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From: Terje Mathisen <terje.mathisen@tmsw.no>
Newsgroups: comp.arch
Subject: Re: the power of junk, Is Parallel Programming Hard, And, If So, What
 Can You Do About It?
Date: Mon, 26 May 2025 22:09:44 +0200
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BGB wrote:
> On 5/24/2025 4:45 PM, Michael S wrote:
>> On Sat, 24 May 2025 20:36:50 -0000 (UTC)
>> John Levine <johnl@taugh.com> wrote:
>>
>>> According to BGB=C2=A0 <cr88192@gmail.com>:
>>>>> Don't forget to factor in energy costs.=C2=A0 The energy costs
>>>>> to refine and produce virgin aluminum are very high, relative
>>>>> to the costs of recycling aluminum.
>>>>
>>>> Granted, but possibly depends on the relative cost of energy.
>>>>
>>>> But, likely, as more total aluminum is produced the relative cost of=

>>>> aluminum would go gown. While recycling aluminum makes sense, it
>>>> does come with the tradeoff that recycling aluminum reduces the
>>>> relative cost of aluminum (and thus the value of producing new
>>>> aluminum would go down), so is less likely to be favored by the
>>>> primary producers (where a relative scarcity is better for profit
>>>> margins, ...).
>>>
>>> Aluminum is produced from bauxite which is around 40% aluminum and
>>> needs a multi-step energy intensive process to turn into metallic
>>> aluminum.=C2=A0 But aluminum scrap is already metallic aluminum.=C2=A0=
 My
>>> impression is that we are about as far down the experience curve as
>>> we are likely to get, and using scrap as a source will always be far
>>> cheaper than bauxite.
>>>
>>
>> Aluminum from bauxite is almost pure aluminum. Aluminum from scrap
>> contains significant and unpredictable amounts of magnesium, copper an=
d
>> silicon. Removing them is hard, in case of copper very hard.
>>
>=20
> Possibly why aluminum cans are "more favorable" for recycling, as the=20
> alloy the cans are made of is pretty much pure aluminum.

The can itself (bottom plus cylinder side) is quite pure Al, but the lid =

is an alloy with enough Mg added to make an impact on worldwide=20
magnesium consumption.

For remelting you would preferably have a way to separate the lids from=20
the rest of the cans.

Terje

--=20
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"