Coke cans?

[ChristiaanJ]

This is meant as a serious "tech" question from an ancient engineer, but if a mod sees it needs moving, so be it.

Over the years, watching tired and ancient airframes being reduced to shreds (and yes, sometimes with a lump in one's throat):
What happens to the scrap?

- A lot of it is some variety of aluminium alloy, but it must be full of other "stuff", like fasteners, fuel lines, hydraulic lines, wiring, seals, plastic, etc.

- But, things like Coke cans and tooth paste tubes are extruded from nearly pure aluminium.

- AU2GN (RR58) as used on Concorde, and I suspect most modern aircraft construction alloys as well, are anything but pure aluminium.

So my question is...

Is a certain amount of alloy recoverable for re-use as base material for manufacturing aviation-grade alloy ingots, or is it all just melted down and separated, and only the aluminium as such is used (with maybe some of the other constituents skimmed off and re-used) ?

CJ

[colsie]

Anything of value is melted down and sold on by the company who 'trash' the aircraft. Key fluids are recycled. I believe airlines have a recycling method as well for maintenance aka anything which is expensive to buy, but can be reused will be given back to them for use in the future.

The alloys etc are sold onto whoever needs it. There are many rare metals in modern aircraft that are put to use in the making and maintenance of craft.

This is my limited knowledge.

[Dani]

Not being an engineer, I read a few articles (not written by engineers) that said that reclycled aluminium goes into articles of less quality, i.e. it goes from aircraft, then scrapped, then to cans, or consumer products or wires aso.

If my memory is correct, I lately read that you can use now reclycled aluminium also for aircraft again. I guess because of sophisticated melting technology, allowing higher metal purity. Maybe they mix new and old alu together.

Dani

[BYALPHAINDIA]

A 737 turned into Tesco tins.:=:ugh:

[Donkey497]

Just how much and how quickly the aluminium gets back in the sky depends on a few things.

Fairly large parts from aircraft which have very distinct alloy usages in distinct parts of the airframe are easily sorted at the break down stage so these can be meletd & recycled into a new batch of their given alloy as soon as there is a melt of that grade.

What helps is this instance as well is that most parts are designed to have a serial number always visible on them, which makes tracing the alloy grade dead easy. What doesn't help is when the tear down splits parts into two or more pieces.

When the parts aren't easily identified as any given alloy, then it's into the general melt. If the foundry is a specialist producer of aviation grade alloys, then they'll melt a batch of material to see which grade the resulting mix is closest to and then add either more scrap where the grade is known, or they'll add relatively pure ingredients into the melt to bring the overall balance of chemical elements into the ranges for each one within the alloy grade, or to bring the alloy mix into the range for a specific grade if they have an oder for that grade.

If they don't have a specific need then they'll often melt the scrap into batches and take an analysis of each one before casting it into ingots. In that way they can put material into stock, knowing then just what they need to add into the mix to take each "stock-melt" into a given alloy.

This doesn't just happen with aluminium, or aluminum to our US colleagues, but with the vast majority of metals currently in service. Sometimes of course, it actually takes an addition of a compound maybe limestone and maybe oxygen blown through to remove undesirable elements from a melted alloy to meet the specified limits.

Metal recycling is nothing new - I recall from my college days our metallurgy lecturer telling us that most modern steel has been recycled between 5 and 10 times and that aluminium was fast catching up, despite the increasing exploitation of reserves and increasing volume of these materials being produced annually.

Hope this helps.

[llondel]

There's a huge energy cost to producing new aluminium from ore, so it's almost always cheaper to recycle what's already been extracted.

[ChristiaanJ]

Just how much and how quickly the aluminium gets back in the sky depends on a few things.....Many thanks!
The rest of your post answered exactly all I was asking!

Apart from anything else, that is a nice thing about PPRUNe. Ask a question, and you promptly get an answer!

As to the Coke and Tesco and Tennant cans.... and alu toothpaste tubes (do they still exist?) they're extruded from near-pure alu pellets. Too much other metals in there ruin the extrusion process (my Dad worked in that business, which, I admit, partially triggered my question :) ).

So, among other things, from what Donkey497 explained...
Not that much of F-BVFD (the one Concorde that was scrapped) ended up as Stella beer cans. Some of it even may still be flying around somewhere. Pleasing thought somehow.

CJ

[colsie]

May i then ask what occurs with the composite aircraft when and if they are retired?

[ChristiaanJ]

May i then ask what occurs with the composite aircraft when and if they are retired?Now that my question has been answered, it may be worth tackling your question right here!

You certainly can't turn them into beercans, or even into base material for new aircraft.

They may turn out to be the same kind of albatrosses as the "hybrid" cars, seemingly a good idea, but overall more of a problem to manufacture, and far more of a problem to dispose of.

CJ

[Bolty McBolt]

Have heard but can't confirm the recycled alloy from aircraft is hight prized as the metal to make alloy engine blocks ....:ok:

[411A]

Have heard but can't confirm the recycled alloy from aircraft is hight prized as the metal to make alloy engine blocks ....

And the titanium from some aircraft (L1011, for example)....tear strips, and certain forgings.

[Dani]

colsie:
May i then ask what occurs with the composite aircraft when and if they are retired?

There is no difference: reusable materials are recycled, others are destroyed (incinerated).

This is nothing new, since already todays aircraft have considerable percentages of non-reusable materials. Think about the seat tissue, the cabine covers, but also heavy structurs like the vertical stabilizer of an A300 (of which the first ones are slowly being retired) are non-reusable (stabilizer: composite material).

You also have to forget the notion that composite aircraft are made of fibers/resin only. Modern heavy duty composites like on the 787 partly consist of light weight metals. They first have to be extracted from the composite and can then be recycled.

Dani

[john_tullamarine]

This is meant as a serious "tech" question from an ancient engineer

(a) I have an affinity with that class of folk who might be described as ancient engineers .. (olde pharts between ourselves ....)

(b) it doesn't have to be terribly related to flying to be OK for tech log .. main thing is it needs to be of interest to (at least some of) the assembled folk ...

(c) my favourite not terribly related to flying thread (http://www.pprune.org/forums/tech-log/10543-morse-code-can-anyone-help-2.html) had to do with Chinese cryptography ... I guess that we could figure out some relevance to flying over an ale ... perhaps ... and I figure that's enough justification to leave it run ....

... I thought that the thread was fascinating .... it really is amazing what one can learn from the incredibly catholic wealth of knowledge represented by the assembled PPRuNe fraternity ...

(d) coke cans ? .. some pilots drink Coke ... close enough for me ...

[ChristiaanJ]

Thanks, John !
This olde phart hails from the days when glueing, and chemical and numerically controlled milling for large structural parts, were still relatively new techniques....

Have heard that recycled alloy from aircraft is highly prized as the metal to make alloy engine blocks ...Quite likely, although I would have thought the first source would be... old engine blocks ! Easier to strip of extraneous bits and pieces, and already pretty much the right composition.

Modern heavy duty composites like on the 787 partly consist of light weight metals. They first have to be extracted from the composite and can then be recycled.Are those a part of the composite itself (as in fibers, strands, mats, etc.) ? Or are they structural items embedded in or attached to the composite (such as, e.g., hinges) ?

[Dani]

as I said, I'm no specialist. The only thing I know is from aviation magazines and the aircraft I made conversion training on.

As I remember, composite structures are made in layers. Depending on the technology, the use and the strenght, they include metals like Aluminium, Magnesium and Titanium. Or any blend of it.

I also remember in an old Mirage III where the honeycomb structure was made of metals, i.e. the comb itself was made of very thin metal sheets.

On the 787 you have additional technologies: Bolts, hinges and any sort of conections are put into the resin structures. On the A350 they want to have similar sandwich structures, but with more metals in it. I can imagine that they will just include more layers of metal instead of kevlar/fibreglass/other fibres. They are mainly talking about Magnesium, but so far design is not yet freezed.

If you want to know more, try Wikipedia, e.g. under "Glare" ("GLAss-REinforced" Fibre Metal Laminate).

[ChristiaanJ]

Thanks, Dani !

Metal-metal honeycomb is not really a "composite", and it's well over 40 years old.
The Mirage III you mentioned is an example, so are aircraft floors on too many aircraft to list, so are the Concorde elevons and rudders, and the nozzle/reverser buckets.

[TeachMe]

Perhaps someone could answer this little tag question. Why is it that many ships (my dad's old ship HMCS McKennzie as example) and even old NY subway trains are sunk as artificial reefs instead of being melted down? I know they are mostly iron, not much more expensive Al, but still would think they would be cut up and melted before being sunk.

[Donkey497]

As to why your dad's old ship & new york sub way cars are being sunk rather than recycled. there's a few considerations, some green, some not so.

Considering your old man's ship first. If it had been a comercial cargo carrier the odds are that it would have been run up a beach in India or Pakistan years ago & would have been scrapped, cut up and recycled that way. As it was a warship "of a certain age" its a bit more murky. The odds are that in its construction specialist (military) steel grades (specifically armour plate) were used in specific parts of its construction. Even although that happened 50 years ago there are still probably some alloying secrets which would be revealed by normal scrapping & that may still be prevented by either government edict or by a commercial contract.

FYI - Modern warships are pretty woossy in comparison to historical warships. WWII design vintage frigates, cruisers & battleships used high strength steel plates up to and heavier than 12" or 300mm thick. Modern ships do use high strength steels, but they are not generally armour plate and are nowhere near as thick. If you get a chance, compare the view along the waterline of say the USS Iowa (WWII Battleship) with say HMS Illustrious (1970's designed Through-Deck Cruiser/ very Light Carrier). On a sunny day, the battleship has a nice smooth waterline look, but on the newer boat, you can see every frame and rib stand out as a high point along the waterline in the reflected light. All this is because the plates used in modern ships are so much thinner (& hence more flexible) than was used even recently.

Secondly, even altough the ship was decommissioned over 10 years ago, the actual layout of the ship may reveal operational specifications of current naval equipment which may be undesirable to give away, on the open market, if the ship were offered for commercial scrapping.

Thirdly, by the time sensitive equipment, ancillary parts and cabling is removed, it may actually be uneconomical to a commercial scrapper to take the ship on as the material that remains may not be economically viable to cut up & recycle.

Similarly with the new york sub way cars, once the motors, cabling & mandatory or easily recycled stuff comes off it might not be economic to recycle the rest.

However, using these redundant vehicles for the creation of artificial reefs has distinct attractions:-
Where there are reefs, fish are able to breed and multiply hence improving commercial and recreational fisheries.
Where there are shallow accessible reefs in diving areas, dive tourism increases.
Where the artificial reefs are composed of semi-familiar objects used in unfamiliar arrangements such as the sub way cars, this has a secondary boost to the dive tourism. There are people sad enough to don rubber head to toe, strap air tanks to their back and spend hours in cold seawater, just to get one of their freinds to take a photgraph of them sitting ina subway car looking as if they are reading a paper. If this opinion offends some, tough, it's actually a quote from my cousin who used to run a dive shool in the Caymans.
Establishing an artificial reef also has benefits in land reclamation as it establishes an offshore hard edge to mitigate erosion of material between the reef and the existing shore.
Finally, an offshore reef has a dramatic effect in reducing the effects of offshore storms on beach front areas, which especially along parts of the US atlantic coast and Gulf of Mexico is a serious concern.

Hope this helps.

[ChristiaanJ]

TeachMe,
I may be wrong, but I thing often the main reason is the amount of asbestos in those old ships and subway cars.
That makes dismantling them such a hazardous, hence expensive, undertaking, that it's no longer economical.

Underwater the asbestos in its various forms becomes just a wet cakey mess that does not really disperse in the environment.

CJ

Edit:
Donkey497 got ahead of me, and also gives some perfectly valid reasons, IMHO.
Asbestos is an issue though: you should read up on the saga of the French aircraft carrier Clémenceau....

[ChristiaanJ]

And after Dani's post about recycling composites..... a thought....

How soon before we will see nearly-all-composite aircraft, such as the Boeing 797 and Airbus A390, being added to those artificial reefs?
After stripping out ... what? engines, electronics, landing gear, some pumps and generators and flying control actuators, burning the rest is hardly worth the trouble and the pollution and the landfill residue you end up with.

Oh, and what about a photo in seat 4B, with an FA bending over you... "coffee, tea, or me?" all in scuba gear?
Priceless, as they say.

[Capt. Slack]

Donkey: "Secondly, even altough the ship was decommissioned over 10 years ago, the actual layout of the ship may reveal operational specifications of current naval equipment which may be undesirable to give away, on the open market, if the ship were offered for commercial scrapping.:

What are you saying then... that divers are too stupid to understand the secrets of ships? :oh: (grin)

[ion_berkley]

Here's one of link (of many potential ones I'm sure) that indicates there is a future in recycling aerospace style composite materials. http://http://www.letsrecycle.com/info/waste_management/news.jsp?story=5554 (http://http//www.letsrecycle.com/info/waste_management/news.jsp?story=5554)

I've been seeing increasing articles on the subject recently, and it looks increasingly hopeful that these types of materials can be constructively recycled, though it seems unlikely that the resultant materials will be of the same grade.

[Donkey497]

No Cap'n, just that even in Canada, there's only a finite amount of space to store used military hardware while it goes fully obsolete. If you dump it underwater, it frees up room on land & makes it pretty damned awkward, but not impossible to do the type of snooping I alluded to in my earlier post. What it does virtually eliminate is the possibility of the opposition, or potential opposition buying up select parts, or whole sections of your former naval pride at scrap value on the open market.:eek:

Folks could still remove those self same sections from your pride & joy, but being on the ocean floor, even in relatively shallow water complicates this procedure enormously & makes it helluva noticeable.....;);)

A more subtle point on the metallurgy side is that even in solid metal, components can preferentially leach out of the metal & into solution, and potentially more importantly, vice versa, especially where salt solutions are concerned. So the longer that an alloy has been immersed in sea water, the more uncertain you are about what may or may not be a trace alloying element which adds to the confusion of anyone who salvages a sample of metal from, shall we say "an area of interest to them".


.....and ChristiaanJ, "Oh, and what about a photo in seat 4B, with an FA bending over you... "coffee, tea, or me?" all in scuba gear?
Priceless, as they say. " Oh Dear, Oh Dear, Oh Dear........

[ChristiaanJ]

.....and ChristiaanJ, "Oh, and what about a photo in seat 4B, with an FA bending over you... "coffee, tea, or me?" all in scuba gear? Priceless, as they say. "
Oh Dear, Oh Dear, Oh Dear........Well... it was yourThere are people sad enough to don rubber head to toe, strap air tanks to their back and spend hours in cold seawater, just to get one of their freinds to take a photgraph of them sitting in a subway car looking as if they are reading a paper.that triggered that one :)

CJ

[TeachMe]

Thank you all for the great replies!:ok:

I am not so sure i can see the security side of this in that over the 30 years of the ship's life 10 000 or more people have worked on, lived on, or visited the ship, so the layout itself is most likly 'known'. On the other hand, being able to take a sample of the alloy might provide some reason for this. Yet that would not expain the subway cars. Thus based on the subway cars, i would suggest it is more practicale/ecconomic than security.

Also, as these things are usually sold for 1$ I would guess it is a headache to get rid of them, and thus is ecconomic. The enviromental benefits are of course very good, but lets face it, very few organizations and governments do enviromentally favourable things without there being an overall beneift to themselves.

Thinking of the point of being in salt water and leaching, while I can see that as reasonable, would there not be a lot more uncertainty in the ore dug up than the ship cut up, thus negating that reason? (not disbelieving, just trying to understand :) )

Just did a bit of research and found that steel prices are about $900 a ton, and the MecKenzie was about 2900 tons. So at a very rough guess the steel to build it would cost over 2.5 million dollers. (I know I know, very rough numbers)

I must admit I still find it surprising that it is not ecconomical to recycle it instead of sink it as I sould expect (wrongly it seems) that someone would be willing to pay at least a million for it. Yet even more surprised at how cheap steel is!

All I can see is that it must come down to aspects such as asbestos contamination that make it actually hard to cut up safely, even in India.

No need to worry about offending re comment about scuba divers sitting in train cars having their photo taken, I rather think that is daft too, but perhaps not as much as standing at the end of a runway on a cold damp day to take photos of planes landing..... :hmm:

Now, as this is an airline forum, I shall redirect it back to that by reitterating the point made above about 787s and such planes becoing artifical reefs when thier life span if over.

Once again, thank you all for your good and informative replies,

TeachMe

[Dani]

ChristiaanJ, your idea about sinking composite is not a bad one. But burning is one of the most environmental-friendly way to get rid of non decomposing materials. We here in Switzerland, famous for maybe the most rigid ecological rules, are incinerating nearly all the rubbish - except the recycled one (glas return ratio: nearly 100%!).

The problem with burning is that you have to do it in a controlled fashion, i.e. very high temperature, in a plant, controlled, and exhausts filtered.

Dani

[john_tullamarine]

I must admit I still find it surprising that it is not ecconomical to recycle it instead of sink it

.. a minor consideration is that sinking often is effected by the military .. the bombers or submariners gain some degree of training value in the exercise.

[Donkey497]

On the 787 end of life subject, I doubt very much that they'll end up as an artifical reef or scuba diver's plaything once they come to the end of their life for a couple of reasons.

Firstly the surface of fully cured, "as molded" composites tend to have a very teflon-like quality in that it is very difficult for something to attach itself to the surface, such as plankton or other coral forming organism, unless the surface has been abraded to promote adhesion.

Secondly, the resins used in the composite manufacture are fairly to extremely toxic in their unreacted form. They tend to have relatively low vapour pressure, but can be resily soluble in water, so the chance that any might get into the marine environment over the long term is probably higher than might get into the passenger environment over their working life. Also, composites can be permeable to water, allowing unreacted monomer to be washed out of the solid structure over the long term.

Looking at what happened to an RAF Harrier a couple of years ago which crashed in the UK, a signiifcant amount of composite materials were damaged in the crash & contaminated a large area. I understand that the affected area was scraped clean of topsoil to a depth of a couple of inches and this resulting material was thereafter incinerated at high temperature to remove all traces of carbon fibre and resin particles. The remaining material was then analysed and declared safe once no composite material was found. I understand from a freind who worked for BAE on composite structures at the time that the incinerated material was eventually mixed with organic matter & finally used to fill a flowerbed at the RAF base used to recover the wreckage.