Author Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 Excerpt:...fuel or additional blast-heat the slag is likely to become so stiff that it can no longer be withdrawn from the furnace and the interruption to operation which results may last from twelve hours to many days. 1.70 1.00 PER CENT LIME 1.50 1.40 1.30 1.20 SILICATE DEGREE i.W 1.00 0.90 FIG. 3--MELTING-POINT CURVE--FLUIDITY CURVE Before this chain of events was thoroughly understood, and especially before it was realized that if the percentage of lime exceeded a certain amount, the desulphurization became worse and not better, because the stiffness of the slag more than outweighed its greater basicity, furnaces were frequently "lime set," that is, reached the point where the slag became nearly or quite infusible, and freezing up around the walls of the furnace prevented the iron from being withdrawn on one hand, and the ingress of the blast on the other. Stopping the supply of blast resulted in stopping the combustion of the coke and the generation of heat; this, of course, quickly exaggerated a condition already very serious and the furnace became entirely frozen up. In more than one case when the furnace was watered down preliminary to shoveling out, the quantity of lime in the hearth under these conditions was so great that it burst the structure. Many such cases have occurred in quite recent years and even down to the present time furnaces not infrequently come perilously close at least to the early stages of this condition. It will be seen, therefore, that a coke furnace must be driven along a narrow path like that on the side of the mountain. If we deviate from the course on the upper side our progress is stopped and damage may result. If we go too far the other way we plunge to destruction at a rapid rate. The elements with which we have so far...