DE84776C

DE84776C -

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Publication number: DE84776C
Application number: DENDAT84776D
Authority: DE

Description

KAISERLICHESIMPERIAL

PATENTAMT.PATENT OFFICE.

PATENTSCHRIFTPATENT LETTERING

KLASSE 40: Hüttenwesen.CLASS 40: Metallurgy.

EUGEN KOTZUR in BERLIN. Entzinniingsverfahren. EUGEN KOTZUR in BERLIN. Detinning process.

Patentirt im Deutschen Reiche vom 6. Januar 1895 ab.Patented in the German Empire on January 6, 1895.

Die Neuheit des vorliegenden Zinngewinnungsverfahrens aus Weifsblechabfällen besteht darin, dais die Zinngewinnung in zwei Phasen stattfindet, und zwar wird der gröfste Theil desselben durch einen elektrolytischen Procefs und nur ein kleiner Rest auf chemischem Wege gewonnen. Bei dieser Zweiphasigkeit des Verfahrens erreicht man den nicht zu unterschätzenden Vortheil, dafs die zweite Phase des Verfahrens, die Regenerirung des Elektrolyten, für die erste Phase des Verfahrens im Gefolge hat.The novelty of the present tin production process from tinplate waste is that that the production of tin takes place in two phases, and indeed most of it becomes the same obtained by an electrolytic process and only a small remainder chemically. With this two-phase The advantage of the process, which should not be underestimated, is that of the second phase of the process, the regeneration of the electrolyte, for the first phase of the process in Has entourage.

Die derzeitigen elektrolytischen Methoden zur Entzinnung von Weifsblechabfällen leiden an dem Uebelstand, dafs die Elektrolyte sehr schnell unbrauchbar werden. Die Säuren, Schwefelsäure und Salzsäure, sättigen sich sehr rasch mit Eisen, verursachen dann hohe Spannungen in den Bädern, lösen an der Anode das Zinn nicht mehr oder nur mangelhaft und bewirken an der Kathode den Niederschlag unreinen Zinns, indem sich basische Salze absetzen oder bei höherer Stromdichte gar Eisen mit ausfällt. Man mufs daher die Elektrolyte regelmäfsig abstofsen und durch häufige Zugabe frischer . Säure die Bäder in Ordnung halten.The current electrolytic methods for detinning tinplate waste suffer the problem that the electrolytes very quickly become unusable. The acids Sulfuric acid and hydrochloric acid, saturate themselves very quickly with iron, then cause high levels Tensions in the baths no longer dissolve the tin at the anode, or only inadequately and cause impure tin to precipitate on the cathode by forming basic Deposits salts or, with a higher current density, iron also precipitates. One must therefore Regularly dispose of electrolytes and, through frequent addition, fresher. Acid the baths in Keep order.

Noch gröfser sind die Uebelstände beim Arbeiten mit alkalischen Lösungen. Diese Elektrolyte enthalten stets neben kaustischem Alkali entweder von Anfang an zugesetztes zinnsaures Natrium oder solches, welches sich im Lauf der Stromarbeit gebildet hat. Durch die Einwirkung der Kohlensäure der Luft geht dies kaustische Natrium sehr schnell in kohlensaures Natrium über, welches für den Zweck der Entzinnung werthlos ist. Mit der Zunahme des Gehaltes an zinnsaurem und kohlensaurem Natrium und der Abnahme an kaustischem Natrium steigt nicht nur die Spannung im Bade, sondern es wird auch schliefslich an der Anode immer mangelhafter gelöst. Die Bäder entwickeln Sauerstoff und Wasserstoff, d. h. die Zinnausbeute wird immer geringer. Das Eisen wird mangelhaft entzinnt und ist für hüttenmännische Zwecke nicht mehr verwendbar, kurz es mufs ein Theil des Elektrolyts abgestofsen und durch kaustisches Alkali ersetzt werden. Mit dem Elektrolyt geht gleichzeitig ein Theil des Zinns in Form von zinnsaurem Natrium verloren.The inconveniences are still greater when working with alkaline solutions. These electrolytes In addition to caustic alkali, they always contain tin acid added from the start Sodium or something that has formed in the course of electricity work. Through the Exposure to the carbonic acid of the air changes this caustic sodium very quickly into carbonic acid Sodium, which is worthless for the purpose of detinning. With the increase the content of tinate and carbonate of sodium and the decrease in caustic Sodium not only increases the tension in the bath, but it also eventually increases in the bath Anode dissolved more and more inadequately. The baths develop oxygen and hydrogen, i. H. the tin yield is getting lower. The iron is deficiently tinned and is for Metallurgical purposes can no longer be used; in short, part of the electrolyte must be used repelled and replaced by caustic alkali. With the electrolyte goes at the same time some of the tin is lost in the form of sodium stannous.

Der Vorschlag des Dr. W. Borchers, durch Eindampfen zur Trockene Präparirsalz aus den Lösungen herzustellen, ist in der Praxis unausführbar, weil mit den Weifsblechabfällen stets eine Menge Substanzen, wie Lack, Fett, Schmutz u. s. w., dem kaustischen Elektrolyt zugeführt werden, welche die Lösung so stark verunreinigen , dafs sie braun gefärbt ist und ein dunkles, total verunreinigtes, nicht klar lösliches Präparirsalz giebt; auch durch Glühen mit oxydirenden Substanzen, wie Salpeter, ist das Product nicht weifs und löslich zu erhalten. Aufserdem ist es so stark mit kohlensaurem Natrium und eventuell Kochsalz oder anderen im Bade vorhandenen Salzen vermischt, dafs es in der Färberei oder Druckerei, dem einzigen Verwendungsfelde, nicht Absatz finden kann.The suggestion of Dr. W. Borchers, by evaporation to dryness from the Producing solutions is impracticable in practice, because always with the white sheet metal waste a lot of substances such as paint, grease, dirt, etc., are added to the caustic electrolyte which contaminate the solution so badly that it is brown in color and becomes a gives dark, totally contaminated, not clearly soluble preparation salt; also by glow with oxidizing substances, such as saltpetre, the product cannot be obtained white and soluble. It is also so strong with carbonate of sodium and possibly table salt or other The salts present in the bath are mixed, so that they are the only ones in the dye-works or printing-works Fields of use, cannot find sales.

Man kann nun zwar theilweise die Luft abhalten, wie das William Beatson in der Beschreibung seines englischen Patentes Nr. 12200 A. D. 1890 andeutet, indem man die Bäder zu-It is true that one can partially keep the air out, as William Beatson did in the Description of his English patent no. 12200 A.D. 1890 suggests by closing the baths

Claims

covers and only for emptying the 'de-tinned schnitzel and for filling with new material opens. But with this one only partially achieves the desired purpose and above all the work becomes an extraordinarily dangerous one. It is never against the end of the operation to avoid the formation of hydrogen and oxygen entirely, immediately Does not want to remove waste from the bath half tinned, so that an explosive gas mixture can easily be found arises, which is created by an excellent piece of white sheet metal, which forms a short circuit, can be ignited. '

The chemical process is formed by electrolytic baths carried out with alkaline baths Procefs a necessary and beneficial complement both in terms of complete Extraction of the tin from the de-tinned material, as in terms of maintenance favorable conditions, d. H. Creating a conductive electrolyte for the electrolytic proces.

Thus, by dividing the process into two phases, the second has a double effect Part, namely of the chemical process; it ensures the full extraction of the tin and regenerates the electrolyte for the first part of the process.

The procedure is as follows:

Man. puts the materials to be detinned in an electrolytic bath as an anode; the The bath electrolyte contains caustic alkali. If one conducts the current through it, it becomes Detinning of the material is going on with the formation of tin oxide on the anode, which dissolves with caustic alkali and is largely deposited on the cathode as tin, over 90 pct., while a few percent of the stannous acid alkali remain in the bath and become to enrich in the same; Finally, due to the receding of the bath, there is a lack of caustic Alkali, both by this stannous sodium and by the action of the air, which forms carbonic alkali. This The lack of caustic alkali causes the tin oxide to form on the anode no longer resolves. The tension in the bath rises and no solution occurs Tin on the anode more because it is covered with tin oxide. To prevent this, a part of the electrolyte is removed in time and subjected to a chemical one Procefs, which remove the tin oxide from the lye, and caustic alkali creates anew. This chemical process can be carried out either according to a) or b).

a) The tin oxide is precipitated from the electrolyte according to patent specification No. 21628 Carbonic acid off; it. Forms carbonate of sodium from the stannous sodium, while the tin oxyhydrate is deposited in a pure white color even from very brown colored solutions, since the organic substances which color the solutions are replaced by the carbonic acid from the alkaline ones Solution will not be precipitated.

As is well known, tin oxyhydrate is used, but the resulting lye is used essentially contains carbonate of sodium, is causticized by lime in a known manner.

b) The second method is based on using the electrolyte according to Patent No. 54136 boils with lime and thus converts the stannic acid sodium into stannic acid lime and caustic sodium, according to the equation:

Na ₀ Sn O ₃ + Ca (OH) ₁ , = CqSnO ₃ + 2NaO H.

The caustic sodium goes back into the electrolytic process, while the Tin can be obtained from the stannous lime by metallurgical or chemical means.

Pateντ claim:

A detinning process, characterized in that detinning is electrolytic with the use of caustic, alkaline baths, the greater part of the tin is obtained electrolytically, but the remainder of the The tin in solution is chemically obtained with the by-product of alkali will.