US3660077A - Process for detinning tinned sheet iron - Google Patents

Process for detinning tinned sheet iron Download PDF

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Publication number
US3660077A
US3660077A US3660077DA US3660077A US 3660077 A US3660077 A US 3660077A US 3660077D A US3660077D A US 3660077DA US 3660077 A US3660077 A US 3660077A
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tin
detinning
plate
sheet iron
iron
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Erich Ruf
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Evonik Operations GmbH
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TH Goldschmidt AG
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    • 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.

Abstract

This invention relates to a process of detinning tin-plated sheet iron with soda lye in the presence of sodium chlorite as an oxidizing agent.

Description

United States Patent 1151 3,660,077 Ruf 1 51 May 2, 1972 [5 PROCESS FOR DETINNING TINNED 1 References Cited SHEET IRON UNITED STATES PATENTS llh'mfiwmw 2,011,305 11/1935 Smith ..75 9s 73 Assign; I,3l(),38l 7/1919 Wilcox ..75/98 2,082,487 6/1937 Frick ..75 98 [221 @1970 855,491 6/1907 Acker.... ..75/98 211 AppI.No.: 11,290 872,092 11 1907 Sperry ..75/98 Primary Examiner-Winston A. Douglas [30] Foreign Apphcatwn Pnomy Data Assistant Examiner-Peter D. Rosenberg Feb. 20, 1969 Germany ..P 19 08 503.1 Attorney-James E. Bryan 52 us. c1 ..75 98, 75/64 57 ABSTRACT 511 1111. c1. ..C22b 25/06 581 Field ofSearch ..75/64,85,98;23/89, 152 relates 3 Pmcess demmmg sheet iron with soda lye in the presence of sodium chlorite as an oxidizing agent.
3 Claims, No Drawings PROCESS FOR DETINNING TINNED SHEETIRON' This invention relates to a process fordetinning tin-plated sheet iron, i.e., tin-plate, with soda lye in the presenceof an" oxidizing agent.
In addition to the processing of tin ores, the recovery of'tin from waste tinned sheet iron plays an important role in'the production of tin metal.
For the purpose of recovering tin from tin-plate, threepric. the removal of the tin with the aid of soda lye in the presence of a suitable oxidizing agent, with subsequent' elec trolytic separation of the tin.
Various compounds have been proposed as oxidizing. 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.
In this process, only the tin which was applied to the iron galvanically or by hot-tinning as a superimposed layer during the tin-plating operation is removed as a result of the reaction of the soda lye in the presence of one of the aforementioned of sodium chlorite, if at least equimolar quantities of sodium chlorite are present, tin is oxidized from the nonvalenttstate through the bivalent to the tetravalent state, while sodium: chlorite is reduced to sodium chloride. Formed at the same time is a soluble sodium hydroxo-stannatecomplex, but the iron is not attacked thereby and can be fumished, after detinning, to the steel industry as a valuable scrap, so-called black plate. In this connection, it is of special significance that the residual tin contentof the black plate is low if 'sodium chlorite is employed as theoxidizing agent.
It is a particular advantage resulting from the use of sodium chlorite, as proposed by the presentinvention, thatdetinning. can be effected in an economical manner atelevated temperatures if equimolar sodium chlorite quantities, based on the tin, are present in excess quantities of soda lye. The excess of soda lye, however, may be maintained lower than was the case with the oxidizing agents used heretofore.
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.
When using excess quantities of soda lye and sodium chlorite, it generally suffices to perform the detinning operation with only one detinning solution; An extensive detinning.
of the tinned sheet iron is effected by virtue of the effective detinning action in the presence of sodium chlorite.
Since, in the process of the invention, it is possible to employ low lye concentrations, relatively large quantities of tin may be removed in conformity with the relatively good solubility of tin in dilute soda lye, particularly if it is ensured that the soda lye and sodium chlorite concentrations are continuously maintained in correspondence with the consumption thereof. Actually, however, the concentration of soda lye always should be so selected that excess quantities thereof are present, as compared to the lye concentration which is required as hydroxo-stannate for the complex formation of the tin.
Since the detinning of tin-plated sheet iron with soda lye in the presence of sodium chlorite is particularly effective, 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.
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.
Since, during the detinning of tin-plate with sodium chlorite-containing'soda' lye, sodium chloride is obtained as a reduction product, it is desirable to separate the tin'contained in the liquor, by means of a subsequent precipitation process, in the 'form of stannic acid and stannous hydroxide. The
separated stannic acid either may be subjected'to electrolysis,
after washing and dissolving in soda lye, with a view toward metalrecovery in the form of the stannate solution thereby obtained or, with'a view toward therecovery-of solid sodium stannate, it may be employed as sodium stannate solution for recoveringthe solid product. In principle, 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.
If sufficiently long detinning times are used, especially low residual tin contents may be achieved in the black plate obtained from the process.
The particularly good detinning of tin-plate with the aid of soda -.lye in the presence of sodium chlorite, as compared to heretofore known oxidizing agents, is further illustrated by reference to the following specific examples.
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. After 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.
B. 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 C. in a liquor containing 5 gramsofNaOl-l/l and 2.0 grams of NaNO /l.
The detinned sheet iron (black plate) has a residual tin content of 0.30 per cent by weight.
C. l50 grams of tin-plate, containing 0.79 per cent by weight Sn, are detinned, in the apparatus'of Example 1, for 20 minutes at atemperature of 100 C. in a liquor containing 5 grams of NaOl-l/l and 5 grams of NaClO ll.
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.
During the rotation of the drum, about half of the drum is immersed in the liquor.
While air is simultaneously introduced below the drum, the detinning of the tin-plate is effected during 2 hours at a temperature of 85 C. The detinned sheet iron (black plate) displays a residual tin content of 0.048 per cent by weight.
It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
What is claimed is:
1. In the process of detinning tin-plated sheet iron with excess soda lye, based upon tin, and in the presence of an oxidizing agent, 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.
2. A process according to claim 1 performed at a temperature in the range of about 50 to 200 C.
3. A process according to claim 2 in which air is passed through the reaction mixture.
l I t i

Claims (2)

  1. 2. A process according to claim 1 performed at a temperature in the range of about 50* to 200* C.
  2. 3. A process according to claim 2 in which air is passed through the reaction mixture.
US3660077D 1969-02-20 1970-02-16 Process for detinning tinned sheet iron Expired - Lifetime US3660077A (en)

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DE19691908503 DE1908503B1 (en) 1969-02-20 1969-02-20 METHOD FOR TINNING TINNED IRON SHEET

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BE (1) BE746306A (en)
CH (1) CH517829A (en)
DE (1) DE1908503B1 (en)
DK (1) DK138430B (en)
FR (1) FR2035584A5 (en)
GB (1) GB1250863A (en)
NL (1) NL144989B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272604A (en) * 1975-06-09 1981-06-09 Western Litho Plate & Supply Co. Base plate and lithographic plate prepared by sensitization thereof
US4682682A (en) * 1983-08-11 1987-07-28 Kosan Crisplant A/S Feeding conveyor for feeding articles laterally onto another conveyor, particularly a sorting conveyor
US6045686A (en) * 1997-03-18 2000-04-04 The University Of Connecticut Method and apparatus for electrochemical delacquering and detinning
CN115404484A (en) * 2022-09-24 2022-11-29 宁波金田铜业(集团)股份有限公司 Detinning agent for tin-plated copper alloy

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ZA771005B (en) * 1976-03-04 1977-12-28 British Steel Corp Removal of coatings from ferrous objects

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US855491A (en) * 1907-02-05 1907-06-04 Charles E Acker Process of detinning.
US872092A (en) * 1907-01-22 1907-11-26 Elmer A Sperry Process for detinning and recovering merchantable iron from tinplate scrap.
US1310381A (en) * 1919-07-15 wilcos
US2011305A (en) * 1934-07-31 1935-08-13 Walton S Smith Method for recovery of tin and lead from scrap mixtures containing same
US2082487A (en) * 1936-02-14 1937-06-01 Int Smelting & Refining Co Metallurgy of tin

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1310381A (en) * 1919-07-15 wilcos
US872092A (en) * 1907-01-22 1907-11-26 Elmer A Sperry Process for detinning and recovering merchantable iron from tinplate scrap.
US855491A (en) * 1907-02-05 1907-06-04 Charles E Acker Process of detinning.
US2011305A (en) * 1934-07-31 1935-08-13 Walton S Smith Method for recovery of tin and lead from scrap mixtures containing same
US2082487A (en) * 1936-02-14 1937-06-01 Int Smelting & Refining Co Metallurgy of tin

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272604A (en) * 1975-06-09 1981-06-09 Western Litho Plate & Supply Co. Base plate and lithographic plate prepared by sensitization thereof
US4682682A (en) * 1983-08-11 1987-07-28 Kosan Crisplant A/S Feeding conveyor for feeding articles laterally onto another conveyor, particularly a sorting conveyor
US6045686A (en) * 1997-03-18 2000-04-04 The University Of Connecticut Method and apparatus for electrochemical delacquering and detinning
CN115404484A (en) * 2022-09-24 2022-11-29 宁波金田铜业(集团)股份有限公司 Detinning agent for tin-plated copper alloy
CN115404484B (en) * 2022-09-24 2023-06-27 宁波金田铜业(集团)股份有限公司 De-tin agent for tin-plated copper alloy

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BE746306A (en) 1970-07-31
FR2035584A5 (en) 1970-12-18
DE1908503B1 (en) 1971-03-11
DK138430B (en) 1978-09-04
CH517829A (en) 1972-01-15
DK138430C (en) 1979-02-26
NL144989B (en) 1975-02-17
NL7002329A (en) 1970-08-24
GB1250863A (en) 1971-10-20

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