A freezing method of shaft sinking, in which a solution of magnesium chloride, MgCl₂, is circulated through the freezing tubes instead of brine. The magnesium chloride is 1720 cooled to about -30 degrees C at the refrigerating plant, and this temperature is capable of freezing the ground without the solution itself freezing and choking the tubes. Anhydrous ammonia, carbon dioxide, or sulphur dioxide is used as the refrigerating agent.