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[GreenYes] Re: Green Darkroom Parties (was [P2] Green cleaning parties)

I learned about extracting silver from films while watching Eco Tech on Discovery Channel.  I have been researching the methods to extract silver from:

1) films
2) negatives
3) photo processing wastes

...and here they are:

1) Electrolysis
2) Ion Exchange
3) Metallic Replacement
4) Precipitation

To find out the cost, the advantages and disadvantages of each process, take time to read "Photographic Processing Waste Management" by Environmental Health and Safety (EHS) and EPA.

I read on Finishing that a student, Obogheneruru Orhuesie, used the electrolytic method of recovering silver for almost a year. He managed to fund his education, in a renowned university in Nigeria, from the proceeds he received from the sales of the recovered silver.

Juan M. Arcos has this recovery method to share. He heats oxalic acid of 5% concentration to 100 degree Celsius, put the film into the acid for 20 minutes and all the silver will drop to the bottom. He said that there is no fumes, risk or environmental damage, just pure silver with this method

According to a write up on "Clean technology for the recovery of silver from processed radiographic films" by Science Direct, boiling films in oxalic acid separate the inorganic component from the polymer substrate. Recovery of silver is achieved by melting and the process recovers good quality silver and offers a very high yield.

If Mr Mohd is aware of this, would he still consider making "kompang" out of X-ray films?

Please add to my list if you have more methods up your sleeves. 


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