Roy, welcome to the forum. You mentioned that you have tried to follow the advice you've seen on this site, but your profile shows you joined today. Were you a member in the past under a different name? It's not a problem. I was just curious if you were here before you got sick. I'm glad to hear you're feeling better.
I agree with a couple of members that if you can provide pictures of what you have and give us more information about how you got to this point, we'll be better able to help you. You mentioned using nitric to eliminate base metals. Was that part of what ended up in the 55 gallon barrel? You also mention that half the barrel of aqua regia had evaporated, so was it all aqua regia? Was it a full 55 gallons when you got sick, and now there's only about half of the liquid left? Does the barrel just contain the remaining aqua regia and the crystals, or are there still parts of the original cell phone components and other starting material in the barrel? You mentioned that you opened the barrel and found half had evaporated. What kind of barrel is it (steel, plastic, etc.)? What kind of cover did you have on it that allowed half of the liquid to evaporate? I could probably ask another dozen questions, but I'll let you get started with those and provide any other details you can.
If you had a quart or a gallon I might agree with just disposing of it properly, but with a half barrel that could get expensive, and hopefully if you used that much acid, you should have a reasonable amount of values in there. Any mess can be cleaned up, but we need more information to start to steer you in the right direction. I have ideas of how to proceed, but it depends on some of those answers.
You're not the first person to find an old container containing an unknown combination of "stuff". I'm sure you won't be the last. We can use this thread as a learning experience for you, and a teaching experience for those who find themselves in the same situation in the future. Know going in that this will probably not be easy and will take some dedication and effort on your part. If you're up for it, we are too.
Looking forward to some pictures and details.
Dave
Edit to add it looks like Nick posted some of the same thoughts while I was typing.