US4738938A — Melting and vacuum refining of glass or the like …

Claim 1

Independent Claim 77 words

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.

Claim 2

Independent Claim 77 words

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.

Claim 3

Dependent Claim 26 words

The method of claim 1 wherein the molten material is introduced into the subatmospheric space through a valved orifice above the level of the molten material.

Claim 4

Dependent Claim 24 words

The method of claim 1 wherein transport through the body of molten material is predominantly in a vertical direction toward the location of withdrawing.

Claim 5

Dependent Claim 17 words

The method of claim 1 wherein the subatmospheric pressure is no more than one-half of atmospheric pressure.

Claim 6

Dependent Claim 17 words

The method of claim 1 wherein the subatmospheric pressure is no more than one-third of atmospheric pressure.

Claim 7

Dependent Claim 24 words

The method of claim 1 wherein the pressure in the body of molten material at the elevation of withdrawal is at least atmospheric pressure.

Claim 8

Dependent Claim 16 words

The method of claim 6 wherein the rate of withdrawal is controlled by outlet orifice means.

Claim 9

Dependent Claim 20 words

The method of claim 1 wherein material that is newly foamed is deposited onto a mass of foam previously formed.

Claim 10

Dependent Claim 14 words

The method of claim 1 wherein the material being melted and refined is glass.

Claim 11

Dependent Claim 15 words

The method of claim 1 wherein the material being melted and refined is soda-lime-silica glass.

Claim 12

Dependent Claim 15 words

The method of claim 1 wherein the subatmospheric pressure is no more than 100 torr.

Claim 13

Dependent Claim 15 words

The method of claim 1 wherein the subatmospheric pressure is no more than 50 torr.

Claim 14

Dependent Claim 42 words

The method of claim 1 wherein the step of producing a melt of the material comprises rendering batch materials to an incompletely melted flowable state in a first chamber and passing the material to a second chamber where the melting is furthered.

Claim 15

Dependent Claim 26 words

The method of claim 13 wherein the material passing from the first chamber includes unmelted particles, and the particles are substantially dissolved in the second chamber.

Claim 16

Dependent Claim 36 words

The method of claim 13 wherein the material being melted is soda-lime-silica glass, and the material is passed from the second chamber to the subatmospheric space at a temperature no greater than 2700° F. (1450° C.).

Claim 17

Dependent Claim 32 words

The method of claim 15 wherein the material is passed from the first chamber to the second chamber at a temperature of about 2200° F. (1200° C.) to 2400° F. (1320° C.).

Claim 18

Dependent Claim 20 words

The method of claim 13 wherein the material is heated in the second chamber to a temperature suitable for refining.

Claim 19

Dependent Claim 56 words

The method of claim 13 wherein the material being melted is soda-lime-silica glass, and the batch materials are fed to the first chamber with a sulfur source as a refining aid in an amount no greater than an equivalent amount of 2 parts by weight sodium sulfate per 1000 parts by weight of silica source material.

Claim 20

Dependent Claim 29 words

The method of claim 13 wherein the step of rendering the batch materials to a flowable state comprises exposing the batch materials to heat while supported on a slope.

Claim 21

Dependent Claim 13 words

The method of claim 19 wherein the slope encircles a centrally heated cavity.

Claim 22

Dependent Claim 17 words

The method of claim 13 wherein the temperature is increased in the second chamber by electric heating.

Claim 23

Dependent Claim 25 words

The method of claim 13 wherein material flows in the second chamber from an inlet region to an outlet region along a predominantly horizontal path.

Claim 24

Dependent Claim 23 words

The method of claim 1 wherein the withdrawing of molten material from the body is carried out through an orifice of variable opening.

Claim 25

Independent Claim 90 words

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.

Claim 26

Independent Claim 90 words

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.

Claim 27

Dependent Claim 31 words

The method of claim 24 wherein the pressure at the upper portion is no more than one-half of atmospheric pressure, and the pressure at the lower portion is at least atmospheric.

Claim 28

Dependent Claim 23 words

The method of claim 24 wherein the rate at which liquefied material is drained from the vessel is regulated by second valve means.

Claim 29

Dependent Claim 12 words

The method of claim 24 wherein the glassy material is soda-lime-silica glass.

Claim 30

Dependent Claim 32 words

The method of claim 24 wherein, subsequent to being liquefied and prior to passing through the valve means, the temperature of the liquefied material is raised to a temperature suitable for refining.

Claim 31

Dependent Claim 114 words

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.

Claim 32

Dependent Claim 114 words

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.

Claim 33

Dependent Claim 12 words

The apparatus of claim 29 wherein the third vessel is vertically elongated.

Claim 34

Dependent Claim 14 words

The apparatus of claim 30 wherein the third vessel is generally cylindrical in configuration.

Claim 35

Dependent Claim 25 words

The apparatus of claim 29 wherein the second vessel communicates with the third vessel by way of an orifice having flow control means associated therewith.

Claim 36

Dependent Claim 19 words

The apparatus of claim 29 wherein the means to drain material from the third vessel includes flow control means.

Claim 37

Dependent Claim 13 words

The apparatus of claim 29 wherein the third vessel includes a gas-tight shroud.

Claim 38

Dependent Claim 13 words

The apparatus of claim 34 wherein the shroud is provided with cooling means.

Claim 39

Dependent Claim 83 words

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.

Claim 40

Dependent Claim 83 words

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.

Claim 41

Dependent Claim 23 words

The apparatus of claim 36 wherein the inlet means has associated with it means to control the flow rate of molten material therethrough.

Claim 42

Dependent Claim 22 words

The apparatus of claim 37 wherein the outlet means has associated therewith means to control the flow rate of molten material therethrough.

Claim 43

Dependent Claim 13 words

The apparatus of claim 36 wherein the vessel is generally cylindrical in configuration.

Claim 44

Dependent Claim 17 words

The apparatus of claim 39 wherein the vessel is provided with a gas-tight shroud including cooling means.

Claim 45

Dependent Claim 19 words

The apparatus of claim 36 wherein the height of the vessel is no more than five times its width.

Claim 46

Dependent Claim 18 words

The apparatus of claim 36 further including a source of molten glassy material connected to the inlet means.

Claim 47

Dependent Claim 56 words

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 3 .

Claim 48

Dependent Claim 56 words

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 3 .

Claim 49

Dependent Claim 21 words

The product of claim 43 wherein the residual sulfur is less than 0.05 percent by weight measured as SO 3 .

Claim 50

Dependent Claim 18 words

The product of claim 43 wherein the glass has less than one gaseous inclusion per 100 cubic centimeters.

Claim 51

Dependent Claim 18 words

The product of claim 43 wherein the glass has less than one gaseous inclusion per 1,000 cubic centimeters.

Claim 52

Dependent Claim 13 words

The product of claim 43 in the form of a flat glass sheet.

Claim 53

Dependent Claim 19 words

The glass sheet of claim 47 wherein tin oxide is present in surface portions of at least one surface.

Claim 54

Dependent Claim 59 words

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 3 .

Claim 55

Dependent Claim 59 words

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 3 .

Claim 56

Dependent Claim 17 words

The glass sheet of claim 49 wherein the SO 3 content is less than 0.005% by weight.

Claim 57

Dependent Claim 50 words

A sheet of float glass comprising a bulk composition of a soda-lime-silica glass and a concentration of SnO 2 in at least one surface portion greater than the bulk composition; characterized by a residual sulfur content, measured as SO 3 , from a trace to less than 0.01% by weight.

Claim 58

Dependent Claim 50 words

A sheet of float glass comprising a bulk composition of a soda-lime-silica glass and a concentration of SnO 2 in at least one surface portion greater than the bulk composition; characterized by a residual sulfur content, measured as SO 3 , from a trace to less than 0.01% by weight.

Claim 59

Dependent Claim 17 words

The glass sheet of claim 51 wherein the SO 3 concentration is less than 0.005% by weight.

Claim 60

Dependent Claim 36 words

The glass sheet of claim 51 wherein the bulk composition consists essentially of: ______________________________________ SiO.sub.2 72-74 percent by weight Na.sub.2 O 12-14 CaO 8-10 MgO 3-5 Al.sub.2 O.sub.3 0-2 K.sub.2 O 0-1 Fe.sub.2 O.sub.3 0-1 ______________________________________

Claim 61

Dependent Claim 19 words

The glass sheet of claim 53 wherein a surface portion includes at least 0.5% by weight SnO 2 .

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-04-19	1991-10-19	1992-04-19	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-04-19	1995-10-19	1996-04-19	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-04-19	1999-10-19	2000-04-19	$7700.00	Window Closed / Lapsed

Melting and vacuum refining of glass or the like and composition of sheet

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