cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.7899806.v1
title: Depth effect on sandstone strength properties

description: Abstract The present article focuses on the study of different physical-mechanical parameters; it presents the results of a preliminary investigation aimed at experimental characterization. To simulate the mechanical behavior of the rock, a reference material needs to be chosen. The reference material selected is Sandstone, which is commonly used in this field of study. The behavior of sandstone from the region of Hassi Messaoud, which is well known for its petroleum operations, deals mainly with different mechanical sandstone properties and their varying strengths. The relationships between different depths and both of the mechanical sandstone properties were evaluated. As a result, useful relationships were found for different depths and the following properties: uniaxial compressive and triaxial test, Young's modulus and Poisson ratio.
DOI: 10.6084/m9.figshare.8324603
title: Typological analysis of slidequakes emitted from landslides: experiments on an expander body pile and Sobradinho landslide (Brasilia, Brazil)

description: Abstract Reactivation of a landslide is usually accompanied by microseismic signals emitted from the deforming soil mass. The reproduction of similar signals in a physical model test conducted under control conditions can allow researchers to explore and test such complicated signals to improve the prediction of full-scale failure. The present study investigates the similarity between the slidequakes (microseismicity) naturally emitted from an existing colluvial landslide (Sobradinho, Brazil) in response to rainfalls and the emissions generated by a pullout test of an expander body (EB) pile in tropical soil under controlled conditions. The microseismic signals emitted from both experimental sites (i.e. the landslide and the EB pile test) were recorded and compared. Data were acquired by mini-arrays of four short-period seismometers. For the signal nomenclature, a typological scheme was adopted, in which sonograms/spectral contents of the signals were used. As a result, short duration microseismic signals were observed during the pullout test. In contrast, at the Sobradinho landslide, the testing detected signals of different characteristics whose source mechanisms have remained ambiguous, mainly because of the short duration of the data campaigns. However, at the landslide, propagating events were observed that might be attributed to the energies generated by the river bedload during the heavy rains. The present study offers some insight into the pre-collapse dynamic behavior of unstable slopes in clayey formations.
DOI: 10.6084/m9.figshare.8324603.v1
title: Typological analysis of slidequakes emitted from landslides: experiments on an expander body pile and Sobradinho landslide (Brasilia, Brazil)

description: Abstract Reactivation of a landslide is usually accompanied by microseismic signals emitted from the deforming soil mass. The reproduction of similar signals in a physical model test conducted under control conditions can allow researchers to explore and test such complicated signals to improve the prediction of full-scale failure. The present study investigates the similarity between the slidequakes (microseismicity) naturally emitted from an existing colluvial landslide (Sobradinho, Brazil) in response to rainfalls and the emissions generated by a pullout test of an expander body (EB) pile in tropical soil under controlled conditions. The microseismic signals emitted from both experimental sites (i.e. the landslide and the EB pile test) were recorded and compared. Data were acquired by mini-arrays of four short-period seismometers. For the signal nomenclature, a typological scheme was adopted, in which sonograms/spectral contents of the signals were used. As a result, short duration microseismic signals were observed during the pullout test. In contrast, at the Sobradinho landslide, the testing detected signals of different characteristics whose source mechanisms have remained ambiguous, mainly because of the short duration of the data campaigns. However, at the landslide, propagating events were observed that might be attributed to the energies generated by the river bedload during the heavy rains. The present study offers some insight into the pre-collapse dynamic behavior of unstable slopes in clayey formations.
DOI: 10.6084/m9.figshare.8324507
title: Analysis of the densification of a composite obtained by sintering process of aluminum bronze powders with different carbides

description: Abstract Aluminum bronze alloy is applied in environments that require materials of high mechanical resistance and wear, such as marine, oil & gas and aerospace ones. This study analyzes the densification of composites based on aluminum bronze with additions of the vanadium (VC) and niobium (NbC) carbides, and the influence of these carbides in the milling efficiency and improvement of the diffusion process between particles to obtain better results for density and porosity. The composites were produced by powder metallurgy from aluminum bronze powders obtained from the mechanical milling process of discarded scraps. The efficiency of the sintering process depends on parameters, such as the time and temperature of sintering, together with the size of the particles obtained from the milling process. This study aimed to obtain and characterize the composites produced by the powder metallurgy route, with NbC and VC addition and to analyze physical properties, such as density and porosity. The powder morphologies, particle sizes and samples sintered were performed by scanning electron microscopy (SEM), X ray diffraction (XRD), laser diffraction analysis and optical microscopy (OM). The results indicate that addition of VC improves the milling efficiency, when compared to NbC addition, since it promotes a greater reduction of the particle size, directly favoring the sintering process. In this case, to achieve similar particle size, twice the milling time was required when NbC was used. The density values achieve ~ 73% of reference material for VC addition and ~ 68% for NbC and porosities varying between 27% and 38%.
DOI: 10.6084/m9.figshare.8324507.v1
title: Analysis of the densification of a composite obtained by sintering process of aluminum bronze powders with different carbides

description: Abstract Aluminum bronze alloy is applied in environments that require materials of high mechanical resistance and wear, such as marine, oil & gas and aerospace ones. This study analyzes the densification of composites based on aluminum bronze with additions of the vanadium (VC) and niobium (NbC) carbides, and the influence of these carbides in the milling efficiency and improvement of the diffusion process between particles to obtain better results for density and porosity. The composites were produced by powder metallurgy from aluminum bronze powders obtained from the mechanical milling process of discarded scraps. The efficiency of the sintering process depends on parameters, such as the time and temperature of sintering, together with the size of the particles obtained from the milling process. This study aimed to obtain and characterize the composites produced by the powder metallurgy route, with NbC and VC addition and to analyze physical properties, such as density and porosity. The powder morphologies, particle sizes and samples sintered were performed by scanning electron microscopy (SEM), X ray diffraction (XRD), laser diffraction analysis and optical microscopy (OM). The results indicate that addition of VC improves the milling efficiency, when compared to NbC addition, since it promotes a greater reduction of the particle size, directly favoring the sintering process. In this case, to achieve similar particle size, twice the milling time was required when NbC was used. The density values achieve ~ 73% of reference material for VC addition and ~ 68% for NbC and porosities varying between 27% and 38%.
DOI: 10.6084/m9.figshare.8324519
title: Microstructure evolution during the extrusion of a 6351 aluminum alloy tube

description: Abstract The aluminum alloy AA 6351 is a precipitation hardened alloy of the Al-Mg-Si system, additionally containing Mn and Fe. In this study, the microstructural characterization during processing of a thick wall extruded AA 6351 tube was carried out. Several complementary techniques for microstructural characterization were used, such as polarized light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, backscattered electron diffraction, X-ray diffraction, hardness and electrical conductivity measurements. The main characteristics of the grains and precipitates were analyzed. After solidification, the presence of a relatively homogeneous grain distribution with an average diameter of about 100 µm and an intermetallic phase with elongated morphology rich in Al, Fe, Mn and Si was observed. During extrusion, the initial grain size was reduced to about one-fifth of the initial diameter and the elongated phase, probably a-Al(Fe,Mn)Si, was fractured and redistributed and the resulting fragments were aligned in the extrusion direction. A peripheral coarse grain zone was detected and analyzed near the outer and inner surfaces of the tube.
DOI: 10.6084/m9.figshare.8324513.v1
title: Toughening of bio-PE upon addition of PCL and PEgAA

description: Abstract Researches of polymer blends based on biological and biodegradable polymers appear as a viable alternative to develop environmentally friendly materials. Therefore, the aim of this research was to produce compounds made with biological polyethylene, i.e., Biopolyethylene, Bio-PE, added to the biodegradable Polycaprolactone (PCL) and functionalized by the copolymer of polyethylene grafted with acrylic acid (PEgAA), to obtain better mechanical properties and toughen Bio-PE. Compounds were processed in a co-rotating twin screw extruder and sample tests were injection molded. The compositions investigated were: Bio-PE/PCL at 90/10, 80/20 and 70/30 wt.% without compatibilizer and upon addition of 10 phr (parts per hundred of resin) of PEgAA. The blends were characterized by X-ray diffraction (XRD), impact strength, heat deflection temperature (HDT) and scanning electron microscopy (SEM). Through XRD, it was observed that addition of PCL and PEgAA did not significantly change Bio-PE diffraction patterns. Impact strength data showed that the blends presented a tougher behavior upon addition of PCL and PEgAA. The HDT of compatibilized blend with 20wt.% of PCL was slightly higher. SEM images of compatibilized blends showed lower average particle diameters as well as absence of coalescence and aggregates.
DOI: 10.6084/m9.figshare.8324513
title: Toughening of bio-PE upon addition of PCL and PEgAA

description: Abstract Researches of polymer blends based on biological and biodegradable polymers appear as a viable alternative to develop environmentally friendly materials. Therefore, the aim of this research was to produce compounds made with biological polyethylene, i.e., Biopolyethylene, Bio-PE, added to the biodegradable Polycaprolactone (PCL) and functionalized by the copolymer of polyethylene grafted with acrylic acid (PEgAA), to obtain better mechanical properties and toughen Bio-PE. Compounds were processed in a co-rotating twin screw extruder and sample tests were injection molded. The compositions investigated were: Bio-PE/PCL at 90/10, 80/20 and 70/30 wt.% without compatibilizer and upon addition of 10 phr (parts per hundred of resin) of PEgAA. The blends were characterized by X-ray diffraction (XRD), impact strength, heat deflection temperature (HDT) and scanning electron microscopy (SEM). Through XRD, it was observed that addition of PCL and PEgAA did not significantly change Bio-PE diffraction patterns. Impact strength data showed that the blends presented a tougher behavior upon addition of PCL and PEgAA. The HDT of compatibilized blend with 20wt.% of PCL was slightly higher. SEM images of compatibilized blends showed lower average particle diameters as well as absence of coalescence and aggregates.
DOI: 10.6084/m9.figshare.8324612.v1
title: Effect of cold-working process on cyclic deformation of electrolytic copper

description: Abstract Cyclic softening and hardening processes are expressed by the change in the stress amplitude necessary to cause a given strain amplitude. Understanding the cyclic stress-strain behavior of materials is an important step in the complex study of their fatigue behavior. The potential differences between the defect structures of cold-formed materials may also be related to internal stress changes. Considering that wiredrawing and rotary swaging apply distinct forces on the material in order to obtain the product, differences may arise in the defect structures that can, consequently, affect its mechanical behavior. This study aims at evaluating and comparing, by means of strain-controlled fatigue tests, the cyclic behavior of polycrystalline electrolytic copper cold-formed by wiredrawing (WD) and rotary swaging (RS) with 87% area reduction. The fatigue test results evidenced the highest resistance to cyclic deformation presented by WD material in the low cycle regime. It was observed that the strain hardening for both cold forming conditions is related to a great increase of long-range stresses in the defect structure and the cyclic softening is related, mainly, to the subsequent drop of that stresses. The WD internal stresses resulted slightly bigger than those of the RS condition.
DOI: 10.6084/m9.figshare.8324612
title: Effect of cold-working process on cyclic deformation of electrolytic copper

description: Abstract Cyclic softening and hardening processes are expressed by the change in the stress amplitude necessary to cause a given strain amplitude. Understanding the cyclic stress-strain behavior of materials is an important step in the complex study of their fatigue behavior. The potential differences between the defect structures of cold-formed materials may also be related to internal stress changes. Considering that wiredrawing and rotary swaging apply distinct forces on the material in order to obtain the product, differences may arise in the defect structures that can, consequently, affect its mechanical behavior. This study aims at evaluating and comparing, by means of strain-controlled fatigue tests, the cyclic behavior of polycrystalline electrolytic copper cold-formed by wiredrawing (WD) and rotary swaging (RS) with 87% area reduction. The fatigue test results evidenced the highest resistance to cyclic deformation presented by WD material in the low cycle regime. It was observed that the strain hardening for both cold forming conditions is related to a great increase of long-range stresses in the defect structure and the cyclic softening is related, mainly, to the subsequent drop of that stresses. The WD internal stresses resulted slightly bigger than those of the RS condition.
DOI: 10.6084/m9.figshare.8324432
title: A social license to operate: pre-mining effects and activities perspective

description: Abstract This research proposes a new approach to recommend a responsible mining guideline on how to secure a social license to operate in Ondo state, Nigeria for oil sands mineral resources taking into account the bituminous natural effects. This is the case of bituminous oil sands in Southern Nigeria, where warm weather can induce the emission of natural bitumen fumes. Because this emission may bring occupational exposure to the local communities, mining is perceived to be an opportunity for both social-economic improvement but also an efficient approach to reduce exposure to bitumen fumes. The study investigates the importance of the perception of the society about responsible mining practices in establishing a social license for a mining operation. The results of the investigation include an appraisal of the social status, living conditions of the communities, effects of pre-mining activities and the natural impacts of bitumen from oil sand on the community. The conclusions are that the bituminous natural effects on the communities can facilitate the approval of SLO, if the company can fulfil its promises, as mining is perceived to be a welcome solution to the problems posed. In addition, the mining company must also be transparent with the community as this changes the perception of society about responsible mining practices and help in establishing SLO.
DOI: 10.6084/m9.figshare.8324432.v1
title: A social license to operate: pre-mining effects and activities perspective

description: Abstract This research proposes a new approach to recommend a responsible mining guideline on how to secure a social license to operate in Ondo state, Nigeria for oil sands mineral resources taking into account the bituminous natural effects. This is the case of bituminous oil sands in Southern Nigeria, where warm weather can induce the emission of natural bitumen fumes. Because this emission may bring occupational exposure to the local communities, mining is perceived to be an opportunity for both social-economic improvement but also an efficient approach to reduce exposure to bitumen fumes. The study investigates the importance of the perception of the society about responsible mining practices in establishing a social license for a mining operation. The results of the investigation include an appraisal of the social status, living conditions of the communities, effects of pre-mining activities and the natural impacts of bitumen from oil sand on the community. The conclusions are that the bituminous natural effects on the communities can facilitate the approval of SLO, if the company can fulfil its promises, as mining is perceived to be a welcome solution to the problems posed. In addition, the mining company must also be transparent with the community as this changes the perception of society about responsible mining practices and help in establishing SLO.
DOI: 10.6084/m9.figshare.8324435
title: Recovery of pellet feed from tailings dams

description: Abstract Not long ago, certain iron ore processing plants in Brazil were unable to efficiently recover iron ore fines and, as a result, operated only with high grade iron ore. For this reason, material stored in some iron ore tailings dams have considerable amounts of iron content with a potential to produce pellet feed fines through a concentration process. This study presents the results of magnetic concentration tests carried out on samples from four iron ore tailings dams located in Minas Gerais, named as A, B, C and D. The average iron content is 54% for A dam, 36% for B dam, 49% for C dam, and 58% for D dam. This material had a significant amount of ultra-fine particles, with more than 50% below 0.045mm for all dams, particularly the A and D dams, which present more than 80% of the below 0.045mm on average. Magnetic concentration tests were conducted on bench and pilot scales. The resulting concentrates showed the following average iron content: 66% for dam A, 63% for dam B, and 67% for dams C and D, with a mass recovery of 42% for dam A, 38% for dam B, 75% for dam C, and 63% for dam D. These results confirm the potential for pellet feed production from tailings dams through magnetic concentration.
DOI: 10.6084/m9.figshare.8324435.v1
title: Recovery of pellet feed from tailings dams

description: Abstract Not long ago, certain iron ore processing plants in Brazil were unable to efficiently recover iron ore fines and, as a result, operated only with high grade iron ore. For this reason, material stored in some iron ore tailings dams have considerable amounts of iron content with a potential to produce pellet feed fines through a concentration process. This study presents the results of magnetic concentration tests carried out on samples from four iron ore tailings dams located in Minas Gerais, named as A, B, C and D. The average iron content is 54% for A dam, 36% for B dam, 49% for C dam, and 58% for D dam. This material had a significant amount of ultra-fine particles, with more than 50% below 0.045mm for all dams, particularly the A and D dams, which present more than 80% of the below 0.045mm on average. Magnetic concentration tests were conducted on bench and pilot scales. The resulting concentrates showed the following average iron content: 66% for dam A, 63% for dam B, and 67% for dams C and D, with a mass recovery of 42% for dam A, 38% for dam B, 75% for dam C, and 63% for dam D. These results confirm the potential for pellet feed production from tailings dams through magnetic concentration.
DOI: 10.6084/m9.figshare.8324405
title: Developing a stepwise approach to simulate a hammer mill through the Whiten model - the adherence for a gold ore

description: Abstract Comminution represents a large portion of the capital and operating cost of a mineral processing plant. In 1983, Cohen estimated that comminution processes could account for 30% to 50% of the power consumption of the mill, and typically represents 50% of the operating costs of a mine. Therefore, its optimization is directly related to reduction of these operating costs. Among the crushing equipment, the hammer mill is one which is dedicated to operations that aim for a high reduction ratio with the controlled generation of fines. This crusher is recommended for friable and low abrasive ores presenting a high productive capacity. This study aims to develop a stepwise approach that allows the use of the classical crusher model (Whiten-Andersen) in modeling and simulation of circuits containing a hammer mill, simulating the resulting product according to variation of rotation speed within the equipment. The existing model for crushers developed by Whiten-Andersen considers the Perfect Mixing Model, which represents crushing through equations related to selection and breakage functions, that provide an equilibrium condition. This study aims to develop a stepwise approach that allows the use of the classical crusher model in modeling and simulation of circuits containing a hammer mill, by simulating the effect that the variation of rotation speed within the equipment implies in the generated product. The comparisons between the experimental and simulated data indicated that the model fits the data for both, P80 values and percentage passing in 19.1 mm sieve. The model created was validated based on specific experimental campaign.