# Gas Blasting (DD-070)

> 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.

- Department: Tech (also Science)
- First published: 2026-01-29
- Last updated: 2026-01-29
- Permalink: https://detailenjoyer.com/case/gas-blasting/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## On the timeline

- **1924**: Three southern Illinois coal men conceive a CO₂ blasting cartridge (1924 or 1925)
- **1927**: The Safety Mining Company takes over the patents under the trade name Cardox
- **1932**: Britain issues Explosives in Coal Mines (Cardox) Orders
- **1933**: The British Cardox Orders are consolidated

Full timeline: https://detailenjoyer.com/timeline/?case=gas-blasting

## Quick facts

- **DD-070-F01**: CO₂ rock blasting was conceived around 1924–25 by coal men in southern Illinois and sold under the name Cardox. _(Write-up · Exhibit A (Origins))_
- **DD-070-F02**: A Cardox tube's rupture disc can be set to burst at pressures from about 1,200 to 2,800 bar. _(Write-up · Exhibit D (The burst))_

## 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. **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. **Regulated in Britain**: Britain regulated Cardox cartridges in coal mines under Explosives in Coal Mines (Cardox) Orders in 1932, consolidated in 1933.
3. **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. **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. **How fast**: The pressure rises over about 0.026–0.086 seconds, and the release lasts about 0.2 milliseconds.
6. **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.

## Related case files

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- [Cannikin Quake (DD-026)](https://detailenjoyer.com/case/cannikin-quake/): A far larger underground blast: the largest underground nuclear test the U.S. has conducted.
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## Reel vs. record

- **Nuance**: the liquid CO₂ isn't injected in the hole. A reusable steel tube is filled at a charging plant beforehand and then placed in the drill hole. [Cardox patent; Energies 2019]
- **Note**: Missing context on 'when triggered': an electrically fired chemical heater inside the tube turns the CO₂ supercritical, and a rupture disc bursts at a set pressure of about 1,200–2,800 bar. [Cardox patent; Energies 2019]
- **Note**: Nuance on 'instantly': the pressure builds over about 0.03–0.09 seconds before the disc bursts, and the release then takes about 0.2 milliseconds. [Energies 2019]
- **Missing context**: it isn't new. It was conceived around 1924–25 in southern Illinois coal mines and sold as Cardox from 1927. Britain regulated it under Explosives in Coal Mines (Cardox) Orders in 1932–33. [Schooler thesis; London Gazette]
- **Note**: Context on 'instead of explosives': it causes less vibration and pollution, but it's labor-intensive and less efficient, so it isn't suited to large-scale mining. Today it's used where explosives are restricted. [Energies 2019]

## Video: Gas Blasting: Breaking Rock With Liquid CO₂

- Duration: 21.2 s · Published: 2026-01-29
- File: https://detailenjoyer.com/assets/videos/DUHks-rESro.mp4

### Transcript

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!

## Questions & answers

**Q: Where was CO₂ blasting first conceived?**  
A: 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))_

**Q: What makes the liquid CO₂ burst out of the tube?**  
A: 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))_

**Q: Up to about what pressure can the disc be set?**  
A: 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))_

**Q: How long does the pressure release last?**  
A: 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))_

**Q: Why did Cardox become rare in coal mines?**  
A: 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))_

## Sources

- [The use of carbon dioxide for dislodging coal in mines (D. R. Schooler, Missouri School of Mines thesis)](https://scholarsmine.mst.edu/professional_theses/224/)
- [Apparatus for blasting coal, U.S. Patent 2,207,191 (Cardox Corp.)](https://www.freepatentsonline.com/2207191.html)
- [Positive phase pressure function and pressure attenuation characteristic of a liquid carbon dioxide blasting system (Energies, 2019)](https://doi.org/10.3390/en12214134)
- [Explosives in Coal Mines (Cardox) Order, 1933 notice (The London Gazette, May 26, 1933)](https://www.thegazette.co.uk/London/issue/33943/page/3547/data.pdf)

## 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/