Extraction process description

Anhydrous Acetic Acid. In the manufacture of acetic acid by direct oxidation of a petroleum-based feedstock, solvent extraction has been used to separate acetic acid [64-19-7] from the aqueous reaction Hquor containing significant quantities of formic and propionic acids. Isoamyl acetate [123-92-2] is used as solvent to extract nearly all the acetic acid, and some water, from the aqueous feed (236). The extract is then dehydrated by azeotropic distillation using isoamyl acetate as water entrainer (see DISTILLATION, AZEOTROPIC AND EXTRACTIVE). It is claimed that the extraction step in this process affords substantial savings in plant capital investment and operating cost (see Acetic acid and derivatives). A detailed description of various extraction processes is available (237). 

The monograph on zinc is a valuable general reference on zinc technology (3). Furthermore, detailed descriptions of extractive processes, resource data, and environmental- and energy-related papers from symposia of the Metallurgical Society of the AIME are a rich source of information (4—7). 

The coupling of supercritical fluid extraction (SEE) with gas chromatography (SEE-GC) provides an excellent example of the application of multidimensional chromatography principles to a sample preparation method. In SEE, the analytical matrix is packed into an extraction vessel and a supercritical fluid, usually carbon dioxide, is passed through it. The analyte matrix may be viewed as the stationary phase, while the supercritical fluid can be viewed as the mobile phase. In order to obtain an effective extraction, the solubility of the analyte in the supercritical fluid mobile phase must be considered, along with its affinity to the matrix stationary phase. The effluent from the extraction is then collected and transferred to a gas chromatograph. In his comprehensive text, Taylor provides an excellent description of the principles and applications of SEE (44), while Pawliszyn presents a description of the supercritical fluid as the mobile phase in his development of a kinetic model for the extraction process (45). 

The present description pertaining to copper refers to solvent extraction of copper at the Bluebird Mine, Miami. When the plant became operational in the first quarter of 1968 it used L1X 64, but L1X 64N was introduced in to its operation from late 1968. The ore consists of the oxidized minerals, chrysocolla and lesser amounts of azurite and malachite. A heap leaching process is adopted for this copper resource. Heap-leached copper solution is subjected to solvent extraction operation, the extractant being a solution of 7-8% L1X 64N incorporated in kerosene diluent. The extraction process flowsheet is shown in Figure 5.20. The extraction equilibrium diagram portrayed in Figure 5.21 (A) shows the condi-... 

The LLE for ILs and common solvents such as alcohols is very important for developing ILs for liquid-liquid extraction processes. Previous studies in many laboratories have shown this potential. Most of the measured mixtures were of IL + short chain alcohol) binary systems. It is well known that an increase in the alkyl chain length of the alcohol resulted in an increase in the UCST. Nevertheless, the solubilities of many ILs were measured in 1-octanol (important value for the description of bioaccumulation) [14,50-54, 79,98-100,112,127,133]. The other short chain alcohols were pointed out earlier. 

ICFs Commercial Process. In 1960 ICI constructed a concentration plant using this extractive distillation process (18) with a capacity of 16,000 tonnes/ annum of product acid (99.5 wt% HNO3) which has subsequently been extended. A flowsheet is given in Figure 8, and the process description is as follows. 

Rather than an in-depth technical description of the mechanics of extraction, this section presents briefly a typical infusion process, focusing on the factors that make extracts different from single-chemical components. Extracts by then nature are complex mixtures of (often) diverse active compounds contained within a plant matrix which are brought into solution by the extraction process. The aim of the extractor is to produce, over a period of time, batches of an extract meeting a customer s individual specification with as little variation as possible. There are parameters over which the extractor has some control, and these can be used to help achieve product consistency and also to fine-tune an extract to a particular customer s needs. 

Figure 17. An empirical model was developed to describe the extraction process, taking account of the observation that [U02(DBP)2(HDBP)2] was the predominant uranyl species in the organic phase at aqueous phase acidities of less than 2 M, while [U02(N03)2(HDBP)2] predominated at higher acidities. The curves derived from this model, and a revised model which took into account the presence of other organic phase species such as H[U02(N03)3] (HDBP), are shown in Figure 18. The latter model gave a good description of the system in the aqueous phase acidity range 1 -7 M.

For all the systems studied, it is now acknowledged that the self-assembling properties of both the extractant and the metal or acid-extractant complexes produce polar cores that are unstable due to short-range attractive interactions. The speciation of supramolecular structure is thus highly important for further progress toward a complete description of liquid/liquid extraction processes (38). 

Studies on the solvent extraction of actinide ions by different combinations of extractants have been reviewed. Various equilibria involved in the extraction processes and the formation of the extract-able complexes have been considered along with their equilibrium constant data. Various methods which are useful in establishing the composition and the nature of the extractable complexes are presented. The data on isolation and structural studies of some complexes, involved in synergic extraction, are also included. A brief description of the different areas in which synergic extraction is finding application is also given. Many combinations of extractants, where the studies conducted are very few but, which are likely to yield enhanced extractions are indicated. Areas of research, both from the academic and applied points of view, which require attention are suggested. 

In many of the examples presented in Table XIV, the existence of reversed micelles (331,231,231,211,231,HI,221,or micro-emulsions (349-352) is implicated and their presence is an important factor which influences the characteristics of a particular extraction process. Often, quantitative descriptions of such extractions is difficult due to the fact that many of the reversed micellar systems formed undergo an indefinite type of self-association in... 

Description This butadiene extraction process was originally developed by Shell Chemicals. It is offered under license agreement by Kellogg Brown Root, who has updated and optimized the process to reduce capital and operating costs. 

A mixture containing 50.0 wt% acetone and 50.0 wt% water is to be separated into two streams— one enriched in acetone, the other in water. The separation process consists of extraction of the acetone from the water into methyl isobutyl ketone (MIBK), which dissolves acetone but is nearly immiscible with water. The description that follows introduces some of the terms commonly used in reference to liquid extraction processes. The process is shown schematically below. 

The extraction and back-extraction steps take place consecutively, connected by the concentration of the metal-extractant complex species in the organic phase. The description of the back-extraction process is carried out using similar equations to those used in the extraction process. The equilibrium of the interfacial reaction between the organic complex species and the back-extraction agent is applied in this case. 

Solute transport through the LM enhances by water-immiscible species, dissolved in the solvent (water immiscible also) and selectively interacted with solutes. These species are named carriers and transport is facilitated, or membrane-mediated, or carrier-enhanced, or... (authors use different terms for the same phenomenon). Most LM carriers are originally extractants developed for solvent extraction processes. The reader can find their descriptions in the Solvent Extraction Handbooks, for example [88, 89]. Many new carriers are developed specially for LM (see Section 4). The use of LM with carriers offers an alternative to solvent extraction for selective separation and concentration of metal ions from dilute solutions. 

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