Glass batch calculation or glass batching is the determination of the correct mix of raw materials (batch) for a glass melt.
Principle The raw materials mixture for glass melting is termed "batch". The batch must be measured properly to achieve a desired glass formulation. This batch calculation is based on the common linear regression equation
N B = ( B T ⋅ B ) − 1 ⋅ B T ⋅ N G , {\displaystyle N_{B}=(B^{T}\cdot B)^{-1}\cdot B^{T}\cdot N_{G},}
with Nb and NG being the molarities, in the form of 1-column matrices of the batch and glass components respectively, and B being the batching matrix. The symbol "T" stands for the matrix transpose operation, "−1" indicates matrix inversion, and the sign "·" denotes matrix multiplication. From the molarity matrices N, percentages by weight (wt%) can easily be derived using the appropriate molar masses.
Example calculation An example batch calculation may be demonstrated here. The desired glass composition in wt% is: 67 SiO2, 12 Na2O, 10 CaO, 5 Al2O3, 1 K2O, 2 MgO, 3 B2O3, and as raw materials are used sand, trona, lime, albite, orthoclase, dolomite, and borax. The formulas and molar masses of the glass and batch components are listed in the following table:
The batching matrix B indicates the relation of the molarity in the batch (columns) and in the glass (rows). For example, the batch component SiO2 adds 1 mol SiO2 to the glass; therefore, the intersection of the first column and row shows "1". Trona adds 1.5 mol Na2O to the glass; albite adds 6 mol SiO2, 1 mol Na2O, and 1 mol Al2O3, and so on. For the example given above, the complete batching matrix is listed below. The molarity matrix NG of the glass is simply determined by dividing the desired wt% concentrations by the appropriate molar masses, e.g., for SiO2 67/60.0843 = 1.1151.
B = [ 1 0 0 6 6 0 0 0 1.5 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 1 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 2 ] {\displaystyle \mathbf {B} ={\begin{bmatrix}1&0&0&6&6&0&0\\0&1.5&0&1&0&0&1\\0&0&1&0&0&1&0\\0&0&0&1&1&0&0\\0&0&0&0&1&0&0\\0&0&0&0&0&1&0\\0&0&0&0&0&0&2\end{bmatrix}}} N G = [ 1.1151 0.1936 0.1783 0.0490 0.0106 0.0496 0.0431 ] {\displaystyle \mathbf {N_{G}} ={\begin{bmatrix}1.1151\\0.1936\\0.1783\\0.0490\\0.0106\\0.0496\\0.0431\end{bmatrix}}}
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