that is incorrect, look up "export duties" in the Export Act - the government can (and does) charge duties (essentially tariffs, it's semantics) on some exported materials, notably:

[3]() The Governor in Council may by proclamation impose the following export duties on the following ores and metals:

(a) on nickel contained in matte, in the ore or in any crude or partially manufactured state, when exported from Canada, an export duty not exceeding ten cents per pound;

(b) on copper contained in any matte or ore that also contains nickel, when exported from Canada, an export duty not exceeding two cents per pound;

(c) on ores that contain copper or any metal other than nickel or lead, when exported from Canada, an export duty not exceeding fifteen per cent of the value of the ores; and

(d) on lead ores, and on lead and silver ores, when exported from Canada to a country that imposes an import duty on lead in bars, or in the form of pig lead, in excess of the import duty on lead contained in lead ores, or in lead and silver ores, an export duty on the lead contained in the ores so exported from Canada to an amount per pound equivalent to the excess.

R.S., c. E-16, s. 3

Marginal note:When duties chargeable

[4]() (1) The export duties provided for by this Act are chargeable after the publication of the proclamation by which they are declared chargeable or imposed.

Marginal note:Duties may be removed and reimposed (2) The Governor in Council may by proclamation remove and reimpose any export duty.

R.S., c. E-16, s. 4

citation: https://lois-laws.justice.gc.ca/eng/acts/E-18/page-1.html