“…Two fractions were used with the following mean grain diameter (d 50 ): 10.87 μm and 29.14 μm. The results for a fraction of 25.19 μm, which was an integral part of these tests, the authors published before [8]. Modifying the surface of calcite was carried out by stearic acid CH 3 (CH 2 ) 16 COOH -content of stearic acid: 0.3; 0.5; 0.8; 0.9; 1; 2; 2.5; 3 and 4%.…”