Relation between oil–water flow and extraction performance in liquid–liquid countercurrent centrifugal extractors with Taylor vortices

Abstract

A countercurrent centrifugal extractor with an inner rotor and a stationary outer wall has been developed in which aqueous and organic phases flow countercurrently between two walls. The formation of stable Taylor vortices in the gap makes multistage extraction possible. Understanding the relation between flow state and percent extraction is important for achieving a greater number of theoretical stages in a single extractor. Hence, oil-water countercurrent flow is measured by ultrasonic velocity profiling, without disturbing the flow, under different feed rates of solutions and rotating speeds of the inner rotor. In continuous extraction tests, Zn 2 + in nitric acid and di-(2-ethylhexyl)-phosphoric acid diluted by n-dodecane are used. Measurement results are verified by numerical simulation. Finally, a correlation chart of flow patterns and operating conditions is prepared.

High-performance extraction operation using emulsion flow protected by surfactants in a liquid-liquid countercurrent centrifugal extractor

“…The extractor is the same as the one in our previous study, and a detailed discussion of the composition, such as the material of the inner rotor, has already been reported [6]. In the present paper, the stability of emulsion flow and the extraction performance are discussed.…”

“…In the organic phase, the concentration of zinc-HDEHP complex in each bath is Y Zn,j−1 , Y Zn,j , and Y Zn,j + 1 . In this case, two types of equations have to be derived, namely mass balance equations for the jth bath Equations (4) and (5) and an equation for the extraction equilibrium constant in each bath Equation (6).…”

“…However, in the case of the geometry and operating conditions of our extractor, the influence of these parameters is negligible. Nakase et al clarified the relation between flow patterns of dispersed organic phase, operating conditions, and extraction performance by continuous extraction experiments and flow measurements by the ultrasonic velocity profiler method [6]. They also used this type of extractor for fast separation of europium and samarium, which are otherwise difficult to separate due to their similar chemical characteristics and preliminarily demonstrated a multistage separation extraction with a single centrifugal extractor [7].…”

Multi-staging for extraction of cesium from nitric acid by a single liquid–liquid countercurrent centrifugal extractor with Taylor vortices

“…The extractor used in this study is the same as in our previous studies [17][18][19]. In this study, we compared the extraction performance of Cs from nitric acid in batch and continuous extraction case in various conditions.…”

“…In light of this background, we have developed a liquid-liquid countercurrent centrifugal extractor that induces a series of Taylor vortices and we have successfully demonstrated the concept of extraction with multiple theoretical stages by the centrifugal extractor with di(ethylhexyl) phosphoric acid, which has fast extraction kinetics [17][18][19][20][21]. In this study, we focused on Cs separation from nitric acid with BOBCalixC6, which has slow extraction kinetics.…”