The secretary is hereby authorized to have trained and employed at the rescue stations operated by the department, such rescue crews as he may deem necessary. Each member of a rescue crew shall devote adequate time for training purposes as determined by the secretary, and shall be available at all times to assist in rescue work at explosions, mine fires and recovery work. Members of the mine rescue crews shall be compensated at rates commensurate for the area as determined by the secretary and payable on requisition approved by the secretary, and such other sums, to be paid by the operating company, as may be agreed upon when engaged in rescue work at explosions, mine fires or recovery work. The secretary may remove any member of a rescue crew at any time.