Leaching was applied in order to remove undesired phases and MgO after VCS or MCP. VCS products were leached in 1 or 5 M HCl/water solutions at room temperature for 15 h or 2.5 h, respectively. In some experiments, products were ball milled in ethanol medium before leaching for easier removal of side products. Wet ball milling was applied at 150 rpm for 7 h in a stainless steel jar with 50 pieces of 10 mm diameter stainless steel balls, in order to provide particle size reduction and liberation of side products. MCP products were leached in 1 M HCl/water solution for 30 min. In all leaching processes, slurry density (ratio of weight of the powder to be leached to the volume of the leach solution) was taken as 1/100 (g/ml).