Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B25/00—Obtaining tin
  • C22B25/06—Obtaining tin from scrap, especially tin scrap
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• This invention relates to a process fordetinning tin-plated sheet iron, i.e., tin-plate, with soda lye in the presenceof an" oxidizing agent.
• agents nitrite, alkali nitrate, alkali hypochlorite, alkali thiosulfate, and alkali polysulfide. This process is preferably employed in the case of relative high tin-plate quantities.
• the detinning operation preferably is performed at an elevated temperature in the range of about 50 to l 'Cl Particularly preferred is the temperature range of 80 to' 95 C.
• detinning may be performed in shorter periods of time than was possible with the oxidizing agents heretofore employed, employing the same process conditions in both cases.
• Lacquered tin plate should be delacquered in known manner prior to the detinning thereof with sodium chloritefor the removal of the tin with the aid of soda "lye in the! presence of an oxidizing agent such as, for example, .alkali containing soda lye .so that the sodium chlorite-containing soda lye solution is fully efiective.
• an oxidizing agent such as, for example, .alkali containing soda lye .so that the sodium chlorite-containing soda lye solution is fully efiective.
• lt ispreferable that either the tin-plate to be detinned have a rotarymovement imparted thereto in a-suitable vessel during the detinningoperation or that theliquor be agitated and recycled. This ensures an intimate contact of the detinning lye with the tin-plate. lf desired,*air also. may be passed through the liquor from below the tin-plateito be detinned.
• theliquors obtained during the detinning of tin-plate with sodium chlorite-containing soda lye also may be directly fed to an electrolysis operation but, in such case, a certain corrosion of the anode material. must be accepted due to the intermediate anodic formation of chlorine, and also of sodium hypochlorite and sodium chlorate, depending upon-the temperature, as a result of an immediate secondary reaction.
• EXAMPLE 1 Approximately l50 grams of tin-plated sheet iron, containing 0.79-per cent by weight Sn, are placed into a cylindrical perforated iron drum, having a capacity of about 700 ml, which is rotatably mounted in an'iron tank having a capacity ofabout 4'liters. The ratio'of the perforated surface. to the metallic surface of the iron drum is 1 2 6.8.
• the mounting of the perforated iron drum is so maintained that abouttwo-thirds of the surface thereof is immersed (during the rotation thereof at the rate of 4.5 revolutions/min.) in the liquor (about '320 ml) which is present in theiron tank.
• the liquor which contains 3' grams of NaOH/l and 0.32 gram NaClO ll, is heated, during the rotation of the perforated iron drum filled withtin-plate, to about C.
• COMPARATIVE EXPERIMENTS A 150 grams of tin-plate, containing 0.79 per cent by weight Sn, are detinned, in the apparatus of Example 1, for 20 minutes at a temperature of 80 C. in a liquor containing 3 grams of NaOl-I/ 1 and 0.53 gram of NaOCl/l.
• the detinned sheet iron (black plate) has a residual tin content'of 0.5 l per cent by weight.
• the detinned sheet iron (black plate) has a residual tin content of 0.30 per cent by weight.
• the detinned sheet iron (black plate) has a residual tin content of 0.40 per cent by weight.
• EXAMPLE 2 Approximately 200 kilograms of tin-plate, containing 0.74 per cent by weight Sn, are introduced into a hexagonal perforated iron drum, having a capacity of about 1.5 m mounted in an iron tank having a capacity of about 4 m The ratio of perforated surface to metallic surface of the hexagonal perforated iron drum is l 8 .5.
• a detinning liquor which contains 3.4 grams of NaOH/] and 032 gram of NaClOdl, is heated to 85 C. during rotation, at one revolution/min, of the perforated iron drum filled with the tin-plate.
• the detinning of the tin-plate is effected during 2 hours at a temperature of 85 C.
• the detinned sheet iron black plate
• the improvement which comprises employing sodium chlorite (NaClO as the oxidizing agent, the sodium chlorite being present in at least equimolar quantities with respect to tin.
• a process according to claim 1 performed at a temperature in the range of about 50 to 200 C.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Electrolytic Production Of Metals (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5725831

Family Applications (1)

Country Status (8)

Cited By (4)

Families Citing this family (1)

Citations (5)

• 1969
  • 1969-02-20 DE DE19691908503 patent/DE1908503B1/de not_active Withdrawn
• 1970
  • 1970-02-02 CH CH140670A patent/CH517829A/de not_active IP Right Cessation
  • 1970-02-16 US US3660077D patent/US3660077A/en not_active Expired - Lifetime
  • 1970-02-18 FR FR7005739A patent/FR2035584A5/fr not_active Expired
  • 1970-02-19 GB GB1250863D patent/GB1250863A/en not_active Expired
  • 1970-02-19 NL NL7002329A patent/NL144989B/nl unknown
  • 1970-02-19 DK DK81070A patent/DK138430B/da unknown
  • 1970-02-20 BE BE746306D patent/BE746306A/xx unknown

Patent Citations (5)

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