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Q: Process for removing organic impurities while melting mineral compositions?

A：In the process for the melting of mineral compositions in preparation for their transformation into fibers e.g. glass, calcium peroxide is added to the batch of vitrifiable mineral components in the melting furnace to provide a low temperature oxidizing environment. The calcium peroxide may be added to the batch materials prior to their introduction into the furnace, or may be added directly to the furnace along with the mineral components. However, it is generally preferred that the calcium peroxide be premixed with the mineral components prior to their introduction into the furnace to ensure that the calcium peroxide is substantially homogeneously distributed throughout the composition. The calcium peroxide is preferably added to the composition in an amount up to about 5% by weight of the total composition.

 

As the temperature of the batch reaches about 575 - 600.degree. F. (301.7 - 315.6.degree. C.), the calcium peroxide begins to decompose into oxygen and calcium oxide. Decomposition of the calcium peroxide generally peaks at about 700.degree. F. (371.1.degree. C.). Accordingly, when the glass batch reaches such temperatures, oxygen is released from the calcium peroxide and creates an environment favorable for the oxidation of any organic impurities contained in the glass batch. Importantly, since the glass batch is still well below its melting point, the gaseous by-products of such oxidation, as well as any excess oxygen released from the calcium peroxide decomposition, are able to pass through the granular batch material and escape without forming an insulating layer that impedes melting of the batch. Further, by removing the organic impurities prior to melting of the mineral composition, the presence of carbon in the molten composition is reduced, which tends to reduce SO2 off gassing and to decrease the propensity for foam formation in the molten mineral composition.

 

As the temperature of the glass batch increases further within the furnace, the remaining calcium oxide dissolves into the molten glass. As a result, no residues are generated which undesirably affect the quality of the glass, nor are potentially environmentally unfriendly by-products generated by the decomposition of the calcium peroxide oxidizing agent.

A：In the process for the melting of mineral compositions in preparation for their transformation into fibers e.g. glass, calcium peroxide is added to the batch of vitrifiable mineral components in the melting furnace to provide a low temperature oxidizing environment. The calcium peroxide may be added to the batch materials prior to their introduction into the furnace, or may be added directly to the furnace along with the mineral components. However, it is generally preferred that the calcium peroxide be premixed with the mineral components prior to their introduction into the furnace to ensure that the calcium peroxide is substantially homogeneously distributed throughout the composition. The calcium peroxide is preferably added to the composition in an amount up to about 5% by weight of the total composition.

 

As the temperature of the batch reaches about 575 - 600.degree. F. (301.7 - 315.6.degree. C.), the calcium peroxide begins to decompose into oxygen and calcium oxide. Decomposition of the calcium peroxide generally peaks at about 700.degree. F. (371.1.degree. C.). Accordingly, when the glass batch reaches such temperatures, oxygen is released from the calcium peroxide and creates an environment favorable for the oxidation of any organic impurities contained in the glass batch. Importantly, since the glass batch is still well below its melting point, the gaseous by-products of such oxidation, as well as any excess oxygen released from the calcium peroxide decomposition, are able to pass through the granular batch material and escape without forming an insulating layer that impedes melting of the batch. Further, by removing the organic impurities prior to melting of the mineral composition, the presence of carbon in the molten composition is reduced, which tends to reduce SO2 off gassing and to decrease the propensity for foam formation in the molten mineral composition.

 

As the temperature of the glass batch increases further within the furnace, the remaining calcium oxide dissolves into the molten glass. As a result, no residues are generated which undesirably affect the quality of the glass, nor are potentially environmentally unfriendly by-products generated by the decomposition of the calcium peroxide oxidizing agent.