JOURNAL OF GEOMINE
Year:2023 | Volume:1 | Issue:2|Papers Count:6

Coal has been used for centuries as a energy source, and it remains a vital fuel for electricity generation in many countries. However, the risks of coal mining are high, and outbursts and gas emissions are two significant hazards associated with underground coal mining. Coal and gas outbursts are sudden and violent ejections of coal, gas, and rock from the working face of an underground coal mine. They occur when high gas levels, such as methane, accumulate in the coal seam and are released rapidly due to the stress and pressure caused by mining activities. Numerical simulation is one of the most powerful methods to study this complex phenomenon. The purpose of this article is to investigate the effect of coal strength parameters on the occurrence of the desired phenomenon in underground coal mines using the finite element numerical method. For the study, the sub-tunnel of the E4 workshop of the Parvade 1 Mine of Tabas, which is located at a depth of 472 meters from the ground, was investigated in the Phase2 simulation software and the possibility of an outburst in this layer assuming the existence of a pocket with a pressure of 0.6 MPa and crushed rock. The unstable failure index has been used to determine outburst-prone areas. In general, the application of UFI is to detect areas prone to brittle failure in phenomena such as Spalling, Rockburt, and Outburst. When this index is greater than 1, there is a possibility of this phenomenon because there is excess energy in the rock. According to the results of this research, strength parameters such as cohesion, angle of internal friction, and modulus of elasticity have a significant effect on the severity of outburst, at the same time the probability of this phenomenon is estimated independently of the tensile strength of coal. Considering that the UFI index used confirmed the results of previous researchers about this phenomenon, it can help predict this phenomenon. For the first time, this criterion is written based on energy components instead of stress and was able to show the effect of different parameters on outbursts.

The study area is a part of the Sistan suture zone of eastern Iran that is located in the southwest of Qayen city with a northwest-southeast extension. The studied rocks were affected by the regional metamorphism with low to high metamorphism intensity variables. This metamorphism has produced greenschist, amphibolite, and granulite facies rocks. Mineral chemistries indicate that amphiboles of the studied metamorphic rocks were magnesiohornblende and are categorized as metamorphic amphiboles. Pyroxenes are of Augite type, plagioclases are at the level of andesine to labradorite, and biotites are of types that are rich in iron. Definite chemical zoning of garnets in studied metamorphic rocks of the area is the indicator of their formation and development during increasing pressure and temperature that is evidence of Subduction and the rise of a part of the metamorphic rocks during thrust faulting in a direction opposite to that of Subduction in the study area.

Loading equipment is one of the most essential equipment in open-pit mining operations. Any failure of all or some of these equipment leads to a decrease in the production and profitability of the mine. Trucks are one of the well-known machines applied for mineral transportation. The occurrence of any kind of failure in trucks leads to the stop of the loading operation and, finally the complete stop of the mining operation. Knowing the operating conditions of the mineral transport unit is one of the critical parameters to prevent unwanted stops and accordingly improve the operational performance of the equipment. Therefore, it is necessary to check the reliability and maintainability of loading machines to provide a maintenance and repair program and control the productivity of mineral transportation operations. In this paper, the reliability of seven trucks in Sungun Copper Mine, Iran, was evaluated and discussed. To achieve this, the statistical approach was used to obtain the best reliability function, and then the reliability-based preventive maintenance scheduling was proposed. The results of this paper showed that the reliability of the fleet of mining trucks decreased to 80% in 47 hours and reached zero after about 300 hours. The results of this study are helpful for mine managers and contractors to have a safe and reliable mineral transportation system.

The application of high-pressure grinding rolls (HPGR) in iron ore processing is expanding. However, to maximize their utilization, it is crucial to understand the impact of various parameters on their operation, given their advanced technology. Wear is an essential factor that needs to be considered when operating these mills. Failure to manage wear can lead to substantial costs and a decline in machine efficiency, as well as the efficiency of the comminution circuit. Therefore, it is imperative to control the wear rate of rolls by adjusting the machine accordingly. This research aims to measure the wear pattern of HPGR rolls in the primary grinding circuit of the Sanabad Iron Beneficiation Plant in Iran. The results indicated that the wear rate of the studs along the rolls was not uniform but rather concave, and the maximum wear rate was observed in the central part of the rolls. The wear rate of the studs on the fixed roll was higher than that of the floating roll. For the current mill, the predicted useful life of the rolls was estimated to be between 12000-13000 hours, considering the operating time of 8000 hours of the current HPGR.

The successful implementation of the GSI system in numerous global construction projects has proven its capability in giving accurate estimations of the strength of diverse rock formations. The patterned arrangement of GSI values in open-pit mining corresponds to the occurrence of geological rifts. The utilization of geostatistical techniques is effective in comprehending the spread of regionalized factors in each designated research location. Because GSI is a non-additive variable, it may be more beneficial to simulate than estimate it. This is because simulation algorithms can provide results without smoothing. In this work, the theory of regionalized variables was used to analyze and interpret the spatial distribution of GSI values measured at the Gol-Gohar iron mine southeast of Kerman City in Kerman Province, southeastern Iran. Variographic techniques were used to understand and identify the regional behavior and distribution of GSI measurements. Moreover, it is feasible to model the GSI estimations for individual blocks on the pit wall and generate maps to decipher the performance of the localized factors. Such assessments can aid in devising strategies for enhancing the slope stability of pit walls to a maximum extent.

Nanoclay, composed of phyllosilicates, exhibits unique properties due to its layered structure and its ability to swell or shrink in response to water accumulation or withdrawal. Its use in geostability involves enhancing the geotechnical properties of soils, such as reducing the plasticity index, increasing specific gravity, improving compaction, and enhancing shear strength. Additionally, nanoclay serves as a reinforcing material in polymer composites, improving their strength, toughness, durability, and barrier properties. This study provides an overview of the properties, applications, and challenges associated with nanoclay in soil stabilization. The compatibility of nanoclay with organic monomers and polymers can be modified to enhance the overall performance of nanocomposite materials. Various industries and applications utilize nanoclay for soil stabilization, including construction, agriculture, mining, and environmental remediation. However, there are challenges associated with its use, such as cost, compatibility with different soil types and stabilizers, environmental concerns, long-term durability, and health and safety risks. Future research should focus on the synthesis, characterization, and surface modification of nanoclay, as well as the effectiveness of different soil stabilization methods and potential environmental impacts.