Test the stock pot solution with stannous chloride.
NaCl Sodium Chloride is soluble in water just about as soluble in cold as hot, at this point using cold water would be best, so you do not pick up lead chloride see below.
Cold water to dissolve the sodium chloride salts, let anything that is insoluble settle, and decant the solution for waste treatment.
Lead chloride is almost insoluble in cold water, but becomes much more soluble in boiling hot water, You want the water as hot as possible to dissolve the lead salts, but not boiling as the silver salts are fluffy and will take time to settle, keeping the water hot so lead stays in solution and the silver chloride has time to settle.
Because you used iron you would have cemented base metals that may have been involved, out of solution, cadmium, cobalt, nickel, tin, lead, antimony, arsenic, bismuth, cooper, silver and mercury, as well as any precious metals.
If you would have cemented with copper, most of these base metals stay in solution as they are more reactive than copper, and beside some copper you would only cement the precious or more valuable metals and silver.
Because you have chloride and nitrate salts involved you can make aqua regia by adding an acid to the salts, so testing solutions is needed to insure your not putting your value in solution...
Here I would consider a wash in sodium hydroxide solution, then hot water washes, drying the powders, bringing the heat up slowly, to drive of acid fumes, before bringing the powders to a red hot incineration keeping the crushed and stirred to expose them to plenty of air.
The NaOH wash will help to neutralize salts, along with the hot water washes to help remove as much water soluble nitrates and chlorides as possible, the caustic solution will also help to form, or convert many of the metal chloride and nitrate salts to oxides or hydroxides of the base metals, the heating process and incineration will drive off previous acids and finish the base metal conversion to oxides.
(Silver and gold chloride salts if directly incinerated, you take the chance of loosing some value in the smoke, with the hydroxide and hot water wash can help lower possible lose here).
Copper Chloride, copper oxide, and many of the base metals oxides will dissolve in HCl, silver chloride will stay insoluble. Testing with stannous chloride will indicate if you are dissolving any gold or platinum or palladium.
Heating solutions will pick up more metal and give better results with your acids.
For a better understanding of using the stock pot and recovery of values, study Hoke's book and the forum, the stock pot can be a healthy piggy bank, those who work with many small batches loose a little value in each batch, which add up to a lot of value in the waste solutions, the stock pot can help you to recover these values.
Copper chloride CuCl is pretty much insoluble in water, but dissolves in HCl.
