Malcolm
Yes, I agree with you that it is theoretically possible to purify
recycled solder back to Grade A levels, and that to extract tin from
cassiterite requires purification to remove some other metals. However,
it would seem economically more difficult to do so, in view of the great
mix of different impurities (metals and non-metals) in recovered solder,
compared with the few in ore. Also, the major solder producers have
extolled the virtues of virgin-grade solder for so many years that users
will take a long time before they accept recycled solder which has
traditionally been considered as OK for plumbers but not for us.
Brian
Alco-Met wrote:
>
> Brian Ellis wrote :
>
> >
> > I agree that recycling would be the ideal, but I wonder to what extent
> > the electronics industry would accept non-virgin grade solder,
> > especially as requirements for fine-line SMD work can be very critical?
> > I don't believe this problem would arise with most other applications
> > for solder, representing about 50% of the consumption, but I do believe
> > that we shall always require Grade A solder, hence mostly from freshly
> > smelted tin. (Solders and Soldering, Manko, p. 46)
>
> Since I applaud Brians efforts to discuss lead free issues rationally, I
> would like to clear up a commonly held metallurgical misconception that the
> above text implies ( whilst declaring in advance my interest as being a
> supplier of solder ).
>
> Following smelting ( the process by which metal oxides are reduced to
> metal ) there is invariably need for the smelter to refine its metal output
> to produce the Grade A or fresh (sic) tin.
>
> Such refining process ( usually electro refining or pyro metallurgical
> techniques ) can also be undertaken by recyclers so that the resulting
> solder has contaminant levels which meet or indeed exceed those which can be
> achieved using Grade A tin.
>
> So, subject to the laws of economics, the entire tin lead requirement of the
> electronics industry could be met from recycled sources.
>
> Perhaps this would be a more worthwhile development if we are truly
> interested in "joined up" environmental protection.
>
> Malcolm Noble
> Alco-Met (Solders) Ltd
>
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