Re: Banks' own Blockchain?

But will it be a public ledger, can be mined publicly?

I just don't see how it is possible to create a private network and "mine" it.
Makes no sense.

Ripple is different though, as far as I understood. Ethereum has mining, and therefor is public?

Need to read up more on these things later tonight.

No, it wont be public nor will it be mined by the public.
It will save them money and time to confirm money transfers from bank A to bank B.
They will still charge you the same and it will probably take as long for you to "transfer" the money because it makes them more money.

How do they prevent the public from mining it and keep the network safe? maybe a PoS blockchain would make sense and they can hold everything at the beginning?

They will probably give the public a lightweight client, maybe even customer based - compiled at the time of account creation.
There wont be any public mining.
Each bank will have pre-mined coins based on their fiat reserves.
PoS sounds about right but it will have to be thought of very carefully as different banks will offer different interest rates.
But I am guessing it will be along these lines.