Modelling of Aerodynamic Process for Coal Waste Dump Located in Geodynamically Dangerous Zone

2014

2011

2nd African Conference on Computational Mechanics (AfriCOMP11), University of Cape Town, Cape Town, 5-8 January 2011

The design of waste rock dumps in mining operations is usually based on mine planning and engineering criteria. However, there is an increasing concern on geochemical aspects. Therefore, a methodology to assess the geochemical evolution of future waste dumps is needed. This methodology typically relies upon numerical models. Such models should be flexible enough to allow the evaluation of different disposal concepts.

Rem: Revista Escola de Minas, 2012

In activities involving disposal of mine waste in a dump, it is necessary to carry out a preliminary study of the mechanical behavior of both dump and the foundation materials. Due to the complexity of this problem, numerical techniques are essential for providing an approximate answer to the problem. Thus, the finite element method (FEM) was used to evaluate the stress-strain-strength behavior of a hillside waste dump built on a deformable foundation by the ascending method; the results of which are herein presented. The dump material is considered to be Morh-Coulomb nonlinear elastic perfectly plastic while the foundation material is considered to be linear elastic. The numerical simulation of mine waste dump construction is carried out by the "gravity turn on" technique and the dynamic mesh procedure. Different geometric configurations are analyzed and it is concluded that some requirements established by law should be reviewed and refined.

Surface mining operation often results in removal of huge quantities of waste material and subsequently dumping it outside quarry areas or back filling in the excavated areas as the case may be. In recent years the unprecedented increase in the rate of accumulation of waste dumps has been a great environmental concern because this leads to more frequent large/small dump failures. General increase in environmental awareness has given rise to concern about safe and economic design of waste dump both during mining and following mine closure. On the one hand, stable slopes are essential for safety of men and machine and on the other hand vast amount of land and money can be saved by optimizing slope geometry of dump. It is therefore, a technical and economic necessity that the most efficient compromise be achieved, in the light of these two conflicting requirement; by optimizing the slope that is steep enough to be economically acceptable and flat enough to be safe. The intension has been to produce design graphs and tables covering wide range of each controlling parameter for mine planners and operators to select optimum slope geometry of waste dumps.

SN Applied Sciences

The management of overburden (OB) materials needs proper attention to safe mining operations. Several mine OB dump failures have been occurred due to inappropriate geotechnical and geometrical parameters. Increasing consumption of coal in thermal power plant also generates huge amount of ash which adversely affect the environment and its utilization is a great challenge. The present paper reviews the effect of fly ash on the different geotechnical properties and stability of coal mine OB dump material to explore a safe and effective utilization of fly ash. It was found that up to 30% fly ash can potentially modify the compaction characteristics, California bearing ratio value, unconfined compressive strength, and shear strength parameters of OB dump material. Based on the review, it may be suggested that fly ash-OB mix can be effectively utilized in the mine OB dump and for the mine haul road construction thus, provides an alternative mode of fly ash utilization in huge quantity.

Donghua Zhang, Naoya Inoue, Takashi Sasaoka, Hideki Shimada, Akihiro Hamanaka, Kikuo Matsui

Dumping areas represent a stable hazard. To clarify the formation mechanism of dumping piles on dumping area stability, an investigation in open pit mine was performed. Moreover, experiments with gravel were conducted based on the research site conditions. The geological conditions, dumping operation, and waste particle size distribution were investigated in the Heidaigou open pit mine. Particle size distribution, dumping height, dumping volume, and floor inclination were varied to examine their effects on a single pile formation. The design of blasting can be modified to make the particle size of waste smaller. The volume of the bucket does not have a pronounced effect on dumping pile repose angle, capacity of dumping pile, and dumping area stability. The smaller the floor inclination, the better it is. Two measures are proposed to increase the kinetic force of friction between waste material and floor surface. The interval distance, dumping volume and dumping height were also varied to examine the interaction between the formations of multiple piles. The dumping width should be decided through optimization efficiency of bulldozer and dumping device in bucket wheel excavator-belt-stacker dumping operation and dragline dumping operation. Moreover, the volume of the bucket does not have a pronounced interaction effect. In the dumping operation, the work amount of bulldozer decreases as dumping pile increases. The design of the dumping operation must consider the total efficiency of ground leveling operation and forming dumping the area.

To predict the spontaneous heating of coal pile by computational fluid dynamics (CFD) is very meaningful for preventing the coal pile from self-ignition. A two-dimensional (2-D) numerical model, which could be simply implemented in FLUENT, was developed in this study. The chemical kinetic parameters of low-temperature oxidation of coal, which were expressed by the outer surface area of particles, were well measured in experiments. The coal piles under different conditions were calculated by using the developed model and measured kinetic parameters, in order to make clear the effects of some important factors. The simulation results indicated the evaporation of moisture from coal played a critical role. The pile height, coal type, wind velocity, and heat loss from bottom have significant effects on the process of spontaneous heating of coal pile. According to these effects, in order to increase the heat loss of pile and then effectively inhibit the self-ignition, the low pile height, good ventilation surrounding the pile, and ground material with high thermal conductivity below the pile should be used. The model developed in this model is expected to become a reliable tool to predict the spontaneous heating of coal pile.

Journal of The Institution of Engineers (India): Series D, 2021

The depths of open-pit mines have been increasing in the last few decades. This transformation generates a vast amount of waste rock material per unit mining area imposing a significant economic, social and environmental liability on the mine operators. The scarcity of dumping land along with the rise in population, competing urbanization and associated environmental clearance problems require accommodating this ever-growing volume of waste rock material at restricted available space. On the contrary, the frequency of accidents due to the instability of the waste dump slope structures has also increased, resulting in significant fatalities, apart from the economic, social and environmental impacts of these disasters. Numerous scientific studies have been conducted to reduce the occurrence of such incidents. This paper conducts a critical review of the numerical modelling-based stability analysis of such waste dump slope structures. The popularly cited cases of dump slope instability have been analysed to synthesize pertinent findings regarding the approach of stability analysis, broader design criteria, and optimization. The critical parameters to numerical modelling-based design of a safe dump slope structure are discussed in detail. The significant output parameters, apart from the factor of safety, are also outlined for evaluating the state of stability.

Journal of Sustainable Mining

Precipitation, especially with a high intensity, affects the condition of mining waste dumps. The article presents the results of research aimed at determining the impact of rain on water erosion on the slopes of a coal waste dump and its thermal state. Preliminary tests of the condition of two slopes of the coal waste dump in Libią _ z (Poland) undertaken in the frameworks of the TEXMIN project was carried out using modern geodesy techniques (low-ceiling photogrammetry and TLS terrestrial laser scanning). The current geometry of the slope surface was faithfully reproduced in the form of a cloud of points with known coordinates x, y, z. The thermal state within the analyzed slopes of the dump was also assessed. Based on thermography studies and measurements of temperature and gas concentrations inside the object, two zones of thermal activity were located on one of the examined slopes. The test results constitute the initial state against which the results of further tests will be compared. This will allow to determine the influence of precipitation on the amount of water erosion and the thermal state of the dump in a specific time period.