Method for recovering silver from photo chemicals

[Juan Manuel Arcos Frank]

Hi Matt.

Well,it depends on the way you get spent fixer.If you get it for free then go ahead,you will have fun recovering that little amount of silver.

If you are buying it then you must keep your eyes open for making money.Low silver concentration is not a good bussines except you buy spent fixer very cheap.

All precipitation processes work pretty good with low silver concentrations.

Kindest regards

Manuel

 

[Auful]

Hi Matt.

Well,it depends on the way you get spent fixer.If you get it for free then go ahead,you will have fun recovering that little amount of silver.

If you are buying it then you must keep your eyes open for making money.Low silver concentration is not a good bussines except you buy spent fixer very cheap.

All precipitation processes work pretty good with low silver concentrations.

Kindest regards

Manuel

Manuel,

Thank you very much. I am getting it for free, so my overhead is rather low; just the cost of zinc and a bit of time. I precipitated out silver, with zinc, from 250 mL of the fixer on hand. Once washed and clean, I plan to get an estimate, from this sample, of the actual silver concentration in this fixer. Why not use iron/steel powder instead of zinc? I'm exploring ways to make disposal easier and safer, without having to precipitate the zinc later with iron.
Matt

 

[upcyclist]

I am getting it for free, so my overhead is rather low; just the cost of zinc and a bit of time. I precipitated out silver, with zinc, from 250 mL of the fixer on hand. Once washed and clean, I plan to get an estimate, from this sample, of the actual silver concentration in this fixer.

(my emphasis)

Don't forget your waste disposal time & materials. Scrap iron (or non-stainless steel) can be had for free, but you'll probably be buying something to neutralize your post-precipitation spent acid, assuming you refine what you drop. Consumable lab supplies also include things like filters & pH paper. Eventually, you'll need to figure out how much time & money it costs you to recover from a given concentration of spent fixer.

I'm basically in the same boat--starting this out as a hobby. So if I'm mildly in the red, it's just the cost of entertainment. But I have an eye towards making this a side income source, too, so I want to start tracking costs. Some of our costs will come down over time, both in fixed startup costs (facilities, glassware) and efficiencies (getting an electronic pH meter, probably an ORP meter too, being more accurate and conservative with acid use, better sources for materials).

 

[Auful]

Don't forget your waste disposal time & materials. Scrap iron (or non-stainless steel) can be had for free, but you'll probably be buying something to neutralize your post-precipitation spent acid, assuming you refine what you drop. Consumable lab supplies also include things like filters & pH paper. Eventually, you'll need to figure out how much time & money it costs you to recover from a given concentration of spent fixer.

I agree entirely. I will never be professional at this. I look at refining as a hobby; a means to enjoy learning chemistry, etc while converting some virtually worthless paper currency and coins (that,for some reason currently have a greater perceived value than their melt value), to substances with time-tested value. I do consider this a risky hobby with many dangers, as well, so I do not disregard safety or cut corners. No hobby is worth diminished health or death.

Back to the topic at hand: I am wondering why iron or steel powder could not be used instead of zinc to precipitate metallic silver from the fixer. Does it increase sulfide production, or is there some other undesirable side-effect I am missing?? "Steel Wool" (some form of iron) is used in the silver fixer recovery canisters, which minimizes toxins going in the drain. I know, first hand however, many silver and iron sulfides result from this process. If steel/iron could be used, would it not eliminate a step relating to disposal?

 

[upcyclist]

Back to the topic at hand: I am wondering why iron or steel powder could not be used instead of zinc to precipitate metallic silver from the fixer.

Please don't take my word on this (no direct experience), but I would think the primary difference is that zinc is more reactive than iron, thus your process would go quicker. When I'm dropping from cyanide plating solutions I'm using zinc dust, then processing the precipitant to ditch the zinc, nickel, etc.

Many folks use two cementation stages in their waste processing, as described by 4metals: with copper to drop PMs, with iron to drop most base metals, followed by pH manipulation to drop the rest. If you are only after silver, then you can probably use any metal that is more reactive. Since zinc is more reactive than iron, it won't drop out until you neutralize your waste solution.

 

[butcher]

We may choose a metal to use to cement values from solution for many different reasons, like how well the metal used is dissolved or washed from the cemented metal, or like in the case of iron and silver where the iron will not alloy with silver in a melt...