Simple Solutions That Work! Issue 5

This furnace is a 35 ton vertical channel furnace melting grey and ductile-base iron. A common insoluble precipitate in initial build-up formation is an Alumino Silicate, 3Al2O3·2SiO2 ( Mullite) A l umi no S i l i ca t e , (Mu l l i t e ) 3Al2O3·2SiO2 Melt temp 3,380°F(1860°C), Gform @2,700°F = -3,177 Cal/mole 3Al2O3 + 2SiO2 => 3 Al2O3·2SiO2 The addition of ½ to 1 pound of flouride-free flux to every furnace charge is extremely beneficial in preventing buildup, evenly distributed throughout. If a flouride-free flux isn’t used, slag buildup will usually proceed more rapidly once the first stages of buildup appear on furnace refractory. For channel holders or pressure pour furnaces, the addition of a flouride-free flux to every transfer ladle will assist in keeping those ladles clean as well as cleanse the metal in the ladle and remove various slag phases from themetal. For such applications, EF40LP in 1 pound bags are recommended. Other considerations for flouride- free flux are on current build up constituents in cast iron applications are shown below. As was previously mentioned, Gibbs Free Energy of Formation helps to identify the possible reactions that can occur first followed by other reactions. HerearesomeexamplesofCalcium Oxide reacting with various insoluble build-up components. Calcium Ox ide on Mul l i te, 3Al2O3·2SiO2 3CaO + 3Al2O3·2SiO2 => 3(CaOAl2O3)·2SiO2 Anorthite @2,700°F Melt temp 2835°F(1557°C) Gform = -33564 Cal/mole Calcium Oxide on Forsterite, 2MgO·SiO2 2CaO·SiO2 + 2MgO·SiO2 => 2 (CaOMgO) · 2S iO2 Di ops i de @2,700°F Melt temp 2,536°F(1,391°C) Gform = -33,922 Cal/mole Calcium Oxide on Sulfur , 2CaO + 2S => 2CaS + O2 (Oldhamite) Melt temp 4,577°F(2,525°C) Gform = -86,573 Cal/mole When considering a flouride-free flux, similar reactions can occur with Sodium Oxide as well. Na2CO3 + SiO2 Na2SiO3 + CO2 Na2O + SiO2 -> Na2O·SiO2 Melt Temp 1,990°F (1,088°C) Na2O + Al2O3 -> NaAlO2 Melt temp 3,002°F(1,650°C) Na2O + Al2O3 -> Na2O·Al2O3 Melt temp 2,469°F(1,353°C) As observed, this fluoride-free flux can readily react with insoluble build-up when used as prescribed. Cast iron foundries can now understand some formation criteria for the daily buildup that they are challenged with. Included were twoexamples for ironmelting and pouring that are common in many cast iron foundries. No longer should there be a negative stigma towards flux usage in cast iron foundries as there are definite benefits for cleaner metal. When used properly, Redux EF40 flouride-free flux can assist cast iron foundries to achieve improved furnace capacity, extended service life and improve metal cleanliness. Improvedmetal cleanliness directly correlates to improvedmechanical properties for the castings. Contact: Rod Naro [email protected] 37