Solvent extraction method and solvent extraction settler

Abstract

A solvent extraction method for hydrometallurgical liquid-liquid extraction processes, in which method solution phases are separated from a dispersion while the dispersion flows horizontally in a settler from a feed end to a discharge end. The mass flow of the dispersion and solution phases is divided into a plurality of parallel and mutually separated plug flows flowing in the settler from the feed end to the discharge end. The settler (1) comprises a plurality of elongated settler sections (4) which are mutually separated and side by side in parallel to each other, Inc settler sections (4) extending from the feed end (2) to the discharge end (3), forming a plurality of mutually separated parallel plug flow channels.

Claims

1. A solvent extraction method for hydrometallurgical liquid-liquid extraction processes, in which method solution phases are separated from a dispersion while the dispersion flows horizontally in a settler from a feed end to a discharge end, characterized in that the mass flow of the dispersion and solution phases is divided into a plurality of parallel and mutually separated plug flows flowing in the settler from the feed end to the discharge end, the settler including two consecutively interconnected first and second settler elements, the first settler element having at least one coalescing member to coalesce the dispersion into different phases and the second settler element comprising a retention module to increase residence time of the dispersion in the settler.

2. A solvent extraction settler configured to perform hydrometallurgical liquid-liquid extraction processes, the settler having a feed end and a discharge end, said settler being arranged to separate solution phases from a dispersion while the dispersion flows horizontally from the feed end towards the discharge end, characterized in that the settler comprises a plurality of elongated settler sections which are mutually separated and side by side in parallel to each other, the settler sections extending from the feed end to the discharge end, forming a plurality of mutually separated parallel plug flow channels, the settler including two consecutively interconnected first and second settler elements, the first settler element having at least one coalescing member to coalesce the dispersion into different chases and the second settler element comprising a retention module to increase residence time of the dispersion in the settler.

3. The settler according to claim 2, where the settler comprises a plurality of feed inlets, and where one feed inlet is arranged to feed dispersion individually to each settler section.

4. The settler according to claim 2, where the settler sections are formed of tubular shells.

5. The settler according to claim 2, where the settler comprises a bottom, a vertical feed end wall at the feed end, a vertical discharge end wall at the discharge end, and vertical side walls extending between the ends of the feed end wall and the discharge end wall, together forming a rectangular tank having an inner space; and where a plurality of partitions are arranged in parallel in the tank at a distance from each other to extend between the feed end wall and the discharge end wall so that the inner space is divided by said partitions into the settler sections.

6. The settler according to claim 5, where the partitions are rigid structures.

7. The settler according to claim 5, where the partitions are flexible.

8. The settler according to claim 2, where the settler comprises a plurality of separate chutes arranged side by side in parallel to each other, said chutes forming said settler sections, each chute comprising a bottom and vertical side walls.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

(2) FIG. 1 is an axonometric view of a solvent extraction settler according to a first embodiment of the present invention,

(3) FIG. 2 shows a section II-II from FIG. 1,

(4) FIG. 3 is an axonometric view of a solvent extraction settler according to a second embodiment of the present invention,

(5) FIG. 4 shows a section IV-IV from FIG. 3,

(6) FIG. 5 is an axonometric view of a solvent extraction settler according to a third embodiment of the present invention,

(7) FIG. 6 a section VI-VI from FIG. 5,

(8) FIG. 7 is an axonometric view of a solvent extraction settler according to a fourth embodiment of the present invention,

(9) FIG. 8 is a section VIII-VIII from FIG. 7,

(10) FIG. 9 is an axonometric view of a solvent extraction settler according to a fifth embodiment of the present invention, and

(11) FIG. 10 is a section X-X from FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

(12) FIGS. 1 to 10 show different embodiments of a solvent extraction settler 1 to be used in hydrometallurgical liquid-liquid extraction processes for separating solutions which have been mixed in a dispersion into different solution phases. The figures show only the settler 1. The mixing unit which prepares the dispersion, the feeding device which feeds the dispersion to the settler and the discharge launders which discharge the separated solution phases are not shown in the Figures because they are not the object of this invention.

(13) In each embodiment of FIGS. 1 to 10 the settler 1 comprises a plurality of elongated settler sections 4 which are mutually separated and arranged side by side 30 in parallel to each other. The settler sections 4 extend from the feed end 2 of the settler to the discharge end 3 of the settler. The settler sections 4 form a plurality of mutually separated parallel plug flow channels. In operation, the dispersion and solutions form a plug flow pattern in these plug flow channels. The settler 1 comprises a plurality of feed inlets 5 at the feed end 2 of the settler 1. Each feed inlet 5 feeds dispersion to a specific single settler section 4. By dividing the flow into several sub-flows which flow in separate settler sections 4, a large specific surface area is created which enhances coalescence in the dispersion.

(14) In the embodiments of FIGS. 1, 2 and 3, 4 the settler sections 4 are formed of tubular shells S. Tubular shells S can be made gas-tight. The gas-tight closed compartments of the tubular shells provide fire protection against accidental fires. Mist emissions cannot escape from the atmosphere in the interior of the gas-tight shells to the outer atmosphere to contaminate the air and worsen the working conditions. Likewise, the surrounding air and e.g. insects and birds cannot enter the shells. In addition, when the lighter solution is an organic phase, the oxidation degree of the organic phase decreases, whereby solution costs are reduced.

(15) FIGS. 1 and 2 show a settler 1 having eight settler sections 4 arranged side by side in parallel to each other. Each settler section 4 is formed of the tubular shells S of two self-supporting settler element modules A and B which are consecutively interconnected. The first settler element module A is a coalescing module having one or more coalescing fence elements to coalesce the dispersion into different solution phases. The second settler element module B is a retention module to increase residence time in the settler for enhancing the phase separation.

(16) Each of the settler element modules A, B has exterior dimensions, strength and handling and securing means which conform to shipping container standards to enable shipping standard compatible transportability. In particular, each settler element module A, B comprises a self-supporting framework structure 15 having a shape of a rectangular parallelepiped with exterior dimensions and corner fittings 16 conforming to shipping container standards. The corner fittings 16 are attached to each eight corners of the framework structure 15. Preferably, each module A, B conforms to standard ISO 668 Series 1 Freight containersClassification, dimensions and ratings. The corner fittings 16 conform to standard ISO 1161 Series 1 Freight containersCorner fittingsspecification.

(17) The tubular shells S are preferably made of a fibre-reinforced plastic composite and are supported inside the framework structure 15. Preferably the tubular shell S is made by filament winding technology. The inner surface of the shell S, which in operation comes to contact with the dispersion and solvents, is inherently smooth because when manufactured by filament winding it is formed against a mandrel which has a smooth surface. The smooth surface contacting the solvent flow minimizes local turbulences and enhances phase coalescence. The smooth surface also minimizes electrostatic charging and thereby reduces the risk for fires due to igniting of volatile organic compounds in the inner atmosphere of the shell caused by electrostatic discharge. Electrostatic charging can also be reduced by adding carbon staple fibers to the plastic composite.

(18) As can be seen in FIG. 2, the tubular shells S of the coalescing module A and the retention module B have a substantially rectangular cross-sectional shape with cambered corners and convexly outwards curved side walls. The cross-section of the shells S of the coalescing module A is equal to the cross section of the shells S of the retention module B to enable abutting joint of the shells S.

(19) FIGS. 3 and 4 show an embodiment of the settler 1 which has seven elongated settler sections 4 which are mutually separated and side by side in parallel to each other. The settler sections 4 extend from the feed end 2 to the discharge end 3 and form seven mutually separated parallel plug flow channels. The settler sections 4 are formed of tubular shells S having a circular cross-section.

(20) FIGS. 5, 6 and 7, 8 show two embodiments of settlers 1 which both comprise a bottom 6, a vertical feed end wall 7 at the feed end 2, a vertical discharge end wall 8 at the discharge end 3, and vertical side walls 9, 10 extending between the ends of the feed end wall and the discharge end wall. The bottom 6 and walls 7, 8, 9, 10 form a rectangular tank having an inner space. Seven partitions 11 are arranged in parallel in the tank at a distance from each other to extend between the feed end wall 7 and the discharge end wall 8 so that the inner space is divided by said partitions into eight settler sections 4.

(21) In the settler 1 of FIGS. 5 and 6 the partitions 11 are rigid structures, such as midwalls made of a plastic composite, metal or any other suitable rigid material.

(22) In the settler 1 of FIGS. 7 and 8 the partitions 11 are made of a flexible material, such as tarp fabric, and act as flow guides in the tank to form said mutually separated plug flow channels.

(23) FIGS. 9 and 10 show a settler 1 which comprises a plurality of separate chutes 4 or launders arranged side by side and in parallel to each other. The chutes form the settler sections 4. Each chute 4 comprises a bottom 12 and vertical side walls 13, 14.

(24) It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead, they may vary within the scope of the claims.