Search Results (41)

Spiral concentrators are gravity and centrifugal force-based devices designed for mineral concentration. During processing operations, dynamic variations in the slurry’s liquid film thickness can induce hydrodynamic instability, generating roll waves on the free surface that compromise particle separation efficiency. To ensure operational stability and efficacy, this study establishes a theoretical shallow-water flow model for slurry dynamics in spiral concentrators based on hydraulic principles. Through L₂₇(3¹³) orthogonal experiments and real-time ultrasonic film thickness monitoring, the influence of key parameters on roll wave evolution is quantified. Results indicate that roll waves follow an “instability-development-dissipation” sequence. The pitch-to-diameter ratio (P/D) exerts a highly significant effect on roll wave intensity, while particle properties (density and size) exhibit moderate significance. In contrast, feed flow rate and solid concentration show negligible impacts. Roll waves amplify fluid turbulence, triggering stochastic migration of particles (especially low-density grains), which increases the standard deviation of zonal recovery rates (ZRR) and degrades separation precision. This work provides critical insights into particle behavior under roll wave conditions and offers a theoretical foundation for optimizing spiral concentrator design and process control. Full article

Space exploration and the prospect of developing permanent lunar settlements in the near future will require the need for innovative building construction techniques using locally sourced materials, without the need for excessive input of simple, reusable energy. The Moon’s surface is covered by regolith, a superficial layer of unconsolidated heterogeneous dusty aggregate that covers solid bedrock. This material needs to be agglomerated to create a cohesive composite that can be used as building blocks or bricks. In this study, the OPRH2N’s Lunar Regolith Simulant (LRS) was used and agglomerated with Potato (Solanum tuberosum) Starch (PS) polymer aerogel. Starch was chosen because of its excellent binding properties at very low concentrations. The resulting low-starch-containing LRS/PS aerogel composite bricks (2 and 4 wt%) were tested for their mechanical and thermal insulation performance to evaluate their potential application in lunar building structures. The composite resistance to intense beta-radiation and very large thermal amplitude was investigated to test the bricks’ resistance. This new lightweight and porous material shows promising mechanical and thermal performance, making it a potential candidate for the construction of larger structures, especially in low gravity. Full article

Gravity exploration, an Earth science method leveraging gravitational field variations due to density differences in geological structures, is a pivotal tool for subterranean investigation due to its cost-effectiveness and efficient data acquisition. This study focuses on potash, a vital agricultural resource, which forms low-density geological deposits manifesting gravitational anomalies. The research delineates favorable regions for potash enrichment within an exploration zone in Laos, utilizing gravity data, geological information, drilling records, and insights into mineralization mechanisms. The study employed analytic continuation, residual anomaly calculation, and vertical derivative analysis to interpret anomalies and identify low-density potash targets. Apparent density calculations revealed significant variations at different depths. Fault identification using integrated methods identified 16 fault lines, predominantly north–south and northeast oriented. Primary potash targets are in the northeastern and northwestern parts, with secondary targets in the central-western and southeast regions. The study acknowledges limitations such as potential field ambiguity, restricted resolution, and scarce geological data. It recommends integrating other geophysical methods, denser exploration grids, and prompt drilling for verification to refine interpretations and improve understanding, laying a solid foundation for future exploration. Full article

The iron and steel industry generates large quantities of iron-bearing dust (IBD), contributing to resource inefficiency and environmental concerns. This study investigates heating methods and the use of organic solid waste, specifically waste tire carbon (WTC), as a reductant for the recovery of Fe from sintering machine tail dust (SMTD) and steelmaking gravity dust. The results indicate that the optimal reduction conditions occurred at 1000 °C, with a 2:1 ratio of SMTD to WTC, and 0% O₂ holding for 45 min. WTC is the best material, and heating methods affect it limitedly. The leaching behavior of seven metals was measured, showing an increase in the leaching of Ca and Al compared to the raw materials. The study shows that WTC provides a promising alternative reductant for IBD reduction, offering an energy-saving and low-carbon alternative to conventional fossil fuel injections in blast furnaces. The risk of Cr leaching should be paid attention to while enhancing Fe recovery. Full article

Coal gangue, the primary bulk solid waste generated during coal utilization, requires decarbonization and the enrichment of valuable components such as calcium and magnesium through methods like hydrocyclone separation for comprehensive utilization. This study observed the free-settling behavior of coal gangue particles using a high-speed dynamic image analysis system and analyzed their kinematic characteristics to guide the hydrocyclone separation process. The results indicate that particle size and density significantly influence settling behavior. Fine-grained, low-density particles exhibited more pronounced directional deflection and velocity fluctuations, while high-density coarse particles demonstrated higher settling velocities. Based on terminal velocity, the drag coefficient of fluid resistance acting on particles was calculated. The findings show that high-density coarse particles have larger drag coefficients, likely due to fluid disturbances and the hydrophobic nature of particle surfaces. Additionally, the mechanical properties of settling motion were analyzed, indicating that gravity dominates the settling process of coarse particles, while fine particles are subjected to relatively balanced forces. Furthermore, density variations primarily affect hydrodynamic drag, which is related to the surface properties of particles. Therefore, enhancing the centrifugal force field through cyclone structural optimization is necessary to improve separation precision for fine coal and gangue particles. Full article

Gravity energy storage, a technology based on gravitational potential energy conversion, offers advantages including long lifespan, environmental friendliness, and low maintenance costs, demonstrating broad application prospects in renewable energy integration and grid peak regulation. This paper reviews the technical principles, characteristics, and application progress of liquid gravity energy storage (LGES), like pumped hydro storage (PHS) and solid gravity energy storage (SGES) systems—tower-based (T-SGES), shaft-type (S-SGES), rail-mounted (R-SGES), and mountain gravity energy storage (M-SGES). PHS, the most mature technology, is widely deployed for large-scale energy storage but faces significant geographical constraints. T-SGES and R-SGES exhibit higher flexibility for diverse terrains, while S-SGES leverage abandoned mines for resource reuse. Despite advantages such as high round-trip efficiency and extended lifecycle, challenges remain in efficiency optimization, high initial investments, and land utilization. Future development of gravity energy storage will require technological innovation, intelligent dispatch systems, and policy support to enhance economic viability and accelerate commercialization. Full article

Korla fragrant pear is a high-quality local pear variety native to Xinjiang, China. Currently, the low fruit-setting rate and low calyx shedding rate problems in Korla fragrant pears have been highlighted, which seriously affect the fruit yield and quality. It is of great significance to research the fruiting characteristics and molecular-assisted identification of Korla fragrant pear bud mutation materials for enriching the germplasm resources of Korla fragrant pear. In this research, a natural pollination group (YB) of Korla fragrant pear bud mutation materials and a natural pollination group (CK) of Korla fragrant pears were established. On the fruiting characteristics, the fruit-setting rate and calyx-removal rate of the two groups were investigated. In terms of fruit quality, the fruit shape index, fruit specific gravity, soluble solids content, sugar:acid ratio, soluble sugar content, and other indicators were measured. For the anatomical structure of the calyx tube, the detachment cells were observed. The formation time of the two groups of detached cells was compared. In the GBS simplified genome sequencing, a phylogenetic tree was constructed based on the obtained SNP sites. A principal component analysis, population genetic structure analysis, and genetic diversity index analysis were carried out. In the aspect of SSR molecular marker identification, the SSR types were counted. Polyacrylamide gel electrophoresis was performed. The results demonstrate the following: (1) the fruit-setting rate (30.87%) and calyx-removal rate (68.11%) in the YB group were significantly higher than those in the CK group (19.37%) and the calyx-removal rate (55.18%). (2) There was no significant difference in fruit quality indexes, such as average fruit weight (127.10–130.00 g) and soluble sugar content (9.47–9.56%) between the two groups. (3) Abscission-layer cells were observed at 2, 4, 6, 8, and 10 h after calyx tube discoloration in the YB group and at 48, 72, and 96 h after calyx tube discoloration in the CK group. (4) The genetic background of the YB group and the CK group was similar at the GBS level, but there were differences at the DNA level. This research finally shows that Korla fragrant pear bud mutation material is a good germplasm resource. This germplasm resource can promote the structural optimization of Korla fragrant pear varieties and the healthy development of the industry. Full article

Gravity settling is a widely employed technology that removes oil from produced water in oilfields. However, with the transition of reservoir development to low-permeability reservoirs, conventional produced water settling tanks face limitations in the treatment efficiency and coagulant dosage. This study presents an innovative approach that optimizes sedimentation tank structures and integrates micro-vortex flow technology to enhance coagulation and flocculation. Through chemical dosage experiments, comparative experiments, and long-term observation, the micro-vortex flow reactor demonstrates a 9.4% increase in oil removal efficiency while reducing the coagulant dosage by 30.0%. The MOR equipment achieved a 20.5% higher oil removal efficiency than conventional methods while maintaining effluent oil and suspended solids below 20 mg/L. The long-term observation experiment of MOR equipment further highlights oil removal efficiency of 94.2% and the micro-vortex reactor’s excellent anti-pollution performance. The MOR equipment significantly reduces the land occupancy area by over 50% compared to conventional methods, thanks to the implementation of micro-vortex flow technology that effectively addresses the limitations associated with traditional settling tanks. This study contributes to advancing efficient and sustainable practices in waterflooding reservoirs, particularly for meeting stringent standards of water injection in low-permeability oilfields. Full article

Acceptable zircon for composite formulation in the aerospace industry requires that the mineral contains a minimum of 65% zirconia (ZrO₂). Despite having vast deposits of zircon, Nigeria’s aerospace industry has historically relied primarily on imported mild steel tubes for solid rocket motor cases (SRMCs) construction, resulting in three major challenges: low strength-to-weight ratio, pressure, and temperature containment. In this study, the Arikya zircon deposit located in northern Nigeria was investigated with the aim of upgrading low-grade zircon ore using magnetic and gravity separation processes for use in composite formulation for SRMCs. The dry high-intensity magnetic separator (DHIMS) produced a ZrO₂ grade of 52.48%, recovery of 57.99%, and an enrichment ratio of 0.78 with a separation efficiency of 0.56, while the air-floating separator (AFS) generated the highest of 65.52% ZrO₂ grade with 70.81% recovery and enrichment ratio of 1.25 with a separation efficiency of 0.25. The ZrO₂ content increased from 40.77 to 65.52% after beneficiation. Iron oxide and titanium dioxide contaminants at 0.73 and 0.83% were reduced to 0.66 and 0.54%, respectively, while the specific gravity increased from 4.4 to 4.6 g/cm³. The ZrO₂ content and specific gravity were improved to the minimum standard specified for zirconia-reinforced composite application and competed effectively with industrially/globally accepted zircon. These results demonstrated the efficacy of combining DHIMS and AFS to upgrade the low-grade zircon ore from Arikya, Nasarawa State. Full article

Egyptian Jallab (EJ) is a conical candy (light to dark brown), manufactured from a part of sugar cane juice, that is used in the black honey industry. EJ is considered an unrefined sugar or a non-centrifugal form of sugar. The traditional use of Jallab is as candy, but it can also be used for making ice cream, cupcakes, biscuits, and toffee, as well as being used in other food applications. In this study, EJ was used as a sugar substitute in ice cream at 0, 25, 50, 75, and 100%. Total solids, titratable acidity, pH, protein, ash, fat, specific gravity, weight per gallon, viscosity, color attributes, total antioxidant activity, total phenolic content, and total flavonoid contents, as well as microbiological analyses, were tested. The total solids, protein, and ash in the Egyptian Jallab ice cream (EJIC) increased from 39.30, 4.85, and 0.87 to 41.19, 6.36, and 1.42, respectively. The gradual sugar substitution led to a significant increase in specific gravity and weight per gallon in pounds. The lightness (L*) of the ice cream decreased significantly due to the substitution of EJ for sugar. Moreover, there was a significant increase in a* (from 0.147 in control samples to 5.52 in treatment 4, which had 100% EJ). The changes in the b* values of Jallab ice cream samples were significantly increased due to the substitution of EJ for sugar. The control samples had a low value of antioxidant activity (21.53%) when compared with the treatment, which has EJ (88.82, 89.96, 91.98, and 92.14%) for EJIC1, EJIC2, EJIC3, and EJIC4, respectively. The total phenolic contents are 2.07, 3.03, 4.14, and 4.68 fold higher in the treatments with EJ substituted for sugar than in the control samples. Total flavonoid contents increased from 5.73 mg QE g⁻¹ in control samples (TC) to 14.68, 21.54, 30.48, and 34.15 mg QE g⁻¹ in EJIC1, EJIC2, EJIC3, and EJIC4 mg QE g⁻¹ in ice cream samples, respectively. Full article

Solid–liquid separation is a fundamental operation in process engineering and thus an important part of many process chains in the preparation of slurries in the chemical industry and other parts of the industrial environment. For the separation of micron-sized particles which, due to their size, do not settle or settle very slowly in the earth’s gravity field, centrifuges are often used. The preferred choice are often decanter centrifuges because they work continuously and stabilize the process against product fluctuations due to their adjustment possibilities. The design of the apparatus is complex: The main components of the apparatus are the cylindrical-conical bowl, which rotates at a high speed, and a screw located inside the bowl, which rotates in the same direction at a low differential speed to transport the separated solids out of the apparatus. Geometrical properties of the apparatus, as well as the adjustable operating parameters, such as rotational speed or differential speed, have a significant influence on the separation. In practice, analytical models and the experience of the manufacturers form the basis for the design. Characteristics of the disperse phase, interactions with the liquid, as well as the influence of the flow on the separation, are not taken into account. As a consequence, the transfer to industrial scale always requires a large number of pilot-scale experiments, which are time-consuming and expensive. Due to the increasing computational power, computational fluid dynamics (CFD) provides one possibility to minimize the experimental effort in centrifuge design. In this work, the open-source software OpenFOAM is used to simulate the multi-phase flow in a laboratory decanter centrifuge. For validation, experiments were carried out on a laboratory scale and the main operating parameters, such as speed, differential speed, and volume flow rate, were varied. The simulation results show a good agreement with the experimental data. Furthermore, the numerical investigations show the influence of the flow on the separation of the particles. To evaluate the transportability of a material, the transport efficiency was introduced as a dimensionless parameter. In addition, the simulation allows the consideration of the individual velocity components, making it possible to generate an impression of the complex three-dimensional flow in the apparatus for the first time. Full article

Gravity pier is a widely employed pier type in railway bridges worldwide. It is characterized by a solid cross-section with a low longitudinal reinforcement ratio which can be even lower than 0.5%. These low-reinforced gravity piers have been found to be vulnerable under major earthquakes, but their seismic performance has not been fully understood. Improving the seismic safety of these piers and reducing the consumption of reinforcing steels coincide with multiple Sustainable Development Goals (SDG 6, 7, and 9). In this concern, three main objectives are achieved in the present research. Firstly, quasi-static tests were conducted on two gravity piers with low longitudinal reinforcement ratios: 0.3% and 0.4%. The tests found the reinforcement ratio significantly affected the failure mode and seismic capacity. A typical brittle failure was observed in the specimen with the 0.3% reinforcement ratio. Fracture of longitudinal reinforcing steels was heard, and only a few cracks formed within a narrow region at the pier bottom, whereas the structural behavior of the specimen with a 0.4% reinforcement ratio was ductile, and cracks were located within a wider region (800 mm) at the pier bottom. Increasing the reinforcement ratio significantly increased the energy dissipation capacity and the displacement ductility. Secondly, finite element models of two specimens built using ANSYS were validated with test results, and then a series of finite element models were built to further investigate the influences of three important parameters on the seismic capacity. The three parameters are shear span to depth ratio, axial compression ratio, and longitudinal reinforcement ratio. The validations found that the load–displacement hysteretic curves and the distributions of concrete plastic strain from finite element analyses matched well with those from tests. Further finite element analyses found that the shear span to depth ratio was inversely correlated with the peak lateral load, but positively correlated with the displacement ductility. Conversely, increasing the axial compression ratio increased the peak lateral load but decreased the displacement ductility. Thirdly, an analytical equation was proposed to predict the displacement ductility of low-reinforced gravity piers, and the predicted ductilities agreed well with those obtained from finite element analyses. The findings provide a better understanding of the seismic performance of low-reinforced gravity piers, which helps extend the application of these piers. Furthermore, the proposed analytical equation assists in the evaluation and design of these piers. Full article

Drilling cuttings from the rock formation generated during the drilling process are generally smashed to fine particles through hydraulic cutting and grinding using a drilling tool, and then are mixed with the drilling fluid during circulation. However, some of these particles are too small and light to be effectively removed from the drilling fluid via solids-control equipment. These small and light solids are referred to as low gravity solids (LGSs). This work aimed to investigate the effect of LGSs on the performance of oil-based drilling fluid (OBDF), such as the rheological properties, high-temperature and high-pressure filtration loss, emulsion stability, and filter cake quality. The results show that when the content of LGSs reached or even exceeded the solid capacity limit of the OBDF, the rheological parameters including the plastic viscosity, gel strength, and thixotropy of OBDF increased significantly. Furthermore, the filtration of OBDF increases, the filter cake becomes thicker, the friction resistance becomes larger, and the stability of emulsion of OBDF also decreases significantly when the concentration of LGSs reached the solid capacity limit of OBDF (6–9 wt% commonly). It was also found that LGSs with a smaller particle size had a more pronounced negative impact on the drilling fluid performance. This work provides guidance for understanding the impact mechanism of LGSs on drilling fluid performance and regulating the performance of OBDF. Full article

In this study, we present the feasibility of using gravity measurements made with a small inertial navigation system (INS) during in situ experiments, and also mounted on an unmanned aerial vehicle (UAV), to recover local gravity field variations. The INS operated is the SPATIAL one developed by Advanced Navigation, which has three-axis accelerometers. When the temperature bias is corrected, these types of INS are powerful enough to present the periodic signal corresponding to the solid Earth tides. There is also a clear correlation with the data measured at different altitudes by a CG5 gravimeter. However, these data were recorded on static points, so we also studied the INS in a moving platform on a UAV. Because there are a lot of vibrations recorded by the INS (wind, motor, on-board computer), the GPS and accelerometric data need to be filtered extensively. Once the data are corrected so they do not show thermal bias and low-pass filtered, we take the second derivative of the altitude (GPS) data to find the radial accelerometry of the drone and compare it to the radial accelerometry measured directly by the INS, in order to isolate the accelerometric signal that is related to the area that is being studied and the altitude. With a high enough precision, this method could be used to obtain the gravity variations due to the topography and density variations in the ground. Full article

Laser powder bed fusion (LPBF) is of great importance for the visual measurement and analysis of the metallization process, which is the process of solid, liquid, and gas phase transformations of metal powders under high-energy laser irradiation due to the low boiling point/high saturated vapor pressure. Since the evaporation of metals involves the interaction of driving forces such as vapor back pressure, surface tension, and gravity, the movement of the melt pool is not stable. At the same time, it also produces vaporization products such as vapor plumes and sprays, which cause defects such as bubbles, porosity, lack of fusion, inclusions, etc., during the manufacturing process of the parts, affecting the performance and manufacturing quality of the parts. More and more researchers are using imaging technologies, such as high-speed X-ray, high-speed visible light cameras, and high-speed schlieren imaging, to perform noncontact visual measurements and analyses of the melt pool, vapor plume, and spatter during the metal evaporation process, and the results show that the metal evaporation process can be suppressed by optimizing the process parameters and changing the processing atmosphere, thereby reducing part defects and improving part performance and built part quality. This paper reviews the research on metal evaporation mechanisms and visual measurement methods of metal evaporation, then discusses the measures of metal evaporation, and finally summarizes and prospects the future research hotspots of LPBF technology, according to the existing scholars’ research on numerical simulation analysis and visual measurement methods of the metal evaporation process. Full article