US3691048A - Apparatus for continuous electrolytic production of metals - Google Patents

Abstract

AN APPARATUS FOR THE CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS FROM USED BATHS MORE DENSE THAN THE METALS COMPRISING AN ANNULAR CELL FOR CONTAINING A FUSED BATH IN WHICH THE WALLS OF THE CELL CONSTITUTE THE MAIN CATHODE, AT LEAST ONE ANODE SUSPENDED IN THE CELL, MEANS TO ROTATE THE ANODE THROUGH THE ANNULAR CELL AND A SEPARATOR TO CONTINUOUSLY REMOVE FROM THE CELL THE METAL PRODUCED AT THE CATHODE. IN ITS MORE PREFERRED EMBODIMENTS, THE APPARATUS INCLUDES A CONTINUOUS UNLOADER FOR REMOVING THE METAL FROM THE SEPARATOR, A MEANS FOR CONTINUOUSLY REMOVING FROM THE BOTTOM OF THE CELL SLUDGE MORE DENSE THAN THE FUSED BATH, A CONINUOUS FEED MEANS AND A MEANS TO REMOVE FROM THE CELL GASEOUS COMPONENTS RELEASED IN THE ELECTROLYSIS PROCESS.

Description

A. J. YZNAGA Sept. 12, 1972 APPARATUS FOR CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS Filed Aug. 26, 1970 5 Sheets-Sheet l Anthony J. Yznaga INVENTOR BYQ 4 3 FIG. 8

ATTORNEY q' 1972 A. J. YZNAGA 3,691,048

I APPARATUS FOR CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS Filed Aug. 26, 1970' s Sheets-Sheet 2 Anthony J. Yznaga lNvENfOR BYWWQW ATTORNEY Sept. 12, 1912 M. YZNAGA 3,691,048

APPARATUS FOR CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS Filed Aug. 26, 1970 5 Sheets-Sheet 5 Anthony J. Yznogc! INVENTOR ATTORNEY Sept. 12, 1972 A. J. YZNAGA APPARATUS FOR CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS Filed Aug. 26, 1970 FIGS 5 Sheets-Sheet 4 Anthony J Yznaga INVENTOR BYW ATTORNEY p 1972 A. J. YZNAGA 3,691,048

APPARATUS FOR CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS Filed Aug. 26, 1970 5 Sheets-Sheet 5 Anthony J. Yznczga INVENTOR W/Q M ATTORNEY United States Patent Office Patented Sept. 12, 1972 3,691,048 APPARATUS FOR CONTINUOUS ELECTROLYTIC PRODUCTION OF METALS Anthony J. Yzuaga, 1638 Clower, San Antonio, Tex. 78201 Filed Aug. 26, 1970, Ser. No. 66,960 Int. Cl. C23b /74; C22d 3/02 US. Cl. 204-245 19 Claims ABSTRACT OF THE DISCLOSURE An apparatus for the continuous electrolytic production of metals from fused baths more dense than the metals comprising an annular cell for containing a fused bath in which the walls of the cell constitute the main cathode, at least one anode suspended in the cell, means to rotate the anode through the annular cell and a separator to continuously remove from the cell the metal produced at the cathode. In its more preferred embodiments, the apparatus includes a continuous unloader for removing the metal from the separator, a means for continuously removing from the bottom of the cell sludge more dense than the fused bath, a continuous feed means and a means to remove from the cell gaseous components released in the electrolysis process.

BACKGROUND OF THE INVENTION The present invention relates to the electrolytic production, from fused salt baths, of metals which, as released in the molten state, are lighter than the bath and more particularly to an apparatus for the production of magnesium by passage of current through a fused bath that contains magnesium in halide form.

The production of magnesium by the electrolysis of magnesium chloride as presently practiced commercially, is usually carried out as a batch-type operation in a series of electrolytic cells, into each of which a mixture of metal chloride salts such as the chloride salts of the alkaline and alkali earth metals along with magnesium chloride, in appropriate proportions, is initially charged, fused and subjected to electrolysis by passage of direct current between appropriately spaced anodes and cathodes dipping into the bath. The resulting electrolysis of the fused bath breaks down the magnesium chloride into liquid magnesium metal and chlorine gas, liberated at the cathode and anode respectively. The chlorine gas is generally drawn off through ducts penetrating the cell covers, while the molten magnesium metal is manually removed by ladling it off of the surface of the bath, the magnesium metal of course being less dense than the fused bath. It is also common practice to periodically manually rake sludge and slag, heavier than the fused bath, from the bottom of the cell in order to maintain cell efficiency at a high level.

Since in commercial operations a large number of individual cells are generally operated at the same time and since, as noted above, there is considerable manual labor involved in the production of the magnesium, labor costs on present processes are high resulting in higher cost of the magnesium produced. Moreover, the proximity of workmen to the cells can be hazardous inasmuch as the chlorine liberated is quite toxic.

SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide an improved apparatus for the production of a metal by electrolysis of a fused salt bath more dense than the metal.

It is another object of the present invention to provide an improved apparatus for the continuous production of magnesium by the electrolysis of a fused bath containing magnesium chloride.

Yet another object of the present invention is to provide an improved apparatus for the production of metals from fused baths more dense than said metals wherein said metal is continuously and automatically removed from the electrolysis cell.

Still another object of the present invention is to provide an improved apparatus for the production of metals from fused baths more dense than said metals wherein sludge which accumulates in the electrolysis cell is continuously and automatically removed.

An important object of the present invention is to provide an improved apparatus for use in a process for the production of metals from fused baths more dense than said metals which greatly reduces the amount of manual labor required to operate the process.

Another object of the present invention is to provide an improved apparatus for the electrolytic production of magnesium which reduces uneven wear on the anodes.

These and other objects of the present invention will become apparent from the drawings, the description given herein and the appended claims.

In accordance with the above-stated objects, the present invention provides, in an apparatus for the continuous production of a metal by the electrolysis of a fused bath more dense than said metal, the combination of a wall means defining an annular cell for the fused bath, the walls of the cell constituting the primary cathode, anode means suspended in the cell, means to rotate the anode means through the cell and a separating means for con tinuously removing the metal produced in the cell and which accumulates above the fused bath.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top planar view of the apparatus of the present invention.

FIG. 2 is an elevational view, partly in section, taken along the line 2--2 of FIG. 1.

FIG. 3 is an elevational view, partly in section, taken along the line 33 of FIG. 1.

FIG. 4 is an elevational view, in section, taken along the line 4-4 of FIG. 1 showing the sludge removal means of the present invention.

FIG. 5 is an elevational view, in section, taken along the line 5-5 of FIG. 1 showing the separating means of the present invention.

FIG. 6 is an enlarged elevational view, in section, taken along the line 66 of FIG. 1 showing the details of construction of the cell of the present invention.

FIG. 7 is an enlarged elevational view, in section, taken along the line 7-7 of FIG. 1 showing the assembly of the cell and the metal receiving chamber of the separating means.

FIG. 8 is an elevational view, partly in section, taken along the line 88 of FIG. 4 showing the sludge removal rake of the present invention.

FIG. 9 is an elevational view, partly in section, showing the metal unloading means of the present invention.

FIG. 10 is an elevational view, in section, taken along the line 10-10 of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring then to the figures and particularly to FIGS. 1, 2, and 3, the apparatus has an annular cell designated generally as 10 formed by inner sidewall 11, outer sidewall 12 and bottomwall 13. Inner and outer sidewalls 11 and 12, respectively, have substantially vertical upper parts and inwardly inclined lower parts joined together by arcuate shaped bottomwall 13 giving the cell a somewhat distorted V-shape when viewed in transverse crosssection, walls 11, 12, and 13 forming a generally smooth continuous wall structure. It will be appreciated that the particular cross-sectional shape of cell is not critical and is not restricted to that shown. Cell 10 is enclosed in an annular refractory-lined housing shown generally as 14 comprised of vertically extending refractory sidewalls 15 and 16 and horizontally extending refractory bottomwall 17. Walls 15, 16, and 17 are jacketed in a metallic shell consisting of sidewalls 18 and 19 and bottomwall 20. Metallic top walls 21 and 22 which adjoin the upper edge of sidewalls 12 and 11, respectively, complete housing 14. Located Within chamber 23 formed between the inside bottom of housing 14 and the bottom of cell 10 is a suitable source of heat which consists of gas burner 25 but which could be electric heating or some other form of heating. Chamber 23 is vented in a suitable fashion. While not shown, housing 14 and accordingly cell 10 are rigidly supported by a suitable framework which is electrically insulated from housing 14 and which may or may not connect to support frame 26.

Attached to the bottom surface of bottomwall 20 of housing 14 is an annular bus bar 50. Annular bus bar 50 in turn connects via vertically extending flexible connecters 51 to incoming power bus bars 52 which in turn lead to the negative side of the current supply (not shown). As will be thus seen, current from the negative side of the power supply is brought in via bus bars 52, passes via flexible connecters 51 to annular bus bar 50, is conducted via bottomwall 20 and sidewalls 18 and 19 of housing 14 to topwalls 21 and 22 and then to sidewalls 11 and 12 and bottomwall 13 of cell 10.

concentrically disposed, relative to annular cell 10, is an arbor or shaft, shown as 27, arbor 27 being rotatably mounted in a fashion hereafter described. Arbor 27 is made up of a lower section 28 and an upper section 2.9 which are separated from one another by means of a disk-shaped seal 30 sandwiched between radially outwardly extending mating flanges 31 and 32 located on the upper end of lower section 28 and the lower end of upper section 29 respectively. Bolts 33 extending through suitable registering holes in the mating flanges and nuts 33a compress flanges 31 and 32 together to thereby join sections 28 and 29. As will be hereafter described, gaseous products such as chlorine released in the electrolysis are introduced into the interior of upper section 29 of arbor 27. Seal 30 acts to prevent the escape of these gaseous components into the lower section 28 of arbor 27. Lower section 28 of arbor 27 terminates in a radially outwardly extending flange 33 which is secured by means of bolts 34 to a geared member 35. Geared member 35 has an axial extension 36 which extends downwardly into a housing 37 filled with mercury 38. A bearing and seal assembly 41 positioned between the top of housing 37 and geared member 35 serves to seal off housing 37 thereby preventing escape of mercury 38 while allowing free rotation of arbor 27. Attached to the closed end of axial extension 36 by means of bolts 39 and nuts 39a is a diskshaped member 40, disk-shaped member 40 being completely immersed in mercury 38 and rotating therein as arbor 27 rotates. Housing 37 is closed off on its bottomside by removable bottomplate 53 secured thereto by means of bolts and nuts 55a which also extend through a second pair of power bus bars 54 which lead to the positive side of the current supply (not shown). As best seen in FIGS. 2 and 3, an insulating spacer 54a electrically isolates power bus bars 52 which lead to the negative side of the current supply and power bus bars 54 which lead to the positive side of the current supply from support frame 26. Bolts 55 extend through a radially extending flange portion of housing 37 through bottom coverplate 53, power bus bars 54 and insulating spacer 54a to hold the assemblage rigidly in place. Therefore, current supplied from the positive side of the power supply via bus bars 54 is conducted through coverplate 53 to mercury 38 contained in housing 37 and thence to rotating disk 40. Since rotating disk 40 is electrically connected to the lower section 28 of arbor 27 through the axial extension 36 of geared member 35, current will then be conducted to lower section 28 of arbor 27.

A gear train consisting of upper spur gear 42 and lower worm gear 43 coaxially mounted on a shaft 44 is supported in a gear housing 47 attached to housing 37. Upper spur gear 42 meshes with geared member 35 while lower worm gear 43 is gearably engaged and driven by a shaft 48 connected by insulating coupling 91 to motor 45 suitably mounted on a motor rack 46 secured to support frame 26. It will be noted, that the presence of insulating coupling 91 between motor 45 and shaft 48 electrically isolates motor 45 from arbor 27. Thus, as motor 45 causes coupling 91 to turn, the motion is transmitted via shaft 48 and the gear train consisting of spur gear 43, worm gear 42 and shaft 49 to geared member 35 thus resulting in the rotation of arbor 27.

Attached to the lower section 28 of arbor 27 are a plurality of radially extending arms 56 which support an annular ceramic cover 57 by means of brackets 58 and 59 secured to the under face of arms 56. To allow for expansion of ceramic annular cover 57, annularly extending spaces 73 and 73a are left between the bottom surfaces of arms 56 and the top surface of cover 57. Annular cover 57 has a pair of radially spaced, vertically extending lips 60 and 61 which extend into cell 10 and which engage annular seal rings 62 and 63 respectively to thereby partially seal off cell 10. Seal rings 62 and 63, which are L-shaped when viewed in transverse crosssection, each have one leg attached to topwalls 22 and 21 respectively, the other legs extending downward into cell 10 parallel to legs 60 and 61 of annular cover 57. Although as shown in the drawings, and particularly in FIG. 6, rather large annular spaces 64 and 65 exist between lip 60 and seal ring 62 and lip 61 and seal ring 63 respectively, this is for purpose of clarity only, it being understood that in actual practice, the clearance between the seal rings 62 and 63 and the lips 60 and 61 is only suflicient to allow annular cover 57 to rotate freely.

Also extending radially from the lower section 28 of arbor 27 and on diametrically opposite sides of arbor 27 are a pair of brackets or bus bars 66 and 67 which support a pair of carbon anodes 68 and 69 respectively. By this means, anodes 68 and 69 receive electric power from arbor 27. Although only two anodes are shown for simplicity of description, it will be appreciated that in actual practice numerous anodes, as for example twenty to fifty, will be employed depending on the size of the cell. As seen in FIG. 6, anodes 68 and 69 extend vertically downward through cover 57 into cell 10 through an annular steel plate 70 secured to the bottom part of arms 56 and which serves to support bus bars 67. Seal ring or packing glands 72c surround anodes 68 and 69 and effectively prevent the escape of gaseous components from between anodes 68 and 69 and annular cover 57. Retaining rings 71 which surround anodes 68 and 69 secure glands 720 in place.

The upper section 29 of arbor 27 is rotatably mounted in journal bearings 74 and 75 which are retained in bearing support ring 76 which is rigidly attached to support frame 26 by means of upper and lower fiberglass plates 77 and 78 respectively, bolts 79 securing the fiberglass plates to support frame 26 and bearing support ring 76. As will be understood, arbor 27 is thus electrically insulated from support frame 26 since fiberglass plates 77 and 78 are non-conductors.

The upper end of upper section 29 of arbor 27 telescopes into a close fitting non-conducting sleeve 80 to form a slip coupling. Sleeve 80 can be conveniently constructed of fiberglass or some suitable plastic. Sleeve 80 has an annularly extending internal shoulder 81 in which is seated a bearing-seal assembly 82. A retaining ring 83 having a generally L-shaped appearance when viewed in transverse cross-section fits between shoulder 81 of sleeve 80 and the outside surface of upper section 29, retaining ring 83 serving to hold bearing-seal assembly 82 in place. Sleeve 80 also has a radially outward extending flange 84. Bolts 85 extend upwardly through bearing support ring 76, fiberglass plates 78 and 77 and flange 84. Nuts 86 act to urge sleeve 80 downwardly towards support frame 26 while nuts 87 act to urge retaining ring 83 upwardly against bearing-seal assembly '82 thereby allowing upper section of arbor 27 to rotate freely in sleeve 80 and yet provide an effective seal. It will thus be seen, that while sleeve 80 is retained rigidly in place, arbor 27 can rotate freely therein.

Extending through the upper end of sleeve 80 is a conduit 88 which serves as a means to continuously feed the fused bath components to the cell. As best seen in FIG. 3, conduit 88 extends substantially coaxially through sleeve 80 and upper section 29 of arbor 27 and then angles outwardly through the wall of section 29 and then downwardly through annular cover 57 and opens into cell 10. Conduit 88 is rotatably mounted in sleve 80 by means of bearing-seal assembly 89 and retaining ring 90 which holds bearing-seal assembly 89 in place. As will be observed, conduit 88 thus rotates as arbor 27 and accordingly cover 57 rotate. At its uppermost end, conduit 88 telescopes into a non-conducting sleeve 93 very similar to sleeve 80, sleeve 93 having an annularly extending internal shoulder 94 and a bearing-seal assembly 95 which rides thereon, a retaining ring 96 serving to hold bearingseal assembly 95 in place. Thus an effective slip coupling is formed between sleeve 93- and conduit '88. Sleeve 93 which is rigidly held against rotation by a suitable framework (not shown) opens into a hopper, bin or some other container for the fused bath components. As will be thus understood, the components of the fused bath enter through sleeve 93 and thence pass downwardly through conduit 88 and discharge into cell 10. The components upon entering cell are fused by heat supplied by gas burner 25 to thus form bath 101.

To allow for the release of gaseous components from cell 10, a gas conduit 97 leads from the interior of section 29 of arbor 27 to the space above the bath 101 in cell '10. As best seen in FIG. 3, gas conduit 97 is generally L-shaped having one leg which extends radially from section 29 of arbor 27 and diametrically opposite from conduit 88, the other leg, extending vertically downward through annular cover 57 opening into the space above bath 101 in cell 10. As best seen in FIGS. 2 and 3, gas leaving cell 10 passes upward through gas conduit 97 and section 29 of arbor 27 into sleeve 80 and then exits via exit duct 98 which is secured to an outlet on sleeve 80 by means of mating flanges 99 and 100 located on duct 98 and sleeve 81 respectively. Conduit 98 leads to a suitable gas recovery system (not shown).

As will be thus observed, with motor 45 energized such that arbor 27 is caused to rotate, anodes 68 and 69 will be moved through annular cell 10. At the same time, feed conduit 88 and gas conduit 97 both of which extend 7 through annular cover 57 and connect to upper section 29 of arbor 27 will also rotate with the rotation of arbor 27.

From the description given thus far, the use of the apparatus in the electrolysis of a fused bath to produce a metal lighter than the bath will be understood. The bath components are fed via conduit 88 into annular cell 10 and fused, initial heat being supplied by gas burner 25. Following the initial fusion, sufficient heat is generated by the electrolytic action to maintain the bath in the molten state. Assuming that fused bath 101 contains magnesium chloride and that it is magnesium which is sought to be produced, as anodes 68 and 69 rotate in a circular path through annular cell 10, the molten magnesium chloride is broken down into chlorine gas and liquid magnesium by the passage of electric current between anodes 68 and 69 and the cathodes which of course are the walls of cell 10. Chlorine is liberated at anodes 68 and 69 and is removed from cell 10 through gas conduit 97, section 29 of arbor 27, sleeve and conduit 98 recovered externally of the apparatus. Magnesium metal is released at the sidewalls, i.e. the cathodes of cell 10 and being less dense than the fused bath 101, floats to the top of the fused bath and collects adjacent the inner and outer walls, 11 and 12 respectively, of cell 10.

Reference is now made to FIGS. 6 and 7 for a detailed description of how the metal produced in a cell 10 is removed therefrom. A first set of vertically spaced annularly extending baffles 102 are attached at space intervals to the inner surface of inner sidewall 11. A second set of vertical spaced annularly extending baffles 103 is attached, also at spaced intervals, to the inner surface of outer sidewall 12. As best seen in FIG. 6, batiies 102 and 103 are secured to sidewalls 11 and 12 respectively by means of brackets 104 and 105. Bafiles 102 and 103 are inclined downwardly from walls 11 and 12 and are spaced from walls 11 and 12. Since baffles 102 and 103 are electrically connected to cell walls :11 and 12 by means of conducting brackets 104 and 105, bafiles 102 and 103 provide additional cathodic surface. Thus, as magnesium is liberated at the overall cathode system consisting of the walls of cell 10, and the sets of bafiles 102 and 103, the downward inclination of the bafiles directs the liberated liquid magnesium up and toward walls 11 and 12 where it collects between the vertical legs of annular seal rings 62 and 63 and sidewalls 11 and 12. As best seen in FIG. 7, a pair of gas outlets 106 and 107 project through seal rings 62 and 63, respectively, to allow any gas, such as hydrogen, liberated at the cathodes to escape from cell 10.

Located closely adjacent the uppermost part of sidewall 12 is an aperture 108, which opens into a suitably formed passageway 109 which in turn leads to the entrance duct 116 of a separating means shown generally as 1&10. As the liquid magnesium accumulates at the top of cell 10 and adjacent outer sidewall 12, it will spill through aperture 108 into passageway 109 and thence into entrance duct 116. Radially aligned with aperture 108 and substantially the same distance from the top of cell 10 is aperture 111 in inner sidewall 11. Aperture 1111 opens into a conduit 112 which is jacketed around the walls of cell 10, passing on the underside thereof, and connecting with an opening 113 which opens into passage 109. Thus, as liquid magnesium also accumulates in the upper portion of cell 10 adjacent inner sidewall 11, it will spill through aperture 111 into conduit 112 move through conduit 112 and discharge into passageway 109 via opening 113 where it joins the liquid magnesium escaping through aperture 108. The movement of anodes 68 and 69 through the cell acts to gently move the liquid magnesium around the cell where it escapes via aperture 108 and 111. The magnesium metal, shown as 114, containing small amounts of the fused bath 101, flows through passageway 109 into separating system i110. V

Separating system 1i10 comprises a walled structure which defines a chamber which can be either partially or totally enclosed. The wall structure comprises a substantially fiat vertical sidewall 115, an opposing stepped sidewall 160, a vertical end wall 118 and a semi-cylindrical end wall 161. A T-shaped partition 162 having the vertical leg of the T pointing upwardly is disposed within separating system to partition the chamber into a pump chamber 122 and a metal receiving chamber 117. The horizontal leg of T-shaped partition 162 which is spaced but closely adjacent the bottomwall 163 of separating system 1110 has an opening I124 which leads into the pump chamber 122. Metal receiving chamber 117 has a narrow neck portion formed between the upper part of the vertical leg of T-shaped partition 162, entrance duct 116 which leads into the chamber, the upper portion of vertical sidewall 115 and the upper portion of stepped sidewall 160. A pump designated generally as 119 having an impeller 120 fixedly attached to a motorized shaft 121 driven by a suitable means (not shown), is disposed within pump chamber 122. As the liquid magnesium 114 along with small amounts of the fused bath i101 enter separating system 110 through entrance duct 116, the magnesium, being lighter, tends to rise and collect in the narrow neck of receiving chamber 117 whereas the heavier fused bath 101 falls into the enlarged lower section of receiving chamber 117. Since as best seen in FIG. 5, impeller 120 of pump 119 is located within pump chamber 122 so as to take in through opening :124 material accumulating in the enlarged lower portion of chamber 117, the heavier fused bath 101 and any sludge or slag which happens to enter the separating system will be drawn into the pump chamber 122 where impeller 120 will pick it up and discharge it into a conduit 123 (see FIG. 1) which in turn opens into the bottom of annular cell 10. The overall result is that the lighter metal entering separating system 110 will rise to the top and collect in the narrow neck of negative chamber 117 whereas the heavier fused bath 101 will be returned via pump 119 to annular cell in a continuous manner.

Reference is now made to FIGS. 9 and 10 for a detailed description of the means used for unloading the magnesium metal collecting in the receiving chamber 117 of separating system 110. A dipper 125 comprising a scoop or intake section 126, a discharge or outlet section 127 and a central hollow body portion 151 joining scoop 126 and discharge section 127 is suitably affixed to a rotating shaft 128 in a manner hereafter described. Shaft 128 is journaled in bearing systems 129 and 130 which are mounted in virtual support members 131 and 132 respectively. At the opposite end of shaft i128 from where dipper 125 is connected, a geared drive wheel 133 is mechanically driven by a suitable means (not shown). On the end opposite from drive wheel 133, shaft 128 has a rigidly attached mounting wheel 134. Mounting wheel 134 is connected via electrical insulators 135 to a dipper-mounting member 136 which in turn is rigidly afiixed to dipper 125 by means of horizontally extending mounting rods 137. Thus it is seen that dipper 125 is electrically insulated from shaft 128 and its attendant drive and mounting system. Dipper 125 is disposed relative to separating system 110 such that the intake or scoop end 126 is caused to rotate into and out of the narrow neck of receiving chamber 117 as shaft i128 rotates to thereby scoop up the liquid magnesium. Also mounted within support member 131 and 132 and directly below shaft 128 is shaft 138, shaft 138 being journaled in bearings 139 and 140 carried in support members 131 and 132 respectively. Shaft 138 is mechanically linked to shaft 128 by means of a gear 141 which meshes with a like gear 142 carried on shaft 128. Thus as shaft 128 rotates, shaft 138 is caused to rotate through the geared linkage. Mounted on one end of shaft 138 is a mounting wheel 143 substantially the same as mounting wheel 134. Mounting wheel v143 is insulated from a transfer-container support member 144 by means of a series of insulators 145 very similar to insualtors 135. Support member 144 is rigidly secured by means of horizontally disposed support rods 146 to a transfer container 147. Transfer container 147 is a generally truncated cylinder, the truncated portion providing an opening 148 into container I147. Container 147 is disposed substantially vertically under dipper 125 such that as shafts 128 and 138 rotate, an opening in discharge section 127 of dipper 125 registers with opening 148 in container 147, dipper 125 and container 147 rotating in opposite directions. Disposed beneath transfer container 147 is a trough 149 having a transfer line 150 leading to a suitable collecting system (not shown).

The operation of the unloading system can be described as follows: the mechanical driving of dipper and transfer container 147 is dumping into trough 149, dipper 125 is scooping magnesium via scoop 126 from the narrow neck portion of receiving chamber -117 of separating means 110. As seen, scoop 126 of scoop 125 is connected to discharge section 127 by a hollow, truncated cone-shaped body 151, the truncated apex of coneshaped body 151 opening into scoop 126 while discharge section 127 opens into the base of cone-shaped portion 151. Thus as dipper 125 rotates such that scoop 126 moves out of contact with the metal in the neck of receiving chamber 117, the metal will flow through the cone-shaped portion 151 and be discharged through the opening of discharge section 127. Because of the synchronous movement between dipper 125 and transfer container 147, at this point opening 148 into transfer container 147 will be in register with the opening in discharge section 127 of dipper 125 such that the magnesium leaving dipper 125 will empty into transfer container 147. As the rotation of dipper 125 and transfer container 1 47 continues the opening in discharge section 127 will move out of register with opening 148 in container 147 and container 147 will rotate to a position to where opening 148 is pointing substantially downward and facing trough 149 whence it will dump the magnesium contained therein into trough 149. Magnesium will then flow from trough 149 through collecting pipe to some common collecting point. It will thus be understood that electrical contact of the magnesium metal contained in separating means 110 and that in trough 149 will be broken inasmuch as there is not an unbroken flow of magnesium from separating system 110 to trough 149 but rather an intermittent flow. Since it is common practice in the commercial production of magnesium to operate a battery of cells, it will be readily appreciated that in such a case the unloader systems, described above, would all be synchronized such that the cells remained electrically isolated, i.e. that no short circuit occurred.

Although not shown, it is preferable that separating system 110 and the means used to unload the magnesium from separating system 110 be adequately covered. As explained above, the molten magnesium has a tendency to rapidly react with water. In areas where high humidity exists, this can present a serious problem if the magnesium metal is allowed to remain in contact with the air for extended periods of time.

Reference is now made to FIGS. 1, 4 and 8 for a detailed description of the continuous sludge removal means employed in the apparatus of the present invention. As best seen in FIGS. 4 and 8, a ceramic rake 152 having a shape generally approximating the lowermost portion of cell 10 when viewed in transverse cross-section is attached by a horizontally extending arm 153 to a suitable vertically extending support member 154 which, although not shown, is rigidly supported at its topmost end in annular cover 57 in such a way as to be insulated from arbor 27. Thus, as cover 57 rotates, rake 152 will be moved around cell 10 and will tend to scrape the bottom of cell 10 carrying before it on its movement sludge, slag or any other material heavier than bath 101 which accumulated on the bottom of cell 10. Cell 10 is provided with an opening 155 in bottomwall 13 which preferably has a grating 156 laid therein. As the slag or sludge being carried by rake 152 moves across opening 155, it will drop through grating 156. Positioned below opening 155 in bottomwall 13 of cell 10 and extending generally radially outward from annular cell 10 is a tubular member 158, tubular member 158 communicating via opening 155 with the interior of cell 110. Tubular member 158 is inclined upwardly from the bottom of cell 110 and has rotatably disposed within it a screw conveyer 157, screw conveyer 157 being rotated in a direction to transfer material from the lower end of tubular member 158 to the upper end thereof. At its higher end, tubular member 158 has a downwardly facing discharge opening 159. As best seen in FIG. 4, since tubular member 158 is in open communication with cell via opening 155 in bottomwall 13, fused bath 101 will reach a level in tubular member 158 substantially the same as that in cell 10. Therefore, to prevent fused bath 101 from escaping through discharge opening 159, discharge opening 159 is located above the level reached by fused bath 101 in tubular member 158. However, the material being dumped through opening 155 by rake 152 being heavier than the components of fused bath 101 is carried upward by screw conveyer 157 through tubular member 158 and then discharged through opening 159. Thus, any sludge, 'slag or other heavy material being formed in the electrolysis process is continuously removed from cell 10 thereby maintaining the electrical efliciency of cell 10 at a high level.

While in the above description, the apparatus has been described with particular reference to the production of magnesium by the electrolysis of a fused bath containing magnesium chloride, it is to be understood that the apparatus isnot so limited. Indeed, the apparatus can be employed in the continuous electrolytic production of other metals from fused baths wherein the metal sought is less dense than the fused bath. Moreover, while the apparatus described has been shown as a single cell, it will be readily appreciated that in commercial practice a battery or series of such cells would be employed-appropriate electrical connection being made between the individual cells.

As can be seen from the foregoing, the apparatus of the present invention provides an efiicient and virtually automatic means for the continuous production of a metal from a fused bath more dense than the metal. The introduction of raw materials, the removal of the electrolysis products and the removal of by-product sludge is all accomplished in a continuous and automatic operation thus reducing the need for manual labor and increasing the overall efiiciency of the process.

I claim:

1. In an apparatus for the continuous production of a metal by the electrolysis of a fused bath more dense than said metal, the combination of wall means defining an annular cell for said fused bath,

said wall means constituting the main cathode,

at least one anode means suspended in said cell,

means for rotating said anode means through said cell in a circular path defined by said wall means, and separating means for continuously removing the metal thus produced from said cell.

2. The apparatus of claim 1 including unloader means for continuously removing the metal produced in said cell from said separating means.

3. The apparatus of claim 1 including means for continuously removing sludge more dense than said fused bath from the bottommost part of said annular cell.

4. The apparatus of claim 1 including means for continuously feeding the components of said fused bath to said annular cell.

5. The apparatus of claim 1 wherein said annular cell is covered and there are means provided for the removal of any gaseous components released in said cell by electrolysis of said fused bath.

6. The apparatus of claim 1 having a motorized arbor concentrically disposed relative to said annular cell and wherein said anode is connected to said motorized arbor by means of a radially extending bracket whereby said anode is rotated within said annular cell as said arbor rotates.

7. The apparatus of claim 6 wherein said arbor has a plurality of radially extending arms, said arms supporting an annular cover for said annular cell, whereby said cover rotates as said arbor rotates, said anode extending through said cover.

8. The apparatus of claim 7 wherein said arbor and said anode are electrically connected, and there are means 7 10 electrically connecting said arbor to a source of electric power.

9. The apparatus of claim 8 wherein said arbor is substantially hollow, the interior of said arbor and the space in said cell above said fused bath being in open communication through a gas conducting means such that gas liberated from said fused bath can escape through said gas conducting means into the interior of said arbor and thence to a gas collecting means.

10. The apparatus of claim 9 including a feed conduit for continuously feeding components of said fused bath into the upper part of said cell, a part of said feed conduit extending generally axially through said hollow arbor and then outwardly through the wall of said arbor and downwardly through said annular cover.

11. The apparatus of claim 10 including means to heat said annular cell.

12. The apparatus of claim 11 wherein said wall means comprises an inner sidewall, an outer sidewall and a bottomwall, said inner sidewall, said outer sidewall and said bottomwall being integral to thereby form a smooth wall structure.

13. The apparatus of claim 12 including a first set of downwardly inclined annularly extending baflles and a second set of downwardly inclined annularly extending baflles, said first and second set of bafiles being spaced from and attached to said outer and inner sidewalls respectively, whereby metal released from said fused bath at said inner and said outer sidewalls collects at the top of said cell and adjacent said inner and said outer sidewalls, said baflles being electrically connected to said inner and said outer sidewalls at spaced locations throughout the extent of said cell whereby said first and second set of bafiles form additional cathodes.

14. The apparatus of claim 13 wherein said separating means includes a walled structure defining a receiving chamber located adjacent said annular cell, said annular cell has an opening through said outer sidewall closely adjacent its uppermost part and there are means connecting said chamber and said opening through said outer sidewall whereby said metal collecting adjacent said outer sidewall spills through said opening into said means connecting said chamber and said opening and thence to said receiving chamber.

15. The apparatus of claim 14 wherein said inner sidewall has an opening, said opening in said inner sidewall being substantially radially aligned with said opening in said outer sdewall and being substantially the same distance from the top of said annular cell as said opening in said outer sidewall, said opening in said inner sidewall being connected to said means connecting said receiving chamber and said opening in said outer sidewall by a conduit means passing under said cell.

16. The apparatus of claim 15 wherein said separating means further includes a pump means connected to said receiving chamber and said cell for returning fused bath from the lower part of said receiving chamber to said cell.

17. The apparatus of claim 16 including mechanically driven dipper means for removing metal from the upper part of said receiving chamber, said dipper means having an inlet and an outlet disposed relative to one another such that when said dipper is out of contact with said metal in said receiving chamber and said outlet is facing substantially downward, said metal collected in said dipper means flows through said outlet and mechanically driven transfer container means having an opening therein, said dipper means and said transfer container means being disposed relative to one another and the mechanical driving of said dipper means and said transfer container means being synchronized such that said outlet in said dipper means and said opening in said transfer container means are in register with one another when said outlet is facing substantially downward whereby metal contained in said dipper means flows through said outlet and into said transfer container means, said metal in said transfer container means being dumped from said transfer container means when said outlet in said dipper means is facing substantially upward.

18. The apparatus of claim 17 including rake means disposed within said cell and connected so as to rotate as said arbor rotates, said rake means extending to the bottommost part of said cell whereby as said rake is moved through said cell, sludge accumulation is moved by said rake around said cell, and said annular cell has at least one sludge removal opening in the bottomrnost part, said sludge removal opening connecting the interior of said cell with an upwardly inclined screw conveyer means, said screw conveyer means serving to pick up at its lower end sludge falling through said sludge removal opening and discharge it from its upper end.

19. The apparatus of claim 18 wherein said sludge removal opening has a grating thereacross.

References Cited UNITED STATES PATENTS JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R.

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