The study of the process of physic-chemical destruction of coal by the method of physical modeling

Abstract

One of the possible ways of physic-chemical destruction (PCD) of coal was considered. It is established that condition of the realization of a principle possibility of spontaneous dispersion of coal is to reduce its surface energy by 40-60 J/m2. Laboratory experiments to study the PCD of coal in different liquids were conducted. According to the results, kinetic curves of swelling coal in them transition D-G stamps is presents. It was established that the most intensive physical and chemical destruction of the coal to a particle size from tenths to tens of millimeters occurs in solutions of methylamine and hydrochloric acid. The most severe swelling of the coal was noted in those environment as well. The intensity of swelling is not significantly associated with the characteristics of wetting. The influence of various effects on the PCD parameters of coal was studied by physical simulation. The total time the chemical destruction of coal on the treated area was calculated. It was proposed method PCD for coals occurring in the clay rocks of various stages of catagenesis.

New technical solutions in the field of protection and fastening of mine workings

“…The scientific foundations of the technology of active management of the state of the rock mass have been developed at IGTM NASU. An analytical description of the stress-strain state of the rock mass near the working excavation [4,5,[12][13][14][15][16][17][18], including taking into account: free gas in the rocks, water saturation and man-made cracks [7,[19][20][21], geological disturbances [7], extreme deformation of rocks [4,5], physicochemical destruction of coal [22] is worked out by scientists of the institute. A model, which has been verified by numerous experiments in mines, has been developed.…”

Physical Simulation Test on Surrounding Rock Deformation of Roof Rockburst in Continuous Tunneling Roadway

“…At present, research into rockburst has mainly been conducted through indoor rock mechanics testing, numerical analysis, field monitoring, and physical simulation testing. Physical similarity simulation testing is a main and important laboratory experimental method to study the development, expansion, rockburst, and final failure of rock fractures [20,21]. Jiang Lishuai et al [22] have established two physical models utilizing similar materials and studied the influence of the advancing direction on the mining effect caused by a fault.…”

On Spontaneous Dispersion as a Cause of Microstratification of Metal Melts

“…The theory of spontaneous dispersion of solid metals upon contact with a metal melt in eutectic systems is considered in detail [14]. The conditions for spontaneous dispersion of coal were studied by the authors of [15], who believed that this is possible if the value of the specific free surface energy σm of the interface between solid and medium satisfies the Rebinder criterion [16]. This can be achieved by taking the size of coal particles in dispersion equal to the maximum size of particles that can participate in Brownian motion, which is δ = 5•10 -4 сm.…”

“…The first is the true spontaneous dispersion of particles of colloidal sizes, which leads to the formation of thermodynamically stable lyophilic systems that are prone to collective recrystallization. The second is the formation of coarse dispersions [15]. The thermodynamic condition for true spontaneous dispersion (entropic) is a decrease in the systemʹs free energy, which compensates for the increase in free surface energy during the formation of particles with a well-developed surface.…”

“…Kinetic calculations based on the mechanism of microcrack growth [26] demonstrate that, 𝝈 𝒎 𝒌 𝟏 𝝈 𝟎 / 𝟐 𝒌 𝟏 (20), where 𝝈 𝟎 is the specific surface energy of a body in a surface-inactive medium; k1 -coefficient determined by the geometry of microcracks and equal to 0.3-2.0. For example, for coals 𝝈 𝟎 𝟏𝟎 𝟐 Дж м 𝟐 [6], 𝝈 𝒎 𝟏𝟑 𝟔𝟎 Дж м 𝟐 [15]. Pertsov A.V.…”