BE476139A

BE476139A -

Info

Publication number: BE476139A
Authority: BE

Description

       

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  " Perfectionnements apportés aux procédés et appareils pour purifier des métaux   ".   



   La présente invention est relative à des procédés et   appareils pour purifier des métaux ; elle concerne,   plus spécialement, des procédés et appareils pour séparer le plomb, en tant qu'impureté, de l'étain et qui convien- nent surtout à enlever des quantités réduites de plomb hors d'un étain qui, à part cela, serait pur. 



   Il est bien connu que, lorsqu'on enlève de petites hors quantités en plomb/de l'étain par chloruration à des températures réduites, la scorie obtenue est pauvre en chlorure de plomb et riche en chlorure stanneux. Ilest également connu que, si l'enlèvement du   plmb   hors de l'étain par chloruration a lieu à des températures éle- vées, les chlorures du plomb et de l'étain se volatilisent 

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 tous deux et doivent donc être recueillis dans des appareils condenseurs dans lesquels on peut essayer de séparer les produits. Il est évident que ce mode de traitement nécessite l'intervention d'appareils com- pliques dent la construction et le fonctionnement impli- quent un problème sérieux et difficile à cause de la nature corrosive de ces produits.

   Un grand nombre d'autres procédés et appareils peuvent avoir été proposés pour séparer le plomb et l'étain à l'aide de chlore eu de chlorures, mais aucun d'entre eux ne présente un carac- tère de simplicité, d'efficacité et de nouveauté analo- gue à ceux qui font l'objet de l'invention. 



   Le procédé et l'appareil, faisant l'objet de l'in- vention, permettent de réduire la teneur en plomb d'un bain d'étain fondu, contenant un peu de plomb, à moins de 0,05 pour cent. Le plomb est recueilli sous forme d'un résidu de creuset en séparant le SnCl2pas distil- lation du mélange Sncl2 Pbcl2 et en ramenant le   SnCI   exempt de plomb dans une cuve pour l'enlèvement du plomb. 



   L'enlèvement du plomb hors de l'étain à l'aide de chlore est basé sur la plus grande affinité du chlore pour le plomb que pour l'étain. Si un alliage plomb-étain est traité avec une quantité donnée de chlore, une scorie de PBcl2 sncl2 se forme sur le métal et dans   laquelle   le   rapport   plemb-étain atteint   en   fin de compte une valeur   définie   qui   dépend   du rapport final plobm-étain de   l'alliage   sur lequel la scorie repose. 



  La réaction 
Pb + SnCl2 PbCl2 + Sn est réversible . Four qu'elle ait lieu dans   l'un.   ou l'autre sens il est nécessaire d'enlever un desproduits de la réaction pour empêcher que l'on obtienne un état d'équilibre entre la composition de l'alliage et celle de la scorie . 

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   L'invention est basée sur le principe que, si l'on ajoute continuellement du sncl2 au système plomb, étain , chlorure de plomb et chlorure stanneux, tel qu'indiqué plus haut, la réaction va de gauche à droite et que si le PbCl2 est continuellement enlevé hors de ce système, la totalité, pour ainsi dire, du plomb aura été séparée d'avec l'étain. 



   A cet effet, on enlève, d'une manière continue, la scorie pbcl2 sncl2 du bain métallique et on l'intro- duit dans un creuset dans lequel la température de la scorie est augmenté en vue d'en séparer le sncl2 par distillation et ce dernier est ramené dans le bain métal- lique dans lequel il réagit avec le plomb de ce bain pour former du PbCl2 et de l'étain métallique selon l'équation indiquée plus haut en   gênant   la formation de plus de sncl2 et en accélérant la formation de pbcl2 De cette manière, le PbCl2 s'accumule continuellement dans le creuset 'alors .que le sncl2 circule constamment et est ramené au creuset en entraînant un peu de plomb. 



  De cette manière on peut séparer, pratiquement, tout le plomb de l'étain. 



   Le dessin ci-annexé montre, à titre d'exemple, un mode de réalisation d'un appareil convenant à la mise en oeuvre de l'invention. 



   Les figs. 1 et 2 montrent, respectivement en coupe verticale (parties en élévatiori) et en plan (parties en coupe), un tel appareil. 



   Sur le dessin on a désigné par 1 une cuve pour l'en- lèvement du plomb et qui est montée sur un support appro- prié 2. La cuve 1 est fermée à l'aide d'un couvercle 3 qui est convenablement maintenu en place. Un moteur électrique   4,   monté sur un support approprié 5, entraîne un arbre   ventical   6 qui traverse le couvercle 3 et dont l'extrémité inférieure porte un agitateur 7. 

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   Sur la face interne de la paroi de la cuve est fixée une pièce coudée 8 qui forme une chambre propre à recueillir les scories et qui est ouverte vers le haut et le bas. Dans la paroi de la cuve 1 est   ménagée   une ouverture   la   qui fait communiquer la chambre à scories avec un conduit incliné 9 débouchant dans un creuset 10, conve-   nable-.lent   supporté et fermé par un couvercle 11 . A proxi- mité de son   extrémité   supérieure, le   creuset   10 communi que avec un deuxième conduit incliné 12 qui débouche dans un tube vertical 13   relié à   la cuve 1 par une ouverture 3a   ménagée   dans le couvercle 3, le tube 13 étant   fermé.   par un bouchon amovible   14.   



   Conformément à l'invention, le couvercle 3 peut porter un entonnoir 15 qui peut être   fermé,   d'une manière étanche, par un registre 16. De plus, ledit   couvercle   peut porter un tube 17 qui peut être   formé   par un robinet 18 L'entonnoir 15 et le tube 17   communiquent   avec   l'inté-   rieur de la cuve par ;les ouvertures ménagées à cet effet dans le couvercle 3. 



   De plus et   comme     montré,     un   dispositif de chauf fage   approprié   19 est adjeint à la cuve 1 et un brûleur 20 est établi sous le creuset 10. 



     Apres   qu'une quantité convenable d'étain fondu et contenant du plmb a été pompée ou introduite de toute autremanière dans la cuve 1, le traitemet de fait de la manière   suivante .  Au début il est nécessaire   d'établir   une couverture ou couche supérieure de Sncl2 sur l'étain fondu contenant du plomb et ceci peut être réalisé de différentes manières . Ainsi, c-es scories de Sncl2 peuvent être introduites   cians   la cuve 1 par   l'entonnoir   15 après que le registre 16 a été ouvert, ce dernier étant refermé après que la quantité voulue de scories Sncl2 a été introduite dans la cuve 1.

   Suivant une variante et en vue de chlorer une partie de l'étain, du chlore gazeux peut      

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 être introduit dans la cuve 1 par le   tube'17   avec robinet 18 On peut également introduire des vapeurs de Sncl2 dans la cuve 1 depuis le creuset 10 lequel,comme décrit ci-après, forme une source d'alimentation de ces vapeurs. 



   Après avoir procédé ainsi, on fait fonctionner le dispositif de chauffage 19 de manière que le bain de métal, contenu dans la cuve 1, reste à une température variant entre 245 c et 315 C. A ce moment le moteur   4   est mis en marche pour faire tourner l'agitateur 7 à une vitesse convenable de sorte que le Sncl2 réagit avec le plomb pour former une couche de scories d de/pblc2 et de SnCl2 qui repose sur le bain d'étain métallique b .

   Pen- dant ce traitement, la couche de scories est recueillie dans la chambre à scories, délimitée par la pièce 8 et hors de laquelle les scories s'écoulent, par le conduit 9, dans le creuset, cette opération se   faisant,évidemment,   d'une manière continue 
Fendant que cette, opération a lieu, on fait fonction- ner le brûleur 20 de manière que la matière, contenue dans le creuset, reste à une température comprise entre 650 C et   700 C.   De cette manière, le SnCl2 se sépare, par dis- tillation, du chlorure de plomb et retourne, par le tube 12, dans la cuve 1 dans laquelle il réagit à nouveau avec le plomb métallique, contenu dans celle-ci, pour former du chlorure de plomb additionnel qui, à son tour,passe sous forme d'une scorie dans le creuset 10 afin que le procédé puisse continuer .

   A ce sujet il y a lieu de noter que la tension de vapeur dans le creuset 10 doit devenir suffisamment élevée pour que les vapeurs de Sncl2 puissent passer du creuset 10 dans la cuve 1 par le tube 12 pour se condenser dans ledit conduit ou dans la cuve. 



   De cette manière, la presque totalité du plomb est séparée d'avec l'étain dans la cuve 1 et le plomb ainsi 

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 enlevé reste bien entendu dans le creuset 10. Quand le   traitement   est presque achevé, la.   température   des ma   tières,   contenues dans le creuset 10,peut être   augmentée   jusqu'à environ 815 c une température aussi élevée étant utilisée pour expulser autant de   SnCl   que possible hors du creuset 10 sans   qu'elle   soit assez importante pour vaporiser le chlorure de plomb. De cette manière le résidu plombifère restant dans le creuset 10'   a   une teneur aussi élevée que possible en plomb.

   Ce   résidu est   enlevé de temps en temps hors du creuset 10 suivant la quantité de plomb qui se trouve dans l'étain initial, introduit dans la cuve 1. Le chlorure stanneux est   fondu     pour   récupérer 1'étain. 



   On a/trouvé qu'un creuset ordinaire 10 , en fer, quand il est utilisé pour le procédé en question, ne résis- te pas longtemps à l'action corrosive du   PbCl   et du Sncl2 Des alliages spéciaux ou un métal tel que le cuivre ou analogue sont nécessaires pour des applications indus-   trielles .   On a constaté que le produit, connu sous le nom de   "Hastelloy   B" résiste très bienà cette action corro- sive . 



   Comme   il   va de soi et   comme   il résulte déjà de ce qui   précède, l'invention   ne se limite nullement à celui de ses modes xx d'application non plus qu'à ceux des modes de réalisation de ses diverses parties, ayant été plus spécialement   indiqués;   elle en embrasse, au contraire, toutes les variantes. 

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  "Improvements in methods and apparatus for purifying metals".



   The present invention relates to methods and apparatus for purifying metals; it relates, more particularly, to methods and apparatus for separating lead, as an impurity, from tin and which are especially suitable for removing reduced quantities of lead from a tin which, apart from that, would be pure.



   It is well known that when small amounts of lead / tin are removed by chlorination at reduced temperatures, the slag obtained is poor in lead chloride and rich in stannous chloride. It is also known that if the removal of plmb from tin by chlorination takes place at high temperatures, the chlorides of lead and tin volatilize.

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 both and must therefore be collected in condensing devices in which we can try to separate the products. It is evident that this method of treatment requires the intervention of complicated apparatus, the construction and operation of which is a serious and difficult problem due to the corrosive nature of these products.

   A large number of other methods and apparatus may have been proposed for separating lead and tin using chlorine or chlorides, but none of them is of a character of simplicity, efficiency and effectiveness. novelty analogous to those which are the subject of the invention.



   The method and apparatus, object of the invention, reduce the lead content of a bath of molten tin, containing some lead, to less than 0.05 percent. The lead is collected as a crucible residue by separating the SnCl2pas distillation from the Sncl2 Pbcl2 mixture and returning the lead free SnCl to a lead removal tank.



   The removal of lead from tin using chlorine is based on chlorine's greater affinity for lead than for tin. If a lead-tin alloy is treated with a given amount of chlorine, a PBcl2 sncl2 slag forms on the metal and in which the pbm-tin ratio ultimately reaches a defined value which depends on the final pbm-tin ratio of the alloy on which the slag is based.



  The reaction
Pb + SnCl2 PbCl2 + Sn is reversible. Oven that it takes place in one. either way it is necessary to remove one of the reaction products to prevent a state of equilibrium between the composition of the alloy and that of the slag being obtained.

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   The invention is based on the principle that, if sncl2 is continuously added to the lead, tin, lead chloride and stannous chloride system, as indicated above, the reaction goes from left to right and that if PbCl2 is continuously removed out of this system, all, so to speak, of the lead will have been separated from the tin.



   To this end, the pbcl2 sncl2 slag is continuously removed from the metal bath and is introduced into a crucible in which the temperature of the slag is increased in order to separate the sncl2 therefrom by distillation and the latter is brought back into the metal bath in which it reacts with the lead of this bath to form PbCl2 and metallic tin according to the equation indicated above, hindering the formation of more sncl2 and accelerating the formation of pbcl2 In this way, the PbCl2 accumulates continuously in the crucible while the sncl2 circulates constantly and is brought back to the crucible with some lead entrained.



  In this way, practically all the lead from the tin can be separated.



   The accompanying drawing shows, by way of example, one embodiment of an apparatus suitable for implementing the invention.



   Figs. 1 and 2 show, respectively in vertical section (parts in elevation) and in plan (parts in section), such a device.



   In the drawing there is designated by 1 a tank for the removal of lead and which is mounted on a suitable support 2. The tank 1 is closed by means of a cover 3 which is suitably held in place. . An electric motor 4, mounted on a suitable support 5, drives a ventilation shaft 6 which passes through the cover 3 and whose lower end carries a stirrer 7.

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   On the internal face of the wall of the tank is fixed an elbow piece 8 which forms a chamber suitable for collecting the slag and which is open upwards and downwards. In the wall of the tank 1 is formed an opening 1a which communicates the slag chamber with an inclined duct 9 opening into a crucible 10, suitable slowly supported and closed by a cover 11. Near its upper end, the crucible 10 communicates with a second inclined duct 12 which opens into a vertical tube 13 connected to the tank 1 by an opening 3a made in the cover 3, the tube 13 being closed. by a removable cap 14.



   According to the invention, the cover 3 can carry a funnel 15 which can be closed, in a sealed manner, by a register 16. In addition, said cover can carry a tube 17 which can be formed by a valve 18 L '. funnel 15 and tube 17 communicate with the interior of the tank through the openings provided for this purpose in the cover 3.



   In addition and as shown, a suitable heating device 19 is added to the vessel 1 and a burner 20 is established under the crucible 10.



     After a suitable quantity of molten tin and plmb containing has been pumped or otherwise introduced into vessel 1, processing is carried out as follows. In the beginning it is necessary to establish a cover or top layer of Sncl2 on the molten tin containing lead and this can be done in different ways. Thus, these Sncl2 slags can be introduced into tank 1 through funnel 15 after register 16 has been opened, the latter being closed after the desired amount of Sncl2 slag has been introduced into tank 1.

   According to a variant and with a view to chlorinating part of the tin, gaseous chlorine can

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 can also be introduced into the vessel 1 through the tube '17 with tap 18 Sncl2 vapors can also be introduced into the vessel 1 from the crucible 10 which, as described below, forms a supply source for these vapors.



   After proceeding in this way, the heating device 19 is operated so that the metal bath, contained in the tank 1, remains at a temperature varying between 245 ° C. and 315 ° C. At this time, the motor 4 is started for rotate the stirrer 7 at a suitable speed so that the Sncl2 reacts with the lead to form a slag layer d of / pblc2 and SnCl2 which rests on the bath of metallic tin b.

   During this treatment, the slag layer is collected in the slag chamber, delimited by part 8 and out of which the slag flows, through line 9, into the crucible, this operation being done, of course, d 'continuously
While this operation is taking place, the burner 20 is operated so that the material contained in the crucible remains at a temperature between 650 C and 700 C. In this way the SnCl2 separates out, by saying. - tillation, lead chloride and returns, through tube 12, to tank 1 in which it reacts again with the metallic lead, contained therein, to form additional lead chloride which, in turn, passes as a slag in crucible 10 so that the process can continue.

   In this regard it should be noted that the vapor pressure in crucible 10 must become sufficiently high so that the Sncl2 vapors can pass from crucible 10 into vessel 1 through tube 12 to condense in said conduit or in the pipe. tank.



   In this way, almost all of the lead is separated from the tin in tank 1 and the lead as well.

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 removed remains of course in the crucible 10. When the treatment is almost completed, the. temperature of the materials contained in crucible 10 can be increased to about 815 ° C. such a high temperature being used to expel as much SnCl as possible out of crucible 10 without being large enough to vaporize the lead chloride . In this way the lead residue remaining in the crucible 10 'has as high a lead content as possible.

   This residue is removed from time to time out of crucible 10 depending on the amount of lead which is in the initial tin, introduced into vessel 1. The stannous chloride is melted to recover the tin.



   It has been found that an ordinary crucible 10, made of iron, when used for the process in question, does not withstand the corrosive action of PbCl and Sncl2 for long. Special alloys or a metal such as copper or the like are needed for industrial applications. The product known as "Hastelloy B" has been found to resist this corrosive action very well.



   As goes without saying and as it already follows from the foregoing, the invention is in no way limited to that of its modes of application xx nor to those of the embodiments of its various parts, having been more especially indicated; on the contrary, it embraces all the variants.

** ATTENTION ** end of DESC field can contain start of CLMS **.

Claims

CLAIMS 1. Procedure for removing lead as an impurity from tin, characterized in that a layer of stannous chloride and lead chloride slag forms on a mass of molten tin containing lead as an impurity , by removing the slag from the molten tin and <Desc / Clms Page number 7> which separates the stannous chloride from the chloride of lead.

2. A process for removing lead as an impurity from tin, characterized in that a layer of stannous chloride and lead chloride slag is formed on a mass of molten tin containing lead. as impurity, in that the slag is passed through a crucible, in that the temperature of the crucible is maintained sufficiently high for the stannous chloride to separate, by distillation, from the chloride of lead, and in that the stannous chloride is brought back to the zone occupied by the mass of molten tin.

3. A method of removing lead, as an impurity, from tin, characterized in that a layer of stannous chloride and lead chloride slag is formed on a mass of molten tin containing lead, as impurity, in that the slag is removed and passed through a crucible under the action of gravity, in that the temperature of the crucible is maintained high enough to cause the separation of the stannous chloride, by distillation of lead chloride, and. in that, thanks to the pressure existing in said crucible, the stannous chloride is brought back to the zone occupied by the mass of molten tin.

4. A process for removing lead as an impurity from tin, characterized in that tin containing lead as an impurity is melted, and a layer of stannous chloride is produced. on the surface of the molten metal, in which the ion agitates the molten metal so as to cause the stannous chloride to react with the lead and thus to produce a layer of slag of stannous chloride and of lead chloride, in that one raises the temperature of the slag layer, after separation of this layer from the melting zone, so as to separate the stannous chloride from the lead chloride by distillation and in that one brings back <Desc / Clms Page number 8> stannous chloride at the melting zone.

5. A method of removing lead as an impurity from tin, characterized in that tin containing lead as an impurity is melted, in that a layer of stannous chloride is produced on the surface of the tin. molten metal, in that the molten metal is stirred so as to cause the stannous chloride to react with the lead and thus to produce a layer of theories, the chlorurestannous and of lead chloride, in that the layer is passed through of slag to. a zone,

in which the stannous chloride is separated from the lead chloride, and in that the stannous chloride is returned to the melting zone.

6 Process for removing lead, as an impurity, from tin, characterized in that tin containing lead as an impurity is melted, in that a layer of stannous chloride is produced on the surface of molten metal, in that the molten metal is stirred so as to cause the stannous chloride to react with the lead and thus to produce a layer of slag of stannous chloride and of lead chloride, in that the layer is collected of slag and is brought into a crucible under the action of gravity, in that the temperature of the crucible is maintained high enough to separate, by distillation, the stannous chloride from the lead chloride,

and in that the stannous chloride is returned to the melting zone.

7. A method of removing 'lead as an impurity from tin, characterized in that tin containing lead as an impurity is melted, in that a layer of stannous chloride is produced on the surface of the tin. molten metal, in that the molten metal is stirred while maintaining its temperature between 245 and 315 C., so as to cause the stannous chloride to react with the lead and thus to produce a layer of slag of-, .stannous chloride and chloride <Desc / Clms Page number 9> lead, in that the layer of slag is brought to a crucible, in that the temperature of the crucible is maintained between 650 and 700 C., so as to separate, by distillation, the stannous chloride from the chloride of lead and which brings the chlorurethane back to the melting zone.

8. Process for removing lead, as an impurity, from tin, characterized in that tin containing lead as an impurity is melted, in that a layer of stannous chloride is produced on the surface of the tin. molten metal, in that the molten metal is stirred while maintaining its temperature between 245 and 315 C., so as to cause the stannous chloride to react with the lead and thus to produce a layer of stannous chloride slag and lead chloride, in that the layer of slag is brought to a crucible, in that the temperature of the crucible is maintained between 650 and 700 C, so as to separate, by distillation, the stannous chloride from the lead chloride, and in raising the temperature of the crucible to 115 C.

approximately, when the tin in the melting zone becomes substantially free of lead.

9. In the technique of separating lead, as an impurity from tin, the operations of continuously passing stannous chloride and lead chloride slag from a vessel to a crucible, to separate, by distillation, the stannous chloride from the lead chloride in the crucible, and to return, in a continuous manner, the stannous chloride in the form of vapor from the crucible to the tank.

10. In the technique of separating lead, as an impurity from tin, the operations consisting in continuously passing slag of stannous chloride and lead chloride into a crucible from 'a vat containing tin and lead, as an impurity, <Desc / Clms Page number 10> in the molten state, to be separated by distillation, the stannous chloride from the lead chloride in the crucible, xxxxx continuously returning the stannous chloride in the form of value from the crucible to the tank,

and stirring the molten notai in the vessel so as to cause the stannous chloride to react with the lead and thereby produce a new charge of stannous chloride slag and lead chloride.

11. In the technique of separating lead, as an impurity from tin, the operations of continuously passing stannous chloride and lead chloride slag into a crucible from a vat containing tin and lead, as impurity, the molten state, to maintain the temperature of the crucible between 650 and 700 C so as to separate, by distillation, the stannous chloride from the plumb chloride, to be brought back, so continues, stannous chloride in the form of vapor from the crucible to the tank, and to stir the molten metal in the tank,

while maintaining the temperature thereof between approximately 245 and 315 ° C so as to cause the stannous chloride to react with the lead and thereby produce a new charge of stannous chloride and lead chloride slag.

12. In the technique of separating lead, as an impurity, from tin, the operations consisting in continuously passing slag of stannous chloride and of lead chloride through a crucible from a crucible. 'a vat containing tin and lead, as an impurity, in the molten state, to. maintain the temperature;

crucible initially between 650 and 700 c and subsequently at about 815 c fail to cause the separation, by distillation, of the stannous chloride and the lead chloride, to bring back continuously the <Desc / Clms Page number 11> stannous chloride in the vapor state from the crucible to the vessel, and stirring the molten metal in the vessel while maintaining the temperature thereof approximately between 245 and 315 C, so as to cause the stannous chloride to react with the lead and thus produce a new charge of stannous chloride and lead chloride slag.

13. Apparatus of the type described, comprising a tank with which is associated; a crucible, means in the tank for stirring a mass of molten metal enclosed therein, a slag passage duct connecting the tank to the crucible and a vapor passage duct connecting the crucible to the tank, the inlet end of the duct last mentioned being arranged in the vapor space of said crucible and its outlet end being located above the level of the molten metal in the vessel.

14, Apparatus of the type described comprising a vessel with which is associated a crucible, means in the vessel for stirring a mass of molten metal enclosed therein, a slag passage duct connecting the vessel to the crucible, a slag trap provided in the tank and associated with the inlet end of the slag passage duct, and a vapor passage duct connecting the crucible to the tank, the inlet end of the last mentioned duct being provided in the space steam from said crucible and its outlet end being located above the level of the molten metal in the vessel.