PARTICLE SORTING OF LIGHT-METAL ALLOYS AND EXPANDED USE OF MANUFACTURING SCRAP IN AUTOMOTIVE, MARINE AND AEROSPACE MARKETS

Transcription

1 PARTICLE SORTING OF LIGHT-METAL ALLOYS AND EXPANDED USE OF MANUFACTURING SCRAP IN AUTOMOTIVE, MARINE AND AEROSPACE MARKETS Adam G G C Hartmut Harbeck TiTech GmbH

2 Value-added markets: Al-intensive vehicles

3 Value-added markets: Al-intensive vehicles

4 Value-added markets: Al-intensive vehicles

5 Value-added markets: Al-intensive vehicles

6 Value-added markets: Al-intensive vehicles

7 Use of Al- and Mg-based alloys in automotive components Parent Al Mg Alloy 38X.0, 319, 356 A , , , 6082, 7004, 7008, /4147, 3003/4147 AMxy, AM60 (Mg-Al-Mn) AZxy, AZ91 (Mg-Al-Zn-Mn) AJ62 (Mg-Al-Sr-Ca) AE41, AE44 (Mg-Al-RE) Application power train castings cast wheels closure sheet stiffener sheet extrusions brazed heat exchangers x<4 sheet and extrusions x>4 castings Creep-resistant castings

8 Value-added markets: Al-intensive vehicles

9 Value-added markets: Al-intensive vehicles

10 Al alloys dominant in marine market Alloy Family 5XXX 6XXX 6061, 6063 Alloys 5052, 5X56, 5X83, 5X86 Applications sheet and plate: hulls, superstructures extrusions: spars, structural stiffeners

11 Value-added markets: Al-intensive vehicles

12 Value-added markets: Al-intensive vehicles onsultants Inc

13 Use of Al- and Mg-based alloys in aerospace components Alloy Family Al + Cu Al + Zn Al + Li Al + Mg Al + Mg + Si Mg + Al + RE Alloy 2X14, 2X19, 2X , 2X , , 7X50, 7X75 7X50, 7055, 7X , 2X95, 2090, 2X98 2X96, , AE41, AE44 Application sheet and plate extrusions sheet and plate extrusions, sheet sheet and plate extrusions sheet extrusions sheet and plate creep-resistant castings

14 Secondary die castings

15 Oxides Salts Aluminum production and recycling Shredde r residues RSI Dross processor EoL & mixed metal scrap Foils Chips Turnings Contaminated scrap Shredder Sorter Scrap dealer Landfill Al shred Dross Handsorted Al scrap Mixed manuf scrap Assembly scrap EoL scrap Prime smelter Remelt and ingot casthouse Semifabricator Component manufacturer Waste Assembler Use Fab scra p Manuf scrap Casting scrap Shape caster Reject components

16 Quantities of new fabrication and manufacturing scrap A mass balance of global Al flows done around 2005 demonstrated that new scrap represents >50% of prime metal production at ~21,000 kt. This was three times as much metal as was recovered from old post-consumer scrap. Mg-based alloys consume currently ~300 kt of prime Mg and result in ~200 kt of die trim and machining chips. New scrap has a significant advantage over postconsumer scrap in that it is already collected at the fabrication and manufacturing locations, is generally more predictably contaminated, and is not corroded.

17 Production and manufacturing scrap sources Primary smelter dross Remelt and secondary smelter dross and skim Ingot/billet casting scrap Shape casting scrap Semi-fabrication scrap Manufacturing scrap Prompt and manufacturing scrap quantity is large (~3 old scrap). Metal production and semi-fabrication scrap either is or should be alloy segregated at source. Manufacturing scrap often is a simple mixture of known metals and alloys. Scrap is usually surface contaminated: oily, lubricated or coated with paint, paper or plastic. Scrap should be cleaned, preferably before sorting, but definitely before remelting. All metal separated from production or manufacturing scrap is already recycled, some of it closed-loop into a similar alloy.

18 New scrap New scrap generation has immediate financial impact on product component costs. Manufacturers purchase metal for their products and the resulting scrap at a high price that includes the cost of production of the prime metal, and all metal fabrication steps Manufacturers then sell the new scrap at a discount to prime metal. The size of the discount depends on how clean the scrap is and if it is segregated by alloy or sold as a mixture. In this way scrap generators pay more, while scrap recyclers could the benefit of the discount when they batch secondary alloys from scrap.

19 Segregation by alloy at source At source, the composition of each alloy is known to a better precision than can be determined by on-line sensors. Segregation by alloy at source is always preferable to later sorting. Alloy segregation is typically practiced at the semifabrication plants. Mistakes and mix-ups still sometimes happen. Logistically, scrap segregation by alloy is difficult in large machining shops and stamping plants. When source segregation is attempted, mistakes often happen.

20 Mixed-alloy scrap Occasionally mixed-alloy new scrap has an average composition that is compatible with an alloy with a higher alloying element content, and can be used directly in batching this alloy without sorting. This is a case for used beverage cans, where the average can composition can be used for batching the can body alloy. However, these cases are exceptions, and more commonly new mixed metal scrap is sold at a discount to be used later for secondary foundry alloy or painted building sheet applications. To recover full material value and keep this metal in marine and automotive wrought product markets, sorting of mixed scrap will usually be necessary.

21 Sorting technology current commercial practice

22 Chute type particle sorter Unsorted particle feed 2 Scanning and processing 3 Diversion 3

23 Belt type particle sorter Unsorted particle feed 2 Scanning and processing 3 Diversion

24 Sensors suitable for scrap sorting tasks There are a number of sensors that can remotely inspect and analyse particles distributed on a conveyor belt, sliding down a chute or in free fall. Vision 2-D and 3-D sensors identify shape and size of individual particles. In new scrap there may be a consistent correlation between the metal/alloy type and the shape/size of scrap pieces. In cases where such a correlation exists sorting by shape is one of the most cost-effective options. Colour or gray-scale sensors identify painted particles and contaminants and sort by parent metal (Mg, Al, Zn, Cu, Fe). Sometimes, during a pre-cleaning step, the scrap surface is chemically altered to selectively tint different alloys in the mix. X-ray transmission sensors are able to look through light-metal particles. This enables the sensors to identify attachments or contaminant particles; sort by wall thickness; separate light metal from dense metal; Al from Mg; and Al alloys with Mg or Si only from Al alloys that contain dense alloying elements such as Cu and/or Zn.

25 Finder Eddy-current coil sensor sorter Find metal in residue and/or separate stainless steel Mixed feed ECC sensor Sorted Products Potential for grouping some non-ferrous metals Conveyor Air jet ejection

26 CombiSense Color and ECC sensor sorter Separate Cu, brass, Zn, stainless steel, nonmetal Mixed feed Illumination Color sensor Sorted Products or Al, Mg and nonmetal Conveyor ECC sensor Air jet ejection

27 X-Tract dual energy x-ray transmission sensor sorter Identify contaminants, Mixed feed X-Ray Illumination Sorted Products attachments, separate light metals from dense metals Conveyor DE sensor Air jet ejection

28 DE-XRT identification of Al and Mg

29 Elemental composition sensors Elemental composition sensors enable separation of alloy mixtures that are not separable by physical shape or colour or X-ray absorption. For new scrap mixtures consisting of few known alloys, calculation of the actual elemental concentrations is not necessary. It is adequate to base the sort on the alloy spectral fingerprint. This significantly simplifies the complexity of the sorting task, as compared with trying to batch an alloy from a mixture of scrap particles of many unknown alloy compositions.

30 Elemental composition sensors: X-ray fluorescence sensor (XRF) Used for discrimination based on high (>18) atomic number alloying elements. In air XRF can remotely sense characteristic x-rays from Ti, Mn, Fe, Cu, Ni, Zn and denser elements. Air absorbs low-energy x-rays from light metal elements such as Li, Mg, Al and Si. XRF sensors have limited usefulness for Al- and Mgbased alloys.

31 Elemental composition sensors Laser-induced plasma spectroscopy (LIBS) The optical emission from a plasma spark generated by the ablation laser impact is spectroscopically analysed. All alloying elements of interest can be detected by optical emission spectroscopy. LIBS technique is used where discrimination based on light alloying elements (Li, Mg, Al and Si) is necessary.

32 Elemental concentration sensor sorters Mixed feed X-Ray Illumination XRF array sensor Sorted Products XRF sensor Alloy sort based on analysis of dense elements Conveyor Air jet ejection LIBS sensor Alloy sort based on analysis of all elements, light and dense Mixed feed LASER OE Illumination Spectrometer XYZ scanner Camera Conveyor Sorted Products Air jet ejection

33 Competition: Sorting table vs Sorting circuit

34 Sorting circuits In order to provide sorted products with an acceptable combination of recovery and product purity, sorters are arranged in a circuit with auxiliary unit operations. A typical dry sorting circuit for light-metal scrap might include following unit operations: Particle sizing size reduction and size separation Clean and dry removing cutting fluids and forming lubricants from new scrap Sort out non-al contaminants from Al-alloy mix Sort mix by alloy or batch target alloy(s) from the mix

35 LM alloy batching/sorting plant Mg Mg + Al Contaminated DE x-ray sensor particle sorter circuit HP hammer mill Oversize >3<9 mm Oversize 30 mm 9 mm fines screens >9<30 mm <3 mm fines >30<100 mm Al-alloy mix Mg-alloy mix Clean LIBS sensor elemental composition particle sorter circuit >9<100 mm Mg / Mg+Al / Al Overbelt magnet Headpulley magnet Eddy current rotor circuit steel attached steel stainless steel Dense Metals Al alloy 1 Al alloy 2 Alalloy mix Mg alloy 1 Mg alloy 2 Mgalloy mix >3<9 mm Al mix >3<9 mm Mg mix Nonmetal steel Al fines Mg fines

36 Sorting circuit 0 Product Grade (%) 100 Sorter Circuit Optimum Performance Curve Feed mix Prepare Feed PS product Clean product mix PS Clean Residue mix 0 Component Recovery (%) 100

37 Scrap sorting plant (current technology) Dense metal mix (dense media sink) Dense metal mix (dry sort) Al + Mg (light media float) >9<100 mm metal mix DE X-ray sensor particle sorter circuit Dense metal mix Color sensor particle sorter circuit Red Whit XRF sensor e elemental composition particle sorter circuit HP hammer mill Oversi ze >3<9mm Scale and radiation detector Oversize 30 mm 9 mm fines screens >9<30 mm Overbelt magnet Headpulley magnet Eddy current rotor circuit >3<9 mm metal mix >30<100 mm <3 fines steel attached steel stainless steel Nonmetal lead wire stainless steel Eddy current coil particle sorter circuit DE X-ray sensor particle sorter circuit attached steel reshred Al Mg Cu red brass yellow stainless Zn lead brass steel wire nonmetal steel

38 Desirable and feasible separations for new scrap: Impurity removal Impurity separation from purchased new scrap, nominally alloy-segregated at source (nonmetal, other metals, other alloys of the same metal, pieces with other attachments, dirty, painted or coated) from (2024, 3003, 5754, 5182, 5052, 5083, 5086, 6061, 6082, 6022, 6111, 6016, 7004, 7008) Small quantity of impurity from large quantity of good material. Economic for small particle sorting. what nonmetal other metal other alloy pieces with attachments dirty, painted or coated Remove eddy current rotor colour, XRT, eddy current coil XRT, LIBS,XRF XRT colour how

39 Desirable and feasible separations for new scrap: Sorting of new scrap Sorting among known alloys of new, mixedalloy scrap Similar quantities of known alloys. Economic for sorting of larger particle. Stamping skeletons: Automotive: 6111 from 5754 Cutting trim: Machining chips, turnings 6063, 6061 from 2024, 7050, 7075, 356 from 319, 38X Al from brass, st. steel, zinc Sprues, gates, mold trim, 356, 319, 38X, 413 what Aerospace:2024 from 7050 & from 7075, Marine: 5083 from 5086 Sort how LIBS LIBS XRT, color XRT, LIBS

40 Conclusions Manufacturing of aerospace, marine and automotive components results in generation of large quantities of new scrap. Source segregation of scrap by alloy is desirable but often not practical Sorting of scrap to maintain its value is usually more cost effective than Sorters that can identify and remove impurities are already commercially available and proven in large tonnage industrial applications. Sorters that enable sorting by alloy have also been proven and commercial units are under development.

41 Conclusions Source segregated fabrication scrap is routinely used in batching aerospace marine and automotive alloys Sorting of new scrap mixed manufacturing can significantly increase the quantity of light metal scrap that is practical to use as starting material for value added alloys for production of cars, boats and airplanes.

42 Thank you Manufacturing Construction Assembly Consumer Semi-product fabrication Collection & de-pollution Material production Mechanical segregation Feedstock production Energy recovery