31. The proprietor of a private salt factory who has by virtue of a sanad granted by the Government or any former Government, a special and permanent right to manufacture salt, or to excavate or collect natural salt, shall on application made in accordance with the rules made under this Act be entitled to a licence for such purpose and to the annual renewal thereof, unless on a breach of the provisions of this Act, his licence has been cancelled by an officer duly empowered by the ¹[Board] in this behalf.