I managed to get the Genkey part working by referring to Russian guide instead: https://arcticcoin.org/ru-RU/guides-goldmine (google translate)
How to close Goldmine?
For the convenience of holders of Goldmine, in order not to accidentally spend coins for which Goldmine was launched, by default in the settings of the purse Arctic Core, these coins are blocked and they can not be spent.
In order to close Goldmine and start using these coins again, just delete the entry from the goldminenode.conf file for the Goldmine you want to close.