Method for recovering liquids from slurries

A method for separating Process Liquid from a feed slurry that comprises a mixture of the Process Liquid and solid particles by use of a Sweep Liquid that has a higher density than the Process Liquid, the method comprising:

• (a) introducing the feed slurry into a reservoir thereby creating or enlarging a Process Liquid Layer, said reservoir comprising a Filtering Device having an upstream surface and comprising one or more filter elements allowing liquid to flow through it while blocking the passage of at least a portion of said solid particles, where (a) can occur before, after or at the same time as (b);
• (b) introducing the Sweep Liquid into the reservoir thereby creating or enlarging a Sweep Liquid Layer below the Process Liquid Layer and an interface between the two liquid layers that lies below at least a portion of the upstream surface of the Filtering Device, where (b) can occur before, after or at the same time as (c);
• (c) continuing to introduce feed slurry and/or Process Liquid and/or Sweep Liquid into the reservoir causing the top of the Process Liquid Layer to rise and make contact with the upstream surface of the Filtering Device;
• (d) applying a pressure differential across at least one or more of the filter elements within the Filtering Device, wherein said pressure differential is sufficient to cause liquid to flow through the Filtering Device as filtrate thereby causing Process Liquid to flow through the Filtering Device;
• (e) operating one or more Solids Accumulation Prevention Means (“SAP Means”) that are configured to prevent excessive accumulation of solid matter on or within the upstream surface of the Filtering Device;
• (f) allowing solid particles in the Process Liquid Layer to move out of the Process Liquid Layer and into the Sweep Liquid Layer thereby separating Process Liquid from solid particles;
• (g) raising the level of the top of the Sweep Liquid Layer within the reservoir thereby exerting upward pressure against the Process Liquid Layer thereby causing Process Liquid to flow through the Filtering Device thereby separating Process Liquid from solid particles that are blocked by the Filtering Device, and;
• (h) allowing solid particles that have been separated from Process Liquid by steps (f) and (g) to accumulate in the Sweep Liquid Layer, thereby forming a mixture comprising solid particles and Sweep Liquid in the reservoir.