447
OF ENGINEERING FORMULÆ.
Steel RUnt'FACTurf—continued.
The Pernot furnace bed is mounted on wheels so as to be
moved out of the furnace (which is of the ordinary regenera-
tive gas type), it has its axis inclined at an angle of 5° or 6°
from the vertical and revolves about twice per minute, is
about feet internal and 9 feet external diameter and 18
inches'in depth.
Pernot’s Revolving Open Hearth.
The pig iron previously heated to redness in an auxiliary-
furnace is spread uniformly over the bottom, and upon thia
the whole quantity of steel rail ends or scrap is charged at
once. As the bed revolves the fusion is very rapid; the whole
mass is liquid within 2 hours; samples are taken out at
intervals, and when the metal is ready spiegeleisen or ferro-
manganese is added. The average work of the furnace is
5 charges in 24 hours, and 21 per cent, pig iron, 67 per
cent, scrap, 9 per cent, spiegel, yield about 4i tons. Loss
from 6 to 7 per cent., consumption of coal 8 to 8$ cwt. per
ton of steel.