Why do people put steel or lead washers into Coke cans?
Cans are bought by weight.
So the really big shonks put the steel or lead into some cans then squashed them and tossed them into a sack full of mixed crushed & uncrushed cans.
The government funded can recycling purchase price was nearly twice the actual scrap value so you could make a lot of money.
The do good charities were the worse offenders sad to say , I suppose they thought the new dialysis machine was worth the deception & I doubt they realized the potential fatal consequences of their actions.
The final attempt down here was to only accept uncrushed cans then run them over a magnet & down a spiral seperator to weed out the "funny " cans.
You also get rocks, gravel, all sorts of stuff to make them heavier.
However this was very slow, caused all sorts of arguements & fights and for the sellers was unprofitable as a 10 x 6 x 6 trailer load of crushed cans goes about $250 but the same volume of uncrushed cans goes about $ 60.
Cans are painted both sides and the paint can go 10% by weight but typically was 3-5%.
Being paint, it burns well before the Al melts and as it burns it takes some of the can with it.
We have all tossed a beer can in a fire and you don't end up with a plug of solid Aluminium sitting in the bottom of the fire.
SO they have to be plunged under the surface to avoid paint burning ( no air under the melt ) but when you do that any liquid trapped in the can explodes ( steam explosion ) so in reality can recycling is a money loosing exercise.
Steel cans suffer a similar fate.
Because of the solder they can only be used in malleable iron casting and because adding carbon to steel to revert it to cast iron is very difficult you can only add a small amount which you balance by adding pig iron.
And you still can end up with the solder seperating with the tin going into solution and the lead dropping to the bottom of the furnace.
The "no tin" solders are even worse so regardless of what you read or hear most steel cans go to the tip .
When they were made with tin plate you could recover the tin with a caustic bath.
the detinned cans are then left out rust to nothing, the rust is then ground and magnetically seperated then pelletised and sent to blast furnaces.
The seams with solder in them get burned then used in fertilizer.
However now 3/4 of the cans are zincalume coated with renders them totally unable to be recycled and even worse the zinc coating has a very short shelf life which sort of defeats the purpose of canning in the first place.
No more now, I can feel Musky's breath over my shoulder. finger poised on the delete button.