Collision Probability Research Articles

Resource Allocation in UAV-D2D Networks: A Scalable Heterogeneous Multi-Agent Deep Reinforcement Learning Approach

In unmanned aerial vehicle (UAV)-assisted device-to-device (D2D) caching networks, the uncertainty from unpredictable content demands and variable user positions poses a significant challenge for traditional optimization methods, often making them impractical. Multi-agent deep reinforcement learning (MADRL) offers significant advantages in optimizing multi-agent system decisions and serves as an effective and practical alternative. However, its application in large-scale dynamic environments is severely limited by the curse of dimensionality and communication overhead. To resolve this problem, we develop a scalable heterogeneous multi-agent mean-field actor-critic (SH-MAMFAC) framework. The framework treats ground users (GUs) and UAVs as distinct agents and designs cooperative rewards to convert the resource allocation problem into a fully cooperative game, enhancing global network performance. We also implement a mixed-action mapping strategy to handle discrete and continuous action spaces. A mean-field MADRL framework is introduced to minimize individual agent training loads while enhancing total cache hit probability (CHP). The simulation results show that our algorithm improves CHP and reduces transmission delay. A comparative analysis with existing mainstream deep reinforcement learning (DRL) algorithms shows that SH-MAMFAC significantly reduces training time and maintains high CHP as GU count grows. Additionally, by comparing with SH-MAMFAC variants that do not include trajectory optimization or power control, the proposed joint design scheme significantly reduces transmission delay.

Trajectory reconstruction method for spacecraft formation considering collision probability constraints

Abstract This paper introduces a trajectory reconstruction algorithm for spacecraft formation, combining collision probability and sequential convex programming algorithms. When reconstructing the trajectory of spacecraft formation, external collision avoidance constraint is added to avoid collision threats from space objects. The constraint accuracy of the external collision avoidance constraints of the BOX method and the collision probability method is analyzed. The simulation results indicate that the collision probability method has higher accuracy compared to the BOX method. It addresses the issue of inaccurate division of collision avoidance zones in the BOX method, which tends to be aggressive in the velocity direction and conservative in other directions. A reference is provided for trajectory reconstruction when formation satellites encounter non-cooperative targets.

Study on the effect and mechanism of coarse magnetite on the flotation of fine-grained hematite

Lean hematite ore is one of the refractory iron ores in China due to its fine crystal size, deep oxidation degree and complex mineral composition. With the deep mining of mine ore, the disseminated particle size of iron minerals is finer, and the ore properties are more complex and difficult to be separated. Therefore, the research on high-efficiency beneficiation technology of fine-grained lean hematite ore is the requirement and important direction of the development of refractory iron ore beneficiation. In this paper, the carrier flotation method is used to comprehensively recover hematite, and the addition of coarse-grained magnetite can effectively improve the recovery rate of fine-grained hematite. The flotation results show that when the ratio of magnetite to hematite is 1: 1, the recovery rate of iron ore can reach more than 96.34%, and the efficient recovery is realized. Based on the results of pure mineral test, the carrier flotation test of Anshan lean hematite ore was carried out. The results show that the reverse flotation concentrate product with TFe grade of 67.88% and total iron recovery of 84.81% can be obtained, and the TFe grade of the reverse flotation tailings is 24.20%. It can be seen that compared with the traditional process, the grade of carrier flotation tailings is 2.37 percentage points lower than that of the original reverse flotation tailings; the carrier reverse flotation process can effectively improve the recovery rate of iron concentrate. In addition, the theoretical analysis of carrier flotation was carried out by contact angle, zeta potential, mineral phase microscope, SEM and XPS. It was found that the collision probability between fine mineral particles and bubbles was low, which limited the recovery of fine mineral particles in the flotation process. Fine-grained hematite can be non-selectively attached to the carrier particles, thereby affecting the adsorption of starch on it, thereby improving the recovery rate of fine particles; The carrier reverse flotation can further improve the flotation efficiency by gravity and shear force. Carrier reverse flotation provides a new idea for effective recovery of iron ore.

Comparison of Cognitive Functions Between Individuals With Chronic Low Back Pain With High and Low Pain Catastrophizing and Pain-free Controls: A Cross-sectional Study.

Researchers suggested that the interruptive effects of chronic pain on cognitive functions may be modulated by the level of pain catastrophizing (PC). However, in individuals with chronic low back pain (CLBP), domains of cognitive function that may be affected by the level of PC remain largely unclear. Therefore, this study aimed to compare cognitive functions between individuals with CLBP with high and low PC and pain-free controls. This cross-sectional study examined cognitive functions of 42 individuals with CLBP and 21 pain-free controls. The PC scale was used to stratify participants with CLBP into high and low PC. Participants performed 5 cognitive tests from the Cambridge Neuropsychological Test Automated Battery, namely 5-choice reaction time, rapid visual processing, spatial working memory, attention switching task, and stop signal task. The statistical analyses revealed that compared with individuals with CLBP with low PC and pain-free controls, individuals with high PC demonstrated greater values of the between errors ( P =0.01), reaction latency ( P <0.001), and stop signal reaction time variables ( P =0.004, 0.003, respectively) but lower values of probability of hit ( P =0.02, 0.01, respectively), A' ( P =0.01, <0.001, respectively), and percent correct trials variables ( P =0.002, <0.001, respectively). The results of the current study showed deficits in sustained attention, working memory, cognitive flexibility, and inhibitory control in individuals with CLBP with high PC. From a clinical perspective, therapeutic interventions targeting PC should be considered to decrease catastrophic thinking about pain in individuals with CLBP. Additional research is warranted to explore cognitive functioning as an outcome of these interventions in individuals with CLBP.

The exploration of effect for nano-Al2O3 on solid waste based superfine tailings cemented paste backfill: Pyrolysis property, hydration mechanism and environmental risk

Resource utilization of superfine tailings has become a key research direction in filling mining. This study analyzes the mechanical properties, pyrolysis mechanism and hydration mechanism of nano-Al2O3(NA)-doped solid waste based superfine tailings cemented paste backfill (SWSCPB) by multiple microscopic characterization methods and pyrolysis kinetic theory. The results show that the main temperature interval for the pyrolysis of SWSCPB to happen is 280–900 °C, which is divided into two stages of dehydroxylation and decarbonization. The apparent activation energy(E) and pre-index factor(A) of pyrolysis are higher than those of NA0 and NA2 at 1 % NA dosage, indicating that NA increases the energy barrier of pyrolysis, the percentage of activated molecules, and the collision probability of hydration products in SWSCPB, but decreases due to agglomeration at exceeds 1 % NA dosage. NA can enhance macroscopic strength of SWSCPB, with the highest strength at 1 % NA dosage. Compared with NA0 and NA2, more hydration products such as AFt and C-(A)-S-H are present in NA1, and the distribution of Q2 and Q4 in C-(A)-S-H is more pronounced, with a higher degree of polymerization, a stronger tendency for the conversion of non-bridging to bridging oxygen bonds, and fewer pores in the microstructure of SWSCPB. The NA dosage can provide more nuclei for the formation of AFt, C-(A)-S-H in SWSCPB, and can also promote the replacement of Si by Al for the conversion of C-S-H to C-(A)-S-H with higher polymerization. In addition, the leaching risk and mechanism of heavy metal ions from SWSCPB are preliminarily explored in combination with leaching experiments. The results provide new insights and guidance for the application of SWSCPB in filling mining under cleaner production targets.

Safe and Efficient Path Planning Under Uncertainty via Deep Collision Probability Fields

Safe and Efficient Path Planning Under Uncertainty via Deep Collision Probability Fields

Catalytic membrane with dual-layer structure for ultrafast degradation of emerging contaminants in surface water treatment

The catalytic membrane-based oxidation-filtration process integrates physical separation and chemical oxidation, offering a highly efficient water purification strategy. However, the oxidation-filtration process is limited in practical applications due to the short residence time of milliseconds within the catalytic layer and the interference of coexisting organic pollutants in real water. Herein, a dual-layer membrane containing a top selective layer and a bottom catalytic layer was fabricated using an in situ co-casting method with a double-blade knife. Experimental results demonstrated that the selective layer rejected macromolecular organic pollutants, thereby alleviating their interference with bisphenol A (BPA) degradation. Concurrently, the catalytic layer activated peracetic acid oxidant and achieved a high BPA degradation exceeding 90 % in milliseconds with reactive oxygen species (especially •OH). The finite-element analysis confirmed a high-concentration reaction field occupying the pore cavity of the catalytic layer, enhancing collision probability between reactive oxygen species and BPA, i.e., the nano-confinement effect. Additionally, the dual-layer membrane achieved a long-term stable performance for emerging contaminant degradation in surface water treatment. This work underscores a novel catalytic membrane structure design for high-performance oxidation-filtration processes and elucidates its mechanisms underlying ultrafast degradation.

Electric Demulsification Membrane Technology for Confined Separation of Oil-Water Emulsions.

Demulsification technology for separation of oil-water (O/W) emulsions, especially those stabilized by surfactants, is urgently needed yet remains highly challenging due to their inherent stability characteristics. Electrocoalescence has emerged as a promising solution owing to its simplicity, efficacy, and versatility, yet hindered by substantial energy consumption (e.g., >50 kWh/m3) along with undesirable Faradic reactions. Herein, we propose an innovative electric demulsification technology that leverages conductive membrane microchannels to confine oil droplets from the oil-water emulsion for achieving high energy-efficient coalescence of oil droplets. The proposed system reduces the required voltage down to 12 V, 2 orders of magnitude lower than that of conventional electrocoalescence systems, while achieving a similar separation efficacy of 91.4 ± 3.0% at a low energy consumption (3 kWh/m3) and an ultrahigh permeability >3000 L/(m2·h·bar). In situ fluorescence microscopy combined with COMSOL simulations provided insight into the fundamental mechanistic steps of an electric demulsification process confined to membrane microchannels: (1) rapid electric-field redistribution of oil droplet surfactant molecules, (2) enhanced collision probability due to confined oil droplet concentration under dielectrophoretic forces, and (3) increased collision efficacy facilitated by the membrane pore structure. This strategy may revolutionize the next generation of demulsification and oil-water separation innovations.

Single-Nanometer Spinel with Precise Cation Distribution for Enhanced Oxygen Reduction.

Designing spinel nanocrystals (NCs) with tailored structural composition and cation distribution is crucial for superior catalytic performance but remarkably challenging due to their intricate nature. Here, an aggregation growth restricted hot-injection method is presented by meticulously investigating the fundamental nucleation and aggregation-driven growth kinetics governing spinel NC formation to address this challenge. Through controlled collision probability of nuclei during growth, this approach enables the synthesis of spinel NCs with unprecedented, single nanometer (1.2nm). Single-nanometer CoMn2O4 spinel via this method exhibits a highly tailored structure with a maximized population of highly active octahedral Mn atoms, thereby optimizing oxygen intermediate adsorption during oxygen reduction reaction (ORR). Consequently, it exhibits a remarkable half-wave potential of 0.88V in ORR and leads to a superior power density (170.9mW cm-2) in zinc-air battery, outperforming commercial Pt/C and most reported spinel oxides, revealing a clear structure-property relationship. This structure design strategy is readily adaptable for the precise synthesis and engineering of various spinel structures, opening new avenues for developing advanced electrocatalysts and energy storage materials.

Advanced nanobubble flotation for enhanced removal of sub-10 µm microplastics from wastewater.

Sub-10 µm microplastics (MPs) in aquatic environments pose significant ecological and health risks due to their mobility and potential to carry harmful microcontaminants. Our effluent analysis from a Hong Kong Sewage Treatment Works shows that traditional treatment often fails to effectively remove these MPs. These small-sized MPs are commonly neglected due to challenges in accurate quantification, analysis, and removal. This study introduces a nanobubble-assisted flotation process that enhances the removal efficiency of both regular and irregular small-sized MPs from wastewater. The proposed process outperforms the traditional flotation process by fostering a more effective interaction between bubbles and MPs, increasing removal rates of MPs from 1 µm to 10 µm by up to 12% and providing a total efficiency boost of up to 17% for various particle sizes. Improvements are attributed to enhanced collision and adhesion probabilities, hydrophobic interactions, as well as better floc flotation. Supported by empirical evidence, mathematical models, and Molecular Dynamics simulations, this research elucidates the nanoscale mechanisms at play. The findings confirm the nanobubble-assisted flotation technique as an innovative and practical approach to removing sub-10 µm MPs in water treatment processes.

Excess Energy Released Due To Proton-Proton Collisions in Condensed Matter Could Be Due To Laboratory-Made Micro Black Holes

While sodium metal dissolution in concentrated (2M) Epsom solution is very peaceful under stirring conditions in about 5 to 10s, its dissolution in a dilute (0.85) Epsom solution has turned very violent. Nearly 30s after the addition of Na, the solution exploded accompanied by the vaporization of the glass beaker. Only sodium aerosol and tiny molten needles of glass were seen around indicating a very high temperature (&gt;1000 0C) has indeed been reached. The timing of the explosion has indicated that hydrogen released during sodium dissolution has got trapped in the salt solution and subsequent energy build-up has caused the excess energy release. A viable trapping mechanism involving the exchange of 2 hydrogen ions (H22+) with an Mg2+ ion in cavitation-induced nanocrystals of Epsom has been proposed in this regard. The two hydrogen ions are stabilized at the cation vacancy (cavity) by dative bonds with the two hydrogen ions in the water molecule trapped at a neighboring sulphate vacancy. Spring-like action between the two protons trapped at the cation vacancy due to oscillations caused by two opposing forces – one by cavitation and the other by coulombic repulsion eventually appear to have led to the collision of hydrogen ions at relativistic speeds in condensed matter. To start with, the two protons in the H22+ species are confined in a small space (72 pm cavity) at a single crystal cation lattice site in Na2SO4 nanocrystal which increases their head-on collision probability at high energies. There is no upper limit to the energies achieved through p-p collisions in this species as the Cavitation-Coulombic Repulsion Oscillations (CCRO) can continue until the endpoint is reached. Regeneration of a nanocrystal over a sufficiently small time scale and regeneration effect prior to cavitation collapse are all important so laws of thermodynamics are not violated. Extra dimensions of gravity at short distances, if present, could also assist in the high energies required for the production of mini black holes in condensed matter. Such black holes lose mass very quickly through the emission of Hawking radiation observed in the form of explosion with mass-energy equivalence of E = mc2. The possibility of tapping such explosive energy for peaceful purposes is discussed. As such it constitutes the third kind of atomic energy humans have entertained, the first two being fission and fusion.

Not all maps are equal: Evaluating approaches for mapping vessel collision risk to large baleen whales

Abstract A growing and increasingly globalised human population, requiring the movement of goods and commodities, is placing increasing demands on the maritime industry, resulting in a concurrent increase in global shipping activities. This has consequences for the marine environment, particularly for species vulnerable to the impacts of vessel traffic. For example, vessel collisions can result in sub‐lethal or fatal injuries for marine mammals, whilst vessel noise can cause acoustic masking that effectively reduces an animal's listening space, potentially impacting their communication, navigation and foraging capacity. While a number of parallel approaches to mapping collision risk to large whales have arisen, these methods vary in their focus, usually on either co‐occurrence, collision probability, or probability of mortality. However, little attention has been given to the implications of methodological choice and data selection on subsequent risk predictions. To assess differences between these approaches, we used a standardised input dataset comprised of telemetry‐point data from tagged bowhead whales, and satellite‐based Automated Identification System (AIS) data of spatial vessel movements covering the Davis‐Baffin Arctic Marine Area. We applied this data to eight different, previously published analyses for deriving areas of vessel risk. We found that the choice of risk mapping approach affected the location, and total area, identified as ‘high risk’, and that more computationally complex approaches did not necessarily equate to different predictions. There was considerable variation in the total area of ‘high risk’ predicted within each map (range = 20–42,246 km2). Synthesis and Applications. The results underscore the importance of methodological transparency, informed data selection and careful interpretation when predicting collision risk. We provide practical recommendations for enhancing transparency when predicting risk, and discuss choice of approach suitable for different situations or management applications. It is critical that managers and policy makers are aware of the implications of applying different approaches when interpreting risk evaluation outputs.

Probabilities of collisions of bodies ejected from forming Earth with the terrestrial planets

During formation of the Earth and at the stage of the Late Heavy Bombardment, some bodies collided with the Earth. Such collisions caused ejection of material from the Earth. The motion of bodies ejected from the Earth was studied, and the probabilities of collisions of such bodies with the present terrestrial planets were calculated. The dependences of these probabilities on velocities, angles and points of ejection of bodies were studied. These dependences can be used in the models with different distributions of ejected material. On average, about a half and less than 10 % of initial ejected bodies remained moving in elliptical orbits in the Solar System after 10 and 100 Myr, respectively. A few ejected bodies collided with planets after 250 Myr. As dynamical lifetimes of bodies ejected from the Earth can reach hundreds of million years, a few percent of bodies ejected at the Chicxulub and Popigai events about 36–65 Myr ago can still move in the zone of the terrestrial planets and have small chances to collide with planets, including the Earth. The fraction of ejected bodies that collided with the Earth was greater for smaller ejection velocity. The fractions of bodies delivered to the Earth and Venus probably did not differ much for these planets and were about 0.2–0.3 each. Such obtained results testify in favour of that the upper layers of the Earth and Venus can contain similar material. The fractions of bodies ejected from the Earth that collided with Mercury and Mars did not exceed 0.08 and 0.025, respectively. The fractions of bodies collided with Jupiter were of the order of 0.001. In most calculations the fraction of bodies collided with the Sun was between 0.2 and 0.5. Depending on parameters of ejection, the fraction of bodies ejected into hyperbolic orbits could vary from 0 to 1. Small fractions of material ejected from the Earth can be found on other terrestrial planets and Jupiter, as the ejected bodies could collide with these planets. Bodies ejected from the Earth could deliver organic material to other celestial objects, e.g. to Mars.

Pedestrians' street-crossing decisions compared between conventional and electric vehicles

To safely cross a road before an approaching vehicle, pedestrians need to accurately judge the vehicle's motion. Recent studies from our lab demonstrated that the noise emitted by a vehicle conveys important information about its motion, particularly in the case of accelerating approaches. Here, we compared street-crossing decisions between conventional (ICEVs) and electric vehicles (EVs) with or without AVAS sounds. The experiment presented high-fidelity audiovisual VR simulations of approaching vehicles, based on recordings of real ICEVs and EVs. The presented velocity profiles included a large variation in acceleration rates, a = 0 to 4.4 m/s^2, and two velocities at the moment of the crossing decision (28 km/h versus 50 km/h). To investigate whether the lower sound level of EVs compared to ICEVs contributes to differences in crossing decisions, we additionally presented a condition in which the sound levels were matched between vehicle types. All experimental conditions were presented in two modality conditions (auditory-only and audiovisual). We compare the crossing decisions between vehicle types, velocity profiles and level profiles in terms of collision probabilities estimated from the measured psychometric functions. Preliminary results confirm differences between crossing decisions made in interaction with EVs compared to ICEVs, reduced in the level-matched conditions.

Research on deep reinforcement learning-based complex crowd navigation algorithm using risk perception and path selection

Abstract Aiming at the Frozen Robot Problem and the poor effect of dynamic obstacle avoidance in traditional navigation methods when encountering dynamic obstacles, a deep reinforcement learning navigation method based on risk perception and path selection is proposed. The core of this method lies in CP (Collision Probability) module and IOU (Intersection over Union) module. The CP module calculates the CP between the robot and the nearby dynamic obstacles in real time, so that the robot can avoid the dangerous obstacles first. At the same time, the intersection-merging ratio module calculates the “pass ability” of the area near the robot in real time, and guides the robot to choose a safer area to pass through. Compared with the DRL method without these two modules, the proposed method achieves the highest navigation success rate in all simulation test environments, and the maximum improvement rate is 11%. At the same time, it still has advantages in navigation time and other indicators.

Drifting vessel statistics and emergency towing cases

Abstract Recent climate studies forecast violent weather events with impact on the safety of maritime transportation. For example, harsh weather may result in system failures such as blackouts or loss of steering capability. Problems met when performing planned maintenance at sea may lead to adverse events if the weather cause delays or makes it impossible to complete the planned work. A drifting vessel in general is a liability for collisions with offshore structures, groundings, and total loss due to capsizing. The increasing use of ocean structures for energy production at sea (coastal and deepwater windfarms) and the transfer of fish farming structures to more exposed locations increase the probability of collisions between drifting ships and ocean structures. To mitigate risks, several incidents and their consequences have been analysed by national administrations. In some cases, these analyses have recommended the use of dedicated emergency towing resources. The willingness of the national governments to fund such resources is directly related to the time since the last major incident in their territorial waters. This paper reviews some recent cases of emergency towing operations in Norwegian waters and highlights challenges interlinked to setting up an emergency towing connection between a drifting ship and an emergency towing vessel in harsh weather.

Effect of mesh aluminum alloy on hydrogen and propane explosion characteristics

In order to explore the effect of mesh aluminum alloy (MAA) on the explosion characteristics of different types of gases, experiments were conducted by filling MAA in hydrogen and propane explosion pipes. The explosion characteristic parameters of hydrogen and propane with different volume fractions under the action of MAA were obtained. The chain reaction process and thermodynamic reaction mechanism of hydrogen and propane explosions were studied using the numerical simulation software CHEMKIN-PRO and Materials Studio. The experimental results show that MAA significantly promotes hydrogen explosions but inhibits propane explosions. Simulation results show that ·H, ·O, and ·OH are key radicals in the hydrogen explosion process. As the hydrogen volume fraction increases, the number of radicals in the reaction system also increases. When MAA is filled in the hydrogen explosion test pipe, the turbulence of the flame structure inside the pipe increases the collision probability between key radicals such as ·H, ·O, and ·OH, sharply increasing the temperature of the explosion reaction system, resulting in a promoting effect of MAA on hydrogen explosions. When MAA is introduced into the propane explosion test pipe, it creates a barrier and wall effect. This reduces the number of key radicals in the reaction system and lowers the likelihood of radical collisions, which slows down the rates of multiple chain reactions and inhibits the propane explosion. Thermodynamically, it can be seen that propane requires more energy than hydrogen for key elementary reactions to explode, making it more difficult to react.

Hybrid vehicular access protocol and message prioritization for real-time safety messaging

Real-time safety services rely on the exchange of messages to enhance the operations of connected and automated vehicles (CAVs). These safety messages convey vital information about traffic conditions, enabling drivers to take necessary measures to prevent accidents. The timely and reliable delivery of these messages is essential, necessitating efficient channel access. Vehicular Deterministic Access (VDA) is employed as a channel access scheme with distinct priorities and stringent timing guidelines, particularly for urgent safety warnings. In this paper, we propose a hybrid approach that combines VDA and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocols, along with a message prioritization algorithm, to ensure efficient and reliable communication of safety messages in vehicular networks. Our approach leverages the strengths of both VDA and CSMA/CA to avoid message collisions; VDA is more efficient under high traffic loads, while CSMA/CA is better suited for low traffic loads. Additionally, the incorporation of the message prioritization algorithm ensures strict deadline guarantees for high-priority messages, such as Decentralized Environmental Notification Messages (DENMs). We evaluate our proposed solution using the Artery simulation framework. Our results show over a 93% delivery rate for DENM exchanges while maintaining low collision probability across various traffic loads. This research provides practical guidance for the development of efficient and reliable communication systems for CAVs. It also offers a detailed analysis of the trade-offs among different access protocols and message prioritization strategies in vehicular networks.

Design study of gas-cooled fast reactor with natural uranium as fuel employing modified CANDLE shuffling strategy in the axial direction

Abstract This study investigated gas-cooled fast reactor performance utilizing natural uranium as the fuel employs modified constant axial shape of neutron flux, nuclide densities, and power shape during life of energy production (CANDLE) shuffling strategy in the axial direction. The performance has been carried out on a reactor with various power levels in the range of 2,700–3,100 MWt and refueling every 10 years of burnup. The main importance of the modified CANDLE (MCANDLE) is that it can utilize natural uranium as fuel without needs reprocessing or enrichment plant. During this work, the core has been partitioned into 10 regions of similar volume along the axial direction. The fuel was filled into the first region, then transported to the second region after 10 years of burnup, and then to the third region 10 years later. This technique was practiced to all 10 regions, and the fuel in the tenth region was discharged in the reactor core. 10 % of natural thorium, natural uranium and enriched nitride (15 N) were used as fuel input. The calculations were performed employing a standard reactor analysis code (SRAC). The collision probability method (PIJ) module of SRAC was used to calculate cell burnup, and the reactor core design calculations were done with the CITATION module of SRAC, which used JENDL-4.0 as a nuclear data library. The result shows that a high power level causes an increasing rate of burnup level and effective multiplication factor. The highest average discharge burnup level is about 31.3 % HM for case E and the lowest average discharge burnup is about 27.2 % HM for case A.

The bubble size produced in a pilot HydroFloat® cell and its effects on flotation

Unlike a traditional mechanical flotation cell, Eriez’s HydroFloat® is a fluidized-bed flotation device that can recover much coarser and less liberated particles. This is a new flotation machine where the effects of parameters such as bubble size are yet to be established. To address this problem, JKMRC has built a pilot HydroFloat® rig which it deployed to a copper–gold plant in New South Wales, Australia. Tests were performed at a range of operating conditions and bubble size images were collected and analysed using a novel newly created bubble size measurement method. In conventional flotation, a finer bubble size increases flotation rates because it increases the probability of bubble-particle collision and attachment. In this pilot HydroFloat® test program, however, flotation performance was optimal at an intermediate bubble size. Using the comprehensive test program data, the operating parameters that significantly affect bubble size were established, and an empirical model to predict bubble size was developed.