OK so help me to understand the logic better.  This is where don't follow
the argument.  If 75% of silver today is a byproduct of mining other metals
why are the impacts being allocated as though it was the primary reason for
the mining and smelting. The silver is not being extracted from a silver
mine it is a zinc mine or a copper mine.  Isn't silver separated from the
copper during the electrowining of the copper?  In that case if we want the
copper the sulfate emissions from the silver will happen anyway.  The silver
is truly a byproduct.

If we get to the situation where lead, zinc, and copper ores are mined
primarily for the silver (the lead, zinc and copper being thrown away as
being worthless) then allocate all the impact to the silver.  I would agree
then that the impact from silver mining would be tremendous.

BTW from what I can tell eliminating the use of lead, even in car batteries,
will not stop the mining of lead.  Lead is found often with zinc and copper
ores. I suspect it would have to be separated and become mine waste.  I'm
not convinced either that eliminating lead is the best environmental choice.


Bill Hoffman

Motorola Advanced Technology Center
Environmental Technology Group

Phone: 847-576-7739
  FAX: 847-576-2111
Email: [log in to unmask]


-----Original Message-----
From: b_ellis [mailto:[log in to unmask]]
Sent: Monday, July 08, 2002 2:01 AM
To: Environmental Issues; Hoffman Bill-ARES56
Subject: Re: [EN] German doc on environmental cost of leadfree in
English


Bill

I must come back to you on this. Why does silver have more value than
the other metals commonly found in the same ore? Because it requires
treatment of large quantities of ore to extract a given weight of the
metal. The richest ores contain only about 0,085% of silver. The most
usual silver ores, argentite, stephanite, proustite and polybasite, are
all sulfides with admixtures of other metals and usually "diluted" with
iron pyrites, lead sulfide, copper sulfide, antimony sulfide and arsenic
sulfide. The extraction of silver is therefore accompanied by large
quantities of SO2 and/or H2S. There is one silver ore which is not a
sulfide, cerargyrite, a chloride sometimes accompanied by native silver.
This is richer but relatively rare.

In fact, only about 25% of the silver is extracted from the richer ores
(>0.05%) mined expressly for their silver. The other 75% comes as a
byproduct from lower grade ores which are extracted mainly for other
base metals, mostly lead and zinc, but also copper. If lead mining were
halted, as the ecopoliticians and activists may like, there would be
insufficient supply of silver and prices would rocket, but so would the
silver-related pollution because there would have to be more sulfur
compounds emitted, rather than the present concomitant pollution
engendered by the base metals, whose weight may be 20 - 50 times greater
per unit weight of ore.

The point is that silver is both expensive to extract and produces large
quantities of pollutants to do so. Whether the calculations are based on
value or sulfur emissions, the end result will probably be quite
similar, on condition that lead winning is continued.

Brian

Hoffman Bill-ARES56 wrote:
>
> I just want to point out that usually IKP/GaBi allocates the impact of
> mining by value not mass thus putting the vast majority of the burden for
> mining on valuable materials.  I suspect that this is true in this
analysis
> as well.  Notice that in most of the graphs the majority of the impacts
are
> due to silver, even though silver is around 3% by mass of the composition
of
> most solders.  I suspect the conclusions would be different if the
> allocation of impacts were by mass rather than the value of the materials
> being mined.  I'll leave it up to the group to debate which method of
> allocation most accurately assigns environmental impact of mining to an
> element.
>
> Bill Hoffman
>
> Motorola Advanced Technology Center
> Environmental Technology Group
>
> Phone: 847-576-7739
>   FAX: 847-576-2111
> Email: [log in to unmask]
>
> -----Original Message-----
> From: b_ellis [mailto:[log in to unmask]]
> Sent: Saturday, July 06, 2002 4:12 AM
> To: [log in to unmask]
> Subject: [EN] German doc on environmental cost of leadfree in English
>
> Hi,
>
> I'm coming back just to say that the University of Stuttgart
> presentation on the environmental cost of leadfree solders has been
> kindly translated by Peter Roth of Bosch and this has been approved by
> the original authors. (Thanks, Peter). I was overwhelmed by the number
> of members asking for the German version, so I shudder at the thought of
> having to do the same for the English version with my present
> disability. I have therefore placed the doc on the web at
> http://www.protonique.com/download/ where interested parties can
> download it freely (PDF file, 3.4 Mb). Please note that opening the file
> will produce a small hiccup about half way through. Just ignore it and
> carry on and it will continue normally.
>
> As I have had to re-subscribe, I'll lurk here to see reactions, but it
> is unlikely I'll post unless there is something that REALLY needs me!
>
> I should like to thank all who have enquired after me and apologise for
> not having replied. My problem makes it hard, but not impossible (as you
> can see), to respond. I'll give an update of the situation. On Monday,
> two weeks ago, I suffered a minor stroke which affected my RH side and
> especially my right hand which was totally paralysed. This hand, which
> behaved like a slab of wet fish, was useless for either keyboard or
> mouse control. I've been lucky and now have recovered 90% of movements
> (with conscious effort), 50% of strength (least in index finger and
> thumb) and 20% of agility, so I can now do most everyday things, albeit
> perhaps slowly. Computer use is still a big effort, though. Hopefully, I
> will improve further, with time and patience. I'm still undergoing tests
> (CT scan revealed minor ischaemic problems and other normal signs of
> aging: MRI scan not possible because of my pacemaker: blood chemistry is
> fine: will have carotid doppler and possibly angiogram tests next week).
> Preliminary Dx and prognosis is encouraging so you may have to put up
> with me for some time yet, even if not in the immediate future.
>
> I request no correspondence on personal matters, please!
>
> Good bedtime reading of the presentation!
>
> Best regards,
>
> Brian