Leaching Pachuca tanks

The pulp-water systems encountered in the agitation of paper stock represent a highly specialized case of solid-liquid agitation, discussed in a few papers (CIO, K5, 04), which will not be reviewed here. Lamont (L2) discusses the operation of pachuca tanks, used for ore-leaching operations, in which agitation results from air introduced at the tank bottom. 

Finely divided solids can be suspended in leaching solvents by agitation, and for batch operation a variety of agitated vessels are used (see Chaps. 6 and 11). The simplest is the Pachuca tank (Fig. 13.5), which is employed extensively... 

The leaching is 50—60°C without external heating. The cone-bottom tanks are equipped with a pipe from just above the solution level to near the bottom through which air is blown forming bubbles which lower the density of the slurry. These leach tanks, caHed Pachucas, are fairly efficient and are stiH popular although many plants employ mechanical agitators. Most plants use 3—5 tanks in series with acid and calcine being fed to the first and, in some cases, downstream from the first tank as weH. 

Fig, 2.3. Pachuca leaching tanks at Western Reefs Uranium Plant, South Africa (Arden, T.V. Ref. 1). 

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