Concentration ratio, mineral separation

An estimate of the applicability of gravity concentration to the separation of a mineral pair of differing specific gravity can be obtained by making use of what is called the concentration criterion, which makes use of the ratio (p, - p2)/(p3 - p2), where pj is the specific gravity of the heavy mineral, p3 is the specific gravity of the light mineral, and p2 is the... 

Sorption coefficients quantitatively describe the extent to which an organic chemical is distributed at equilibrium between an environmental solid (i.e., soil, sediment, suspended sediment, wastewater solids) and the aqueous phase it is in contact with. Sorption coefficients depend on (1) the variety of interactions occurring between the solute and the solid and aqueous phases and (2) the effects of environmental and/or experimental variables such as organic matter quantity and type, clay mineral content and type, clay to organic matter ratio, particle size distribution and surface area of the sorbent, pH, ionic strength, suspended particulates or colloidal material, temperature, dissolved organic matter (DOM) concentration, solute and solid concentrations, and phase separation technique. 

The discovery of Pu has been described in detail by Seaborg in his Plutonium Story (chapter 1 of the book The Transuranium Elements 1958). First, the separation of Pu from Th caused some difficulties, because both elements were in the oxidation state 4-4. After oxidation of Pu(IV) by persulfate to Pu(VI), separation became possible. Pu is produced in appreciable amounts in nuclear reactors (section 14.1), but it has not immediately been detected, due to its low specific activity caused by its long half-life. After the discovery of Pu, plutonium gained great practical importance, because of the high fission cross section of Pu by thermal neutrons. Very small amounts of Pu are present in uranium ores, due to (n, y) reaction of neutrons from cosmic radiation with The ratio Pu/ U is of the order of 10 In 1971, the longest-lived isotope of plutonium, Pu (ri/2 = 8.00 lO y) was found by Hoffman in the Ce-rich rare-earth mineral bastnaesite, in concentrations of the order of 10 gAg-... 

Differentiation of terrestrial planets includes separation of a metallic core and possible later fractionation of mineral phases within either a solid or molten mantle (Figure 1). Lithophile and siderophile elements can be used to understand these two different physical processes, and ascertain whether they operated in the early Earth. The distribution of elements in planets can be understood by measuring the partition coefficient, D (ratio of concentrations of an element in different phases (minerals, metals, or melts)). 

Fuller et al. (1993) measured desorption rates for As(V) from ferrihydrite, aged for 24 h, as a result of increasing pH. Arsenate was first equilibrated with ferrihydrite for 144 h at pH 8.0 The molar ratio of As(V) adsorbed to Fe in ferrihydrite was 0.10 (Fig. 7). Desorption was initiated by rapidly increasing the pH to 9.0. Within a few hours, the molar ratio of As(V)/Fe had decreased to about 0.08. The rate of desorption then slowed as the rate became limited by diffusion of As(V) from pores within mineral aggregates. Within 96 h, the concentration of As(V) still adsorbed was only about 5% greater than the adsorbed concentration of As(V) determined in a separate adsorption experiment at pH 9.0. Similar desorption behavior for As(V) from ferrihydrite were measured by Fuller and Davis (1989). 

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