US940898A - Process of detinning tin-plate by means of chlorin. - Google Patents

Description

I No Drawing.

.unirnn srarns PATENT OFFICE. 7

HANS VON soiin'rz, or WETZLAR, GERMANY.

PROCE$S F DETINNING TIN-PLATE BY MEANS OF CHLOE/IN.

To all whom it may concern:

Be it known that I, HANS VON SoHi'iTz, merchantand metallurgist, citizen of Ger- 'many, subject of the King of Prussia and Emperor of Germany, residing at Philosophenweg 3, Wetzlar, in the Kingdom of Prussia and Empire of Germany, have invented certain new and useful Improvements in. Processes for Detinning Tin-Plate by Means of -Chlorin, of which the following is a full, clear, and exact description.

The treatment of tin plate material (tin plate waste and the like) with chlorin serves a double purpose, namely the obtaining of iron as free as possible from tin for the purpose of smelting, and a yield of tin, the latter in the form of thepurest possible anhy drous stannic ohlorid. I

In the application of the process as known, it has nothitherto been possible to avoid grave defects which arose mainly' owing to the factthat the moisture adhering more or less,.and also im arted by the atmospheric air, to the material to be detinned, caused the formation of solid, e; e; hydrated stannic chlorid. The result of this is that in the apparatus crusts of basic tin tetrachlorid are eposited which attack the iron or cause the formation of ferric chloridwhich then enters as an impurity into'the cliloritic tin and derange various pumping and ventilator mechanisms used in the process of chlorination, causing an abnormal increase in the power consumption of this machinery and indeed bringing the machines to a standstill after a short time of ,'working and in addition narrowingo'r choking upthe pipes. It is clear in short that this epresents a source of constant derangement in working-and also the cause of large wear and tear. Finally the stannic'chlorid crusts deposited in the apparatus are not utilizable for the mar ket, and therefore represent a permanent loss of product. A series of further defects is inherent in the use of high chlorination pressure. The pressure required for forcing I gfect yield of liquid stannic chlorid. This is the case in a higher degree in proportion as the raw material is more powerfully compressed. The more powerful the compres- Specification of Letters Patent. Patented NOV. 23, 1909. Application filed November 4, 19 08. Serial No. 4;61,081.

sion the higher the pressure of the chlorin must be, and with the more desnity will the fluid be retained inside the material.

Finally the tin plate cuttings, if after de-tinning they are subjected to special washing,

so greedily absorb the Washing liquid'andretain it with such energy that railway;

trucks loaded with v washed bundles show;

considerable'leaka'ge after runningfor 'ours..

By this meansf-notjonly' is the rusting f th'e de-tinnedcuttings-pre cisely the f i thing which it is desi'r'ableto avoid as far aspo's siblepron ot'ed,, but; injury; is done' to, the trucks and; other itieansjusetl'; for transport by corrosion ofthe-mon'p'arts; decay ofthe All these defectsareinten v by the present and, its methods application. I y

The inventive ideafisj lb sedifin ,the,

place on the avoidance oft enseofiall-zinei chanical devices 1n thecour'se';ofathechlori-i ed -to be avoided.

nation process. Further, thei'-aw material to be de-tinned is first of ,alb'co'inpletely dried before being chlorinedi 7 ill liejchlori w nation process itself'is caifriedfOnt, notbyforcing the chlorin into the substance under excessive pressure butby suctionga'vacuuni havin been carefully produced? beforehand v c n in the raw material.

' The present process is first of all charac terized by the fact that the tin plate ma-fl terial placed in a closed chamber is deprived of all moisture, and'is, before and during "chlorination, 'cooledby the natural cooling action of gases expanding from the condensed or liquefied state;

After the removal of moisture and pref liminary cooling of the material, the strongest possible vacuum .18 produced in the chlorination chamber. The chlorin is then vaporized from the liquid state, cold being thus developed, and is mixed in .the gaseous state with cold air-which may likewise expand from the liquid state andis let into the chlorination chamber, all pressure being avoided as far as possible. The chloriirand the air may suitably be introduced into the vacuum chamber through several nozzles distributed uniformly over the material in such a way that the mixture iimuedialoly and uniformly distributed over the 'cntirc contents of the receptacle or chamber. The action. of the chlorin on the tin therefore llU takes place quite uni ormly everywhere i tetrachlorid still adhering to the (l6- fi6(l which results in a like uniform distribution of the heat of combustion. The growing heat of combustion is again counteracted by the coldness of the automatically circulating gas mixture. In proportion as the tin absorbs the chlorin there is an automatic further indraft of chlorin and air, the coldness of which continually cools the gradually warming mass. ln this operation the mass of tin plate itself has a moderating -e.tl'ect.

The chlorination is ctmtplete if the entering gases havefinally destroyed the vacuum in the chlorination chamber and a condition of equilibrium has set in. It must however be observed that'during the entire process no noticeable increase of pressure above the atmospheric occurs.

The gases passing through the material carry with them the liquid stannic chlorid in Iormation and in this Way etfectively assist its liberation. The avoidance of high pressure in admitting the chlorin is further aimed at obviating any excess of chlorin in the stannic chloritl, wliichwoulcl be highly detrimental to the later use of this product.

The stannic chlorid formed is itself drawn oil from time to time in a suitable way.

Only after completion of the entire chlorination process is there a short contact of the chlorin with mechanical devices, the last residues of it being sucked out of the chlorination chamber by means of a pump and conveyed into a second chamber, where these chlorin residues are deposited in some suitable way, for instance in water.

A gentle raising of the de-tinned material to a dull glow by heating finally effects its rapid and complete liberation from the very last chemical residues, and at the same time results in the coating of the de-tinned stuff with an oxid-layer serving .as a rust protector.

As receptacles in which to carry out the chlorination, chambers in the style of coke furnaces are contemplated, in which the -ma*-" terial to be detmned is placed in bundles,

or better still, in a block filling up the entire chamber. In using such blocks the final work will consist in cutting them into suitable picces immediately after heatihg. The

adoption of these large blockshas' for itsobject to give the material a uniformly solid form without any spaces, by means of a sing]; mechanical operation, thus allowing of rapid charge and uniform chlorination without special intermediate receptacles being required.

The process thus described may then be subjected to two further modifications one of which consists in the special method of drying the tin plate-goods prior to subjecting them. to the chlorin process and the second improvement deals with the removal of the last remnants of the tin sullioiently prepared and effectively dried;

after this the de-tinning takes place in the way before described, whereupon now, for the purpose of completely removing the last residues of the tin tetrachlorid still adhering to the de-tinned plate, the latter is subjected to a special washing process in the chlorination chamber itself. This washing process is carried out in the chlorination chamber by submerging the de-ti'nned material in water once or more, or by treating the tin plate bundles for a certain length of time by means of a current or" water flowing through. A further advantage in this Washin process to be carried out in the chlorination chamber lies in the fact that the latter chamber is itself cleaned by the washing process. Again in the same chlorination chamber there finally takes place the drying of the de-tinned and Washed material inas- -much as the chamber is subjected to direct or indirect heating, or hot air, waste gases,

process proper and the like, are forced through the washed material similarly as in the above described preliminary drying process. Another ad-. vantage of the subsequent drying of the detinned and washed material in the chlorin vchamber itself, consists therein that by this means the chamber is itself also dried and is ready for charging again immediately after emptying. After washing and drying the further treatment of the completely de-tinned plate takes place, whereby these plates are compressed into the large blocks described.

What I claim is:

1. The process which consists in subjecting tin-bearing material to the action of chlorin gas, the gas being below normal temperatures.

2. The process which consists in placing the tin-bearing material in a closed chamber, producing a vacuum therein and allowin chlorin as to expand from the condense or liqu'e ed state into such chamber.

3. The process which consists in completely drying tin-bearing material and then subjecting it to the action of chlorin gas, the gas being below normal temperatures.

he process which consists in subjectin'g tin-bearing material to the act-ion of chlorin cooled below normal temperature to remove the tin, and then heating the tin material.

5. The process which consists in placing tin-bearing material in a closed chamber,

subjecting the material in said chamber to heat to dry the same, and then subjecting the material in said chamber to the action of chlorirr cooled below normal temperature.

6. The process-which consists in placing tin-bearing material in a closed chamber, subjecting the material in said chamber to heat to dry the same, then subjecting the material in.- said chamber to the action of chlorin cooledbelownormal temperature, and removing the tin tetrachlorid from said chalmben.

7 The process which consists in placing tm-bearing materlal 1n a closed chamber,

subjecting the material in said chamber to heat to dry the'same, then subjecting the material in said.- chamber to the action of chlorin cooled below normal temperature, then washing the material to remove the'tin tetrachlorid, and subsequently drying the same.

8. The process of treating tin-bearing material which consists in washing, drying and cooling such material and then subjecting it in a'closed chamber to the action of chlorin gas cooled below normal temperature.

9. The process which consists in placing a tin-bearing material in a closed chamber, producing a vacuum therein,.and allowing chlorin gas to expand into such chamber.

In witness whereof, I subscribe my signature, in presence of two witnesses.

HANS VON SOHT ITTZ.

Witnesses JEAN GRUND, CARL GRUND'.