If an aluminium melting furnace can be compared to a heart, constantly circulating molten metal through its system, then the flux injection lance serves as its lungs — silently working to “cleanse” and purify the molten aluminium.
At first glance, a flux injection lance might appear to be a simple metal pipe. However, its role is far more critical — ensuring the aluminium that leaves the furnace is clean, refined, and free of unwanted gases or impurities that can compromise the quality of the final product. So, how does this seemingly modest tool achieve such an important function? Let’s explore below.
Flux Injection Lance: Operation and Role in Aluminum Melting Furnaces
Source: Daiwa Lance International
What Is a Flux Injection Lance?
As the “lungs” of the refining process, the flux injection lance plays a vital role in purifying molten aluminium to produce a high-quality output. Its primary function is to inject a special refining agent — flux — into the molten metal.
This flux helps eliminate impurities such as oxides and hydrogen and separates slag from aluminium, similar to how lungs filter out toxins from the air we breathe.
Structure of a Flux Injection Lance
1. Long Lance
The main body of a flux injection lance is typically constructed from mild steel pipe. However, due to the extreme operating temperatures inside aluminium melting furnaces, the pipe’s durability must be enhanced.
To achieve this, the lance is often reinforced with a heat-resistant coating — most effectively, an aluminium diffusion layer (calorized coating) applied both internally and externally.
This layer acts as a thermal barrier, increasing the lance’s lifespan by 3 to 7 times and protecting it from cracking or deformation at temperatures exceeding 700°C. As a result, the lance maintains consistent performance and durability even under continuous high-heat operations.
2. Gas Connection
Another key element of the flux injection lance is its gas connection system. One end of the lance is connected to an inert gas supply, typically argon or nitrogen. These gases help transport the flux into the molten aluminium and remove unwanted gases and oxides — all without triggering adverse chemical reactions.
This combination of inert gas and flux works together to cleanse the molten metal efficiently and safely.
Benefits of Using a Flux Injection Lance in Aluminium Melting Furnaces
The flux injection lance serves as a bridge between the chemical refining process and safe, efficient furnace operation. Below are the primary advantages it offers:
1. Boosting Chemical Reaction Efficiency
Flux acts like a refining agent, composed of inorganic salts such as sodium chloride (NaCl) and calcium fluoride (CaF₂). When properly injected into the molten aluminium, it reacts with impurities, forming slag that floats to the surface for easy removal.
A high-quality flux injection lance ensures precise delivery of flux deep into the molten metal, where it can react most effectively. This targeted action enhances impurity removal, reduces slag formation time, and results in cleaner, purer aluminium.
Additionally, a heat-resistant lance—reinforced with ceramic or calorized coatings—reduces the frequency of replacements, minimizing furnace downtime and manual intervention.
2. Protecting Worker Health
By injecting flux directly into the molten aluminium rather than spreading it manually or externally, the lance significantly reduces worker exposure to harmful fumes, dust, and vapours.
This not only creates a safer work environment but also helps in maintaining better air quality around the furnace area, reducing long-term health risks for operators.
3. Reducing Flux Consumption
Compared to a rotary degasser, which often requires higher gas volumes and may lead to uneven flux distribution, the flux injection lance provides precise, direct delivery to the molten bath.
This results in improved flux efficiency — less flux is needed to achieve the same refining effect. The outcome is reduced material costs and improved operational economy without compromising performance.
Choosing the Right Size of Flux Injection Lance
Selecting the appropriate size of a flux injection lance is essential to achieving optimum performance. The choice largely depends on furnace capacity, operating conditions, and refining goals.
For small to medium furnaces, flux injection lances offer a cost-effective, flexible, and easy-to-control solution. In contrast, for large-scale, continuous operations requiring maximum degassing efficiency, rotary degassers may be a better fit.
Available Sizes and Specifications
To meet diverse operational needs, flux injection lances are available in eight standardized sizes, each designed for performance, durability, and ease of use.
Key specifications include:
Outside Diameter: From 1/4” to 2” — covering compact to large-scale applications
Wall Thickness: 2.0 mm to 4.0 mm — ensuring the ideal balance between durability and thermal response
Length Options: 2.0 m to 6.0 m — customizable to match furnace depth and operator safety requirements
Why proper sizing matters:
- Prevents flux wastage and ensures uniform distribution
- Allows complete coverage of the furnace bottom
- Enhances operator safety through optimal lance length
Conclusion:
The flux injection lance may appear simple, but its contribution to the efficiency, safety, and quality of aluminium refining is enormous. Acting as the silent “lungs” of the furnace, it ensures every batch of molten aluminium breathes cleaner — leading to stronger, purer, and more reliable metal output.
For more information, please contact our sales team at sales@daiwaanayasteel.com.
Daiwa Anaya Steel Private Limited is a part of Anaya Steel, LLC (US parent company). Our company has over 30 years of involvement in steel products. It mostly deals in:
- Specialized steel hardware – punched, pressed, galvanized, powder-coated.
- Steel pipes and tubing – specialized, color coated, galvanized, and structural.
- Our products are produced by Daiwa Lance International in Vietnam.
