One can see from the data of Table 4 that carrying out of reduction process under acid slag
is characterized by high degree of phosphorus and sulfur transition into the metal.
For determining conditions of the most complete transition of chrome from ferronickel into acid slag
we shall write down reactions of silicon and chrome oxidizing in the following form:
* produces a slag high in silica from the beginning to maintain an acid slag
throughout the heat.
In order to maintain an acid slag
(50% minimum silica), there must be at least 15-25 lb of sand/ton of iron coming along with the sprue.
All of the acid slag
is tapped into the pouring ladle for its insulating value and ease of removal.
Larger foundries showed a growing preference for acid slag
cupola melting, while the use of direct arc and channel furnaces as primary melting units declined.
Because acid slags
cannot dissolve significant amounts of S, the higher basicity produced in studies A and B was not reflected in lower S levels.
Acid refractories are not as stable as basic refractories, and acid slags
that are produced in such furnaces do not offer the same opportunities for producing clean steel.