BACKGROUND OF THE INVENTION

1. TECHNICAL FIELD

[0001] The present invention relates to the field of mineral production, ore extraction and mineral rinsing involving waste water desalination, and more particularly, to underwater mineral sorting, mineral dressing and mineral rinsing.

2. DISCUSSION OF RELATED ART

[0002] Mineral production requires sorting the mineral ores from the rock material in which they are embedded. When producing minerals underwater, it is not efficient to deliver all the material to the shore for processing, as most material is not needed and creates environmental problems.

[0003] Mineral dressing is the extraction and processing of mineral ores from the rock material in which they are embedded. Underwater mineral dressing is much more difficult than mineral dressing on land or in mines, as the minerals are usually associates with huge amounts of unneeded rock material.

[0004] Freeze desalination is a known desalination method which presents however technical difficulties in implementation, mainly due to accumulation of ice that results in a reduced thermal contact and mechanical ice removal challenges.

SUMMARY OF THE INVENTION

[0005] One aspect of the present invention provides systems and methods for sorting crushed material by gravitationally separating components of the crushed material according to component densities in a liquid column comprising at least a bottom layer of a heavy water-immiscible liquid, an intermediate layer of an aqueous salt solution and a top layer of a light water-immiscible liquid. The heavy water-immiscible liquid is selected to have a higher density than the aqueous salt solution, the aqueous salt solution is selected to have a higher density than the light water- immiscible liquid and the light water-immiscible liquid is selected to have a higher density than sea water to maintain the intermediate layer on top of the bottom layer, the top layer on top of the intermediate layer and the top layer in the liquid column.

[0006] One aspect of the present invention provides an underwater mineral dressing unit comprising: a vertical vessel comprising at least one pair of a flow compartment and a milling compartment, wherein the flow compartment is positioned above and in fluid communication with a milling compartment; and a water-immiscible liquid filling the vertical vessel and selected to have a density that is intermediate between lighter gangue material and heavier product material, to float the gangue material and to sink the product material, wherein the milling compartment comprises grinding rolls configured to receive material from the flow compartment into a volume between the rolls and direct the floating gangue material back to the flow compartment via lateral volumes with respect to the rolls.

[0007] One aspect of the present invention provides a desalination system comprising a vertical vessel having a bottom layer of a heavy water-immiscible liquid; a brine layer on top of the bottom layer; an intermediate layer of a light water-immiscible liquid on top of the brine layer; and a top water layer on top of the intermediate layer. A density of the heavy water-immiscible liquid is selected to be larger than a density of the brine, and a density of the light water-immiscible liquid is selected to be smaller than a density of the brine and larger than a density of the top water layer. The desalination system further comprises a brine handling unit arranged to introduce brine or a dilute salt solution into the bottom layer and remove concentrated brine from the brine layer. The desalination system is arranged to freeze water in the brine layer and enable floating of the ice from the brine layer to the top water layer.

[0008] These, additional, and/or other aspects and/or advantages of the present invention are set forth in the detailed description which follows; possibly inferable from the detailed description; and/or learnable by practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a better understanding of embodiments of the invention and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings in which like numerals designate corresponding elements or sections throughout.

[0010] In the accompanying drawings:

[0011] Figure 1 is a high level schematic block diagram of an underwater crushed material sorting unit that is part of an underwater mineral production system, according to some embodiments of the invention; and

[0012] Figure 2 is a high level schematic illustration of an underwater mineral production method, according to some embodiments of the invention.

[0013] Figure 3 is a high level schematic illustration of an underwater mineral dressing unit and system according to some embodiments of the invention; [0014] Figures 4A and 4B are high level schematic illustrations of configurations of system according to some embodiments of the invention; and

[0015] Figure 5 is a high level schematic flowchart of a method of underwater mineral dressing, according to some embodiments of the invention.

[0016] Figure 6 is a high level schematic process diagram of an exemplary desalination and rinsing system, according to some embodiments of the invention.

[0017] Figure 7 is a high level schematic illustration of processes in a desalination system, according to some embodiments of the invention.

[0018] Figure 8 is a high level schematic flowchart illustrating a desalination method according to some embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Prior to the detailed description being set forth, it may be helpful to set forth definitions of certain terms that will be used hereinafter.

[0020] The term "brine", "water" or "salt water solution" as used in this application refers to any salt water solution, dilute or concentrated. Generally, the term "brine" is used to refer to a more concentrated solution than the term "dilute salt solution", which in turn is used to refer to a more concentrated solution than the term "water". However, as the disclosed invention is flexible in its possible adjustments and application, and as the disclosed concentration processes are gradual and involve mixing of solutions of varying concentrations, these terms is to be considered as equivalent, and any use of one or the other should be understood in a non-limiting sense. Furthermore, the term "ice" as used in this application refers to any mixture of water and ice as well as to ice bodies.

[0021] The term "gradient" as used in this application refers to a monotonous change (in the weak sense) of a quantity, e.g., a step- wise change, a continuous change, ranges in which the quantity is constant and there is no change, and combinations of such conditions. In particular, the term "vertical density gradient" is to be understood to comprise any of the following: a stepwise change in density (layers of liquids having increasing densities from top to bottom), a partially continuous change in density (one or more layers having a continuously or stepwise changing density), ranges of constant density and any combination of these features. In particular, the vertical density gradient may comprise set of liquids with different densities.

[0022] With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

[0023] Before at least one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is applicable to other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0024] Figure 1 is a high level schematic block diagram of an underwater crushed material sorting unit 101 that is part of an underwater mineral production system 100, according to some embodiments of the invention.

[0025] Underwater crushed material sorting unit 101 comprises a container 115 comprising a bottom layer 140 of a heavy water-immiscible liquid, an intermediate layer 130 of an aqueous salt solution and a top layer 120 of a light water-immiscible liquid.

[0026] In certain embodiments, the heavy water-immiscible liquid is selected to have a higher density than the aqueous salt solution, the aqueous salt solution is selected to have a higher density than the light water-immiscible liquid and the light water-immiscible liquid is selected to have a higher density than sea water to maintain intermediate layer 130 on top of bottom layer 140, top layer 120 on top of intermediate layerl30 and top layer 120 within container 115.

[0027] Container 115 is arranged to receive crushed material 90A having a weight distribution.

Without wishing to be bound by theory, topping the liquid column, composed of layers 120, 130, 140, by top layer 120 which is water-immiscible and heavier than seawater prevents mixing of layer

120 with seawater, ensures than the liquid column stays undiluted and within container 115 and also removes seawater from delivered crushed material 90A.

[0028] Underwater crushed material sorting unit 101 further comprises at least one discharger (e.g., dischargers 150, 160) arranged to remove at least one respective part (e.g., 90F, 90E respectively) of the material from at least one respective layer (e.g., 140, 130 respectively). For example, unit 101 may comprise a first discharger 160 arranged to remove a first part 90E of the material (90C) from intermediate layer 130; and a second dischargerl50 arranged to remove a second part 90F of the material (90D) from bottom layer 140. [0029] Without wishing to be bound by theory, the densities of light water-immiscible liquid, aqueous salt solution and heavy water-immiscible liquid determine which parts 90B, 90C, 90D (respectively) of delivered crushed material 90A accumulate in each layer 120, 130, 140 respectively.

[0030] In certain embodiments, the liquids and solution may be selected to separate a target product and tailings into different layers in container 115. For example, is the product is heavier than tailings, the liquids and solution may be selected to accumulate the product in a different and lower level than the layer in which tailings accumulate. For example, the target product may accumulate as part 90D in bottom layer 140 while the tailings may accumulate as parts 90C and 90B and left in intermediate and top layers 130, 120 respectively in container 115.

[0031] In certain embodiments, the aqueous salt solution may comprise aqueous solutions of various mineral salts and mixtures thereof, which have a density that is sufficient for waste rock floating, for example, aqueous solution of sodium or potassium silicone-tungstate, or generally an alkali metal silicone- tungstate.

[0032] In certain embodiments, the light water-immiscible liquid has a density that is intermediate between that of the waste rock and sea water, for example, phthalic acid dibutyl ether (dibutylphthalate, density 1.05 g/cm ) or a mixture of various individual organic compounds (e.g., hexane mixture with perfluorocyclobutane). Light water-immiscible liquid may thus be used as a non-aqueous layer screening the water-salt solution from the seawater.

[0033] In certain embodiments, the heavy water-immiscible liquid has a density that exceeds the density of the aqueous salt solution. For example, the heavy water-immiscible liquid may comprise bromoform (CHBr ₃ ,a small amount of this substance is even synthesized by algae in the ocean), tetrabromoethane (C ₂ H ₂ Br ₄ ), tribromofluoromethane (CB^F), pentabromofluoroethane (C ₂ Br ₅ F) or their mixtures.

[0034] Generally, other chemically inert halogenated organic compounds with appropriate rheological, thermodynamic and hygiene and sanitary properties according to specifications may be used as either water-immiscible liquids.

[0035] In certain embodiments, underwater mineral production system 100 may comprise at least one underwater crushed material sorting unit 101, at least one underwater dredge 110 arranged to deliver crushed material 90A to at least one underwater crushed material sorting unit 101; and at least one target product container 170 arranged to receive at least one respective part 90F of delivered crushed material 90 A. In system 100, the liquids and solution may be selected to concentrate a target product in bottom layer 140 and leave tailings in intermediate and top layers 130, 120 in container 115, wherein target product container 170 is arranged to receive target product 90F

[0036] Advantageously, the present invention expands the range of processable mineral sources by enabling their gravitational differentiation from waste rock in which they are embedded, increases the process productivity, reduces power consumption and prevents removal of heavy water-salt medium out of the technological process.

[0037] In certain embodiments, system 100 is used to stratify ripped raw material deposits from the sea bottom in a water-salt medium with a density that exceeds that of sea water. The rock mass is taken from the sea bottom and delivered for stratification into a water-salt medium (layer 130) through top layer 120 of a screening water-immiscible non-aqueous liquid with the density intermediate between those of the water-salt medium and sea-water. Meanwhile, the removal of sunken material is realized through bottom layer 140 of another immiscible non-aqueous underlying liquid with a higher density.

[0038] Advantageously, isolation of the heavy water-salt medium from both below and above by layers of non-aqueous liquids immiscible with sea water protects the working water-salt medium from dilution by sea water introduced into the process with the initial raw material. Additionally, it prevents the removal of working liquid, in which the dressing process takes place, together with dressing products. The illustrated process is continuous, because it is not necessary to lift the container with water-salt medium on board of the commercial ship every time it is filled, and allows the production of minerals, whose density exceeds that of the waste rock, from the sea bottom. It ensures the production of especially valuable kinds of raw minerals with the same productivity with respect to the initial rock mass independently of the production depth and valuable component content in the ore.

Example

[0039] In a non-limiting example, rock mass delivered by underwater dredge 110 is submerged through layer 120 of water-immiscible non-aqueous liquid (in a non-limiting example, a mixture of hexane with perfluorocyclobutane density 1.05 g/cm3) into layer 130 of heavy water-salt medium (in a non-limiting example, aqueous solution of sodium silicon-tungstate, density 2.78 g/cm ³ ), where the component minerals are stratified into light (e.g., part 90B as final tailings) and heavy (e.g., part 90C as concentrated material) fractions. After the settling fraction 90C passes layer 130 of the heavy water-salt medium, the target product (e.g., part 90D) submerges further into layer 140 of water- immiscible liquid, even heavier organic liquid (in a non-limiting example, bromoform, density 2.89 g/cm3) and then is taken out of the process though a sea-water layer using screw discharger 150 as 90F. During the removal of product 90D, heavy organic liquid on the surface of the solid material may be substituted by sea- water and thus maintained within layer 140 in container 115. Similarly, the light fraction 90B representing final tailings may also be taken out of the stratification process using screw discharger 160, and then arranged in the worked-out space as 90E. Due to the high density of the salt solution in layer 130 it too stays within intermediate layer 130 and container 115 and does not mix with sea water or dilute. In other embodiments however, parts of any of the liquids and solution may be regularly refreshed or replaced .The ready product (90F in this non-limiting example) may be reloaded into target product container 170 to be delivered on board of the commercial ship.

[0040] In certain embodiments, either or all of layers 120, 130, 140 may comprise a density gradient to enhance and refine the separation efficiency of the delivered rock mass. In certain embodiments, the density of either or all of layers 120, 130, 140 may be constant.

[0041] Without wishing to be bound by theory, heavy water-salt medium in intermediate layer 130, being isolated on both sides by layers 120, 140 of water-immiscible organic liquids of respective densities, is practically not consumed in such a process, although it may be mixed, in some embodiments, with sea-water in any ratio.

[0042] Figure 2 is a high level schematic illustration of an underwater mineral production method 200, according to some embodiments of the invention. Method 200 enables underwater sorting of crushed material by gravitationally separating by density components of the crushed material using a liquid column having a downwards increasing density (stage 220). Method 200 may comprise delivering the crushed material onto a top of the liquid column having a downwards increasing liquid density (stage 210).

[0043] The liquid column may comprise at least a bottom layer of a heavy water-immiscible liquid, an intermediate layer of an aqueous salt solution and a top layer of a light water-immiscible liquid. The heavy water-immiscible liquid may be selected to have a higher density than the aqueous salt solution, the aqueous salt solution may be selected to have a higher density than the light water- immiscible liquid and the light water-immiscible liquid may be selected to have a higher density than sea water. The downwards increasing density, with heavier liquids deeper in the column and alternating water affinity, is configured to maintain the intermediate layer on top of the bottom layer, the top layer on top of the intermediate layer and the top layer in the liquid column. [0044] In particular, method 200 comprises selecting a bottom layer of a heavy water-immiscible liquid (stage 222), selecting an intermediate layer of an aqueous salt solution (stage 224), selecting a top layer of a light water-immiscible liquid (stage 226), selecting the light water-immiscible liquid to be denser than seawater (stage 228) and selecting the liquids and solutions to build a density gradient (with the bottom layer the densest, the top layer the least dense) (stage 230).

[0045] Moreover, without being bound by theory, the higher-than-seawater density of the light water-immiscible liquid is useful in preventing dilution of the liquids (stage 229) and in removing seawater from the delivered crushed material (stage 215). Both benefits are achieved by topping the column with a water-immiscible liquid that is heavier than seawater

[0046] In certain embodiments, method 200 may comprise selecting the liquids and solution to separate a target product and trailings into different layers (stage 232), removing the target product from the respective layer in which it accumulates (stage 240) and removing the tailings from the respective layer(s) in which they accumulates (stage 245). For example, if the product is heavier than the tailings (e.g., gold ore and silicate tailings), the layers may be selected to accumulate the product in a lower layer, e.g., the bottom layer, while accumulating the tailings in a higher layer, e.g., the intermediate layers. The product and tailings may be removed from the respective layers at rates that correspond to their accumulation speeds. The form of the container holding the liquid column may be designed to permit respective volumes of product and tailings to accumulate and be removed.

[0047] In certain embodiments, method 200 of underwater mineral production may comprise ripping of the original raw minerals deposits on the sea bottom with subsequent excavation of the obtained rock mass and its stratification into mineral components of the original raw material in a heavy water-salt medium with the density exceeding that of sea-water. The rock mass scooped from the sea bottom is fed for stratification into the water-salt medium through a screening layer of water- immiscible non-aqueous layer, whose density is intermediate between the former and sea-water, whereas the sunken material is discharged through a layer of another underlying liquid with a superior density, immiscible with the aqueous medium. In non-limiting examples, sodium silicon- tungstate solution in water may be used as a heavy water-salt medium with the density intermediate between the target and waste components of the initial raw material. A mixture of hexane with perfluorocyclobutane may be used as a water-immiscible non-aqueous organic liquid screening the layer of heavy water-salt medium, through which layer the initial rock mass is submerged for the stratification of its component minerals. Bromoform may be used as a water-immiscible non- aqueous organic liquid underlying the layer of heavy water-salt medium, from which the submerged fraction of the target component of the original raw material is discharged.

[0048] In certain embodiments, method 200 may be realized by ripping and excavation of rock deposits lying on the sea bottom; transfer of the ripped rock mass roiled in sea-water into a movable container filled with a three-layer column of immiscible liquids with densities exceeding that of the sea-water; transfer of rock mass suspension in sea-water through the upper layer of non-aqueous liquid screening the layer of the working water-salt medium with a simultaneous displacement of the sea water wetting the surface of minerals that form the initial raw material by the non-aqueous liquid; stratification of minerals forming the rock mass in a water-salt working medium into a light (waste rock) and heavy (valuable component) fractions with a simultaneous displacement of residues of non-aqueous liquid (wetting them after they pass the upper layer of non-aqueous liquid) from their surface; valuable component discharge from the layer of heavy non-aqueous liquid underlying the working water-salt medium, through the sea water flooding the discharge facility; and waste rock discharge through the layer of light non-aqueous liquid screening the working water- salt medium, with a simultaneous substitution of non-aqueous liquids wetting the surface of the discharged minerals with sea-water; and delivery of the valuable component wetted by sea water on board of the commercial ship and waste rock arrangement in the worked-out space.

[0049] Advantageously, the use of method 200 may have a number of economic advantages over known technologies of underwater minerals production, since method 200 ensures the technical possibility to separate valuable minerals from waste rock immediately at the sea bottom, even if we are dealing with the production of raw ores, which allows us to avoid the delivery of the whole volume of the produced rock mass on board of the commercial ship from the sea depth, as well as permanent replenishment of the system with fresh water-salt medium with the density exceeding that of the waste rock.

[0050] In underwater mineral dressing units, systems and methods which are provided herein, material is milled in a water-immiscible liquid which is heavier than water and lighter than the product material. Gangue material is removed by the milling and floats on the water-immiscible liquid to be removed without further processing. Product containing material sinks and is further milled to remove additional gangue material, until the required level of extraction is achieved. Cascades of milling rolls in the water-immiscible liquid allow ever improving extraction of the product material. The rolls are arranged to regulate material flow through the system to remove floating gangue while directing sinking product material to further processing. [0051] Figure 3 is a high level schematic illustration of an underwater mineral dressing unit 301 and system 300 according to some embodiments of the invention.

[0052] Underwater mineral dressing unit 301 comprises a vertical vessel 310 comprising at least one pair (e.g., 311A) of a flow compartment and a milling compartment (e.g., flow compartment 310A and milling compartment 310B). Flow compartment (e.g., 310A) is positioned above and in fluid communication with milling compartment (e.g., 310B).

[0053] In certain embodiments, unit 301 may comprise a plurality of successive pairs (311A, 311B ... 311N) positioned one above the other and in fluid communication. For example, Figure 3 illustrates a succession, from top to bottom, of: flow compartment 310A, milling compartment 310B, flow compartment 310C, milling compartment 310D, flow compartment 310E etc. until flow compartment 310M and milling compartment 310N. The last compartment may be followed by a bottom compartment 310Z. The number of successive stages 311 is adapted to the required process, as explained below.

[0054] Vertical vessel 310 is filled with a water-immiscible liquid 285 selected to have a density that is intermediate between lighter gangue material and heavier product material, to float the gangue material (e.g., 290B) and to sink the product material (e.g., 290C). In case unit 301 comprises multiple successive pairs (311A, 311B ... 311N), each pair is configured to sink the product material (e.g., 290C, 290E ... 290M, 290 Y) to a lower pair and float gangue material (e.g., 290B, 290D ... 290N) to an upper pair. The term "product material" as used in the present application refers to material which contains minerals which are heavier than the surrounding material, which is referred to as "gangue material" in this application. It should be noted, that the concentration of the product material increases through unit 301, as the product material advances from compartment to compartment down vessel 310, and is sequentially stripped from more and more gangue material. Hence the distinction between product material and gangue material is a functional one, as obviously the product material from one compartment (e.g., 290C exiting 310B) contains a significant amount of gangue material (e.g., 290D) which is separated in the next compartment (e.g., 310D). As the separation proceeds, the remaining product material becomes heavier as the ratio of heavy minerals to lighter gangue increases.

[0055] Water-immiscible liquid 285 may comprise a single liquid with a constant density or a liquid column that exhibits a density gradient. The density gradient may comprise a downwards increasing density, which may increase continuously or step-wise. For example, the Density gradient may comprise several layers of different liquids, each having a higher density than liquids above it. Thus, the column may be stably layered. For example, water-immiscible liquid 285 may comprise organic liquids, halogenated organic liquids or mixtures thereof prepared to reach the required density. In the non-limiting example presented below, tribromofluoromethane CBr ₃ F) is used as water-immiscible liquid 285. Other possibilities comprise bromoform (CHBr ₃ ), tetrabromoethane (C ₂ H ₂ Br ₄ ), pentabromofluoroethane (C ₂ Br ₅ F), and their mixtures and mixtures with tribromofluoromethane. Generally, other chemically inert halogenated organic compounds with appropriate rheological, thermodynamic and hygiene and sanitary properties according to specifications may be used as water-immiscible liquid having the density intermediate between those of the target component and waste rock.

[0056] Depending on the density of the gangue material, lighter water-immiscible liquid 285 may also be used, as long as they are heavier than seawater 80, e.g., phthalic acid dibutyl ether (dibutylphthalate, density 1.05 g/cm ³ ) or a mixture of various individual organic compounds (e.g., hexane mixture with perfluorocyclobutane).

[0057] The milling compartment (e.g., 310B) comprises grinding rolls (e.g., 340B) which are configured to receive material (e.g., 290) from the flow compartment (e.g., 310A) into a volume between the rolls and direct the floating gangue material (e.g., 290B) back to the flow compartment via lateral volumes with respect to the rolls.

[0058] In case unit 301 comprises multiple successive pairs (311A, 311B ... 311N), milling roles (340B, 340D ... 340N respectively) are configured to receive material (290, 290C ... 290M respectively) from the respective flow compartments (310A, 310C ... 310M respectively) into a volume between the rolls and direct the floating gangue material (290B, 290D ... 290N respectively) back to the respective flow compartments (310A, 310C ... 310M respectively) via lateral volumes with respect to the rolls (340B, 340D ... 340N respectively).

[0059] Figures 4A and 4B are high level schematic illustrations of configurations of system 300 according to some embodiments of the invention. Figure 4A illustrates system 300 having unit 301 with a downwards increasing density of water-immiscible liquid. Figure 4B illustrates system 300 having several units 301, each with water-immiscible liquids 285A, 285B, 285C having increasing densities to successively increase the level of mineral separation. Both configurations are explained below in more detail.

[0060] Without being bound by theory, the product material hence builds a density gradient of downwards increasing density from lighter product material 290C through intermediately dense product materials 290E ... 290M to heaviest product material 290Y. In certain embodiments, the density differences of water-immiscible liquid 285 may be configured to correspond to the density gradient of the sank product material along vertical vessel 310. [0061] Embodiments of the invention comprise underwater mineral dressing system 300. System 300 comprises underwater mineral dressing unit 301, further comprising bottom compartment 310Z positioned below and in fluid communication with bottom milling compartment 310N. Bottom compartment 310Z is arranged to receive sank product material 290Y from bottom milling compartment 310N.

[0062] System 300 may further comprise a delivery unit 302 arranged to deliver material 290 to top flow compartment 310A of pair 311A. System 300 may further comprise a top discharger 350 in fluid communication with top flow compartment 310A of pair 311 A and arranged to remove the floated gangue material 290B therefrom as tailings 290A. System 300 may further comprise a bottom discharger 380 in fluid communication with bottom compartment 310Z and arranged to remove sank product material 290Y therefrom as product 290Z and, e.g., store final product 290Z in a product container 1290.

[0063] Advantageously, the invention expands the processable source of raw materials at the expense of minerals bedded on the sea bottom both in gravel and native deposits, to increase the process productivity, to reduce power consumption and to decrease the removal of heavy medium out of the technological process. This is achieved by stratification of minerals constituting the rock mass in a heavy liquid with the density exceeding that of sea water and processing the rock mass in a sea-water-immiscible non-aqueous liquid. In certain embodiments, the stratification of minerals constituting the rock mass in the heavy liquid is alternated with the destruction of the target component accretions with the waste rock realized in the same liquid with the density intermediate between them. As a result, it is possible to remove rock cuts which do not contain a significant amount of heavier ores (and are hence lighter) at an earlier stage of the dressing process, and avoid wasting energy on grinding such material. Then, the dressing products wetted with non-aqueous liquid are dragged through sea water, and the non-aqueous liquid phase washed off their surface by sea water is returned to the head of the process.

[0064] In certain embodiments, a combination of stratification of minerals forming the rock mass in water-immiscible heavy organic liquid with step-by-step reduction of their coarseness in the same non-aqueous medium allows the sea-bottom processing of not only raw minerals extracted out of friable deposits, but also that produced from beds of cemented and native rocks of any strength with an arbitrarily small fineness of mutual dispersion of their components. Since the destruction of accretions of the target component with waste rock is performed in the liquid with the density intermediate between theirs, the waste rock released as the coarseness of such poly-mineral formations is reduced. Dressing of coarse rock that is devoid of heavier minerals is prevented by floating such material out of the zone of milling bodies impact. This prevents unnecessary power consumption for further destruction of the material that does not need further reduction of coarseness any more. The combination of the working medium immiscibility with sea water and the resulting maintenance of its density at a strictly constant level not only ensures a high and stable intensity of the dressing process, but also prevents an irreversible removal of such non-aqueous working liquid out of such a highly-efficient and, at the same time, ecologically clean underwater dressing process.

[0065] Figure 5 is a high level schematic flowchart of a method 400 of underwater mineral dressing, according to some embodiments of the invention.

[0066] Method 400 comprises at least some of the following stages: delivering material for milling (stage 405), milling delivered material in a water-immiscible liquid (stage 410), selecting the water- immiscible liquid to have a density that is intermediate between lighter gangue material and heavier product material in the delivered material (stage 420), and configuring the milling to receive the delivered material at a central volume (stage 415) and to float the gangue material in the water- immiscible liquid (stage 430) and direct the floating gangue material via lateral volumes (stage 435). Method 400 may further comprise sinking the product material in the water-immiscible liquid (stage 440) and directing the product material to sink centrally (stage 445). In certain embodiments, method 400 further comprises configuring the milling to reach a specified milling grade that provides a specified product purity and separation grade (stage 460).

[0067] In certain embodiments, method 400 further comprises carrying out the milling in successive stages, each stage receiving sank product material from a previous stage and floating gangue material to the previous stage (stage 450) and processing ever more purer product material in successive stages (stage 455).

[0068] In certain embodiments, method 400 may further comprise removing floated gangue material from top lateral volumes (stage 470) and removing sank product material from a bottom central volume (stage 480).

[0069] In certain embodiments, method 400 further comprises selecting the water-immiscible liquid to exhibit a constant density. In certain embodiments, method 400 further comprises selecting the water-immiscible liquid to exhibit a downwards increasing density (stage 425) and configuring the vertical density gradient of the water-immiscible liquid to correspond to a vertical density gradient of the sank product material (stage 427).

[0070] In certain embodiments, method 400 may be realized by step-by-step accomplishment of the following main technological operations. Method 400 may begin with the delivery of rock mass produced from an underwater deposit for processing into movable vertical vessel 310 with heavy organic liquid 285, which is located in the immediate vicinity of an underwater mining face. Vessel 310 may be subdivided in the vertical dimension into a cascade of compartments, where the separation of minerals forming the initial raw material is combined each time with the reduction of the coarseness of the material.

[0071] Method 400 may further comprise discharging of waste rock floating non-aqueous heavy liquid 285 from the uppermost compartment by dragging the floating waste rock through a sea-water layer, with a subsequent placement of final tailings 290A of dressing wetted with sea water in the underwater worked-out space. During the discharge, liquid 285 is separated from seawater 80 due to its immiscibility and density.

[0072] Method 400 may further comprise discharging of the valuable component extracted from the produced raw material (i.e., product 290Y) by passing the product through sea water 80 from the bottommost compartment of the vertical container with heavy organic liquid. During the discharge, liquid 285 is separated from seawater 80 due to its immiscibility and density. The removed valuable component 290Z may be stored on the sea bottom and subsequently lifted to the board of a commercial ship.

[0073] In certain embodiments, method 400 further comprises carrying out the milling in successive units, each successive unit having a heavier water-immiscible liquid than a preceding unit (stage 453).

Example

[0074] As a non-limiting example, units 301, systems 300 and methods 400 are demonstrated for the development of underwater wolframite deposits. The density of wolframite (the product material) is 7.5 g/cm ³ , whereas the density of quartz, the main waste component (the gangue material) of the wolframite ore, is 2.6 g/cm ³ . In other examples, systems 300 and methods 400 may be used to dress additional ores or minerals such as diamonds, gold, platinum, iridium, tungsten, lead, nickel, copper, titanium, cobalt, niobium, tantalum, uranium, thorium, lanthanum, etc. These can be extracted on their own or as byproducts of the main dressed ore, as explained below.

[0075] The initial rock mass 290 produced in underwater sea face is continuously introduced by a central axial pipe (not shown, see arrow associated with 290) into the first, uppermost compartment 310A of movable underwater dressing plant 310 made in the form of a vertical vessel representing a chain of alternating separation and milling compartments. The dressing plant is flooded with tribromo-fluoromethane - water-immiscible halogenated organic liquid 285 (density - 2.7 g/cm ³ ).

[0076] Generally, pure quartz initially contained in wolframite ore and its debris may be removed prior to milling, e.g., by gravitational separation in water-immiscible liquid 285 in compartment 310A, before reaching first milling compartment 310B. Quartz may remain afloat in non-aqueous liquid 285, while wolframite fractions and its accretions with waste rock are submerged into the next, milling compartment 310B equipped with rollers 340B, where the first stage of the reduction of coarseness of this material takes place.

[0077] Waste product of such underwater dressing process that accumulates on the surface of heavy organic liquid 285 is discharged outwards by screw discharger 350 and (tribromofluoromethane 285 that wets the surface of the removed material is substituted for seawater 80 in the course of its dragging within the body of discharger 350, and flows down back into separation department 310A) used for stowage of the worked-out underwater space.

[0078] Due to counter-rotation of rollers 340B, friable flow of additionally milled material 290C leaving the gap (central volume) between them in compartment 310C is pushed out downwards, into the next separation compartment 310D, where the second stratification stage takes place in more quiet hydrodynamic conditions.

[0079] In next milling compartment 310D, additional portion 290D of pure quartz particles opened at the destruction of accretions by rollers 340D floats upwards (via lateral volumes, as directed by rollers 340D) from compartment 310D and divides, when approaching compartment 310B, into two flows one on each side of vessel 310 (counter-rotating rollers 340B create horizontal flows of liquid medium directed from the center to the periphery), floating up in its peripheral near-wall zone towards compartment 310A, to the place of waste rock removal out of the process by screw discharger 350.

[0080] Heavy material remaining in mineralogically unopened form 290E is submerged from separation compartment 310D into the next milling compartment and then passes top-down through the vertical cascade of compartment pairs until nothing remains to float from the bottommost separation compartment 310Z, and only pure tungsten concentrate 290Y is accumulated on its bottom. In certain embodiments, unit 301 may be arranged to reach different purification stages of the ore, and sequential unit 301 may be part of system 300. In certain embodiments, successive units 301 may employ water-immiscible liquids 285 of increasing densities to increase the level of purity of the product. [0081] Target product 290Y may be discharged by screw discharger 380. During the discharging process, heavy organic liquid 285 is washed off the surface of product 290Y by seawater 80 and flows back down to bottom compartment 310Z along the inner wall of screw discharger 380. Thus, the removal of heavy working liquid 285 is prevented, which, in certain embodiments, makes the underwater production cycle organized in this manner practically totally closed with respect to the heavy organic liquid used in it.

[0082] The ready tungsten concentrate 290Z may be accumulated containers 1290 and lifted in it on board of a commercial ship with subsequent delivery of this cargo to the shore for further processing into metal tungsten.

[0083] Units 301, systems 300 and methods 400 have a number of advantages over known technologies of underwater minerals dressing. First, they ensure the technical possibility of an efficient separation of the valuable mineral from waste rock immediately on the sea bottom, irrespective of the form (detritus or native) of the initial mineral bedding in the underwater deposit. Thus, systems 300 and methods 400 avoid the delivery of the whole volume of the produced rock mass 290 on board of the commercial ship from the sea depth. In certain embodiments, further separation of valuable minerals from product material 290Z may be carried out on shore, or in a dedicate unit 301 build along the same principles, with appropriate water-immiscible liquid 285.

[0084] Second, the improvements are especially significant in case of rare and valuable metals and minerals such as diamonds, gold, platinum, iridium, tungsten, lead, nickel, copper, titanium, cobalt, niobium, tantalum, uranium, thorium, lanthanum, tinstone, wolframite, galena, cinnabar, monazite etc. Since the contents of such metals or minerals in the delivered material 290 amounts to several grams per ton, the weight of the cargo lifted on board of a commercial ship from the sea bottom decreases in four to five orders of magnitude. For example, at the development of underwater deposits of bedrock gold, whose content in the raw mineral is 2-10 gram per ton, the delivery of native gold (density 19.3 g/cm ) free from the waste rock instead of raw ore on board of the commercial ship allows a reduction of tonnage of raw rock mass lifted from sea bottom per ton of ready product (recalculated per dry matter) from ca. 100,000-500,000 tons to one or two tons. The invention thus drastically reduces the price of sea-bottom development and allows using ordinary navy for underwater mining instead of floating platforms and expensive ships of high tonnage.

[0085] In certain embodiments, desalination and rinsing methods and systems are provided, which use a liquid column to efficiently perform freeze desalination and enable recyclable washing of produced minerals or combustible material. The liquid column comprises alternating layers of water immiscible liquids and salt solutions which form a vertical density gradient (e.g., a set of liquids with different densities) and exhibit a lower freezing zone from which ice floats to an upper melting zone. Cooling of introduced upwards flowing salt solutions is carried out by a countering downwards flow of cold water immiscible liquid. The process is cyclical, involves few if any mechanical moving parts and is easily controllable and adaptable to varying desalination circumstances. Rinsing of minerals or combustible material may be integrated in the heat and matter flows of the desalination system to allow effective rinsing, desalination and recycling of the used water.

[0086] Figure 6 is a high level schematic process diagram of an exemplary desalination and rinsing system 600, according to some embodiments of the invention. Figure 7 is a high level schematic illustration of processes in desalination system 600, according to some embodiments of the invention. While Figure 7 is a conceptual scheme of flows through system 600, Figure 6 is a concrete example for a possible implementation of system 600. Systems 600 and methods 700 are applicable to mineral produced, sorted and extracted in any of the above-disclosed systems 100, 300 and methods 200, 400.

[0087] Desalination system 600 comprises a vertical vessel 610 having a bottom layer 610A of a heavy water-immiscible liquid 580, a brine layer 610B with brine 590 on top of bottom layer 610A, an intermediate layer 610E of a light water-immiscible liquid 570 on top of brine layer 610B, and a top water layer 610F on top of intermediate layer 610E which comprises water and ice 560, as explained below.

[0088] A density of heavy water-immiscible liquid 580 is selected to be larger than a density of brine 590, and a density of light water-immiscible liquid 570 is selected to be smaller than a density of brine 590 and larger than a density of water and ice 560 in top water layer 610F. The density of light water-immiscible liquid 570 may be selected according to the relative proportions of water and ice in layer 610F, or be selected to be lower than ice-less water. The density of the water may be that of pure water or if water with residual dissolved salts.

[0089] In certain embodiments, sections of vessel 610 may be designed to support the processes that take place in them. For example, a freezing section 610D in brine layer 610B may be thermally insulated from its surroundings by a thermal insulation layer 612. In another example, a top part 610C of brine layer 610B may be wider than lower regions, to enable brine removal without disturbing ice floating. In yet another example, a section 610G in top layer 610F may be designed to support melting of ice 550D by heat exchanger 620. For example, heat exchanger 620 may comprise a coil-pipe 621 immersed in layer 610E of thawed water 560 accumulated as the top layer of vessel 610. The dimensions of vessel 610 and parts thereof as well as their forms and construction materials may be selected to optimize the desalination process with respect to set requirements. Vessel 610 may be constructed as a pressure vessel, and the liquid column may be pressurized.

[0090] In certain embodiments, a four-layer column is formed in the vertical working vessel during the pre-starting period. It consists of alternating water-immiscible and aqueous layers with decreasing densities (at working conditions) from the bottom to the top of the vessel (580, 590, 570, 560 respectively). The liquids may be poured successively in the order of decreasing densities with the subsequent continuous delivery of a fresh flow of the brine (550C) to be desalinated to the bottommost non-aqueous layer (610A). Simultaneously, a part of the heaviest non-aqueous liquid (580A) may be withdrawn into the external circulation loop through a refrigerating machine (640) and then returned into the over-lying brine layer (610B) which is screened by a layer of a lighter non-aqueous liquid (610E) with an intermediate density between those of the brine and clean water, which is flooded with a layer of thawed water (610F). Ice 550D that floats into the uppermost freshwater layer (610F) is melted by heating the thawed water by blind heat exchange using the dilute water-salt solution (550A) fed for desalination, while the produced excess of fresh water is continuously delivered to the consumers. Strong brine 590A may be removed from brine layer 610B as an additional final product 590B.

[0091] Examples for heavy water-immiscible liquid 580 comprise any water-immiscible low- freezing organic compounds or their mixtures with the density exceeding that of the brine to be concentrated, such as perfluoroheptane (density 1.733 g/cm ³ , boiling point 82.5°C, freezing temperature -78°C, in case of a non-limiting example in which brine 590 has a density up to 1.700 g/cm ³ ), hexane mixtures with tetrafluorodibromoethane, or mixtures thereof.

[0092] Additional examples for heavy water-immiscible liquid 580 may comprise organic compounds related to halogenated derivatives of aliphatic hydrocarbons, such as, e.g., cis- dibromoethylene (density 2.28 g/cm , boiling point 112.5°C, freezing temperature -53°C) and their various mixtures. For example, a mixture of carbon tetrachloride (49% by volume) with chloroform (51% by volume) (freezing temperature: -81 °C) can be used as heavy water-immiscible liquid 580, as well as even lower-freezing high-density compositions, such as the non-limiting examples listed below (the amounts of components are given in % by volume): (i) chloroform 31%, trichloroethylene 69%; (ii) chloroform 27%, methylene chloride 60%, carbon tetrachloride 13%; (iii) chloroform 20%, trans- 1,2-dichloroethylene 14%, trichloroethylene 21%, ethyl bromide 45%; (iv) chloroform 14.5%, methylene chloride 25.3%, ethyl bromide 33.4%, trans- 1,2-dichloroethylene 10.4%, trichloroethylene 16.4%. Other mixtures may be used according to specific requirements and according to the principles described above. [0093] Examples for light water-immiscible liquid 570 comprise any organic liquids or mixtures of several organic liquids with an intermediate density between those of thawed water and water-salt medium (i.e., brine 590), such as phthalic acid dibutyl ether (dibutyl phthalate) (density 1.05 g/cm ³ , boiling point 340°C, freezing temperature -35°C) or furfural (density 1.16 g/cm ³ , boiling point 161.7°C, freezing temperature -36.5°C) can be used, as well as various compositions made up from different organic ingredients, such as, e.g., a mixture of hexane (density 0.66 g/cm ³ , boiling point 69°C, freezing temperature: -94°C) with tribromofluoromethane (density 2.71 g/cm ³ , boiling point 105°C, freezing temperature -74°C), or a mixture of pentane (density 0.63 g/cm , boiling point 36.1°C, freezing temperature -129.7°C) with tetrafluorodibromoethane (density - 2.16 g/cm , boiling point 47.3°C, freezing temperature: -110.5°C).

[0094] In certain embodiments, some or all layers 610A, 610B, 610E and 610F have a vertically uniform density. In certain embodiments, one or more of layers 610A, 610B, 610E and 610F may have a vertically variable density (i.e., a bottom part with a density higher than an upper part) to support heat exchange and ice floating. The temperatures and possibly pressures of the liquids in the system may also be adapted to support and optimize heat exchange and ice floating.

[0095] Desalination system 600 further comprises a brine handling unit 615, arranged to introduce brine 550C into bottom layer 610A and remove concentrated brine 590A from brine layer 610B.

[0096] Desalination system 600 is arranged to freeze water in brine layer 610B and enable floating of ice 550D from brine layer 610B through intermediate layer 610E to top water layer 610F.

[0097] In certain embodiments, desalination system 600 further comprises a cooling unit 640 arranged to cool heavy water-immiscible liquid 580A from bottom layer 610A and introduce cooled heavy water-immiscible liquid 580B into brine layer 610B. Introduction of cooled heavy water- immiscible liquid 580B into brine layer 610B may promote or cause freezing of water in brine 560 to yield ice 550D, that may then float to water layer 610F.

[0098] In certain embodiments, cooling unit 640 may be arranged to cool heavy water-immiscible liquid 580A using water and/or ice 550E removed from top water layer 610F. For example, excessive water due to melting ice 550D may be delivered to cool heavy water-immiscible liquid 580A, or heavy water-immiscible liquid 580A may be transferred through a heat exchanger in thermal contact with top layer 610F or with water and/or ice therefrom.

[0099] Cooling unit 640 may be a refrigerator that receives relatively cold water 550E (as the melt product 550E from ice 550D) at heat exchanger 640A, and relatively warm heavy water-immiscible liquid 580A (which was warmed by water 550C introduced into layer 610A) at heat exchanger 640B. The respective heat exchangers 640A, 640B yield respectively warmer water 550F delivered e.g. to rinsing unit 595 and cooled heavy water-immiscible liquid 580B delivered to layer 610B to cool introduced water 550D. In certain embodiments, cooling unit 640 may use a coolant that is pumped between heat exchangers 640A, 640B by pumping unit 640C to deliver heat between liquids 550 and 580. In certain embodiments, cooling unit 640 may comprise a single heat exchanger providing direct contact between liquids 550, 580.

[00100] Desalination system 600 may further comprise at least one pre-cooling unit (e.g., 620, 630, see below) arranged to cool introduced brine 550A prior to its introduction into bottom layer 610B. For example, desalination system 600 may comprise a cooling unit 620 arranged to melt floated ice 50D in top water layer 610F to cool introduced brine 550A and/or a heat exchanger 630 arranged to use removed concentrated brine 590A to cool introduced brine 550A or 550B. Introducing pre- cooled brine 550C into vessel 610 may promote freezing of water in brine 560 to yield ice 550D, that may then float to water layer 610F.

[00101] In certain embodiments, pre-cooled brine 550C is introduced into bottom layer 610A and further cools by rising through bottom layer 610A, which is cooled by cooled heavy water- immiscible liquid 580B. Such implementation may result in countercurrent further cooling of introduced brine 550C which may be designed to lead to water freezing. While pre-cooled brine 550C may also be introduced into brine layer 610B and cooled heavy water-immiscible liquid 580B may also be introduced into bottom layer 610A, the countercurrent of these flows, as illustrated in Figures 6 and 7 may further enhance the cooling of introduced brine 550C and the process's overall efficiency.

[00102] In certain embodiments, pre-cooled dilute water-salt solution 550C is concentrated during its flow from layer 610A to 610F, and separated into brine (590 and 590A) and fresh (or more dilute) water (ice 550D, water 560 and 550E). Water 550C is delivered into layer 610A of heavy water-immiscible liquid 580, e.g., into the bottommost zone of layer 610A which is the base of the entire multi-step column of liquids. Due to the immiscibility of liquid 580, pre-cooled dilute water- salt solution 550C irreversibly floats up in layers 610A and 610B and is additionally cooled at the expense of mixing recuperative cold-exchange between media 580, 590 and water 550C. As a result, by the moment water 550C approaches layer 610E, its temperature decreases down to that of the beginning of ice crystallization out of it. In embodiments, formation of ice 550D may commence in any of layers 610A, 610B and 610E, depending on the process design. Since the continuous floating water-salt liquid 550C is washed by immiscible non-aqueous medium 580B, adequate conditions for the start of massive ice formation may be arranged to start in layer 610B and not in layer 610A. Generated ice 550D floating from layers 610A and/or 610B may be incorporated in dilute water-salt solution 550C before the commencement of massive ice formation. Freezing promotes further floating as ice density is smaller than water density. Upon rising be floating, ice 550D becomes coarser due to the start of massive ice formation caused by a deeper cooling of brine 590, and brine 590 is thus desalinated at the expense of counter-flow mixing cold-exchange with non-aqueous refrigerating agent 580B in layer 610B.

[00103] Without being bound by theory, fresh refrigerating agent 580A (e.g., perfluoroheptane) used in this process, which is collected after the main two-step mixing cold-exchange at the base of layer 610A, is introduced as cooled refrigerating agent 580B, after restoring its refrigerating potential in a refrigerator 640, into the uppermost zone of layer 610B, e.g. into layer 610D. This assures a common counter-flow of cold-exchanging phases (580B and 550C). Being heavier than water-salt medium 590 in layer 610B, cold heavy water-immiscible liquid 580B (e.g., perfluoroheptane) sinks in it, transferring its coldness to water-salt medium (550C and 590). Ice granules 550D floating up in the opposite direction are additionally cooled and continue coarsening, since while they are floating up, the external spherical surface of ice acquires increasingly low temperature due to counter-flow of non-aqueous refrigerating agent 580B sinking in water-salt medium 590 and further sinking in heavy water-immiscible liquid 580 of layer 610A (due to its coldness). As a result, further uniform layered ice freezing takes place on the still cooled surface of floating ice granules. At that, a stably high motivating force of cold-exchange is maintained. Hence, it is due to such a counter-flow between cold-exchanging phases organized by feeding fresh refrigerating agent 580B towards floating ice 550D that the ice-formation intensity is maintained, in contrast to known methods of brine desalination, at a stably high level.

[00104] The removal of heavy water-immiscible liquid 580A that has exhausted its cooling potential from the cold-exchange process may be realized from the lower zone of layer 610A by pumping this low-freezing liquid using pump 642 through heat exchanger 640B (e.g. an evaporator) of refrigerator 640. There, refrigerating agent 580A is cooled down to the temperature level required for concentrating the desalinated brine up to the necessary strength. After that it may enter the upper zone of layer 610B to concentrate water-salt medium 590 as described above.

[00105] In certain embodiments, desalination system 600 may further comprise a water removal unit 645 arranged to remove water and/or ice 550E from top water layer 610F. Remove water and/or ice 550E may be used to cool heavy water-immiscible liquid 580A in cooling unit 140, may serve as a product of system 600, or may be used in a rinsing unit 595 as described below. [00106] Desalination system 600 may further comprise rinsing unit 595 arranged to remove brine 550A from delivered material 541 using water 550F from removed water and/or ice 550E (with or without using it as a cooling medium), and deliver removed brine 550A to brine handling unit 615.

[00107] In certain embodiments, the desalination system may be part of a rinsing system 600, and operate to recycle the water used during the rinsing. For example, water 550F may be used to concentrate or sort minerals or combustible material, or to carry out mechanical, thermal or chemical processes relating to minerals or combustible material. For example, brine 590 may be used as the water-salt medium described in U.S. Patent Application No. 13/956,418, which is used to gravitationally separate coal from waste rock, and desalination system 600 may be incorporated in the combustible material processing system described therein to treat and recycle the water-salt medium used there. As an example, an implementation of the rinsing operation is illustrated in Figure 6 as rinsing unit 595, having a belt conveyor 595C such as band vacuum-filters which receive water 550F as a dilute water-salt solution at the ambient temperature. The rinsing water is collected (at collectors 595B) at different locations along conveyor 595C and is pumped by pumps 595A to rinse material 541 upstream on band 595C (in the illustrated case). In certain embodiments, delivered water 550F may be delivered directly from water layer 610F as water 550E (in certain embodiments, water 550E may be used for cooling heavy water-immiscible liquid 580A as explained above). Hot air 540 may be used to heat delivered water 550F and melt, if needed, ice delivered therewith. The heated water may then be delivered as water 50A for pre-cooling and melting ice within water layer 610F itself. Hot air 540 may also be used for final drying of delivered material 541 to yield dry material 542.

[00108] The uptake of regenerated strong brine 590A fed through recuperative cold-exchanger 631 to pump 634 as concentrated brine 590B for disposal or further concentration. Uptake of brine 590A may be carried out from the upper (somewhat expanded) zone 610C of layer 610B in the central part of vertical vessel 610. Zone 610C may by purposely made with a greater diameter in order to avoid the entrainment of ice 550D floating up vertically into next layer 610E of non-aqueous liquid 570 to eventually by melted and/or leave vertical vessel 610. In certain embodiments, liquid 570 may be a water-immiscible non-aqueous physiologically inert liquid that does not freeze at the temperature of ice floating up in it and has the density intermediate between those of water-salt solution and fresh water, such as dibutyl phthalate. At that, while ice 550D passes through layer 610E of dibutyl phthalate 570, residues of moistening water-salt medium (590, 550C) are washed off the surface of ice granules. Therefore, after passing through layer 610E, overcooled ice 50D continues floating up (being already clean and free of water-salt solution) to layer 610F of fresh water 560 heated by fresh rinsing water 550A delivered to the freezing-out process at the ambient temperature.

[00109] Figure 8 is a high level schematic flowchart illustrating a desalination method 700 according to some embodiments of the invention. Desalination method 700 may comprise freezing ice in a brine layer (stage 710) by introducing a cooled heavy water-immiscible liquid into the brine layer (stage 730), wherein the heavy water-immiscible liquid is selected to have a density which is larger the brine density (stage 735), and gravitationally removing the ice from the brine layer (stage 715) by floating the ice through a light water-immiscible layer (stage 720) which is selected to have a density which is intermediate between the brine density and water density (stage 725). Method 700 may further comprise maintaining the intermediate layer of light water-immiscible liquid between the brine layer and the top water layer (stage 727).

[00110] Desalination method 700 may further comprise maintaining a bottom layer of heavy water- immiscible liquid below the brine layer (stage 737) and introducing brine into the bottom layer of the heavy water-immiscible liquid (stage 750) positioned below the brine layer. Desalination method 700 may further comprise cooling the introduced brine prior to its introduction into the bottom layer (stage 760), e.g., by removing concentrated brine from the brine layer (stage 762) and cooling the introduced brine by concentrated brine which is removed from the brine layer (stage 765). In certain embodiments, desalination method 700 may further comprise cooling the introduced brine (stage 760) by the top water layer that receives the floated ice from the light water-immiscible layer (stage 770). In such embodiments, the introduced brine may be used to melt the floated ice (stage 775).

[00111] Desalination method 700 may comprise cooling heavy water-immiscible liquid from the bottom layer for the introduction into the brine layer (stage 740), e.g., by water and/or ice removed from the top water layer positioned above the light water-immiscible layer (stage 745).

[00112] In certain embodiments, desalination method 700 may comprise removing water and/or ice from the top water layer (stage 780), rinsing delivered material by the removed water (stage 790), removing brine from delivered material using the removed water (stage 795) and delivering the removed brine to the brine layer (stage 797).

[00113] In some embodiments, method 700 is realized by a step-by-step accomplishment of the following main operations: (i) initial step-by-step bottom- up filling of the vertical vessel starting from the heaviest liquid (e.g., perfluoroheptane) up to the lightest one (fresh water) obtaining a four- layer column of two pairs on immiscible aqueous and non-aqueous liquids; (ii) organization of permanent perfluoroheptane circulation over the external refrigerating loop from the bottom layer through the refrigerator into the upper zone of the overlying layer of the brine to be desalinated with the subsequent output of strong water-salt concentration product out of the desalination process since the moment when the ice starts to freeze out; and (iii) heating of thawed water in the uppermost fresh-water layer of the upper pair of immiscible liquids by blind heat exchange with the initial dilute water-salt solution, which involves melting of ice continuously floating through all underlying liquid layers, which is frozen out of the brine, and a subsequent delivery of fresh water permanently accumulated at the top of this cascade to customers.

[00114] In certain embodiments, method 700 may further comprise controlling operation parameters by adjusting at least one of a quantity and a density of at least one of the heavy and light water-immiscible liquids (stage 799). For example, increasing an amount of liquids 580 and/or 570, reducing their density or increasing their viscosity (e.g., by mixing other liquids into respective layers 610A, 610E) prolongs the time heat is exchanged with water 550C and the time ice 550D floats through layer 610E, respectively.

[00115] Advantageously, the disclosed systems and methods are much more efficient and productive than other freeze desalination methods in that ice is formed within the brine and does not accumulate on the vessel walls. Furthermore, the present invention does not require either any special mechanical facilities containing moving parts or any cyclic operations, as do known desalination processes. The invention allows fresh water production in a continuous mode with a high efficiency and economic consumption of power resources without any risk of breaking working vessel in which the desalination process is realized.

[00116] Advantageously, the disclosed systems and methods provide closed regeneration cycles for water 550 and for heavy medium 580, which may be practical in various industries, e.g., for coal separation from waste rock. At proper production standards excluding its mechanical losses, such organization of coal concentration sets a coal concentration factory using such technology free from irreversible consumption of a respective amount of mineral salts required for replenishment of heavy water-salt liquid in its circulation loop. Furthermore, in comparison with known processes of water- salt solutions desalination, certain embodiments of the disclosed systems and methods exhibit significant process intensification, a higher level of energy perfection and absence of any mechanical facilities comprising moving parts for discharging ice from the place of its freezing-on. It is as important that such technological process does not involve any internal factors that can lead to breakdown of principal equipment used for its realization.

[00117] In certain embodiments, the invention may be of special interest for coal producing and coastal countries with severe weather conditions in winter. In this case, there is a direct opportunity of rational use of natural coldness for ice freezing out of dilute water-salt solutions (both of industrial origin and for sea water desalination) with the purpose of electric power saving. Just because of this, vertical working vessel 610 for the realization of the desalination process is equipped with removable cold insulation 612 that can be dismantled from its internal surface in winter. An additional advantage of the process is its high technological flexibility and easy adaptability to any technological disturbances arising in the system and changing external conditions. For this purpose, one can smoothly control the height of separate layers 610A, 610B, 610E, 610F inside such multi-layer column of liquids, and vary the densities used in each of nonaqueous liquid layers 580, 590, 570, 560. Besides, these corrections can be introduced into the desalination operation in the process of brine desalination, without stopping its principal production activity.

[00118] The following are non-limiting examples for the above, namely ways to influence process parameters by simple changes. For example, to prolong the time ice remains at the stage of washing residues of water-salt medium from its surface, one should only pour additional light water- immiscible liquid 570 (e.g., dibutyl phthalate) into layer 610E of the cascade without stopping the desalination process. In another example, to increase the velocity of dilute water-salt solution 550C floating up in bottommost layer 610A of heavy water- immiscible liquid 580 (e.g., perfluoroheptane), one can introduce, e.g., a heavier liquid (e.g., add tribromofluoromethane or tetrafluoro- dibromoethane) into heavy water-immiscible liquid 580 in the course of the process. On the contrary, to slow down the floating, heavy water-immiscible liquid 580 (e.g., perfluoroheptane) can be slightly diluted with a lighter liquid, e.g., dibutyl phthalate.

[00119] In certain embodiments, in order to prolong the time of recuperative cold-exchange between heavy water-immiscible liquid 580 (e.g., perfluoroheptane) leaving the desalination process and the initial dilute water-salt solution 550C floating up in it, it is sufficient to increase the height of this layer (e.g., layer 610A and/or layer 610B) or increase it height with a simultaneous introduction of, for example, hexane into heavy water-immiscible liquid 580. Such simple approaches allow easy control of the process in other cascade layers, as well, using the same principles.

[00120] In the above description, an embodiment is an example or implementation of the invention. The various appearances of "one embodiment", "an embodiment", "certain embodiments" or "some embodiments" do not necessarily all refer to the same embodiments.

[00121] Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment.

[00122] Certain embodiments of the invention may include features from different embodiments disclosed above, and certain embodiments may incorporate elements from other embodiments disclosed above. The disclosure of elements of the invention in the context of a specific embodiment is not to be taken as limiting their used in the specific embodiment alone.

[00123] Furthermore, it is to be understood that the invention can be carried out or practiced in various ways and that the invention can be implemented in certain embodiments other than the ones outlined in the description above.

[00124] The invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.

[00125] Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined.

[00126] While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention. Accordingly, the scope of the invention should not be limited by what has thus far been described, but by the appended claims and their legal equivalents.