Patent ID: 8877065

Claim:
A skim tank, comprising: a container comprising a flow-control structure disposed within the container, wherein the flow-control structure is configured to force flow of a first portion of a solid-depleted phase of a mixed-phase feed into a toroidal motion within the container and around the flow control structure; wherein the container is configured to allow withdrawal of a second portion of the solid-depleted phase at a position below the flow control structure; a fluid conduit coupled to the container and configured to allow recycling of at least some of the second portion of the solid-depleted phase from a lower portion of the container back into the flow-control structure; an overflow element having conical shape and arranged in the container and configured to allow removal of a floating solid-enriched phase separated from the mixed-phase; one or more control elements and a plurality of vertically spaced effluent valves that are configured to force at least some of the floating solid-enriched phase into the overflow element and to remove at least some of the solid-depleted phase from the container; and wherein the overflow element has a size and position relative to the flow-control structure to (a) redirect up-flow motion of the solid-depleted phase into a side-flow motion to thereby assist in formation of the toroidal motion, and (b) to present an upper edge into the solid-enriched phase to thereby act as a weir across which the solid phase is moved.