Static method of rock destruction with using a non-explosive destructive mixture

Abstract

The authors developed a mathematical model of the location of boreholes when using a non-explosive destructive mixture (NDM), which contributes to the formation of a continuous line of cracks and the smooth separation of rocks in the massif. The dependences of the change in the effective distance between contour holes on their diameter, compressive stress at the hole wall, Poisson's ratio, the tensile strength of the rock, and the additional stress directed at moving the block walls and opening them when using the NDM are established. A series of experiments on finding an optimum compounding of structure of NDM which would allow to accelerate process of hydration without additional heat release and to provide high pressure during 5-8 h after use of structure was carried out. Variants of the chemical mixture that maximizes the expansion and destruction of rocks were optimized. More than 200 experiments on rupture of samples of various materials (glass bubbles, plaster, brick, marble) were conducted. On the basis of the received results, a method was developed for formulating composition of NDM with using components from local raw materials, which is safe for storage, transportation and use, creates high internal pressure in the holes and contributes to static destruction and rupture of rocks. The method for separating monoliths from the massif with use of new composition of the NDM is also developed. Implementation of the proposed method allows to displace a block of monolith into the goaf of the pit under the influence of high pressure of self-expansion with no spontaneous outburst of mixture. Experimental-industrial tests of the proposed composition and method of the NDM production were carried out in the Nuratinsky marble deposit of the Navoi region. As compared with the drilling and blasting method, method of separation of monoliths from massif by using the new composition of NDM makes it possible to reduce labour intensity of performed works, provides protection of environment, reduces cost of production and energy intensity of mining works, as well as increases safety of their execution Keywords: mathematical model of the location of holes, non-explosive destructive mixture, formation of continuous line of cracks, high internal pressure in the holes.