I'm from a large coal mine in Shandong. Personally, I think it is better to do hotel business. Coal miners are very tired when they go to work every day, and their income is ok, so they enjoy eating very much and the price is relatively expensive. As long as the taste is ok, their business will be good and they will make a lot of money. You can also consider cooking Chinese food for underground workers. Supermarkets can also be used, such as selling milk, pickles, sausages and other underground things.