** Canadian steel producer’s shares down 2.3 pct at a 4-week low of C$24.34
** Donald Trump’s administration imposes tariffs on aluminum and steel imports from Canada, Mexico and the European Union, ending a two-month exemption
** Trump on March 23 imposed a 25 pct tariff on steel imports and a 10 pct tariff on aluminum, but granted temporary exemptions to Canada, Mexico, Brazil, the EU, Australia and Argentina
** Tariffs make imports of steel and aluminum less attractive in the U.S.
** So far this year, STLC has risen 6.3 pct (Reporting by Anirban Paul)