Secat, Inc.

Providing Aluminum Answers

Secat TechTalk: MagStir

MagStir™, the world’s first permanent magnet stirrer for molten aluminum was introduced by Zmag,Ltd.(Japan) in 2004,followed by the Typhoon™ chip melter and all oyerin 2009. Over 100 systems have been installed and are running around the globe at small cast houses aswell as global primary and secondary aluminum producers. However, misunderstandings and misconceptions persist with regard to these technologies, so this article addresses some of the most commonly asked inquires.
Q: What are Zmag’s MagStir and Typhoon?
A: Mag Stir is the world’s first and only permanent magnet stirrer to circulate molten aluminum. Typhoon is the world’s first and only permanent magnet aluminum chip submerging system.Both Mag Stir and Typhoon are powered by the zPMC™.
Q: What is the zPMC?
A: Zmag Permanent Magnetic Circuit, aproprietary technology Zmag has developed and designed to move molten aluminum.
Q: Do you need electricity to generate magnetic fields as a traditional EMS(ElectromagneticStirrer) does?
A: No. The zPMC is a “permanent” magnetic circuit. The magnetic field exists naturally as a function of the design, without requiring electricity.
Q: Then, why do Mag Stir and Typhoon need electricity?
A: A small amount of electricity, as low as 3kW/h (4HP) and up to 2 0+kW/h (27HP),is used to rotate the zPMC via a gear motor. Electricity is also required to run a small air blower (2.2kWor3HP)  which protects the zPMC from molten aluminum heat.
Q: Similar to a traditional EMS, do you need components like a transformer, a frequency convertor, piping, a complex control panel, and fine installation tolerances to run the MagStir/Typhoon?
A:  No.The control panel is compact and simple, and many customers integrate the MagStir/Typhoon control functions into their furnace control panels. The MagStir/Typhoon does not require a PLC.The zPMC is turned with a simple inverter control.
Q: What are molten metal flows in comparison with EMS?
A: The largest flow rate of the Mag Stir observed (todate) is over 90T(about200,000LBS) per minute. Most furnaces do not require this level of circulation; however, the MagStir is customized to meet customers’ needs. An EMS generates wave motions when moving molten aluminum where as the MagStir is designed to quietly move a large amount of molten aluminum under the molten aluminum surface skin.By doing this,the Mag Stir ensures to minimize a chance of oxidizing molten aluminum while maximizing heat transfer efficiency. Customers can flexibly change flow rates and direction (e.g. clockwise and counterclockwise) of molten aluminum via the inverter.
Q: What is the estimated life of th ezPMC?
A: If the air blower is running all the time to protect the zPMC from heat from molten aluminum, there is really no noticeable performance loss over a long period of time.The zPMC does not generate heat in its permanent magnetic circuit and only needs to be protected from molten aluminum heat.
Q: What is a typical operational temperature?
A: This varies among operations,however, it is typically between 35 degrees Celsius and 85 degreesCelsius(95-185Fahrenheit). The MagStir/Typhoon control panel is preset to send a warning if an ambient temperature of the zPMC hits100degreesCelsius(212Fahrenheit). In this case,operators should confirm that the air blower is running properly.
Q: What kind of maintenance is required?
A: Maintenance requirements are so low that Zmag needs to remind its customers to check the system. Bearings need to be lubricated,and the gear motor oil should be changed on a periodic basis. Since the zPMC turns slowly (typically up to 60RPM), little stress is placed on the bearings.
Q: What about magnetic field safety?
A: The zPMC is designed to focus towards molten aluminum. Other directions are magnetically-shielded, to roughly the level of a kitchen magnets strength. However operators with a medical device implant should not approach the vicinity of the MagStir/Typhoon. Watches, credit cards, and other magnetically-affected materials should also be kept away from the MagStir/Typhoon.
Q: Can we retro fit the MagStir/Typhoon to our furnaces?
A: Yes. Each MagStir/Typhoon is customized to meet specific objectives of customers and can be retro fitted to various types of furnaces.
Q:What benefits should I expect to see if Iuse zPMC-powered products at my plant?

A:Since every customer’s objectives, furnace configuration and operation are different, Zmag does not make specific claims about the benefits of MagStir and Typhoon. However ,below is are ference courtesy of Rio Tinto’s Pacific Aluminium New Zealand Aluminium Smelters.

  • Drop in dross generation: 25% conservatively across heavily alloyed product.
  • 50% reduction in the skimming and stirring time for alloy additions compared to manual stirring.
  • Extended refractory life between major refractory rebuilds.
  • Reduction in operating costs such as fork lifts and manual stirring tools as well as reduction in personnel safety risk.
  • Reduction in fuel by 7% (and associated CO2 emissions).
  • Consistent and predictable product quality through improved alloying capability, especially in Ti recoveries as well as significan treduction in magnesium burning on molten aluminum surface.
  • Improved temperature homogeneity with top to bottom temperature differential constantly at +/-2 degrees from its set-point.
  • Reduction in the likelihood of temperature related casting defects by having the temperature constant against depth of the metal in the furnace.
  • Improved melt quality in the furnace resulted in a significant increase in the product quality as the product is not as susceptible to inclusions,dross entrapment or spinel generation.
  • Constant stirring has increased some alloy code casting from 6 to 7 casts in a 24hrday (a 16.7% increase).

For more information about Zmag, email them at info@z-mag.net or visit www.z-mag.net

For more information, please contact Todd Boggess attboggess@secat.net or 859-514-4989.

#WeLoveAluminum

May 30, 2016 - Posted by | Blog Posts

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