US2214611A - Apparatus for treating metals - Google Patents

Description

Sept. 10, 1940. E. H. GREENBERG APPARATUS FOR TREATING METALS 3 Sheets-Sheet 1 Filed Dec.

. INVENTOR 5/020 1 're nbf? BY 1 I haul MK /V ATTORNEY Sept. 10, 1940.

E. H. GREENBERG APPARATUS FOR TREATING METALS Filed Dec. 16, 1956 3 Sheets-Sheet 2 INVENTOR 70121 H Greenhy ATTOR EY Sept. 10, 1940.-

E. H. GREENBERG APPARATUS FOR TREATING METALS a Sheets-Sheet 3 Filed Dec. 16, 1936 /M a i a W 5 Patented Sept. '10, 194a UNITED STATES.

PATENT OFFICE 9 Claims.

This invention relates to 'an apparatus and process for treating metals and particularly for detinning lead alloys. It is especially concerned with such apparatus and process for the production and removal of tin as volatfle tin tetrachloride from alloys or mixtures containing lead and tin.

It is known that chlorine gas will react with lead and tin to form lead chloride and stannous chloride. 'Stannous chloride in the presence of more chlorine is changed into stannic chloride which is volatile at a known elevated temperature and by heating to that temperature should theoretically be removable from the lead chloride which is not volatile when heated to that. temperature. Apparatuses and processes have been heretofore proposed utilizing this principle for separation of tin, but various diiliculties have been encountered due in part to lack of appreciation of the proper conditions for operation and 1 in part to the highly corrosive and poisonous nature of chlorine gas, particularly at high-temperatures. The use of chlorine on mixtures of alloys containing lead and tin at low temperatures where the metal is in granular but not melted state, is not practical because the chlorine attacks the exterior of the granules but the chlorides formed then prevent contact of the chlorine with the metals underneath. Operation at higher temperatures has not been practical prior to the present invention, so far as I am aware, because of difflculties in providing a suitable apparatusand process that could be operated ecor nomically and efliciently to produce the desired results.

. The principal object of my invention accordingly is to overcome at least some of the dimculties heretofore recognized and to provide a practical apparatus and process for the desired removal of tin from mixtures or alloys containing lead and tin with or without other metals.

The invention accordingly comprises the novel apparatus and combinations thereof, as well as a the novel processes and steps of processes which may be carried out in such apparatus, specific Fig. 1 is a diagrammatic elevation partly in section of the apparatus;

(class-s4) Fig. 2 is an enlarged detail section of the reaction chamber; Fig. 3 is a cross-section thereof on the line 3-3 of Fig.2; e

Fig. 4 isan enlarged detail view of one ofthe plurality of chlorine pipes passing from a bustle pipe into the reaction chamber;

Fig. 5 is a diagrammatic view partly in section of a modification of the kettle and reaction chambers in which two kettles are employed provided.

so that a constant level of molten metal may be maintained easily in the kettle in which the reaction chamber is placed;

Fig. 6 is a diagrammatic elevation partly in section of another'modification of the apparatus showing three kettles permitting continuous operation of the process; and

Fig. 7 is a' diagrammatic elevation partly in section showing a modification of the apparatus shown in Fig. 5 and in place of the second kettle employing a furnace with a bay in which the pump works.

Because of the corrosive and poisonous character of chlorine, especially at temperatures of 1000-1050 F. at which I prefer to practice the process of the invention as described below, I have shown in the drawings an apparatus in which the chlorine, while combining with the tin, operates in a comparatively restricted area. In that area the apparatus is preferably lined with a chlorine-resistant material which is described and claimed in my copending application Ser. No. 120,877, filed January 16, 1937. In addition the chlorine is confined within this area so that its escape beyondit in any substantial quantity is prevented. If small quantities pass off with the volatilized tin chloride they are collected by washing, as later described. J

Referring now to the drawings and particularly to Figs. 1 to 4, the numeral I designates an open steel kettle supported in a; kettle setting 2. 3 is a burner which may be operated by oil or gas and passes through a port in the kettle setting in order to heat the kettle I. 4 is a framework of channel iron or similar structure extending across the top of the kettle to support, the reaction chamber and other apparatus hereinafter described. -5 is an electric motor mounted on the channel iron 4 and serving to operate the pump 6. This pump per se is described and claimed in my copending application Ser. No. 118,704, filed January 2, 1937. The pump is connected by pipe I with 'a cylindrical reaction chamber open at the bottom, which has an outer shell of cast iron 8 lined on the inside with feed pipes It.

clay brick 9 (see Figs. 2 and 3). Inside the clay brick 9 is a special concrete layer it adapted to withstand the corrosive effects of chlorine at the temperatures above mentioned. This concrete by the framework t and when in operative position its lower edge will be immersedin the metal inside the'kettle to a depth of about 16 inches approximately.

H is a tank containing chlorine which is led by a pipe E2 to amanifold or bustle pipe it which distributes the chlorine to a number of small These chlorine-pipes are composed of special nickel, molybdenum, chromium,

@ iron alloy tubes,.preferably the alloy known as Hastelloy which is resistant to chlorine and lead and tin chlorides at temperatures of the order of 1000 F. The tubes are approximately inside diameter when the dimensions given aelajcn chamber. They are such as to provide a proper working depth of lead chloride and stannous chloride but to minimize the quantity of chlorides required for the operation by confining such represents control valves and a flow meter for regulating the amount of chlorine passing to the bustle pipe l3 and thence into the chlorine pipes M. ,This assembly serves to deliver'chlorlne gas in a number of fine streams under con-,

trolled conditions. 7,

it represents a pipe for conducting tin tetrachloride formed in the reaction chamber away therefrom and into a pre-cooler .19, which is adapted to cool the gases and precipitate-any.

entrained stannous and lead chloride prior to the gases reaching the water-cooled condenser 20 in which the tin tetrachloride is condensed to a liquid which is collected in the. container 2| is that referred to in my copending application chlorides in a small space. This is an important 5 Ser. No. 120,877 above, and is composed of consideration because at the end of the opera crushed fire brick, Portland cement with high tion the amount of chlorides formed-in order to alumina content and sand. This cement as carryout the detinning operation is kept at a shown protects the various parts of the appaminimum and consequently the amount of pure l0 ratus which it surrounds from the corrosive acmetals recovered is correspondingly'larger. I i0 tion of the chlorine gas and molten chloride. have found that it is important to maintain a The pipe Lit will be noted passes through the sufilcient depth of metal chlorides in the reactop of this reaction chamber and terminates a tion chamber so that with spressure of 3 to 5 little below the top ofthe reaction chamber lbs, or perhaps a little more, of chlorine gas passing through the cement iii and discharging as I prefer to use, there is a sumcient depth of 145 into a substantially cylindrical space about the chlorides to react emciently with the chlorine center of the reaction chamber, into which space andmetallic lead and tin entering the chamber stannic chloride rises on its way out of the reso as'to avoid use of an excessive quantity of salt action chamber. Through the pipe I is adaptlayer. The dimensions of the chamber are also ed to be delivered molten metal including lead such that the amount of surface exposed to the andtin from the pump 6, the metal including corrosive action of the chlorine and molten chlolead and tin being constantly circulated through rides is about assmall as could be satisfactorily this chamber. While the pipe is shown as delivemployed for practical working conditions. ering the stream 01' metal including lead and tin Each of the chlorine feed pipes is connected 25 straight downward, it may be inclined at an with-the'bustle pipe by a T connection in which 25 angle so that the stream of metal will promote a is provided a cock 16 in order to regulate the instirring action of the contents in the chamber dividual flowthrough its feed pipe. The upper or the stream may be made to hit a baiile plate end'of each chlorine pipe is provided with a plug to subdivide it. lea, which may be removed in order to clean out The reaction chamber as shown is supported the pipe ii and when necessary. The numeral I1 45 herein for other parts of the apparatus are emsupported t erebelow- 22 s a p pe on uct 4i loyed. These tubes are protected by graphite the non-condcnsa c p r n f s p in from tubes me which are slipped over them, the it, and w ich su y consists g c n e. o a' graphite extending the entire length of the tubes W i we Which y be fil d wi h it inside the reaction chamber. The graphite tubes pa n material through which di e caustic 5 are held in place about the steel tubes by a cesoda solution is circulated by the system comi: ment Mb consisting of silica sand, finely groundv p d a p tank 25 Where the caustic a, brick and high alumina cement or sodium siliafter Passing through e w collects and cate. These chlorine pipes extend from the buso w c is P p y the m pr pe ated tle pipe through the cover of the reaction cham- P p 35 end returned to the D of e Washv her and being of sufilcient length so'that when 8' t we y the P p The pparatus in- 55 the reaction chamber is positioned about 16' cluding the pipe 22 and washing tower 23 is not inches below the surface of the metal, as indin ss e P Of the equipment It is p ocated above, the lower ends% of these chlorine Vlded catch y Volatile p u spass nc bepipes are about 3 to 5 inches below the surface y d th condenser it due to p r peraw of the metal bath inside the reaction chamber. t on of the Promise They surround the central space in the reaction 27 s e' p e e co nected to the chamber. The bottom edge i5 of the reaction p of e Washing tower 23 w ich serves to chamber is about 13 inches below the outlets of e p the entire a y em frolil reaction chamthe chlorine ipes 14. With these dimensions r to a d including t sh under a sli ht the diameter of the reaction chamber is approx-' l t8 imately 29 inches and its height approximately he p nof the pp t s Sh wn in Figs. 0 31 inches and the length of the chlorine tubes 1 to 4 is briefly as fcllcws- The metal alloy or f m the cover to their point of discharge in the othe metal mass containing d nd tin. with reaction chamber is about 18' inches; The dior without other ingredients, is melted inthe.

mensions are given because for the embodiment kettle I and heated to the te pe a ure e p y d 70 in operating the process as later described. The pump 6 is started to circulate the molten lead tin through the reaction chamber. Simultaneouslychlorine gas at a measured rate is allowed to flow into the molten metal from the chlorine shown I have obtained excellent results by having the parts proportioned as indicated, although the invention of1course is not restricted to such dimensions. These dimensions have :5 been worked out to give a practical reaction tank ll through the bustle pipe l3 and chlorine feed pipes. Tin tetrachloride is formed in the reaction chamber and volatilized. The vapor leaves the reaction chamber by means of the pipe f 18, passes through the pre-cooler l9 where occasionally small amounts of stannous and lead chlo- The cooled tin tetrachloride.

which is provided as a precautionary measure,-

passing in at the bottom of the tower 23 where the gases are washed with circulating dilute caustic soda.

In Fig. 5 there is shown a modified form of apparatus comprising two kettlesettings. Kettle 28 is preferably much larger than kettle 29. This apparatus is devised in order that a constant level may be maintained in kettle 29 during the operation. It will be understoodof course that in operating, for example as in Fig. 1, the mass of molten material in the kettle l gradually becomes lower due to the removal of tin as tetrachloride therefrom. Such lowering of the molten metal may be compensated for by feeding fresh metal into the pot during the early period of treatment, but this should be discontinued if the greater part of the tin is to' be separated as tin tetrachloride, if the operation is to be conducted economically. In addition it would be diificult, if not impossible, to raise and lower the reaction chamber, because of the various feed and delivery pipes connected to it, in order to keep it properly immersed in the shrinking bath if no new metal is added thereto. It is important that the relation of the tips of the chlorine feed pipes with the metal and chloride bath be maintained substantially as indicated above and if there is any substantial deviation the smooth progress of the reaction may be interrupted.

Accordingly I have provided in Fig. 5 an apparatus in which a constant level is maintained in the kettle 29. In this latter kettle the reaction chamber withits outer wall 8, chlorine pipes 14, bustle pipe 13 and other associated parts are the same as desribed in Fig. 1, and aresupported by a casting 30 on thetop of the kettle 29. This casting is preferably solid and provides a cover for the kettle 29. The kettle 28, however, contains the pump B-and pipe 1 leading therefrom into the reaction chamber. The pum'p 6 is supported by a casting 31 supported on the edges of the kettle. A pipe 31a serves to circulate the molten metal between the kettles 28' and 29. When the metal rises above the desired height in kettle, 29, it flows over into kettle 28. Bumers 32 and 33 may be introduced through the brick walls of the kettle supports 2 and either or both' kettles 23 and 29 maybe heated, if desired.

The modification shown in Fig. 7 is similar to that shown in Fig. 5, but kettle 28 in this instance is replaced by a furnace 34, which has an outside bay 35 communicating-with the interior, which bay contains a limited quantity of molten metal and in which baythe pump 6 is placed delivering molten metal by pipe- I to the reaction chamber. The kettle .29 is supported on a kettle base which in turn is elevated on a steel structure 39. The kettle is supported at'sufli cient height so that it is above the furnace 34' and so that an overflow pipe 31 will remove molten metal from the kettle 29 and depositit in the furnace 34 when the metal in kettle 2 9 rises above the desired level.

The operationof the apparatus shown in Figs. f

5 and? is similar to that shown in Fig. 1.

'A still further modification is shown in Fig. 6 to provide a substantially continuous process. In this instance three kettles 38, 39 and 40 are provided. The center kettle 38 corresponds to the kettle I in Fig. 1 and this kettle operates alternately with either kettle 39 or kettle 40. Some time may be lost in heating up a bath of metal to 1000-1050 F. which is the preferred temperature for detinning according to the process described below. Considerable time is also 'lost in cooling the metal bath after detinning so. that it may be cast. By the arrangement shown in Fig. 6 practically continuous operation may be maintained. While metal in kettle 40 is being detinned, the metal in 39'is being cooled, cast and a new lot introduced, melted and brought up to the temperature above mentioned. The reaction chamber is situated inkettle 38 and with its associated parts is substantially the same as that shown in Fig. 5, being supported by a solid casting which serves as a cover for the kett1e 38. Only a single pump 6 may be employed and when it has finished its operation in one kettie, 49 for example, it may be detached and transferred to the other kettle 39 for operation. Overflow pipes 41 and 42, provided respectively with stoppers 43 and 44, extend from the kettle 39 and deliver into the adjacent kettles, pipe M delivering into kettle 49 an'd'pipe 42 delivering into kettle 39. The operation of this embodiment is as follows. Metalis charged for instance into .kettle 39, heated to .a process temperature,

pumped through pipe I and delivered into the reaction chamber. Chlorine is delivered from its source through the bustle pipe 13 and chlorine pipes 14 into the reaction chamber and stannic chloride passes oil through pipe l8 through the condensing system shown in Fig. 1. During the processthe pump 6 is delivering the molten metal as stated through the pipe I to the' reaction chamber and the overflow pipe 41 being open by removal of its stopper 43, metal over--v flows from the kettle 38 into the kettle 40 and .then is again returned by the pump. Prior to the completion of the detinning of the metal in 49., another charge of metal is placed in kettle 39 and heated up to process temperature. When detinning is completed in 40 the pump 6 with its piping l is' shifted to kettle 39 and theprocess of detinning similar to that describedin connection with kettle 40 is carried on here, but at this time the overflow pipe 4| is closed. by stopper-43 so that the overflow occurs from pipe 42, its stop- Eli per 44 having been removed. While the detinning isv occurring in kettle 39,'the detinned materialin 49 is cooling and being cast. After the .detinning in kettle-'39, the process then proceeds in' 40 once more. In other words the kettles 39 and 40 are alternately used for the heating and detinning operation and then for the cooling opvention that when chlorine is injected into'fia molten lead-tin mixtureor alloy'with or-without= antimony, lead chloride and stannous chloride are formed and these salts will float to the surface. The reaction involved is:

If further chlorine comes in contact with these salts-lead chloride and stannous chloride, there wil be formed stannic chloride which is volatile at about 238 F., and the temperature of the lead chloride and stannous chloride being above thispoint, the stannic chloride will be volatilized and is removed from the mass. As the stannic chloride is removed, further quantities of stannous chloride must be formed, which in turn reacts with a further quantity of chlorine to produce stannic chloride.

I have found in accordance with my invention that-it is important to keep the five chief reacting materials involved in the production of tin tetrachloride from mixtures containing lead and tin, namely tin, lead, stannous chloride, lead chloride and chlorine, all in active contact with one another. It is important to have a large surface of chlorine exposed to the reacting materials. It. is also important to keep the metal salts in constant agitation so that the other three reacting materials may come in contact with them. If ordinary mechanical agitators are employed, it is diflicult -to keep any agitation equipment in operation because of' the terrific attack -by the chloride at the elevated temperature,

which I prefer to bein excess of 1000""F.

I have found that by introducing chlorine into a'reaction chamber in contact with molten metal containing tin and, lead and perhaps other ingredients, forming a' salt layer containing lead and stannous chloride and discharging a stream of molten metal containing lead/tin and pen ,haps other ingredients through this salt layer,

that I can satisfactorily produce tin tetrachloride. Under proper conditions which will be given in "greater detail below, the process can be conducted economically and efliciently. AlthoughI do not wish to be bound by the following explanation, there appears to occur under these conditions the establishment of an equilibrium or balance between the. components lead chloride, stannous chloride, lead and tin, which balance is being continuously upset by the introduction of further .quantitiesof chlorine. Chlorine reacts with the stannous chloride to form tin tetrachloride which is then volatilized. The equilibrium being upset is then restored by the formation of stannous chloride by reaction of tin with lead chloride.

The reactions mentioned are as follows:

' sn+c1=- snc12 SnCla+Cl2 SnCl4 (tin tetrachloride volatilizes) PbCla-i-Sn Pb+SnClz (stannous choride) The amnity of the different metals and their lower chlorides or chlorine are such that very little antimony or arsenic, if any be present,

goes into the salt layer and the resulting tin dinarily below the temperature'of the chlorinating zone. Even though the temperature of the salt layer in the reaction chamber tends to be higher than the molten bath of lead, tin and other metals with which it is in contact, nevertheless the temperature of this molten bath because of the large volume of metal therein is lower than that imthe reaction chamber and furthermore a certain amount of cooling of this molten metal occurs during the pumping operation so that the molten metal delivered by the pump into the reaction chamber is at a temperature where it aids in maintaining the tem-' perature of the reaction chamber within the desired limits. Accordingly after the chlorinating reaction has started in thereaction chamber, it is ordinarily not necessary to apply heat to the kettle to raise or maintain the temperature of the metal, but if this should be necessary of course the kettle may be heated bythe burner shown thereunder in the above embodiments of the apparatus.

The following is a description of an embodiment of the process as I now prefer to practice it: A charge of material containing lead and tin usually. in the form of a lead alloy of about important to keep the temperature somewhat above this melting point in order to avoidplugging the pipes ll through which the chlorine 8 's emerges. The molten alloy is circulated from the kettle I through the pump 6 and through the reaction chamber and chlorine is fed into the reaction chamber from the tank II. The chlorine reacts with the metal to build up a salt layer of. lead chloride and stannous chloride and the molten alloy passing into the reaction chamber.is discharged through this salt layer by the pump 6 at a rate of 25,000 to 40,000 lbs. per hour. The reaction chamber as noted in the description of the apparatus is suitably positioned below the surface of the molten metal. Where the diameter of the reaction chamber is about 29 inches and its height approximately 31" inches, the reaction chamber will be about 16 inches belowthe surface of the metal and the ends of the chlorine tubes from the cover of the reaction chamber to their point of discharge will be about 18 inches and they will terminate, therefore, about 13 inches from the bottom of the reaction chamber. The chlorine is delivered to the reaction chamber under a pressure of about 3 to 5 lbs. per square inch and the rate of delivery of the chlorine is controlled by the control valves and Percent tin in metal 1 5 3 2 13 1 s u 200 o.75. 100 0.50 50 During the first three or four hours of feeding chlorine gas, substantially no tin tetrachloride is Lead chloride has a melting layer formed is such that with chlorine gas at 3 to 5 lbs. per sq. inchthe chlorine will penetrate to and react as far as the bottom of the layer but will not emerge substantially beyond it. From this time on it appears that the chlorine gas entering the salt layer reacts with the stannous chloride to form a volatile tetrachloride and upon depletion of the stannous chloride in' this way the reactions above mentioned to reestablish the equilibrium appear to occur. When the metal left in the kettle I contains above 0.25% tin, the.

operation is considered finished as this is about the lowest content of tin that can be ordinarily obtained commercially. I

The tin tetrachloride produced is preferably conducted to a pre-cooler I9 where any entrained liquids or-high boiling liquids, which can be condensed at a higher temperature than that required for tin tetrachloride, are removed from the tin tetrachloride and returned to the'reaction, chamber by gravity. The tin tetrachloride vapor then passes to the condenser 20 where it is condensed to a liquid and is accumulated in the container 2| for subsequent use. Any tin tetrachloride not condensed in 20 or any chlorine gas notconsumed in the reaction chamber and passed along with the tin tetrachloride is washed out with caustic soda solution. -Very little chlorine gas in practice needs to be washed out as the efliciency of chlorine absorption in the reaction chamber is high.

At the end of a run which ordinarily lasts two to three days depending on the original tin content of the metal being treated, there-remains in the reaction chamber and floating on the metal bath about 2% of lead chloride of the original weight of alloy treated.

As the tin is eliminated as tin tetrachloride, the level of the metal-bath in the kettle I is progressively lowered. As it is important to keep the metal level approximatelyconstant for efficient operation, I feed in fresh quantities of metal to the kettle I during the run in order to maintain the original level. It is advantageous to use for this purpose metal richer in tin than the original metal so that the production of tin tetrachloride is maintained at the maximum.

I have treated compositions containing not only lead and, tin but also containing from 2.5 to 19%.

antimony and have found that the antimony contents had no adverse effects 'on the removal of the tin. In treating one composition which contained Per cent Tin 1.7 to 21 Bismuth 0 to' 7 Copper f trace to 5 Arsenic 0.1 to 4 Antimony 8 to 26 and the balance lead.

In accordance with my experience in practicing my invention, I have found that the best resultsare obtained when lead tin alloys are used which contain substantially no other ingredients or only small proportions of other ingredients which are present as the raw material subjected to the process. I do not add catalysts such as sulfides, antimony or other ingredients to the raw material being treated, and I prefer to remove sulphur if it is present in the metal being treated.

The tetrachloride of tin produced .by the process is remarkably pure when considering the impurity .of the various compositions treated. I have found it to contain not over .04 to .9 2% of such impurities with 99.96% to 99.08% of tin tetrachloride. The impurities found in the tin tetrachloride will depend upon the'quality of the metal being treated. The. apparatus described above has been used satisfactorily in the carrying out of the various process operations described.

A process which comprises among other things the maintenance of a substantially constant level in the kettle where the reaction chamber islocated may'be carried out for example employing an apparatus like that shown in Fig. 5. The lead and tin are melted in the kettles 28 and 29 and the pump 6 started in kettle 28, chlorine being fed to the reaction chamber through the tubes It. A

chloride layer forms in the reaction chamber floating on the molten metal beneath. Chlorine comes in contact with the chloride layer and the metal being circulated by the pump. The stream of metal passing through the chloride layer passes into the kettle 29 and then overflows through the pipe 2 la into the kettle 28. Stannic chloride is removed through the pipe l8 and'may be condensed as heretofore described.

A similar process may be carried out employing the apparatus shown in Fig. 7.

In carrying out a continuous process for separating tin as tetrachloride from alloys of mixtures containing tin and lead, I may employ an apparatus such as that shown in Fig. 6. Here lead is melted in the kettle 40 and pumped for example Iromyessel 40 through the reaction chamber'in vessel 38 where it comes in contact with a plural-. ity of streams of chlorine to form a separate layer of stannous chloride and lead chloride.

The

stream of molten lead pwses through the layer of vlead is heated in. the vessel 39 and circulated through the reaction chamber in contact with the streams of chlorine to form a molten chloride layer and to produce tin chloride. During this operation the metal in 40 is cooling so that it may be cast. It is removed when cool and then prior to the detinning of the material in the kettle 39 a fresh lot of tin and lead isv placed in kettle 40 and heated up so thatjfwhen the detinning operation ceases in kettle 39, another operation may .be started on the new metal inkettle 40 so that the process is operated continuously.

While the invention has been described in detail with respect to particularpreferred examples,'it will be understood by those skilled in the What is claimed as new and desired to be secured by Letters Patent of the United States is: 1. In apparatus for treating metals in combination, a container for molten metal, a reaction chamber within it and near the top thereof and opening into said container, means to circulate said metal from said container through 'said reaction chamber and back to said container, means to maintain a layer of chlorides on top of the molten metal in said container and within said reactionchamber, and means-for passing chlorine in streams into said layer of chlorides.

2, In apparatus for treating metals in combination, a container fo molten metal, a reaction chamber within itZand near the top thereof and opening into sai container, 9. pump suspended in the container to circulate said metal from said container through said reaction chamber and back to said container, means to form streams of chlorine in said reaction chamber to react with said metal to form a layer of chlorides whereby when the molten metal is in the container the chlorinated metal fioats thereon in the reaction chamber, the molten metal is circulated through the 1 chlorides and the chlorine passes into the chlorides in the reaction chamber.

3. In apparatus for treating metals in combination, a container for molten metal, a reaction chamber within it and near the top thereof and opening into said container, means located from to said reaction chambenand a series of pipes in said reaction chamber to conduct the chlorine therethrough in streams and to react with said metal to form a layer of chlorides whereby when the molten metalis in the container the chlorinated metal floats thereon in the reaction chamber, the molten metal is circulated through the chlorides and the chlorine passes into the chlorinated metal in the reaction chamber.

4. In apparatus for treating metals in combination, a kettle for molten metal including lead and tin, a reaction chamber within it open at the bottom and adapted to dip into the metal and allow the metal to rise therein when the latter fills the kettle to a point near the 'top, said chamber being lined with material refractory to lead and tin chlorides at a temperature about 1000-1050 F., a pump in saidkettle to circulate said metal from the kettle through said reaction chamber and back to said kettle, a source of chlorine delivering chlorine to said reaction chamber and a series of metal alloy tubes surrounded by graphite and passing through the refractory material to a position a short distance above the lower edge of the reaction chamber, said tubes being adapted to conduct chlorine in a series of streams into an open space in the reaction chamber adapted to be partially occupied by said molten metal, whereby upon chlorine cominginto contact with the molten metal in the reaction chamber a layer of chlorinated metal is formed floating on the molten metalbeneath and when the molten metal is pumped from the kettle to the reactioii chamber it passes through the chlorinated metal layer at the same time that the chlorine "passes, ir'itocontact with the stream of molten metal delivered by the and the chlorinated means for circulating metal from below saidlayer and discharging it above and into said layer, means to conduct away the volatile chloride of tin, and a condenser to condense and recover said volatilized tin.

6. In apparatus for treating metals in combination, a container for molten metalincluding tin, a reaction chamber near the top thereof and opening into said container, a second container for molten metal, means to circulate said metal successively through the containers and the reaction chamber, means to bring streams of chlorine in said reaction chamber into reaction with said metal to form a layer of chlorides, and to form and remove stannic chloride from the reaction chamber whereby the level of the molten metal in said first mentioned container may be maintained substantially constant'regardless of the removal of tin as tin tetrachloride from the molten metal.

7. In a continuous apparatus for separating tin from alloys or mixtures containing tin and lead in combination, a reaction kettle having a reaction chamber. located therein, a second kettle communicating therewith, and a third kettle communicating with said reaction kettle, said second and third kettles being adapted to be I alternatively put in communication with said reaction kettle, apump adapted to be located alternatively in the second or third kettle for circulating molten metal from for example the secgnd kettle in which it is located through the the reaction chamber continuously, whereby two lots of metal may be successively acted upon in thereaction chamber and after one lot has been treated itmat be allowed to cool for casting while the second lot is being passed through the reaction chamber.

8. In an apparatus for treating metals in com- I bination, means to maintains. layer of tin and lead chlorides on top of a molten metal bath containing tin and 1e d, means for passing chlorine into said layer 0 chlorides, and means for circulating metal from below said layer and dis-'- charging it on or into said layer.

9. A reaction chamber for the separation o metallic constituents of metals or alloys of the ture of leadand tin by a treatment of vapor of halogen consisting of a hollow metallic body suspended in the molten metal or alloy in such a manner that an eiiicient seal is obtained, distributing ducts penetratingsaid hollow ,metallio J body and ending in openings in a substantially non-metallic" refractory lining adjoining said "hollow metallic body, an opening above the level of the molten metal or alloy for the admisexit of reaction products.

'sion of saline into said reaction chamber and an

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