Abstract
With the gradual depletion of surface and shallow mineral resources, deep mining has become the trend of future mining development. In the process of deep mining, the temperature will increase with the increase of mining depth, and will have a significant impact on the hydration reaction rate and products of the backfill, thus changing the physical and mechanical properties of the backfill and affecting the stability of the backfill in the underground stope. In this study, the unclassified tailings of a gold mine and ordinary Portland cement were used as filling materials. By means of nuclear magnetic resonance (NMR) analysis, scanning electron microscope (SEM) observation, uniaxial compression experiment and theoretical analysis, the characteristics in the early curing stage of the unclassified tailings backfill slurry under high temperature conditions and the evolution strength rules of the backfill were explored. The results show that the increase of temperature leads to the decrease of porosity in the backfill slurry, the decrease of free water content, and the increase of adsorbed water and pore water content. Increasing the curing tem-perature can increase the degree of hydration reaction, so that the hydration products of the backfill form a denser structure, which eventually leads to the increase of the strength of the backfill. The research results have important theoretical significance for the strength design of backfill in deep mining.