Countercurrent Extraction System Research Articles

Nitric acid removal via mini-extractors

Industrial effluents often contain toxic, corrosive, and/or oxidizing acids that have a significant risk of causing major injuries to people or damage to the environment. The risk increases with increases in residence time and volume. Rapid and inherently safe methods, i.e. high-efficiency and small-volume devices, are therefore necessary to remove these acids from the effluents. In the study, two mini-extractors with very small volumes were developed and demonstrated to remove corrosive and oxidizing nitric acid from an aqueous solution using solvent extraction. A co-current mini-extractor having a residence volume of 0.172 mL was initially designed using the Coanda effect and experimentally investigated. The experimental results indicated that a nitric acid extraction extent of 97.5% was achieved even at a high total throughput of 120 mL/min. Furthermore, the co-current mini-extractor was adapted to construct a passive and high-throughput counter-current extraction system with a residence volume of 7.51 mL. The nitric acid recovery efficiency was 2.30 times that in the co-current extraction equilibrium, and its total throughputs were one to three orders of magnitude higher than those in the reported passive counter-current extraction systems using micro-extractors. Hence, it indicates that mini-extractors are available for the rapid removal of hazardous acids from effluents.

Bio-inspired counter-current multiplier for enrichment of solutes

Improving the efficiency of gas separation technology is a challenge facing modern industry, since existing methods for gas separation, including hollow-fiber membrane contactors, vacuum swing adsorption, and cryogenic distillation, represents a significant portion of the world’s energy consumption. Here, we report an enhancement in the release rate of carbon dioxide and oxygen of a thermal swing gas desorption unit using a counter-current amplification method inspired by fish. Differing from a conventional counter-current extraction system, counter-current amplification makes use of parallel capture fluid channels separated by a semipermeable membrane in addition to the semipermeable membrane separating the capture fluid channel and the gas release channel. The membrane separating the incoming and outgoing fluid channels allows gas that would normally exit the system to remain in the desorption unit. We demonstrate the system using both resistive heating and photothermal heating. With resistive heating, an increase in release rate of 240% was observed compared to an equivalent counter-current extraction system.

Recovery of thorium (IV) from leached monazite solutions using counter-current extraction

A flow sheet was developed to recover thorium from Egyptian monazite sands. The results of a detailed investigation on the extraction and stripping of thorium in the hydrous oxide are obtained after alkaline dissolution followed by leaching with alkaline carbonate solutions. This cake was dissolved in 4 M HNO 3 and thorium was extracted selectively by a counter-current extraction system using a mixer–settler contactor and Aliquat-336 in kerosene as extractant. The results show that 2 h of continuous operation are necessary to reach the steady state condition for the process. The extraction efficiency is found to be 80% and the stripping efficiency is 82%.

Simulation of the development automatization control system for rare earth extraction process: Combination of ESRECE simulation software and EDXRF analysis technique

Recently, the requirement of developing the automatic control for rare earth extraction processes has been attracting a lot of attention. However, due to the similarity of chemical physical properties of rare earth, the separation of these elements requires a great number of stages of mixer-settles. The multistage countercurrent extraction system, consisted of two immiscible flowing phases—the organic phase and the aqueous phase and the variable composition take place stage by stage. This plant generally requires a continuous control the status of the separation process and its efficacy, in order to prevent appearing an ‘out-of-specification product’ or a high raffinate value. For studying the steady or dynamic performance of stage-wise processes, and establishing the relative controlling system, the on-line EDXRF analytical technique and ESRECE simulation system were used in our laboratory.

Solvent extraction of oil from soybean flour I— extraction rate, a countercurrent extraction system, and oil quality

Measurements of rates of oil extraction from either fine flour or soybean flakes in a column showed that oil extraction from flour was dependent on the volume of solvent, but oil extraction from flakes depended on time of contact rather than volume of solvent. We interpreted the data to mean that oil was being washed out of the fine flour with little diffusion involved, whereas in flakes, the limit on rate was diffusion of the solvent into and out of the tissue.Fine full fat flour worked well in a batchwise countercurrent extraction system with mixing and centrifugal separation. Because the oil dissolved immediately and reached equilibrium rapidly, the actual material balance was close to calculated values. However, due to the large hold‐up volume, the separation of miscella from the meal required several mixing and separation stages. The oil resulting from this countercurrent extraction system had a superior quality with 37 ppm phosphorus, 0.08% free fatty acids, and a light color.

Computer modelling of the solvent extraction of iron by versatic acid from aluminium nitrate solutions

The development of a chemically based computer model of the extraction of ferric iron from concentrated aluminium nitrate solutions by Versatic 10 is outlined. The model uses previously determined equilibrium constants to calculate the distribution of iron in the various metal complexes present in the organic phase, together with empirical relationships for the pH changes occurring in the aqueous phase during extraction. A mean error of ±13% was found between computer predicted and experimentally determined organic phase iron concentrations for a four-stage counter-current extraction system. It is concluded that iron extraction by Versatic 10 is a technically feasible method of achieving aluminium nitrate with a sufficiently low iron content to enable the production of smelter grade alumina.

Conceptual Design of A Self-Cooled FLiBe Blanket

There are a number of attractive features for Flibe, such as: (1) low-pressure operation, (2) relatively inert to air and water, (3) low activation, (4) high-temperature stability, and (5) low electrical conductivity. If these features can be incorporated into a self-cooled blanket, a simple, high-performance, and reliable blanket may be possible. Detailed analysis has uncovered some attractive features and some potential problems. A highly compact and efficient primary loop can be developed with a conversion efficiency of 46%. The blanket is designed to be inherently safe for at least a 4.7 MW/m/sup 2/ neutron wall loading. Since no reflector is needed, the mass utilization is very high. A similar blanket for MINIMARS has a mass utilization figure of 138 kW(e)/tonne, the highest among the four blanket candidates. In addition, a very simple blanket can be designed. There is, however, concern about the lithium doping idea for tritium control. The issues cannot be resolved until experimental verification is available. However, if a vanadium alloy is used for the structural material, a large fraction of tritium will permeate back through the first wall to the plasma. Permeation through the first wall will result in a tritium partial pressure of < 10/sup -4/more » Torr. If this is the case, the primary blanket tritium recovery system can be combined with the plasma exhaust system. A highly efficient tritium cleanup system will still be required to reduce the tritium permeation problem. A countercurrent extraction system can be used for tritium cleanup.« less

Counter Current Extraction System for Tritium Recovery from 17Li-83Pb

A counter current extraction system is proposed here to recover tritium from 17Li-83Pb. The multiple stage extraction system is used to reduce the resistance to the molecular diffusion in the liquid phase, while a counter current helium purge gas is used to reduce the resistance in the gas phase. To reduce the purge gas requirement and alleviate the tritium containment problem, hydrogen is added to the purge gas. An isotope separation system is designed to separate the hydrogen from the tritium.

Proposition Concerning Desulfurization of Mineral Oils

It was about 30 years ago when I invented a new process to obtain phenols, or oxygen compounds, from man-made petroleum (made by coal hydrogenation) containing phenols by super heated water extraction. I obtained a Japanese patent on this invention and made it known to the public. Observing the similarity between the nature of oxygen and that of sulfur in their respective compounds, I took aim at the possibility of desulfurizing petroleum by super heated water extraction. I, then, arranged preliminary experiments. In an autoclave at 300°C, 40‰ desulfurization of heavy oil was proved ex-perimentally.Based on my old experience, I had once expected that I would obtain even a higher efficiency for this desulfurization if I would use a counter-current extraction system. I made experiments with a simple made-shift apparatus. However, due to a deficient feeding device of counter-current the experiment did not effect expected results, the efficiency of which was only 30‰ desulfurization of light oil (vacuum distilled) at 230°C.Though the experiment did not end up to my satisfaction, I obtained from it con-ditions necessary for the industrialization of desulfurization of mineral oils. I am also convinced now, that the desulfurization of mineral oils will be easily realized by means of super heated water extraction, if I had necessary apparatus with perfect feedding system of counter-current. Furthermore, I am also certain that a new field will be developed where organosulfur compounds obtained by said extraction method will find various useful applications.

Separation of ions by alteration of the concentration of the ligand in a discontinuous countercurrent extraction system

A new technique in Craig-type liquid-liquid, discontinuous, countercurrent solvent extraction was developed. In this, the ligand concentration in the extraction train was altered at several points, causing non-equivalent changes in the extractability of the ions being separated. This allowed quantitative separation of a mixture with a minimum number of transfers, thereby keeping the solvent volume to a minimum. The technique was applied to achieve total or partial separation of a number of elements, using methyl isobutyl ketone as the solvent and hydrochloric acid as the ligand. A computer programme was developed for calculating the distribution of a solute in an extraction train operating under these conditions.