Ok this could technically be possible but the whole web mining thing is a complete scam. You could just run a program to check hundreds of wallets every second. I made one which you can find here at my github repo https://github.com/Grantrocks/addressgenluck. It does work and I was lucky enough to get 1 wallet with about $10. I have been running it for about 9 days. But the chances of getting one are very very very very low. look it up its almost impossible. And you can also configure the program to send the private keys to a private database. If you dont want this just delete it out of the program.