Welcome to Zmag

The benefits of using stirrers in the recycling and reclamation of aluminum are recognized throughout the industry:

Productivity Use of a stirrer quickly and efficiently brings the entire batch up to optimal temperature, minimizing the melting time and energy spent on the process and maximizing furnace productivity.

Recovery and Melt Loss Aluminum oxidization is minimized due to the increased melting speed and elimination of need to over heat the bath. This brings an increase in recovery and a reduction in melt loss.

Dross Efficient melt means less dross generation.

Environmental-friendliness Due to an increase in melting speed and decrease in use of burner fuel (e.g., natural gas), there is consequently less greenhouse gas emissions.

Uniformity For consistent and predictable product quality, molten aluminum must be thoroughly mixed from top to bottom.

Safety Elimination of the need for manual stirring results in higher safety.

Traditional Technologies
Stirrers can be categorized into two areas:

Pumps

Mechanical Pumps
Mechanical pumps are the most common form of molten aluminum circulation technology used in the industry today, especially in the US. However, while mechanical pumps have a low upfront cost, they suffer from several inherent design deficiencies:

Mechanical pumps require direct contact with molten aluminum. Physical contact wears parts. A typical cost of maintenance and consumable parts can range from $60,000 to $200,000 per year per system.

Mechanical pumps have a small circulation capability and require special install parameters. Furnaces are required to maintain a certain aluminum depth so that mechanical pumps do not suck-in air and oxidize molten aluminum. Pre-heat of the equipment is also required before installation.

Electromagnetic Pumps
A typical electromagnetic pump is a tube type pump surrounded by copper coils. Since the tube has a small diameter of around 6 inches (152 mm), tube clogging becomes one of the major issues users face. In addition, due to the limited size of the tube, the only way to increase the circulation volume is to increase the molten aluminum velocity. This causes unwanted molten aluminum turbulence which leads to aluminum oxidization and an increase in melt loss. A tube type electromagnetic pump also requires a minimum molten aluminum depth before it can be operated. The coils surrounding the tube are necessary because magnetic field/force is generated by running electricity in the coils. This means the coils are generating heat, and therefore, a water pump is required to protect the coils. If the coils are damaged, replacing them is very costly.

Stirrers
Electromagnet stirrers
While electromagnet stirrers are more suited than mechanical pumps for use in large industrial applications, they also are noted for having significant design deficiencies:

Electromagnet stirrers are complicated, a system unto themselves. They require transformers, special control panels, piping, liquid cooling (typically) and fine install tolerances.

Electromagnet stirrers come with copper coils to generate magnetic field/force to circulate molten aluminum. In order to generate magnetic field/force, electricity has to be run in the coils. In other words, electromagnet stirrers generate heat within their systems, and therefore typically require a water pump to protect the coils. Maintaining the coils and water pump (to de-mineralize water) is challenging and time consuming. If the coils are damaged by heat, replacement and maintenance costs are high. Electromagnet stirrers have high electrical, running and ongoing maintenance costs, not to mention that high electricity means generation of greenhouse gas such as CO2.

Because of these issues, Electromagnet stirrers cannot easily be retrofitted onto existing furnaces.

The Solution: Magnet Stirrer

As an alternative and solution to the issues associated with mechanical pumps and electromagnet stirrers, Zmag has developed a magnet stirrer run by a permanent magnet drive. Zmag’s Magnet Stirrer features a revolutionary and patented design which is scalable, efficient and cost effective. The technology provides contactless stirring of molten aluminum and can be easily adapted for use in existing furnaces.

Zmag’s stirrer is the world's first stirrer using a permanent magnet circuit for molten aluminum furnaces. This technology requires only 5 – 10% of the electricity needed to operate conventional electromagnet stirrers while providing for a superior and uniform circulation of molten aluminum. There is no direct contact with molten aluminum and no need to maintain copper coils and a liquid cooling system. Courtesy of the permanent magnet drive, Zmag's Stirrer is virtually a maintenance-free product.

Customers can expect to see an immediate increase in productivity, recovery, melting speed and uniformity throughout the molten aluminum while at the same time realizing significant savings in running costs, particularly a savings in fuel.

From a cost, performance and maintenance perspective, Zmag’s stirrer is the best choice for stirring molten aluminum.

Benefits are gained immediately following installation:

Before and After Zmag's Stirrer Installation

	Before installation	*After Installation*
Temperature Difference in Molten Aluminum	68℃ (154.4F)	Less than 5℃ (41F)
Recovery	90%	92%
Si Dissolution Time	2 Hours/4t	45 Minutes/4t (62.5% down)
Raw Material Dissolution Time		Shortened by 25%
Specific Fuel Consumption	135 l/t	105 l/t (22.2% down)

Series II, 50t (110,229lb) Reverberating Furnace

Temperature Distribution

Comparison between Electromagnet stirrer and Zmag's Permanent Magnet stirrer

	Electromagnet stirrer	Zmag
Electricity (Rated Value)	50～400kW	2.2～30kW
Cooling System	Water-cooled system (demineralization)	Air-cooled system
Magnetic Field Strength	200～250G	250～510G
Weight	～20,500kg	～4,100kg

Click here to see a case study on Zmag’s stirrer installation and operation at New Zealand’s MCK Metals Pacific Ltd.

Excerpt:
After installing a permanent magnet stirrer in their gas-fired furnace, the aluminium extrusion and fabrication manufacturer is saving 6.8 percent in gas energy consumption. The Z-Mag stirrer, which uses permanent magnet technology, is the first of its kind to be installed in Australasia. Unlike electromagnet stirrers, which create a magnetic field using an electric current, the Z-mag requires minimal energy to operate. In addition to the signifi cant reduction in gas consumption, the stirrer is also delivering other benefits including improved product quality.

Click here to see a further report on this installation.

Products

The stirrer comes in several models and configurations:

Series I

The Series I is for small furnaces and crucibles, in a floor type configuration. Series I is designed for maximum ease of installation, fitting under a standard furnace and within the existing factory environment with little adjustment.

Series II

Series II is for canal configurations. With a canal, molten aluminum flows around the stirrer, providing for precise control of flow speed and direction. The canal area can also be used for alloying.

Series III

Zmag's Series III is an all-in-one solution with no external requirements or dependencies. The unit is air-cooled and comes complete with a standard blower and simple control panel. The Series III is highly adaptable and easily installable.

Series IIIF. The IIIF is a floor mounted unit meant for placement under a furnace. The IIIF is similar but larger than the Series I and is ideal for tilting furnaces, either in a pit or attached to the furnace bottom.

Series IIIS. The IIIS is a side mounted unit. The advantage of this configuration is that vertical installation next to the furnace allows the magnetic field to cover the entire molten aluminum depth, providing for quick startup circulation and movement of the entire bath.

Series IIIS-H. The IIIS-H is a side mounted unit with the magnet circuit mounted in a horizontal configuration. A horizontal configuration rotates and moves molten aluminum from the bottom of the bath to the top (or vice versa).