In this work, the drying kinetics of ginger (Zingiber officinale Roscoe) was studied considering the shrinkage effect. The experimental data were obtained using three different temperatures (40, 60, and 80 degrees C). For the determination of shrinkage, two cutting orientations were employed. The volumetric and thickness shrinkage was evaluated by direct measurement. The shrinkage showed two periods during drying and had a considerable effect on the drying rate. An equation that relates the changes in the drying area as a function of the moisture content was determined. During drying, ginger showed only a falling rate period and exhibited a characteristic drying curve.

The use of supported liquid membrane extraction for recovery and separation of rare-earth elements (REEs) has been investigated. Experiments have been carried out using the different configurations: (1) standard hollow fiber supported liquid membrane operation (HFSLM), (2) renewal liquid membrane operation (HFRLM), and (3) emulsion pertraction technology (EPT). The experiments were performed in pilot scale using a hollow fiber module with a mass transfer surface area of 8 m2. Synthetic feed solution was used with compositions based on a process for recovery of REE from an apatite concentrate. The total concentration of REE in the feed was varied from 1 to 22 mM REE and the pH was varied in the range 1.5–3.2. Di(2-ethylhexyl) phosphoric acid (D2HEPA) diluted in kerosene, 10% (v/v), was used as the organic membrane solution, and 3 M HCl was used as stripping solution. In supported liquid membrane extraction, the extraction performance is governed by both the kinetics of REE transport through the membrane and by thermodynamics. The effect of feed composition on the selectivity and transport of REE through the liquid membrane have been investigated. The results show that the liquid membrane is more selective toward the heavy REE at lower pH values and higher REE concentration. HFRLM shows a higher transport rate than HFSLM, while the HFSLM configuration gives a higher selectivity toward individual REE. The membrane performance in HFSLM configuration rapidly decays with time, while in the HFRLM and EPT configurations, the performance is much more stable. Possible mechanisms for decaying membrane performance are discussed, and gel formation is identified as being of significant importance. Gel formation is observed at an organic loading above ∼46% for Nd, 38% for Y, 46% for Dy, and 65% for Er. The work performed in this study serves as an initial step to demonstrate that HFRLM and EPT can provide stable operation and be feasible options for processing of REE liquors. A process flow diagram for the recovery of the REE, present in the apatite concentrate, in three fractions is proposed based on the results from this study.

Separation selectivity of the mixture Yttrium-Neodymium-Dysprosium using Bis (2-ethylhexyl) hydrogen phosphate (D2EHPA) as extractant in a flat sheet supported liquid membrane was studied by simulations. A new definition of selectivity and a diffusional-kinetic transient model were used in the calculations. Resistance distribution between the phases, stripping phase pH, extractant concentration and initial feed concentration have great influence on selectivity and process time and their appropriate management would improve separation. The analysis of selectivity using the present model would be a useful tool to design a multistage process aimed at the separation of a multicomponent mixture of rare earth elements into its constituents.

Separation and purification of rare earth elements (REE) is of great importance due to the varietyof their technological applications. In this context, liquid membrane separation stand out as an alternative to traditional techniques in order to selectively separate and concentrate REE. Some of the most significant advantages of the liquid membrane technologies are the minimum liquid membrane inventory and the low power consumption (V. S. Kislik 2010). However, membrane instability can be a significant problem for industrial application and the mechanisms behind membrane instability are poorly understood.This study analyses the separation of rare earth elements by means of liquid membranes with the final objective of recovering REE from an apatite concentrate (M. Alemrajabi, 2015, M.Mohammadi, 2015). In this study, the feed phase will consist of an aqueous phase containing REE, the membrane phase will contain organic solvent and carrier (mainly D2EHPA and EHEHPA), and the stripping phase will be a hydrochloric acid solution. In order to analyse the suitability of liquid membranes in the extraction ofREE, a deeper insight into the mechanisms causing instability is needed. In this study, surface tension is considered as the key factor of Marangoni instabilities and spontaneous emulsification (A. M. Neplenbroek 1992. H-D. Zheng 2009, F. F. Zha 1995). The influence of capillary forces and the effect of mass transfer through the membrane will be examined. Furthermore, a comprehensive evaluation of mass fluxes, separation efficiency and membrane performance on a wide range of operating conditions will be conducted in order to optimise the separation process. This study is expected to provide valuable information for the design of more stable and efficient liquid membrane processes.

The equilibrium separation of trivalent rare earth elements (Nd(III), Dy(III), and Y(III)) from hydrochloric acid solution by di-(2-ethylhexyl) phosphoric acid (D2EHPA) and 2-ethylhexylphosphonic acid mono-2-ethyl hexyl ester (EHEHPA) separately and in mixtures has been studied. The effect of extractant concentration, extractant mixture composition and solution acidity has been investigated. The results show that a mixture of D2EHPA and EHEHPA provide a better separation of Y(III) from Dy(III) when the total extractant concentration is 0.06 and 0.09 mol/L, while the separation is better using pure EHEHPA at higher extractant concentration (0.15 mol/L). The separation of Nd(III) from Y(III) and Dy(III) is higher using pure D2EHPA (0.06 and 0.15 mol/L). The results show that for the complexation of the Nd(III) ions approx. 1-2 hydrogen ions/rare earth element (REE) ion are released to the aqueous phase upon binding approximately 1 extractant dimer on average. For the complexation of Y(III) and Dy(III) ions 2-3 hydrogen ions are released upon binding approximately two extractant dimers on average. Accordingly, under the conditions of this work the complexation involves not only extractant molecule dimers but also monomers or aggregated REE species to some extent, and a fraction of the REE is extracted as chloride complexes. (C) 2015 Elsevier B.V. All rights reserved.

A mathematical model for the drying of grain in a continuous vibrating fluidized bed dryer was developed. Simple equipment and material models were applied to describe the process. In the plug-flow equipment model, a thin layer of particles moving forward and well mixed in the direction of the gas flow was examined. Mass and heat transfer within a single wet particle was described by effective transport coefficients. Assuming constant effective mass transport coefficient and thermal conductivity, analytical solutions of the mass and energy balances were obtained. The variation in both transport coefficients along the dryer was taken into account by a stepwise application of the analytical solution in space intervals with averaged coefficients from previous locations in the dryer. Calculation results were in fairly good agreement with experimental data from the literature. However, the results depend strongly on relationships used to determine heat and mass transfer coefficients; because the results from correlations found in the literature vary considerably, the correlations should be adapted to the specific equipment in order to obtain reliable results.