Metallic contamination in food powder requires a magnetic separator. Contamination in powder processing enters product streams from multiple sources: wear particles generated during milling, fragments from mixer blades and paddles, fine stainless steel particles produced during conveyance and sieving. In high-volume dry processing operations — dairy, infant formula, flour milling, pharmaceutical powder — these particles are rarely visible to operators and too fine to be reliably captured by metal detectors alone.
Russell Finex Compact Sieve
The risk is particularly acute in infant formula manufacturing. Regulatory frameworks governing the composition and manufacture of infant formula are among the most stringent in the food industry — and for infant formula exported to China, an additional registration and certification regime applies above standard food safety requirements.
Magnetic separation addresses metallic contamination at the process level, capturing ferrous and weakly magnetic particles from product streams before they reach packaging.
How Magnetic Separation Works
Magnetic separators operate by passing a product stream through or across a powerful magnetic field. Ferrous particles — iron, carbon steel, and some grades of stainless steel — are attracted to the magnetic surface and held in place while clean product continues through the process. The strength of the magnetic field, measured in gauss, determines what can be captured: a low-gauss magnet will remove larger iron particles but may miss fine stainless steel wear debris. High-intensity magnetic systems operating above 10,000 gauss are designed to capture fine ferrous and weakly magnetic particles including stainless steel — which is the dominant construction material in food processing equipment and therefore the dominant contamination type.
In dry powder processing, magnetic separators are typically installed in-line within gravity feed systems, pneumatic conveying lines, or at transfer points between process steps. Positioning relative to contamination sources matters: a separator installed immediately after a mill captures the wear particles generated during size reduction; one installed ahead of a filling or packaging system provides a final contamination barrier before the product is sealed.
Russell Finex Magnetic Separator
The Russell Easy-Clean Magnetic Separator™
Russell Finex manufactures the Russell Easy-Clean Magnetic Separator™ for integration with powder sieving and screening systems in food, dairy, and pharmaceutical applications. The unit incorporates a high-intensity magnetic grid operating at 11,000 gauss, designed to capture fine ferrous and stainless steel particles that standard metal detectors cannot reliably detect at fine particle sizes. A deflector plate positioned above the magnetic grid directs product flow across the active magnetic surface, maximising contact between the product stream and the capture area.
The Easy-Clean designation reflects a design priority that is directly relevant to food and pharmaceutical production: the unit is engineered for rapid, hygienic cleaning without tools. In infant formula and dairy applications, cleaning protocols are demanding, cleaning cycles are frequent, and production downtime carries significant cost. Magnetic separators that require partial disassembly or specialist tooling to clean create a throughput constraint and a hygiene risk if cleaning is deferred or incomplete. The Russell Easy-Clean Magnetic Separator is accessible for clean-down without tools and is compatible with standard cleaning-in-place (CIP) and manual clean procedures.
The unit is designed for integration with Russell Finex sieving equipment including the Russell Compact Airlock Sieve™, Compact 3-in-1 Sieve™, and Finex® 22, allowing magnetic contamination capture to be incorporated as a step within the sieving system rather than requiring a separate standalone installation.
Contamination Sources in Powder Processing Lines
Understanding where metallic contamination enters a powder processing line determines where magnetic separation should be positioned. Milling is one of the highest-risk points: cone mills and centrifugal sifters operate at high speed under mechanical load, and equipment wear generates fine metal particles directly within the product stream. Hanningfield cone mills used for pharmaceutical and food powder milling incorporate no metal-to-metal contact drive designs to reduce this risk — but residual wear from screens and other wetted components remains a contamination pathway that magnetic separation downstream of the mill addresses.
Blending is a further risk point. Paddle and ribbon mixers operating at high fill levels can generate friction between agitator and vessel walls, particularly during start-up or when processing abrasive dry materials. Dinnissen Pegasus® Batch Mixers are manufactured with close tolerances that minimise metal generation during blending — but in infant formula production, where a single batch can represent many thousands of consumer servings, the consequence of a contamination event makes downstream magnetic separation appropriate regardless of upstream equipment quality.
Pneumatic conveying, transfer points, and gravity chutes can introduce particles from line components including valves, dampers, and flexible connections. Magnetic separators installed at multiple points across a line — after milling, after blending, and before packaging — provide layered protection consistent with HACCP-based contamination control.
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Infant Formula: Regulatory and Export Requirements
Infant formula produced in New Zealand for export operates within a layered compliance framework. Domestically, FSANZ Standard 2.9.1 governs product composition and labelling requirements. At the manufacturing level, a registered Risk Management Programme (RMP) under the Animal Products Act 1999 is required for any operator producing food products for export, including infant formula. The RMP must document all significant hazards — including physical contamination — along with the control measures in place for each.
For export to China — New Zealand’s largest infant formula market by volume — additional requirements apply. China’s current infant formula standards came into force in February 2023:
- GB 10765-2021 — infant formula for infants aged 0 to 6 months
- GB 10766-2021 — follow-on formula for infants aged 6 to 12 months
- GB 10767-2021 — young children formula for children aged 12 to 36 months
These standards govern composition, labelling, and manufacturing quality requirements for both domestically produced and imported infant formula. The manufacturing GMP standard GB 23790-2010 applies specifically to powdered infant formula production facilities.
Overseas manufacturers exporting infant formula to China must be registered with the China National Certification and Accreditation Administration (CNCA) and listed on the General Administration of Customs China (GACC) overseas food manufacturer registration system. In New Zealand, MPI administers this process: manufacturers must be registered via CIFER (China’s Import Food Enterprise Registration platform), and MPI issues the health certificates required by Chinese customs. MPI guidance document F13/26 sets out the specific requirements for NZ manufacturers applying for GACC registration.
Documented contamination control — including physical contamination such as metal fragments — is part of the manufacturing evidence that supports RMP compliance and ongoing GACC registration. A contamination incident in exported product can trigger import suspension, mandatory recall across all registered batches, and GACC registration review. Magnetic separation at documented control points within the manufacturing process is one component of the physical hazard control evidence that both domestic RMP requirements and Chinese import compliance demand.
Specifying Magnetic Separation for Your Process
Effective magnetic separation for infant formula and food powder applications requires specification matched to the particle size distribution of concern, the bulk density and flow characteristics of the product, and the specific control points in the process. Advanced Packaging Systems works with food and dairy manufacturers in New Zealand to specify and integrate Russell Finex magnetic separation equipment within powder processing lines. Contact us to discuss metal contamination control requirements for your application.
