The US imposes huge tariffs on Chinese imports of a key raw material.

A trade association representing U.S. graphite producers filed petitions in December with two federal agencies demanding investigations into whether Chinese companies violated anti-dumping laws .

According to the American Active Anode Material Producers, the trade organization that filed the complaint, the new duties will be added to existing rates, increasing the effective rate to 160% .

The Commerce Department said in a preliminary ruling issued Thursday confirming the anti-dumping duties that a final ruling should be announced by December 5.

Donald Trump announced on Wednesday that about "150 small countries with which the US does little business" will soon receive letters informing them of the new tariff rate, which is to be the same for all countries in this group.