Recover private key from old mining folder

I mined back in 2018 and would like to try to recover the private key. I’ve searched and tried what I could the last few days, but have had no luck. I don't have the recovery phrase. I don't remember getting one and have phrases for all my other wallets, my bad if I didn't save it. I do have the original mining folder including the wallet.dat file. I’ve seen descriptions of people recovering from that file, but so far I have been unsuccessful. So far:

1. Downloaded the latest Raven Core and let it sync, which took most of a day
2. Closed it, copied my old wallet.dat, and replaced the wallet.dat that was created in step 1
3. Opened Raven Core and it had no data
4. Used the re-index option and let that run overnight
5. Still nothing

In console, I tried:

1. dumpwallet wallet.dat – cannot open dump file (code -8)

2. walletpassphrase – running an unencrypted wallet

Any help would be appreciated, not sure what else to try.