Volumetric Solids Concentration Research Articles

Solid-liquid mass transfer in sonicated agitated vessels with high concentration slurries

Process intensification of agitated slurry vessels requires improving solid-liquid mass transfer beyond that can be achieved with agitation alone. As ultrasound has been shown to enhance solid-liquid mass transfer, this study aims to investigate whether process intensification can be achieved under combined (agitation + ultrasonic irradiation) condition. Experiments were conducted involving high volumetric solids concentration (C V ) suspended at just off-bottom solids suspension (N JS ) condition in a 0.2 m diameter tank equipped with a turbine and an ultrasonic generator. The mass transfer experiments were conducted using ion-exchange (NaOH-cation resin) and desorption (phenol-polymeric resin) systems. Ultrasound was found to have no influence on mass transfer in the ion-exchange system for a C V range of 0.030.20 (volume solids/volume slurry). However, the rate and degree of mass transfer in the desorption system were higher under the (agitation + ultrasonic irradiation) condition compared to those under agitation-only condition. Under ultrasound irradiation, the degree of mass transfer in the desorption experiments increased with increasing time but did not show a clear trend with increasing C V . These results imply that the level of enhancement in solid-liquid mass transfer in agitated vessels due to ultrasound is dependent on the physical properties of the solid and liquid phases as well as C V .

A laboratory experience on the effect of grains concentration and coarse sediment on the rheology of natural debris-flows

Not only solid volumetric concentration, but also coarse particle content play a relevant role on the rheology of soil mixtures involved in mud, debris, hyper-concentrated and earth flows. This paper is devoted to investigating the influence of bulk solid volume concentration and of coarse fraction on the rheological behavior of granular slurries. Laboratory activity is carried out involving different soils from the source area of real debris flows (from the Campania region in Italy). Experimental results demonstrate that the flowing behavior is the same as yield stress fluids with a static yield stress value larger than the dynamic one. A generalized Herschel–Bulkley model is considered, accounting for a consistent index which is a function of solid volume concentration. Experimental evidence demonstrates that the viscous characteristics (i.e., yield stresses and bulk viscosity) are very sensitive to coarse grain content, and the flow characteristics are deeply affected by small variations of both solid content and particle size. In effect, the tested materials show increasing yield stress (both static and dynamic) with solid concentration and decreasing yield stress for an increment of coarser solid fraction. To the contrary, assuming a constant fine grain relative content, the higher the coarse grain fraction is, the lower the yield stress results. Moreover, the typical transition from solid-like to fluid-like behavior, and vice versa, is strongly influenced by solid concentration and grain size distribution.

A New Technique to Predict In Situ Stress Increment Due to Biowaste Slurry Injection Into a Sandstone Formation

Underground injection of slurry in cycles with shut-in periods allows fracture closure and pressure dissipation which in turn prevents pressure accumulation and injection pressure increase from batch to batch. However, in many cases, the accumulation of solids on the fracture faces slows down the leak off which can delay the fracture closure up to several days. The objective in this study is to develop a new predictive method to monitor the stress increment evolution when well shut-in time between injection batches is not sufficient to allow fracture closure. The new technique predicts the fracture closure pressure from the instantaneous shut-in pressure (ISIP) and the injection formation petrophysical/mechanical properties including porosity, permeability, overburden stress, formation pore pressure, Young's modulus, and Poisson's ratio. Actual injection pressure data from a biosolids injector have been used to validate the new predictive technique. During the early well life, the match between the predicted fracture closure pressure values and those obtained from the G-function analysis was excellent, with an absolute error of less than 1%. In later injection batches, the predicted stress increment profile shows a clear trend consistent with the mechanisms of slurry injection and stress shadow analysis. Furthermore, the work shows that the injection operational parameters such as injection flow rate, injected volume per batch, and the volumetric solids concentration have strong impact on the predicted maximum disposal capacity which is reached when the injection zone in situ stress equalizes the upper barrier stress.

Backfilling performance of mixtures of dredged river sediment and iron tailing slag stabilized by calcium carbide slag in mine goaf

Re-utilization of industrial wastes or by-products in construction, including dredged river sediments (DRS), iron tailing slag (ITS) and calcium carbide slag (CCS) etc., can reduce the construction cost, decrease the storage requirement and also be of great benefit to the environment. In this research, the aforementioned wastes (i.e., DRS, ITS and CCS) were synthetically recycled and used as the backfilling materials in the mine goaf to solve the problem of subsidence. Systematic laboratory experiments were conducted to ensure that these recycled materials can fulfill the requirement on the slump value and unconfined compressive strength after 7-day’s curing. The results show that despite that Ordinary Portland cement (OPC) suppresses the slump value, CCS elevates the flowability, and then the maximal flowability is achieved when the mass ratio of DRS to ITS was 70:30 with a cement content of 16.7%. ITS addition into DRS upgrades the strength of the mixtures of DRS and ITS stabilized by OPC and CCS for the skeleton effect and water content reduction. The optimal proportion between DRS, ITS, OPC and CCS in this case is 60:40:16:4 in mass, with a slump value of about 160, and unconfined compression strength after 7-day’s curing about 2.8 MPa. At last, a simple expression to predict the strength of the backfilling materials was proposed referring the gel-space theory and the concept of volumetric solid content, where just two variables (i.e., the binder content and the volumetric solid content) can characterize this complex matrix.

On developing improved modelling for particle velocity and solids friction for fluidized dense-phase pneumatic transport systems

Pneumatic transport of fine powders in fluidized dense-phase pneumatic conveying of powders has become popular in several industries because it offers various advantages, such as reduced air flow and gas velocity, reduced pipeline sizing and wear rate, reduced size requirement of gas–solid separator unit etc. For the reliable design of a pneumatic conveying system precise estimation of the solids friction factor through horizontal straight pipes is essential, but it is a challenging task till date because of the highly concentrated, turbulent, and complex nature of the gas–solids mixture. In the present work, power station fly ash (median particle diameter: 22 μm; particle density: 2370 kg/m3; loose-poured bulk density: 660 kg/m3) and cement (median particle diameter: 19 μm; particle density: 2910 kg/m3; loose-poured bulk density: 1080 kg/m3) were conveyed through different pipeline configurations (i.e., 65-mm inner diameter × 254-m-long and 80/105-mm inner diameter × 407-m-long step-up pipeline). For the fluidized dense-phase flow in pneumatic conveying system, governing equations were developed and the same were solved using fourth-fifth-order Runge-Kutta-Fehlberg (RKF45) method. The results revealed that the particle velocity and actual gas velocity and the ratio of the two velocities increases along the direction of flow, while an opposite trend was found for the solids volumetric concentration. The particle velocity and actual gas velocity terms were then included in an existing pure dilute-phase model (for solid friction factor) to modify it, by incorporating sub-models for particle and actual gas velocities and impact and solids friction factor and make it suitable for dense-phase mode. The solids friction-factor model was then validated by comparing the experimental and predicted pneumatic conveying characteristics for different solids flow rates and by using it to predict the total pipeline pressure drops for larger and longer pipelines. The new model has shown reliable predictions in the dense-phase region.

Effect of excess pore pressure on the long runout of debris flows over low gradient channels: A case study of the Dongyuege debris flow in Nu River, China

Debris flows with long reaches are one of the major natural hazards to human life and property on alluvial fans, as shown by the debris flow that occurred in the Dongyuege (DYG) Gully in August 18, 2010, and caused 96 deaths. The travel distance and the runout distance of the DYG large-scale tragic debris flow were 11km and 9km, respectively. In particular, the runout distance over the low gradient channel (channel slope<5°) upstream of the depositional fan apex reached up to 3.3km. The build-up and maintenance of excess pore pressure in the debris-flow mass might have played a crucial role in the persistence and long runout of the bouldery viscous debris flow.Experiments to measure pore pressure and pore water escape have been carried out by reconstituting the debris flow bodies with the DYG debris flow deposit. The slurrying of the debris is governed by solid volumetric concentration (SVC), and the difference between the lower SVC limit and the upper SVC limit can be defined as debris flow index (Id). Peak value (Kp) and rate of dissipation (R) of relative excess pore pressure are dependent on SVC. Further, the SVC that gives the lowest rate of dissipation is regarded as the optimum SVC (Cvo). The dissipation response of excess pore pressure can be characterized by the R value under Cvo at a given moment (i.e., 0.5h, 1h or 2h later after peak time). The results reveal that a relatively high level of excess pore pressure developed within the DYG debris-flow mass and had a strong persistence capability.Further research shows that the development, peak value and dissipation of excess pore pressure in a mixture of sediment and water are related to the maximum grain size (MGS), gradation and mineralogy of clay-size particles of the sediment. The layer-lattice silicates in clay particles can be the typical clay minerals, including kaolinite, montmorillonite and illite, and also the unrepresentative clay minerals such as muscovite and chlorite. Moreover, small woody debris can also contribute to the slurrying of sediments and maintenance of debris flows in well vegetated mountainous areas and the boulders suspended in debris flows can elevate excess pore pressure and extend debris-flow mobility.The parameters, including Id, Kp, R and etc., are affected by the intrinsic properties of debris. They, therefore, can reflect the slurrying susceptibility of sediments, and can also be applied to the research on the occurrence mechanisms and risk assessment of other debris flows.

Influence of crystal growth kinetics on prediction of macro segregation by micro-macroscopic simulation of binary alloy solidification

Using the micro-macroscopic computer simulation model of binary alloy solidification, based on a single domain control-volume calculations, and involving the tracking of columnar dendrite tips envelope for distinguishing different grain structures within the two-phase liquid-solid region, the paper reports the outcomes of the detailed analysis addressing the question of the influence of enhanced KGT crystal growth models on the predicted macro-segregation pattern in the Al-4wt.%Cu alloy cast. In particular, the analysis concerns the impact of a proper selection of the stability constant for the KGT model (based on a crystal-melt surface energy anisotropy strength and linear scaling law of the marginal stability theory) on the predicted dendrite tip under-cooling, volumetric solid fraction and actual solute concentration along the front of columnar dendrite tips. Differences in the resulting evolution of both: the under-cooled melt region within the mushy zone and the solute concentration fields calculated for the considered various kinetics of a grain growth are also reported and discussed.

Sedimentation of solids in drilling fluids used in oil well drilling operations

Petroleum stands out as an important energy source. In oil well drilling operations, drilling fluids are used with the main purpose of cleaning and maintaining the hydrostatic pressure in the wellbore. Due to the importance of understanding solid-fluid interaction and the lack of quantitative studies on solids content in regions with high solids concentrations, this study evaluated the stability of drilling fluids. Rheological tests and gravitational and batch sedimentation tests with fluids differentiated by the addition of calcium carbonate assessed the separation dynamics as a function of time and position and determined the constitutive equations for pressure on solids, which are fundamental to solve models of flow through porous media. Gamma-ray attenuation, a non-destructive technique, quantified the local volumetric solids concentration in sedimentary regions. The results showed a shear-thinning behavior and thixotropic effects in the fluids and the influence of calcium carbonate on the sedimentation profile. The non-thickened suspension had lower values of apparent viscosity, higher sedimentation rates, and more compressible sediments than the thickened system. Thus, the formulation of drilling fluids affected the separation process in suspensions; for that reason, it must be adjusted to the operational conditions. This study contributed to increase rheological and stability knowledge on non-Newtonian suspensions.

Dependence of Sediment Suspension Viscosity on Solid Concentration: A Simple General Equation

In this study, a simple and new parametric equation is proposed that describes the relative viscosity of a suspension as a function of suspended solid concentration, covering a range from very dilute to highly concentrated states, based on Costa (2005). The proposed viscosity law depends mainly on the solid volumetric concentration and maximum packing fraction at which a regime transition occurs. Furthermore, the viscosity of dilute as well as a highly-concentrated kaolinite suspension (in excess of 40% and lower than 50%) was measured in a coaxial cylinder rheometer. The proposed formula shows a capability of fitting the measured bulk viscosity into the hyper-concentrated regime in the experiment. Finally, the proposed equation could also be found to show a good fitting relationship with published experimental results on partially crystallised Li2Si2O5 melt and partially melted granite with solid contents from 75% to 95%.

Enhancing Impeller Power Efficiency and Solid–Liquid Mass Transfer in an Agitated Vessel with Dual Impellers through Process Intensification

The effects of high volumetric solids concentration (CV), impeller type, and baffles on the impeller power input required for solids suspension and dispersion and the solid–liquid mass transfer coefficient (kSL) were studied in this work using an agitated vessel with dual impellers for the purpose of process intensification. It was found that at CV = 0.2 (v/v), the impeller power consumption required for solids suspension per unit mass solids (eJS = PJS/MS) is minimized while at the same time achieving maximum kSL values. Overall, it was observed that process intensification could be achieved using two radial flow impellers in a taller vessel under unbaffled conditions. A case study highlighting the benefits of adopting some of this study’s recommendations is presented. Mathematical correlations proposed to estimate eJS, impeller power consumption for solids dispersion, and kSL as a function of CV were found to fit experimental data reasonably well.

Numerical simulation of fluidized dense-phase pneumatic conveying of powders to develop improved model for solids friction factor

Accurate prediction of the solids friction factor through horizontal straight pipes is important for the reliable design of a pneumatic conveying system, but it is a challenging assignment to date because of the highly concentrated, turbulent, and complex nature of the gas–solids mixture. Power-station fly ash was transported through different pipeline configurations. Numerical simulation of the dense-phase pneumatic conveying systems for three different solids and two different air flow rates have shown that particle and actual gas velocities and the ratio of the two velocities increases in the flow direction, whereas the reverse trend was found to occur for the solids volumetric concentration. To develop a solids friction-factor model suitable for dense-phase flow, we modified an existing pure dilute-phase model by incorporating sub-models for particle and actual gas velocities and impact and solids friction factor. The solids friction-factor model was validated by using it for scale-up predictions for total pipeline pressure drops in longer and larger pipes and by comparing experimental and predicted pneumatic conveying characteristics for different solids flow rates. The accuracy of the prediction was compared with a recently developed two-layer-based model. We discussed the effect of incorporating the particle and actual gas velocity terms in the solids friction-factor model instead of superficial air velocity.

Experimental correlation of gas–liquid–solid mass transfer coefficient in a stirred tank using response surface methodology

In this paper, the three-phase (gas–liquid–solid) system in a stirred tank is experimentally studied. The response surface methodology (RSM) is used to analyze the three phase mass transfer coefficient under different conditions, i.e., rotation speeds (8, 10, and 12 s−1), volumetric solid content fractions (0, 6 and 12%), gas flow rates (6, 8, and 10 m3 h−1) and temperatures (40, 54, and 68 °C). With the RSM, it was found that all of these four operational parameters are significant in affecting the mass transfer coefficient, with the rotation speed being the most significant one. A new correlation is developed with a quadratic term for solid content fraction, indicating that there is a minimum value of mass transfer coefficient at a certain solid content fraction. Compared with traditional experimental design and correlation methods, the RSM in this study reduces experiment time and provides a better correlation to predict the mass transfer coefficient.

Liquid-like granular film from granular jet impact

Dynamic behaviors of dense granular jets impacting a flat target are experimentally studied and numerically simulated using the Discrete Element Method. Effects of the granular jet velocity (u0⩽6.5m/s), the particle diameter (82⩽d⩽350μm), the jet diameter (1⩽D⩽12mm), and the volumetric solid content ratio of the granular jet (0.05⩽xp<0.62) on the flow patterns are investigated. Two patterns were identified: the thin, liquid-like granular film and the diffuse pattern. The profile and thickness of granular films have been characterized. The transition critical parameters and maps of the two patterns are obtained in this work. Results show that the regimes of the granular jet impact are primarily determined by the ratio of jet diameter to particle diameter (D/d) and solid content ratio (xp). A compacted dead zone over the target forms with large D/d and xp, which subsequently causes rapid interparticle inelastic collisions and circular motion of the granular film.

On developing improved modelling and scale-up procedures for pneumatic conveying of fine powders

Pneumatic transport of fine powders in fluidized dense-phase mode is becoming increasingly popular in various industries, such as power, chemical, cement, refinery, alumina, pharmaceutical, limestone, to list a few, because of the reasons of reduced gas flow rate and power consumption, decreased conveying velocities, improved product quality control, reduced pipeline sizing and wear rate, increased workplace safety etc. For the reliable design of a pneumatic conveying system, it is important to accurately predict the total pipeline pressure drop. However, accurate prediction of pressure drop from an improved understanding of the fundamental transport mechanism of fluidized dense-phase flow condition has only made limited progress till now because of the highly concentrated and turbulent nature of the gas-solids mixture. Power plant fly ash (median particle diameter: 30μm; particle density: 2300kg/m3; loose-poured bulk density: 700kg/m3) was conveyed through different pipelines (69mm I.D.×168m long; 105mm I.D.×168m long; 69mm I.D.×554m long). 8 different fly ash samples were tested in a fluidizing column for their deaeration characteristics and fluidized bulk densities were determined. Governing equations of flow for the dense-phase pneumatic conveying system of fine powders were solved using Runge-Kutta-Fehlberg (RKF45) method for different fluidized bulk densities of fly ash and air flow rates. The results have shown that the particle and actual gas velocities and the ratio of the two velocities increase in the direction of flow, while a reverse trend was apparent for the solids volumetric concentration. The results were compared against the predictions obtained using existing empirical relations for particle velocity. To develop an improved model for solids friction factor, an existing reliable pure dilute-phase model has been modified for dense-phase flow condition by incorporating sub-models for particle to actual gas velocity and impact and solids friction factor. The developed solids friction factor model was validated by using it to predict the total pipeline pressure drops for larger and longer pipelines and by comparing the experimental and predicted pneumatic conveying characteristics. The results have shown improved reliable predictions and that the model is capable of addressing the gradual transition of flow mechanism from dense- to dilute-phase. The accuracy of prediction is similar (in fact better in certain scale-up cases) when compared to a recently developed two-layer based model (developed by some of the authors). The results demonstrate the importance of incorporating particle and actual gas velocity terms in the model of solids friction factor instead of the prevailing techniques that overly depend on using superficial gas velocities.

An instrumentation system for multi-parameter measurements of gas-solid two-phase flow based on Capacitance-Electrostatic sensor

In this paper, an instrumentation system for the measurements of local solid volumetric concentration, local solid velocity, local solid mass flowrate and solid mass flowrate in gas-solid two-phase flow system is developed. It is based on a new type of a Capacitance-Electrostatic sensor (CES). The CES sensor is mainly composed of a capacitance electrode array and two electrostatic electrode arrays. The optimum design of the sensor is achieved by finite element method. The capacitance electrode array is employed to detect the solid distribution over the cross-section of the pipe, and the local solid volumetric concentration measurement is further derived. The electrostatic electrode arrays are used to measure the local solid velocities in conjunction with cross-correlation method. From the local solid velocity and local volumetric concentration, the solid mass flowrate and the local solid mass flowrate can be achieved. The developed system for the local solid volumetric concentration measurement is verified through analogue simulation experiments and static experiments. Finally, the system is employed to measure the local solid volumetric concentration, local solid velocity, local solid mass flowrate and solid mass flowrate on a belt conveyor. The experimental results show that the measurement error of the local solid volumetric concentration measurement results are less than 10.43% for solid local volumetric concentration ranging from 0.02 to 0.56, the standard deviations of the local solid velocity measurement results are less than 0.42 for solid velocity ranging from 3.5 m/s to 15.0 m/s, and the relative error of the solid mass flowrate is within −19.6% to +14.9% for solid mass flowrate ranging from 0.006 kg/s to 0.103 kg/s, indicating that the system is capable of achieving multi-parameters measurement in gas-solid two-phase flow system.

Porous Ni/ZrO2 Cermet from Highly Concentrated Composite Colloid

Rheology and shaping of concentrated cermet suspensions consisting of nickel (Ni) and yttria‐stabilized zirconia (YSZ) nanoparticles in water have been examined over a broad range of volumetric solids concentration (ϕ = 0.1–0.4) and Ni fraction (fNi = 0.15–0.45). Preferential adsorption of pyrogallol‐poly(ethylene glycol) polymer (i.e., Gallol‐PEG) on surface of the Ni and YSZ particles imparts steric hindrance between the suspending particles so that fluidity can be obtained under shear stress. The cermet suspensions exhibit shear‐thinning flow behavior under steady‐shear measurement over shear rates of 100–103 s−1. Yield stress and yield strain of the suspensions appear to vary pronouncedly with ϕ and fNi under oscillatory shear over a shear‐strain range of 10−1–103%. With the Gallol‐PEG adsorption, an apparent viscosity less than 6 × 10−1 Pa.s at a shear rate of 102 s−1 has been obtained for the highly concentrated composite suspension with ϕ of 0.40 and fNi of 0.25. A high solids concentration effectively prohibits phase segregation during wet‐shaping processes. Uniform green compacts have been obtained from slip casting of the concentrated cermet mixture (ϕ = 0.30) without use of binder and are then fired at 1200°C under reducing atmosphere to form porous Ni/YSZ compacts. Relative sintered density increases from 65% to 75% of the theoretical value when fNi was increased from 0.15 to 0.45, due mainly to the lower sintering temperature required for the Ni phase.

Non-invasive investigation of the cross-sectional solids distribution in CFB risers by X-ray computed tomography

We apply X-ray computed tomography for non-invasive investigation of the distribution of solids over the cross-section of a pilot plant scale circulating fluidized bed riser and present a novel method to derive volumetric solids concentrations from tomographic raw data. In this, the elimination of low-energetic radiation from the incident X-ray spectrum plays an essential role to avoid detrimental beam hardening effects, which are caused by the pipe material and the fluidized solids. The presented technique is applied for quantitative analysis of the radial solids concentration distribution in a gas-solid circulating fluidized bed riser. The examined operating range covers mean solids concentrations between 2.7vol% and 37.2vol% whilst the superficial gas velocity is varied between 1.5ms−1 and 6.0ms−1. The high spatial resolution of the measured data permits evaluation of the influence of the overall solids holdup and the superficial gas velocity on the radial solids concentration profile. Comparison of the cross-section averaged solids concentrations obtained by X-ray computed tomography with those inferred from differential pressure measurements confirms the high accuracy of the applied method. Based on a comprehensive set of measurement data a model is developed that allows for the prediction of the radial solids concentration distribution in vertical gas-solid upflow.

Determination of volumetric concentration of solids in vertical pipeline hydrotransport

This paper presents an application of radioisotopes with reference to the determination of the solid phase volumetric concentration in a hydromixture by calibration of the measuring set. It shows how the gamma absorption equipment consisting of radioactive isotopes 241 Am and scintillation probe, may be applied to the measurement of solid particles volumetric concentration in a flow. It is based on fact that the intensity of a gamma beam decreases as it passes through matter. In the described experiments as solid phase the ceramic models representing natural polymetallic ocean nodules were used. The especially constructed calibration stand and obtained relation between the related intensity of radiation and mean volumetric concentration of the solid phase are presented.

Comparison of measurement methods of the front velocity of small-scale debris flows

Debris flow is a gravity-driven process, which is characterized by a travelling dense surge including large boulders, and it is followed by a more fluid tail. These characteristics make difficult the measurement of the mean flow velocity by means of common hydraulic techniques. Different methods can be used at real scale and small-scale to measure the front velocity but a dedicate comparison between available methods is still lacking. This research aims to compare the front velocity measurements in the transport zone of a miniature debris flow using three devices: i) a common digital video camera (29 frames per second); ii) a high speed thermo camera (60 fps); and iii) a laser photoelectric sensors system. The statistical analysis of data has highlighted no significant differences exist between front velocities obtained by means of the video camera and the thermo camera, whereas photocells data statistically differ from those achieved via the other systems. Some lack of data recorded by photocell was documented, while the thermo camera technique did not show significant loss of information being also helpful to detect the kinematic behaviour of single particles. Finally, the tests confirmed the influence of the solid volumetric concentration in the debris-flow mechanics, which promotes, &lt;em&gt;ceteris&lt;/em&gt; &lt;em&gt;paribus&lt;/em&gt;, the debris-flow slowing down.

Residual moisture content and separation efficiency optimization in pilot-scale vibrating screen

Vibrating screening is still one of the main operations considering solid–solid and solid–liquid separation processes. Although it is an equipment of simple design and execution, the full description of a screening unit operation may be difficult to predict, considering that several operational variables can influence it. Therefore, the main objective of this work was to evaluate the best possible combination between the process variables screen aperture size, the volumetric concentration of solids in the feed, and the g-force (measurement of the vibration). This configuration predetermined values for moisture content of the retained material over the screen and separation efficiency regarding particle size. For this, a suspension of phosphate rock concentrate (with a particle density of 3.25g/cm3 and average particle size of 95μm) was diluted in water to perform the experiments in a pilot-scale vibrating screen. The results were analyzed statistically and correlations for each response were fit. The highest values of separation efficiency were found with the lowest values of cut-size diameter, which is desirable in terms of separation. A multi-objective optimization in the experimental range was developed, finding the optimal point for the moisture content of 17.29% and the separation efficiency of 86.88%. The effects of screen aperture size and g-force had important roles in this study.