The OP is talking about mixing a small amount (hopefully) of cream of tarter (potassium bitartrate) with orange juice then drinking it.
Doesn't matter what you mix the COT with, the carrier (fruit juice or whatever) is just used to make it palatable enough to swallow.
That and fresh squeezed OJ is already fairly high in potassium and enters your system more rapidly.
Lots of folks quit smoking by chewing gum (non nicotine type) or shell on salted sunflower seeds, or ginger ale with or without added ginger, or using a plastic straw to help with hand to mouth, chew on & take drags through, or dark / bittersweet chocolates, or pickle juice, or hypnosis, or epson salt, or plain ol fashion cold turkey, or even scooby snacks.
It is another completely unfounded method of smoking secession that works for some folks.
Like Shawn Hoefer said, It does pose more health risks & side effects than other hair brained placebo smoking secession methods.
Purposefully ingesting excess potassium is great way to jack your entire system up, your body naturally balances potassium level, messing with that balance is just flat not a good idea.