Melting and vacuum refining of glass or the like and composition of sheet
AssigneePPG Industries, Inc.
InventorsGerald E. Kunkle, Wright M. Welton, Ronald L. Schwenninger
Life of this patent
Estimating the term…
Abstract
Method and apparatus are provided for refining glassy material or the like by vacuum. The material is first melted and then introduced into a vacuum chamber, preferably into space above liquid held in the chamber. Other aspects involve a two-step melting process preparatory to the vacuum refining, in which the material is initially liquefied in one stage and dissolution of particles is substantially completed in a second stage. The molten material is preferably foamed immediately upon entry into the vacuum chamber.
Claims54
A method of melting and refining glassy material or the like comprising:
- producing a melt of the material;
- feeding the molten material at a controlled rate to the upper end of a space maintained at a sufficient pressure below atmospheric to cause the entering material to foam due to expansion of gas content of the molten material;
- gathering molten material from collapsing foam in a body below the subatmospheric space;
- and
- withdrawing molten material from the body.
A method of melting and refining glassy material or the like comprising:
- liquefying batch material;
- passing the liquefied material into the upper portion of a vessel within which pressure below atmospheric is maintained, the liquid being passed through valve means to control the amount of liquid input to the vessel;
- subjecting the liquefied material to reduced pressure within the vessel sufficiently to substantially refine the material;
- and
- draining refined material from a lower portion of the vessel at a selected rate to control the volume of material in the vessel.
Apparatus for melting and refining glassy materials or the like, comprising:
- a first vessel having means to heat batch material to a flowable condition and means to drain liquefied batch material therefrom directly upon attaining the flowable condition;
- a second vessel adapted to receive the liquefied batch material from the first vessel and adapted to substantially complete dissolution of particles in the liquefied material;
- and
- a third vessel having an inlet in its upper end mounted to receive the heated material from the second vessel at an upper end, means to impart and maintain subatmospheric pressure within the third vessel, and means to drain refined material from a lower portion of the third vessel.
Apparatus for melting and refining glassy materials or the like comprising a vertically elongated vessel adapted to hold a body of molten glassy material, inlet means at an upper end of the vessel adapted to pass molten glassy material into a space above the molten body in the vessel, outlet means at a lower portion of the vessel adapted to pass molten glassy material from the vessel, and means to impart and maintain a subatmospheric pressure to the upper portion of the vessel.
A soda-lime-silica flat glass product comprising:
- ______________________________________ SiO.sub.2 70-74 percent by weight Na.sub.2 O 12-16 CaO 8-12 MgO 0-5 Al.sub.2 O.sub.3 0-3 K.sub.2 O 0-3 BaO 0-1 Fe.sub.2 O.sub.3 0-1 ______________________________________
- characterized by a residue of a sulfur-containing refining aid from a trace to an amount less than 0.01 weight percent measured as SO.sub.3.
A sheet of transparent flat glass suitable for vision glazing consisting essentially of
- ______________________________________ SiO.sub.2 70-74 percent by weight Na.sub.2 O 12-16 CaO 8-12 MgO 0-5 Al.sub.2 O.sub.3 0-3 K.sub.2 O 0-3 BaO 0-1 Fe.sub.2 O.sub.3 0-1 ______________________________________
- characterized by a residual sulfur content from a trace to no more than 0.01% by weight measured as SO.sub.3.
A sheet of float glass comprising a bulk composition of a soda-lime-silica glass and a concentration of SnO.sub.2 in at least one surface portion greater than the bulk composition;
- characterized by a residual sulfur content, measured as SO.sub.3, from a trace to less than 0.01% by weight.
Dependencies are inferred from the claim text.