Leaching Shanks process

Since the 1960s the commercial development of continuous countercurrent processes has been almost entirely accompHshed by using a flow scheme that simulates the continuous countercurrent flow of adsorbent and process Hquid without the actual movement of the adsorbent. The idea of a simulated moving bed (SMB) can be traced back to the Shanks system for leaching soda ash (58). 

Guggenheim A process for extracting sodium nitrate from caliche, a native sodium nitrate found in Chile. The ore is leached at 40°C with water containing controlled concentrations of magnesium and calcium sulfates. Operated on a large scale in Chile. See also Shanks. 

Shanks An obsolete process for extracting sodium nitrate from caliche, a Chilean mineral. The ore was leached with sodium chloride solution at 70°C and the sodium chloride and nitrate were separated by fractional crystallization. See also Guggenheim. 

Leaching and washing of the leached solute from the percolation tanks by the crosscurrent methods described above will inevitably result in weak solutions of the solute. The strongest solution will result if a countercurrent scheme is used, wherein the final withdrawn solution is taken from contact with the freshest solid and the fresh solvent is added to solid from which most of the solute has already been leached or washed. In order to avoid moving the solids physically from tank to tank in such a process, the arrangement of Fig. 13.2, shown schematically for a system of six tanks, is used. This Shanks. sy5/em,t as it is called, is operated in the following manner ... 

---