Insoluble silver compound?

[mitchd]

Hi All,

Long befor I found the forum I disloved 15 or so pounds of 925 silver and some silver from computer cpu's around 5000 mixed with about 2500 amd durans and from the computer parts I recoved about 15 OZ of silver. My problem is that I used home made HNO3 with H2SO4 96% and sodium nitrate and H2O and used my mixture as is, just added this to the 925 silver and it worked but as I found out later by reading post on the forum, by doing this it makes insoluble silver compund and that is just what it did. To see if it was silver I heated about 2 grams up using a propane tourch and did get silver from it with lots of yellow smoke.

My question is what would be the best was to recover silver from this compound? I have about 5 pound of dried compound.

I did find that it did dislove in AR and at least some of it ended up as AgCl.

Any help would be welcome

Thanks

Mitchell.

 

[4metals]

I would take a sample of the already dried mix and incinerate it. Place the residue in 50% nitric acid solution and dissolve the silver. Filter the solution and add either salt or HCl to drop a fluffy white silver chloride which will quickly tell you if the incineration / leach was effective.

The method for the larger mass, if this is effective can vary some as the solution, after filtration, can also be cemented with copper to yield a high purity silver.

Since you did some gold containing boards, the insolubles you filtered off can be further processed in Aqua regia to recover any gold.

 

[butcher]

I like 4metals advice,

I think you formed silver chloride mixed with silver sulfate, either of these would burn off in smoke if you tried to melt.

Another option:

You may try to convert these to silver metal powder, by using a metal lower in series.and dilute sulfuric acid, heat and stirring well.

What I would try is adding dilute H2SO4, and Iron (Clean transformer laminate soft iron, incinerated to remove shellac), heat solution and stir well, the Iron should go into solution as ferrous sulfate, and ferrous chloride, if the process and reaction proceeded (at a greater than the boiling point of HCl), you could actually drive off the HCl formed as gas,(from silver chloride and sulfuric acid forming HCl as silver convert to metal electrons provided by the iron), thus the product solution could be made to be FeSO4, and silver powder, the iron chloride will not hurt if left in solution with the ferrous sulfate, (but I would probably try and form ferrous sulfate and recrystallize it for my lab instead of just disposing of the solution.

 

[mitchd]

Thanks for the replys,

Incineration is more or less what I did with the tourch on my test lot of 2 grams and although I see matlic silver but I can't get it out of the containter and its a stuck on mess, just don't have enough heat to get it to flow out and it wont break or scrape out with out breaking the container. So for me incineration will not work with what I have on hand.

Well I may have not give enough information in my post. The compound of silver has gone through the lye and sugar prosses, then again nitric bath to put the silver powder back into liquid and seperate this compound from the silver, filter out the silver nitrate, heated the filtered out silver sulfate with boiling water and re-filtered to remove any lead. At this point there should be very little silver cloride and mostly silver sulfate.

I started the sulfric acid with iron prosess, about 5 grams of compound and I would say about 10Ml sulfric acid 96% in 200ML of distilled water with a degreased nail that weights about 10 grams and will let you Know if this works.

Thanks
Mitchell.

 

[butcher]

mitchd,

The incineration process and what you did with your torch are two different things, although both use heat.

I also think the NaOH/sugar process would have a hard time converting the silver halide to silver metal when mixed with the silver sulfate, I think you may very well still have silver chloride that the nitric treatment did not get left in these powders.

Much of the lead could have been a sulfate also, so the hot water wash we normally use to dissolve lead chloride may not have rinsed out all of the lead.

Since you have a lot of this material, I would try both methods suggested, on small portions as experimental batches, to see which one would work better, before getting committed to a process on the whole batch, incinerate one as suggested by 4metals, and try the iron conversion with the other, see which performed best.

 

[mitchd]

Here are a few photos on the sulfric acid and iron test, which is going very well with out inceration and with no add heat.
fist photo is the compound which I am having the problem with. #2 photo is the melt to see if there was any silver. #3 photo is
the sulfric acid iron test.
I think I will try this test on a lager scale and with some heat from a burner in a coffee pot.






Thanks for the help and I will let you know how the larger test works out.

Mitch.

 

[butcher]

Mitch,
If you can get the silver salts back to powder for this process (not a large lump of salts), it should work better, as this is more of a contact process, so more of the silver salts in direct contact with the iron the better the chance the iron will have to donate its electron to the silver salt, to convert that silver salt back to silver to metal, also the Iron will take the chloride or sulfate and go into solution in exchange for its donated electron.