46 CFR §148.225

1. (a)This part does not apply to the shipment of calcined pyrites that are the residual ash of oil or coal fired power stations.
2. (b)This section applies to the stowage and transportation of calcined pyrites that are the residual product of sulfuric acid production or elemental metal recovery operations.
3. (c)Before loading calcined pyrites covered by this section—
   1. (1)The cargo space must be as clean and dry as practical;
   2. (2)The calcined pyrites must be dry; and
   3. (3)Precautions must be taken to prevent the penetration of calcined pyrites into other cargo spaces, bilges, wells, and ceiling boards.
4. (d)After calcined pyrites covered by this section have been unloaded from a cargo space, the cargo space must be thoroughly cleaned. Cargo residues and sweepings must be disposed of as prescribed in 33 CFR parts 151.55 through 151.77.