Flowsheet, solvent

Absorption. If possible, a component which already exists in the flowsheet should be used as a solvent. Introducing an extraneous component into the flowsheet introduces additional complexity and the possibility of increased environmental and safety problems later in the design. 

Chemical Flowsheet Basic unit operation selection with flow rates, conversion factors, temperatures, pressures, solvents and catalyst selection Process synthesis route Laboratory and pilot scale trials Knowledge of existing processes... 

Figure 5.14 Generalized solvent extraction process flowsheet.

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-... 

Commercial-scale application of solvents coming under the category of neutral reagents is largely found as applied to the nuclear industry materials, as in example, for the separation and refining of uranium, plutonium, thorium, zirconium, and niobium. A process flowsheet for extracting niobium and tantalum from various resources is shown in Figure 5.23. It will... 

T. K. Mukherjee and C. K. Gupta, Flowsheets Development for Recovery of Nonferrous Metal values from Secondary Resources by Solvent Extraction, Proceed, of a Symposium - Emerging Separation Technologies for Metals II Sponsored by the Engineers Foundation Conference and the National Science Foundation held at Kona, Hawaii, June 16-21,1996. 

The process flowsheet for a cellulose acetate fibers process is shown in Figure 19.12. Solvent is removed from the fibers in a dryer by recirculating air. The air is cooled before it enters an absorber where the solvent is absorbed in water. The solvent-water mixture is separated in a distillation column and... 

The synthesis of reaction-separation systems. The recycling of material is an essential feature of most chemical processes. The use of excess reactants, diluents, solvents or heat carriers in the reactor design has a significant effect on the flowsheet recycle structure. Sometimes, the recycling of unwanted byproduct to the reactor can inhibit its formation at the source. 

Figure 5 A simplified flowsheet and materials balance for the recovery of copper from oxidic and transition ores by heap leaching, solvent extraction and electrowinning.

Acylpyrazolones (24) also form neutral /3-diketonate-type complexes suitable for extraction of a range of metals into organic solvents and have been considered171 as alternatives to LIX 54 for use in ammoniacal leach circuits. Although they are stronger extractants than LIX 54,4,172 the low solubility of their metal complexes has limited their usefulness in Cu recovery.171 The structurally related diazopyrazolones (25) have pHi/2 values, ca. 3.7, and their chemical stability on contact with ammoniacal feeds meets the requirements of the flowsheet outlined above, but their very intense colors may restrict their use as commercial extractants.173,174 The bulk of the arylazo... 

Figure 10 A typical solvent extraction flowsheet for PGM refining.290,291...

Nogueira, C. A. Delmas, F. New flowsheet for the recovery of cadmium, cobalt and nickel from spent Ni-Cd batteries by solvent extraction. Hydrometallurgy 1999, 52, 267-287. 

Figure 16.32. Flowsheet for drying polypropylene by fluidising with a hot stream of solvent vapour— ...

The second part deals with applications of solvent extraction in industry, and begins with a general chapter (Chapter 7) that involves both equipment, flowsheet development, economic factors, and environmental aspects. Chapter 8 is concerned with fundamental engineering concepts for multistage extraction. Chapter 9 describes contactor design. It is followed by the industrial extraction of organic and biochemical compounds for purification and pharmaceutical uses (Chapter 10), recovery of metals for industrial production (Chapter 11), applications in the nuclear fuel cycle (Chapter 12), and recycling or waste treatment (Chapter 14). Analytical applications are briefly summarized in Chapter 13. The last chapters, Chapters 15 and 16, describe some newer developments in which the principle of solvent extraction has or may come into use, and theoretical developments. 

In many synfuel refinery flowsheets, the acid-gas partial pressure is borderline between obvious preferance for hot carbonate and physical solvent-based acid-gas removal systems. In these... 

Extractive Distillation Recovery of Isoprene. A typical flowsketch and material balance of distillation and solvent recovery towers for extracting isoprene from a mixture of cracked products with aqueous acetonitrile appears in Figure 13.26. A description of the flowsheet of a complete plant is given in Example 2.10. In spite of the fact that several trays for washing by reflux are provided, some volatilization of solvent still occurs so that the complete plant... 

On the modem plants employing the Bufflex flowsheet, uranyl sulfate is stripped from the resins with the bisulfate anion. The eluate contains about 1 M sulfuric acid since this is the optimum concentration for the subsequent solvent-extraction process at lower acid concentrations, the tertiary amine in solvent extraction is only partially ionized, which reduces its capacity for uranyl sulfate, whereas at higher acid concentrations the bisulfate anion begins to compete with the uranyl sulfate anion for tertiary amine functional groups. 

Many variants of the Purex (Plutonium Uranium Reduction Extraction) process23S based on TBP extraction have been developed but a basic outline flowsheet is illustrated in Figure 38. This shows the so-called early split flowsheet most commonly used in existing plants. It involves the separation of the uranium and plutonium using two different back-extractant streams during the first solvent extraction cycle. Additional solvent extraction cycles are then carried out independently on the uranium and plutonium streams to effect further purification. An alternative arrangement is the iate split flowsheet used at the Cap La Hague plant in France, and the... 

Windscale II plant in the UK. In this the uranium and plutonium are back-extracted together in a first cycle of decontamination. They are then separated in a second cycle of solvent extraction and independent back-extraction. The factors affecting the choice of flowsheet type have been reviewed and criticality control is an important consideration in the process design.286... 

TBP is a sufficiently powerful extractant for actinides that it may be used in diluted form. Dilution improves the hydrodynamic properties of the solvent, allowing more complete and rapid phase disengagement. Typically concentrations of 20-30 v/o TBP in OK are used in process flowsheets. Although TBP is relatively stable as an extractant, radiolysis does lead to the formation of some acidic phosphate esters, HDBP and H2MBP, which can impair process performance.289 An aqueous alkali wash of the recycled solvent is usually carried out to remove those by products. Radiolytic degradation of the diluent in the presence of nitric acid can result in the formation of hydroxamic acids,290 which can lead to fission product retention by the organic phase. Again the solvent wash is used to prevent the accumulation of such species. A comprehensive account of the industrial utilization of TBP has recently been published.291... 

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