It is probably FeCl2 ferrous not ferric FeCl3, and copper chlorides if the solution is almost black or very dark brown with CuCl, after it has settled well separate the sludge from the liquid, the mud will be where any values are.
At this point it may look like brown powders (CuCl, PbCl, AgCl, gold foils, and any insolubles, solder mask...).
If there is organic material in the liquid, that may be where the smell comes from (I am not sure), I do not remember much smell from the solution normally.
Once you decant liquid from the powders, because I do not know what all the solutions have seen I would try to get values and treat the liquid for waste, much depends on what you have.
If this was a fairly clean solution,(not much tin or trash), you can use the information in the linked post to reuse the Iron/copper chloride solution as described, but if it was too dirty I would just recover values and treat the rest for waste (recovering copper to reuse)...
In a hot plate, a pyroceram dish, add powders and some water, keeping powders stirred bring water up to a boil, lower heat but keep it hot, but let any powders settle well in the water as hot as possible, we want to decant hot to remove the lead, the wash solution may be colored with copper or iron solution, after powders settle decant this wash water into a jar to cool, lead chloride is in boiling hot water is a clear solution, but when it cools it form white lead chloride crystals.
(If by mistake you also transferred some gold flake to this lead jar you could redissolve the lead again later and separate the few flakes of gold and recrystallize the lead again).
Repeat the hot water wash, and decanting aster powders settle, until the wash is clear of color, and you are not getting any lead.
Now from here what my choice of what to do would depend on what these powders were from and what they may contained.
If they had tin, and solder mask, and a lot of trash in solution I would want to incinerate.
If it was mostly clean white CuCl and the values I would wash in HCl converting CuCl to CuCl2 (separate values after settled gold flakes and silver chloride), the decanted CuCl2 could be filtered and reused.
If I decided these powders need incineration, I would try to remove as much chlorides as possible first, as gold incinerated with chloride salt some of the gold could become volatile and go up with the smoke. Cover the powders with water add Sodium Hydroxide (you want to neutralize solution), you can test pH, (if solution is clear of color you are fairly close to the right pH), the sodium hydroxide will neutralize the powders, converting them to oxides (hydroxides), this way copper and silver becomes an oxides giving up the chloride to the sodium to form a soluble sodium chloride salt water which we can rinse out from the settled powders, salt water NaCl does not change solubility much with temperature, but I like to decant rinses as warm as possible after the powders settle, after several washes to was out the salt water from the settled powders, we can dry the powders.
I use a suction bulb, and pipettes to decant liquids from the powders.
Dry powders on low heat, we do not want bubbles to splash out values, so heat as much as possible, but where bubbles do not form and pop and splash out values, if it wants to bubble lower heat. dry powders and raise heat on the pyroceram dish as needed, sometimes these dry powders will fuse and form a liquid syrup again with heat, if this happens again we may have to lower heat if bubbles begin to form until the acid salts are driven off with heat and the powders dry again, they will form a hard crust when dried completely, I normally try to crush the cake before it get too dried, but dry enough to crush to powders, A Pyrex pestal, and using the pyroceram dish as the mortar, after powders are crushed raise the heat to high after it quits smoking I use a torch on the powders keeping them stirred under the torch after they get red hot, this is to expose the red hot powders to air that can oxidize the base metals well.
Let powders cool, wash down sides of dish with the water spray bottle, cover powders is water and give them a hot water wash, decanting the hot wash from settled powders, if wash solution is colored repeat washes till clear.
Cover powders with HCl bring to a boil and lower heat but keep as hot as possible for powders to settle, decant warm HCl wash, if highly colored repeat these washes, and decant solution after powders settle well.
This leaves you with your gold powders or foils and any silver chloride, from here you can dissolve the gold in HCl/NaClO and save any silver chloride in your wet silver chloride jar...
If these Iron/copper chloride solutions are fairly clean we can reuse them, but once we get too much trash in solution we are better off treating them as waste, if we work carefully we can get a lot of use, and work out of a jug of HCl.
Let me know what you think.
