Method of apparatus for condensing metal vapours using a nozzle and a molten collector

Abstract

Methods and apparatus for condensing vapour phase compounds or elements, typically metals such as magnesium, obtained by reduction processes.

Claims

1. Apparatus for condensing vapour comprising: a source of gas comprising the vapour, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, characterized in that the collection medium is a salt flux which has a specific gravity lower than that of the condensed droplets or particles so that in operation the condensed matter settles into a portion of the bath below the condensed liquid.

2. The apparatus of claim 1, wherein the collection medium is a molten liquid.

3. The apparatus of claim 1, wherein the collection medium is disposed in a bath.

4. An apparatus for condensing vapour comprising: a source of gas comprising the vapour, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, characterised in that means are provided for continuously moving the collection medium through a location at which the beam impinges onto the collection medium, said means comprising a collection medium bath which is provided with a weir over which the liquid collection medium can flow to form a sheet of travelling collection medium on which the beam of condensed vapour impinges, and wherein the nozzle is disposed so as to direct the beam of droplets or particles onto the sheet of liquid falling under gravity from the weir.

5. The apparatus of claim 4, wherein the nozzle is disposed so as to direct the beam of droplets or particles generally horizontally with respect to the collection medium.

6. The apparatus of claim 4, wherein means are provided for re-circulating collection medium into the bath after overflowing the weir.

7. An apparatus for condensing vapour comprising: a source of gas comprising the vapour, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, wherein the collection medium is disposed in a bath, and characterized in that means are provided for circumferentially stirring the collection medium in the bath.

8. The apparatus of claim 7, wherein the liquid is circulated by a mechanical means.

9. An apparatus for condensing vapour comprising: a source of gas comprising the vapour and comprising reactive gas and/or a carrier gas, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, wherein the nozzle is configured so that on exiting the nozzle the droplets or particles form a first cone and the carrier and/or reactive gases form at least one further cone, the angle of divergence of the first cone being less than an angle of divergence of the second cone, so that the first cone is inside the second cone, and characterized in that a baffle means is provided at a location so that it is disposed around the first cone and inside the second cone so as to provide a physical barrier which helps isolate the carrier and reactive gases from the condensed droplets or particles which pass through the baffle means into the collection medium.

10. The apparatus of claim 9, wherein the baffle means is disposed around the location at which the beam of condensed particles or droplets impinges the collection medium.

11. The apparatus of claim 9, wherein the baffle means comprises an axially elongate conduit, the walls of which provide separation of the first cone from the second cone.

12. The apparatus of claim 9, wherein the baffle means is surrounded by a shoulder region which covers at least a portion, or all, of the remaining surface of collection medium.

13. An apparatus for condensing vapour comprising: a source of gas comprising the vapour and comprising reactive gas and/or a carrier gas, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, characterized in that the nozzle is configured and/or oriented so that the beam of droplets or particles impinges onto the collection medium at an oblique angle with respect to the medium surface.

14. The apparatus of claim 13, wherein the collection medium is disposed in a bath and the obliquely oriented beam impinges onto the collection medium at a location radially spaced apart from a central rotational axis of medium in the bath, so that the momentum thereby transferred to the collection medium assists or cause circumferential flow of the collection medium in the bath.

15. The apparatus of claim 1, wherein the nozzle is symmetric about a longitudinal rotational axis.

16. An apparatus for condensing vapour comprising: a source of gas comprising the vapour and comprising reactive gas and/or a carrier gas, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, characterized in that the nozzle is elongate in a transverse direction so that the beam of droplets or particles is provided in a generally planar or wedge-shaped form and so that the beam impinges onto the collection medium along an elongate contact region.

17. An apparatus for condensing vapour comprising: a source of gas comprising the vapour and comprising reactive gas and/or a carrier gas, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon, characterized in that the liquid collection medium comprises a thin sheet of a first liquid disposed above a second liquid, the sheet being sufficiently thin to be disrupted by impinging condensed droplets or particles, to the extent that the sheet parts in a region corresponding to the impingement so as to reveal a surface of the second liquid and permit direct access of the condensed particles or droplets to the underlying second liquid for absorption therein, and wherein the thin sheet remains as a protective covering over a remaining portion of the surface of the second liquid.

18. The apparatus of claim 17, wherein the first liquid comprises a salt flux.

19. The apparatus of claim 17, wherein the second liquid comprises the condensed vaporous material.

20. The apparatus of claim 17, wherein the second liquid is a molten metal.

21. The apparatus of claim 1, wherein the vapour comprises a metal or metallic material.

22. The apparatus of claim 21, wherein the vapour is a metal selected from Mg, Zn, Sn, Pb, As, Sb, Bi, Si, Cd, and combinations thereof.

23. The apparatus of claim 17, wherein the second liquid comprises molten magnesium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart scheme for an integrated magnesium extraction and casting process which utilises the vapour condensation process and apparatus of the present invention.

(2) FIG. 2 is a schematic representation of a condensation chamber according to a first embodiment of the invention.

(3) FIG. 3 is a schematic representation of a condensation chamber according to a second embodiment of the invention.

(4) FIG. 4 is a schematic representation of a condensation chamber and ancillary apparatus in accordance with a third embodiment of the invention.

(5) FIG. 5 is a schematic representation of a condensation chamber and ancillary apparatus in accordance with a fourth embodiment of the invention.

(6) FIG. 6 is longitudinal cross-section through an annular de LaValle nozzle.

(7) FIG. 7 is a schematic representation of an embodiment of the invention having no baffle or cylindrical plate.

(8) FIG. 8 is a schematic representation of an embodiment of the invention having an axially asymmetric nozzle, a transversely elongate waist, and a divergent skirt portion.

FIRST EMBODIMENT

(9) As shown in FIG. 1 a carbothermic reduction furnace flue (10) feeds a mixture of magnesium vapour and carbon monoxide to the de Lavalle nozzle (11) of a condensing chamber (described hereinafter in more detail with reference to FIGS. 2 to 5. The nozzle directs Mg mist (liquid droplets) and carbon monoxide reaction gas to impinge upon a molten salt bath collector (12). Carbon monoxide is diverted to a condensate trap/demister (13) known in the art. Metal solids entrained in the CO are recycled. Carbon monoxide is drawn into trap (13) via a vacuum pump (14) and/or steam ejectors. The collected CO is compressed for use by means of a compressor (15). The primary function of the trap is to move any liquid droplets and particulates from the gas phase to protect the vacuum pump or ejectors.

(10) Molten magnesium is tapped from a bottom end of the collector and conveyed to a magnesium settling furnace (16). Any molten salt coveyed with the metal is tapped away to a salt settling furnace (18). The molten magnesium is then conveyed to a casting stage (17) for casting into ingots.

(11) Molten salt is continuously tapped from the collector (12) and conveyed to the settling furnace where any stray magnesium is tapped away and returned to the magnesium settling furnace (18). Fresh salt (19) is pre-heated and fed into the settling furnace. Excess salt may be removed via a bleed valve (20). Salt is returned from the furnace (18) to the salt bath collector (12).

(12) The condenser chamber and nozzle are described in more detail with reference to the FIG. 2. The condenser chamber 99 is a generally cylindrical vessel having frusto-conical upper and lower ends. The carbon monoxide and magnesium vapour enters the upper convergent entry 100 of nozzle 110. The gas mixture is accelerated to supersonic speed in the core of the nozzle and then expands and cools in the lower divergent exit 101 of the nozzle. The gas mixture expands in a focussed double cone shape (not shown) with a common top point almost coinciding with the apex of the divergent cone-shaped expansion exit of the nozzle. An inner cone is substantially made up of magnesium mist and an outer coaxial cone is substantially made up of carbon monoxide.

(13) Due to the phase change from gas to liquid, the metal part of the gas stream will collapse towards the centre of the stream into a cone-shaped, focused metal mist on exiting the nozzle thus pushing the carbon monoxide, or any other gas, to the outside of the stream. This focus of the metal causes it to impinge onto the central portion of the bath through the aperture 107.

(14) An annular flange disc 104 covers the upper surface of a molten salt bath 105. The composition of the salt bath is discussed hereinafter. An upstanding cylindrical baffle 106 surrounds a central aperture 107 in the flange disc. The baffle is sized and located to lie just outside the magnesium metal cone (not shown) so that the walls are not being impinged on directly by magnesium metal drops or solids.

(15) The walls of baffle 106 will however cut off the major part of the CO gas jet stream, thus avoiding an intimate mixture between the two components. This helps reduce any back reaction. The carbon monoxide diverted outside of the baffle is drawn out to via vacuum pump 114.

(16) A lower end of the baffle feeds via the aperture 107 into an exposed upper surface 108 of a molten salt bath designated circulating salt bath. The magnesium mist thus impacts the salt bath and coalesces into droplets which fall down to a lower region of the vessel.

(17) The effective angle of impact of the metal mist on to the surface of the liquid salt may be adjusted by adjusting the speed of rotation of the salt bath, FIG. 2. The surface of the salt bath will ideally, through the rotation, assume the form of a depressed elliptic paraboloid 130. Thus the metal mist impacts at an oblique angle represented by the incline of the salt bath depressed profile.

(18) Thus, when the rotational axis is aligned with the axis of symmetry of the nozzle, the angle of impact of the cone-shaped metal mist depends on the shape of the paraboloid. This in turn is controlled by the rotational speed of the molten salt. The salt surface contour shape will, at slow speeds, assume a wide opening paraboloid and a steeper shaped paraboloid on increased rotational speed.

(19) Molten magnesium 131 settles to a lower portion of the salt bath due to its higher specific gravity. This may be tapped off under gravity by opening of a tap valve 132.

(20) A double skin water cooling jacket vessel 133 surrounds the salt bath to provide external cooling and temperature control. The vessels can be made from steel or nickel alloys. Water, stream, synthetic heat transfer liquids such as Dowtern, liquid metals such as mercury, or other suitable materials. These can be used inside the jackets to remove heat from the salt and keep it at a temperature which is suitable to remove the energy dissipated when the metal stream impacts the salt bath.

(21) The condenser chamber is equipped with a heater (not shown), which can be internal or external of the condenser chamber. This is for temperature control of the salt during start up and shut down of the unit. Under steady state operation, the heater will be off as heat is provided from the vapour entering the system.

SECOND EMBODIMENT

(22) In FIG. 3 an alternative embodiment is shown in which like features are given the same numbers as used in relation to FIG. 1. In this embodiment an upstanding perforated tube 140 is disposed in a centre region of the salt bath. The molten salt surrounds the tube. A void is present in the tube (at the ambient gas pressure of the upper gas chamber). An upper region 141 of the tube is formed with apertures or perforations which allow molten salt to cascade down the interior of the tube. Salt is continuously pumped up from a lower salt reservoir 143 via conduit 144. This maintains the salt level in bath 105, notwithstanding the volumes descending in the tube 140.

(23) The magnesium mist cone beam is directed into the interior of the tube and impacts on the continuously falling molten salt. The magnesium then falls via the tube into the lower salt reservoir 143 and settles as a coalesced mass of liquid magnesium 131.

(24) This arrangement ensures that a constantly moving surface or veil of falling salt is provided on which the mist beam can impinge onto. The gas evacuated through the gas ducts is scrubbed of entrained magnesium droplets or particles in a separate unit.

THIRD EMBODIMENT

(25) In FIG. 4 a third embodiment is shown in which a salt bath is provided with an overflow weir 150. The nozzle enters the condensing chamber in a radial transverse direction. Thus a mist beam impinges onto the sheet or veil of moving salt cascading over the weir. The salt and entrained solid or liquid magnesium particles fall into a weir pool 156 below the weir. The mixture is continuously fed from the weir pool into the salt bath at an inlet 152 via salt pump 151 and a heat exchanger 152 which extracts heat from the salt. Metal droplet 158 feed into the salt bath along with the salt.

(26) Baffles 154 define a tortuous path for the salt from the inlet to the weir 150. The baffles 154 provide obstructions and surfaces upon which entrained magnesium may coalesce and then fall to a lower portion 155 of the bath. The magnesium may be pumped from the lower portion to a magnesium settling furnace 157.

(27) Salt level control sensors/controllers (LC) and temperature (TC) and pressure (PC) sensors/controllers are provided to maintain the required levels, temperatures and pressures.

(28) A salt make-up feeder 159 may be used to adjust the salt composition within the required specification (cf. Table 2).

FOURTH EMBODIMENT

(29) FIG. 5 shows another embodiment which is a variation of the embodiment of FIG. 4. In this embodiment the nozzle 110 is directed to generate a beam which is directed onto an outer circumferential region 160 of the salt bath. The nozzle may be directed at an oblique angle to the salt bath surface so as to promote circumferential circulation. Overflow from weir 150 and the action of return pump 151 provides a further circulation of salt in the bath.

(30) For all embodiments this invention includes secondary vessel(s) as required for (1) the settling of magnesium particles or droplets from the fused salt, (2) heat control, and (3) removal of particulates and droplets from the gas stream to enhance recoveries and to protect downstream equipment.

FIFTH EMBODIMENT

(31) The fifth embodiment is shown in FIG. 7 and is a variant of the arrangement shown in the first embodiment of the invention in FIG. 2. In this embodiment there is no baffle or cylindrical plate. The bulk of the collection medium comprises molten metal (magnesium) 205. A relatively thin layer of salt flux (204) is disposed on the upper surface of the molten metal. In use the beam of droplets or particles exiting from the nozzle 110 impinges on the collection medium and disrupts the salt flux layer so as to expose underlying molten metal. Thus, after start-up, the beam impinges directly onto the revealed molten metal surface 206 in the central region of the condensing chamber. The salt flux remains covering the remainder of the molten metal around the centre and provides a protective layer which prevents oxidation or contamination of the underlying metal.

SIXTH EMBODIMENT

(32) The sixth embodiment is shown in FIG. 8 which is an alternative nozzle arrangement. The nozzle is axially asymmetric, and includes a transversely elongate waist 210 and divergent skirt portion 211. The skirt portion defines a generally oblong exit orifice 212 of the nozzle. This configuration provides a generally planar or wedge shaped beam (215) of condensed droplets or particles. Thus the beam impinges upon an associated collection medium (not shown) along a length thereof, rather than at a point. This asymmetric nozzle may be used in any of the preceding embodiments in place of a conventional symmetric nozzle. It is however particularly suited to the arrangement shown in FIG. 4 in which a travelling sheet or veil 150 of collection medium is provided to collect the condensed droplets or particles impinging thereon. In this case the beam is directed to impinge transversely across the falling sheet, whereby efficient adsorption of the metal particles/droplets may take place.

(33) The present invention can be represented in one or more of the following aspects.

(34) Aspect 1: A method for condensing a vaporous material comprising providing a gas stream comprising the vapour, passing the gas stream through a nozzle which has an upstream converging configuration and a downstream diverging configuration so that the vapour accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, wherein the beam of droplets or particles is directed to impinge onto a molten liquid collection medium.

(35) Aspect 2: A method as described in aspect 1 wherein the collection medium is maintained at a temperature above the melting point of the condensed vaporous material.

(36) Aspect 3: A method as described in aspect 1 or 2 wherein the collection medium is a molten bath.

(37) Aspect 4: A method as described in any of the preceding aspects wherein the collection medium comprises a salt flux which has a specific gravity lower than that of the condensed vaporous.

(38) Aspects 5: A method as described in any of the preceding aspects wherein the liquid collection medium comprises a thin sheet of a first liquid disposed above a second liquid, the sheet being sufficiently thin to be disrupted by impinging condensed droplets or particles, to the extent that the sheet parts in a region corresponding to the impingement so as to reveal a surface of the second liquid so as to permit direct access of the condensed particles or droplets to the underlying second liquid for absorption therein, and wherein the thin sheet remains as a protective covering over a remaining portion of the surface of the second liquid.

(39) Aspect 6: A method as described in aspect 5 wherein the first liquid comprises a salt flux.

(40) Aspect 7: A method as described in aspect 5 or 6 wherein the second liquid comprises liquid condensed vaporous material.

(41) Aspect 8: A method as described in any of aspects 5 to 7 wherein the second liquid is a molten metal.

(42) Aspect 9: A method as described in any of the preceding aspects wherein the collection medium comprises a moving sheet of liquid.

(43) Aspect 10: A method as described in aspect 9 wherein the moving sheet is a stream of liquid falling under gravity.

(44) Aspect 11: A method as described in aspect 9 or 10 wherein the moving sheet is provided by an overflowing ledge region of a collection medium reservoir.

(45) Aspect 12: A method as described in any of aspects 9 to 11 wherein the nozzle is directed horizontally or substantially horizontally towards the sheet of liquid collection medium.

(46) Aspect 13: A method as described in any of the preceding aspects wherein the nozzle has an elongate transverse waist region so as to provide a generally planar or wedge-shaped output beam of condensed particles or liquid.

(47) Aspect 14: A method as described in any preceding aspect wherein the collection medium is disposed as a circumferentially circulating bath of liquid.

(48) Aspect 15: A method as described in aspect 14 wherein the liquid is circulated by mechanical means, such as a stirrer.

(49) Aspect 16: A method as described in any preceding aspect wherein the gas stream comprises reaction gas and/or a non-reactive carrier gas in addition to the vapour to be condensed.

(50) Aspect 17: A method as described in any preceding aspect wherein on exiting the nozzle the condensed droplets or particles form a first cone, the reaction gas and/or carrier gas form at least one further cone with the first cone accommodated inside the second cone and wherein a baffle means is provided around the first cone and substantially inside the further cone so as to provide a physical barrier which helps separate the carrier gas and other remaining gaseous species from the droplets or particles which pass through the baffle into the collection medium.

(51) Aspect 18: A method as described in aspect 17 wherein the baffle means comprises an axially elongate conduit, the walls of which provide separation of the first cone.

(52) Aspect 19: A method as described in aspect 18 wherein the baffle means is surrounded by a shoulder which covers at least a portion, or all of, the remaining surface of collection medium.

(53) Aspect 20: A method as described in any preceding aspect wherein the beam of droplets or particles impinges onto the collection medium at an oblique angle with respect to the medium surface.

(54) Aspect 21: A method as described in aspect 20 wherein the collection medium is disposed in a circumferentially circulating molten bath.

(55) Aspect 22: A method as described in aspect 21 wherein the bath circulation induces an inverted coaxial centrifugal cone to form in an upper surface of the bath, which cone provides an oblique surface to receive the droplet or particle beam.

(56) Aspect 23: A method as described in any of aspects 20 to 22 wherein the oblique beam impinges onto the collection medium at a location radially spaced apart from a central rotational axis of the bath, thereby assisting or causing circumferential flow of the molten bath.

(57) Aspect 24: A method as described in any preceding aspect wherein metal droplets in the beam are cooled to form solid particles before impinging on the collection medium.

(58) Aspect 25: A method as described in any preceding aspect wherein the collection medium is cooled so as to prevent liquid metal from the beam vaporizing.

(59) Aspect 26: A method as described in any preceding aspect wherein the collection medium comprises a liquid having a lower specific gravity than the condensed liquid material, which condensed liquid material is continuously or intermittently tapped from a collection medium reservoir and directed without intermediate solidification to a casting stage or alloying stage or other forming stage.

(60) Aspect 27: A method as described in any preceding aspect wherein the vaporous material to be condensed is, or comprises, magnesium.

(61) Aspect 28: Apparatus for condensing vapour such as a metal comprising a source of gas comprising the vapour, a condensing chamber fed from the vapour source by a nozzle which has an upstream converging configuration and a downstream diverging configuration so that vapour entering the nozzle accelerates into the nozzle and expands and cools on exiting the nozzle thereby inducing the vapour to condense to form a beam of liquid droplets or solid particles in the condensing chamber, and a liquid collection medium for the liquid droplets or particles, the collection medium having an exposed surface portion which is disposed so as to permit a beam of droplets or particles exiting the nozzle to impinge thereupon.

(62) Aspect 29: An apparatus as described in aspect 28 wherein the collection medium is a molten liquid.

(63) Aspect 30: An apparatus as described in aspect 28 or 29 wherein the collection medium is a salt flux.

(64) Aspect 31: An apparatus as described in any of aspects 28 to 30 wherein the collection medium is disposed in a bath.

(65) Aspect 32: An apparatus as described in any of aspects 28 to 31 wherein the collection medium is a salt flux and the salt has a specific gravity which is lower than that of the condensed droplets or particles so that in operation the condensed matter settles into a portion of the bath below the liquid.

(66) Aspect 33: An apparatus as described in any one of aspects 28 to 32 wherein means are provided for continuously moving the collection medium through a location at which the beam impinges onto the collection medium.

(67) Aspect 34: An apparatus as described in aspect 33 wherein means are provided for forming a sheet of travelling collection medium on which the beam of condensed vapour impinges.

(68) Aspect 35: An apparatus as described in aspect 34 wherein said means for forming a sheet comprises a collection medium bath which is provided with a weir or ledge over which the liquid collection medium can flow.

(69) Aspect 36: An apparatus as described in aspect 35 wherein the nozzle is disposed so as to direct the beam of droplets or particles onto a veil or stream of liquid falling under gravity from the weir.

(70) Aspect 37: An apparatus as described in any of aspect 28 to 36 wherein the nozzle is disposed so as to direct the beam of droplets or particles generally horizontally with respect to the collection medium.

(71) Aspect 38: An apparatus as described in any of aspects 35 to 37 wherein means are provided for recirculating collection medium into the bath after overflowing the weir or ledge.

(72) Aspect 39: An apparatus as described in any of aspects 28 to 38 wherein the collection medium is disposed in a bath and means are provided for circumferentially stirring the collection medium.

(73) Aspect 40: An apparatus as described in aspect 39 wherein the liquid is circulated by a mechanical means, such as a stirrer.

(74) Aspect 41: An apparatus as described in any of aspects 28 to 40 wherein the source of vapour provides reactive and/or carrier gases in addition to the vapour to be condensed.

(75) Aspect 42: An apparatus as described in aspect 41 wherein the nozzle is configured so that on exiting the nozzle the droplets or particles form a first cone and the carrier and/or reactive gases form at least one further cone, the angle of divergence of the first cone being less than an angle of divergence of the second cone, so that the first cone is inside the second cone.

(76) Aspect 43: An apparatus as described in aspect 42 wherein a baffle means is provided at a location so that it is disposed around the first cone and inside the second cone so as to provide a physical barrier which helps isolate the carrier and reactive gases from the condensed droplets or particles which pass through the baffle means into the collection medium.

(77) Aspect 44: An apparatus as described in aspect 43 wherein the baffle means is disposed around the location at which the beam of condensed particles or droplets impinges the collection medium.

(78) Aspect 45: An apparatus as described in aspect 43 or 44 wherein the baffle means comprises an axially elongate conduit, the walls of which provide separation of the first cone.

(79) Aspect 46: An apparatus as described in aspect 45 wherein the baffle means is surrounded by a shoulder region which covers at least a portion, or all of, the remaining surface of collection medium.

(80) Aspect 47: An apparatus as described in any of aspects 28 to 46 wherein the nozzle is configured and/or oriented so that the beam of droplets or particles impinges onto the collection medium at an oblique angle with respect to the medium surface.

(81) Aspect 48: An apparatus as described in aspect 47 wherein the collection medium is disposed in a bath and the obliquely oriented beam impinges onto the collection medium at a location radially spaced apart from a central rotational axis of medium in the bath, so that the momentum thereby transferred to the collection medium assists or cause circumferential flow of the collection medium in the bath.

(82) Aspect 49: An apparatus as described in any of aspects 28 to 48 wherein the nozzle is symmetric about a longitudinal rotational axis.

(83) Aspect 50: An apparatus as described claimed in any of aspects 28 to 48 wherein the nozzle is elongate in a transverse direction so that the beam of droplets or particles is provided in a generally planar or wedge-shaped form and so that the beam impinges onto the collection medium along an elongate contact region.

(84) Aspect 51: An apparatus as described in any of aspects 28 to 50 wherein means are provided for tapping the condensed liquid continuously or intermittently from the collection medium and conveying the liquid metal to a casting stage or alloying stage or other metal forming or deposition stage.

(85) Aspect 52: An apparatus as described in any of aspects 28 to 51 wherein the condensing chamber is provided with cooling means for removing heat from the collection medium.

(86) Aspect 53: An apparatus as described in any of aspects 28 to 52 wherein the liquid collection medium comprises a thin sheet of a first liquid disposed above a second liquid, the sheet being sufficiently thin to be disrupted by impinging condensed droplets or particles, to the extent that the sheet parts in a region corresponding to the impingement so as to reveal a surface of the second liquid and permit direct access of the condensed particles or droplets to the underlying second liquid for absorption therein, and wherein the thin sheet remains as a protective covering over a remaining portion of the surface of the second liquid.

(87) Aspect 54: An apparatus as described in aspect 53 wherein the first liquid comprises a salt flux.

(88) Aspect 55: An apparatus as described in aspect 53 or 54 wherein the second liquid comprises condensed vaporous material.

(89) Aspect 56: An apparatus as described in any of aspects 53 to 55 wherein the second liquid is a molten metal, such as magnesium.

(90) Aspect 57: A method or apparatus as described in any of the preceding aspects wherein the vapour comprises a metal or metallic material.

(91) Aspect 58: A method or apparatus as described in aspect 57 wherein the vapour is a metal selected from Mg, Zn, Sn, Pb, As, Sb, Bi, Si.Cd, and combinations thereof

(92) Aspect 59: A method or apparatus as described in aspect 57 or 58 wherein the source of vapour is provided by a metailothermic or carbothermic reduction apparatus and/or process.