US830051A - Apparatus for the electrolytic extraction of metals. - Google Patents

Description

PATENTED SEPT. 4, 1906.

0. F. CARRIER, J11. APPARATUS FOR THE ELECTROLYTIC EXTRAGTIONOP METALS.

APPLICATION TILED JAH.30,1905.

A T J .N N 8 WW Cw am A w W a Y j 8 W UNITED @TATES PATENT @FFIGE.

COURTLA ND F. lARRlER, JR, OF ELMIRA, NElV YORK, ASSIGNOR TO ELMIRA liLECTlii)CHEMICAL COMPANY, OF ELMIRA, NEW YORK.

AFPARATUS FOR THE ELECTROLYTIC EXTRACTION OF METALS.

Specification of Letters Patent.

Patented Sept. 4, 1906.

Application filed January 30,1905. Serial No. 243,184.

To all Ill/b07121 it Hm/y con/(107 12,:

Be it known tliatl, UoUR'rLAN'n F. CAR- nLaR, J12, a citizen of the United States, residing at Elmira, in the county of Chemung and State of New York, have invented certain new and useful Improvements in ratus for the Electrolytic Extraction of Metals, of which the following is a specification.

My invention relates to improvements in a paratus for carrving on the processes for tl fe electrolytic extraction of metals which re lighter than the electrolytes from which the are separated; and my object is to provide certain novel features in the construction of such a paratus whereby the efhciency and facility 0 working such processes will be increased and the cost of producing these nietalswill be diminished.

I attain my object by the arrangement of the several parts of the apparatus, as illustrated in the accompanying drawings, in which Figure 1 is a longitudinal vertical section of an electric furnace embodying my improvements, and Figs. 2 and 3 vertical transverse sections of the same on the lines a a and b b in Fig. 1 lookin to the right.

Like numerals designate fike parts in the several views.

Referring to the drawings, 1 indicates a large pan which is set 111 a mass of masonrv This pan is best made of cast-iron and is preferablv of rectangular form. The

middle portion of the bottom is raiscdis'omewhat above the level of the two end portions, this raiscd'portion extending across the entire' width of the pan, forming a shallow portion at the center and depressions of greater depth at each end. The other parts of the furnace up to and ncluding 18 are supportod within this pan by means of iron cleats 3, cast wit h the pan or riveted to the sides or by other uitable moans.

1-: raised portion of the pan is lo- Lili anorie-compartment, which is in- :i i rtzirm'ular frame 4, preferably of T is 1 rams lined with basic maas macis or other material, not be atii ed by the electrolyte n elf during the process.

Ul ill (.1 k

upiicd with feed- .1 sn pp of electrol provided for the Appaclosed at the top bv a" l "lizil s1 imlar to the- .uimble material for l the anodes is graphite. To protect the anodes from the action of the gases, they are l surrounded by sleeves 10 of the same. material as the lining. The feed-holes are covered with small slabs 1 1 of this same material or of soapstone. The number of anodes used may vary within the limits of practicability, according to the capacity desired, the width of the furnace being increased to accommodate the desired number. At the back of the furnace is located a port 12 for conducting off the gases evolved during the process.

The cathodc-compartments are two in anode compartment. Each cathode com- I partment consists of a rectangular metal box 13, preferably of cast-iron, which is closed upon all sides except the bottom, forming a rectangular bell. The cathode itself consists of a flat iron plate 14, the lower surface of which is slightly inclined upwardly from the sides toward the center and toward one end. This plate istsupported by a heavy lug 15, which is insulated from the bell 13 bv a sleeve .16, which may be of porcelain or other suitable material. The electrolyte 17 is only deep enough to touch the entire lower surface of the cathode. Just below the surface of the electrolyte is located a small iron pipe 18, which extends entirely around the compartment. This serves to carry cooling-water, the purpose of which will be explained later. The iron pipe 19 is to carry the liquid metal from the furnace. This pipe is insulated from the pan and carried from the furnace by means of the concentric sleeve 20, which is fastened to the pan. Both pipe and sleeve project several inches from the furnace. At the outer end the space between the pipe and sleeve is filled with a ring 21 of suitable packing material, such as fire-clay. In the portions of the pan remaining between the cathodc-compartmcnts and the ends are located the means of circulatingithe metal or alloy with which the pan is partially filled. Each consists of a rectangular mass of iron 22, cast hollow, which is caused to move slowly up and down by means of the crankshafts 23. The two pistons are so regulated that while one is thrust downward the other is drawn upward. In this way the molten metal is caused across theraised portion of the pan beneath the anode-compartment. At the ends of the pistons are lugs 24, which fit loosely into iron to flow back and forth land! or steel guides 25 on the sides of the pan and constrain the pistons to move in a vertical plane.

Beneath the ends of the pan are gas-burners 26 for-the purpose ol heating the apparatus on startin, and to keep it hot during any temporary interruption of the current, the passage of which under normal Working conditions may supply suilit'ient heat to keep the contents of the furnaccin a molten condition, or they may he used as a continuous source of heat during the action of the process. l/Vhere gas is not available, ordinar lire-places may he used instead of the more convenient gas-burners.

The relation of the various parts to one another and their special adi'antagcs may he much more clear-l; understood by considering a concrete example of the Working of the apparatus. The metal lighter than the electrolyte from which it is extracted that has the largest comn'iercial demand is sodium, and the cheapestava ilahle source is sodium chlorid or common salt. We will therefore consider the production of that metal from salt by means of this improved apparatus. Assuming that the various parts are arranged according to the preceding description, We proceed as follows:

The anode 9 is connected with the positive terminal of a source of electricity and the two cathodes 14' with the negative terminal. The furnace is heated to over 350 Centigrade by means of the burners 26. The pan is now filled Witha hodjvof molten lead 27, sufficient to form a li'uid seal at the bottom of the three electrolh'tic compartments. Tin, cadmium, or certain alloys 0. ow melting-point may also be used; hut lead is the cheapest metal which will perform the desired functions. The cathode-compartments are then filled with molten caustic soda (sodium hydroXid) or other suitable electrolyte to the level of the lower surface of the cathode 14. The caustic soda and lead are readil kept in a molten condition hy means of the burners. The anode 9 is lowered until almost in contact with the lead, salt is piled around it, and the current started. The pistons i'or circulating the lead must also he set in motion. At first the current should not he allowed to pass to the cathodes, but should he conducted away by means of temporary contacts with the pan. if this is not done, the lead will he attacked in the cathode-compartment. for there Will not be enough sodium present to protect the lead.

electric arc which melts the surrouu'ling salt. This requires a temperature of 800 to 900 ccntigrade. As soon as enough salt is melted to cover the end of the anode the arc will he lhc passage ol the cur rent irom the 'anoce to the lead lorms an anode and cathode, will hereinafter he kn n as the secondary anode and secoi'idar v cathode. The primary electrodes will he referred to simply the anode and cathode, respectively.

The chlorin escapes as a gas and isconveyed away through the port 12. The sodium is absorbed by the molten lead-forming an alloy. The advantage ofhavi the sodium During tais period The anode 9 and the cathodes 14' n I O set free in this manner rests in t is fact that pure sodium would at onoe he attacked by the electrolyte. The alloy of sodium and lead, however, is attached to a lesser degree" than pure sodium. Therefore by "thus alcsorhing the sodium as rapidly asit is separated by the current the loss by recombination is reduced to a minimum. The alloy is then carried toward the cathode by means of the circulating-pistons. The function of the lead is to act as a bipolar electrode in series with the primary electrodes, its surface, therefore, being negative acting as a cathode nearest the source of positive current and positive acting as an anode'nearest th source of negative current. It is, however, nossilole for the sodium to alloy with the lead, thus being able to pass through the lead, while the electrolytes have not this power. The function of the lead, in brief, is

to convey the sodium and the current from the anode to the cathode compartments While holding the electrolytes in their respective compartments. y

in the cathode-compartment the current decomposes the caustic soda, lil: "sting sodium at: the cathode 14 &Ild h:\ (il'OT;: l ions at the surface of the lead or secondar anode. The allinit between hydroxyl ions and sodium is greater than between hydroxyl ions and lead. Therei ore sodium dissolves in preference to lead and the caustic soda is reproduced. it will thus he seen that While caustic soda is constantly decomposhd there will be just as much remaining at the end of the i the salt decomposed in the anode-compartextinguishcd: hut the passage of a large current through the salt will continue to melt it secondary anode to the cathode. until the conmartment t. tilled to :h rc

ment. The caustic soda is then merely a medium for transferring the sodium from the The advantage oi separating sodium in this manner rests in the fact that it is liberated in an electrolyte free from the action of the oxidizing substances set free at the anode. This is made possible by the absolute separation of the electrolytes of the anode and cathode compartments by means of the molten lead. The lead thus performs the function of a semipermeable diaphragm, but with greater efficiency than the usual forms of diaphragnis, all other forms of which permit portions of the electrolyte, as well as the desired product, to .pass through.

The collection of the sodium liberated at the cathode has always been a matter of considerabie dilliculty in practice. One of the chief objects of this invention is to reduce these difficulties. The sodium collects upon the surface of the electrolyte 17, and therefore has a tendency to form bridges between the cathode 14 and the bell 13. In" case such a bridge is formed the current is short-circuited between the secondary anode and the cathode, and current thus lost will i produce no sodium at the cathode. To prevent this, the small iron pipe 18 is extended entirely around the bell just below the surface of the electrolyte. When cooling-water is passed through this pipe, the portion of electrolyte immediately surrounding the pipe will be solidified. This solid layer is a non-comluctor and will prevent stray currents from leaking across from the cathode to the bell, as well as prevent sodium bridges from coming in contact with the iron walls of the bell. The loss due to short circuits and stray currents is thus reduced to a minimum.

- The most serious source of loss, however, is

due to the oxidation of the sodium between the time it is liberated and its formation into I or hydrogen.

ingots. To exclude the atmosphere, use is made of the closed bell 13., This is kept filled with a gas which will not react to any great extent with sodium, such as nitrogen The sodium as it is liberated moves along the inclined surfaces of the cathodes to the overflow or draw-off pipes19, whence it isconveyed by iron pipes to a suitable vessel containing melted paraffin, below the surface of which the pipes dipl The sodium sinks to the bottom and can thus be collected without having been exposed to any oxidizing atmosphere at any moment from the time it was liberated till enough has collected to pour into the molds.

The circulating device for the lead is made as simple as possiblcto avoid the difficulty of making sliding .joints, which will remain tight through a great variation of temperature. instead of a. piston as ordinarily constructed use is made of pistons in the form of loosely-fitting lloats or plunger-s, which act merely by displacing a volume of load equal to the submerged volume of the piston. The load displaced by the downward movement of one piston is provided for by the si multaneous upward movement of the second. In flowing from one to the other cathodechamber the lead must pass beneath the anode-chamber and performs the alternate function of secondary cathode and anode, as already described. The lesser depth of the lead where it flows over the raised portion of the pan beneath the anode-compartment causes an increase in the velocity, thus removing the sodium more rapidly from the action of the anode electrolyte. The rate at which the pistons move is governed by the amount of sodium liberated in the anodechamber (thus on the number of amperes used) and the percentage of sodium which the lead can absorb with maximum efficiency. This percentage varies from four per cent. to six per cent. The lead may also be circulated by other means than the pistons, as shown.

' I do not wish to be confined to the production of sodium by my invention, as I may employ the invention for the production of any other metal which is lighter than the electrolyte from which it is separated, nor in the production of sodium do I wish to be confined to the use of pure common salt in the anode-compartment and pure sodium hydroXid in the cathode-compartments, as I may use some other salt or mixture of salts in one or both compartments.

What I claim as new, and desire to secure by Letters Patent, is

1. An electrolytic apparatus comprising an anode-compartment lined with refractory and non-conducting material, cathode-compartments at opposite sides thereof having interior metallic wall-surfaces, said compartments being supported with downwardlyopen ends above a body of molten metal which acts as a seal and also forms part of the electric circuit between the compartments, electrodes in the anode and cathode compartments, and means for producing a flow of the molten metal back and forth between the anode and the cathode compartments.

2. A11 electrolytic apparatus comprising an anode-compartment, cathode-compartments at opposite sides thereof, a pan containing a molten metal above which the compartments are supported with their downwardly-open ends sealed by said metal, said pan being shallow at the center beneath the anode-compartment and deeper at the ends, means for producing a flow of the molten metal back and forth between the anode and the cathode compartments, and electrodes in the anode and cathode compartments.

3. An electrolytic ap aratus comprising a pan resting over a iire- 0X at each end and having its bottom raised at the center, an anode-compartment supported over the pan with its downwardly-open end above said raised portion, cathode-compartments at opposite sides of the anode-compartment with their downwardly-open encis above the deeper portion of, the pan, a molten metal in the pan sealing the ends of said compartments, and means for producing a flow of the molten metal back and forth between the anode and I I said raised portion, eathodecompertments at opposite sides of the anode-compartment with their downwardly-open ends above the deeper portions of the pan, a molten metal in the pan sealing the ends of said compartments, riisplaeement-plungers at each end of the pan etheeentthe cathode-compartments, and means for reciprocating said plunger-s in opposite directions to produce e flow of the molten metal back and forth between the anode and the cathode compartments.

5. An electrolytic apparatus comprising anode and cathode compartments supported with their open ends downward and sealed by a molten metal, displacement-plungers acting upon said body of metal at oppositesides of the compartments, and mezms'fo reciprocating said plnngers in opposite Cl? tions.

6. In an electrolytic apparatus, nation, with an anode-come, cathode compartment colnprisin metallic bell said compartments ported with their open ends ilOWIP. Y .t sealed by a body of molten metal. 5

7. In en electrolytic apparatus e oath con'ipartment romprsing :2 closed bell, mi electrolyte contained therein, an eleotroele having its lower surface in Contact with surface of the electrolyte said surface of the electrode being inclined upward from the sides to the center and from one end t ward the other end, and e draw-oh" pipe having orifice at the surface of the ele trolyte adjacent the elevated end 01 the el node. 4

in testimony whereof the 1'' e 4: nature in presence of two wit COURTLAND F. oer-mien, JR; Witnesses:

M. VERBEOK,

A. S. DIVEN.

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