What is it?

[rickbb]

Probably another of my dumb questions, but.

I started with a iron exchange cartridge from an x-ray film processer, this is my 3rd from the same source.

I cut open the plastic housing, dumped it in a plastic bucket and rinsed all the black sludge off, cut open the steel mesh wrapper length wise down to the core and rinsed all the layers keeping the black sludge in the bucket and disposed of the screen mesh.

So far so good.

Let the sludge setting, siphoned off the excess water and added cold dilute sulfuric acid (30%), to dissolve any remaining iron. Let that work for several days, stirring several times a day. Siphon off the liquid and started the washing, after 3 or 4 washes I noticed an rusty iron scale floating on top of the water. So I repeated the sulfuric soak, washing until the water was clear. Took a 1/2 teaspoon of the washed black powder and melted in a melting dish, not silver, made a black glass like mess in the dish.

Hmmm I thought, I put it in HCL, got a reaction, lots of yellowish/orange color in the liquid. Washed it 3 times, water was clear. Repeated the HCL, this time on heat, yellow color, not as dark this time. Washed it until water ran clean and clear. Melted sample of the now gray not black powder, same black goo in the dish, not silver.

So, darn it, I put it in dilute nitric (30%), added low heat, (it's cold in the shop now), reaction, liquid is dark amber. The powder is now a light gray color, a drop or two of HCL in the amber nitric liquid shows no reaction at all, no white cloudy deposit.

So the question, what is this pound of now light gray powder I have? And where the heck did the silver go?

 

[Lino1406]

Describe where/how did the iron cartridge start?

 

[rickbb]

The cartridge was pulled from the fixer waste discharge from an x-ray film processer. It's an iron screen wrapped, "steel wool" type of ion exchange cartridge that uses iron to displace silver from the fixer effluent before sewer discharge.

I emptied the contents in a 5 gallon bucket, cut open the steel screen and rinsed with tap water. Threw out the steel/iron screen remnants.

Then began processing the sludge rinsed from the steel mesh, which should have been mostly silver with some partially dissolved iron mixed in. Started with a dilute cold sulfuric acid which should have left the sliver alone and put the iron in solution.

 

[butcher]

I do not understand why you would try to put the silver back into solution with acids, or even try to dissolve the iron or iron compounds with acids from the silver.

You will most likely have iron oxides involved which will not be dissolved easily, if at all, in acids.

The silver has been reduced to metal, silver will not form an alloy with iron in a melt, after removing most of the elemental iron mechanically I would try to flux and melt the silver with iron oxides collecting in the slag.

Note: I have not worked with any of these (MRC) metallic replacement cartridges, used to recover silver from photographic waste, so another member would be better to get advice from on this subject.

 

[kurtak]

I started with a iron exchange cartridge from an x-ray film processer,

I cut open the plastic housing, dumped it in a plastic bucket and rinsed all the black sludge off, cut open the steel mesh wrapper length wise down to the core and rinsed all the layers keeping the black sludge in the bucket and disposed of the screen mesh.

rickbb

you need to "smelt" (not just melt) silver that has been recovered such as this from fixer solutions --- the reason for this is that not all of the recovered silver is reduced to elemental silver - some of it is recovered as silver sulfide (the black sludge as underlined in the above quote)

These iron exchange cartridges work on the principal of cementing the silver out of solution & what happens is at first when there is lots of iron (steel wool) in the cartridge for the solution to contact more of the silver (in solution) is reduced to its elemental state - however towards the end of the cementing process most of the iron has gone into solution so there is less iron available to complete the silver reduction (to elemental silver) thereby leaving you with the black sludge which is silver sulfide

In order to complete the conversion of the silver sulfide you need to "smelt" it with a flux made up of borax & soda ash along with some iron in the crucible (nails or rebar) the sulfur in the silver sulfide reacts with the iron to complete the conversion to elemental silver & then the dissolved iron reports in the flux/slag

You need a gas fired furnace & a cone mold for the smelting process (you can make a make shift cone mold out of angle iron)

I have never actually done silver recovered from the type canister you are working with - however I have done many pounds of silver recovered from fixer with the electrolytic rotating drum recovery systems & I believe principal is the same - meaning the recovered material is the same (recovered silver plus silver sulfide)

GSP, Harold or Juan Manuel Arcos can/will correct me if I am wrong - but I believe the results (silver plus silver sulfide) are the same whether the silver is recovered from the fixer with the steel wool canister or with the electrolytic rotating drum

Here is a link to the first time I worked with fixer recovered silver where GSP, Harold & Manuel got me headed in the right direction http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=12404 --- this first batch I did was something like 22 pounds & I have done many more pounds for the guy I got it from since

Kurt

 

[kurtak]

Thought maybe I should ad these pics showing set up you need for smelting - the silver on the scale was a small batch of fixer recovered silver/silver sulfide

the cone mold is on the ground to the right - I put it on the turkey fryer burner to heat it before pouring metal/slag into it - in this picture I had the crucible sitting on the turkey fryer burn to preheat it & drive any moisture out before putting it in the furnace

the cooking oil on the table is used to create the carbon layer in the cone mold - & you can see the rebar on the table used in the crucible for the smelt

Kurt

 

[rickbb]

It's probably me, I have recovered 2 of these before and put the mud from the initial rinses in HCL which dissolved most of the iron, then smelted with 1/3 soda ash by weight with a dash of borax.

That yielded some nice silver but since, a. I'm still lousy at smelting/melting and b. only have melting dishes to work with I had read some posts about going in dilute sulfuric to dissolve the iron which was, (if I read correctly, {clue there}), should have left me just silver to melt straight up.

So assuming what I have is silver sulfide and I tried to just melt with no flux, would that leave me with the hard black material in the melt dish? Under the torch it went gooey and bubbled, when cooled it's as hard a brick and with a black glassy appearance.

And if it is silver sulfide is smelting with flux and iron the best way to get metal silver?

I won't be able to work on this for a few weeks as work is sending me to Mexico for 2 weeks, but when I get back I'd like a plan of attack.

 

[Harold_V]

I'm mystified why you, or anyone, tries to eliminate steel (iron) from silver sulfide materials. It's essential for recovery, which is the very reason one uses rebar, or other scrap steel. Pretreatment with acid is a waste of time and material.

Dry the material, flux with borax and soda ash, then melt (smelt) the material, along with additional scrap steel. A quick heating with a torch is generally not adequate. It takes some time for all of the silver sulfide to be processed.

When you are successful, there will be a layer of black, shiny slag, covered by a layer of what resembles gray cast iron (iron sulfide), with a button of metal resting at the bottom. This material should be poured to a cone mold, for fast and easy separation from the slag and iron sulfide.

This is an example of when things will stratify. Each layer should have a distinct parting line.

Kurtak---That's a very nice looking furnace!

Harold

 

[rickbb]

Like I said Harold it was probably me, I had read some posts that discussed putting material like this in dilute cold sulfuric which would leave just the silver.

Now I know. Thanks.

 

[kurtak]

So assuming what I have is silver sulfide and I tried to just melt with no flux, would that leave me with the hard black material in the melt dish? Under the torch it went gooey and bubbled, when cooled it's as hard a brick and with a black glassy appearance.

And if it is silver sulfide is smelting with flux and iron the best way to get metal silver?

The flux alone (borax & soda ash) are not what makes the conversion - it needs the iron - did you read the thread that I provided a link to :?:

this smelting process does not work well with melting dishes (which is explained in my linked thread provided in my other post) though it can be done - you really need a gas operated furnace

The conversion can also be done with potassium nitrate - I have never tried this method so can't tell you much about it - I "think" I may have a PDF on my old computer (that was provide by Juan Manuel Arcos back I the early days of the forum) If its on my old computer I will try to provide it - or you can try to search for it through Manuel's profile - it will be something he posted back I the early days of the forum

Kurt

 

[kurtak]

Kurtak---That's a very nice looking furnace!

Harold

Thanks Harold - that's my small one - it does "a lot" of work for me - it due for a re-lining of refractory

Here is a pic of my big one - it takes up to a #40 crucible

I have become a real fan of smelting - don't leach anything from ash anymore - smelting the metals & then doing the chemical work on the metals is a much better way to go in my opinion

 

[rickbb]

The flux alone (borax & soda ash) are not what makes the conversion - it needs the iron - did you read the thread that I provided a link to :?:

this smelting process does not work well with melting dishes (which is explained in my linked thread provided in my other post) though it can be done - you really need a gas operated furnace

The conversion can also be done with potassium nitrate - I have never tried this method so can't tell you much about it - I "think" I may have a PDF on my old computer (that was provide by Juan Manuel Arcos back I the early days of the forum) If its on my old computer I will try to provide it - or you can try to search for it through Manuel's profile - it will be something he posted back I the early days of the forum

Kurt

Yes I've read it. But my problem is I'm not really setup with a decent working furnace. I've tried stacking up some fire brick and lining it with ceramic wool to insulate it and using a roofers propane torch with a small blower to put in some extra air. I did that with the first batch of this material, didn't do very well for me.

I will take another look through Juan Manuel's posts, I've read quite a few of them and believe that's where I read about the dilute sulfuric method. (But obviously I've botched that up.)

I'll get there eventually, if you guys can put up with me long enough that is. :lol: