How To Select A Magnetic Separator?
How To Select A Magnetic Separator?
Magnetic Separator Efficiency Criteria
Choosing the right magnetic separator requires careful evaluation based on specific efficiency criteria related to its intended purpose.
- For iron separators, it's crucial to achieve a high percentage of extraction of harmful impurities of various sizes that could damage crushing, grinding, or other equipment. Depending on the operating conditions—such as product layer height on the belt and conveyor speed—a suitable separator should be selected.
- Separators that recover saleable magnetic fractions like scrap metal or iron ore concentrates must ensure that the valuable component's content in the separated product meets required standards. The separator’s efficiency in eliminating non-magnetic impurities will directly impact the quality and cost of the final product.
- Another important criterion is the reduction of valuable product loss during separation. While complete elimination of losses is unlikely due to varying conditions and material compositions, a well-chosen separator can minimize these losses significantly.
For instance, the ERGA WetMag R wet magnetic separator for dense media recovery manages to maintain a loss rate of only 0.5 g per liter of processed suspension.
Properties, Composition of the Separated Product and Operating Conditions
When selecting a magnetic separator, it's essential to consider the properties and composition of the product to be separated, along with its operating conditions:
1. Product Size
The type and specifications of a separator are influenced by the size of the product being processed. The maximum size can reach up to 400 mm, while the minimum size is around 20-10 microns. For lumpy materials, separators with enhanced safety margins, like the ERGA DrumMag C and ERGA DrumMag M, are recommended.
2. Product Temperature
The choice of magnetic system alloy is based on the material's temperature. Standard permanent rare earth magnets operate effectively up to 60°C. For materials between 60°C and 200°C, Nd-Fe-B alloys with dysprosium and terbium are appropriate. For temperatures higher than 200°C, Sm-Co alloy-based magnets are recommended, which work up to 300°C.
3. Product Moisture
Moisture content is a critical factor for dry magnetic separation. For products smaller than 10 mm, moisture should not exceed 5%, while for less than 1 mm, it's 0.5%, and for sizes smaller than 0.1 mm, it should be at 0.1%. High moisture levels can hinder separation effectiveness due to particle adhesion to the separator's surface; thus, pre-drying is advised.
For reliable results, consider using a Zoneding machine.
4. Magnetic Susceptibility of Particles
The induction of the magnetic field in the operating area should suit the magnetic susceptibility of the particles. Ferromagnetic materials typically require separators with low magnetic field intensity (up to 0.32 T), while paramagnetic materials may require separators with medium (0.32-0.9 T) or high intensity (0.9-1.5 T).
5. Content of Magnetic Impurities
The percentage of magnetic impurities in the product will dictate the type of separator cleaning required. With a low percentage (below 0.5%), manual cleaning may suffice, while a higher content (0.5%-5%) calls for mechanical cleaning to streamline operations. When magnetic impurities exceed 5%, automatic cleaning becomes essential to prevent blockages in the working area.
Caution! Tricks of Unscrupulous Manufacturers
The growing market for magnetic materials, particularly from China, has led to an increase in manufacturers. Unfortunately, many lack the necessary expertise in producing quality separators. Suppliers often skip crucial quality control measures in an effort to cut costs, risking both efficiency and the durability of their equipment.