When a carbon dioxide is in a solid form, it is called dry ice. It does not melt, instead the solid turns directly into gas as the temperature rises and solid starts to separate. This unique feature of dry ice results in a smoking effect and it appears to be steaming while it sublimates. Dry ice is commonly used to stimulate smoke or fog.
First, carbon dioxide is molten or liquefied by compacting and cooling. Liquefying at pressure approximately of 870 lbs per inch squared at room temperature. The liquid carbon dioxide is pumped into large holding tanks in order for the manufacturers to remove the required liquid.
The liquid carbon dioxide will be shipped in large quantities, sometimes weighing in tons. Most dry ice manufacturers select to settle their factories close to ammonia or petroleum refineries to make the costs of transportation affordable.
Then the liquid carbon dioxide is released by piping form the adjacent tanks through the wall of the factory into dry ice press. When the liquid moves from high pressured environment to atmospheric pressure, it will expand and evaporate at rapid speeds. This would cause the liquid to cool into its freezing point which is -109 degrees F. The nozzle places the liquid to the top block of dry ice press that approximately stands to 16 ft tall. The press integrates large block at the top which could exert extreme pressure on the product brought into it. As soon as the liquid carbon dioxide hit the block of the press, it will immediately solidify because it is now at room temperature. This is where the carbon dioxide resembles snow.
The snow which is in the upper part of the press should be compressed into block of dry ice. The top portion will go up and down with pressure and squashing the snow in solid block of dry ice. When the block is solid, it is about 2 ft wide and 10 in high and weighs about 220 lb.
Smaller blocks are placed in containers keeping the block cold for the sublimation is kept to minimum. The formation of dry ice is a series of chemical reactions.