USRE13123E - Kabl goldschmidt and josef weber - Google Patents

Description

UNITED v onnroni oonnscnmm'r AND J'OSEF wanna, or nssnN-oN-rnn nm, GERMANY, as.

SIGZN'OBS, BY MESNE ASSIGNMENTS, TO GOLDSCHMIDT- DETINNING COMPANY, OF JERSEY CITY, NEW JERSEY, A. CORPORATION OF NEW JERSEY.

METHOD OF CLEANING OLD TINNED SHEET-IRON BOXES AND OTHER TINN ARTICLES TO BENDER THE SAME SUITABLE FOR BEING DETINNEDQ Ho Drawing. Original no. 838,028, dated November-113, 1906, Serial No. 292,662. Application for reissue filed April 8, 1908.

To all whom it may com-em:-

Be it known that we, KARL GoLnsoHtnn'r and Jesus WEBER, subjects of the King of Prussia, German Emperor, and residents of Essen-on-the-Ruhr,German Empire, have jointly invented a new and useful method of cleaning old tinned sheet-iron boxes and other tinned articles to render the same suit-- results as waste material in the manufactureof all kinds of tin-plate articles has for a long time been technically utilized by being resolved into their corn onents, tin and iron,

this has been quite di erent with the varione. kinds of articles made from tin-plate, especially old preserved-food tins, which so far have seldom been touched by the detinning industry. For more than fifty years numerous patents relating to the detinning of tin-plate scrap have been taken out, showing the lively interest taken in the problem of the utilization of tinned waste materials. These numerous patents, however, nearly exclusively dealt with the problem of separating the tin from the iron or otherwise rendering these waste materials suitable for industrial utilization.

But few patents deal with the question of preparing old tin-plate articles for the purpose of rendering same suitable for industrial utilization. Of late patents have been applied for for machinery for cutting up or perforating tin-plate'boxes. The most important question, however, of the cleaning of these tinned materials-using the wor cleaning in its widest meaninghas' only in exceptional cases formed the subject of patents or of descri tions in the technical literature. With re erence'to this we'refer to the English Patent Brindley, No. 8,693,

ofApril 15, 1902, wherein apparatus are de scribed for melting ofi' the solder and for removing from the tinned metal o paint, &c., which we call filth For the process of freeing metals from 7 tin or detmnin everythingthat is not tin or iron must considered as impurity. Thus it is not suflicient toffree the old tinned materials from only'lacquer, paper labels,

i1, grease,

Serial No. 425,973.

' the former contents, or in the form of ornamental or advertisin matter, but also the solder, of which muc is used in the manufacture of these articles, especially tin boxes, must be removed, as it contains considerable amounts of lead besides tin. This lead is naturally an impurity, since in the various detinning methods in use it combines either with the tin or the tin salts, seriously alfecting, of course, the quality of these latter, or else it remains behind in the iron.

A great hindrance to dot inning, especially in the case of old tin boxes, is a thin caoutchouc r-in which in folding the edges of the tins is aced in the fold to make the same tight. 1 cleaning methods which do not destroy this caoutchouc ring suffer from Specification of Reissued Letters Patent ReissuedJ 11116 28, 1910 I the drawback that the-fold WhlCl'l holds the caoutchofic ring is not attacked by the tin dissolving agent. Thus apart of the tin is not recovered, and this part represents not only a loss of tin, but it'also makes the iron less valuable on, account of its containing tin; The amount of tin thus lost to the operator is by no means small, considering that of the 'old tin-plate articles principally in question a very ar e portion consists of old preserved-food tms of medium and small size such as old sardine-tins, tins for various delicacies, preserves, vegetables, meat, and so onand that of these small tin boxes the folded edgeconstitutes a comparatively. large percentage. Extensive ex eriments' have shown that tins completely eed from varnish,'lacquer, paper, remainders of food, and also from the solder,-. but which still had the strip of caoutchouc in' the folds, ve after being detinned an iron containing %:0m}O.5'l30 one per cent. of tin, a quality thatis nearly unsalable, because it is useless for the main use of old iron-viz. ,,for

melting down in the Martin furnace.

. It has been shown 1) extensive trials that .to render old tinned s est-iron boxes really serviceable for detinningdpurposes the cleanin process must be divi ed in two parts 'iirst. Removal'of the adhering organic substances, not including the above-mentioned caoutohouc strips. Trials 1 have shown that the removal of these organic substances is effected rapidly and with as much completeness as is required for the purpose in View by a treatment of the old tins with caustic alkali. A dilute solution containin say, three per cent. sodium hydroxid Wll do for the urpose ifthe solution is heated. One may ocourse also work with strongerv solutions-say with ten per cent., sodium hydroxid which may be cold. For reason of economy it will of course generally be preferred to use heated and more diluted solutions. The length of the time required for this treatment with alkaline solution depends on the greatly-varying nature of the impurities from which the old tins and the like are to be freed. Five minutes will often be sufiicient. Sometimes fifteen minutes may be required. It has been found that such a washing sufiiciently destroys the organic substances and that very wellcleaned tin boxes are obtained, which after havingbeen cleaned yfrom'the adhering solution by another washing only require to be freed from the solder and the aforementioned caoutchouc strips. These latter being embedded in the air-tight folds are of course not at all or litt-leaflected by the alkaline treatment. By boiling the old tins with soda instead of caustic alkali the effect achieved is by no means equivalent. The

- treatment with soda requires much longer achieved.

' chouc.

time and much stronger solutions, and even then the purpose aimed at is frequently not Second. Removal of solder and caout- If subsequent to .the above-described treatment with caustic alkali the tinned materials be heated to a temperature only slightly above the melting-point of solderfor. example to about 350 Celsiusthe solder will be gained; but at this low temperature it Will only flow off reluctantly and show a strong tendency of further alloying with the tin. Besides at this temperature the caoutchouc strips in the folds will not be destroyed. To attain this purpose, the tinned materials must be exposed to a temperature decidedly higher; than the melting-point ofthe solder. This presents the'advantage not-only of the solder being obtained in a much more thinly-liquid state, thus preventinga part of it 'alloyin with the tin on the sheet-iron surface an forming tin-lead alloys, which it is diflicult to dissociate and which on their part again must be considered as a great hindrance to the detinning, but also of resulting in the: complete destruction of the caoutchouc' strips. The boxes may be heated for a certain length of time to the comparatively; low temperature of 400 to 500 Celsius; but a still more eflicient means has been; found to be the sudden ex osure of the tin? boxes to a temperature of mm 600 to 800 1 Celsius. In this way the solder is melted ofi in five to seven minutes,and at the same time the caoutchoucis destroyed. Of course the duration of the heating and the degree 'of temperature vary according to the size of the tin boxes treated and may also depend on the thickness of the folded edges or on the quality of the .caoutchouc to be destroyed, and the above-stated figures are only meant to give an approximate idea and not to represent the utmost limits to which one may have to go. Excessive heating must, however, be avoided, because it would cause the tin to alloy with the iron, from which alloy it would not be possible to ex-. tract the tin with the methods hitherto known and employed. If, however, the heating is done with some care,the method described will yield an excellent material, suitable in every res ect for detinning by the electrolytic as we as b a ehlorin process. The material shows c can and smooth surfaces. There is only a very small amount formerly occupied by lead adhering, and there are no more inaccessible spots on the material. At the place of the caoutchouc strip there is now a narrow channel allowing the detirining substance to circulate.

he following is a description of the course of the o eration The old tins are placed in a per orated receptacle which is provided with a lid similar to that of a wash-cylinder and then dipped into a vat with heated solution. During the di ping the receptacle containing the tinn ma terials is stirred, shaken about, v-or given a revoliible movement, so that the materials are thoroughly washed through with the lye and all organic remainders get their share After thus having reof the treatment. moved all organic'substances in this manner the c linder, with the tinned articles, is

place in a basin or reservoir filled with water wherein the materials. are washed or rinsed. The cylinder with the tinned articles is then placed in a hearth-furnace,

which may be arran ed in such manner as to have the fire at e side ofthe hearthpit, so that the cylinder suspended over the pit will be hit by the passing fire-gases from the side. In this way a-rap1d heatin' of the materials in the perforated receptace takes place. The solder flows down and is collected 0n the hearth. The fire-gases of course escape on the other side of the hearth. In this way the contents of the cylinder can rapidly be brought to the desired {em I rature. Subsequently the cylinder, wit its contents, is lifted out of the hearth and the contents poured out. This material is then ready for being detinnecl, either by the electrolytic process or by chlorin or by any other process.

As mentioned by Meredith Leitch inhis 1 American Patent No. 800,223, an important item in the process of preparing old tins for its value.

By dividing the operation of cleanin the tins into two arts'viz., washing 0 the tinned articles in an alkaline solution and subsequent heating the special advantage is insured that the solder (adhering to the tin) is recovered in a state of comparatively high purityth at is to say, free from the remainders of all kinds of impurities adhering to the tins.

Having thus fully described the nature of our invention, what we desire to secure by Letters Patent of the United States is 1. The method of cleaning sheet-iron objeots such as old tin boxes and the like preparatory to detinning, which consists in first saponifyin the adhering v filth and afterward exposing the objects to a high temperature.

2. The method of cleaning sheet-iron objects such as old tin boxes and the like preparatory to detinning which consists in first saponiff'ing the adhering filth by means of an alka ine solution and afterward exposing the objects to a high temperature.

3. The method of cleaning sheet-iron objects such as old tin boxes and the like preparatory to detinning, which consists in first treating them with a solution of sodium hydroxid' and afterward exposing them to a high temperature.

4. The method of cleaning sheet-iron objects such as old tin boxes and the like preparatory to detinning which consists in first treating them with a solution of sodium hydroxid while in a heated state and afterward exposin them to a high temperature.

5. The met 0d of cleaning sheet-iron ob jects such as old tin boxes and the like pre=. paratory to detinning, which consists in first treating them with a cleansing solution and afterward exposing them for a. certain time to a temperature of not less than 400 and not more than 800 Celsius, according to the nature of the substancesto be deteriorated.

6. The method of cleaning sheet-iron ob jects such as old .tin boxes and the like reparatory to detinning, which consists in st treating them with an alkaline solution and afterward exposing them fora certain time 'to a temperature off'not less than 400 and not more than 800 Celsius, according to the nature of the substances to be deterlorated.

7. The method of cleaning sheet-iron objects such as old tin boxes and the like, preparatory to detinning, which consists in first treating them with a solution of sodium hydroxid' and afterward exposing them for a certain time to a temperature of not less than 400 and not more than 800 00151118 according to the nature of the substances to be'deteriorated.

8. The method of cleaning sheet-iron ob jects such as old tin boxes and the like, prearatory to detinning, which consists in first treating them with a solution of sodium hydroxid while in. a heated state and afterward exposing them for a certain time to a temperature of not less than 400 and not more than 800 Celsius, according to the nature of the substances to be deteriorated.

9. The method of cleaning sheet-iron objeets such as old tin boxes and the like preparatory to detinning, which consists in first saponifying the adhering filth in a movable object container, and afterward exposing the container with its saponified ob]ects to a high fem erature.

In witness whereo we have hereunto set our hands in the resence of two witnesses.

.KA L GOLDSCHMIDT. J @SEF WEBER. Witnesses:

- L. Max WOHLGEMUTH,

E. ALDENDORFF.