Hi Damien,
First sort the phones into piles according to the type of screws which hold the plastic together. Get yourself the right types of screwdriver tips for your electric screwdriver. The tiny watchmakers ones- cross-head, star head etc.
Remove all the batteries and store them in a safe way - not in a metal container. Lithium batteries can catch fire or cause explosions if they are punctured or short circuited. You may be able to sell them to a scrapyard. Definitely keep them well away from your acids.
Unscrew the plastic cases with the electric screwdriver. Put all the plastic in a bag to be recycled. All the boards can go in a box, remove the sticky-backed plastic bit which is behind the keypad as you go. This exposes the gold 'bullseyes' as some call them. Also remove the screens and any loose components. Get them as clear as possible manually.
Make a small wood fire perhaps in an old barbeque. Put an old baking tray full of sand on the fire. Lay the boards about 6 at a time on the sand when its hot enough, and use metal tongs to remove them and tap off the surface-mounted components as the solder melts. If you tap them off into some kind of container you can sort through for any gold parts later. Geo has a good video of how to do this: https://www.youtube.com/watch?v=Pn5LjwnmYFg
When the boards are cool, let them sit in hydrochloric acid for about a week to dissolve as much remaining solder as possible. Minimise the amount of oxygen available by keeping them in plastic tubs with lids, full to the brim, with the lid closed loosely. This is to reduce the chances of the HCl making Copper Chloride II solution too soon. You want the gold plating to stay attached to the boards at this stage.
When the boards are free of solder, you can put them into AP to release the gold flakes. You can make AP with fresh HCl, a few strands of electrical copper wire and a tiny tiny bit of peroxide to get it started. Peroxide gives the solution oxygen to start the etching process. Once it starts dissolving the copper in the boards it will not need anything else except air to keep going. Personally I do AP without using a bubbler. This makes it slower but I don't mind waiting and I prefer that any gases will be released at a much slower rate which is less of a hazard.
When you can see all the gold has come off as flakes into the solution, pour off the acid through a filter to collect the gold. What I do is to rinse the filter off into collection jars using water from a spray bottle. Keep the acid as it can be used many times. Also keep the used filter as these can be incinerated later and any remaining fine gold can be recovered.
See the forum for how to refine your flakes later. Be sure to read Hoke and as much of the forum before messing with more chemicals. For now just store the flakes in water in collection jars. Don't worry if there's bits of green solder mask in with them as this gets filtered out later.
Be safe