It can be assumed that by reducing potassium vaporization dust
emissions decrease since the main part of dust contains potassium
chloride KCl and potassium sulfate K2SO4 [24,27]. The addition of
kaolin supposedly causes a chemical effect in the ash with reactions
of kaolin and several ash components. It can be assumed that
calcium displaces potassium from its connection with silicon. With
increased calcium concentrations mass loss is increased; mainly
due to the release of potassium. Since kaolin helps to improve sintering
more than calcium does and because of the fact that calcium
leads to higher losses of potassium, calcium containing additives –
although wide in use [33–35] – cannot be recommended from this
point of view.