Does an employer have to hire a certain amount of females if they are a mostly male company?

I just took coal mining classes and my instructor told me that a coal mine around here has NO female employees. I am wondering if I apply for the job, Can they decide to not hire me because i am a girl?... from what i hear the took the ladies shower room and turned it into an office (the HR guys office btw) I am concerned i wont get hired :(