There are various places known as "Portaway".
The main Portaway is now, I believe, inaccessible. At least one of the shafts is well and truly blocked with the tailings from 1960s sparring.
Closerake Portaway is accessible if you're brave/stupid enough, but I wouldn't recommend it! I've been there once, which was plenty enough for me. Descending the shaft lands you on a rotten timbered platform ~40' from the bottom. Two ways off, through a small collapse to a small dead-end chamber with an intriguing rise with a brick arched roof, or via a short coffin level to fair sized stope with some truly 'orrible hanging death

Stand still & quiet, & you can hear bits moving! There was clearly quite a bit to it some years back - shame it's in such a nasty state.
Fisher's Portaway is also, I believe, inaccessible these days.
If it's more historical info you're after, I know a few peeps who might have a bit more info.
Z.