US3645867A - Method of treating cyanide-containing liquors in surface treatment installations - Google Patents

Method of treating cyanide-containing liquors in surface treatment installations Download PDF

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Publication number
US3645867A
US3645867A US834787A US3645867DA US3645867A US 3645867 A US3645867 A US 3645867A US 834787 A US834787 A US 834787A US 3645867D A US3645867D A US 3645867DA US 3645867 A US3645867 A US 3645867A
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US
United States
Prior art keywords
bath
cyanide
baths
electrolytic
water
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
US834787A
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English (en)
Inventor
Harry A H Ericson
Gustav Bertil Norstedt
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NORDNERO AG
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NORDNERO AG
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Filing date
Publication date
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/16—Regeneration of process solutions
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C02F2101/18—Cyanides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S210/00—Liquid purification or separation
    • Y10S210/902—Materials removed
    • Y10S210/903—Nitrogenous
    • Y10S210/904—-CN containing

Definitions

  • the present invention is concerned with a method of preventing the discharge of cyanide-containing liquors from chemical metal surface treating processes wherein aqueous cyanide solutions are used.
  • cyanide-containing aqueous baths are used extensively in electrolytic plating processes, such as zinc-plating, copper-plating, silver-plating etc. processes.
  • the destruction of the cyanide in the waste water from the electrolytic plant is normally carried out by decomposing it by oxidation, using chlorine as the oxidizing agent, the chlorine being supplied either as gaseous chlorine or as a hypochlorite.
  • the oxidation must be carried out at a rather high pH value. The cost will therefore be relatively high and normally amounts to three or four times the cost of the cyanide used.
  • the object of the present invention is to provide a more economical solution of the problem of disposing cyanidecontaining liquids obtained in chemical processes for surface-treatment of metals.
  • the method of the invention also provides several other advantages, inter alia a drastic reduction of the consumption of water for the process.
  • the invention is based on the principle of electrolytically decomposing the cyanide in electrolytic pretreatment baths.
  • Electrolytic oxidation has been used to some extent in practice to destroy cyanides. However, due to several practical problems the method has found only limited use. One of the great disadvantages has been high installation costs.
  • Each electrolytic plating process is normally preceded by an electrolytic cleaning of the articles in a hot alkaline bath.
  • a hot alkaline bath provides ideal conditions for an anodic decomposition of the cyanides.
  • an electrolytic decomposition of cyanides from surface treatment baths is carried out in one of the electrolytic process steps, in particular in the electrolytic cleaning baths.
  • the invention is illustrated but not limited by the following example which is diagrammatically shown on the accompanying drawing.
  • the example relates to electrolytic zinc-plating in cyanide-containing electrolytic baths.
  • the installation comprises a sequence of baths 1-12 for treating metal articles for zinc-plating. These baths have the following functions:
  • the metal articles to be treated pass through the baths mainly in the order mentioned.
  • the thin arrow lines to the right in the figure illustrate the flow of liquid to and from and between the baths as explained in detail below.
  • the baths may operate in the following manner:
  • Bath 1 is a degreasing bath containing sodium hydroxide, sodium carbonate and metasilicate, operating at a temperature of about C.
  • Bath 2 is an electrolytic degreasing bath of the same composition as bath 1.
  • the article is connected as a cathode.
  • the anode consists of graphite.
  • the bath operates at a temperature of about 80 C. and at a current density (anodic and cathodic) of about 5 to 10 amperes per sq. dm.
  • Bath 3 is also an electrolytic degreasing bath of the same composition as bath 2 and operated under similar conditions, except that the article is coupled as the anode and the cathode consists of steel.
  • a complexing agent of gluconate type is added to this bath.
  • Bath 4 is a cold water bath for rinsing the articles after they have been treated in bath 3.
  • Bath 5 is also a cold water bath for further rinsing the articles before they are treated in the plating bath.
  • the articles may also be rinsed in this bath after they have been treated in the plating bath.
  • Bath 6 is a cyanide-containing electrolytic zinc-plating bath, containing about 35 g./l. Zn, 30 g./l. NaOH and g./l. NaCN.
  • the bath operates at a temperature of not above 30 C. and at a current density of about 3 to 6 amperes per sq. dm.
  • Bath 7 is a cold water bath for rinsing the electroplated articles, which may previously have been rinsed in bath 5. Fresh water is introduced into bath 7 at a rate corresponding to the evaporation in baths 1, 2, 3, the water flowing through baths 7, 5, 4 and thence to baths 1,2,3 as indicated by the arrows in the diagram on the drawing.
  • Bath 8 is a cold water bath for further rinsing the article. From this bath, water is circulated through a basic anion exchange unit 13, where any residual zinc cyanide complexes are taken up. The ion exchange composition is regenerated, when necessary, with NaOH and the regenerate may be passed to the zinc bath 6.
  • Bath 9 is an acid pickling bath containing about 1% HNO Bath 10 is a so-called one-step ehromating bath containing about 2 g./l. alkali bichromate and fluoride and sulfate ions. Total salt content about 4 g./l.
  • Bath 11 is a cold water rinsing bath, wherein the water is circulated through a two bed (anionic and cationic) ion exchange filter unit 14, 15 so thatthe water will be completely deionized. Fresh water is introduced into this bath (through the filter unit) to compensate evaporation in bath 12.
  • Bath 12 is a final hot water rinsing bath operating at about 80 C. Evaporation is about 8 liters per sq. m. an hour, which is replaced by water taken from bath 11.
  • the improve- 1 ment which comprises passing cyanide-containing water from the rinsing baths to said electrolytic cleaning baths,

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
US834787A 1968-06-19 1969-06-19 Method of treating cyanide-containing liquors in surface treatment installations Expired - Lifetime US3645867A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE8355/68A SE321836B (en:Method) 1968-06-19 1968-06-19

Publications (1)

Publication Number Publication Date
US3645867A true US3645867A (en) 1972-02-29

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ID=20273835

Family Applications (1)

Application Number Title Priority Date Filing Date
US834787A Expired - Lifetime US3645867A (en) 1968-06-19 1969-06-19 Method of treating cyanide-containing liquors in surface treatment installations

Country Status (7)

Country Link
US (1) US3645867A (en:Method)
CH (1) CH515344A (en:Method)
DE (1) DE1931123C3 (en:Method)
FR (1) FR2013349A1 (en:Method)
GB (1) GB1226684A (en:Method)
NL (1) NL6909276A (en:Method)
SE (1) SE321836B (en:Method)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847765A (en) * 1972-12-20 1974-11-12 Mitsubishi Petrochemical Co Method for the treatment of cyanide-containing wastes
US3900377A (en) * 1973-01-02 1975-08-19 Kurt Enns Reduction of toxicity of aqueous solutions
US3970531A (en) * 1974-09-04 1976-07-20 Rockwell International Corporation Decreasing the cyanide and heavy metal content of an aqueous solution
US4024037A (en) * 1975-02-18 1977-05-17 National Research Development Corporation Oxidation of cyanides
US4145268A (en) * 1977-03-22 1979-03-20 British Columbia Research Council Method of conducting an electrolysis
US4238314A (en) * 1978-08-16 1980-12-09 Katsuhiro Okuho Continuous electrolytic treatment of circulating washings in the plating process and an apparatus therefor
US4319968A (en) * 1979-07-05 1982-03-16 Katsuhiro Okubo Electrolytically decomposing method for iron-cyanide complex

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE8005138L (sv) * 1980-07-11 1982-01-12 Sodermark Nils Erik Sett att avgifta cyanider

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847765A (en) * 1972-12-20 1974-11-12 Mitsubishi Petrochemical Co Method for the treatment of cyanide-containing wastes
US3900377A (en) * 1973-01-02 1975-08-19 Kurt Enns Reduction of toxicity of aqueous solutions
US3970531A (en) * 1974-09-04 1976-07-20 Rockwell International Corporation Decreasing the cyanide and heavy metal content of an aqueous solution
US4024037A (en) * 1975-02-18 1977-05-17 National Research Development Corporation Oxidation of cyanides
US4145268A (en) * 1977-03-22 1979-03-20 British Columbia Research Council Method of conducting an electrolysis
US4238314A (en) * 1978-08-16 1980-12-09 Katsuhiro Okuho Continuous electrolytic treatment of circulating washings in the plating process and an apparatus therefor
US4319968A (en) * 1979-07-05 1982-03-16 Katsuhiro Okubo Electrolytically decomposing method for iron-cyanide complex

Also Published As

Publication number Publication date
NL6909276A (en:Method) 1969-12-23
DE1931123C3 (de) 1980-04-30
CH515344A (de) 1971-11-15
SE321836B (en:Method) 1970-03-16
FR2013349A1 (en:Method) 1970-04-03
DE1931123A1 (de) 1970-01-02
DE1931123B2 (de) 1971-09-23
GB1226684A (en:Method) 1971-03-31

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