Erosion characteristic of slope sandstone soaking in acid mine drainage

Abstract

Acid mine drainage(AMD) is one of the main reasons of slope instability in chemical mines with high sulfide. The pH values of the solution inside the mining pit decrease with the increasing of distance from ore body and vary from 1.2 to 4.6, according to the results of the water environmental investigation and the composition test of the slope sandstone in Xinqiao Pyrite Mine. Comparative experiments between original sandstone and AMD eroded sandstone samples show that after AMD erosion the uniaxial compressive strength and elastic modulus decrease by 30%−50% and 25%−45%, respectively, the cohesion and internal friction angle decrease obviously, and the Poisson ratio fluctuates between 0.20−0.29. The greater joints development, the higher residual stress after peak value, and the longer time to damage. Besides above, the reaction mechanism analysis of AMD eroded sandstone shows that the fillings in joints and fissures of sandstone are frequently decomposed and polyreacted, resulting in changes of interior molecule structure and framework composition, and decreases of cohesion and angle of internal friction between rock structure interfaces.

Research on Mass Transfer Process of AMD Corrosion Reaction and Model of Deposition Calculation for Acid Load

“…According to microcosmic chemical mass transfer principle, the dissolved minerals flux caused by ion exchange can be expressed by fluid velocity of pore rocks [7] and AMD solution concentration as…”

“…where 1 γ , 2 γ , 3 γ and 4 γ are reaction coefficients that can be acquired according to reaction temperature [9]. Thus, in the process of analyzing the load deposition of AMD corrosion, for simplifying the calculation, the influence of AMD corrosion on the slope body is evaluated by corrosion deposition rate by means of the measurement of PH variation.…”

Three‐Dimensional Reconstruction and Numerical Simulation Analysis of Acid‐Corroded Sandstone Based on CT

“…Acid erosion and a series of chemical reactions caused by it often led to the deterioration of coal, rock, support structure, etc. and induced serious safety accidents [6][7][8][9][10][11]. erefore, the research on the mechanical properties and failure mechanism of coal, rock, and structure under acid corrosion conditions has been widely concerned by scholars [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

“…Hutchinson et al [16] combined chemical experiments and SEM to study degradation laws of different forms of acidic substances on rock masses and discussed and established a corrosion theory based on chemical formulas and dissolution principles. Based on laboratory and field tests, Jiang et al [7] and Sracek et al [17] studied the macromechanical damage effects of the slope rock mass corroded by acid mine drainage (AMD). Taking calcareous sandstone and limestone as the objects, Han et al [18] and Wang et al [19] discussed the chemical corrosion mechanism from hydrochemistry through the erosion tests of different hydrochemical solutions.…”

Evaluation Approach of Rock Brittleness Index for Fracturing Acidizing Based on Energy Evolution Theory and Damage Constitutive Relation

“…Yao and Zhang [11] perform triaxial compression tests on limestone soaked in acidic solutions with different pH values and conclude that the deterioration level of the limestone strength increases with the decrement of pH value with the same saturated time and confining pressure. Jiang et al [12] find that the acid mine drainage can change the interior molecule structure and the framework composition, which degrades the cohesion and the angle of internal friction of the sandstone. Additionally, alterations of mortar mass [13] and longitudinal wave velocity [7,14] of rocks are also studied.…”