# Enzimes to recover silver from film?



## rickbb (Jul 22, 2013)

Anyone heard of this method actually being used?


RECOVERY OF SILVER FROM WASTE X-RAY FILM BY ALKALINE
PROTEASE FROM CONIDIOBOLUS CORONATUS

http://www.ku.edu.np/kuset/vol6_no1/7_Seeta.pdf


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## mda20 (Jul 24, 2013)

I think you may get answers in this link :
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=213

Regards
mda


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## rickbb (Jul 24, 2013)

Thanks, I've read that thread, but I was wondering if anyone had heard of using this enzime method instead of a heated lye solution.


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## NobleMetalWorks (Jul 25, 2013)

It's interesting it falls right in line with organic Aqua Regia, bacteria that has been found in Australia that seem to consume, and deposit gold, the bacteria in Iron Mountain Mine that break down sulfur and produce sulfuric acid as a by product that ends up dissolving heavy metals, and which has since been shut down due to water pollution and is now considered the largest EPA super fund in the US.

I find these subjects really interesting to read about, but when you start thinking about applying them in a way that would enable refiners to make them viable?

I don't think we are there yet, nor will be for a long time.

If this is only an interest, I am right there with you, I find very interesting. But if you are wanting to learn about this because you want to apply it as a viable recovery method, you might want to consider a few things.

The Enzimes will be more expensive than lye, and you have to provide just the right environment for them to work Consider this from the link you provided:



> Cultural conditions and production of enzyme
> The organism was routinely sub-cultured and maintained on MGYP (malt extract-3; glucose-10;
> yeast extract -3; peptone -5, all ingredients in g 1-1) agar slants and preserved between 15 to 28˚C.
> Enzyme production was carried out as described earlier in 500 ml Erlenmeyer flasks containing 100
> ...



So there are expenses involved in maintaining the cultures, these are consumables.

You are still using an alkaline solution:



> Alkaline protease from Conidiobolus
> coronatus was investigated for enzymatic hydrolysis of gelatin from waste X-ray films.



The only difference is that your Enzimes are responsible for it, not a lye mixture.

So since you are dealing with an alkaline anyway, and it seems to take so much effort in order to be able to make, and use the Enzimes, what would be the benefit over lye?

This reminds me of a post made on another forum I belong to, where the person posting was talking about "converting" lead/sulfuric batteries to lead/alum batteries. If you google it, it's all over youtube and the rest of the internet and being billed as a safe alternative to sulfuric acid/lead batteries. It's just simply not the case, what they are essentially doing is replacing the sulfuric acid with a weaker sulfuric acid made from alum, distilled water, and electrolysis. During the process they part the metals from the solution, and plate them out inside the battery basically leaving behind potassium and sulfuric acid. They really didn't do anything, and probably ended up spending more money in time, effort and energy than if they just bought a new battery or purchased battery acid and refilled it.

Many times what seems new, is just another way of producing the same thing with more labor, time and money. I would say just use the Lye, it's cheap and readily available and you more or less get the same exact results.

Scott


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## goldsilverpro (Jul 25, 2013)

rickbb said:


> Anyone heard of this method actually being used?
> 
> 
> RECOVERY OF SILVER FROM WASTE X-RAY FILM BY ALKALINE
> ...


This method was popular in the 80's. It was quite safe, was fairly fast, and did a good job. The problem was that it made the entire building smell like a sewage or rendering plant. Many companies tried it but most soon went back to caustic soda. I had a small 350 gallon tumbler setup for several months but couldn't stand the stink. Also, I don't think it will work on Dryview, which, today, is a common type of medical x-ray film and is often found mixed together with rare earth medical, which can be stripped with an enzyme.

Back then, the main companies selling the enzyme were Rohm and Haas (Rozyme P-64) and Miles Laboratories (Gelatinase No.3). The stuff was expensive. I also think Corning sold a variety of it. 

I've always wondered if Rid-X might work. Sure would be cheaper.

It's been a long time but I think I used the Miles Labs material. It was a liquid and it only took 400ml per day for the 350 gallons. The pH of the solution was 9.2 and this was obtained by adding baking soda (sodium bicarbonate) - I'm thinking it took 100-150 pounds of baking soda to make-up the 350 gallons. The solution operated at 50C (122F). I used the same solution over and over for the several months I had it.


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## rickbb (Jul 25, 2013)

Thanks, I find it an interesting read, and was wondering why it wasn't used over something dangerous like a hot lye.

I spent 20 years in the printing industry creating and then sending tons of litho film to be recycled, maybe some of it went in the organic batch.

I used to get about 10 to 20 lbs of flake a month out of my main electrolictic recovery unit. Those were the days, if only I had stockpiled that stuff. :lol:


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