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Application: metal out of glass cullet

Getting aluminum and other non-ferrous metal out of glass cullet

In glass recycling the metal is the contaminant. Glassmakers want cullet with almost no non-ferrous metal in it, because aluminum spoils the melt and other metals harm the furnace. This page sets out the limits that apply, what arrives from a MRF, and the chain of machines that takes the metal out.

By [author name, role and employer] · Technical review by [reviewer name, role and employer] · Updated

  • Aluminum and non-ferrous
  • Ferrous
  • Fiber
  • Glass
  • Film
  • Other and residue

1Why metal matters in cullet

On a can line, aluminum is the product. In glass recycling it is the contaminant: the glass is the product, and the metal has to come out of it.

Aluminum spoils the melt. In the furnace it reacts with silica and forms small spheres of metallic silicon, which stay in the glass as inclusions. Source: EU Joint Research Centre (JRC), End-of-Waste Criteria for Glass Cullet, 2011, Table 3, citing Van Santen and Beerkens, 2005 (source 1).

A glass container maker's patent describes what follows. The silicon spheres cause stress fractures and weak glass, so more bottles come out defective. The patent traces the aluminum to closures, caps, aluminized labels and tamper-evident neck bands. Source: US Patent 5,620,491, assigned to Ball-Foster Glass Container Co., 1997 (source 2).

Metal also harms the furnace. Metals sink to the bottom of the furnace and can damage its walls and floor. Liquid lead drills down into the refractory floor. Source: JRC, 2011, p. 14 and Table 3 (source 1).

Experts told the JRC that non-ferrous metals shorten furnace life, so glassmakers consistently reject cullet over their limit. Iron does its harm mainly through colour, which is why the two are limited separately. Source: JRC, 2011 (source 1).

The metal taken out is not wasted. STEINERT, which sells glass sorting systems, says the non-ferrous metal separated from glass can be sold. Source: STEINERT, Hollow glass recycling, undated (source 3).

2Metal limits for cullet

Where a limit gives a figure, it is in parts per million (ppm), from 5 ppm for packaging glass in a CEN technical report to 60 ppm under the EU end-of-waste rules. Each limit below has its own scope, so check which one applies to your buyer.

Non-ferrous metal limits for cullet (each with its scope; they are not interchangeable)
LimitNon-ferrous metalScope
EU end-of-waste criteria, Regulation (EU) No 1179/2012At most 60 ppm. Ferrous metal at most 50 ppm.Cullet that is to stop being waste under EU law. Crushing, sorting, separating or cleaning must be complete.
Container glass: Glass for Europe figures, reported by the JRC20 ppm, for pieces over 0.1 g. Ferrous metal 50 ppm, for pieces over 0.5 g.Typical maximum for cullet going into container glass. Flat glass accepts essentially none; mineral wool, 20 ppm.
FERVER furnace-ready cullet specification, reported by the JRCAluminum 25 ppm and lead 35 ppmThe JRC says the EU's 60 ppm limit was taken from FERVER's specification. In the 2007 version the JRC reproduces, the aluminum and lead figures add up to 60 ppm.
CEN/TR 13688:2008, reported by the JRC5 ppmPackaging glass.
ReMA furnace-ready flint, amber and green cullet (US trade specification)Listed as prohibitive. No ppm figure is given.ReMA's container cullet grades are to be free of non-ferrous metal, apart from negligible amounts that cannot be avoided. Its unprocessed grades accept ring and metal closures as outthrows where processing permits, and its MRF glass grade counts closures as residue (section 3). The furnace-ready flint grade gives an ideal size of 3/8 to 3/4 in.

Sources: Regulation (EU) No 1179/2012, Annex I, read on the UK-retained copy, whose limits match the JRC's text of the adopted criteria (source 4); JRC, 2011, Tables 4 and 10 and p. 73 (source 1); ReMA, ReMA's ISRI Specifications, July 2026, pp. 28 to 30, with the ideal size on p. 29 (source 5; also on the 2022 furnace-ready flint cullet grade page, source 6).

ReMA's grades set no ppm figure for non-ferrous metal. A US figure: [US ppm figure for non-ferrous metal in cullet: a 2015 California evaluation, cited by the Glass Manufacturing Industry Council, still to be read].

ReMA's specifications are a common trading language. Buyer and seller may agree variations, and ReMA asks that any deviation be agreed and documented in writing. Source: ReMA, July 2026, preface (source 5).

Fitness for a particular furnace

Meeting a limit does not make cullet fit for every furnace. The JRC report behind the EU criteria says this of the limits it proposed, and leaves fitness for a given furnace to the contract between the cullet processor and the glassmaker. Source: JRC, 2011, p. 73 (source 1).

So the limit that matters is the one in your buyer's contract. Ask the glassmaker or cullet processor for its written specification before you set up the line. How other buyers treat aluminum as a contaminant is in aluminum scrap grades and what buyers accept.

3Glass from a MRF

Most modern MRFs take glass out early, to protect the recyclables further down the line. A MRF can raise the value of its glass by cleaning it before it goes to a beneficiation plant, the processor that turns it into furnace-ready cullet. Source: Glass Packaging Institute (GPI), Glass Recycling: A Quick Study, undated (source 7).

Some cans leave with the glass. Operators told a 2021 study of aerosol and pet food cans that items under 2 to 3 in across at least two dimensions can fall through the glass screen, including small and crushed cans. How much is lost is not known. Source: RRS for CMI, PFI and HCPA, 2021 (source 8). Where the glass screen sits on a MRF is shown in aluminum recovery on MRF container lines.

How much aluminum reaches a MRF's glass: [share of aluminum in MRF glass: no published figure found].

ReMA's grade for MRF glass shows how mixed the stream can be.

ReMA MRF glass (three-colour mix): what the grade tolerates
ItemUp to
Non-glass residue: paper, closures, labels, rock and dirt35%
Fines under 1/8 in30%
Ceramics2%
Moisture5%

Source: ReMA, ReMA's ISRI Specifications, July 2026, pp. 30 to 31: the residue includes metal and plastic closures, and p. 30 adds that fines this small cannot be sorted optically (source 5; also on the 2022 MRF glass grade page, source 6).

The Glass Recycling Coalition's certification for MRF glass, launched in 2019, evaluates a MRF's equipment and its glass quality. The coalition looks for glass purity of 75% or higher. Source: Resource Recycling, Processors open up on glass-sorting improvements, 2020 (source 9).

Some MRFs recover cans from their glass themselves, with a second eddy current separator on the glass discharge line or on the outthrow of a glass cleaning system. Source: CMI, Examples of MRFs Who Have Successfully Added Aluminum Can Capture Equipment, 2020 (source 10). What those operators reported is in where plants add recovery.

4The cleanup chain

A beneficiation plant cleans glass into cullet a furnace will take. The largest plants work cullet from about 3 in down to about 1/8 in, with crushing, air and optical sorting, and cleaning equipment. Source: GPI, undated (source 7).

The JRC's survey of cullet processing and one equipment maker's published chain describe the same stages. The table merges the two. Plants vary in the order and the number of stages.

Stages in cleaning cullet (the usual order; each stage with what it means for non-ferrous metal)
StageWhat it doesWhat it means for non-ferrous metal
1. InspectionLoads are checked by eye as they are tipped.
2. Magnet for lidsAn overhead magnet takes off steel lids and caps.Only ferrous closures come out here; aluminum ones go on with the glass.
3. ScreeningBroken glass is screened from whole bottles.
4. CrushingThe glass is crushed.Crushing frees more metal and plastic from the glass.
5. Drying or washing, and sievingOrganic matter is dried or washed off, and the cullet is sieved.
6. Magnets and eddy current separatorMagnets take out iron and steel. The eddy current separator throws out aluminum and other non-ferrous metal.The main non-ferrous step. Heavily contaminated loads may go through it more than once.
7. Air suctionDraws off paper and plastic, at several points along the line.
8. Hand pickingPickers take out foreign pieces by hand.
9. Sensor-based sorting by size fractionOptical sorters, each working on one size range, take out ceramics, stone and porcelain. The JRC reports that they reach 25 to 50 ppm of these, against 400 to 500 ppm by hand picking alone. X-ray fluorescence sorters pick out lead glass and glass-ceramic. Glass under 1/8 in is too small to sort optically (ReMA).
10. Final magnet and quality controlA last magnet, then automatic and manual checks.

Sources: JRC, 2011, section 2.2.4, for stages 1 and 4 to 10, and p. 14, citing Van Santen and Beerkens, 2005, for the 25 to 50 ppm figures (source 1); STEINERT, Hollow glass recycling, undated, the maker's own description, for stages 2 to 4, 6, 9 and 10 and for crushing freeing metal (source 3); ReMA, July 2026, p. 30, for the 1/8 in note (source 5). The two descriptions differ slightly in order: STEINERT puts further screening and the removal of organics after the separator.

Both descriptions pair magnets with the separator. The separator makers' manuals say where they go: ahead of it. IMI's manual says no magnet removes all ferrous metal, so one or more magnets should sit upstream, and that steel held in the rotor's field overheats and can weaken the rotor magnets for good. Eriez's manual, which lists glass among its separator's uses, also recommends magnets upstream where they are needed. Sources: Industrial Magnetics (IMI), manual 900505, undated (source 11); Eriez, RevX-E manual RM-99, 2015 (source 12).

This guide follows the separator makers' manuals: magnets go ahead of the separator, and the separator is not relied on to remove steel.

Magnet types and placement are in removing ferrous metal before the separator. Putting every machine in order is covered in designing an aluminum recovery line.

5Separators and sorters for cullet

Several makers publish models or ratings meant for glass. The table gives what each one says on its own pages. It is a sample, not a complete list, and it is not a ranking.

Glass models and ratings, as the makers publish them (makers' own figures; not tested by this site)
MakerWhat it publishes for glass
BuntingRates its HIC separator at up to 20 tonnes an hour per metre of belt width on 0 to 50 mm cullet, and its HIE and HIFE models at up to 7 on 0 to 30 mm crushed light-bulb glass. Bunting gives these as maximum capacities.
Industrial Magnetics (IMI)Its 12- and 16-pole eddy current separators were first designed for glass cleanup. It names 8-pole units for MRF work and pieces 2 in and up, and 16-pole units for pieces under 2 in. Nominal rotor speed is 1,760 rpm with 8 poles and 3,000 rpm with 16.
MSS (CP Group)Its MetalMiner induction sorter, in belt or chute form, sorts ferrous, non-ferrous and stainless metal down to 1 mm. Glass cullet is among its listed uses.
SGM MagneticsLists a GVIS separator for glass cullet, reinforced against abrasion.

Sources: Bunting, Eddy current separators product page, undated (source 14); IMI, Eddy current separators data sheet TG-13A, 2022 to 2023, for the pole counts and the glass-cleanup origin (source 13), and manual 900505 for rotor speeds (source 11); MSS, MetalMiner, undated (source 16); SGM Magnetics, Eddy current separators, undated (source 15). Industrial Magnetics supplies eddy current separators and magnets to Remcon Equipment, the publisher's affiliate.

Who publishes this. Recyclers Guide is published by [LLC name], an affiliate of Remcon Equipment, Inc. Remcon designs and builds conveyors and eddy current separator systems around rotors or complete separators made by others, builds overhead magnet units, magnetic head pulleys and trommels, resells screens and feeders, and integrates equipment discussed on this site.

How induction sorters and eddy current separators compare is in eddy current against sensor-based sorting. The sorters themselves are in sensor-based sorting for metals.

Small pieces

Small pieces of metal are the hard part. As a piece gets smaller, the force from the rotor's field falls faster than its mass, so friction takes over. Conventional separators lose effectiveness below about 5 mm. Source: Settimo, Bevilacqua and Rem, 2004 (source 18).

In bottom-ash plants, standard rotors at 2,000 to 3,000 rpm suit pieces above about 5 mm. High recovery of smaller pieces needs more than 4,000 rpm, more poles, or both. Source: Šyc et al., 2020, a review of bottom-ash plants (source 19).

Makers' smallest stated piece sizes, model by model, are in the eddy current reference. The routes for fines are in recovering fine non-ferrous metal.

Wear

Glass wears machines. Green Machine says its glass breaker takes glass and fines out early partly to cut belt and disc wear, and SGM says its glass separator is reinforced against abrasion. Sources: Green Machine, Glass breaker and fines removal, undated (source 17); SGM Magnetics, undated (source 15).

[First-hand: belt, shell and chute wear, rotor size and cullet size range on glass lines the publisher's affiliate has built for, and what aluminum its separators have taken out of cullet: questions for Remcon's shop]

Cullet's bulk density sets how much reaches the separator at a given belt speed. Published figures are in the bulk density reference, which feeds the belt feed-rate calculator.

What the publisher's affiliate builds

Remcon Equipment, the publisher's affiliate, builds trommels, conveyors and dumpers and resells screens that are used on glass lines. Its own pages describe that work: trommels, vibratory screens, dumpers and shuttle conveyors. Source: Remcon Equipment's own pages (source 20).

6What to tell the maker

Give every maker the same facts in the same order. For a glass line, these come from the sections above:

  • the cullet size range reaching the separator, after crushing and screening: IMI chooses its pole count by piece size (section 5)
  • the feed rate, and the belt width you have room for: Bunting rates capacity per metre of width (section 5)
  • what the metal is: caps, closures, labels, neck bands or can pieces (section 1)
  • moisture, and the share of fines under 1/8 in (section 3)
  • the metal limit in your buyer's contract, and how the buyer checks it (section 2)
  • how ferrous metal is removed upstream, and how many magnets do it (section 4)

The RFQ checklist covers the rest. Sizing an eddy current separator explains how width and model are chosen, and screening ahead of separation explains why the size range matters. Separator and sensor-sorter makers that list glass processing are in the directory.

7Questions

Why is aluminum a problem in glass cullet?

In the furnace, aluminum reacts with silica and forms small spheres of metallic silicon, which stay in the glass as inclusions. A glass container maker's patent adds that these spheres cause stress fractures and weak glass, so more bottles come out defective. Non-ferrous metals also attack furnace walls and floors and shorten furnace life. Sources: EU JRC, End-of-Waste Criteria for Glass Cullet, 2011; US Patent 5,620,491, 1997.

How much non-ferrous metal can cullet contain?

It depends on the rule and the buyer. EU end-of-waste criteria allow at most 60 ppm. For container glass, the EU JRC reports a typical maximum of 20 ppm for pieces over 0.1 g, and flat glass accepts essentially none. ReMA's US furnace-ready grades list non-ferrous metal as prohibitive without giving a ppm figure. Sources: Regulation (EU) No 1179/2012; EU JRC, 2011; ReMA, July 2026.

Does cullet that meets the limit suit every furnace?

Not necessarily. The JRC report behind the EU criteria says meeting the limits it proposed does not make cullet fit for every furnace, and leaves that to the contract between the cullet processor and the glassmaker. Ask your buyer for its written specification. Source: EU JRC, End-of-Waste Criteria for Glass Cullet, 2011.

What does ReMA's MRF glass grade allow?

Up to 35% non-glass residue, such as paper, closures, labels, rock and dirt; up to 30% fines under 1/8 in; up to 2% ceramics; and up to 5% moisture. ReMA notes that fines that small cannot be sorted optically. Source: ReMA, ReMA's ISRI Specifications, July 2026.

Where does the eddy current separator go in a glass cleanup line?

After the glass is crushed, with magnets ahead of it to take out steel. The EU JRC reports that heavily contaminated loads may pass the magnets and separator more than once. This guide follows the separator makers' manuals: magnets go ahead of the separator, and the separator is not relied on to remove steel. Sources: EU JRC, 2011; STEINERT, Hollow glass recycling, undated; IMI, manual 900505, undated.

Read the aluminum recovery guide Find manufacturers

8Sources

Figures from these sources are paraphrased, not quoted. Manufacturers' pages, data sheets and manuals state each maker's own claims; this site has not tested the equipment.

  1. European Commission Joint Research Centre (Rodriguez Vieitez, Eder, Villanueva and Saveyn). End-of-Waste Criteria for Glass Cullet: Technical Proposals, EUR 25220 EN. 2011. Government. publications.jrc.ec.europa.eu (PDF). Read 2026-10-06.
  2. Puhl, M. W., Dore, L. H., and Erb, R. L. Process and apparatus for decontaminating glass cullet. US Patent 5,620,491, assigned to Ball-Foster Glass Container Co. Filed March 8, 1995; issued April 15, 1997. Glass container maker's patent. patents.google.com. Read 2026-10-06.
  3. STEINERT. Hollow glass recycling (application page). Undated. Manufacturer. steinertglobal.com, hollow glass recycling. Read 2026-10-06.
  4. European Commission. Commission Regulation (EU) No 1179/2012, Annex I. December 10, 2012. Government (regulation). Read on the UK-retained copy at legislation.gov.uk; official text at eur-lex.europa.eu. Read 2026-10-06.
  5. Recycled Materials Association (ReMA). ReMA's ISRI Specifications, July 2026 edition: preface, and glass cullet, pp. 28 to 31. Trade specification. isrispecs.org (PDF). Read 2026-10-06.
  6. ReMA. ISRI Specs grade pages: Processed (furnace-ready) flint container glass cullet and Material recovery facility derived 3-color mixed container glass (MRF glass). Effective July 14, 2022. Trade specification. isrispecs.org, furnace-ready flint cullet; isrispecs.org, MRF glass. Read 2026-10-06.
  7. Glass Packaging Institute. Glass Recycling: A Quick Study (guidebook). Undated (2022 or later). Industry association. gpi.org (PDF). Read 2026-10-06.
  8. Resource Recycling Systems (RRS) for CMI, PFI and HCPA. Surveying State of MRF and End Market Barriers to Recycling Steel and Aluminum Aerosols and Pet Food Cans and Identification of Solutions. February 2021. Industry association, commissioned study. cancentral.com (PDF). Read 2026-10-06.
  9. Staub, C. Processors open up on glass-sorting improvements. Resource Recycling, July 7, 2020. Trade press. resource-recycling.com. Read 2026-10-06.
  10. Can Manufacturers Institute. Examples of MRFs Who Have Successfully Added Aluminum Can Capture Equipment. December 2, 2020. Industry association, operator statements. cancentral.com. Read 2026-10-06.
  11. Industrial Magnetics, Inc. (IMI). Eddy current separator service manual, endless belt, 900505. Undated. Manufacturer. magnetics.com, manual 900505 (PDF). Read 2026-10-06. Industrial Magnetics supplies eddy current separators and magnets to Remcon Equipment, the publisher's affiliate.
  12. Eriez. RevX-E eddy current separator installation, operation and maintenance manual, RM-99. April 2015. Manufacturer. eriez.com, RM-99 (PDF). Read 2026-10-06.
  13. Industrial Magnetics, Inc. (IMI). Eddy current separators, technical data sheet TG-13A. October 2022 to October 2023. Manufacturer. magnetics.com, TG-13A (PDF). Read 2026-10-06. Industrial Magnetics supplies eddy current separators and magnets to Remcon Equipment, the publisher's affiliate.
  14. Bunting. Eddy current separators (product page, with maximum-capacity table). Undated. Manufacturer. buntingmagnetics.com, eddy current separators. Read 2026-10-06.
  15. SGM Magnetics. Eddy current separators. Undated. Manufacturer. sgmmagnetics.com, eddy current separators. Read 2026-10-06.
  16. MSS (CP Group). MetalMiner. Undated. Manufacturer. mssoptical.com, MetalMiner. Read 2026-10-06.
  17. Green Machine. Glass Breaker & Fines Removal. Undated product page. Manufacturer. greenmachine.com. Read 2026-10-06.
  18. Settimo, F., Bevilacqua, P., and Rem, P. Eddy current separation of fine non-ferrous particles from bulk streams. Physical Separation in Science and Engineering 13(1), 2004. Peer-reviewed. repository.tudelft.nl. Read 2026-10-06.
  19. Šyc, M., et al. Metal recovery from incineration bottom ash: state-of-the-art and recent developments. Journal of Hazardous Materials 393, 2020 (postprint). Peer-reviewed. cris.unibo.it (PDF). Read 2026-10-06.
  20. Remcon Equipment, Inc., the publisher's affiliate. Its own pages, for the affiliate facts in section 5: rotating drum screens and trommels, vibratory screens, dumpers and shuttle conveyors. Read 2026-10-06.

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