Materials science extraction process

The coruiection between supercritical fluids and clean separations is, however, more recent. It appears during the 1970s, when it was shown that supercritical carbon dioxide could become an important extraction solvent for food-related applications. Since then, the field has expanded enormously. A wide range of fundamental studies have been pubhshed and many patents submitted, with potential applications in separation processes, chemistry, and materials science. Many books and reviews have been pubhshed on different aspects of supercritical fluids. 

Study of membrane extraction processes is a matter of primary importance for intensive development of separation and concentration methods of different nature substrates, especially such valuable ones as rare and scattered metals. The imique properties of rare earth metals (REM) allow using them in different realms of modem science and technology when making selective catalysts, magnets (samarium and neodymium), optical systems, luminophors, and ceramic capacitors. REMs are used in metallurgy for production of special cast iron grades, steel, and nonferrous metals alloys. REM additives increase quality of metallurgical products improve their properties, particularly shock resistance, viscosity, and corrosion resistance. Such materials are used primarily in aerospace industry. Extraction of REM from minerals is a complex process. 

SCFs are a class of promising green solvents in the development of environmentally benign chemical processes. Scientists and engineers have been very much interested in SCF science and technology in the last decades because of their unique properties and great potential of applications in different fields [4], such as extraction and separation [5], chemical reactions [6], and materials science [7]. Supercritical (sc) or compressed CO2, which is nontoxic, abundant, and nonflammable, can also be used to tune the physical properties of liquid solvents because its solubility in Hquids changes continuously with pressure and/or temperature [8]. 

The scientific basis of extractive metallurgy is inorganic physical chemistry, mainly chemical thermodynamics and kinetics (see Thermodynamic properties). Metallurgical engineering reties on basic chemical engineering science, material and energy balances, and heat and mass transport. Metallurgical systems, however, are often complex. Scale-up from the bench to the commercial plant is more difficult than for other chemical processes. 

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