Casting Line

Refraco offers complete refractory engineering services for aluminium casting lines and their associated systems:

  • Inspections
  • Material evaluation and selection
  • Thermal studies
  • Complete design of new launder lines or launder line extensions
  • Fabrication and installation drawings
  • Technical specifications
  • Tender documents and forms
  • Launder Lines

    Molten metal is transferred from the remelt/holding furnace through a launder line to the casting machine. If the launders are not covered and heated, the metal cools as it travels the length of the launder line. Because casting machines require metal at a specific temperature, the operating temperature of the furnace is related to the thermal efficiency of the launder line. Therefore a thermally efficient launder line, allowing a lower operating temperature in the furnace, usually results in energy savings and reduced hydrogen absorption in the molten aluminium.

    When launders are not fully preheated, heat is absorbed from the molten metal until the launder line reaches equilibrium. This usually results in the first metal of each casting being drained off into pans until the temperature stabilizes and the metal can be redirected into the casting machine. The preheat temperature and the thermal efficiency of the launder line affect the amount of metal lost each casting and the time required before the system reaches equilibrium.

    The metal going into the casting machine must be free of "inclusions". The surface quality of the launders can affect the risk of refractory pieces being included in the metal flow.

    For a number of years Refraco has fabricated high quality refractory casting line launders.

    Through much time and energy spent on research and development, Refraco has developed forming and casting techniques that result in launders with an unparalleled quality of surface finish.

    Further, Refraco's specialized forming techniques reduce stresses on the launders during deforming. This reduces the occurrence of micro-cracks and permits the launders to retain their maximum mechanical and thermal shock resistances.

    Refraco casts launders in several different materials depending on the specific operating conditions. Different materials may even be used in the same installation according to the requirements of different "zones".

    Refraco's engineering department has developed a system of non-steady state heat transfer calculations that permit it model and optimize the thermal performance of casting lines based on different refractory, insulation and pre-heat configurations. They can also design the launder geometry to specific flow rate, maximum velocity and time of retention criteria.

    All of the above allow Refraco to provide high performance casting line launders, and complete casting line launders solutions, adapted specifically to client needs.

  • Filtration Equipment
    • Ceramic Foam Filter (CFF) Bowls

      “bowls” incorporated into casting lines. They are used for relatively coarse filtration of molten metal.

      Refraco designs and fabricates CFF bowls and/or the complete steel shell/refractory bowl system together.

      • Bowls can be fabricated in different refractory concretes, selected according to clients criteria, e.g. long life time, insulating value, metal penetration resistance (non-wetting).
      • Very smooth, non-porous surface finish.
      • Refraco's specialized forming techniques reduce stresses on the filter bowls during deforming. This reduces the occurrence of micro-cracks and permits the filter bowls to retain their maximum mechanical and thermal shock resistances.
    • Deep Bed Filter

      A Deep Bed Filter (DBF) is a fine filtration system using layers of alumina balls as the filter media. The system is comprised of :

      • A refractory lined box, divided into two chambers by a baffle.
      • Alumina pellets are placed on grid plates in the filter chamber, and sink plates are placed on top of the alumina pellets in the area underneath the entrance launder.
      • A preheat cover with a burner is used to heat the DBF to its operating temperature.

      The DBF is then transferred to the casting line and the preheat cover is replaced by another cover with electrical heating elements used to maintain the DBF at its operating temperature.

      Molten metal enters the DBF above the filter media, percolates down to and passes under the grid plates. The metal then passes under the baffle and rises through the exit well to the exit launder.

      Refraco installs the refractory linings and fabricates the grid plates, sink plates, and baffles for DBFs. Refraco also fabricates and installs the refractory and insulating parts for the preheating and maintaining DBF covers.

      • DBF Refractory Linings
        • Modular with relatively small panels and keyed joints.
          • Shorter dimensions improve crack control.
          • Limits crack propagation.
        • Hybrid pre-cast and cast-in-place.
          • Precast floor with smooth surface finish.
          • Cast-in-pace wall panels.
        • Unique one-way anchor system.
          • Allows the walls to expand and move during heat up and cool down, thereby reducing cracking due to constraints that are imposed by fixed anchor systems.
          • Only provides resistance against the walls bending towards the interiror, thereby reducing tension face cracking.
        • Extremely high strength refractory concrete with good thermal shock resistance and good non-wetting properties.
      • Grid & Sink Plates
        • Consumable parts replaced every time the bed media is changed.
        • Made of non-wetting refractory concrete with impeccable surface finish to reduce risk of inclusions.
        • Refractory with high mechanical resistance to reduce risk of damage during transport and during installation.
        • Made to measure for different DBF sizes and configurations.
      • Baffles
        • Removable/replaceable part.
        • Refractory concrete with high thermal conductivity to reduce temperature gradient between the filter chamber and the exit chamber.
      • DBF Preheat and Maintaining Covers

        Refraco fabricates the following components for use in DBF covers:

        • Burner Blocks
        • Blanket Modules
  • Degassing equipment

    Degassing is an important step in the production of aluminium. Aluminium quality can be improved by removing hydrogen gas, the only gas soluble in molten aluminium. Degassing equipment is inserted into the launder line between the furnace and the casting machine. Degassers are commonly lined with refractory tiles similar to the rest of the launder line. However, because of the added turbulence of degassing processes, these tiles are subject to more wear.

    Baffles are used at the entrance and the exit of the degasser to create a gas pocket above the molten metal within the degassing unit. The air in this gas pocket is replaced with an inert gas, often argon, to limit oxidation of the aluminium during the degassing process.

    Refraco fabricates the refractory launder tiles and baffles to line degassers that provide:

    • High wear resistance
    • Resistance to chemical attacks (i.e. non-wetting to aluminium)
    • Low maintenance and easy cleaning

For more information about Refraco's products, get access to our specification sheets from the Member Zone.