Solid-fluid contacting apparatus

A system for contacting solid particles with at least two batches of liquid without removing solid particles contained therein comprising, in combination:

• an enclosed vessel adapted for holding liquids and solid particles within said vessel;
• a conduit extending through the top of said vessel and terminating near the bottom of said vessel below the level of the liquid in said vessel when a reaction is progressing within said vessel;
• a first means connected externally of the vessel to said conduit for introducing a liquid into the vessel through said conduit;
• a second means connected externally of the vessel to said conduit for withdrawing through said conduit the liquid that has been contacted with solid particles;
• filtering means within said conduit for preventing solid particles carried by the liquid from being withdrawn from the vessel, solid particles that are retained by, or embedded in, the filter means when liquid is withdrawn being dislodged therefrom and carried back into the contacting zone of the vessel by the subsequent batch of liquid introduced by the first means;
• a second conduit having no filtering means and extending through the top of the vessel and terminating near the bottom of the vessel in order to charge or remove the solid particles therethrough;
• a mechanical stirrer extending through the top of the vessel and to such a point near the bottom of the vessel that the liquid may be stirred in order to improve the contact between the liquid and the solid particles;
• and
• a passageway extending through the sidewall and above the level of the liquid in said vessel with means to add pressurizing gas to the vessel.