Silver Reclamation
Tom Benedict
Are there any good pointers on how to reclaim silver from developing
chemicals? The recent thread on how to dispose of chemicals has made
me want to clean up my act a little.
Tom
Michael Langford
be reclaimed by placing it in a jug and adding a strip of aluminum foil
to it about 1x3 inches or so. When that strip dissolves then add another
and keep doing this until no more will dissolve. The sludge at the
bottom is what is refined for the silver. I'm trying my first jug now so
I'm not sure how well it works, but maybe this will help.
dvaustin
Michael wrote:
I recently read a thread here that said silver from used fixer can
>be reclaimed by placing it in a jug and adding a strip of aluminum foil
>to it about 1x3 inches or so. When that strip dissolves then add another
>and keep doing this until no more will dissolve. The sludge at the
>bottom is what is refined for the silver. I'm trying my first jug now so
>I'm not sure how well it works, but maybe this will help.
Has anyone tried this method? How long does it take for a gallon of fix,
or five gallons? Can the amount of foil be increased when doing larger
quantities? Are there any pointers that anyone might have on the prosses?
After turning the silver to sludge is the remaining liquid safe for drain
disposal? Where do you go to prosses the sludge? Is the cost of foil
greater then the profit from the silver? ETC?
Thanks
Dave
Marc F. Hult
Tom Benedict wrote:
>
> Are there any good pointers on how to reclaim silver from developing
> chemicals? The recent thread on how to dispose of chemicals has made
> me want to clean up my act a little.
>
> Tom
The following is my first pass at organizing information on silver
reclamation methods that might be of interest to other amateur photographers. I alluded
to this effort in several other threads in rec.photo.darkroom. If we can come up with
something sufficiently useful and authoritative, I'll summarize it for the proverbial
future FAQ and look for a suitable place to park it.
Corrections, additions, contributions, comments, suggestions, criticisms, clarifications,
guidance and encouragement are welcome. "My dog ate my newsreader so I haven't read the
rest of the thread but don't you know that 3M makes a silver-free film but it uses
animal products for the gelatin so I don't buy it but why don't you since its not
a problem anyway?" doesn't qualify as any of these ;-). Contributions that the solve
the problems they identify are especially appreciated. Inclusion of specific information and
experience with practical approaches to silver reclamation is crucial. The long-winded
introduction and structure is there to avoid having to deal with too many times with too
many "My dog ate.." issues. I've encorporated most comments in the ongoing "What do
you do with chemical waste" thread.
For me, this exercise is so I can go back into the darkroom more confident that I've
dealt in an responsible way with a potential environmental complication of my creation.
I also happen to like to do techie things .. else I'd feed C41 film to a point and shoot
and send the film to K-Mart. So if you want to help walk this particular puppy,
I'll be glad to share the leash -- even bring the baggy -- but if you need to take
the shortest route, please get your own dog.
Thanks ... Marc
DISCLAIMER: I have 25 years experience in research in hydrology and geochemistry
with emphasison the movement and fate of organic pollutants in the hydrologic environment.
I have spent the last three years teaching Environmental Geology, Water Resources,
and Hydrology. However, no employer is responsible in any way for, or has any
claim to, this document.
DRAFT 1.00 : Silver-recovery methods for amateur photographers Prepared 7-10-96 Marc F. Hult
PROBLEM:
Most film and paper used in amateur photography contains silver-bearing compounds.
Processing of this photosensitive material removes about 75% of the silver from
black and white images and essentially all the silver from color images. After processing,
the removed silver is contained in solutions that need to be disposed of in an
environmentally appropriate manner.
The solutions also contain other organic and inorganic compounds. Individual solutions
may be acidic or basic.. In small quantities, and if combined to approximate a neutral
pH, under many circumstances it is appropriate to dispose of these solutions along with
normal household liquid waste (after dilution) or solid waste (after absorption by a
suitable material). However, the silver in these solutions can act as a biocide that is
harmful to aquatic and micro-organisms if present in sufficiently high concentration. The
silver also tends to accumulate in the sludge produced by sewage treatment plants which
could marginally and incrementally increase the cost and complexity of disposal or
reclaimation of this by-product. Moreover, discharge to sewers of silver-laden solutions
is prohibited in some jurisdictions. Small waste-disposal systems such as septic tanks
that serve individual households may be susceptible to disruption by the discharge
of photographic wastes. World-wide, there are environments that, owing to geologic
and other factors, are particularly sensitive to degradation by trace metals.
Therefore it is desireable to reduce the silver concentration of darkroom effluent
before dilution and disposal. Resource recovery is an additional useful goal which is made
more economically practical by the fact that silver is itself a valuable commodity. Once
recovered, silver can be sold to offset the cost of its extraction from the waste stream.
Such extraction is routinely practiced by industrial and commercial processors. The methods
used, however, are generally not suited to the small volume of wastes intermittently produced
in a typical amateur's darkroom. In many areas, recycling and hazardous waste disposal centers are
available that accept household waste at nominal or no charge.
SCOPE:
This FAQ deals with the treatment of small volumes of typical waste produced by amateurs
engaged in processing of black and white film and paper. It does not address waste from
color methods [COMMENT?] which have more complex and variable chemistry. It does not deal
with other disposal or treatment alternatives such as off-site processing which in many
cases may be easier and more practical than on-site silver recovery. This FAQ is specifically
not intended for use in complying with regulations or laws governing waste disposal or
occupational or environmental safety and may not be cited or used for these purposes
[ COMMENT: The document may have to be copyrighted for this to stick. Any legal beagles?]
OBJECTIVE:
To identify and help implement practical procedures to recover silver from amateur black and white
photographic processes.
APPROACH: [This should be the guts of the FAQ, but its where I'll stop for now. MFH 7-10-96]
Silver can be removed from waste solutions by precipitation reactions, displacement by other metals,
electrochemical techniques, or ion-exchange methods.
Precipitation Reactions:
chemical agents -- sodium sulfide
non-selective compound -- sodium hydrosulfite
Metal Displacement:
by less noble metals, e.g., zinc, copper, iron, aluminum
Michael Langford <mi...@texas.net wrote in Re: What do you do with chemical wastes?
> TomTom, I recently read a thread here that said silver from used fixer can
be reclaimed by placing it in a jug and adding a strip of aluminum foil
to it about 1x3 inches or so. When that strip dissolves then add another
and keep doing this until no more will dissolve. The sludge at the
bottom is what is refined for the silver. I'm trying my first jug now so
I'm not sure how well it works, but maybe this will help.
bwe...@electron.rutgers.edu (Ben Weiner) wrote in Re: What do you do with chemical wastes?
:
BTW, I _think_ silver will plate out of used fixer onto steel wool.
Toss steel wool in the old fixer and leave it for a long while and you
should get plated wool and some sludge. (Someone correct me if I'm
wrong.) Of course, you have to decide what to do with the wool and
sludge, but even if you just put it in the garbage, at least it isn't
going directly into the water supply.
Electrochemical Techniques
Electrolysis
Galvanic
Ion-Exchange Methods:
DISCUSSION:
SELECTED REFERENCES:
Kodak publications:
"Safe Handling of Photographic Chemicals", Publication J-4
"Disposal and Treatment of Photographic Effluent, Publication J-55
" Disposing of Minilab Effluent" Publication J-20
" Disposal of Small Volumes of Photographic-Processing Solutions" Publication J-52
"Photolab Design" K-13
S.D. Shaw and Monona Rossol, 1991, "Overexposure. Health Hazards in Photography", Allworth Press, NY, NY,
320 p.
SUPPLIERS AND PRODUCTS:
Kodak Chemical recovery Cartridge Model II
(for use with at least 5 gal of fixer/week CAT # 173 4953 $65.25
Kodak Chemical recovery CartridgeJunior Model II
(for use with at least 3.5 gal of fixer/week CAT # 166 9431 $54.25
Kodak circulating Unit Model II (directs flow of solution from processor or holding tank to recovery
cartridge. Required for initial installation of above cartridges. CAT# 175 0868 $38.45
Kodak Silver Estimating Test papers Book of 200 test papers CAT# 196 5466 $18.50
Ion exchange products:
Environmental Products International (303)-824-3294
Electrolytic units:
CPAC Inc (800)-477-1417
Drew Resource Corp (201)-344-0201
Rotex Silver Recovery Corp (513)-322-0189
Siltech Corp (213)-371-5355