Freezing of the water-flooded zone is made by means of LLC "MСC-Shaftproject" in-house equipment manufactured by ARCTOS Industriekalte AG (Austria).
Freezing plants are easy-to-install container-type assemblies based on screw compressors with an automatic control system. Freon R507 is used as coolant. Plants exhibit high efficiency allowing low-temperature freezing at the temperature down to -38°С.
Plants are cooled by air (water cooling is not required). Formation of ice wall in vertical shafts under construction is monitored by means of high-tech fiber-optic cables laid in three temperature control wells.
Calculation of freezing process is limited to estimation of the freezing station power and the time required for creating an ice wall of the required thickness with specified thermophysical and strain characteristics.
One of the main parameters characterizing the economic feasibility of freezing method is an ice wall thickness: when exceeded, it leads to significant growth of rock amount frozen, when undersized, it leads to destruction of an ice wall and breakthrough of underground waters. Both cases add a lot to the cost and period of underground construction.
After shaft sinking is competed, natural or artificial thawing of rocks is performed against an individual project.
After the ice wall has thawed and all the freezing equipment has been removed, freezing and temperature control wells are to be abandoned. Abandoning shall start only after all shaft lining within the freezing section and waterproofing of tubing lining are completed.