Magnetic separation applications in the chemical processing industry are as diverse as the industry itself. The vast differences in chemistry among polymers, acids, rubbers, plastics, wet and dry chemicals, and pharmaceuticals are essential factors to consider when choosing magnetic separation equipment.
By Eric Confer
Each application presents unique challenges and not every piece of magnetic separation equipment is well-suited for every situation. This article guides readers in selecting magnetic separation equipment to meet their unique needs while satisfying protection, safety and reliability requirements, even when challenged by hazardous chemicals.
Advances in Magnet Technology
The chemical industry relies on magnetic separation products to recover fine iron contamination and reduce product wash off. Those needs led Eriez to develop its Xtreme RE7 Rare Earth circuit, which is now incorporated in the company’s tube and grate magnets. This technology surpasses previous models and competitive units with greater holding force, higher gauss, and improved separation efficiency.
The introduction of RE7 has had a direct impact on chemical product purity and productivity. The RE7’s high gauss is ideal for the chemical industry, where the level of inspection or ability to attract small metal pieces is most demanding.
A recent trend involves magnetic separation equipment now helping the chemical industry meet the growing demand for lithium-ion batteries. The need for new battery technology and the accompanying high-purity chemical components quickly surpassed the capabilities of standard magnetic separation technology. In response, Eriez introduced its Dry Vibrating Magnetic Filter (DVMF). It is specifically designed to remove extremely fine iron contaminants from fine powders such as lithium.
Eriez DVMFs are a great choice for both lithium producers and users. Producers pulverize lithium before it goes to the user as a very fine powder.
DVMF units (see video demonstration above) are placed prior to and after mill processing. As an additional check, users apply the DVMF when they receive lithium purchased from their supplier.
Dry Chemical Applications
Grate magnets, plate magnets, grates-in-housing, tube magnets and Dry Vibrating Magnetic Filters are often the best magnetic separation products for the job when it comes to dry chemical applications.
Product particle size determines which magnetic separator is most effective in removing fines and tramp iron. Refer to Table 1 for typical magnet uses in dry chemical applications.
Many standard-design products ship quickly and work well for a majority of dry process applications. They perform well unless the application includes harsh materials that degrade standard-duty materials. In these cases, Eriez uses superalloys, such as Hastelloy and titanium. The company has extensive expertise in producing magnets for applications that are dry with highly corrosive or unusual properties.
Wet Chemical Applications
Wet chemical applications require magnets to remove fine to large ferrous contamination. Selection is based on the diameter of the pipeline, the slurry or density of the liquid, the pressure of the flow and the required installation position. Typical specifications are shown in Table 2.
A U-trap is recommended when a liquid containing five or more percent solids is present. Implementing a U-trap ensures good flowability without impediment, while still eliminating a high percentage of the magnetic fraction. A High-Intensity magnetic filter, which is the liquid version of the Dry Vibrating Magnetic Filter (DVMF), may be specified for applications where a higher quality end product is desired. For example, this type filter can remove weakly magnetic particles for fine slurry product purification.
The Importance of Testing
While there are standard guidelines to follow when selecting magnetic separation equipment for chemical processing applications (as discussed in this article), testing using customers’ samples is the best equipment performance indicator.
The Eriez Central Test Lab’s capabilities include sampling, pilot testing and process development protocols. The Central Test Lab has a long history of proving the best-performing separation equipment and process for each unique chemical application.
Located in Erie, Pennsylvania, the Central Test Lab has more than 15,000 square feet of dedicated laboratory space and an array of lab and pilot equipment. The lab can perform product tests, provide detailed process analysis and create solutions for nearly any chemical application.
The chemical industry faces unique processing challenges, including protecting product purity and handling chemicals in the most efficient, economical and safe manner. Consequently, this highly diverse industry requires a multitude of magnetic separation equipment to handle dry and wet applications.