Can I be forced to work consecutive days until a project is complete?
The United Mine Workers of America (www.UMWA.org) represents workers in the coal industry and the expectations for miners' working hours are usually negotiated and set out in various collective bargaining agreements with mine owners.
Whether or not your employer can force you to work these kinds of hours--or rather, what's considered fair working hours--is probably addressed in their agreement.
Your union is there to protect you and you should bring any grievances (or even questions like this) to your union representative. If you don't know who that is, contact the UMWA--their website has a link to the various district offices, and they can put you in touch with the right person.