Argon is a colorless, odorless, and tasteless chemical element. As a noble gas, it is known for its inert nature, making it unreactive with other substances. This property makes argon valuable across many industrial applications.
Where Argon is Found
Argon is naturally abundant in Earth’s atmosphere, constituting approximately 0.93% of dry air by volume. It is the third most prevalent gas after nitrogen and oxygen. While trace amounts exist in volcanic gases, the atmosphere’s sheer volume makes air the most practical raw material for industrial argon production.
Extracting Argon from Air
Industrial argon production relies on cryogenic air separation, or fractional distillation of liquid air. This method leverages the differing boiling points of air’s constituent gases for separation. It is the most common and efficient technology for producing high-purity argon, nitrogen, and oxygen. The process involves cooling air to extremely low temperatures until it liquefies, then warming it to allow each component to boil off at its specific temperature.
The Steps of Cryogenic Distillation
The cryogenic distillation process begins by drawing atmospheric air and compressing it to high pressures. This compressed air is pre-treated to remove impurities like water vapor, carbon dioxide, and hydrocarbons. These contaminants could freeze at cryogenic temperatures and obstruct equipment. The purified air is then cooled to cryogenic temperatures, typically around -180°C, liquefying it via heat exchangers and refrigeration cycles.
Once liquefied, the air mixture enters a distillation column system, separating components based on their distinct boiling points. Nitrogen has the lowest boiling point at approximately -196°C, followed by argon at about -185.8°C, and oxygen at around -183°C. As the liquid air warms, nitrogen vaporizes first and is collected from the top of the column, while oxygen largely remains in liquid form at the bottom.
Argon, with a boiling point between nitrogen and oxygen, concentrates in a specific distillation column section, often called the “argon belly.” A side stream, typically 7-15% argon and mostly oxygen, is withdrawn. This crude argon stream then goes to a separate column, separating argon from remaining oxygen and trace nitrogen. Subsequent purification steps, including catalytic converters and additional distillation, achieve purity levels often reaching 99.99% or higher.
Why Argon is Produced
Argon’s inert and non-reactive properties make it valuable across many industrial sectors. In welding, it is used as a shielding gas in processes like TIG and MIG welding, protecting molten metals from atmospheric contaminants and oxidation for strong, clean welds. It also fills incandescent and fluorescent light bulbs to prevent filament oxidation, extending bulb lifespan.
Argon is employed in manufacturing double-pane windows, sealed between glass panes to enhance insulation and thermal efficiency. In the semiconductor industry, it creates a protective atmosphere during microchip fabrication, safeguarding sensitive materials from reactive gases. It also serves as a carrier gas in analytical chemistry, is used in fire suppression systems, food packaging to displace oxygen, and for preserving reactive substances or historical artifacts.