Column Extractor Research Articles

Experimental study of the flow structure in packed tray-type column extractors

Liquid extraction is a well-known separation process that has been widely used in the chemical industry for many years, for example, in the selective purification of oil fractions, in the purification of liquefied gases from hydrogen sulfide, in the production of petrochemicals, in the recovery of metals, in nuclear fusion, in food and pharmaceutical industry. On-going elaborations aimed at engineering solution search in order to improve mass-transfer processes are in progress on a permanent basis. Combination of trays and packing in the fractionator results in stream disequilibrium which leads to worse hydrodynamic conditions in the splitter (extraction, rectifier tower and etc.) and causes significant difficulties in stable operating process maintaining. The study objective is to review the structure of stream structures in the extraction tower via examples of trays and packing combinations since the mentioned contact devices are widely used in industry but they are conventionally applied as individual contact devices and not in combination. Combination of the above contact devices may earn a supplementary synergetic effect. In the course of the experiment it was found out and described in graphic format that stream disequilibrium could be eliminated and hydrodynamic conditions in the extraction tower could be improved via extra stream supply in the tower shell. Research will be useful for the development of new designs of column equipment, for example, extraction. In order to expand the experiment in various hydrodynamic modes, it is proposed to simulate the experiment using, for example, the Solid Works 2020 software package and, in particular, one of its add-ons - Flow Simulation.

Extraction kinetics of target components from mineral raw materials in column devices

Methods for predicting the kinetics of extraction of the target component from mineral raw materials for direct-flow and counter-current column extractors have been proposed. To analyze the operation of various industrial devices, the extraction processes of which are carried out in the layer, technique based on specific productivity has been proposed. The kinetic regularities of Al2O3 extraction from bauxite specs and sulfur from sulfur ore have been studied as well as the data of current countercurrent extractors from the field of hydrometallurgical plants of Ukraine have been used.

Hydrodynamics of pulsed sieve-plate extraction columns

This paper presents a review of some hydrodynamic parameters in pulsed sieve-plate extraction columns. The hydrodynamic parameters in liquid-liquid systems in these columns were analyzed regarding the effects of operating and geometrical parameters. The values of Sauter mean drop diameter were function of the existing work flow regimes in the column device defined as mixer-settler, emulsion and dispersion regimes. It was concluded that the dispersed-phase holdup was a function of the mean drop diameter and dispersed-phase superficial velocity. An increase in the dispersed-phase holdup induced an increase in the interface area in the liquid-liquid system. Knowledge of the value of the dispersed-phase holdup can be used for calculation of the volumetric mass transfer coefficient, one of the important factor in the design of the column extractor. It was concluded that the increase in the dispersed-phase superficial velocity is causing a decrease in axial dispersion. On the other hand, an increase in the continuous-phase superficial velocity is causing the increase in the axial dispersion coefficient. Some of the empirical equations proposed in literature for calculations of the hydrodynamic parameters were presented. These correlations, derived for determination of the hydrodynamic parameters in pulsed sieve-plate extraction columns, can be used for the design of these liquid-liquid extraction columns.

Enhanced separation of praseodymium and neodymium by kinetic “push and pull” system of [A336][NO3]-DTPA in a column extractor

A new approach was suggested in present work for improving the separation between Pr(III) and Nd(III) by a so-called kinetic “push and pull” system consisting of [A336][NO3] and DTPA in a column extractor. It is revealed that, when organic extractant [A336][NO3] is continuously pumped into the column extractor in the form of dispersed oil droplets and at the same time DTPA was injected into the aqueous feed solution when the extraction was just started, the separation factor of Pr(III) to Nd(III), βPr/Nd, increased obviously with the time, and could even achieve 21.7. Such an amazing increase in βPr/Nd value might be due to the extraction rate of Pr(III) by [A336][NO3] oil droplets being faster than that of Nd(III), while the complexing rate of Nd(III) with DTPA in the aqueous solutions being faster than that of Pr(III). The opposite order of the two rates for Pr(III) and Nd(III) result in their kinetic “push and pull” separation. In contrast, the βPr/Nd value in traditional thermodynamic separation reported in previous literatures is only around 5 or even less, even though using the same extractant [A336][NO3] and DTPA but by previously adding DTPA into the aqueous feed solutions for pre-complexing of Pr(III) and Nd(III). Various effects from the pH and addition amount of DTPA aqueous solutions, LiNO3 concentrations in initial aqueous feed solutions, the initial concentration ratios of Pr(III) to Nd(III) ions, the initial pH of aqueous feed solutions, and the concentrations of [A336][NO3] in organic phases, on the kinetic separation of Pr(III) and Nd(III) are discussed. The present work highlights a promising approach for separation of rare earths or other targets with extreme similarity in physicochemical properties.

Optimization of Atropine Extraction Process from Atropa Belladonna by Modified Bubble Column Extractor with Ultrasonic Bath

Modified Bubble Column Extraction with Ultrasonic Bath (BCE-UB) method was used to extract atropine from the stem and leaves of Atropa belladonna. Optimum condition were obtained with Kamada solvent which was chloroform-methanol-ammonia 15:15:1(v/v/v) as extraction solvent, the particle size of less than 350 µm, an extraction time of 23.95 min, a liquor to material ratio of 15.08 mL/g and an air flow of 6.31 mL/min.g. In this state, percent of extracted atropine was calculated which was equal to 6.81%. Percent of extracted atropine was 6.31% that showed a little difference compared to the predicted value. In order to study the effect of bubbles on the extraction rate, the same extraction with the previous method was performed in a stirred tank. Percent of atropine was 5.59%.

Using maximum entropy, Gamma, Inverse Gaussian and Weibull approach for prediction of drop size distribution in a liquid–liquid extraction column

In this study, drop size distribution and Sauter mean drop diameters were measured and correlated under operating variables and physical properties of the systems using a 113mm diameter Kühni column. Three systems including toluene-water, n-butyl acetate-water and n-butanol-water were experimented in this column. The countercurrent flow pattern of the liquid phases was characterized regarding the Sauter mean drop diameter and drop size distribution; a photographic method was used to assess drop sizes. The following operating variables were studied: rotor speed, flow rate of both liquid phases and interfacial tension. The drop size distribution and Sauter mean drop diameter were found to depend largely on the rotor speed and interfacial tension, albeit, only partially dependent on the phase velocities. The maximum entropy principle and the conventional probability distribution functions (Gamma, Inverse Gaussian, Weibull) have already been applied to estimate the drop size distribution. Experimental results show that the maximum entropy function describes the drop size distribution better than the conventional probability distribution functions for three systems in a Kühni column extractor. An empirical correlation is proposed for the estimation of the Sauter mean drop diameter. The acquired information would be useful in design of liquid–liquid extraction columns.

Experimental mass transfer coefficients in a pilot plant multistage column extractor

The volumetric overall mass transfer coefficients in a multistage column have been measured using axial dispersion model for toluene–acetone–water system. The effect of operating parameters on the volumetric overall mass transfer coefficients has been investigated for both mass transfer directions. The results show that the mass transfer performance is strongly dependent on rotor speed and mass transfer direction, although only slightly dependent on phase flow rates. In addition, empirical correlations to predict the overall mass transfer coefficients have been developed. The proposed correlations based on dimensionless numbers can be considered as a useful tool for the possible scale up of the multistage column extractor.

Experimental investigation of dispersed phase holdup and flooding characteristics in a multistage column extractor

In this research work, liquid–liquid extraction via three different systems has been investigated for determination of holdup, flooding velocities and holdup at the flooding points in a multistage column extractor. The effects of various parameters including rotor speed and dispersed and continuous phase velocities were studied. The results showed that the enhancement of rotor speed and dispersed and continuous phase velocities would enhance the dispersed phased holdup. There was a significant increase in the holdup at the flooding points with an increase in the rotor speed because of the smaller drops formation. New correlations were also developed for prediction of the flooding velocities, holdup at flooding points and dispersed phase holdup in the multistage column extractor. The results of the proposed correlation were compared with the experimental data obtained from the literature and the present investigation. Findings of this study demonstrated that the proposed correlations give accurate predictions for flooding characteristics.

Mass transfer performance in an Oldshue–Rushton column extractor

The volumetric overall mass transfer coefficients of an Oldshue–Rushton column have been measured using an axial diffusion model, applying two different liquid–liquid systems. The effects of the operating parameters such as rotor speed and dispersed and continuous phase velocities on the volumetric overall mass transfer coefficients have been investigated. The rotor speed was found to have a more profound effect on the column performance. The phase flow rates had little influence on the mass transfer performance. The previous models for estimation of the overall mass transfer coefficient were reviewed and their predictions were compared with the experimental data. All of the previous models failed to properly predict the experimental results under the operating conditions. Therefore, an empirical correlation was proposed for enhancement factor as a function of Re number, Eö number and dispersed phase holdup. This correlation relatively accurately predicted the mass transfer coefficients, so it could be applied to design the Oldshue–Rushton columns.

Using maximum entropy approach for prediction of drop size distribution in a pilot plant multi-impeller extraction contactor

In this study, the maximum entropy principle is used to predict the drop size distributions in a multi-impeller column extractor.

폐촉매(廢觸媒) 염산침출액(鹽酸浸出液)에서 컬럼형 추출기(抽出器)에 의한 백금(白金) 회수(回收)

Abstract In order to recover Pt from the hydrochloric acid leaching solution of spent catalysts, bench scale Karr reciprocating columnwas employed. At an optimum flow rate and vibration frequency, iron and Pt was completely extracted by using TBP and Aliquat336. At the same vibration frequency, iron and Pt was completely stripped by HCl and HClO 4 after adjusting the flow rate. Inthe case of extraction of HCl from the raffinate with TEHA, it was difficult to maintain the stability of the column extractor.A comparison of the operation results between column extractor and mixer-settler is reported. Key words : Pt, Fe, HCl, Karr reciprocating column 1. Introduction Spent catalysts are valuable secondary resourcesfor the platinum group metals (PGMs). Much workhas been done on the recovery of PGMs from spentcatalysts by hydrometallurgical method. First, PGMsare dissolved by chloride based solution and thenare separated by employing solvent extraction or * Received : July 9, 2013·Revised : August 7, 2013·Accepted : August 21, 2013Corresponding Author : Man-Seung Lee (E-mail : mslee@mokpo.ac.kr)Department of Advanced Materials Science & Engineering, Mokpo National University, 61 Dorim-ri, Chungkye-myun, Muan-gun, Chonnam, 534-729, KoreaTel : +82-62-450-2492 / Fax : +82-62-450-2498ⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.

The automatic control system of a multi-component nonequilibrium extraction process in the pulse column

The construction of the process dynamic model and the automatic control system of a plant constitute the two major objectives that allow the plant to be controlled in automatic mode. The model selected was the dynamic model of the nonequilibrium extraction process in the pulse column based on the mass transfer diffusion kinetics. The use of the molecular diffusion equation in the calculations is conditioned by the fact that diffusion limits the examined process of mass transfer and allows the kinetic processes of the reaction to be disregarded. For the developed model, spatial-temporal profiles were calculated for the distribution of uranium, nitric acid, plutonium, thorium, and neptunium concentrations throughout the height of the column extractor after a step change in the aqueous phase flow rate. The results of the head column automatic control system (ACS) synthesis are presented for the operation in the first and second cycles of irradiated nuclear fuel extraction purification. Several options for the system were examined, with their structural and parametric syntheses being performed on the basis of the column linear dynamic model. The findings of the research are presented in relation to the ACS with a constant-rate actuating mechanism. Several methods of development of the ACS software and hardware tools were studied for the implementation of the formulated requirements.

Strategies to remove water formed as by-product on the monoolein synthesis by enzymatic esterification performed on packed bed reactor

Different strategies to remove water generated on the monoolein synthesis by enzymatic esterification of oleic acid with glycerol were evaluated. Esterification reactions were catalyzed by Penicillium camembertii lipase immobilized on SiO2-PVA and runs carried out on a packed bed reactor (PBR) under continuous mode. The use of molecular sieves was the selected technique to remove the water formed, and for this purpose, two experimental setups were performed: (1) reactor packed with alternate layers of molecular sieves and immobilized lipase and (2) three reactors in series having a water column extractor between two immobilized packed beds, making it possible to replace the saturated molecular sieves by a regenerated one at a given time. Continuous run without applying dehydration techniques to remove the formed water was used as a control. The best performance was obtained using a water column extractor as verified by an increase in the monoolein formation from 22 to 35%. This strategy also provided a good performance of the bed reactor as a result of the high operational stability estimated for the immobilized derivative (half-life = 19 days).

A dynamic model of a multicomponent nonequilibrium extraction process in a pulsating column

The main principles of a dynamic model of a nonequilibrium extraction process in a pulsating column are considered. The results of calculating the space-time profiles of the distribution of the U, HNO3, Pu, Th, and Np concentrations along the height of a column extractor at a step change in the aqueous phase flow rate are presented.

Determination of Separation Capability of a Tray of Column Extractor

Determination of Separation Capability of a Tray of Column Extractor

PH measurement and control in solvent extraction using column contractors

pH measurement and control in a solvent extraction process using column extractors is a considerable challenge. This paper summarises the progress of WMT's understanding of the emulsion characteristics, hydraulic and kinetic regimes existing in the column extractors and their effects on pH measurement and control. Three sets of pilot scale test results are provided for a case study of nickel solvent extraction using Versatic 10 in a column extractor, with ammonia solution as the pH modifier. Initially the pH in extraction columns was controlled by directly dosing ammonia into the column to achieve the pH set point. The pH was measured in-situ by a pH meter inserted directly into the column. It was found that the ammonia tended to flow upwards with the organic rather than downwards with the aqueous flow, as would be expected, in an organic continuous operation. In the second test, the barren organic was pre-equilibrated with ammonia via an in-line mixer prior to entering the column. The pre-equilibrating ratio was proportional to the nickel pregnant liquor solution (PLS) tenor and the flowrate of the various phases. The final aqueous pH was used to tune the ratio. This resulted in a significant improvement in control of the pH in the column. In the third test, a combination of pre-equilibration and direct ammonia injection was used. The pH control in the column was very stable and a desirable pH profile in the column was achieved to maximise nickel recovery and reduce impurity co-extraction.

Current and Potential Developments in Methods for the Scale-Up and Design of Column Extractors

The current state-of-the-art is design and scale-up procedures for column-type liquid-liquid extractors is reviewed. This covers both the hydrodynamical factors which determine column cross-section and throughput, and those which influence mass transfer via drop-size and holdup, mass transfer coefficient, axial dispersion, drop interactions (i.e., breakage and coalescence), and Marangoni effects. The application of these principles to column design and scale-up is then discussed. It is concluded that for the present, both a matrix inversion method, and a simplified analytical method of adequate accuracy both for performance evaluation from pilot scale data, and for the design of both single-solvent and dual-solvent extractors, are the most suitable. Finally, the possibility is considered of developing more advanced methods based both on Monte Carlo procedures and on direct dynamic simulation by computer. Application Notes for Program ‘COLDSN’ and DUALSOLV appear in Appendix I and Appendix II, respectively.

Efficient and simple extraction of mouldy bran in a pulsed column extractor for recovery of amyloglucosidase in concentrated form

The recovery of amyloglucosidase from mouldy bran obtained from a solid-state fermentation system in a pulsed plug flow extractor was 86% with the use of 10 ml min −1 feed rate of the solvent and 87 min extraction time. The resulting extract volume was twice that of the weight of dry mouldy bran. An increase in the extraction time at the same feed rate resulted in improved extraction efficiencies, but the resulting extract was too dilute in nature. The use of a submerged column extractor for preventing possible channelling, together with the addition of calcium acetate to the feed solvent to reduce the viscosity of the extract, resulted in lower recoveries. The data indicate practical and economic advantages of pulsed plug flow extractors over the currently used percolation and multiple-contact counter-current leaching techniques.

Control of dispersed-phase volume fraction in multistage extraction columns

An ultrasonic technique is employed for the control of the dispersed-phase volume fraction (holdup) in liquid—liquid column extractors. The technique is tested for a multistage extractor of pilot-plant scale where the holdup is continuously monitored in all stages. The average holdup in the column, calculated from the profile, is considered as the control variable, while the agitation speed is used as the manipulated variable. The volumetric flow rates are the other operating conditions and are considered as disturbance variables. Adaptive and nonadaptive control are demonstrated by applying the Dahlin algorithm. By inspection of the holdup profile, information about the operation of the column with respect to flooding or phase inversion is provided. This information is processed for driving the holdup set point in the proximity of flooding where optimum operation usually occurs. For the first time, holdup is controlled over a wide range of values from as low as 10% to as high as 90% of the holdup value at flooding. The importance of the ultrasonic technique for the control of extraction columns is that it can be readily applied for safe operation at optimum conditions for any type of existing or new extractors.

Characterization of hydrodynamic parameters in a multistage column contactor

AbstractAccurate knowledge of hydrodynamic parameters is of major importance for the performance study of liquid‐liquid column extractors. The effects of operating parameters on dispersed phase holdup profiles, drop size distributions, and axial mixing in both phases were investigated in a 127 mm diameter multistage contactor of pilot plant scale for the toluene‐water physically equilibrated system. Correlations for the mean holdup, the mean drop size, and the continuous phase backmixing were obtained. A stronger dependence of holdup and drop size on the operating conditions and especially on the agitation speed was observed as compared to previous investigations for the same type of contactor. The axial mixing for the single phase flow was found to follow adequately an existing correlation, while the continuous‐phase axial mixing in two‐phase flows showed some deviations from other existing correlations. Also, flooding criteria, important for the control of the extraction process, were determined based on the shape of the holdup profiles.