CHAPTER III. ?
CONSTRUCTION OF BLAST FURNACES. f
In the first days of furnace practice the necessity for good deep foundations was not realized as at the present day. If deep excavations were now to be made i under many of the old furnaces tons of iron might be ; found. Past experience, dearly bought, has taught the furnaceman to provide reliable foundations. In I some localities the depth required is greater than in j> others, and in some cases piles have to be driven ! before the foundation is started. In the furnace shown, Fig. 6, the stone-work illustrated is about five feet deep, on top of which a bed of fire-brick about p five feet deep is laid before the bottom or bed of the furnace is reached. Such foundations are costly, but it has been found wiser to have capital lying idle in them than in lost iron.
Generally no boiler casing; is now used to support that portion of the hearth and bosh which incloses the tuyeres and water coolers V. This portion of the furnace has its fire-brick work supported by means of wrought iron bands, six inches wide by one inch thick, which encircle this portion at the height of every two feet, as seen at S. One idea of not encasing this part with solid boiler plates riveted together, as is done ™
with the upper part of the furnace as shown, is so as to make the placing and attachment of coolers convenientaise the phosphorus too high, which for foundry iron is not so objectionable;, in fact, foundry iron often requires high phosphorus. It can be said that a few are now using steel cinder in making