From Scrap to Ingot. Titanium scrap recycling via cold hearth melting. Dieter Kaufhold, ALD Vacuum Technologies, From Scrap to Ingot

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1 From Scrap to Ingot Titanium scrap recycling via cold hearth melting

2 Scrap as raw material source Global estimated aerospace titanium scrap market is around 80,000 MT Importance of scrap as raw material source is growing Scrap is the cheaper source for Titanium material Maximizeing scrap content minimizes cost of melting State of the art closed loop scrap strategies aim to keep high quality scrap within the high quality material supply chain typical case: aerospace material Upstream consolidation of Titanium producers stretches scrap collection from melting, forging, casting, rolling, machining, finishing,. Future outlook: with near net shape fabrication processes getting mature buy to fly ratios will decrease and specific scrap rates are assumed to decrease accordingly

3 Scrap characteristics Generally two scrap sources: home scrap and purchased scrap on the market Use of home scrap provides best yield for material and money All alloy grades from industrial cp to PQ rotary grade Loose agglomerate scrap: Machining scrap form turning, milling, cutting, grinding high volume and low bulk density Bales or compacts of agglomerate/machining scrap in order reduce the high volume of the low bulk density scrap (e.g. compacted turning scrap) Bulky scrap from forging, rolling, casting, cutting with a wide range in big sizes and heavy weights.

4 Typical loose agglomerate scrap cobbles sheet castings chunks compacts Typical maximum size 100 x 100 x 100 mm fed into the melting hearth via drum feeders / Archimedes screw feeders vibratory feeders

5 Typical large sized bulky scrap forging ends slab ends cutting scrap rotor scrap fed into the melting hearth via horizontal scrap electrode feeder bar feeder for scrap boxes

6 Examples for scrap electrodes

7 Possible scrap pre treatment steps scrap material intake, weighing and inventory documentation Separation between bulky and agglomerate scrap Sorting by alloys via various analyzing systems, classification scrap material preparation (e.g. cutting, shearing, shot blasting, pickling, ) Blending, mixing with alloying elements to adjust chemistry Eventually compacting /balling (reduction of volume or creation of defined chemistry in a compact for alloy production) Scrap mixing and blending Analysis of blend prior to CHR melting in button melt furnace to verify chemistry

8 cold hearth scrap melting metallurgical and process requirements State of the art Ti scrap melting is cold hearth melting ( CHR) Removal of HDI (high density inclusions) = removal by gravity and entrapment in skull (e.g. tungsten carbide particles of machining tools, molybdenum, tantalum) Removal of LDI (low density inclusions = hard alpha inclusions ) = removal by dissolution using superheat and sufficient residence time of (e.g. TiN 2 ) Achieve required chemistry and homgenity Lower gaseous impurities and improved structure Constant process parameters with respective data logging for quality assurance (e.g. process pressure, temperature distribution, casting rate,.) Two alternative processes for cold hearth melting available: EB and PAM

9 Scrap melting EB CHR Energy source Electron Beam Gun (EB gun) Main application cp grades / Ti 6 4 Melting under high vacuum (0,5 Pa 10 2 Pa) Good degassing and refining capabilities but increasing loss of volatile elements Very sensitive/critical against all kinds of unstable process conditions Salient feature: very flexible in casting geometry ( e.g multi strand / double cast slab) Very flexible in regards to size and geometry/shape of casted final products High productivity especially for cp grades (melt rates up to 4mt/h) Very large bulky scrap pieces can be melted by scrap electrode feeder (approx. 700 x 700 mm in cross section or Ø 860 mm)

10 EB CHR EB CHR features for cp Titanium and Grade 5 up to 8 EB guns up to kw EB power up to kg/h melt rate up to mm ingot lenght up to 30 mt ingot weight Up to mt/year

11 Scrap melting PA CHR Main application Ti alloys with stringent alloy variation requirements (Ti6 4 fastener) Ti alloys with high percentage of volatile elements No evaporation losses of volatile alloying elements Melting under process pressure close to atmosphere (e.g mbar abs.) Use of inert gas (normally Helium) as plasma gas (e.g. 100 sm³/h per torch) Recyling and Purification System for inertgas necessary (removal of H2,O2,N2 moisture, ) Melt rates limited/lower than EB because of lower efficiency Production cost higher than EB due to lower efficiency

12 PA CHR PA CHR feature For Titanium Alloys up to 6 plasma torches up to 10 MW plasma power up to kg/h melt rate Up to mm ingot length

13 Comparison table EB CHR/PA CHR Criterion EB CHR PA CHR Typical energy source EB gun ( kw) Helium plasma torch ( MW) Consumable parts Block cathode, filament Nozzle, rear electrode, gas ring Installed power range kw kw kw kw Typical melt rates kg/h kg/h Energy consumption kwh/kg Ti kwh/kg Ti Melting conditions High vacuum < 0,1 Pa Helium mbar abs. evaporation losses Medium high None Typical Ti grades All cp grades, Ti6 4, other Tialloys with low volatile content Ti6 4, all others except cp grades

14 Comparison table EB CHR/PA CHR Criterion EB CHR PA CHR Agglomerate material chips, cobbles, sheet, compacts Chips, cobbles, sheet, compacts Bulky feed stock size up to 700 x 700 mm up to 300 x 300 mm Energy distribution very flexible and superb (high frequency deflection system) Limited (mechanical movement of torch) Ingot surface qualtiy superb, independent on geometry good, depending on geometry Machining loss 2 3 mm 5 7 mm Casted geometry round ingots, slabs, double cast, Round ingots, slabs limited in size multi strand and other geometry Additional equipment none Helium recycling and purification

15 Conclusion Each cold hearth process has its pros and cons decision for the suitable process depends on application Key factor is Titanium material grade specification EB CHR focus on cp grades and Ti6 4 standard grade PA CHR for Ti6 4 with stringent alloy variation requirements and all other Ti alloys Overall production cost according TCO in EURO/kg Ti has to be evaluated to decide about competetiveness in the market place Maximizing scrap content minmizes cost of melting Processing scrap internally reduces cost of scrap significantly

16 ALD single source solution provider With ALD s international partners the complete scope in between the first business idea to the turn key melt shop can be covered Scope of possible services from feasibility studies to complete melt shop design concept proposals Production cost calculation and production cost optimization models [Euro/kg Ti] Concept studies and basic engineering of scrap processing lines Material weighing and blending units and compacting presses Consultancy for production of PQ material Project management services for furnaces or complete process lines or melt shops Installation supervision and commissioning or turn key installation

17 ALD single source solution provider Scope of possible hardware supply In house scrap processing lines and pre treatment lines Material weighing and blending units Compacting presses Cold hearth furnaces (EB CHR / PA CHR) with all peripheral equipment Helium recycling and purification systems for plasma furnace Vacuum Arc Remelting furnaces stub welder button melting furnaces

18 Your single source solution provider