Splitter Position Research Articles

Design of Experimental (DOE) Analysis of Silica Sand Processing Using Spiral Concentrator

The main aim of this study on silica sand using a spiral concentrator using the design of experiments DOE) approach is to improve the silica content of the tailing sand for the glassmaking process. Three significant operational parameters of the spiral concentrator, namely feed rate (t/h), solid feed (wt.%), and splitter position (cm), were investigated to observe their effects on the SiO2 grade (%) and recovery of SiO2 (%) in the middlings using Design of Experiments (DOE). The raw sample was sieved to prepare the feed sample in the size range of -600+75µm, which was the suitable particle size range for the glassmaking process. The SiO2 grade (%) of each middling fraction from 33 test runs was determined from XRF analysis. The analysis determined that the feed rate and weight of the solid feed (wt.%) significantly affected the separation, while the splitter position in the investigated range (4.5-5.5cm) showed a negligible effect on the percentage and recovery of SiO2 in the middling fraction. It was observed that a maximum SiO2 grade of 94.98% was achieved at a solid feed of 25%, feed rate of 0.63 t/h, and splitter position of 5.5cm. The highest SiO2 recovery of 89.74% was achieved at the solid feed of 15%, feed rate of 0.45t/h, and splitter position of 5.0cm. A trade-off between the optimized results for SiO2 Grade (%) and recovery of SiO2 (%) responses using overlaid contour plots suggested a feed rate of 0.58 t/h of feed rate and 25 wt. % solid feed regardless of the splitter position. The customized range of parameters is expected to produce 94.51% SiO2 grade (%) and 80.11% recovery of SiO2 in the middling fraction.

Characteristics of Combined-Cycle Inlet During Mode Transition in Off-Design State

Mode transition is essential for the combined-cycle engine inlet. During actual inlet operation, mode transition may occur in the off-design state. An experiment was performed with a generic over/under combined-cycle engine inlet mode to investigate the characteristics of the inlet mode transition in the off-design state. The transition Mach number was set to Mach 3.5 by design, while it was 2.9 during the experiment. Oscillatory flow is obtained during both down- and up-rotation processes of the splitter. Results show that the size and location of the separation bubble vary with the splitter position. The dominant frequency of the flowfield oscillation is always below 200 Hz. Combining the analysis of schlieren and dynamic pressure data, it is found that the main factor affecting the flowfield oscillation features is the self-excited oscillation of the shock train, while the acoustic resonance frequency is also reflected near the unstart point. Comparison of the pressure curves of the two processes shows that the hysteresis interval accounts for 17.8% of the entire rotation time of the splitter and that the hysteresis stems from the presence of the separation bubble on the splitter during the up-rotation of the splitter. The analysis of the unstart and restart points shows that they deviate from the isentropic and Kantrowitz limits, respectively. The new unstart and restart boundaries should consider the combined effect of the separation bubble at the duct entrance, the internal wave system, and the throat Mach number.

Design of partial cross-sectional geometry and prediction of separation performance in the spiral separator

ABSTRACT Understanding the influence mechanism of the partial cross-sectional geometry of a spiral separator on the flow field characteristics and particle separation performance is conducive to the design of a combined cross-section profile. The impact of the trough slope in the inner and middle troughs on the flow field characteristics and particle separation performance was investigated by CFD methods. The results show that the average depth of the flow film, the average tangential velocity, and the average radial velocity in the partial radial region are linearly related to the trough slope. With the increase in the trough slope in the inner and middle troughs (r = 30–110 mm), the radial velocity reversal position will decline, resulting in an enlarged proportion of the outward flow. Adjusting the trough slopes of the two straight segments in the inner and middle troughs will have a positive effect on the precise segregation of particles. In comparison, changing the trough slope in the middle trough containing the miscible band had a more significant effect on particle separation. A maximum separation efficiency of 80.80% was obtained with a trough slope in the middle trough of 5°and a splitter position of 95 mm.

CFD investigation of flow through a centrifugal compressor diffuser with splitter blades

The aerodynamic losses in centrifugal compressors are mainly associated with the separated flow on the suction sides of impeller and diffuser vanes. The overall performance of such compressors can be improved by adding splitter vanes. The present work examines the effect of varying the geometrical location of the splitter vanes in the diffuser on the overall performance of a high-speed centrifugal compressor stage of a small gas turbine. To increase the pressure recovery through the diffuser, two radial sets of vanes are used. The first set of vanes (diffuser-1) is equipped with splitter vanes, placed mid-distance between the main vanes, while the vanes of the second set (diffuser-2) are conventional vanes. Flow through the compressor was simulated using the ANSYS 19 workbench program. Flow characteristics and compressor performance were obtained and analyzed for different circumferential positions of the splitting vanes relative to the main vanes of diffuser-1. The study covered seven positions of the splitter vanes including the original design of the diffuser where the splitter vanes were located at mid-distance between the main vanes. The analysis shows that, at design conditions, selecting the position of the splitter vanes to be nearer to the pressure side of the main vanes improves the stage performance. In the present study, locating the splitters at 33% of the angular distance between the main vanes leads to the best performance, and a significant improvement in the overall stage performance is recorded. The pressure recovery coefficient is raised by about 17%, the pressure ratio is increased by about 1.13%, and the stage efficiency is increased by about 2.01%, compared to the original splitter position. Performance improvement is related to the suppression of the flow separation and the more uniformity of flow. On the contrary, further moving the splitter closer to the main blade, the pressure recovery coefficient is decreased by about 2% than the position of 33% of the angular distance, but still higher than the original position by about 15% and a limited improvement in the compressor performance is noticed. Moving the splitter far out the main blade annihilates the static pressure recovery of the diffuser by about 2:7% compared with the original position. So, for the investigated compressor, the best position of the splitter blade in the circumferential direction, which provides the best stage performance in our parametric analysis, is not necessary to be at the mid-angular distance between the diffuser’s main blades, but it is achieved by moving the splitter to about 33% of the angular distance where the diminished loss from the suppressed flow separation is more prevailing and the instigated friction losses from splitter surfaces are less critical.

Free energy-extraction using Savonius hydrokinetic rotor with dual splitters

Hydrokinetic energy is a broadly available form of low-grade energy in countries like India, where irrigation canals are available in huge areas. To utilize this energy, hydrokinetic turbines are used. Out of many hydrokinetic turbines, efforts are made to improve Savonius hydrokinetic turbine's performance in the present work. The Savonius rotor profile is modified by providing a dual splitter-like shape on the blade's concave side. The two cases were selected for finding the optimum splitter position of both the splitter. The upper (top) splitter kept fixed and radially placed the second splitter in the first case. In the second case, the lower (bottom) splitter fixed and moving another splitter radially. Validated Computational analysis was done to analyze performance after modification. The fluid material was taken as water with standard properties. The improvement was observed for the specific position of splitters by 7.3% from conventional design.

Modeling and Optimisation of Spiral Concentrator for Beneficiation of Iron Ore Slimes from Kirandul, India

Experiments were carried out using a spiral concentrator test rig containing feed conditioner, centrifugal pump and a spiral concentrator with feed to spiral and recirculation. Time samples of concentrate and tails were collected, weighed, dried analysed. Regression equations were developed for Concentrate yield, grade and percent recovery of iron values using Box Behnken Model and Minitab 19 software. The optimised yield, grade and percent recovery are 69.98, 64.98 and 79.20 against the target values of 70.00, 65.00 and 80.00 respectively at 16.00% solids, 2.20 m3/h feed rate and 14.40 cm splitter position. Surface (wire mesh) plots were drawn using Minitab 19 to explain the relation between independent variables and response variables. Maximum yield predicted was 80.24% by weight at a feed consistency of 20.00% solids, feed rate of 1 m3/h and at a splitter position of 16.00 cm whereas the minimum yield predicted was 17.19% by weight at a feed consistency of 30.00% solids, feed rate of 3 m3/h and splitter position of 12.00 cm. Maximum grade predicted was 68.73%Fe at a feed consistency of 30% solids, feed rate of 1.00 m3/h and splitter position of 12.00 cm, whereas the minimum grade predicted was 61.03%Fe at a feed consistency of 10% solids, feed rate of 1 m3/h and splitter position of 16.00 cm. The maximum percent of iron values recovery predicted was 86.19 at a feed consistency of 20.00% solids, feed rate of 1.0 m3/h and splitter position of 16.00 cm whereas the minimum recovery predicted was 18.82% at a feed consistency of 30% solids, feed rate of 3 m3/h and splitter position of 12.00 cm. Surface plots were used to explain the variation in response variables concentrate yield, grade and recovery of iron values.

Separation of the coal-quartz mixture using tribo-electrostatic separator: Effect of surface pretreatment

The present study illustrates the effect of physical (thermal) and chemical surface treatment on the separation of the coal-quartz synthetic mixture in a tribo-electrostatic separator. The work also reports the effect of applied voltage and splitter position on the tribo-electrostatic separation of surface treated and untreated samples. Different reagents used in chemical conditioning of the synthetic mixture are kerosene, acetic acid, acetone, ethanol, phenol, toluene, and aniline. The study establishes that both chemical and heat treatment improves the tribo-electrostatic separation efficiency of coal and quartz particles. The applied voltage and splitter position affect the product grade and yield of treated and untreated samples. The ash removal and combustible separation efficiency of the synthetic mixture improved after chemical conditioning of the synthetic mixture with ethanol, acetone, acetic acid, and aniline. However, aniline treatment has produced the best separation result. It is possible to achieve 9 and 14% ash clean coal with 40% yield each from 53% ash synthetic mixture at 15 kV applied voltage after aniline and heat treatment, respectively. The ash removal and combustible separation efficiency of the tribo-electrostatic separator for the aniline and heat-treated synthetic mixture are 96, 60% and 90, 70%; respectively.

Application of Artificial Neural Networks to Predict Dry Magnetic Separation of Low-Grade Hematite Fines

An artificial neural network model to predict the performance of induced roll high-intensity magnetic separator while upgrading low-grade iron ore fines is presented in the present investigation. Key process parameters of induced roll magnetic separator operation, i.e., applied current, speed of rotor, splitter position, particle size, and feed rate, are used as the network input. A feedforward ANN is designed with one hidden layer, with units varying from 9 to 40 and capable of estimating the separation performance (iron content, silica content, iron recovery, and silica rejection of the magnetic product) in an induced roll magnetic separator. Simulated results obtained using the neural network modeling correspond closely to the actual results with a correlation of coefficient (R2) > 0.95 in training and testing stages. The developed models are further used to understand the sensitivity of the studied variables. The effects of speed of the rotor and splitter position are found to be more sensitive to the separation. Furthermore, an optimized solution is designed to predict the best achievable grade-recovery curve for this pre-concentration.

Electrostatic separation of aluminium from residue of electric cables recycling process

Cables and wires have a widespread use due to their application in electric power and data transmission. Since they consist of a conductive core (Cu or Al) and an insulating layer (polymer), they can be brought back to life after disposal through recycling in the form of secondary raw materials such as copper, aluminium and/or polymer. The aim of this paper is to research the possibilities of electrostatic separation use for separating aluminium left in residue fraction after the process of recycling Al waste electric cables, as well as to determine the influence of operating parameters and the optimal separation conditions. Waste fraction characterisation has determined that aluminium is mainly found in small–size particles (<2 mm) with the mass fraction higher than 60%. During the research planning the central composite design was used and three operating variables of an electrostatic separator were tested: roll speed, voltage and separation splitter position. Results have shown that it is possible to obtain a concentrate with the Al mass fraction of 97.86% at 91.20% recovery. It has been shown that the splitter position has the most significant influence on the grade of concentrate and recovery. It has also been shown that the roll speed individually and the interaction of the roll speed and splitter position have a significant influence on the grade of concentrate.

Upgrading a manufactured fine aggregate for use in concrete using dry rare-earth magnetic separation

Manufactured fine aggregates are progressively more used worldwide as an alternative to natural sand in concrete. In a recent study by the authors the removal of contaminants from manufactured fine gneiss aggregates by dry rare-earth magnetic separation was investigated. The present work initially demonstrates that single-stage dry high-intensity magnetic separation of the unclassified fine fraction (−2.36 mm) of the aggregate produced by a vertical shaft impact crusher allows simultaneous partial removal of the flaky biotite particles as well as reduction in the proportion of fines, thus improving its potential for application as a replacement of natural sand in concrete. The work then investigates the effect of magnetic field intensity, specific throughput, roll velocity, splitter position and moisture content on the performance of a bench-scale separator following a full factorial design of experiments. The non-magnetic product from an additional test was then used in combination with the coarser (+2.36 mm) unconcentrated fraction produced by a vertical shaft impact crusher in tests in concrete. Concretes with different strengths were prepared and results show that the upgraded non-magnetic manufactured aggregate was able to match the performance of concrete using natural sand, demanding one third less rheology additive, with comparable strengths at 28 days of curing.

Enhanced gravity particle classifier: Experiments with 3D printed device and computational fluid dynamics simulations

AbstractCentrifugal force developed in a fluid flow through closed spiral channel produces enhanced gravity environment to facilitate particle classification. The novel design is inspired by open channel spiral concentrators that are used in mineral processing industries. The concept is initially validated through computational fluid dynamics (CFD) simulations. Preferential movement of coarser particles, which experience greater centrifugal force, to the outer periphery was observed. These predictions are validated by conducting experiments on a 3D printed spiral classifier. The CFD simulations compared well with observed experimental separation function. The model was further used to conduct parametric study of various design and operational parameters. Simulations reveal that the cut‐size could change from 8 μm to 260 μm depending on the splitter position. The novel device will allow a direct and online control of cut size/density when suitably enhanced with required mechanisms.

Performance evaluation of a laboratory floatex density separator and its comparison with a spiral concentrator

ABSTRACT Two different samples were collected from the Beneficiation Plant (BP) for detailed studies. Sample I and Sample II are the feeds to the spiral concentrator from an existing beneficiation circuit of BP at JSW steel with two different size fractions of −1 mm + 150 µm assaying 53.26% Fe, 13.94% SiO2, 6.88% Al2O3 and −150 µm assaying 51.7% Fe, 17.4% SiO2, 4.3% Al2O3, respectively. The samples consist of hematite as the major iron-bearing mineral and goethite as the minor iron-bearing mineral. In both sample it was found that interlocked phases of hematite with gangue minerals like koalinite, quartz etc in varying proportion. Laboratory trials have been carried out using FDS by varying the teeter water flow rate and bed height set point at constant feed flow rate. For the spiral concentrator the feed rate, slurry density and splitter position were varied. Test results indicated that FDS was highly selective in rejecting siliceous and aluminous gangue from iron ore compared to the spiral concentrator.

Electrostatic Separation of Copper and Glass Particles in Pretreated Automobile Shredder Residue

There is increasing demand for an efficient technique for separating automobile shredder residue (ASR) obtained from end-of-life vehicles (ELVs). A particular challenge is the physical separation of conductive materials from glass. In this study, the performance of pretreatment and induction electrostatic separation process was evaluated. The results show that a sieving/washing (combination of sieving and washing) pretreatment was the most effective for removing conductive material compared to electrostatic separation alone. The optimum separation efficiency of copper products was achieved with an applied voltage of 20 kV, a relative humidity of less than 35%, and a splitter position of 8 cm. Although the separation efficiency was slightly reduced when some small glass particles remained attached to the conductive materials, the separation efficiency of copper from the pretreated ASR dramatically increased to 83.1% grade and 90.4% recovery, compared to that of raw ASR (34.3% grade and 58.6% recovery). Based on these results, it was demonstrated that the proposed sieving/washing pretreatment was proficient at removing conductive materials from glass; thus, it has the potential to significantly improve the efficiency of electrostatic separation for ASR.

Spiral Concentrator Interface Monitoring Through Image Processing: A Statistical Learning Approach

Spiral concentrators are robust gravity separation devices that allow for concentration of slurry streams. Optimal splitter position (which determines recovery and grade) is dependent on the interface positions of the concentrate, middlings and/or tailings in the trough. Various image processing techniques have been proposed to automatically detect interface positions, which could be useful for spiral concentrator monitoring and control. Two methods are compared in this work: the first is the previously-described genetic algorithm optimization of the parameters of a traditional edge detection algorithm. The second uses logistic regression, a well-known statistical classifier. The performance of the two methods was compared on two data sets, for ilmenite and chromite concentration. The logistic regression method was shown to outperform the genetic algorithm approach, in terms of computational cost of training and successful interface detections on test data, for both the relatively easy ilmenite concentrate interface, and the more challenging chromite concentrate interface.

Centrifugal Compressor Performance Improvements Through Impeller Splitter Location

The splitter blades are very common to use for centrifugal compressor impellers to improve the compressor performance and manufacturing capability. In this study, a low-flow single-stage centrifugal compressor with a vaneless diffuser was used to investigate the location effects of the impeller splitter between two main blades. It is demonstrated that the splitter position provides an opportunity to improve the compressor performance and reduce the operational cost. The splitter location optimizations were performed numerically, and the optimal splitter location was identified. A prototype was built for the impeller with optimal splitter position. The performance tests were performed, and test results are compared with numerical analyses. The studies indicated that splitter positions have impacts on the compressor stage performances. The studies showed that the traditional splitter located in the middle of the two main blades is not the optimal location for aerodynamic performance. The splitter location optimization provided the opportunity to improve the centrifugal compressor performance further.

Influence of particle size on dry high-intensity magnetic separation of paramagnetic mineral

Dry high-intensity magnetic separators are one of the most common magnetic separation methods extensively used for the concentration of paramagnetic minerals based on their magnetic susceptibility, particle size, particle density, and shape. In this paper, the influence of particle size on the separation of the garnet particle in Induced Roll Magnetic Separator (IRMS) was investigated by varying the magnetic field intensity, rotor speed, feed rate, and splitter position. The influence of particle size on a magnetic fraction of Induced Roll Magnetic Separator was analysed as the D50 (μm) and D80 (μm) size. The results show that segregation of the coarser particle is segregated in non-magnetic fraction while finer sized particles are at the magnetic fraction. To understand further, particle size distribution is analysed by Rosin-Rammler equation and the variation of the constants are explained by statistics. Also, the influence of individual variables and their interactions on the segregation pattern is described by analysis of variance method along with response surface plots.

Enhancement of Iron Recovery from Steelmaking Slag Fines by Process Optimization of Upgrading the Slag Fines with Dry Magnetic Separation

Steelmaking slags are usually processed for iron recovery by dry magnetic separation. The recovered iron-rich products are recycled back into the ironmaking and steelmaking processes to replace high-cost steel scrap and iron ores. However, current slag processing is far away from optimum conditions, especially for slag fines with small particle sizes, resulting in generation of nonrecyclable “metallic” slag fines with insufficient iron content and great iron loss in “nonmetallic” slag fines with excessive iron content. In this research, the authors aimed at enhancing iron recovery from the steelmaking slag fines by process optimization of upgrading the slag fines with dry magnetic separation. The key operating parameters considered in the upgrading process included magnetic drum radius, drum rotation speed, surface magnetic field strength, gradient of the field strength, and splitter position. The first four operating parameters were first combined into a compound variable which represents separation capability (SC) of a magnetic drum separator. Effects of separation capabilities and splitter positions on the separation of steelmaking slag fines were then tested on five different samples of steelmaking slag fines. At last, optimization of the upgrading process on a pilot magnetic drum separator was conducted to maximize recycling ratio of the steelmaking slag fines by adjusting SC and splitter position of the magnetic drum separator.

Results of foreign bodies removal from the posterior eyeball segment by transvitreal approach

Purpose. To investigate transvitreal intraocular foreign body (IOFB) removal results, and to determine indications for this splinter removal approach. Materials and methods. A chart analysis of 35 cases with splinter eye trauma was carried out. In all patients, a pars plana vitreoretinal surgical procedure was performed to remove the IOFB. Results. The intraocular penetration of foreign body was accompanied by injuries of different eyeball structures, which presented as intravitreal hemorrhage, hyphema, subretinal bleeding, retinal detachment, traumatic cataract, iridocyclitis. Splitter removal was complemented by endolaser coagulation; scleroplastic component and gaz-fluid exchange. In 54.29% patients with trauma, a lensectomy had to be added to the vitrectomy with IOFB removal. As a result of treatment, visual acuity increased in 51.43% injured patients. In the late post-operative period, retinal detachment developed in 14.29% of cases. Conclusions. IOFB removal by transvitreal approach is recommended in intravitreal, pre- or intraretinal splitter position; in retro-equatorial foreign body localization; when intraoperative splitter visualization is possible; in posterior vitreous detachment formation.

Numerical Simulation of Asymmetric Merging Flow in a Rectangular Channel

The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of the splitter plate was taken as a centreline of channel but here it is considered its different positions which cause the asymmetric behaviour of the flow field. The geometric parameter that controls the position of splitter is defined as splitter position parameter a. The plane Poiseuille flow is considered far from upstream and downstream of the splitter. This flow-problem is solved numerically by a numerical scheme comprising a fourth order method, followed by a special finite-method. This numerical scheme transforms the governing equations to system of finite-difference equations, which are solved by point S.O.R. iterative method. In addition, the results obtained are further refined and upgraded by Richardson Extrapolation method. The calculations are carried out for the ranges -1 α R 5. The results are compared with existing literature regarding the symmetric case (when a = 0) for velocity, vorticity and skin friction distributions. The comparison is very favourable. Moreover, the notable thing is that the decay of vorticity to its downstream value takes place over an increasingly longer scale of x as R increases for symmetric case but it is not so for asymmetric one.

Spiral Concentrator Interface Monitoring through Image Processing: Optimization for Parameter Selection

Abstract: Spiral concentrators are robust gravity separation devices that allow the concentration of slurry streams in terms of a desired mineral of interest. The optimal splitter position in a spiral concentrator is dependent on the interface position(s) between concentrate, middlings and/or gangue streams in the spiral trough. Image processing methods can be used to detect interface positions, which could be used in spiral concentrator operation monitoring and control. However, the algorithms required for interface monitoring by means of image processing involve a large number of parameters that must be specified. Such parameter specification can become onerous if done on a manual or ad hoc basis. The goal of this study is to investigate the potential of applying an optimization approach to determine optimal parameters for interface detection through image processing. Results are promising, indicating good interface detection, even for small training data set sizes (e.g. 50 images).