Characteristics of deep Ordovician limestone water and its concentrated application in Ordovician limestone water disaster prevention

In order to reduce mine water discharge and floor grouting cost, taking floor grouting material modified by deep Ordovician limestone gushing water as an example, the conventional ion, suspended matter and trace element in the mine water had been tested.Variation characteristic of mine water quality with heating concentration had studied, then the comparison tests on the water and mechanical properties of clay grout and cement grout modified by mine water had been conducted.And the grouting engineering of mining face had been designed and constructed by the modified loess margin of expansion.The results show that mine water in deep coal area are characterized with high salinity, rich suspended matter, limited special material and high permanent hardness.After the mine water is concentrated, it is beneficial to the enrichment of Ca²⁺, SO₄^2-, Cl^-, etc.and the concentration of HCO₃, which go against modified slurry, is decreasing. However, the double electrode layer of clay slurry modified by concentrated mine water flocculate, so the compressive strength of clay sample increases and the permeability of clay sample reduces.Initial setting time of cement paste modified by concentrated mine water is short, and the modified cement samples after 1 d, 3 d, 28 d improve com-pressive strength by 1.7-3.3, 5.3-7.7, 8.3-17.1 MPa respectively. Modified loess margin of expansion increases 19.5%, and the applied coal working face had been mined safely with the grouting quantity reduction by 16%.