What is the difference between roasting and calcinations? Give one example for each?

When do we use a magnetic separation method for concentration of an ore? Explain with an example?

Write short notes on each of the following:

i) Roasting ii) Calcinations iii)Smelting.

Define the temp i) gauge ii) slag.

Magnesium is an active metal if it occurs as chloride in nature, which method of reduction is suitable for its extraction?