I work for an underground mining company. Do I have to work longer than eight hours a day? July 28, 2021 22:00 Missouri law states it is unlawful for any operator engaged in mining or prospecting for minerals to work any employee longer than eight hours in a 24 hour time period without his/her consent. Related articles Can an employer require its employees to work more than eight hours a day or more than 40 hours per week? I am a contractor. Do I need training?