Recovering Aluminum from MRF Residue: What Sorting Lines Miss
In September 2026, Waste Dive reported that Circular Services and Greyparrot were expanding a camera-based analytics pilot at a materials recovery facility (MRF) in Brooklyn, New York. The project aims to understand where recoverable aluminum remains in the facility's material flow. Its findings and technology belong to those companies; they are not results from CurrenTek equipment.
For other MRF operators, the practical question is familiar: after primary sorting, how much aluminum is still mixed with paper, plastic, glass and small residual debris? Recovering that metal requires a physical separation process matched to the residue, not simply another estimate of what might be present.
Why Aluminum Can Remain in the Residual Stream
Single-stream recycling delivers materials in unpredictable combinations. Flattened beverage cans, torn can fragments, foil-like pieces, steel closures, plastic packaging and paper may overlap or travel together. Some aluminum is missed because it is concealed, poorly presented or diverted into an unsuitable size fraction.
A residue stream also changes over a shift. Moisture, fines, feed depth and packaging composition can vary as collection loads arrive. An equipment setting that works on dry, loose fragments may behave differently with wet paper or compacted mixed waste.
Before planning additional recovery, the operator should sample the actual reject stream and establish the size, mass and accessibility of its aluminum. Metal still attached to other objects may require preparation before separation.
Prepare a Controlled Feed and Remove Steel
A trommel screen can classify mixed residue by particle size when a broad distribution prevents stable downstream feeding. The objective is not to send every fine particle to disposal: small aluminum pieces can be valuable, so each size fraction needs a defined destination.
Screens may clog with wet paper or film, and light flexible materials can move differently from rigid particles. Oversize objects and tangled items may need removal before screening. A facility handling already uniform material may not need a trommel at all.
Next, a magnetic separator can remove responsive iron and steel, including many food-can fragments and closures. This reduces ferrous contamination before non-ferrous recovery. Magnetic separation does not capture aluminum, and some stainless steels are not strongly magnetic. Installation distance and the depth of the feed layer also affect capture. CurrenTek
Recover Exposed Aluminum with Eddy Currents
An eddy current separator generates a changing magnetic field that induces currents in conductive non-ferrous pieces. The resulting force changes their discharge path relative to many non-conductive materials. In a prepared MRF residue fraction, it can help recover exposed aluminum pieces from plastic, paper and other light rejects.
CurrenTek lists eddy current separation for conductive non-ferrous recovery and confirms mixed packaging and UBC processing among its applications. That supports considering the technology for suitable prepared aluminum-bearing streams, but it does not establish performance at any particular MRF.
Particle geometry matters. Thin, light fragments may respond differently from rigid can sections, while damp material, clumps and thick layers can interfere with clean trajectories. The separator does not distinguish aluminum alloy grades or identify hidden metal through opaque packaging.
Test Whether the Extra Recovery Stage Pays
A pilot should measure both the aluminum captured and the aluminum left in the residual fraction. It should also record plastic and paper carried into the recovered metal, throughput stability, cleaning requirements and maintenance time.
The September MRF pilot illustrates the growing interest in identifying missed material, but camera-based waste analytics and physical eddy current separation are different functions. The former may reveal where losses occur; the latter can recover exposed conductive metal under suitable feed conditions.
The business case depends on saleable metal value, added processing cost and whether the recovered product meets a buyer's specification. A well-prepared residue stream and measured results are more useful than a universal recovery percentage.