I was incorrect in describing the smelter fee example.
What I should have said: Assume that a company that produces 20,000 tonne nickel annually in its concentrates.
With nickel in concentrate grading 10%, the concentrate would weight 200,000 tonne
With nickel in concentrate grading 20%, the concentrate would weight 100,000 tonne
Transport tonnage to the smelter for the 20% concentrate would be half of the 10% concentrate, resulting in transportation savings.
The same would apply to the amount of concentrate going through the smelter, which would be half the amount for the 20% concentrate. In the end, the same amount of nickel 20,000 tonne or 44.09 milillion pounds of nickel minus smelter losses would be produced.