Solvent extraction equipment

The principal functional requirements of a solvent extraction contactor are as follows  

To develop sufficient interfacial area to promote transfer of extractable components between phases 

To facilitate countercurrent flow of the two phases, without excessive entrainment Additional considerations in selecting contacting equipment are as follows  

It should have flexibility to operate under varied conditions of flow ratios and concentrations. 

It should be mechanically dependable and easy to operate and maintain. 

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Instrumentation on the solvent extraction equipment will usually consist of recording flow and recording temperature controllers on the feed stream, a pressure controller on the raffinate exit line, temperature recorders on the column intercoolers, and a liquid level recording controller at the liquid-liquid interface to set the extract layer withdrawal rate. 

When evaluating whether or not an aqueous and organic (solvent) pair is suitable for carrying out a solvent extraction, the most important characteristic is the distribution ratios of the components to be extracted and of those to be left in the fluid. Once the distribution ratios are found to be favorable, the immiscible liquid-liquid pair must be characterized to determine if the pair can be used in commercial solvent-extraction equipment. This characterization is best done by the batch dispersion-number test (Leonard, 1995). This test can be performed easily and quickly with no special equipment. If the results are favorable, the densities of the two phases need to be considered. If the difference is less than 10%, plant operation could be difficult. As a rule of thumb, the density difference should be 15% or greater. The liquid viscosity is important in that more power will be required to turn the rotor if the viscosity is higher. The liquids also need to be able to flow easily from stage to stage. 

Solvent extraction has long been established as a basic unit operation for chemical separations. Chapter 7 summarizes the effects of temperature, pH, ion pairs, and solvent selection on solvent extraction for biomolecules. Solvent extraction of fermentation products such as alcohols, aliphatic carboxylic acids, amino acids, and antibiotics are discussed. Enhanced solvent extraction using reversed micelles and electrical fields are also discussed. Solvent-extraction equipment and operational considerations are adequately covered in this chapter. 

Introduction of the expander has enabled extraction plants to handle additional seed species, with purchase of only minimal cleaning and dehulling equipment where needed. Prepress-solvent extraction facilities are being replaced by expander-direct solvent extraction equipment, leaving two basic extraction processes in modern large volume oilseed extraction plants expander-direct solvent extraction, and hard press for applications... 

The American company, French Oil Mill Machinery Company of Piqua, Ohio, developed continuous solvent extraction plants starting in 1939, using a multistage BoUman-type percolation extractor (3). Soon thereafter, the Belgian Company, Extraction De Smet, started manufacturing continuous multistage belt-type extractors in 1945. V.D. Anderson of Cleveland, Ohio, joined the solvent extraction equipment supply market in 1948 with continuous HUdebrandt-type immersion extractors (5). 

Solvent extraction equipment suitable for use in the separation of uranium isotopes. 

The advantage of these fluidized bed columns is the relatively low capital cost, low operating cost, small space requirement, simple instrumentation and control compactability with conventional solvent extraction equipment. Only those systems that can accommodate slurries with suspended solids are commercially feasible for biotechnology and fermentation operations. Otherwise, the small volume of fermentation feedstreams which need to be processed are not the scale of operations necessary to make continuous ion exchange processes cost effective. 

There are basically two designs of solvent extraction equipment, the percolation type, in which the... 

A wide variety of solvent extraction equipment has been developed for use in counter-current, liquid-liquid extraction processes. In general they divide into vertical and horizontal types, referred to as columns or mixer-settlers respectively. In both cases, the object is to obtain suitable conditions for the transfer of solute from one phase to the other as rapidly and efficiently as possible. 

Small-scale solvent extraction is often done batchwise in separation funnels or test tubes. However, for more elaborate extraction studies and industrial processes continuous extraction is usually preferred. All continuous solvent extraction equipment consists of a mixer for phase contact and mass transfer and a separation part for phase disengagement. The main types of continuously working apparatus are ... 

There are two main classes of solvent-extraction equipment, vessels in which mechanical agitation is provided for mixing, and vessels in which the mixing is done by the flow of the fluids themselves. The extraction equipment can be operated batchwise or operated continuously as in absorption and in distillation. 

Low-Inventory Process Equipment. Solvent extraction equipment and dissolvers that have very high throughput but low Inventory have been developed. The low-inventory feature enhances neutron leakage and facilitates protection against the gradual accumulation of large masses of fissile material. 

In the original PUREX process (Choppin, Khankhasayev, and Plendl, 2002 Morss et al., 2006 NEA, 1997 Richter et al., 2006 Selvaduray, 1978), hexavalent uranium (UO or U(VI)) and tetravalent plutonium (Pu or Pu(IV)) are extracted from a nitric acid solution of dissolved irradiated fuel by an organic phase composed of TBP diluted to nominal 20%-30% (by volume) with a normal paraffinic hydrocarbon (NPH) organic diluent such as odorless kerosene, or dodecane. Note that the diluent is required only to maintain the physical characteristics of the organic phase (primarily viscosity and density) in a workable range for use in the salient solvent extraction equipment (Herbst, Baron, and Nilsson, 2011,141-175). 

G. W. Stevens and H. R. C. Pratt, Solvent extraction equipment design and operation Euture directions from an engineering perspective. Solvent Extr. Ion Exch., 18, 1051 (2000). 

In processing homogeneous reactor fuel, a transition from a heavy- to a natural-water system is desirable if final processing is to be performed in conventional solvent extraction equipment. Such a transition must be accomplished with a minimum loss of D2O and a minimum contamination of... 

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