Democratic Sentinel, Volume 21, Number 33, Rensselaer, Jasper County, 13 August 1897 — Utilizing the Freezing Process. [ARTICLE]

Utilizing the Freezing Process.

In mining for gold In Siberia the ground Is kept clear of snow, so as to permit the cold to penetrate as deeply as possible, after which the surface Is thawed by fires until a shallow layer of earth can be removed. The freezing Is then allowed to proceed, and the thawing operation repeated, and this is con« tinned as long as the cold weather lasts. In this way, through the long Siberian winters, open excavations are made to the gold-bearing rocks, the depth attained being from twenty-five to seventy-five feet, according to the duration of the cold season. Artificial cold for purposes of excavation was first used by Poetsch in 1883; by his well-known process of the circulation of cold brine through a series of buried pipes the most difficult quicksand may be made hard enough to be excavated like rock. In the article under consideration are given general illustrations and details of the apparatus used in sinking the shaft at the Courrieres mines, together with formulas enabling the safe thickness of frozen wall to be computed for round or square shafts <tf any glfen dimensions. Among the Important applications of the freezing process are noted the sinking of the shafts for the cylinders of the hydraulic elevator for the canal lift at Les Fontlnettes, and the construction of a tunnel at Stockholm. The latter work was executed entirely by the introduction of cold air into the working chamber at the head of the tunnel, the cold preventing the infiltration of water until the beton lining was built, and the work of excavating and mining being carried on at temperatures ranging between zero and 25 degrees Fahrenheit.—Engineering Magazine.