There are manufacturers of pure CO ₂ resource processing kiln gas does not exist, but generally light calcium is needed kiln manufacturers of CO ₂ in the air. Out from the kiln kiln temperature is generally 120 ~ 150 ℃, kiln gas to be cooled first. Cooling kiln gas can be cooled with water. The disadvantage is not kiln gas heat utilization. A better approach is to make the kiln jacket from top to bottom of the kiln Metallurgical Rotary Kiln      trachea, water-cooled furnace gas, clean cooling water heat exchanger section after sending digest digest lime. The main components of the kiln gas is N2 and CO ₂, followed by some CO, O2, water vapor, SO2, tar and soot, it is required in the production of CO ₂, to find a way to SO2, tar and soot removing other components may not be considered. Kiln gas purifying process is physical, using a combination of dry and wet method is preferred to purify the kiln gas. The first stage to remove most coarse dust, the second stage to remove the remaining thick smoke, and then removed by spraying with a cyclone dust collector with inertial dust smoke and most smaller fraction of the SO2; then sieve board to remove the remaining fine dust tower of smoke and most of the SO2, and finally with coke adsorber to remove tar.