Zircon and MgO preheatable insulating refractory liners and methods of use thereof

A method of casting with a vessel which serves to transfer molton metals wherein the vessel is temporarily lined with a preheatable molded refractory insulating liner structure prior to preheating of predetermined shape having insulating porosity, said method comprises the steps of

• providing in the vessel the preheatable molded refractory insulating liner structure of predetermined shape which is suitable for developing sufficient hot strength to maintain the integrity of the structure at vessel preheat and metal casting temperatures which are in the range of about 1900.degree. F. to about 3000.degree. F. wherein the preheatable molded refractory insulating liner structure comprises
• (a) a molded uniform mixture having a substantial insulating porosity on the order of about 50% prior to preheating containing a particulate refractory component in an amount of about 75% to about 98.5% by weight of said preheatable liner structure of a mixture of zircon and MgO refractory grain wherein the zircon and MgO refractory grain are in a ratio of about 1:1.5 to about 1:24, respectively, and
• (b) a binder for the component and inorganic fibrous material in sufficient amounts to maintain the predetermined shape of insulating porosity at least prior to the preheat temperatures wherein the zircon and MgO refractory grain are of a particle size in the preheatable liner structure to facilitate the formation of fosterite bonding which results in increased hot strength with substantial maintenance of insulating porosity and shape without substantial shrinkage at both the vessel preheat and higher metal casting temperatures when the preheatable liner structure is heated for a sufficient amount of time;
• heating the vessel to at least a vessel preheat temperature of about 1900.degree. F. to about 2400.degree. F. to initiate development of hot strength in the preheatable liner structure for casting at metal casting temperatures;
• and
• introducing a molten metal into the vessel with substantial maintenance of insulating porosity and shape of said liner structure without substantial shrinkage.

A method of developing hot strength in a preheatable insulating liner structure of predetermined shape for a tundish comprising the steps of:

• lining the tundish with the preheatable molded refractory insulating liner boards suitable for developing sufficient hot strength to maintain the integrity of the boares at vessel preheat and metal casting temperatures which are in a range of about 1900.degree. F. to about 3000.degree. F. wherein the preheatable molded refractory insulating liner boards comprise
• (a) a molded uniform mixture having a substantial insulating porosity on the order of about 50% prior to preheating containing a particulate refractory component comprised of zircon in an amount of about 10% by weight and MgO refractory grain in an amount of about 80% by weight of the liner structure wherein the MgO refractory grain is derived from about equal parts of about 88% MgO magnesite and about 95% MgO magnesite, and
• (b) a binder for the component and inorganic fibrous material in sufficient amounts to maintain the predetermined shape of insulating porosity at least prior to the preheat temperatures wherein the zircon and MgO refractory grain are of a particle size in the preheatable liner structure to facilitate the formation of fosterite bonding which results in increased hot strength with substantial maintenance of insulating porosity and shape without substantial shrinkage at the vessel preheat and metal casting temperatures when the preheatable liner boards are heated for a sufficient period of time;
• and
• preheating the lined tundish to a preheat temperature of at least about 1900.degree. F. such that as a result of said preheating the refractory insulating tundish board initiates development of hot strength for casting molten metals with substantial maintenance of insulating porosity and shape of said boards without substantial shrinkage.

A method of developing hot strength in a preheatable insulating liner structure of predetermined shape for a tundish comprising the steps of:

• lining the tundish with the preheatable molded refractory insulating liner structure suitable for developing sufficient hot strength to maintain the integrity of the structure at vessel preheat and metal casting temperatures which are in the range of about 1900.degree. F. to about 3000.degree. F. wherein the preheatable molded refractory insulating liner structure comprises
• (a) a molded uniform mixture having a substantial insulating porosity on the order of about 50% prior to preheating containing a particulate refractory component comprised of about 75% to about 98.5% by weight of said preheatable liner structure a mixture of zircon and MgO refractory grain wherein the zircon and MgO refractory grain are in a ratio of about 1:1.5 to about 1:24, respectively,
• (b) a refractory filler which is selected from the class consisting of olivine or zirconia, and
• (c) a binder for the component and inorganic fibrous material in sufficient amounts to maintain the predetermined shape of insulating porosity at least prior to the preheat temperatures wherein the zircon and MgO refractory grain are of a particle size in the preheatable liner structure to facilitate the formation of fosterite bonding which results in increased hot strength with substantial maintenance of insulating porosity and shape without substantial shrinkage at the vessel preheat and metal casting temperatures when the preheatable liner structure is heated for a sufficient period of time;
• and
• preheating the lined tundish to a preheat temperature of at least about 1900.degree. F. such that as a result of said preheating the preheatable insulating liner structure of predetermined shape initiates development of the hot strength for casting molten metals with substantial maintenance of insulating porosity and shape of said structure without substantial shrinkage.

A preheatable molded refractory insulating liner for a casting vessel suitable for developing sufficient hot strength at vessel preheat and metal casting temperatures which are in the range of about 1900.degree. F. to about 3000.degree. F. comprising:

• a liner structure of predetermined shape, said liner structure comprising by weight:
• (a)
• phenol-formaldehyde resin:
• about 2.3%
• hexamethylenetetraamine:
• about 0.2%
• slag wool:
• about 3.3%
• paper:
• about 1.4%
• bentonite:
• about 1.6%
• magnesite-about 88% MgO grade:
• about 40.6%
• magnensite-about 95% MgO grade:
• about 40.6%
• zircon:
• about 10.0%;
• and
• (b) boric acid:
• about 2.5% of dry weight of (a)
• wherein said zircon and magnesites are in amounts proportioned in said liner structure to facilitate the formation of fosterite bonding which results in increased hot strength at the vessel preheat and metal casting temperatures when said liner structure is heated for a sufficient period of time.