Potassium Feldspar;
Potassium Oxide (K2O3 MA= 94.2)
The most important feature of potassium-containing glazes compared to sodium-containing glazes is the high melting point. Crystal growth is not very active in potassium-containing frits. Normally, potassium needs can be met from Potassium feldspar minerals. Apart from feldspar, K2CO3 and KNO3 are raw materials used as potassium sources.
Tecnodieci potassium feldspar is used as an alkali source to ensure melting in ceramic separators. The difference between potassium feldspar and sodium feldspar is that it has a higher melting point and is also more stable.
However, due to its high expansion, its ratio should be taken into consideration in glaze and body recipes.
Potassium feldspar is almost non-existent in our country compared to sodium feldspar, therefore it is imported primarily from India, Egypt and some European countries.
The important thing in potassium feldspar is the K2O ratio. The K2O value of a good potassium feldspar should be at least 11% and above. The higher the K2O ratio, the more the melting, shining and spreading behavior will be. Of course, the TiO and FeO ratio is also extremely important for color.
Potassium oxide; It is widely used in glass, ceramics, enamel, electroplate, frit, plastic industry.
The main areas of use of feldspar are summarized below:
1. Glass Industry: The glass industry still maintains its position as the largest consumer of feldspar and nepheline syenite. Feldspathic minerals are mainly included in the glass recipe as a source of alumina. However, their flux properties are also useful. The alkalis in the feldspar act as a flux to reduce the melting temperature: alumina provides sensitivity and provides resistance against impact, bending and thermal shocks. To make a broad generalization, in addition to the above benefits, alumina content, which prevents the glass from losing its transparency and increases its viscosity during manufacturing, is present at a rate of 1.5-2% in containers (glass, bottles) and flat glass products. In glass fiber, it can be present at a rate of up to 15% depending on the intended use. Nepheline syenite is an important source of silica (59-60%), alumina (23-24% Al2O3) and alkali (9.8-10.2% K2O). In glass production, nepheline syenite is used as a flux in melting glass frit and constitutes 5 to 15% of the frit in container (vessel) glass. Nepheline syenite is consumed to a greater extent in the production of food, beverage, chemical, pharmaceutical bottles and jars, and to a lesser extent in the production of flat glass, pressed and blown glass products.
2. Ceramic Industry: Feldspathic minerals have played an important role in the formulation of recipes in the ceramic industry for centuries. There is no doubt that in the near future, it will continue to be one of the most important markets for feldspar and nepheline syenite as the end-use area. Fluxes (melters) are added to the ceramic recipe in order to reduce the temperature that will provide liquid formation when the body is fired. The melter (flux) controls the degree of vitrification of the ceramic body during firing and the product leaves the kiln at the desired degree of vitrification. Since different ceramic bodies require different degrees of vitrification, the amount of flux to be used in certain bodies also varies. In soft porcelains (fired at low temperatures), feldspar constitutes 25-40% of the recipe composition; 18-30% in tableware, 20-28% in electroporcelain and 17-30% in chemical-technical porcelain. The amount of fluxes used, such as sodium and potassium feldspar or nepheline syenite, is affected by many technical criteria, and these criteria include the properties to be gained by the addition of a particular flux. Examples of these include the degree of whiteness sought in the final product, tensile strength, glaze retention or rejection, the effect of metalworking on glaze decorations and the traditional habits of the manufacturer. Potassium feldspar is more common in the ceramic industry. The advantage of potassium feldspar is that it forms a highly viscous melt, which, as a result, provides resistance to deformation of the ceramic during firing. Although feldspar is mainly used in ceramic vessels and benches, nepheline syenite has begun to be preferred as a flux in sanitary ware and tile manufacturing.
3. Welding Electrode Production: Welding electrodes are the traditional end-use for feldspars, because their fluxing properties make them an ideal component for making electrode coating materials. Feldspar added to the mixture has two important functions: it acts as an arc stabilizer and protects the weld pit. Materials used as arc stabilizers include metallic additives such as potassium and sodium silicate, clay, talc, nickel and iron powders, in addition to feldspar. These stabilize the arc by forming elements with low ionization potentials. In the case of filling the weld pit, molten feldspar