US 5,846,278 AGranted

Method of determining glass durability

AssigneeWestinghouse Savannah River Company

InventorsCarol Maryanne Jantzen, John Butler Pickett, Kevin George Brown, Thomas Barry Edwards

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Abstract

A process for determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of the glass composition by identifying the components of the glass composition, including associated oxides, determining a preliminary glass dissolution estimator, .DELTA.G.sub.p, based upon the free energies of hydration for the component reactant species, determining an accelerated glass dissolution function, .DELTA.G.sub.a, based upon the free energy associated with weak acid dissociation, .DELTA.G.sub.a.sup.WA, and accelerated matrix dissolution at high pH, .DELTA.G.sub.a.sup.SB associated with solution strong base formation, and determining a final hydration free energy, .DELTA.G.sub.f. This final hydration free energy is then used to determine leachate concentrations for elements of interest using a regression analysis and the formula log.sub.10 (N C.sub.i (g/L))=a.sub.i +b.sub.i .DELTA.G.sub.f. The present invention also includes a method to determine whether a particular glass to be produced will be homogeneous or phase separated. The present invention is also directed to methods of monitoring and controlling processes for making glass using these determinations to modify the feedstock materials until a desired glass durability and homogeneity is obtained.

Claims35

Dependent claims

A process for controlling production of glass, comprising:

A. monitoring production of glass by:
1. determining the composition of glass-forming feedstock materials to be fed to a melter;
2. determining one or more leachate concentrations of one or more components of a glass composition in an aqueous solution of said glass composition based upon said composition of said glass-forming feedstock materials thereby obtaining a one or more determined leachate concentrations by:
a. determining a final glass dissolution free energy change, .DELTA.G.sub.f, comprising:
i. determining the pH of said aqueous solution of said glass composition;
ii. determining the free energy change associated with the dissociation of silicic acid or boric acid or both at said determined pH, .DELTA.G.sub.a.sup.WA ;
iii. determining the free energy change associated with accelerated matrix dissolution at said determined PH, .DELTA.G.sub.a.sup.SB ;
and
iv. summing said .DELTA.G.sub.a.sup.WA and said .DELTA.G.sub.a.sup.SB to obtain .DELTA.G.sub.a, and
v. determining a preliminary glass dissolution estimator, .DELTA.G.sub.p,
b. summing said .DELTA.G.sub.p and said .DELTA.G.sub.a to obtain said .DELTA.G.sub.f ;
and
3. either
a. determining a leachate concentration of said glass composition component in said aqueous solution from the formula:
log.sub.10 (N C.sub.i (g/L))=a.sub.i +b.sub.i.DELTA.G.sub.f
wherein N C.sub.i is the normalized release of said glass composition component in grams of said glass composition per liter of said aqueous solution, and is equal to C.sub.i /F.sub.i, where C.sub.i is the leachate concentration of said glass composition component in said aqueous solution in grams per liter and F.sub.i is the weight fraction (element wt %) of said glass composition component in said glass composition in grams of said glass composition component per grams of glass, and wherein a.sub.i and b.sub.i are constant values for said glass composition component, or
b. comparing said .DELTA.G.sub.f to known values for glasses determined to be stable under the leachate conditions, and
4. comparing at least one of said determined leachate concentrations to an allowable standard for said component of said glass composition, comprising determining the difference between said allowable standard for said component in said glass composition and said determined leachate concentration, and
B. determining whether said difference between said allowable standard for said component in said glass composition and said predicted leachate concentration exceeds a preset value;
and
1. when said preset value is exceeded, introducing said glass-forming feedstock materials to said melter, or
2. when said preset value is not exceeded, adjusting said composition of said glass-forming feedstock materials and redetermining said difference until said preset value is exceeded.

19 more elements

A process for preparing a glass composition at least partially soluble in a body fluid solution, comprising:

A. determining the composition of glass-forming feedstock materials to be fed to a melter;
B. determining a final glass dissolution free energy change, .DELTA.G.sub.f, comprising:
1. determining a preliminary glass dissolution estimator, .DELTA.G.sub.p ;
2. determining an accelerated glass dissolution function, .DELTA.G.sub.a comprising:
a. determining the pH of said aqueous solution of said glass composition;
b. determining the free energy change associated with the dissociation of silicic acid or boric acid or both at said predicted pH, .DELTA.G.sub.a.sup.WA ;
c. determining the free energy change associated with accelerated matrix dissolution at said predicted pH, .DELTA.G.sub.a.sup.SB ;
and
d. summing said .DELTA.G.sub.a.sup.WA and said .DELTA.G.sub.a.sup.SB to obtain said .DELTA.G.sub.a ;
and
3. summing said .DELTA.G.sub.p and said .DELTA.G.sub.a to obtain said .DELTA.G.sub.f ;
and either:
C. controlling said glass composition based upon a leachate concentration of said glass composition component in said body fluid solution, comprising:
1. determining a leachate concentration of said glass composition component in said body fluid solution from the formula:
log.sub.10 (N C.sub.i (g/L))=a.sub.i +b.sub.i .DELTA.G.sub.f
wherein N C.sub.i is the normalized release of said glass composition component in grams of said glass composition per liter of said body fluid solution, and is equal to C.sub.i /F.sub.i, where C.sub.i is the leachate concentration of said glass composition component in said body fluid solution in grams per liter and F.sub.i is the fraction of said glass composition component in said glass composition in grams of said glass composition component per grams of glass, and wherein a.sub.i and b.sub.i are constant values for said glass composition component;
and
2. comparing at least one of said determined leachate concentrations to a minimum desired concentration for said component of said glass composition in said body fluid solution;
and
a. when said predicted leachate concentration of said component is higher than said minimum desired concentration, introducing said glass-forming feedstock materials to said melter, or
b. when said predicted leachate concentration of said component is lower than said minimum desired amount, adjusting said composition of said glass-forming feedstock materials and redetermining said leachate concentration, until said predicted leachate concentration is higher than said minimum desired amount;
or
D. controlling said glass composition based upon said .DELTA.G.sub.f, comprising comparing said .DELTA.G.sub.f to known values for glasses determined to have acceptable solubilities in a body fluid solution.

20 more elements

Dependencies are inferred from the claim text.