The document discusses combustion and roasting exercises. It provides two examples: 1) Calculating air volume needed for combustion of coal in a reverberatory furnace. It is determined to be 8735.0667 m3 of air per ton of coal. 2) Analyzing roasting of a copper ore. Gases produced per ton of ore are calculated based on ore composition and oxidation reactions. SO2 produced is 11.5479 kmol/ton of ore. Excess air is also calculated.