if you mean 30days of strait gameplay then yeah.
mining coal in the guild is pretty slow xp :\ you're better off doing it in LRC or even granite mining
if you're lvl 3 and in world 84 LRC you will do fine, you can go from 81-99 in 2 weeks 15 hrs a day. i averaged 40kxp with my noob pure even with quite a few deaths.
Yeah, mining coal is very slow. You can still do LRC on a level 3 easy. if you do concentrated Gold Ore from 81 -99, it would take you a round a month.
If you are members why not do LRC gold? A lot better money then coal in the mining guild and you would reach 99 mining in like 20 days (if you bot 24 7, assuming you are botting.)
It possible to achieve 99 mining in 30 days. Though, you need to powermine to 80, then do LRC and be a relatively high level to avoid getting attacked.