Whenever an employer has complied with the provisions of Section 42-5-20 relating to self-insurance, the Commission shall issue to such employer a certificate, which shall remain in force for a period fixed by the Commission. But the Commission may, upon at least sixty days' notice and a hearing to the employer, revoke the certificate upon satisfactory evidence for such revocation having been presented. At any time after such revocation the Commission may grant a new certificate to the employer upon his petition.