The total amount of heat to be removed from foundry return
sand is a function of the initial temperature of the sand, desired temperature of the cooled sand, weight of sand to be cooled, ambient condition of the cooling air and temperature of the cooling water.
Foundries use these fluxes during the melting of heavily oxidized foundry returns
and machining chips, as well as when metal holding temperature exceeds the 1420-1450F range.
Using these blocks allows a greater proportion of foundry returns
to be melted, permits control of final silicon to lower levels, reduces sulfur and increases residual magnesium without affecting the silicon, and serves as an alternative to nickel-containing nodularizers.
Charges consist of 40-60% foundry returns
with the balance made up of low carbon iron or 1010 steel, ferroalloys and deoxidizers.
Into each magnet-charged charge car, the foundry returns
were placed in the back, the steel scrap in front of the returns and the borings on top of the steel in the front.
Muratore commented on the quality of today's steel scrap, foundry returns
, pig iron, carbon/graphite and ferroalloys.
A standard melt contains a charge of 50% purchased scrap and 50% foundry returns
. A chemistry sample is taken before O injection to determine the necessary C removal.
Foote buys only certified, predried steel punchings, supplemented with internal foundry returns
and virgin pig iron for gray iron and low-sulfur pig iron for ductile iron melting.
Pig iron, foundry returns
and scrap steel are significant sources of N.
Overall heat treating costs illustrate that using pig iron, quality steel scrap and selected foundry returns
is economically justifiable.
Consider purchased foundry returns
. They can be a risk-ridden material, since it may be another foundry's rejects for off-chemistry.
Rose, Duralcan USA, reviewed the status of procedures that have been developed to effectively remove gases and oxides from composite foundry returns