Measuring conductivity by adding acid is not expedient. Figure shows the temporal change of conductivity for the investigated particle systems at a time interval of 1 min. Acid is added after 60 min. A sudden increase in conductivity can be seen when the acid is added, which then remains constant. In the case of talc in particular, leaching is not yet complete according to Figure , which cannot be read from the conductivity. The change in ion concentration can therefore not be estimated from the conductivity. However, the fluctuating values in the conductivity, which are due to foaming of the suspension, are striking. Without the addition of acid, the ion concentration can be estimated via the conductivity, as this increases via free ions in the solution. Table shows the measured ion concentrations of Ca 2+ and Mg 2+ in the ion chromatography after one minute in deionized water and after 60 minutes in deionized water. After the addition of acid, a measured value was recorded again after a further 60 min. For Anhydrite the Ca 2+ concentration is 14-times higher than for Talc. Regarding the Mg 2+ concentration Talc has a 2.7-times higher concentration than Anhydrite. These changes can not be seen with measuring the conductivity of the suspension. When looking at the leaching of Ca and Mg from both minerals, Figure shows a difference between the two alkaline earth metals. While calcium is in the stationary end range after 30 min, the leaching of magnesium is not yet complete after 24 h. As both minerals are relevant, the further leaching time was set at 3 h. Therefore, the following experiments are carried out to investigate the influence of mass at a leaching time of 3 h. Figure shows the influence of the particle mass concentration on the leaching quality. Noticeable are the values of 𝐶 𝐶𝑎,𝑇𝑎𝑙𝑐 * and 𝐶 𝑀𝑔,𝐴𝑛ℎ𝑦𝑑𝑟𝑖𝑡𝑒 * which are both above the value of 1. This is chemical not possible, because it means a higher ion content in the solution than the ion content of the added particles. The only explanation is the LOI, which is 1 % of the particle mass for anhydrite and 5 % for talc, see Table . These components must include both calcium and magnesium. The high loss on ignition (LOI) content of talc is reflected in the Ca 2+ values, which are up to 1.5 times the theoretical amount of calcium. In the case of anhydrite, the Mg 2+ values are only above 100% at St = 1, but this corresponds to only 3 hours of leaching. After 24 hours of leaching, all measured values are 𝐶 𝑀𝑔,𝐴𝑛ℎ𝑦𝑑𝑟𝑖𝑡𝑒 * > 1, which is only possible due to trace elements in the organic residues. The exact proportion of calcium and magnesium from the trace elements cannot be determined with the method described here.