Could i somehow get 15-70 or 77 mining in 2 days botting iron or granite?
No, I highly doubt it. I think you can get it in about a week max...not in 2 days...
granite is at least 50k/h.
50k * 48 = about 2500k xp = over 77
so, theoretically if you could manage to get granite at 50k/h, it's easily possible.

