Section 05 Mineral products 26 Ores, slag and ash 26 20 Slag, ash and residues (other than from the manufacture of iron or steel) containing metals, arsenic or their compounds. 26 20 21 Leaded gasoline sludges and leaded anti-knock compound sludges Commodity Code Description 26 20 21 00 Leaded gasoline sludges and leaded anti-knock compound sludges