US3464903A - Method of adjusting individual anodes in a mercury cathode cell - Google Patents

Method of adjusting individual anodes in a mercury cathode cell Download PDF

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Publication number
US3464903A
US3464903A US472907A US3464903DA US3464903A US 3464903 A US3464903 A US 3464903A US 472907 A US472907 A US 472907A US 3464903D A US3464903D A US 3464903DA US 3464903 A US3464903 A US 3464903A
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Prior art keywords
anode
cell
cathode
gap
anodes
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Expired - Lifetime
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US472907A
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English (en)
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John Peter Hodson Shaw
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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
    • C25B15/00—Operating or servicing cells
    • C25B15/04—Regulation of the inter-electrode distance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/045—Circuits

Definitions

  • the present invention relates to a process of electrolysis, and more particularly to an improved process for the electrolysis of alkali metal chloride solution in a cell having a flowing mercury cathode.
  • the anodes may for instance consist of graphite plates or of sheet titanium supports having a platinum metal anode coating, with their underfaces substantially parallel to the mercury cathode. If the gap between an anode and the cathode is too narrow, the current efficiency of electrolysis will be reduced excessively by reaction of chlorine with sodium in the cathode amalgam. Shorting may also occur, causing overheating of the anode and, in the case of titanium-supported anodes, causing severe damage to the platinum-metal coating.
  • the gap between the anode and the cathode of a mercury cell producing chlorine by the electrolysis of alkali metal chloride solution can be adjusted with great accuracy and reproducibility by measuring the electrical resistance or conductance of the electrolyte gap between the anode and the cathode of the Working cell and setting the position of the anode with respect to the cathode so that this resistance or conductance is brought to a predetermined value.
  • a multianode mercury cell can be operated at surprisingly high energy efficiency by adjusting the electrolyte gap between each anode and the cathode so that these gaps all have the same electrical resistance or conductance.
  • a method of setting an anode in accurately-spaced relationship to the cathode surface of the mercury cathode cell producing chlorine by electrolysis of alkali metal chloride solution comprises measuring the electrical conductance across the electrolyte gap between the said anode and the cathode of the working cell and adjusting the spacing of the anode from the cathode surface so that the said conductance is brought to a predetermined value.
  • the present invention provides a method of operating at high energy efficiency a multianode mercury cathode cell producing chlorine by electrolysis of alkali metal chloride solution which comprises setting each anode in accurately-spaced relationship to the cathode surface by the method described in the preceding paragraph, the predetermined electrolyte gap conductance employed being the same for each anode.
  • the present invention provides a method of adjusting an electrolyte gap accurately by setting to a selected conductance value and it is obviously desirable to work the cell at the conductance corresponding to the optimum gap, nevertheless the invention is most valuable in enabling all the anodes in a multi-anode cell to be set to substantially the same electrolyte gap whether or not this gap is exactly the optimum, since such uniform setting has been found to be the most important factor in obtaining the best current distribution between the anodes and hence a high current efiiciency.
  • the conductivity of the aqueous electrolyte in the anode-cathode gap of a working cell varies to some extent with electrolyte concentration, temperature and the effect of the chlorine gas bubble film, the last-mentioned effect being largely a function of anode design. Furthermore it can be determined by varying the gap between the anodes and the cathode of a working cell that the optimum gap with respect to energy and current efiiciency and hence the resistance of the gap varies somewhat inversely with respect to electrolysing current density. The conductance to which the anode-cathode gap or gaps should be set for best results will therefore depend on these factors collectively.
  • the optimum conductance lies in the range 5,00018,000 ohms per m (5,00018,000 reciprocal ohms per m of cathode surface, where the said cathode surface is calculated as the cathode surface associated with each anode by dividing the total cathode surface by the number of anodes in the cell.
  • the optimum electrolyte gap conductance was found to average 7,000 mho/m. of cathode surface at a cathodic current density of 3 ka./m.
  • the probe attached to the anode plate may 'be omitted and the voltage measurement may be made between the cell baseplate and a point on the anode connector outside the cell, and the ohmic potential drop due to the electrolysing current flowing in the anode connector structure may be subtracted from this measured value in order to arrive at the voltage drop across the electrolyte gap.
  • a very suitable instrumcnt for the purpose is the resistance measuring ap- .4 paratus of our copending application No. 32,850/ 64. As described in the specification of the said copending application, arrangements can be made with this instrument to subtract automatically from an anode-cathode probe voltage a voltage equal tothe sum of the reversible cell potential and the chlorine overvoltage.
  • the instrument then reads resistance of the anode-cathode gap directly by dividing the residual voltage by a factor proportional to the current flowing through the bus-bar to the individual anode. It will be understood that the measuring scale of the instrument may be calibrated in the reciprocals of resistance so as to read conductance directly if desired.
  • 1 is the baseplate, which is connected to the negative pole of the electrolysing current source
  • 2 is a side wall
  • 3 is the cover of the cell.
  • the junctions between these parts are sealed by gaskets 4.
  • 5 is a flowing mercury cathode in contact with the metal baseplate.
  • the cell will usually have several anodes, which are required to be equally spaced from the cathode, but in the part cell shown in the drawing only one of the anodes is shown by way of illustration.
  • the anode assembly comprises a main anode block 6, suitably of graphite, a graphite shaft or tup 7 screwed into the anode block and passing through the cell cover, and a copper core 8, which is force-fitted into a bore in the upper end of the shaft 7 and to which an electrical connection is made from the positive pole of the electrolysing current source by copper bus-bar 9, which is attached to the threaded upper end of copper core 8 by means of nut 10 and washers 11.
  • a flanged screw adjuster 12 rests on the cell cover and surrounds the shaft 7.
  • the screw adjuster is provided with an internal screw thread which engages a screw thread 13 on the upper end of the shaft 7 and thereby supports the anode assembly.
  • Flanged retainers 14 are held on the cell cover by bolts 15 embedded in the cell cover and nuts 16 so that the flanges of the retainers engage the flange of the screw adjuster 12 and locate the ad uster correctly on the cell cover.
  • the anode assembly can be raised or lowered so as to obtain a desired gap between the lower face of the anode block 6 and the upper surface of the flowing mercury cathode 5.
  • 17 is a bung of resilient material closing a hole in the cell cover through which passes a titanium wire 18 which makes electrical connection with the upper surface of anode block 6 through a titanium terminal screw 19.
  • a second terminal connection is provided on the edge of the baseplate nearest the anode and opposite the position marked X on the drawing.
  • the potential difference between the two terminals can be related to the current flowing to the anode through bus-bar 9, using for example the instrument of the said copending applicatron and allowing for the known reversible cell voltage and the chlorine overvoltage, so that the conductance of the electrolyte gap is measured.
  • a method of operating at high energy efiiciency a multi-anode mercury cathode cell producing chlorine by electrolysis of alkali metal chloride solution which comprises measuring the electrical conductace across the electrolyte gap between each anode and the cathode of the working cell by measuring the voltage drop between a probe attached to the anode plate and the cathodic baseplate of the cell, subtracting from this measurement the calculated value of the reversible cell potential between anode and cathode and the chlorine overvoltage and relating the residual voltage drop thereby obtained to the measured current flowing to the anode and adjusting the spacing of each anode from the cathode surface so that the said conductance is brought to a predetermined value.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
US472907A 1964-08-12 1965-07-19 Method of adjusting individual anodes in a mercury cathode cell Expired - Lifetime US3464903A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB32849/64A GB1088162A (en) 1964-08-12 1964-08-12 Mercury cathode electrolytic cells

Publications (1)

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US3464903A true US3464903A (en) 1969-09-02

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US472907A Expired - Lifetime US3464903A (en) 1964-08-12 1965-07-19 Method of adjusting individual anodes in a mercury cathode cell

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US (1) US3464903A (enrdf_load_html_response)
GB (2) GB1088162A (enrdf_load_html_response)
NL (1) NL6510362A (enrdf_load_html_response)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004989A (en) * 1974-04-18 1977-01-25 Olin Corporation Method for automatic adjustment of anodes based upon current density and current

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3052618A (en) * 1957-02-09 1962-09-04 Solvay Apparatus for automatic regulation, during working, of the distance between the electrodes of electrolytic cells having a movable mercury cathode
US3268427A (en) * 1962-08-30 1966-08-23 Uhde Gmbh Friedrich Electrolysis of alkaline chloride solutions
US3329592A (en) * 1963-08-30 1967-07-04 Reynolds Metals Co Method of and apparatus for controlling aluminum reduction pots

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3052618A (en) * 1957-02-09 1962-09-04 Solvay Apparatus for automatic regulation, during working, of the distance between the electrodes of electrolytic cells having a movable mercury cathode
US3268427A (en) * 1962-08-30 1966-08-23 Uhde Gmbh Friedrich Electrolysis of alkaline chloride solutions
US3329592A (en) * 1963-08-30 1967-07-04 Reynolds Metals Co Method of and apparatus for controlling aluminum reduction pots

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004989A (en) * 1974-04-18 1977-01-25 Olin Corporation Method for automatic adjustment of anodes based upon current density and current

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NL6510362A (enrdf_load_html_response) 1966-02-14
GB1088162A (en) 1967-10-25
GB1146466A (en) 1969-03-26

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