Process and Apparatus for Recovering Valuable or Harmful Non-Aqueous Liquids from Slurries
AssigneePrime Services Trustee Limited
InventorCRAIG NAZZER
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Abstract
This invention relates generally to a process and an apparatus therefor for recovering valuable or harmful non-aqueous process liquids from mixtures or slurries that contain such liquids and solid particles. In a first aspect there is provided a filtration process for recovering a substantially non-aqueous process liquid from a feed slurry that predominantly comprises a mixture of the process liquid and solid particles, the process employing a sweep liquid that is less dense than the process liquid.
Claims17
A filtration process for recovering a substantially non-aqueous process liquid from a feed slurry that predominantly comprises a mixture of the process liquid and solid particles, the process employing a sweep liquid that is less dense than the process liquid and including the steps of:
- (a) introducing the feed slurry into a reservoir above a substantially horizontal filter medium therein and wherein the filter medium is adapted and dimensioned to allow liquids to flow through it in use while blocking the passage of most or all of the solid particles in the feed slurry through the filter medium;
- and
- (b) introducing the sweep liquid into the reservoir above the filter medium in such a manner so as to create a layer of the process liquid between the less dense sweep liquid above and the filter medium below, thereby creating a horizontal interface zone between the sweep liquid layer and the process liquid layer;
- and
- (c) pressurising the liquid layers above the filter medium to a pressure that is higher than the a pressure acting beneath the filter medium, such that the difference between the two pressures is sufficient to cause liquid to flow through the filter medium, thereby drawing the interface zone between the sweep liquid layer and the process liquid layer towards the filter medium;
- and
- (d) agitating by an agitation means a portion of the liquid that is in close proximity to and above the filter medium so as to impede or prevent the excessive accumulation of solid particles on the filter medium, wherein the agitation means is adapted and dimensioned to avoid excessive mixing of the sweep liquid and the process liquid;
- and
- (e) allowing the flow of liquid through the filter medium in step (c) and the operation of the agitation means in step (d) to continue until a portion of the process liquid has been displaced out of the slurry through the filter medium thereby forming a depleted slurry above the filter medium.
A filtration apparatus that is suitable for recovering process liquid from a feed slurry that predominantly comprises a mixture of the process liquid and solid particles, the apparatus including:
- (a) a reservoir suitable for holding the process liquid, a sweep liquid and feed slurry and operating at required pressures, and;
- (b) a substantially horizontal filter medium mounted in the reservoir so as to create within the reservoir an upper chamber bounded on its lower side by the filter medium and a lower chamber bounded on its upper side by the filter medium, wherein the filter medium blocks the passage of most or all of the solid particles in the feed slurry from the upper chamber to the lower chamber but allows liquids to flow through it from the upper chamber to the lower chamber, and;
- (c) a feed slurry inlet means through which feed slurry enters the upper chamber, and;
- (d) a sweep liquid inlet means through which the sweep liquid enters the upper chamber, and;
- (e) a filtrate outlet means through which filtrate flows from the lower chamber out of the reservoir, and;
- (f) a slurry outlet means through which slurry flows from the upper chamber out of the reservoir, and;
- (g) pressure connections and sources of pressure and/or vacuum connected thereto such that in use the pressure in the upper chamber is sufficiently higher than that in the lower chamber so as to cause liquid to flow downwards through the filter medium, and;
- (h) an agitator means that agitates a portion of the liquid that is in close proximity to and above the filter medium so as to impede or prevent the excessive accumulation of solid particles on the filter medium, wherein the agitation means is adapted and dimensioned to avoid excessive mixing of the sweep liquid and the process liquid.
An apparatus for recovering one or more non-aqueous process liquids from a feed slurry that comprises one or more non-aqueous process liquids and solid particles;
- the apparatus comprising:
- a) a reservoir which is adapted to accept and hold a sweep liquid and feed slurry, wherein the sweep liquid is less dense than and substantially miscible with the process liquid, wherein the feed slurry comprises a mixture of the process liquid and solid particles, and;
- b) a substantially horizontal filter medium within the reservoir which is adapted and dimensioned to allow liquids to flow through it in use while blocking the passage of most or all of the solid particles in the feed slurry through the filter medium, and;
- c) a pressurising means which is adapted to provide a pressure difference across the filter medium where a pressure above the filter medium is higher than a pressure acting beneath the filter medium, the pressure difference being sufficient to cause the liquid to flow through the filter medium, thereby drawing an interface region between the sweep liquid layer and the process liquid layer towards the filter medium when the apparatus is in use, and;
- d) an agitation means which is adapted to agitate a portion of the liquid that is in close proximity to and above the filter medium so as to impede or prevent excessive accumulation of solid particles on the filter medium, wherein the agitation means is adapted and dimensioned to avoid excessive mixing of the sweep liquid and the process liquid, and;
- e) a first outlet means adapted to allow liquid filtrate to exit the reservoir.
Dependencies are inferred from the claim text.