Journal of Mines, Metals and Fuels

A Review on Tool Life in Coal Measures Rocks

Satya Prakash — 2024-03-29

Tungsten carbide inserts in rock drill bits are predominantly used in drilling rocks, particularly in mining industries. The research studies performed on drill bits have been limited to several factors such as collecting failure data of bit components from the field, conducting wear tests considering rock properties, and introducing new coated insert materials. The role of Artificial Intelligence (AI) and Machine Learning (ML) for the betterment of tool wear with real-time data is limited. The present study has offered an evaluative perspective of an essential industrial issue. In this review, a concept map presents a visual organization and representation of knowledge obtained during the study. Utilizing the propositions from the concept map, a brief review of the integrated concepts of researchers relating drill bits, failure data, numerical and statistical models, wear analysis, reliability assessment, and prerequisites in developing new materials have been discussed in the backdrop of the present study.

Investigation and Optimization on Parameters of Gas Additive Powder Mixed Near Dry –EDM (GAPMNDEDM) by using Taguchi based- Grey Relational Optimization

Ajit — 2024-03-29

The Gas Additive Powder Mix near Dry Electric Discharge Machining (GAPMND-EDM) serves a manufacturing purpose, specifically for cutting hard materials. This involves the removal of material from a workpiece via fusion, ablation, and evaporation caused by the heat energy generated through electric sparks during energy supply. The process offers several advantages in terms of performance and characteristics. This research project aims to optimize key process parameters, including material removal rate, surface roughness, residual stresses, and microhardness. The study employs a methodology that combines the standard deviation-based objective weighting method with GRA (Gray Relational Analysis) optimization to enhance the hybrid GAPMND-EDM process when applied to EN-31 material. Experimental runs were conducted to evaluate the impact of various input factors, such as pulse-on time, discharge current, dielectric fluid pressure, and metallic powder concentration. The taguchi-based GRA method was utilized for this purpose, and the experimental design followed an L-27 orthogonal array with the assistance of Minitab-19 software. A total of 27 experiments were performed, encompassing diverse combinations of process parameters. Subsequently, an ANOVA (Analysis of Variance) was executed to analyze the influence of pulse-on time, discharge current, dielectric fluid pressure, and metallic powder concentration on Material Removal Rate (MRR), Surface Roughness (SR), Residual Stress (RS), and Microhardness (MH). The result shows the optimal combination of parameters, denoted as A2B2C2D1, was identified as the preferred configuration.

Numerical Solution of Micropolar Fluid for Jenkins Model with Micro-Rotation between Two Rotating Disks

G. R. Meghashree — 2024-03-29

The flow of a steady, axi-symmetric, incompressible micropolar fluid between two infinite rotating disks is described for Jenkins Model. The governing equations are reduced to non-linear ordinary differential equations and are solved numerically through the shooting technique. The graphs are plotted and the impact of the material constant is analysed on the velocity, micro-rotation velocity profiles and pressure. The results reveal that the material constant has a significant effect on radial velocity, axial velocity and pressure.

Effect of Metal Nanoparticles in the Field Emission of Silicon Nanowires

Karanam Madhavi — 2024-03-29

In this work, an efficient method is reported for creating a metal nanoparticle (silver) / Si composite structure consisting of a vertical array of silicon nanowires (SiNWs) decorated with silver metal nanoparticles. A two-stage metal-assisted etching method is employed to obtain SiNWs and Silver (Ag) metal nanoparticles are decorated on the SiNWs using the electroless deposition method. It allows the good coverage of silver metal nanoparticles over SiNWs. Scanning Electron Microscopy (SEM) analysis revealed that Ag was covered with SiNWs. High-work function metal nanoparticles such as Ag nanoparticles on SiNWs have been utilized in different applications such as photovoltaics and sensors. The size of SiNWs is determined through the Raman shift. The silicon optical phonon peak showed an increase in redshift and a decrease of full-width at half maxima with a decrease in diameter due to the quantum confinement. The Electron Field Emission (EFE) characteristics of the Agdecorated SiNW films were studied based on the current-voltage measurements and analyzed using the Fowler-Nordheim (F-N) equation. The low turn-on field is obtained through the Ag metal nanoparticles which have wider applications in lowpower operational devices.

Influence of Structural Discontinuity on Slope Stability using Numerical Modelling and Sirovision

S. Raja — 2024-03-29

The rock mass consists of heterogeneous and anisotropic materials, with smaller and larger blocks of rock, and the presence of structural discontinuities is a significant concern. Characterising the rock mass is crucial for the success of engineering excavations in such areas. A detailed study of joints, their orientation, and discontinuities in the exposed rock mass is crucial as they greatly influence stability and fragmentation. Existing rock mass classifications like Rock Mass Rating (RMR) and Q-classification require various geological parameters and physico-mechanical properties of the rock. However, determining these parameters conventionally can be time-consuming, requiring careful on-site measurements. The number of opencast coal mines is increasing compared to underground mines due to shorter gestation periods, higher productivity, and quicker returns. However, opencast mining raises environmental concerns such as air and water pollution, solid waste management, land degradation, and socio-economic issues. Additionally, many opencast coal mines, regardless of size, are reaching greater depths, making analysing bench slopes and ultimate pit slope design crucial. Slope failure in these mines leads to production loss, additional costs for recovery and handling of failed material, pit dewatering, sometimes mine abandonment or premature closure, and loss of life. A study was conducted at Prakash Khani Opencast Mine – IV, Manuguru area, M/s The Singereni Company Collieries Limited (SCCL), to investigate the influence of structural discontinuities on slope stability. SIROVISION software was used to assess rock mass characterisation, while PLAXIS-2D software was employed to analyse the influence of structural discontinuities on slope stability. A comparative conclusion was drawn based on the results obtained from SIROVISION and PLAXIS-2D analyses. The study revealed that the RMR of the mine ranged from very poor to fair due to numerous discontinuities. It was also found that discontinuities in the slope decrease the Factor of Safety (FOS), indicating an impact on slope stability.

Numerical Investigation into Factors Affecting Stability of Opencast Coal Mine's Rise Side Highwall Slope

Ch. Venkat Ramana — 2024-03-29

Open-pit coal mining accounts for 93% of India's total coal production, playing a significant role in meeting the nation's substantial energy needs. The success of an open-pit mine hinges on maintaining the steepest and deepest slopes that remain stable over the mine's lifespan. However, slope failure is a complex issue influenced by numerous factors. In the context of openpit coal mines, the rise side highwall involves cutting through a rock mass containing various elements like an unconsolidated weathered mantle of sandstone, sandy clay, clay, carbonaceous shale and coal. Some opencast mines within the Godavari Valley Coal Field (GVCF), India have encountered significant pit slope failures. This paper uses a numerical modelling approach aimed at effectively assessing the stability of the rise side highwall, leveraging available geotechnical data from one of GVCF's largest opencast coal mines. The research investigates the impact of seven detrimental factors on slope stability, including dynamic loading due to blasting, employing a methodical One-Factor-At-A-Time (OFAT) approach. The study utilises Rocscience Phase2 version 9.0, a Finite Element Method (FEM) based numerical modelling software to gauge the sensitivity of each factor on the Factor of Safety (FoS). The numerical modelling results indicate that there is a linear decrease in FoS corresponding to the reduction in cohesion and an exponential increase in the FoS as the angle of internal friction rises. Furthermore, the analysis reveals significant impacts on the FoS due to groundwater and seismic loading from the blasting. This approach aims to comprehensively analyse and understand the intricacies of slope stability in the specific context of open-pit coal mining.

Slope Monitoring Techniques in Opencast Mines: A Review of Recent Advances

Vinay Kumar Singh — 2024-03-29

The process of excavating rock mass induces changes in the stress distribution within the slope, rendering it prone to deformation over a specific duration. The potential consequence of movements along the weak planes is the ultimate breakdown of the slope. Various monitoring techniques, including visual inspection, laser scanning, Lidar scanning, total stations, Global Positioning Systems (GPS), state-of-the-art radar scanning, and micro-seismic monitoring, are currently employed in mining environments to forecast slope failure and deformation rate. This article will discuss the need to implement a continuous slope monitoring system, including categorizing such systems and an overview of the current state of existing slope monitoring technologies. The paper also discusses the applications of UAVs (Unmanned Aerial Vehicles) in slope monitoring. The research proposes implementing a consistent and continuous slope monitoring strategy grounded on empirical data when planning big and deep opencast mines. This approach is crucial for guaranteeing optimal safety measures and enhanced productivity levels.