolition.

VideoWrite-up4 sources

In collections:Engineering Oddities

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What should you know about Gas Blasting?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. CO₂ rock blasting was conceived around 1924–25 by coal men in southern Illinois and sold under the name Cardox.

    DD-070-F01 · Write-up · Exhibit A (Origins)

  2. A Cardox tube's rupture disc can be set to burst at pressures from about 1,200 to 2,800 bar.

    DD-070-F02 · Write-up · Exhibit D (The burst)

Video transcript: Gas Blasting: Breaking Rock With Liquid CO₂

DID YOU KNOW? Carbon dioxide rock blasting is a controlled rock breaking technique that uses rapidly expanding carbon dioxide instead of traditional explosives. In this method liquid CO₂ is injected into a sealed tube placed in a drilled hole in the rock. When triggered, the CO₂ instantly expands into gas, generating extremely high pressure that fractures the rock from the inside. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 21.2s Reel ·

Video coming soonGas Blasting · Instagram Reel
Gas Blasting: Breaking Rock With Liquid CO₂ Instagram Reel · · 21.2s

The write-up

Breaking rock with liquid CO₂. A heated steel tube of carbon dioxide bursts at up to 2,800 bar, a method that dates to the 1920s.

  1. Exhibit A

    Origins

    Around 1924–25, a chemist, an electrical engineer and a mine operator from southern Illinois conceived a non-explosive cartridge that used expanding CO₂ to break coal. In 1927 the Safety Mining Company took over the patents under the trade name Cardox.

  2. Exhibit B

    Regulated in Britain

    Britain regulated Cardox cartridges in coal mines under Explosives in Coal Mines (Cardox) Orders in 1932, consolidated in 1933.

  3. Exhibit C

    The tube

    A reusable high-strength steel tube is filled with liquid CO₂ at a charging plant, then placed in a drill hole. Inside is a chemical heater fired by a small electric charge.

  4. Exhibit D

    The burst

    The heater turns the CO₂ supercritical almost instantly. A rupture disc shears at a set pressure, adjustable from about 1,200 to 2,800 bar by disc thickness, and the gas escapes through angled ports.

  5. Exhibit E

    How fast

    The pressure rises over about 0.026–0.086 seconds, and the release lasts about 0.2 milliseconds.

  6. Exhibit F

    Then and now

    Mechanized mining made Cardox rare in coal mines. Concerns over mine safety and explosives control have brought it back for some coal mines, urban construction, frozen soil and concrete demolition. It's labor-intensive and less efficient for large-scale mining.

Questions people ask about Gas Blasting

Where was CO₂ blasting first conceived?

It was sold as Cardox from 1927.

Source: Write-up · Exhibit A (Origins) · The use of carbon dioxide for dislodging coal in mines (D. R. Schooler, Missouri School of Mines thesis)

What makes the liquid CO₂ burst out of the tube?

The disc shears at a set pressure.

Source: Write-up · Exhibit D (The burst) · Apparatus for blasting coal, U.S. Patent 2,207,191 (Cardox Corp.); Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

Up to about what pressure can the disc be set?

The range is about 1,200 to 2,800 bar.

Source: Write-up · Exhibit D (The burst) · Apparatus for blasting coal, U.S. Patent 2,207,191 (Cardox Corp.); Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

How long does the pressure release last?

The pressure rise beforehand takes about 0.03–0.09 seconds.

Source: Write-up · Exhibit E (How fast) · Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

Why did Cardox become rare in coal mines?

It's now used again where explosives are restricted.

Source: Write-up · Exhibit F (Then and now) · Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. Where was CO₂ blasting first conceived?

    1. Wales
    2. Southern Illinois
    3. Ruhr Valley
    4. Siberia
    Show the answer

    Answer: B. Southern Illinois It was sold as Cardox from 1927. Source: Write-up · Exhibit A (Origins) · The use of carbon dioxide for dislodging coal in mines (D. R. Schooler, Missouri School of Mines thesis)

  2. What makes the liquid CO₂ burst out of the tube?

    1. A fuse of dynamite
    2. A chemical heater and rupture disc
    3. A hydraulic ram
    4. A spark plug igniting the CO₂
    Show the answer

    Answer: B. A chemical heater and rupture disc The disc shears at a set pressure. Source: Write-up · Exhibit D (The burst) · Apparatus for blasting coal, U.S. Patent 2,207,191 (Cardox Corp.); Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

  3. Up to about what pressure can the disc be set?

    1. 28 bar
    2. 280 bar
    3. 2,800 bar
    4. 28,000 bar
    Show the answer

    Answer: C. 2,800 bar The range is about 1,200 to 2,800 bar. Source: Write-up · Exhibit D (The burst) · Apparatus for blasting coal, U.S. Patent 2,207,191 (Cardox Corp.); Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

  4. How long does the pressure release last?

    1. About 0.2 milliseconds
    2. About 2 seconds
    3. About 1 minute
    4. About 1 hour
    Show the answer

    Answer: A. About 0.2 milliseconds The pressure rise beforehand takes about 0.03–0.09 seconds. Source: Write-up · Exhibit E (How fast) · Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

  5. Why did Cardox become rare in coal mines?

    1. CO₂ was banned
    2. Mechanized mining
    3. It caused fires
    4. It was too cheap
    Show the answer

    Answer: B. Mechanized mining It's now used again where explosives are restricted. Source: Write-up · Exhibit F (Then and now) · Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)

Cite this case file

Easterling, Marcus. "Gas Blasting." The Detail Department (DetailEnjoyer), case file DD-070, last updated Jan 29, 2026. https://detailenjoyer.com/case/gas-blasting/

Permalink: https://detailenjoyer.com/case/gas-blasting/ · Last updated

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