At our Brassington Moor Quarry, we produce calcium carbonate grades suitable for the production of commercial glassware and ceramics.
Most commercial glasses are essentially a blend of silica, soda (Na2O) and lime (CaO). Lime can also be partly replaced by magnesia (MgO) depending on the final application. To introduce these minerals to the glass melt, manufacturers will add either limestone (CaCO3) or dolomite [CaMg(CO3)2], the former being available in high-purity form from Longcliffe.
Container glass
Container glass, used to produce bottles and jars, is made from a specific mixture of sand, soda ash, limestone and other additives.
Limestone for glass-making must be of a very high purity and contain <0.035% iron oxide (Fe203). Iron is a serious impurity that can adversely affect the colour of the glass. At Longcliffe, our high-purity limestone quarry stone is suitable for the glass industry and contains extremely low levels of metal contaminants.
Flat Glass
Most flat glass is similar in composition to container glass except that it contains a higher proportion of magnesium oxide. Consequently, most lime is introduced using dolomite and only a little limestone is used to balance the CaO/MgO ratio.
The majority of flat glass is used in the production of high-quality glazing for homes, commercial and public buildings, vehicles, and horticultural applications.
Ceramics
Calcium carbonate has traditionally been a source of CaO in raw glazes and it can also be used in low-fire bodies to reduce fired shrinkage. It is also common to see calcium carbonate included in porous earthenware body recipes to prevent moisture expansion which otherwise causes glazes to craze.
The limestone grades available from Longcliffe are suitable for all glass and ceramics applications. Browse our product list or
contact our sales team for further information.