US2815318A - Production of caustic soda - Google Patents

Production of caustic soda Download PDF

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Publication number
US2815318A
US2815318A US371286A US37128653A US2815318A US 2815318 A US2815318 A US 2815318A US 371286 A US371286 A US 371286A US 37128653 A US37128653 A US 37128653A US 2815318 A US2815318 A US 2815318A
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US
United States
Prior art keywords
mercury
amalgam
denuder
water
vessel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US371286A
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English (en)
Inventor
Shaw Harry
Mcgavin Arnold Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
US case filed in New York Southern District Court litigation Critical https://portal.unifiedpatents.com/litigation/New%20York%20Southern%20District%20Court/case/1%3A21-cv-07548 Source: District Court Jurisdiction: New York Southern District Court "Unified Patents Litigation Data" by Unified Patents is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Application granted granted Critical
Publication of US2815318A publication Critical patent/US2815318A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
    • C01D1/04—Hydroxides
    • 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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
    • C25B1/36—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in mercury cathode cells
    • C25B1/42—Decomposition of amalgams

Definitions

  • This invention relates to the production of the hydroxides of alkali metals from amalgam produced by the electrolysis of the corresponding chloride solution, using a mercury cathode and more particularly to improved methods of raising the temperature of the denuder in which the amalgam is decomposed.
  • denuder in the many descriptions which have been published of this process diferent forms of denuder have been disclosed; for example, use is made in commercial practice of a trough-like vessel, provided with catalytic bodies for promoting the reaction, slightly inclined to the horizontal, through which the amalgam and the water are made to flow.
  • Another form of denuder comprises a tower packed with catalytic bodies, over which the amalgam ows downwardly through the aqueous medium with which it is reacting.
  • water passes upwards through a tower packed with catalytic bodies, in which the packing is flooded with the amalgam which is undergoing decomposition.
  • the conditions of operation can vary within wide limits, and the highest concentration of sodium hydroxide solution which can conveniently be made can also vary within wide limits.
  • the temperature of operation can be increased by the application to the denuder, or to the materials entering it, of heat derived from some external source, but considerable additional cost is entailed in the process if steam, electricity or other fuel have to be used specifically for this purpose.
  • An alternative method of providing heat for maintaining a high temperature in the denuder is by the recovery and return of some of the heat generated by its own operation.
  • the reaction between the alkali metal and the water in the denuder is exothermic, and the heat evolved in normal operation causes the temperature of the amalgam to rise during its passage through the denuder so that the mercury leaving the denuder contains more sensible heat than the amalgam entering it.
  • the method here adopted is to heat the relatively cool amalgam as it enters the denuder by. transferring thereto heat from,
  • heat may be returned to the denuder in a very simple, ecient and economical manner by establishing a circulation of heat transfer liquid which is brought successively into direct contact with the hot mercury issuing from the denuder and the cold amalgam entering the denuder.
  • heat transfer liquid water or alkali metal hydroxide solution as the heat transfer liquid.
  • an improvement in the manufacture of alkali metal hydroxides by rst electrolysing the corresponding metal chloride using a flowing mercury cathode and thereafter reacting the alkali metal amalgam so formed with water in a separate vessel or denuder comprises a process for transferring heat from the hot mercury issuing from the denuder to the cold amalgam entering the denuder through the medium of an aqueous uid which is brought into direct heat transfer relationship with both the hot mercury issuing from the denuder and the cold amalgam entering the denuder.
  • the water after having transferred heat to the cool amalgam, is circulated to contact more hot mercury leaving the denuder and by maintaining a rapid circulation of water in this manner, a proportion of the reaction heat absorbed by the mercury is returned to the denuder by the owing amalgam.
  • the process of the present invention can be operated not only in the types of mercury cell plant in which both the mercury cathode in the electrolysis cell and the amalgam in the denuder flow over the base of trough-shaped vessels which are inclined to the horizontal, but also to plants in which the denuder has the form of a tower which may be packed with bodies promoting the reaction between the amalgam and water.
  • the amalgam issuing from the electrolytic cell is caused to ow downwardly through a heat interchanger equipped with a series of inclined planes adapted to conduct the amalgam in paths of reversing directions, countercurrent to, and4 in direct contact with, water which is forced through the heat interchanger from the bottom.
  • the heat interchanger and planes are constructed of material having little or no tendency to promote the reaction of water with amalgam. From the bottom of the heat interchanger the heated amalgam is passed to the upper end of the denuder, in which it is reacted with water in the presence of the usual cathodic bodies to produce concentrated sodium hydroxide solution.
  • the mercury which has now attained a higher temperature than the entering amalgam, is conducted into a well or. sump into which the water from the heat interchanger is also passed.
  • mercury and water are in directcontact in this well and some transfer of heat from the mercury to the water takes place.
  • the mercury and the water collecting in the sump are simultaneouslyraised through a second heat interchanger which may itself comprise a pump suitable for raising the two liquids.
  • the water and mercury may be passed countercurrent through a second heat interchanger similar in construction to the first.
  • the circulating heat transfer liquid to actuate a water lift pump for raising the mercury. During this operation, heat transfer relationship is established.
  • the mercury and water are separated and are returned respectively to the electrolytic cell and the first heat interchanger.
  • Electrolysis of sodium chloride solution takes place in the electrolysis cell 1 having a owing mercury cathode flowing downwards along the length of the cell.
  • Conventional electrical and constructural features of the cell such as the anodes and brine inlet and outlet are not indicated in the drawing.
  • Amalgam formed flows out of 1 into the counter-current heat interchanger 2 and thence to the denuder 3 where it reacts with water entering at 4 to form sodium hydroxide solution which is run off at the upper end of the denuder 3.
  • Mercury and dilute sodium hydroxide liquor from the lower end of the denuder are raised by a pump 5 driven by the pump motor 12, to the upper part of the electrolysis compartment. They flow together from the pump delivery outlet 6 into a mercury chute 7, the mercury flowing into the electrolysis cell in the normal way.
  • the water feed at 8 rst washes the mercury in the chute 7 and then ows over a Weir 9, sealed by a mercury lute at the bottom, to join the hot liquor.
  • the water feed and hot liquor are then taken off the mercury chute by means of a pipe which protrudes above the mercury ow level and thence down an external mild steel lagged pipe to the other end of the cell, the path of the circulating hot liquor being shown by 10.
  • the hot liquor then enters the heat interchanger 2 and flows counter-current to the strong amalgam from the electrolysis cell. From this heat interchanger an other external mild steel lagged pipe takes the circulating liquor back to the pump end 4 of the denuder along the line indicated by 11 the liquor being led under the main frame of the cell and fed into the denuder end box by way of the normal entrance for the water feed.
  • the heat interchanger 2 is a rectangular chest fabricated from mild steel plate and containing a number of trays alternately sloping in opposite directions, over which the strong amalgam leaving the electrolysis cell is made to ow before entering the denuder end box.
  • Hot liquor from the external feed pipe 14 enters at the bottom of the chest opposite the amalgam outlet, into a separate end compartment, from which it Hows through the rectangular opening in the partition at a level immediately below the bottom tray and into the interchanger proper. From there the hot liquor travels countercurrent to the strong amalgam, up the trays and there to the return pipe 15 through a rectangular outlet placed near the amalgam inlet.
  • a device is incorporated at the lower end of each tray to stagger the amalgamweir and so allow the hot liquor to pass counter-current upwards.
  • Mercury lutes are situated at the amlgam inlet and outlet.
  • the former is part of the normal lute 'which stops the brine in the dirt box from travelling down the amalgam chute into the denuder.
  • the latter is an additional lute which prevents the hot weak circulating liquor in the heat interchanger from mixing with the strong liquor in the denuder end box.
  • Sodium hydroxide solution formed in the denuder is run off from the upper end 13 of the denuder.
  • alkali metal hydroxide by first electrolysing an alkali metal chloride solution using a owing mercury cathode and thereafter reacting the alkali metal amalgam, so formed, with water in a separate vessel from which mercury leaves at a temperature higher than the temperature of the alkali metal amalgam entering the same, the improvement which comprises transferring heat from the hot mercury which has left said vessel to the cold amalgam entering said vessel through the medium of an aqueous fluid which is successively brought into direct heat transfer relationship with both the hot mercury which has left said vessel and the cold amalgam entering saidvessel, said water being separated from said mercury priori to said electrolyzingstage.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Metallurgy (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Treating Waste Gases (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)
US371286A 1952-07-30 1953-07-30 Production of caustic soda Expired - Lifetime US2815318A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB317877X 1952-07-30

Publications (1)

Publication Number Publication Date
US2815318A true US2815318A (en) 1957-12-03

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US371286A Expired - Lifetime US2815318A (en) 1952-07-30 1953-07-30 Production of caustic soda

Country Status (6)

Country Link
US (1) US2815318A (enrdf_load_stackoverflow)
BE (1) BE521836A (enrdf_load_stackoverflow)
CH (1) CH317877A (enrdf_load_stackoverflow)
FR (1) FR1081758A (enrdf_load_stackoverflow)
GB (1) GB732131A (enrdf_load_stackoverflow)
NL (2) NL91712C (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3311504A (en) * 1960-05-02 1967-03-28 Leesona Corp Fuel cell
US3663385A (en) * 1968-08-30 1972-05-16 Kureha Chemical Ind Co Ltd Alkali salt electrolysis by mercury process
US4199418A (en) * 1979-05-08 1980-04-22 Basf Wyandotte Corporation Mercury recovery system in electrolytic process

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB453517A (en) * 1934-03-13 1936-09-14 Krebs & Co Sa A method and apparatus for the treatment of alkali-metal amalgam obtained in electrolytic cells having mercury cathodes
US2423351A (en) * 1943-02-01 1947-07-01 Mathieson Alkali Works Inc Apparatus for amalgam decomposition
FR951159A (fr) * 1947-07-29 1949-10-18 Krebs & Co Décomposeur de l'amalgame provenant des cellules d'électrolyse pour l'obtention de lessives alcalines de haute concentration
US2551248A (en) * 1944-02-09 1951-05-01 Solvay Apparatus for the decomposition of alkali amalgams
US2631126A (en) * 1942-09-18 1953-03-10 Allied Chem & Dye Corp Mercury cathode electrolytic cell

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB453517A (en) * 1934-03-13 1936-09-14 Krebs & Co Sa A method and apparatus for the treatment of alkali-metal amalgam obtained in electrolytic cells having mercury cathodes
US2631126A (en) * 1942-09-18 1953-03-10 Allied Chem & Dye Corp Mercury cathode electrolytic cell
US2423351A (en) * 1943-02-01 1947-07-01 Mathieson Alkali Works Inc Apparatus for amalgam decomposition
US2551248A (en) * 1944-02-09 1951-05-01 Solvay Apparatus for the decomposition of alkali amalgams
FR951159A (fr) * 1947-07-29 1949-10-18 Krebs & Co Décomposeur de l'amalgame provenant des cellules d'électrolyse pour l'obtention de lessives alcalines de haute concentration

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3311504A (en) * 1960-05-02 1967-03-28 Leesona Corp Fuel cell
US3663385A (en) * 1968-08-30 1972-05-16 Kureha Chemical Ind Co Ltd Alkali salt electrolysis by mercury process
US4199418A (en) * 1979-05-08 1980-04-22 Basf Wyandotte Corporation Mercury recovery system in electrolytic process

Also Published As

Publication number Publication date
NL91712C (enrdf_load_stackoverflow)
NL180272B (nl)
GB732131A (en) 1955-06-22
CH317877A (de) 1956-12-15
FR1081758A (fr) 1954-12-22
BE521836A (enrdf_load_stackoverflow)

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