Molten Aluminum Temperature Measurement: Smelting & Foundries
Aluminum smelters take raw bauxite and convert the alumina found in bauxite into the metal we know as aluminum. This is a process that requires an enormous amount of electricity and smelters are often located close to hydro-electric power stations. Infrared pyrometers are used at many different stages of this process, but they are most important for molten aluminum temperature measurement after the metal has been smelted down and is being poured and cooled into different shapes – ingots, billets or pigs.
Molten Aluminum Stream
The smelting of aluminum occurs at 800°C/1475°F, while the melting point of aluminum is 660°C/1190°F. As a result, the molten aluminum contains excess thermal energy as it is drawn from the smelting pot. This excess energy is sometimes used to melt supplementary recycled aluminum before the metal is poured into the ingot molds. The addition of this supplemental aluminum cools the stream, therefore an accurate, real-time stream temperature is essential for optimal efficiency.
Williamson Wavelength Advantage
Hot metal temperature may be confirmed by measuring the stream temperature as it flows from one vessel to another, or while free falling from a trough. While an immersion thermocouple may be used for molten aluminum temperature measurement, an infrared thermometer is more effective and efficient when measuring in locations that are fast-flowing. In these locations, the use of thermocouples is often problematic due to the highly corrosive nature of aluminum.
- Eliminates problematic thermocouple replacement.
- Provides continuous real-time temperature measurement.
- The infrared thermometer must be installed to measure the molten metal stream at a point where it is free falling, a dross-free area just after a skimmer block, or in a fast-flowing trough where adequate mixing will occur.
The molten aluminum is poured into molds to form ingots, billets, or pigs. As the metal cools it solidifies. Once adequately cool, the metal may be removed from the mold as a solid chunk of metal. If the metal is removed from the mold before it has cooled sufficiently, then the metal may be too soft or still may be a liquid in the center, and a serious safety issue can result. In some cases, the metal is further cooled with an air / water combination. Because the aluminum may enter the cooling station over a wide range of temperatures, an infrared thermometer is used to adjust the amount of cooling necessary.
Williamson Wavelength Advantage
Because aluminum is a non-greybody material, a highly accurate temperature measurement is obtained only using a multi-wavelength sensor; however, a short-wavelength single-wavelength sensor will provide a reasonably accurate reading on a cast surface at a fraction of the cost.
- Assures that the metal is sufficiently cool to be safely removed from the mold.
- Optimizes cooling fans and water spray, conserving energy when appropriate.
Consult With One of Williamson’s Temperature Experts
We would love to discuss your temperature measurement application with you.