632Production of magnesia

#### 632 Production of magnesia (1) The production of magnesia is the chemical and physical transformation of magnesite (magnesium carbonate (MgCO3)) into 1 or more of the following magnesia products: (a) caustic calcined magnesia that: (i) has a concentration of magnesium oxide (MgO) equal to or greater than 75%; and (ii) is burned between 650 °C and 1 200 °C; (b) deadburned magnesia that: (i) has a concentration of magnesium oxide equal to or greater than 85%; and (ii) has grain density of 2.85 g/cm3 to 3.45 g/cm3; and (iii) is burned between 1 300 °C and 2 200 °C; (c) electrofused magnesia that: (i) has a concentration of magnesium oxide equal to or greater than 90%; and (ii) has grain density of greater than 3.45 g/cm3; and (iii) is fused at temperatures in excess of 2 750 °C. (2) The production of magnesia is specified as an emissions‑intensive trade‑exposed activity.