Disengagement Time Research Articles

Iron status in early infancy is associated with trajectories of cognitive development up to pre-school age in rural Gambia.

Iron deficiency is among the leading risk factors for poor cognitive development. However, interventions targeting iron deficiency have had mixed results on cognitive outcomes. This may be due to previous interventions focusing on the correction of iron deficiency anaemia in late infancy and early childhood, at which point long lasting neural impacts may already be established. We hypothesise that the relationship between iron status and cognitive development will be observable in the first months of life and will not be recovered by 5 years of age. Using data from the Brain Imaging for Global Health (BRIGHT) Study in Gambia (n = 179), we conducted mixed effects modelling to assess the relationship between iron status at 5 months of age and trajectories of cognitive development from 5 months- 5 years using (i) a standardised measure of cognitive development (Mullen Scales of Early Learning) and (ii) an eye-tracking assessment of attention processing (visual disengagement time). All infants were iron sufficient at 1 month of age. At 5 and 12 months of age 30% and 55% of infants were iron deficient respectively. In fully adjusted analyses, infants in the lowest tercile of soluble transferrin receptor (sTfR) (best iron status) achieved MSEL Cognitive Scores on average 1.9 points higher than infants in the highest sTfR tercile (p = 0.009, effect size = 0.48). There was no evidence that this group difference was recovered by 5 years of age. Infants in the lowest sTfR tercile had visual disengagement time 57ms faster than the highest tercile (p = 0.001, effect size = 0.59). However, this difference diminished by early childhood (p = 0.024). Infants are at risk of iron deficiency in early infancy. A relationship between iron status and cognitive development is apparent from 5 months of age and remains observable at 5 years of age. One mechanism by which iron availability in early infancy impacts brain development may be through effects on early attentional processing, which is rapidly developing and has substantial nutritional requirements during this period. To support neurocognitive development, prevention of iron deficiency in pre- and early postnatal life may be more effective than correcting iron deficiency once already established.

Shear Banding in Entangled Polymers: Stress Plateau, Banding Location, and Lever Rule.

Using molecular dynamics simulation, we study shear banding of entangled polymer melts under a steady shear. The steady shear stress vs shear rate curve exhibits a plateau spanning nearly two decades of shear rates in which shear banding is observed, and the steady shear stress remains unchanged after switching the shear rates halfway in the range of shear rates within the plateau region. In addition, we find strong correlation in the location of the shear bands between different shear rates starting from the same microstate configurations at equilibrium, which suggests the importance of the inherent structural heterogeneity in the entangled polymer network for shear banding. Furthermore, for the steady shear bands persisting to the longest simulated time of 9.0τd0 (disengagement time), the shear rate in the slow band and the relative proportion of the bands do not change very much with the increase of imposed shear rate, but the shear rate in the fast band increases approximately in proportion to the imposed shear rates, in contradiction to the lever rule.

Modelling of Elongational Flow of HDPE Melts by Hierarchical Multi-Mode Molecular Stress Function Model.

The transient elongational data set obtained by filament-stretching rheometry of four commercial high-density polyethylene (HDPE) melts with different molecular characteristics was reported by Morelly and Alvarez [Rheologica Acta 59, 797–807 (2020)]. We use the Hierarchical Multi-mode Molecular Stress Function (HMMSF) model of Narimissa and Wagner [Rheol. Acta 54, 779–791 (2015), and J. Rheology 60, 625–636 (2016)] for linear and long-chain branched (LCB) polymer melts to analyze the extensional rheological behavior of the four HDPEs with different polydispersity and long-chain branching content. Model predictions based solely on the linear-viscoelastic spectrum and a single nonlinear parameter, the dilution modulus for extensional flows reveals good agreement with elongational stress growth data. The relationship of dilution modulus to molecular characteristics (e.g., polydispersity index (PDI), long-chain branching index (LCBI), disengagement time ) of the high-density polyethylene melts are presented in this paper. A new measure of the maximum strain hardening factor (MSHF) is proposed, which allows separation of the effects of orientation and chain stretching.

Are novice drivers competent to take over control from level 3 automated vehicles? A comparative study with experienced drivers

With level 3 automated vehicles poised to appear on the roads soon, takeover remains a major challenge. At present, the effect of manual driving experience on takeover performance is unknown. Therefore, a simulator study was conducted to investigate the influence of driving experience (novice and experienced) on takeover performance in different takeover time budgets (7 s and 5 s) and in combination with a visual secondary task (i.e., surrogate reference task). Data from 48 young and middle-aged participants consisting of 24 novice and 24 experienced drivers were used for this study. Researchers found that the overall stability of evasive maneuvers by novice drivers was considerably worse than that by experienced drivers. A detailed analysis showed that the influence of driving experience on takeover stability was mainly reflected in longitudinal control rather than lateral control. A significant interaction between driving experience and visual secondary task showed that the latter had a substantial impact on the takeover stability of experienced drivers but not on that of novice drivers. Researchers also found that rich manual driving experience cannot make the takeover process of experienced drivers more stable than that of novice drivers under conditions of eye-off-road. In addition, no significant difference was found between novice and experienced drivers in automation disengagement time, takeover time and minimum time to collision. Results indicate that novice drivers have poor takeover stability and weak adaptability, but their longitudinal collision risk is not deteriorated by the lack of manual driving experience.

Iron Status in Early Infancy Is Associated With Attentional Flexibility and Cognitive Achievement in Rural Gambia

ObjectivesTo determine the relationship between iron status in early infancy (1–5 months) and longitudinal trajectories of cognitive development (5–18 months) in a cohort of infants from rural Gambia. MethodsThis study used data from the Brain Imaging for Global Health (BRIGHT) study, which recruited pregnant women (n = 223) and followed up mothers and their children to 18 months of age (n = 191). Infant blood samples collected at 1 and 5 months of age were analysed for soluble transferrin receptor (sTfR) and ferritin using a COBAS INTEGRA 400 (Roche). Cognitive development was measured at 5, 8, 12 and 18 months of age using the Mullen Scales of Early Learning (MSEL) and an eye tracking measure of attentional flexibility (disengagement time). For each outcome measure, mixed effects models of individual developmental trajectories from 5–18 months of age were developed. Each model had a different measure of iron status as the primary exposure (ferritin or sTfR at 1 or 5 months of age) and was adjusted for confounding factors. ResultsPrevalence of iron deficiency (ferritin < 12μg/L or < 30 μg/L if CRP > 5mg/L) increased from 0% to 29.5% between 1 and 5 months of age. In mixed effects models, a -1mg/L difference in sTfR (indicating better iron status) at 1 month of age was associated as with a 31.2ms difference in disengagement time (SE = 13.1, p = 0.017) at each time point from 5–18 months of age, but was not associated with MSEL developmental trajectory. A -1mg/L difference in sTfR at 5 months of age associated with a 0.6 point difference in MSEL score from 5–18 months of age (SE = 0.180, p = 0.001) and a 10.6ms difference in disengagement time (SE = 4.8, p = 0.028) across the same period. There was no relationship between ferritin concentration at 1 or 5 months and trajectories of either MSEL or disengagement time (all p > 0.05). ConclusionsInfants under 6 months of age in rural Gambia are at risk of iron deficiency. Poor iron status in early infancy, measured by sTfR but not ferritin, is associated with both global cognition and a specific measure of attentional flexibility, from 5–18 months of age. Maintenance of adequate iron in infants up to 6 months of age may benefit the developing brain. Funding SourcesBill and Melinda Gates Foundation and Medical Research Council (UK).

Hydrolytic degradation of tri-iso-amyl phosphate-dodecane system

A solution of 1.1 M tri-iso-amyl phosphate (TiAP) in n-dodecane (n-DD) has been proposed as a candidate solvent for reprocessing of spent nuclear fuel arising from fast reactors. Significant amounts of radioruthenium are produced as a fission product in fast reactors. To minimize the extraction of radioruthenium during the separation of uranium and plutonium, it was proposed to carry out the solvent extraction process at nitric acid concentration ranging from 4 to 5 M. Under these process conditions, it is quite likely that the solvent phase can undergo hydrolytic degradation, which can cause significant changes in the physicochemical properties of the solvent phase and hamper the recovery of uranium and plutonium. In view of this, the hydrolytic degradation of 1.1 M TiAP/n-DD was studied as a function of nitric acid concentration, duration of degradation and process temperature. The physicochemical properties of the hydrolytically degraded organic phase such as density, viscosity, interfacial tension, phase disengagement time was studied and compared with those obtained for thermally degraded solvent (in the absence of nitric acid) and neat solvent phase. The degree of damage was assessed by the uranium retention test in the hydrolytically degraded solvent phase and the procedure for the removal of degradation products from the organic phase was reported. The results revealed that hydrolytic degradation resulted in the formation of acidic degradation products of both TiAP and n-DD. While most of the acidic degradation products arising from TiAP appears to be washable by sodium carbonate during clean-up, a small amount of hydrocarbon degradation products, e.g. nitrolic acid, sparingly soluble in sodium carbonate seems to retain uranium in organic phase during recovery. The formation of nitration degradation products was confirmed by FT-IR spectroscopy. The recovery of uranium was more that 95% after the clean-up of degraded solvent.

Modeling and Analysis of Gear Shifting Process of Non-Synchronizer AMT Based on Collision Model

In the gear shifting process of a clutchless automated mechanical transmission (AMT), the potential collision between sleeve and dog gear may increase both vehicle jerk and gear changing duration. Therefore, the gear shifting process’s mechanism analysis and dynamic modeling are the essential prerequisites to improve gear shifting quality. This paper analyzes the potential collision between the sleeve and the dog gear which both with concave-convex profiles, the tooth-side chamfer considered. To model the collision process, a fast-determining collision face method based on an intersection map is proposed, and the Monte Carlo method and equivalent depth are employed to calculate the collision stiffness. Then, the stiffness-damping model of the collision process and an 8-degree-of-freedom dynamic model of the gear-shifting system are established. Finally, taking a two-speed clutchless and non-synchronizer automated mechanical transmission (NSAMT) as an example, the established dynamic model of the gear-shifting system is applied, and simulation verification is performed in Matlab/Simulink. The simulation results show that the established model can accurately reflect the changes of forces, speeds, and displacements of sleeve and dog gears during the collision and effectively reflect processes of the disengagement of the sleeve, the speed changes in active synchronization, the engagement of sleeve and gear keeping. Besides, the results also show that the tooth-side chamfer will increase the disengagement time, while it is conducive to gear keeping, and that unloading the drive motor can decrease the disengagement time due to the existence of the tooth-side chamfer.

Selection criteria of diluents of tri-n-butyl phosphate for recovering neodymium(III) from nitrate solutions

The selection of a proper diluent should be based on several criteria such as the distribution ratio, phase disengagement time, cost, safety and environmental impact of the process. The effect of different diluents on the solvent extraction of Nd(III) by the neutral extractant tri-n-butylphosphate (TBP) from nitrate feed solutions was studied. The nature of the diluent had little effect on the extraction kinetics of Nd(III) by TBP above 2.5min. In general, phase disengagement times were relatively shorter for aromatic diluents compared to aliphatic diluents. Conversely, extraction efficiencies were the highest for aliphatic diluents, slightly lower for mixed aliphatic-aromatic diluents and much lower for aromatic diluents. The poorer extraction efficiencies of aromatic diluents maybe due to the lower concentration of free extractant as a result of the stronger interactions of the diluent with water and/or of the diluent with the extractant. Under the experimental conditions, the differences in extraction between aliphatic and aromatic diluents decreased with increasing the salting-out effect of nitrate ions in the feed. At nitrate concentrations of 4.5molL−1 or more, the different diluents had a limited influence on the metal extraction with 1molL−1 TBP from feed solutions of 1gL−1 Nd(III). Thus, under these conditions, the selection of the diluent can be preferably based on its cost, safety and biodegradability rather than on its physico-chemical properties.

Limitations of Reptation Theory for Modeling the Stress‐Dependent Rheological Behavior of Polyethylene Terephthalate Above the Glass‐Transition Temperature

The biaxial stretch blow molding is an established process for manufacturing plastic containers, in which preforms are stretched both in circumferential and axial directions while being blown into a mold. In the development phase of these products, computer‐aided analysis tools are extensively used to increase the material and process efficiency. The accuracy of these tools depends on the underlying material models and parameters. The aim of this article is to investigate the suitability of reptation theory for the prediction of the strain‐dependent rheological behavior of polyethylene terephthalate (PET) in the stretch blow molding process. Reptation theory has already been successfully applied to a number of polymer melts in the past decades. However, the practical applicability of reptation theory for predicting the strain‐dependent rheological behavior of highly viscous polymers slightly above the glass‐transition temperature, as is the case with stretch blow molding, has not yet been fully investigated. In the first step, the constitutive material model equation of reptation theory is implemented and the necessary model parameters are determined using various measurement methods. However, the measurements could not be conducted with the same accuracy as in the case of polymer melts, because the measurement methods used showed instabilities in the glass‐transition temperature range, which led to high measurement uncertainties. Consequently, the application of the material model does not match quantitatively to biaxial stretch tests. Qualitatively, on the other hand, the material model successfully reproduces the stress–strain behavior of PET films at low strains. In case of temperature dependence, the model results are neither qualitatively nor quantitatively satisfactory. The temperature dependency of the material model has been further investigated in the second step. It was shown that the derivative of the Doi–Edwards memory function with respect to the temperature has an inflection point if the stretching duration is equal to the disengagement time. For very small disengagement times compared to the stretching duration, the results of the model match the experimental observations. For high disengagement times induced by the large viscosities near the glass‐transition temperature and for low stretching times induced by high strain rates; however, the Doi–Edwards memory function cannot predict the experimental observations correctly. The investigations show that reptation model qualitatively predicts the strain behavior of biaxial stretched PET films at low strains correctly. However, different measurement approaches for a more accurate and reproducible determination of the material properties and a modification of the model are required in order to adapt the model to highly viscous melts above the glass‐transition temperature. The results have shown that the process conditions of the two‐stage stretch blow molding, such as high strain rates and low processing temperatures, exceed the validity limits of reptation theory. POLYM. ENG. SCI., 60:765–772, 2020. © 2020 The Authors. Polymer Engineering &amp; Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.

Physiochemical Properties of Gamma-Irradiated Tri-iso-amyl Phosphate–Dodecane System: Effect of Aqueous Phase Acidity

ABSTRACTTri-iso-amyl phosphate (TiAP) in dodecane (DD) is emerging as a potent alternative for the extraction of suitable actinides from nitric acid solutions comprising various metal ions. A detailed investigation on the evolution in physicochemical properties upon gamma irradiation of TiAP-DD system has been carried out. Physical properties, such as density, viscosity, phase disengagement time, interfacial tension, etc., were measured for neat as well as irradiated solvent phases. Effect of aqueous phase acidity, which is an important parameter during extraction, on the hydrodynamic properties of the solvent during radiolysis was compared. ATR–FTIR spectroscopy of the irradiated phase was compared to find out the formation of new classes of compounds, if any.

Application of a Sustainable Bioderived Solvent (Biodiesel) for Phenol Extraction.

Replacement of volatile organic compound solvents by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns. In the present work, a bioderived solvent, soybean oil methyl ester, which is better known as biodiesel and is a nonvolatile organic compound, was used as a solvent to replace the fossil solvent (kerosene) for phenol extraction. First, biodiesel was selected as an optional solvent to replace kerosene based on Hansen solubility parameter calculation results. Second, the effects of solvent concentration, equilibrium pH of the aqueous phase, temperature, extraction time, etc. on phenol extraction were examined. The results show that biodiesel has strong extraction ability on phenol extraction than that of kerosene. An acidic environment decreases the phase disengagement time. Phenol extraction reached equilibrium in 30 s of contact time at room temperature. McCabe–Thiele diagram calculation results show that the phenol extraction efficiency can reach 98% in three theoretical stages at an A/O ratio of 10:1 (Cyanex923 + biodiesel). Finally, the extraction mechanism indicated that biodiesel could reduce the intermolecular hydrogen bond forces in the extractant so as to improve the extraction efficiency.

Dynamics of Supramolecular Self-Healing Recovery in Extension

Self-healing materials are prized for their ability to recover mechanical properties after damage. Supramolecular polymer networks have been demonstrated to have the ability to recover without the need for extraneous material components or the use of external stimuli. Surprisingly, there is little quantitative measure of self-healing dynamics and recovery. In this work, we develop a tool using a filament stretching rheometer to probe self-healing dynamics in creep and constant rate of extension. We experimentally determine the effect of process time scales, τH and τW, on the degree of recovery for two distinct supramolecular architectures. These results are put into the context of molecular time scales such as disengagement time, the Rouse time, and bond lifetime. We find that entangled polymers undergo sequential healing, whereby at short times, dynamics are dominated by entanglement recovery followed by recovery of associations. For an unentangled polymer, recovery is seemingly dominated by association ...

Comparative Study of Simultaneous Removal Performance of Silica and Solid Colloidal Particles from Chalcopyrite Bioleachate Solution by Washing and Coagulation Methods

Most of the surface reserves of copper minerals are oxidized while underground mining leads to rich silica–chalcopyrite–pyrite ore. Based on the challenges of the twenty-first century, the (bio)-hydrometallurgy processing is suggested as an alternative route to replace conventional techniques. However, the search for a sustainable metallurgy and/or more effective method to decrease impurities for efficient solvent extraction led to a comparative study of the removal performances of silica and solid colloidal particles from bioleachate solution by comparing the techniques using Shellsol set #2325 and Magnafloc set #1597, respectively. Three ratios (thinner/aqueous) or/and (coagulant /aqueous) of 1/2, 1, and 3/2 were assessed, along with the disengagement time and the required absorbed dose of Magnafloc 1597. The search for the alternative route also sought to ensure that the requirements in terms of concentration values at solvent extraction stage did not exceed 500 and 75 ppm, respectively. Findings show that the diluent/wash method is less efficient in terms of the removal performances of silica and solid colloidal particles from the bioleachate solution, but the phase disengagement time was similar, being comparatively around 150 s. The results of Magnafloc 1597 coagulation tests show removal performances of silica and colloidal particles from the bioleachate solution to be greater than 300 ppm, with a volume ratio of 1/1 for recovery rates of 68 and 58%, respectively, for SiO2 and colloidal solids in suspension. In comparison, the employment of Shellsol 2325 achieved silica removal efficiencies of 20.92 and 40%, respectively, of SiO2 and colloidal fine particles in suspension. A decreased phase separation time in aqueous continuity from 245 to 148 s has been recorded with a ratio of 1/1 (thinner or coagulant/aqueous). On the other hand, coagulant concentration of 300 ppm was retained. Hence, it could be assumed that the coagulation showed better results than the washing method.

Tool wear modeling in rotary turning modified by ultrasonic vibration

Modification of conventional turning operation is carried out by using different methods to improve machinability conditions. In this study, rotary turning is modified by adding ultrasonic vibrations to cutting tool. Accordingly, the effect of this method on output parameters namely, tool wear and temperature, cutting force, and surface roughness, is investigated. Having detailed analysis, finite element method is used beside the experiments. As a result, it was revealed that tool-chip engagement time during rotary motion of cutting tool significantly reduced wear propagation on tool faces. This was explained by heat analysis in which disengagement time resulted in lower heat transfer from chip to tool. Moreover, the result of surface roughness produced in vibratory-rotary turning was compared by rotary one.

The optimal use of tris-2-ethylhexylamine to recover hydrochloric acid and metals from leach solutions and comparison with other extractants

This paper describes the use of TEHA for HCl recovery from a leach solution generated by a hydrometallurgical plant. Four organic extractants were tested including TEHA, Alamine 336, Cyanex 923 and TBP. TEHA organic system performed best in terms of acid extraction, stripping and scrubbing efficiency. The successive extraction shows that more than 99% HCl was extracted after three stages of extraction. Scrubbing tests with different A/O ratios at different temperatures were conducted to identify the optimal conditions to separate HCl, Mn and Fe. After scrubbing the loaded organic solution at an A/O ratio of 1:4 and 22 °C, 94–100% of entrained metals were removed in a single contact with only 5.2% acid lost in the loaded scrub liquor. It was found that the phase disengagement time was in the range of 2–4 min for both extraction and stripping, indicating reasonable fast phase separation. Based on these results from batch tests, it can be expected that after optimisation in a counter current circuit consisting of extraction, scrubbing, selective and bulk stripping, nearly all metals and HCl would be recovered and recycled.

Phase equilibrium and protein partitioning in aqueous two-phase systems containing imidazolium ionic liquids and surfactant at low voltage levels

In this paper, the binodal data of aqueous two-phase system (ATPS) containing imidazolium-based ionic liquids (chlorinated 1-ethyl-3-methylimidazole, [Emim]Cl), and a non-ionic surfactant (octylphenol polyethoxylene, Triton X-100) was obtained by means of the cloud point method in the temperature intervals T=(288.15–308.15) K. It was found that the [Emim]Cl/Triton X-100 ATPS was sensitive to temperature and had a long phase segregation time. Screening experiments of various additives showed that adding 7% of sodium dodecyl sulfate (SDS) to the total mass of surfactants (w/w) reduced the temperature sensitivity, and improved the phase separation rate of the system. The liquid-liquid equilibrium (LLE) data of [Emim]Cl/Triton X-100 ATPS without additive and containing 7% SDS at 298.15K was further studied according to the cloud point method. To further shorten the long phase disengagement time, a low-voltage alternating current (AC) electric field was added to the [Emim]Cl/surfactant ATPS. Through the optimization of AC electric field conditions (such as electric field type, frequency and duty ratio), a relatively fast and stable [Emim]Cl/surfactant ATPS was established. In 0.67V/cm field strength, 1000Hz frequency and 50% duty ratio of impulse waveform, the phase splitting time is shortened by 2–3 times. With and without electric field, protein partitioning of cytochrome c (Cyt-c), bovine serum albumin (BSA) and lysozyme (Lys) in [Emim]Cl/surfactant ATPS indicated that Cyt-c and BSA tended to distribute in the bottom phase, while Lys was inclined to distribute in the top phase. The application of the AC electric field can still decrease the phase separation time in the protein distribution process, and has no significant effect on the distribution behavior of proteins. Furthermore, Lys activity in the top phase of ATPS was significantly enhanced, which could be caused by the low concentration of Triton X-100 in the top phase based on the comparison of Lys fluorescence spectra analysis in aqueous solution, in the top phase and in the bottom phase of [Emim]Cl/surfactant ATPS.

Physicochemical properties of PUREX solvent on hydrolytic and chemical treatment

Physicochemical properties such as density, viscosity, interfacial tension, and phase disengagement time were measured after subjecting tri-butyl phosphate based solvent systems to hydrolytic and chemical treatment at 40 and 60 °C for significant time. Variations in viscosity, phase separation time and interfacial tension were significant compared to fresh solvent, suggesting the fluid-dynamics of the system may be altered at high temperature of 60 °C. The marginal variation in the interfacial tension values even after accelerated treatment at 40 °C and the FT-IR spectral analysis of treated solvent, revealed the solvent to exhibited good hydrolytic and chemical stability at 40 °C.

Physicochemical and radiolytic degradation properties of dihexyloctanmide-imidazolium ionic liquid

N,N-dihexyloctanmide (DHOA) in ionic liquid medium has been proposed for the solvent extraction of actinides from nitric acid solutions. This paper reports the physicochemical and hydrodynamic properties of the solvent system containing N,N-dihexyloctanmide (DHOA) in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) ionic liquid, for the first time. The properties such as density, viscosity, phase disengagement time etc. were measured for irradiated and unirradiated liquids composed of DHOA, [C4mim][NTf2] and 1.1M solution of DHOA in [C4mim][NTf2]. The results were compared with the values obtained for the nitric acid equilibrated–organic phases. ATR-FTIR spectroscopy and dynamic light scattering (DLS) measurement of the ionic liquid phase was employed for characterizing interaction between the ionic liquid-DHOA-nitric acid, and the aggregate size of the adduct formed in the solution.

Evolution in the physiochemical properties of alternate PUREX solvent on hydrolytic and chemical treatment

ABSTRACTPhysiochemical properties such as density, viscosity, interfacial tension (IFT) and phase disengagement time (PDT) were measured after subjecting tri-iso-amyl phosphate (TiAP)-based solvent systems to hydrolytic treatment at 40 and 50°C, for 400 h. The change in viscosity between the degraded and fresh solvent was significant compared with the change in density, which could be due to the formation of intermediate compounds susceptible to hydrogen bonding. The marginal variation in the IFT values even after accelerated treatment and the absence of any new class of compounds after treatment, as evidenced by FTIR spectral analysis, revealed that the solvent exhibited good thermal and chemical stability.

Clarification and solvent extraction studies of a high talc containing copper aqueous solution

Effects of different flocculants on the clarification of a copper aqueous solution destined for solvent extraction were investigated. The test work was conducted on the pregnant leaching solution (PLS) of a high talc containing copper ore that had a high propensity of bearing a large amount of suspended solids. The clarification test work was conducted using three commercial high molecular anionic polyacrylamide polymer flocculants: rheomax® DR 1050, brontë 103, and senfloc® 2660. Solvent extraction tests were done using 30% (v/v) LIX 984N at pH 1.8. The parameters of clarification and solvent extraction were the flocculant dosage (0, 58.14, 116.28, 232.56 and 348.84g/t) and the ratio O/A (1/5, 1/2, 2/3, 1/1, 3/2, 2/1, and 5/1), respectively. The analysis results of the PLS showed it contained 2000ppm of solids in suspension. The optimal conditions for clarification and solvent extraction were a dosage of 116.28g/t and an O/A of 1.5, respectively. Under optimal conditions, the residual total suspended solids (TSS) in the clarified solutions were 1196ppm, 954ppm, and 928ppm; the phases disengagement time (PDT) for organic continuous dispersion were 70s, 80s and 60s; the percent TSS entrained in the organic phase were 26.76%, 28.93% and 25.32%; copper recoveries were 97.63%, 98.98% and 95.13%, with rheomax® DR 1050, brontë 103 and senfloc® 2660, respectively.