I have a 1922 silver half dollar with scotch tape on it. The tape has been on it 50 years plus. It’s dried out and totally adhered to the coin. I’ve soaked it in lemon essential oil and googone but still a lot of tape left, adhered to coin. Impossible to get off. What will melt tape but not damage silver coin?
I'll assume that the coin is circulated so a very gentle cleaning won't be a problem. You want to use some sort of organic solvent to loosen the glue, then very gently rub the residue off. You don't want to use any sort of silverware polish or anything abrasive when rubbing the coin.
Good solvents might be olive oil or nail polish remover. After the organic solvent wash the coin with dish washing liquid, rinse with plain water, then dry by flipping coin over on a dry cloth or paper towel.
If the coin is uncirculated then you would want to use an ultrasonic bath with an organic solvent to prevent scratches on the coin.
Two tone coin after cleaning
Because the surface of the coin would have been sealed where the tape was, it is possible that the coin will have a different color where the tape was. If that is the case then you might need to use a coin dip to get the surface looking even again. Unfortunately this will leave the surface shiny which screams that the coin has been cleaned. The coin will dull over time but never really develop a natural patina again since a truly natural patina also depends on wear.
Have you tried olive oil? Smooth over surface of coin generously, leave overnight on a rag inside of plate to prevent seeping to anything you don't want oil on. The following day, use a microfiber rag to buff off the tape.
Add a little more oil sparingly if needed while buffing.
I had tape and adhesives from my old military bags get stuck to everything inside over a course of a decade; metals, plastics, everything. Olive oil did the trick soaking overnight and buffing off in the morning.
As MaxW noted, and as confirmed by any 'Red Book', there are no 1922 Walking Liberty half dollar coins. So you either have 1) a date typo or 2) the coin is worn enough to make the date hard to read. In the latter case, the coin may be below G-4 (Good) condition. If it is a 1921 (P, D or S mint) Walker, it is (or was: see below) worth well over spot silver value, e.g., the 1921 from the Philadelphia mint is worth 180 USD in G-4 condition (as per my 2010 Red Book). The 1921-S is the least valuable: 50 USD for a specimen in G-4 condition. This is more or less: estimates change and a coin is really only worth what you can actually sell it for, which is typically below the Red Book listing.
As for cleaning, this is an absolute no-no unless 1) the coin is of sufficiently high numismatic rarity/value/interest and 2) the cleaning would have to be done by numismatic professionals, e.g., PCGS or NGC. Amateur cleaning causes coin values to drop like lead balloons full of radon. Could you post a photo of the coin, please?
If you ultimately go with buffing, a soft cotton cloth (or Dremel buffing bit!) plus Mothers Mag & Aluminum Polish will shine it up to ludicrous brightness.