Pidgeon method magnesium smelting process principle: Pidgeon method produces metal magnesium with calcined dolomite as raw material, ferrosilicon as reducing agent and fluorite as catalyst, and the batching is carried out. After grinding, it is pressed into balls, called pellets. Put the pellets into a reduction tank, heat to 1200°C, and evacuate the interior to 13.3Pa or higher, then generate magnesium vapor. Magnesium vapor forms crystalline magnesium in the condenser at the front end of the reduction tank, also known as crude magnesium. Refined by flux to produce commercial magnesium ingots, that is, refined magnesium.
The Pidgeon method is an important method for the production of magnesium metal, because the Pidgeon method has a short process flow, less investment, quicker plant construction, and lower cost, but the smelting technology is relatively backward, the resource and energy consumption in the production process is relatively large, and the pollution is relatively serious .
Magnesium production process by Pidgeon process
(1) Dolomite calcination: Dolomite is heated to 1100-1200°C in a rotary kiln or a shaft kiln, and calcined into calcined white (MgO•CaO).
(2) Batching and making balls: Calcined white, ferrosilicon powder and fluorite powder are used to measure and mix, grind, and then press into balls.
(3) Reduction: Heat the pellets in a reduction tank to 1200±10°C, and keep it for 8 to 10 hours under a vacuum of 13.3 Pa or higher. Magnesium oxide will be reduced to magnesium vapor, which will become crude magnesium after condensation.
(4) Refining ingot casting: heating and melting crude magnesium, refining it with a solvent at a high temperature of about 710°C, and casting it into magnesium ingots, also known as refined magnesium.
(5) Pickling: Clean the surface of magnesium ingots with sulfuric acid or nitric acid to remove surface inclusions and make the surface beautiful.