Spiral Concentrator Research Articles

The Use of Process Analysis and Simulation to Identify Paths to Improve the Operation of an Iron Ore Gravity Concentration Circuit

The processing of iron ore to recover the valuable iron oxide minerals is commonly carried out using spiral concentrators that separate valuable minerals from non-valuable ones on the basis of the specific gravity of minerals. This paper shows that the analysis of the operation of spirals should not only focus on the minerals (as it is usually the case), but should also consider the particle size of these minerals. Indeed, the sampling of two industrial iron ore circuits and the data processing of the resulting measurements show that unexpectedly about 10% of the coarse heavy iron oxide minerals are not recovered by the spirals of the two circuits. Tests conducted by an independent research center confirm this plant observation. The pilot plant tests also show that the wash water flowrate addition may adversely affect the recovery of coarse heavy mineral particles. A mathematical model for the spiral was implemented into a simulator for an iron ore gravity concentration circuit. The simulator shows a potential 0.7% increase of iron recovery by simply changing the strategy used to distribute the wash water between the rougher and the cleaner/recleaner spirals of the circuit. The simulator also shows that the introduction of a hydraulic classifier into the gravity concentration circuit yields a marginal improvement to the performances of the circuit.

Theory of oscillations performed by tools in spiral potato separator.

Theory of oscillations performed by tools in spiral potato separator.

Improving the Quality of Ferruginous Chromite Concentrates Via Physical Separation Methods

The low chromium-to-iron ratio of chromite ores is an important issue in some chromite deposits. The value of the chromite ore is indeed dictated in the market by its iron, as well as its chromium content. In the present study, a chromite concentrate was reprocessed by gravity (spiral concentrator) and magnetic separation to enhance the chromium-to-iron ratio. Also, detailed characterization studies including automated mineralogy were carried out to better understand the nature of the samples. Enhancing the chromium-to-iron ratio was achieved by using advanced spiral separators which will be discussed in this paper.

Improved zonal chondrocyte production protocol integrating size-based inertial spiral microchannel separation and dynamic microcarrier culture for clinical application

The zonal property of articular cartilage endows the tissue with biphasic mechanical properties to withstand shearing force and compressional loading. Current treatments for articular cartilage damage are not able to efficiently restore the zonal organisation and functionality. Size-based sorting of freshly isolated chondrocytes from full thickness (FT) cartilage using a spiral microfluidic device was shown to efficiently separate and enrich zonal chondrocytes. The translational application of this sorting protocol is challenging in the clinical setting due to the limited number of autologous chondrocytes from a patient. It is thus essential to explore the practicability of this sorting protocol on expanded chondrocytes. In this study, we first show that size-sorted zonal chondrocytes expanded on microcarriers in dynamic condition (dMC) were able to support comparable proliferation, while maintaining cell morphology, and the zonal cell size-phenotype relation, in contrast to expansion on a tissue culture plate. We further show that post-expansion size-based sorting can be applied on dMC-expanded FT chondrocytes, generating enriched zonal subpopulations that form phenotypically distinct cartilage constructs in the 3D hydrogel. This study demonstrates a novel scale-up zonal chondrocyte production protocol, incorporating size-based zonal chondrocyte separation and dMC platform, to maintain zonal chondrocytes’ phenotypes better to support zonal repair of articular cartilage.

Multi-objective optimization design of spiral demister with punched holes by combining response surface method and genetic algorithm

Spiral separator with punched holes was numerically analyzed and the correlation between structural variables and performance index was obtained based on the response surface method. Pitch, diameter, pipe length, and inlet velocity were selected as investigated variables, and the separation efficiency and pressure drop were chosen as objective functions. The results demonstrated that increasing the pitch or reducing the diameter results in greater separation efficiency. Pressure drop factor rises with the increase of vane diameter and the decrease of the pitch. Pitch, pipe length, and inlet velocity all have positive correlations with the separation efficiency. The optimization results were obtained by the Non-dominated Sorting Genetic Algorithm-II. These optimal points achieve greater separation efficiency and less pressure drop. Compared with original design, the separation efficiency of optimal point is enhanced by 1.92%–6.46%, while EU is reduced by 41.83%–58.18%. The maximal separation efficiency of optimal points achieves 0.99 with EU of 4.

Particle-laden thin-film flow in helical channels with arbitrary shallow cross-sectional shape

Particle-laden flows in helical channels are of interest for their applications in spiral particle separators used in the mining and mineral processing industries. In this paper, we extend the previous work of Lee, Stokes, and Bertozzi [“Behaviour of a particle-laden flow in a spiral channel,” Phys. Fluids 26, 043302 (2014)] by studying thin-film flows of monodisperse particle-laden fluid in helically wound channels of arbitrary centerline curvature and torsion and arbitrary cross-sectional shape. In the case where the particles are uniformly distributed through the depth of the film, significant analytic progress can be made yielding insight into the influence of channel geometry on particle distribution across the channel cross section: the governing equations reduce to a single nonlinear ordinary differential equation, which is readily integrated numerically to obtain the solution subject to appropriate boundary conditions. Motivated by possible application to the design of spiral separators, we consider the effects of changing the channel centerline geometry, the cross-sectional shape and the particle density on the resulting flows, and the radial distribution of particles. Our results support the findings in the work of Arnold, Stokes, and Green [“Thin-film flow in helically wound rectangular channels of arbitrary torsion and curvature,” J. Fluid Mech. 764, 76–94 (2015)] regarding the effect of channel centerline geometry and cross-sectional shape on flows in particle-free regions. In particle-rich regions, similar effects are seen although the primary velocity is lower due to increased effective mixture viscosity. Of key interest is the effect of channel geometry on the focusing of the particles for given fluxes of fluid and particles. We find that introducing a trench into the channel cross section, a feature often used in commercial spiral particle separators, leads to a smaller radial width of the particle-rich region, i.e., sharper focusing of the particles, which is consistent with experiments showing that channel geometry influences particle separation in a spiral separator.

Experimental modelling and plant simulation of spiral concentrators: Comparing response surface methodology and extended Holland-Batt models

Spiral concentrator and spiral plant modelling of chromite bearing ore is investigated in this paper. Spiral product stream responses (grade and recovery) were modelled according to variations in feed conditions (grade, density, flow rate) and primary splitter settings. The two modelling approaches constituted a quadratic response surface and an extension (to accommodate feed conditions) on the original Holland-Batt (1990) spline model. Additional validation of the extended Holland-Batt model behaviour was performed via regression on a second data set, based on hematite separation using spiral concentrators (Sadeghi, 2015). The quadratic model showed higher performance values on the training set; however, the extended Holland-Batt model showed better performance on the test data. Finally, both models were compared in terms of spiral concentrator plant modelling ability (based on an industrial spiral concentration plant). Quadratic response surface models were unable to produce acceptable grade-recovery curve simulations. The extended Holland-Batt model proved to be the superior spiral plant simulation model due to its ability to produce valid grade-recovery curves. The extended Holland-Batt spline-based model shows promise as an improvement over RSM for spiral modelling (and spiral plant simulation). The extended Holland-Batt model can provide the same screening, characterization and optimization functionality of RSM models for single-spiral experimental modelling, with the added benefit of simple extension to spiral plant simulation.

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.

Evaluation of Advanced Gravity and Magnetic Concentration of a PGM Tailings Waste for Chromite Recovery

This research was aimed at evaluating the efficiency of advanced gravity and magnetic separations on the recovery of chromite from the fine Platinum Group Metals (PGM) tailings consisting of particles 80% passing 75 µm with about 45% being >45 µm resulting in high chromite losses. The PGM plant tailings were subjected to X-ray fluorescence, scanning electron microscopy and particle size distribution analyses. The feed was then optimally classified with 60 mm diameter hydro-cyclone into underflow and overflow streams. The coarser underflow was further beneficiated using the spiral concentrator. The results obtained showed that the removal of fines increased the Cr2O3 grade for the spiral feed from 12.27% to 17.64% while spiral concentrate grade improved from 14.84% to 21.46% and recovery 69.85% to 95.53%. Magnetic separation efficiency was found to increase with particle size such that at >75 µm a concentrate with up to 17.13% grade and 61.5% recovery was achieved. The advanced Falcon concentration was also observed to be mainly particle size dependent and at 45 µm up to 17% grade and 60.3% recovery was achieved. The results obtained are based on particles >45 µm and the finer particles

New flotation flowsheet for recovering combustible matter from fine waste coking coal

Fine waste coking coal (FWCC) is a high-ash-content by-product produced in large quantities during separation of raw coking coal and deposited in open air without treatment, causing environmental hazards and energy waste. The main objective of this study was to recover clean coal with ash content less than 12.5% by reprocessing FWCC at KaiLuan (Group) Limited Liability Corporation (KLLC) via spiral separation, grinding, and flotation processes. First, the physical characteristics of FWCC were investigated using particle-size analyses, washability analyses, and polarizing microscopy. Then, a spiral separator was used to remove materials with high ash content from the FWCC. Subsequently, spiral clean coal was ground in a roll mill for different grinding durations. Finally, flotation separated the products of grinding from the clean coal. Analyses of the physical characteristics showed that the FWCC could be pretreated using gravity in a spiral separator because it had a large amount of high-density materials. 46.28% spiral clean coal with 26.50% ash content was obtained and 53.72% of spiral tailings with 68.94% ash content were removed with a spiral separator under optimal conditions. The following flotation theoretical yield of clean coal increases with the grinding time. However, flotation experiments show that the maximum actual yield of clean coal first increases and then decreases on increasing the grinding time from 3.5 min to 15 min. Approximately 50% clean coal was obtained at grinding times between 3.5 and 5 min. This can be used for metallurgical plants and has economic value. A novel gravity-grinding-flotation separation flowsheet was developed and nearly 24% of the FWCC could be translated into qualified clean coal to realize comprehensive utilization of this waste resource. Engineering practice further confirm that deep processing of FWCC could generate an extra profit of $11.846 million per year for KLLC. These results indicate that deep processing of FWCC is reliable, economical, and promising for the coking coal industry, and therefore, cleaner production of coking coal is feasible.

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.

Applications of Computer Simulation for Hydrodynamics of Multiphase Media in Studying Separation Processes in Mineral Dressing

The computing equipment of Computational Fluid Dynamics (CFD) for mathematical modeling of physics and physical chemistry in separation is presented. Completeness and particularization of the initial and boundary conditions in mathematical models condition validation and verification of the algorithm and results of computational experiments presenting the current state and evolution of a heterogeneous medium. There are three possible applications of the computational experiment in studying mineral dressing processes: investigation of operations in mineral processing machines; prediction of technological parameters in variation of separation modes and (or) retrofit installation; prototyping of new design equipment. The computer simulations of centrifugal classification, spiral separation, magnetic-and-gravity separation and flotation are discussed.

The Research of the Flow Characteristics in Spiral Membrane Separator

The spiral membrane separator is a novel module proposed for reducing the concentration polarization and membrane fouling of membrane separation process. This membrane separation process benefits from dean vortices produced by centrifugal instability in enhancing fluid mass transfer. A numerical stimulation of this membrane separation is presented and used to analyze the fluid flow characteristics and thoroughly understand the separation mechanism. The numerical model consists of a spiral flow path with rectangular sector. As the simulation with infiltration, the fluid domain of the ceramic membrane tube was as a porous medium domain. The standard momentum equation, added with the momentum equation source term which composed of the viscosity loss term and the inertia loss term, are figured out through the experimental characterization. In the simulation of spiral membrane separation, the Dean secondary flow structure is identified and found to enhance fluid mass transfer and to increase the permeate flux. The critical unstable state of spiral membrane separation is accordingly De=246 without the flow permeation and De=863 with the permeation, where Dean vortices cause collisions and the mixing of fluid particles. Then in the case of permeation, the fluid in separator at De=1232 is numerically simulated to show that the higher flow velocity and a large fluctuating trend of wall shear stress near the membrane surface (inside), which mainly contributed to alleviate concentration polarization and membrane fouling.

Theoretical studies of oscillations of the cleaning working bodies spiral potato separator

Purpose. Increase of efficiency of potato tubers cleaning process from impurities of new construction of spiral separator taking into account and activation of vibrating process of its cleaning spiral springs. Methods. The research was carried out with the use of higher mathematics, theoretical mechanics, elasticity theory and methods of programming and numerical calculations with the help of PC. Results. For the developed construction of the spiral separator of potato heap, which consists of cantilever mounted cleaning spiral springs, the mathematical model of free ends of spiral oscillations under the influence of external load is developed. An equivalent bending scheme of the cantilever spiral under the action of uniformly distributed load, selected corresponding axes of coordinates and parameters characterizing the vibrational process of the spiral end are determined. For such an equivalent scheme, a differential equation of cleaning spiral oscillations in partial derivatives is made for the first time. After the corresponding transformations, the differential equation was numerically solved according to the program, by means of a PC. This made it possible to find the dependence of the change in the winding pitch of the cleaning spiral spring as a result of its deformation, in particular, the simultaneous longitudinal stretching and transverse deflection, on its length. Also new analytical dependences of the reduced moment of inertia of the section of the cantilever spring are received, on the basis of which graphic dependences of change of its value on length of a spiral spring at the set diameter, pitch of skills, angle of rise of a coil and angular speed of rotation have been received on the PC. Conclusions 1.The calculated mathematical model of vibrations of the working bodies of the spiral separator of potato heap is constructed, as a result the differential equation of transverse bending vibrations of its console cleaning spiral spring is made. 2.On the basis of the differential equation solution of transverse bending oscillations of the cleaning spiral spring the analytical expressions describing the law of vibrational process and deflection of the spiral spring at any moment of time for any point of its longitudinal axis are received. 3.Analytical dependencies are obtained to determine the variable pitch of a curved coil spring at any given time and for any inter-turn lumen during this oscillatory process. 4.At the angular velocity of the spiral spring, which is equal to ω = 30 rad∙s-1, the density of the material of which the spring is made, = 7700 kg∙m-3, modulus of elasticity Е = 2∙1011 Pa, the radius of the bar = 8.5 mm, uniformly distributed spiral spring load by potato heap intensity 1000 Н∙m-1 the total spring deflection along its length varies from 0 to 0.25 m. 5.The obtained analytical expressions of restriction on the maximum change of the cleaning spiral spring pitch at its fluctuations from the condition that potato tubers do not fall into the spring inter-turn space taking into account structural and kinematic parameters of the cleaning spiral spring, the material from which it is made, technological modes of operation and tubers' sizes. 6.As the numerical calculations on the PC show, a cleaning spiral spring with the above parameters and an initial winding pitch S = 48 mm at the considered transverse oscillations at the expense of deformation can change a step up to 54 mm that will provide not falling out of a potato tuber outside of a separator of a potato heap. Keywords: potatoes, digging, impurities, cantilever spiral spring, oscillations, differential equation, numerical calculations on PC.

Numerical modelling of process of cleaning potatoes in spiral separator

Numerical modelling of process of cleaning potatoes in spiral separator

A study of the feasibility of upgrading rare earth elements minerals from iron-oxide-silicate rich tailings using Knelson concentrator and Wilfley shaking table

A number of gravity separation techniques for rare earth elements (REE) minerals have been investigated and reported in the literature. These include the use of dense/heavy media, Falcon concentrators, Knelson concentrators, spiral concentrators, laboratory scale jigs, and shaking tables. Most of these methods have provided considerable REE minerals recovery and upgrade; but remain at the laboratory testing stage. There are vast quantities of iron-oxide-silicate rich tailings (IST) containing low grade REE in Australia. This work is part of research and development studies currently underway at the University of South Australia to develop economically viable methods to exploit selected IST for their REE contents. In this investigation, the feasibility of exploiting the differences in specific gravity to concentrate REE minerals from a typical IST sample was studied using two gravity separation units, a Knelson concentrator (KC) and Wilfley shaking table. The feed sample and gravity separation products were characterised using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) to study and compare the performance of the KC and shaking table as gravity preconcentration methods. The results indicated that the performance of both the KC and shaking table are significantly dependent on the mineralogical and particle size characteristics of the feed, however, the tabling was found to be the preferred choice over the KC, due to its greater selectivity. Tabling of >38 μm feed samples produced the desired split between the iron oxides and silicate minerals. The results suggest that desliming of the feed to remove fine/ultrafine particles (<38 μm) prior to tabling is key to attaining the desired results with the shaking table. Overall, tabling produced appreciable REE minerals upgrade, with iron oxides occupying the bulk of the concentrates. The test results confirm the complex mineralogy of the IST, which compromised REE minerals upgrade. A modified concentration criterion expression which considers the liberation characteristics of minerals is proposed, which provides a better idea on the feasibility of gravity separation.

Rare-metal granites as a potential source of critical metals: A geometallurgical case study

Because of their low grades in critical metals such as Light Rare Earth Elements (LREE) or Sn, rare-metal granites are not considered as economic for metal recovery but, when altered, they are often exploited for their industrial minerals. The St Austell rare-metal granite is well known for its world-class kaolin deposits which formed as a result of the extensive weathering and alteration of the underlying granite. The St Austell granite body is composed of several granite components, each having its own accessory minerals assemblage. As a result of the kaolinisation process, some metal-bearing accessory minerals of the granite, such as monazite (LREE) or cassiterite (Sn), are partially liberated from the gangue which allow their pre-concentration in the micaceous residue which is considered as a potential source for critical metals recovery. Similarities with other similar rare-metal granites suggest that topaz granite is the most prospective for disseminated magmatic Sn-Nb-Ta-REE mineralization. However, comparison of the potentiality of 3 granite types i.e., biotite, topaz and tourmaline granites suggest that biotite granites is actually the most prospective due to higher degree of kaolinisation of the biotite granite which favour pre-concentration of its accessory mineral in the micaceous residue. In order to develop a geometallurgical framework for extraction of kaolin and metals from the selected granite component, a field sampling campaign is performed. Core samples are processed in the laboratory using a characterisation program that mimics the full-scale kaolin refining route. Two main products are recovered through this program, viz. MR180 (−180 +53 µm) and P5 (−5 µm), which correspond to a fine micaceous residue and a fine kaolin product respectively. These products are both analysed routinely for major and minor trace elements by XRF and yields are recorded to indicate process performance. A selected number of MR180 samples are also being characterised in terms of particle size by laser light scattering, geochemistry by ICP-MS, and mineralogy by QEMSCAN®. Comparison of characterisation results of MR180 samples and corresponding industrial residue samples shows a good correlation, suggesting that sample analyses are representative for the in-situ deposit and the processing behaviour. Monazite is found to be either fully liberated or fully locked from one sample to the other. Next, pilot-scale gravity concentration tests are performed on micaceous residue samples. Characterisation of the processing products shows that monazite lost in the tailings is mostly locked within tourmaline or micas and is fine grained. Then, predictive regression models for spiral separation performance in terms of recovery, product grade and enrichment as a function of the feed grade are developed for MR180 LREE grade data. Finally, kaolin resources can be classified using quantitative indicators such as yield of the P5 product and the iron oxides content which provides insight into the kaolin quality in terms of whiteness. This geometallurgical classification can be used to delineate zones of interest within the deposit. Although kaolin quality and recovery primarily inform extraction planning, zones which are also of interest for metal recovery can be identified. The proposed model predicts whether the expected LREE grade and recovery satisfy the by-product requirements.

Preliminary optimisation study on integrating mining with gravity separation

ABSTRACTOptimisation studies on integrating different procedures in mining and mineral processing have an increasing popularity in recent years, and most of them focus on the mine-mill or mine-flotation integration. However, few optimisation studies on integrating mining with gravity separation are found. The gravity separation plays a vital role in coal preparation, which also makes the related integration study necessary. In this work, an optimisation study on integrating mining with gravity separation is first carried out, which contributes to proposing the optimal cut point (the density at which 50% of the feed report to underflow) for gravity separation and the coal seam mass ratio for mining. Specifically, a simplified optimisation model includes separations in dense medium cyclones, dense medium shallow grooves, and spiral separators is developed. Then the Differential Evolution algorithm is employed to obtain the solution that has the maximum economic profit. Finally, the organic efficiency is utilised to evaluate this optimisation. The validation results indicate that the developed optimisation model and the adopted algorithm are applicable. Even though it is a simplified model, it is supposed to provide a preliminary optimisation scheme for integrating mining with gravity separation.

Теорія процесу очищення картоплі спіральним сепара­тором

Теорія процесу очищення картоплі спіральним сепара­тором

The beneficiation of tailing of coal preparation plant by heavy-medium cyclone

Dense-medium cyclones have been used for beneficiation of fine particles of coal. In this study, the usability of cyclones in the beneficiation of tailings of a coal preparation plant was investigated. For this purpose, separation tests were conducted using spiral concentrator and heavy medium cyclones with the specific weight of medium 1.3–1.8 (g/cm3) on different grading fractions of tailing in an industrial scale (the weight of tail sample was five tons). Spiral concentrator was utilized to beneficiate particles smaller than 1 mm. In order to evaluate the efficiency of cyclones, sink and float experiments using a specific weight of 1.3, 1.5, 1.7 and 1.9 g/cm3, were conducted on a pilot scale. Based on the obtained results, the recovery of floated materials in cyclones with the specific weight of 1.40, 1.47 and 1.55 g/cm3 are 17.75%, 33.80%, and 50%, respectively. Also, the cut point (ρ50), which is the relative density at which particles report equally to the both products are 1.40, 1.67 and 1.86 g/cm3. The probable errors of separation for defined specific weights for cyclones are 0.080, 0.085 and 0.030, respectively. Also, the coefficients of variation was calculated to be 0.20, 0.12 and 0.03. Finally, it could be said that the performance of a cyclone with a heavy medium of 1.40 g/cm3 specific weight is desirable compared with other specific weights.