The present invention relates to a solvent extraction plant comprising a foundation.

BACKGROUND OF THE INVENTION

As taught in the article "Solvent Extraction Mixer- Settler Design", by M.L. Jansen and A. Taylor, ALTA Metallurgical Services Publication. Jansen, M. L., Taylor, A, 1997, a typical arrangement of a mixer- settler consists of an agitated tank (mixer or mix box) in which the aqueous and organic solutions are contacted, followed by a shallow gravity settling ba- sin (settler) where the solutions disengage into indi ^¬ vidual layers for separate discharge. The settler may be cylindrical or rectangular, though a rectangular shape is most commonly used in order to provide a more compact layout, and to minimize interstage piping runs.

The settler tank is normally built on the site, WO 2007/135221 Al discloses one method for manufacturing a mixer-settler on site. The wall structures are con- nected by vertical support columns to the bottom plate. The wall structure is formed by fastening a re ^¬ quired number of horizontal support beams to the ver ^¬ tical support columns at regular intervals. A required number of plate-like wall elements made of a chemical- ly resistant material are attached to the horizontal support beams inside the mixer-settler, so that they form a load-bearing structure in the spaces left be ^¬ tween the horizontal support beams. The plate-like wall elements are connected to the plate-like element covering the bottom plate of the mixer-settler. Such a settler is still a large tank which is square in plan and its square area is about several hundred square meters .

In the above-mentioned article "Solvent Extraction Mixer-Settler Design", by M.L. Jansen and A. Taylor, ALTA Metallurgical Services Publication. Jansen, M. L., Taylor, A, 1997, there is further disclosed three alternative concepts of foundation or support for the settler. In the first one, the settlers are at the ground level. The other two concepts involve the ele ^¬ vation of the settlers on fill or concrete, steel or wooden supports, and are more applicable to flat sites. The problem in all these concepts is that they do not allow unobstructed access below the settler. Further, a lot of excavation and construction work must be made at the site which causes problems because of the crucial influence of local factors. It may be difficult to get local suppliers. The quality of the site work may vary. The solvent extraction plant is project specified. In each case the layout of the plant and the equipment are unique. Further, there is not a possibility for productization of the settlers.

OBJECT OF THE INVENTION

The object of the invention is to eliminate the disad ^¬ vantages mentioned above.

SUMMARY OF THE INVENTION

The invention provides a solvent extraction settler comprising a foundation. The solvent extraction settler comprises self-supporting modules each having exterior dimensions, strength and corner fittings conforming to shipping container standards. The foundation comprises a plurality of pillars on which the modules are supported at a height above the ground level, thereby providing a space for piping and access below the plant, and the pillars comprise shipping standard compatible container lashing fittings to which the corner fittings of the modules can be con ^¬ nected .

The advantage of the fact that the settler modules and also the pillars (with or without cast concrete) can be manufactured in the factory environment, which is different from the installation site environment, is that it provides good quality. The settler modules be ^¬ ing ISO shipping container standard compatible units provides all benefits of the normal shipping contain ^¬ ers: they can be handled with normal transport equip ^¬ ment and there is no need for oversize transport equipment. The settler element modules having the di ^¬ mensions, strength and handling and securing means conforming to shipping container standards thus have all the benefits of the transportability of normal shipping containers. The settler modules can be trans- ported on land by trucks and trailers and on container ships by sea. In ports they can be handled with normal container handling equipment. A complete solvent ex ^¬ traction plant, which may comprise one or more set ^¬ tlers, can be shipped in one delivery. The modules have the strength and durability to withstand stacking of a number of modules on top of one another. Concrete pillars which are arranged to support each corner of the modules allow flexible level positioning of the settler and enable construction of the entire solvent extraction plant on the planar ground. Pillars also enable access below the settler, and piping for the water circulation can also be arranged below the settler. A minimal amount of excavation work is required at the installation site, speeding up the installa- tion. The project lead time is short. Mounting of the modules on pillars allows easy assembly and disassem ^¬ bly of the modules and settler. The modular system al- lows flexible capacity since more capacity can be built while the plant is running simply by adding more pillars and modules onto said pillars. In one embodiment of the settler, the pillar comprises a lower end which is supported on the ground, an upper end, and one or more container lashing fittings at ^¬ tached to the upper end of the pillar. In one embodiment of the settler, the container lashing fitting comprises a stacking cone.

In one embodiment of the settler, the container lashing fitting comprises a twist lock.

In one embodiment of the settler, the pillar comprises one to four container lashing fittings, depending on the number of corner fittings to be connected onto the pillar .

In one embodiment of the settler, the pillar comprises a plastic tube, a concrete reinforcement arranged in ^¬ side the plastic tube, cast concrete cast inside the plastic tube, and a metal base plate attached to the upper end of the pillar, to which base plate one or more container lashing fittings are fixedly connected.

In one embodiment of the settler, the modules and their corner fittings conform to ISO shipping contain- er standards. The container lashing fittings on the pillars are ISO shipping standard compatible.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to pro- vide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the de- scription help to explain the principles of the inven ^¬ tion. In the drawings:

Figure 1 is an axonometric view of a solvent extrac- tion settler according to a first embodiment of the present invention,

Figure 2 is a view of the layout of the foundation of the settler of Figure 1,

Figures 3 to 6 show an axonometric view of four dif ^¬ ferent types of pillars used in the foundation of Fig ^¬ ure 2, the pillars being equipped with stacking cones as container lashing fittings,

Figures 7 and 8 show another embodiment of the pillar equipped with a twist lock as a container lashing fitting, and Figure 9 shows a schematic longitudinal section of the pillar .

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows one embodiment of a solvent extraction settler 1 which is used in hydrometallurgical liquid- liquid extraction processes for separating solutions mixed in a dispersion into different solution phases. The dispersion pump and mixers which are used to pre ^¬ pare the dispersion are not shown in the Figures. The settler 1 comprises a plurality of self-supporting modules 3. Each of the modules 3 has the exterior di ^¬ mensions, strength and handling and securing means, i.e. corner fittings 4, which conform to ISO shipping container standards to enable ISO compatible trans- portability. In particular, each module 3 comprises a self-supporting framework structure having a shape of a rectangular parallelepiped with exterior dimensions and corner fittings 4 conforming to ISO shipping container standards. The corner fittings 4 are attached to each eight corners of the framework structure. Each module 3 conforms to the standard ISO 668 Series 1 "Freight containers - Classification, dimensions and ratings". The corner fittings 4 conform to the stand ^¬ ard ISO 1161 Series 1 "Freight containers - Corner fittings - specification". Figure 2 shows a layout of the foundation 2 designed for the module group of the settler shown in Figure 1. The settler 1 comprises a foundation 2 on which the modules 3 are supported at a height above the ground level, thereby providing a space for piping and access underneath the settler 1. The foundation 2 comprises a plurality of pillars 5 having ISO shipping standard compatible container lashing fittings 6, 7 to which the corner fittings 4 of the modules 3 can be connect ^¬ ed .

Figures 3 and 9 show that the pillar 5 comprises a low ^¬ er end 8 which is supported on the ground, and an upper end 9. One or more container lashing fittings 6, 7 are attached to the upper end 9. As illustrated in Figures 3 to 6, the pillar 5 may comprise one to four container lashing fittings 6, 7, depending on the number of corner fittings 4 to be connected onto the pillar 5. A pillar 5 supporting one corner of the module comprises only one container lashing fitting 6 (Fig. 3) . A pillar 5 supporting two corners of parallel modules comprises a pair of container lashing fittings 6 arranged side- by-side (Fig. 4) . A pillar 5 supporting two corners of sequential modules comprises a pair of container lash ^¬ ing fittings 6 arranged in a row (Fig. 5) . A pillar 5 supporting four corners of parallel and sequential mod ^¬ ules comprises two pairs of container lashing fittings 6 (Fig. 6) . The container lashing fittings may be stacking cones 6 as shown in Figures 3 to 6 or alterna ^¬ tively they may be twist locks 7 as shown in Figures 7 and 8. With reference to Figure 9, the pillar 5 comprises a plastic tube 10, a concrete reinforcement 11 of metal arranged inside the plastic tube 10, cast concrete 12 cast inside the plastic tube 10, and a metal base plate 13 attached at the upper end 9 of the pillar, to which base plate 13 one or more container lashing fittings 6, 7 are fixedly connected.

The solvent extraction settler 1 is manufactured so that at the site of manufacture, such as in an engi- neering workshop, a plurality of self-supporting mod ^¬ ules 3 is manufactured. Each module 3 has the exterior dimensions, strength and handling and securing means 4 conforming to ISO shipping container standards. The modules 3 are transported to the site of installation as normal freight by transport equipment, such as trucks, trailers and container ships, capable of han ^¬ dling and transporting ISO compatible units. At the site of installation, pillars 5 are supported on the ground in a configuration according to the layout of the intended settler. Finally, at the site of instal ^¬ lation, the modules 3 are assembled into a complete settler 1 built of pillars 5, and the corner fittings 4 of the modules 3 are engaged to the container lash ^¬ ing fittings 6, 7 of the pillars 5.

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 in ^¬ vention and its embodiments are thus not limited to the examples described above; instead, they may vary within the scope of the claims.