Liquor pressure equation

The recovery of uranium from the leach liquor is effected either by acidification to about pH 6 to liberate C02 or, more usually, by addition of hydroxide to precipitate diuranate, as shown in equation (27). In this latter case the pH is maintained at about 11. The species present in 0.055 M UVI solutions, acidified to pH 4.56 under 1 bar C02 pressure, have been summarized73 in a study of the reactive ion exchange adsorption of uranyl nitrate on to a bicarbonate loaded anion... 

The enthalpy of the vapor with respect to the thick liquor now represents the latent heat of vaporization at the operating pressure in the evaporator. Equation (18) then yields... 

For constant-pressure filtration and washing, such as occur on vacuum filters, the filtration time and washing time can be related through the wash ratio if the wash liquor and filtrate are assumed to have similar physical properties. From the equation for incompressible filtration at constant pressure expressed in terms of a, ecffic resistance ... 

Consider now compaction in the centrifuge. In the decanter centrifuge the geometry is quite different, as illustrated in Figure 4.13. Nevertheless, the equivalent pressure heads may be derived using equation (4.61) for pressure. Pr, developed at radius r within a centrifuge. In equation (4.61) an expression is given for the pressure developed at radius r with liquor above to a level of radius rj. In the present case, it is required to know the pressure of the head of cake, at the bowl wall radius, r2, with the surface of the cake at radius, ri. Thus, meeds to be replaced by r2, and ri by r in equation (4.61). 

To model the flow behaviour of free liquor (liquor within the tube), the Navier-Stokes equation is employed to describe the flow velocity and pressure distributions within the tube of the package (see Fig. 4.5). 

The pressure distribution across the cross-section of the tube and yarn assembly (see Plate I, line y=0), under different liquor inflow rates, where the flow in porous media is described by Brinkman s equation. 

Darcy s law and by the Brinkman equation, respectively. It can be seen that, in both approaches, the pressure profiles within the free liquor (tube) are quite stable and almost constant under the different inflow rates the pressure profiles within the porous package decrease almost linearly at the different inflow rates. 

The flow velocity distributions within the porous yam assembly are dominated by the pressme rather than the flow velocity distributions within the free liquor circulating in the spindle. This result is obtained using Brinkman equations. It further proves the validity of Darcy s law in characterising the flow within the porous medium, since it agrees with Darcy s assumption that the only driving force for flow in a porous medium is the pressure gradient. 

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