High advantages, disadvantages

Hydrometallurgical methods can be applied when low-grade oxidized (oxide) or mixed (oxidized and sulphidic) ores are available. These methods have advantages of high selectivity disadvantages are the relative slowness of leaching and the large volume of solution per unit mass of copper. 

Advantages are no loss of material, no dimensional restrictions, and high capacity. Disadvantages are longer heating times, less purification, lower efficiency of heating, and higher maintenance costs. 

These disadvantages have recently been alleviated by the introduction of a method to prepare liposomes from microemulsions formed by a combination of Sl with a hydrotrope (H) [47]. The hydrotropes are short-chain molecules, usually with an ionic group [48,49]. The combination is highly advantageous as a precursor to the preparation of liposomes, as demonstrated in Fig. 4, which illustrates the pronounced difference from micellarly solubilized species as precursors (Fig. 2). The Sm/Sl ratio is typically approximately 2, and the H/Sl ratio is on the order of 0.25, which is one order of magnitude improvement. In addition, it should be realized that the surface activity of the hydrotrope molecule is far less than that of the surfactant, which is another advantage. 

Other Resins. Many other resins have been processed by rotational molding. In most cases their disadvantages outweigh their advantages. Disadvantages include high cost, poor impact strength, and low flowabiUty (Table 3). 

Dense ceramic membranes allow oxygen or hydrogen permeation in a dissociated or ionized form other than the conventional molecular diffusion, and thus exhibit extremely high selectivity (up to 100%). They can be incorporated into membrane reactors for a variety of oxidation and dehydrogenation reactions where the membrane functions as either a product extractor or a reactant distributor. Three configurations, that is, disc/flat-sheet, tubular and hollow fibre membranes have been applied in membrane reactors. They exhibit respective advantages/disadvantages in terms of the ease and cost of fabrication, the effective membrane area/volume ratio, and... 

Figure 9.18 provides an overview of the application envelope and the respective advantages and disadvantages of the various artificial lift techniques. As can be seen, only a few methods are suited for high rate environments gas lift, ESP s, and hydraulic systems. Beam pumps are generally unsuited to offshore applications because of the bulk of the required surface equipment. Whereas the vast majority of the world s artificially lifted strings are beam pumped, the majority of these are stripper wells producing less than 10 bpd. 

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