I see several problems with that idea.
HCl will react with many metals above Hydrogen in the reactivity series, and the resulting solution will be a combination of these.
It will dissolve tin and break down the lead to a lead chloride powder, to loosen components and other junk, but it can also loosen gold foils in this junk.
Tin in solutions hydrolyze, or oxidizes, especially on standing or with dilution making filtering solution a real problem, and making separations of values from the unwanted material a real problem.
Metals below hydrogen make your solution a dissolved salt of these metals, they also take the hydrogen from the acid to form hydrogen gas that leaves the solution, without this hydrogen you no longer have acid but a salt of the acid and the metal, with this solution you will have several metals in this salt solution that were involved in the circuit board materials.
If using copper II chloride you have an oxidizer that will also dissolve copper, with iron in the circuit you will be displacing copper from the solution,as you dissolve iron in solution your solution will begin to become an iron chloride as well as a mixture of many other base metal chloride salts not only will you still have the problem with tin in solution you will also have much more of the gold foils or powders mixed with the other insoluble trash, as these are freed more easily from the base metals they were plated to...
basically you are making a troublesome mess to deal with to try and recover values from.
You will not have a reusable solution of acid, or copper II chloride, you may have a solution of Iron chloride (and other base metals) you maybe able reuse somewhat in some other recovery procedure, but basically your left with a waste solution that is not very useful loaded with base metals.
You will not be able to just easily remove tin or many of the other metals from this Chloride solution, and even if you could easily remove some of the tin or base metals, you would still be left with a chloride (salt), not (chloric) or hydrochloric acid, with out adding hydrogen back to the solution, in which case you would have to add an acid that defeats your purpose, as you would still be contaminating this acid with base metals...
When you add a metal to an acid you oxidize the metal, at the same time you reduce the acid, this is no longer an acid, and no longer a metal, but a salt of that metal, and a salt of that acid.
Here we reduced the acid to a metal chloride, (hydrochloric --> chloride) notice we lost the hydrogen, notice the ending of the spelling (ic) and (ide) showing us the oxidation state, to go from being a metal chloride, back to hydrochloric acid, we would have to remove all metal from the chloride salt, and oxidize the chloride, add back hydrogen, not something easily done, or worth the trouble especially when buying acid is so cheap...
Not to say that you cannot use this idea, for some things, like when removing memory chips from memory circuit boards (with the gold foils already cut off) so that you can process the memory chips by another process, it will work to do that...
Although time consuming, the best methods of separation are cherry picking separating by hand or mechanical means, and as you will learn from the forum from reading about how others have learned the best way to get the gold separated from the other materials.
Most of your ideas have already been tried and the best way to roll the wheel has become the chosen methods, very seldom will we be able to invent a new wheel, and our best approach is to learn from others what wheel already works best for what we are trying to roll.
As I was writing I noticed Kurt posted the comment (electro winning cell), I have a question on that comment, it is hard to electro win a metal from a solution full of various metals, unless your just trying to push out as much metal out of solution as possible, as a mixture of reduced metals, say like with an inert anode like carbon graphite, and I would not consider that electro-winning , but to form an alkali metal chloride solution, and here you will not get anything but a mixture of reduced metals, and a chloride salt water for all of your trouble...
