Mineral Processing
Mehrshad Asghari; Mohammad Noaparast; Mohammad Jahani Chegeni
Abstract
Because roller screens are connected to the pelletizing discs on one side and the green iron ore induration furnaces on the other side in pelletizing plants, they play a crucial role in the plant's productivity and steel production process. Consequently, an optimal performance and structural design are ...
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Because roller screens are connected to the pelletizing discs on one side and the green iron ore induration furnaces on the other side in pelletizing plants, they play a crucial role in the plant's productivity and steel production process. Consequently, an optimal performance and structural design are essential in this context. A significant issue with roller screens during the classification of green pellets is the deformation of the rolls caused by the force exerted by the pellets during operation. This deformation disrupts the uniformity of the gap between the rolls, thereby reducing the efficiency of the screen, and the overall performance of the circuit, as well. Despite the importance of this issue, no studies have been conducted to investigate the force exerted by the pellets during classification on the screen or the subsequent mechanical behavior of the rolls. Therefore, this study employs the discrete element method–finite element method (DEM-FEM) coupling simulation technique to examine, for the first time, the mechanical behavior of rolls and to optimize their structural design. The results indicated that decreasing the roll diameter from 80 mm to 30 mm led to 1088 times increase in the average total deformation of the rolls. Furthermore, increasing the thickness of the polyurethane liner from 3 mm to 14 mm caused the average total deformation to rise by 54 times.
Mineral Processing
Rahul Shakya; Manendra Singh
Abstract
Due to the critical nature of seismic risk in metro tunnels, the seismic response of underground tunnels is a highly delicate topic. The seismic response of a sub-surface structure depends more on the properties of the surrounding ground and the induced earth deformation during an earthquake than on ...
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Due to the critical nature of seismic risk in metro tunnels, the seismic response of underground tunnels is a highly delicate topic. The seismic response of a sub-surface structure depends more on the properties of the surrounding ground and the induced earth deformation during an earthquake than on the structure's inertial properties. This paper examines the seismic response of a typical section of the underground tunnel of Delhi Metro Rail Corporation (DMRC) between Rajiv Square and Patel Square in New Delhi's Connaught Place. Three-dimensional elasto-plastic analysis of Delhi metro underground tunnels under the seismic loading has been performed by finite element method using the Plaxis 3D software. Additionally, the influence of various boundary conditions on the dynamic response of metro tunnels has been examined. A comparison of the three-dimensional analysis with the two-dimensional plane-strain analysis has also been made. Horizontal displacements were experienced maximum compared to the longitudinal and vertical displacements in the soil-tunnel system. In dynamic analysis, the absorbent boundary is much more effective in controlling the displacements and the induced acceleration than the elementary boundary or the free-field boundary.
Rock Mechanics
Mounius Bashir; Manendra Singh; Krishna Kotiyal
Abstract
Among all methods for ground improvement, stone columns have become more popular recently, owing to their simple construction and plentiful availability of raw materials. However, in relatively softer soils, ordinary stone columns (OSCs) experience significant bulging owing to the minimal confinement ...
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Among all methods for ground improvement, stone columns have become more popular recently, owing to their simple construction and plentiful availability of raw materials. However, in relatively softer soils, ordinary stone columns (OSCs) experience significant bulging owing to the minimal confinement offered by the surrounding soil. This necessitates the introduction of reinforcements in the stone column, to enhance their strength in such circumstances. The subject of this investigation was the assessment of the behavior of horizontally reinforced stone columns (HRSCs), introduced in layered soil, under the raft foundation. The soil material included was idealised using an isotropic linearly elastic fully plastic model with a Mohr-Coulomb failure criterion. There are a total of six separate factors required by the Mohr-Coulomb criterion. These include cohesion (c), the soil's dry unit weight (γd), the Poisson ratio (μ), the angle of internal friction (φ), the angle of dilatancy (ψ), and the Young's modulus of elasticity (E). At the very beginning, the load-settlement response of unreinforced soil was evaluated followed by a comparative study between square and triangular arrangements of stone columns, at different spacings, under the raft, to arrive at the configuration that encounters minimal settlements and lateral deformations. Furthermore, circular discs of suitable geogrid material were introduced along the length of the stone column. The elastic behaviour of geogrids is governed by two properties: tensile modulus and yield strength. The load-settlement behavior and lateral deformations of the resulting reinforced stone columns, with OSCs were compared. Furthermore, the spacing between the circular discs of geogrids was kept at D/2, D, 2D, and 3D, where D is the diameter of the stone column. According to the findings of an investigation conducted using FEM software, the performance of a granular pile group that is laid out in the shape of a triangle encounters much less lateral deformation and settlement than the square arrangement. The results also show that the performance of HRSCs was way better than those of OSCs, under the same in-situ soil conditions.
A. Ghasemloonia; S. D. Butt
Abstract
Underground caverns in rock salt deposits are the most secure disposal method and a type of gas-storing facility. Gas storage plays a vital role in ensuring that a strategic relationship is secured between an established energy infrastructure provider and a midstream energy company. The Fischells Brook ...
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Underground caverns in rock salt deposits are the most secure disposal method and a type of gas-storing facility. Gas storage plays a vital role in ensuring that a strategic relationship is secured between an established energy infrastructure provider and a midstream energy company. The Fischells Brook area is a pillow-shaped body of salts located in the St. George's Bay area of southwest Newfoundland, which has three layers of salt beds, and is capable of excavating caverns for the storage purposes. The development of cavern facilities requires the stability analysis through numerical models and experimental facilities. This work was motivated to examine the engineering feasibility of the salt cavern characteristics in this area, and to investigate its stability under creep behavior. An experimental test facility was developed to investigate the constitutive parameters governing the creep of rock salt, and the constitutive parameters were implemented into a developed finite element model to investigate the stability of the cavern over a 5-year period. Also a stress-based dilatancy failure envelope was developed to interpret the results of the numerical model, and to conduct sensitivity analyses for different design scenarios. The design recommendations developed in this study will be implemented as a key part of an engineering feasibility study for underground caverns in salt deposits in western Newfoundland.