Analysis
HTS 7401.00.00 covers copper mattes; cement copper (precipitated copper) under heading 7401 (copper mattes; cement copper (precipitated copper)).
The normal trade relations rate here is zero, shared by about 12% of the 89 tariff lines in chapter 74, a useful check when a neighbouring dutiable line is a candidate. Duty-free at the general rate does not rule out additional duties under Chapter 99, such as Section 301 or Section 232 measures, which depend on the country of origin.
It is the only US line under subheading 7401.00, so the six-digit code used by every Harmonized System country and the eight-digit US line describe the same goods; a foreign tariff or an exporter's invoice showing 7401.00 points straight here.
Census statistics map these goods to NAICS 331410 (Nonferrous Metal (except Aluminum) Smelting and Refining), an industry of 112 US establishments employing 8,755 people. That concordance is how imports of this line are compared with US output.
Goods from countries without normal trade relations pay the column 2 rate of 6% instead of nothing, so origin decides between free entry and a 6% duty.