US3354072A - Electrolytic cell having vertically disposed electrodes - Google Patents

Electrolytic cell having vertically disposed electrodes Download PDF

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Publication number
US3354072A
US3354072A US295929A US29592963A US3354072A US 3354072 A US3354072 A US 3354072A US 295929 A US295929 A US 295929A US 29592963 A US29592963 A US 29592963A US 3354072 A US3354072 A US 3354072A
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United States
Prior art keywords
mercury
anode
cathode
cell
brine
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Expired - Lifetime
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US295929A
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English (en)
Inventor
Glover Sidney Thomas
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Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/042—Electrodes formed of a single material
    • C25B11/045—Mercury or amalgam

Definitions

  • This invention relates to an electrolytic cell, more particularly for the manufacture of chlorine and caustic alkali by electrolysis of brine using a moving mercury cathode.
  • an electrolytic cell for the manufacture of chlorine by e'ectrolysis of brines, having a vertically disposed cathode support provided with a flowing mercury cathode film thereon an-d an adjacent, substantially parallel anode comprising titanium having a coating of a platinum metal on the surface thereof.
  • the term vertically disposed includes not only those arrangements in which the electrodes are strictly vertical, but also those in which the electrodes are inclined to the vertical to a minor extent.
  • the angle of inclination to the vertical is preferably not very great, however, as the advantages of the vertical type of cell would then be lost or considerably reduced.
  • the angle of inclination should not be greater than about 30 to the vertical, though in some forms of apparatus less departure from the vertical than this can be allowed. It is important, for example, that the slope of the cathode surface should not cause diiculties in maintaining the mercury film and in particular should not cause the mercury to fall away from the supporting top surface. For this reason, an overhanging cathode support, if used, should usually be limited in slope to an inclination not greater than about 10 from the vertical.
  • the cathode support may be hollow or solid, but should be strong enough to withstand the pressures of brine and mercury employed and should preferably have a sufH- cient electrical conductivity for it to serve as a means for conducting the electrolyzing current to the mercury cathode.
  • Convenient materials for this purpose are metals, especially iron or mild steel.
  • a hollow cathode support has the advantage of allowing the mercury supply to be fed through it.
  • the outer surface of the cathode support should be made of a material upon which the mercury readily wets the surfaces and forms a satisfactory film, or that the outer surface of the support should be treated so as to achieve this.
  • the support is made of iron or steel, this effect can be secured by usingrmercury in which a small proportion of alkali metal is dissolved. Even a trace of sodium, for example 0.01% by weight by weight or less in the mercury will be sufficient to achieve this effect.
  • the mercury cathode film can be obtained by feeding a supply of mercury to the top of the cathode support and allowing it to flow down the cathode support.
  • a weir or other distributing device may be used to spread the mercury and secure a suitably extensive and steadily flowing film.
  • the mercury supply is most conveniently obtained by a recirculation system in which mercury which has passed through the cell is treated in conventional manner for recovery of its alkali metal content and the recovered mercury is returned to the cell.
  • the supply of mercury is preferably carried out by forming a pool of mercury in a suitable cavity at the of the cathode support, and allowing the mercury to overflow from this pool down the surface of the cathode support.
  • the mercury may be fed to the pool in anyv convenient manner, for example from an overhead supply pipe or by making the cathode support hollow and feeding the mercury upwards through it. It is preferred that the mercury feed should disturb the surface of the pool as little as possible so as to facilitate a smooth liow of mercury in the cathode film.
  • the anode structure may be made of titanium in any convenient form, providedpwith an operative anode surface consisting of a lm of a platinum metal.
  • the titanium may be the pure metal or an alloy.
  • the anode should be made of thin titanium sheet which may be supported as necessary by struts or other supporting members.
  • the sheet may be pierced, slotted, expanded, or the like or may be replaced by a woven titanium wire gauze.
  • An especially suitable material is the so-called expanded metal sheet which is made by cutting a large number of slots in a sheet of the metal .and then stretching the sheet and, optionally, rolling the resulting metal mesh to flatten it.
  • the platinum metal may be deposited on the titanium surface by known techniques, for example by electrodepo-l 0r by coating with a platinum-bear-l ing paint and tiring as in the ceramic industry.
  • the simplest possible form consists of one or more pairs of substantially parallel planar surfaces; this form, which mayconveniently .he termed a plate form, has the iadvantage Aof'being .more compact than-other forms and lso is more economical .of space.
  • the inner electrode may .be solidor hollow, but in either case itpresents an equivalent operativesurface.
  • the tubular electrodes maybe of any convenient .cross section, having straight or carved surfaces or a combination of these, as for example circular, elliptical, polygonal (for example rectangular or hexagonal.) or that of a partially or completely flattened tube.
  • This coaxial arrangement has the advantage of reducing theproblem of maintaining an adequate uniformity, continuity or spread .of mercury cathode film, by avoiding vertical edges on the cathode support surface.
  • a cathode support surface Vhaving .a cross-section which is lfree from abruptly angular .portions '(i.e. issubstantially curved throughout) is especially useful in this respect.
  • Tubular electrodes of substantially circular ⁇ cross-'section are preferred, however., as they are particularly easy to fabricate and assemble with the ⁇ desired accuracy, "and 'enable a substantially uniform interelectrode "gap and 'electrolyz'ing current distribution to be achieved.
  • a plurality of pairs of coaxially arranged pairs of tubular electrodes can be used if desired, and these can be assembled in any 'convenient spatial arrangement, for example vin honeycomb fashion.
  • Appropriate electrical connections, 'for 4example by way vof structural links, can be made lbetween the various electrode surfaces.
  • the owing mercury cathode film v may be provided on either the outer or the inner tubular 'surface of the pair; in general, I prefer that this mercury iilrn sshould be on the innerione in 'single -pair assemblies 'and on the outer ones in lmultiple ypair assemblies.
  • the -anode may be continuous or pierced by holes.
  • the lplatinum metal may be deposited lon the side -remote from the vcathode 'or on the side adjacent to the cathode.
  • the chlorine evolved may block "the rinter-electrode j'gap 'sufficiently to hinder operation of the cell, particularly'when the rate o'f brine feed is slow'or -the anode is 'n'otlouvred in order to facilitate ithe 'escape of the chlorine.
  • the brine for use in the ycells of the present invention are essentially aqueous Asolutions of alkali metal chlorides particularly sodium chloride 'and/ or potassium chloride, optionally 'containing small proportions of other compounds and may be for vexample natural brines which may have been treated to remove undesirable constituents b..-
  • the flow of brine through the cell should be directed primarily through the verticalspace defined by the anode and cathode, though it need not lne-confined to this space alone.
  • the brine .flow is preferably confined between the anode and cathode and a high brine velocity is used to prevent accumulation of chlorine in the anodecathode space and consequent interference with the electrolysis.
  • This form of cell is very suitable for the electrolysis of depleted (i.e. partially spen) brines, and lends itself to an especially simple design 'in which a tubular cell is provided with copper bands at intervals along its length for ⁇ the vsupply of electrolysing current.
  • the flow of brine may bein an upward or downward direction, 'though inthe high-speed, 'confined ow cells, this is preferably downward.
  • the anode-'cathode spacing may be determined, -as is conventional in the art, having regard for such factors as ypowerc-onsumption andthe particular cell and operating conditions employed. Usually a gap of up to 10 mm. is employed.
  • Va platinized titanium anode does not wear suicientlyduring use to make 'frequent adjustment necessary. IWhen the -c'ell of the present ⁇ invention employs vertical electrodes, ⁇ and especially ⁇ when one of the electrodes also surrounds lthe 'other electrode completely, there Vis practically ⁇ no opportunity for adjusting the interelectro'de gap once the 'cell has been assembled.
  • This problem of yadjustment isespecially diicultto solve for cells in which the anode and the 'flowing mercury cathode are substantially vertical, since any 'adjustment offtheinter-electrode gap requires Jmovementin a substantially horizontal direction.
  • Adjustment ofthe lrelative spacing of the two electrodes in a vertical vdirection then results in a -variation of 'the inter-electrode gap, the magnitude 'of Vwhich will 'depend of inter-electrode gap.
  • the means for adjustment of the relative spacing of the electrodes can be any convenient ⁇ device for providing the desired degree of movement, for example a screw-actuated device, and the position at which the upper electrode support (usually the anode support) passes through the lid or cover of the cell can be sealed by any of the conventional sealing devices to ensure that undesired leakage of chlorine and/or brine electrolyte is kept as low as possible.
  • FIGURE 1 represents a transverse vertical section of an electrolytic cell having concen tric cylindrical anode and cathode
  • FIGURE 2 represents a transverse vertical section of an electrolytic cell similar to that in FIGURE 1 but in which the brine electrolyte is confined entirely between the anode and cathode during electrolysis, and which is primarily intended to utilise a high rate of flow of electrolyte through the inter-electrode gap
  • FIGURE 3 represents a transverse vertical section of an electrolytic cell similar to that of FIGURE 1 but having coaXially arranged anode and cathode, each being in the form of a frustum of a cone
  • FIGURE 4 represents a transverse vertical section of an electrolytic cell in which the cathode support is in the form of a plate interp-osed between two sheet -anodes
  • FIGURE 5 is a diagrammatic drawing, in transverse vertical section, of a multiple cell based on the various unit cells
  • the cell comprises a base plate 1 to which are secured cylindrical cathode support 2 and outer wall 3.
  • an inlet pipe 4 is provided which passes upwardly to a barrier plate 5 which seals the whole of the inner cavity of the cathode support 2 near its upper end.
  • the mercury supply 6 is fed through this inlet pipe 4, and forms a shallow pool 7 from which the mercury overflows, across the upper edge 8 of the cathode support 2 to form a thin flowing film of mercury 9 on the outer surfaoe of the cathode support 2, and then collects in another pool 10 from which it is run otr through outlet pipe 11.
  • anode 14 Surrounding the cathode support 2 and the mercury film 9 flowing on its surface, is an anode 14 consisting of a cylinder of platinized titanium metal sheet, gauze or expanded metal sheet, held in place by current-carrying supports 13. Insulating gaskets separate these currentcarrying supports 13 from the outer wall 3 and an upper wall section 15, the assembly being clamped rigidly together by threaded rods 25 and nuts 26.
  • the upper wall section 15 is provided with a channel member 16 at its upper end, containing water 17 into which a downwardly projecting rim 18 of cover 19 dips to form a gas-tight seal.
  • the lid or cover 19' carried ya brine inlet pipe 23 and a chlorine outlet pipe 36 for the gas evolved during electrolysis.
  • the body of the cell is filled with brine 27.
  • the central cathode support is connected to the negative pole of the electrolyzing current supply by a suitable connecting lead (not shown) and the anode su-pports 13 are likewise connected to the' positive pole of the electrolyzing current supply.
  • Brine is fed in through pipe 23 in the lid 19, and then flows downwards through the cell and is electrolyzed where it passes between anode 14 and mercury film 9, and finally flows out of the cell as spent brine through an outer pipe 28 situated ⁇ at a convenient position in outer wall 2.
  • the mercury is fed in through pipe 4 and is taken out of the cell through pipe 11 as a weak alkali metal amalgam, which is then treated in an apparatus (not shown) for recovery of the alkali metal content, particularly as caustic alkali, and is then fed back to the cell for re-use.
  • Chlorine evolved during electrolysis rises through the brine in the cell and is taken ett through the pipe 36.
  • FIGURE 2 the apparatus shown is similar to that of FIGURE 1 except that the anode 14 is in this case an unperforated cylinder of which the upper end 14A extends above the upper lip S of the cathode support 2, and brine flow i's confined between ythe anode 14 and the mercury film 9.
  • the anode 14 and the cathode support 2 are conical in form and the anode 14 is carried on a current-supplying support 13 which passes out through the cover 29 of the cell through a gas-tight gland 39 and is provided with a threaded rod 31 and nuts 32 by which its position can be adjusted in a vertical direction.
  • the cell comprises a body 40 provided with a clamped cover 41, brine inlets 42 and 43 (these are alternatives, but can both be used if desired), a chlorine exit pipe 44, and at its lower end an ex'itpipe and separator 45 through which amalgam and spent brine can be drawn off through pipes 46 and 47 respectively.
  • the body 40 is filled with brine 48 and a hollow plateshaped cathode support 49 is held in place by attachment to a clamped base plate 5t).
  • Two sheets of platinized titanium (sheet or mesh) 51 are disposed on opposite sides of the cathode support and anodically connected to a source of electrolyzing current by any covenient means (not shown).
  • Mercury is fed through a pipe S2, through the hollow centre 53 of the cathode support 49, and spills out from the top of the plate and flows downwards over both sides of support 49 as a film 54 to collect at the bottom as a pool 55.
  • Electrolytic cell for the manufacture of chlorine by electrolysis of brine having a vertically disposed cathode support in the form of a frustrum of a cone provided with means for flowing a mercury cathode lm thereon, and an adjacent, substantially parallel anode comprising titanium having a coating of a platinum metal on the surface thereof.
  • Electrolytic cell as claimed in claim 1 having means for 4relative adjustment of the electrode surfaces in a vertical direction.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
US295929A 1962-07-18 1963-07-18 Electrolytic cell having vertically disposed electrodes Expired - Lifetime US3354072A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB27610/62A GB1000188A (en) 1962-07-18 1962-07-18 Moving mercury cathode electrolytic cell

Publications (1)

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US3354072A true US3354072A (en) 1967-11-21

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US (1) US3354072A (de)
AT (1) AT252276B (de)
BE (1) BE635094A (de)
CH (1) CH404612A (de)
DE (1) DE1245931B (de)
ES (1) ES290080A1 (de)
GB (1) GB1000188A (de)
MY (1) MY6600038A (de)
NL (1) NL295469A (de)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB490911A (en) * 1937-03-21 1938-08-23 Ig Farbenindustrie Ag Improvements in or relating to mercury cathodes for use in electrolysis
US2599363A (en) * 1948-06-04 1952-06-03 Ici Ltd Electrolytic cell
US2762765A (en) * 1951-06-06 1956-09-11 Hooker Electrochemical Co Methods and apparatus for electrolytic decomposition
US2876192A (en) * 1954-08-23 1959-03-03 Wurbs Alfred Amalgam producing apparatus
US3046215A (en) * 1959-05-26 1962-07-24 Paul M Sullivan Electrolytic cell with vertical mercury electrode

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB490911A (en) * 1937-03-21 1938-08-23 Ig Farbenindustrie Ag Improvements in or relating to mercury cathodes for use in electrolysis
US2599363A (en) * 1948-06-04 1952-06-03 Ici Ltd Electrolytic cell
US2762765A (en) * 1951-06-06 1956-09-11 Hooker Electrochemical Co Methods and apparatus for electrolytic decomposition
US2876192A (en) * 1954-08-23 1959-03-03 Wurbs Alfred Amalgam producing apparatus
US3046215A (en) * 1959-05-26 1962-07-24 Paul M Sullivan Electrolytic cell with vertical mercury electrode

Also Published As

Publication number Publication date
ES290080A1 (es) 1963-12-01
AT252276B (de) 1967-02-10
BE635094A (de)
MY6600038A (en) 1966-12-31
DE1245931B (de) 1967-08-03
GB1000188A (en) 1965-08-04
NL295469A (de)
CH404612A (fr) 1965-12-31

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