The furnace has, in addition to the usual tuyeres near the bottom, a second set near the throat in order to effect a complete oxidation of all combustible matter.
at the tuyeres, with a working height of 17-20 ft., will put through in twenty-four hours, with twelve men, 12% coke and 2 lb blast-pressure, 85 -100 tons average charge, i.e.
at the tuyeres, is about $3.
The furnace consists of a shaft, circular (or more rarely rectangular) in plan, into which alternate layers of fuel and ore are charged, an air blast being generally injected near to the bottom of the furnace through one or more tuyeres.
holes or " tuyeres " near the bottom or " hearth," and through the melting away, by the heat thus generated, both of the iron itself which has been deoxidized in its descent, and of the other minerals of the ore, called the " gangue," which unite with the FIG.