US2341244A - Electrolytic production of alloys - Google Patents

Description

W. w. SHROPSHIRE ETAL 2,341,244

INVENTORS Slvw M m L-l uzm ATTORNEYS unsuitable for discriminating use.

Patented Feb. 8, 1944 ELECTROLYTIC PRODUCTION OF ALLOYS William Wallace Shropshire, Chicago, and Amson L. Frohman, Calumet City, 111., assignors to International Smelting 8a Refining Company, New York, N. Y., a corporation of Montana Application July 11, 1939, Serial No. 283,832

4 Claims.

This invention relates to the production of .alloys, particularly lead-base alloys, and has for its object the provision of an improved method of producing alloys of leadwith metals having a substantially higher melting temperature than lead.

For certain applications, alloys of lead containing small amounts of such metals as copper, nickel, tellurium, silver and the like possess desirable properties and characteristics not found in substantially pure lead. For example, it is known that the addition of approximately .06% by weight of copper, to refined lead forms an alloy possessing greater tensile strength and greater resistance to certain types of corrosion than ordinary copper-free lead. It is also known that the addition of a small amount of nickel'or tellurium or silver or other metals or combinations of these metals to lead forms alloys having desirable characteristics for various applications.

The amount of the alloying metal which is required to impart to lead the desired beneficial properties is usually very small. Further, the desired advantages are not gained unless the alloying metal or metals is uniformly and thoroughly'dispersed throughout the mass of lead.

It is diflicult to produce an alloy by melting together metallic lead and one or more of the higher melting point metals. Where such a procedure is used, the metallic lead must be raised to an abnormally high temperature and the alloying metal or metals must'be added in a finely divided state. The alloys produced are usually not uniform in composition whiich renders them There is'also a large amount of oxidized material produced which must be retreated at additional expense.

Such lead base alloys are also made by chemical methods, whereby the metal or metals to be alloyed with the lead are contained in salts, which are added to the surface of a bath of molten lead. These methods depend upon the higher heat of combination or lead with the acid rad icles of the salts than the heat of combination of these acid radicles wtih the metal or metals of the addition salt. As a result of these salt additions, a chemically equivalent amount of the lead of the molten bath displaces the metal of the salt, which metal, reduced to the metallic state, alloys directly with the remaining bath of molten lead. The reaction precipitating the alloying metal is substantially a surface reaction surface of the bath of molten lead and the dispersion of the alloying metal throughout the bath of lead depends upon the extent to which the bath is agitated or stirred. The eventual uniform dispersion of the alloying metal or metals is therefore doubtful. The treatment is necessarily carried out at temperatures appreciably above the melting point of lead and substantial quantities of dross, which must be retreated, are produced.

We have discovered that such lead base alloys can be produced by electrical means without encountering the disadvantages generally continwith the whole of the alloying metal being precipitated at the plane of contact. The alloying metal or metals are thus concentrated at the gent upon the practice of the present art. The invention provides a method for the addition and dispersion of metals of higher meltingtemperature into and throughout a bath of molten lead at reasonable temperatures substantially below the melting temperatures of the alloying metal or metals. Based on this discovery the invention involves incorporating the alloying" metal or metals in the ionic state in a bath of molten lead by passing an electric current from an anode or anodes of the alloying metal or metals ,sub- T merged in a fused electrolyte through the fused; electrolyte to a bath of molten lead in contact with the fused electrolyte. Dispersion of the alloying metal so deposited in the bath of molten lead throughout the bath is conveniently eifected by appropriately stirring the molten metal.

In carrying out the invention, the,lead to be alloyed is melted and a suitable bath thereof is brought to the proper temperature. An anode or anodes of the substantially pure metal or metals to be alloyed with the lead is suspended in a suitable molten or fused electrolyte which is in contactwith the bath of molten lead. The

molten lead serves as a cathode. An E. M. F. is applied at the electrodes in such a way as to cause an electric current to flow from the anodes to the fused electrolyte and through the fused electrolyte to the molten lead cathode. As a result the alloying metal or metals are electrically corroded from the anode or anodes and deposited in the molten lead cathode. The electrolyte may be any fused salt of a metal and an acid characterized in that the metal of the salt is electropositive to the alloying metal or metals and the heat of formation of the metal of the salt and acid radical of the salt is equal to or higher than that of lead and the acid radical of the salt. When more than one metal is to be alloyed with the lead, the electrolytes must each conform to the foregoing characterization.

The single figure of the accompanying drawing diagrammatically illustrates an apparatus for the practice of the invention in itssimplest form. It is to be understood that any number of electro lyte compartments may be used, each compart merit employing a similar or dissimilar anode and consequently a similar or dissimilar elec= trolyte and the common molten lead cathode. For the purposes of explanation, the invention will be particularly described as applied to the production of an alloy of lead and copper, but it is to be understood that alloys of lead with any one or more of the higher melting point metals commonly associated with or miscible with lead may be equally well produced and with substantially the same advantages.

Referring to the drawing, the lead 3 to be alloyed is melted in a suitable not it and raised to a temperature of approximately 850 F. The pot 8 may advantageously be an iron kettle. The fused electrolyte 2 is held within a compartment formed by a vertically disposed open-ended iron cylinder ll lined with refractory concrete. However, the electrolyte compartment or compart ments may be constructed entirely oi refractory concrete or entirely of metal, and may be of any suitable shape. The cylinder 6 (r cylinders) is appropriately supported in a vertical position with its lower edge submerged from 4 to 8 inches below the surface of the bath of molten lead 3.

The cylinder (or cylinders) is of such a length I as to allow about 1.5 inches of length above the surface of the molten lead bath for each inch submerged in the molten lead. An anode i (or anodes) oi the metal (or metals) to be alloyed with the lead is appropriately suspended in the fused electrolyte (or electrolytes) in such a man nor as to permit vertical adjustment of the anode (or anodes) with respect to the molten lead cathode. The cathode connections may be made by an electrical connection 5 to the pot 8 or by means of an electrode 4 extending into the mol ten lead bath, or by both means. Where the pot 8 is an iron kettle, the cathode is preferably made to the kettle itself. The anode I (or anodes) and the cathode connections I or 5, or both, are electrically connected to an electric generator G, or other suitable source of electric energy.

In alloying copper with lead, the electrolyte is-preferablyiead chloride to which may-be added alkali metal or alkaline earth or other metal chlorides, such as, sodium chloride, barium chloride, zinc chloride and the like. Th function of the alkali metal or alkaline earth chlorides is to lower the melting point of the fused electrolyte and to increase its electrical conductivity,

The electrolyte is preferably fused outside of the cell and then added-to the electrolyte compartment b. However, the electrolyte may be melted by the heat of the molten lead bath 3 or by the resistance heat of the electric current. It is preferable to adjust the melting temperature of the electrolyte so that when passage of the electric current is stopped, the fused electrolyte will solidify while the metal in the pot remains molten. Thus the electrolyte compartment containing the solidified eleptrolyte may be lifted from the pot at the end of the operation.

At the start of the operation the metal anode I (or anodes) is adjusted so that it is approximately one inch above the molten lead cathode and is covered by the fused electrolyte (or electrolytes). The current from the generator G, or other suitable source of electric energy, is then started. The molten lead cathode is stirred connection from time to time by a stirring device I. It has been found that stirring from 30 to 50% of the time is sufiicient to effect uniform dispersion of the alloying metal ionically deposited in the molten bath of lead. The electrolyte 2 is maintained. in the molten or fused state by the resistance heat of the electric current and by the heat supplied by the molten lead cathode.

In alloying copper with lead in accordance with the invention using a fused electrolyte consisting largely of lead chloride, the following reactions take place:

Anode reaction: Cu+equivalent amount of electric current-*Cu+ Cathode reaction: Cu+-Cu+equivalent amount of electric current Electrolyte reaction:

-Cu anode Cu+l I Cl- Pb cathode As a result of the anode reaction, cuprous chloride is formed at the a Immediately p being formed the cuprous chloride is dissociated into metallic copper ions which migrate to the cathode and chlorine ions which migrate to the anode. After the initial anode reaction, the cuprous chloride, due to its lower decomposition voltage, becomes the real supporter of the electrolysis, and the process continues so long as the electric current is allowed to flow. The alloying metal or metals, copper in this instance, travels to and is deposited in the molten lead cathode in the ionic metallic state. The electrolyte is regenerated, and all actions are simultaneous and continuous.

'The only raw materials used in the process are the cathode lead to be alloyed and the anode metal or metals to be alloyed with the lead. Since the electrolyte is regenerated, it may be used continuously and repeatedly. The following examples illustrate practices of the invention:

Example Example #1 #2 Cathode metal to be alloyed (Pb) wt. lbs 9, 710 9, 848 Average amperage. 70. 40 14 29 Average voltage 1. 84 3. 37 Time of electrolysis, hours 2p. 5 8. 66 Electrochemical equivalent, monovalcnt Cu gms. 11 per amp. hr.) 2. 3717 2. 3717 Copper deposited in lead, actual wt. lbs. .7..-l8 6.18 Copper deposited in lead, theoretical wt. 7. 54 6. 58 Ampere efiicioncy, per cent 95. 4 93. 94 Dross formed during treatment, wt. lbs 40 30 Cathode metal temperature range, degrees R. 820-920 Electrolyte temperature range, degrees F 740-840 720-780 Electrolyte No. 1 No. 2

per cent" 60 ZnClz do 20 25 NaCh d 10 15 Analysis of metal before electrolysis Cu Nil Nil Analysis of metal after electrolysis Cu 074 062 The practice of the invention requires very little attention. The ampere efilciency is sub-- trol necessary for operation is a suitable instrument for measuring the amperage.

The alloying metal or metals are deposited-in the molten lead as ions of the metal rather'than as particles, thereby making possible a better The cost of thealloying metal added to the lead is substantially less when used in the metallic form than when obtained from a salt or compound of the metal. For example, when copper is to be added to lead the cost of the copper in metallic form as employed in the practice of the present invention is considerably less than when obtained from copper salts, such as copper chloride or copper sulphate, as heretofore commonly employed in the production of alloys of lead and copper; The invention thus effects a substantial economic saving.

While we have hereinbeforeparticularly de-' scribed the addition of copperto lead inorder to illustrate the electrolytic method of the invention, it is to be understood that one or more of the high melting point metallic elements such as copper, nickel, silver, tellurium, etc., may be alloyed alone or 'at the same time with the lead I with equal facility. When one or more additional metals are to' be alloyed with the lead, the apparatus may consist of multiple electrolyte compartments and multiple anodes of the metals to be added. In this case, the electrolyte compartments may contain similar or dissimilar electrolytes as required by the particular anodes emmay thus be produced in a single operation or in one or more successive separate steps using the alloy from a previous operation as the cathode in the succeeding operation.

We claim: V 1. The method of producing an alloy of lead and a metal having a substantially higher melting point than lead which comprises incorporating the alloying metal into a molten bath of lead by electrolytically transferring the alloying metal-from a solid anode thereof submerged in a fused electrolyte to a cathode consisting of. the molten bath of lead, said fused electrolyte conhigh as that of lead and the acid radical of the salt.

2. The method of producing an alloy of lead and a metallic element of the group consisting of copper, nickel, tellurium and silver which comprises incorporating the alloying metallic element into a molten bath of lead by electrolyti ployed. Alloys of one or more metals with lead v cally transferring the alloying metallic element from a solid anode thereof submerged in a fused electrolyte to a cathode consisting of the molten bath of lead, said fused electrolyteconsisting essentially of a salt of a metal and an acid characterized in that the metal of the salt is electropositive to the metallic element to be alloyed with the lead and the heat of formation of the metal and the acid radical of the salt is at least as high as that of lead and the acid radical of the salt.

3. The method of producing an alloy of lead and copper which comprises ,incorporating the copper in a molten bath of lead by electrolytically transferring the copper from a solid anode thereof submerged in a fused electrolyte consisting essentially of lead chloride to a cathode consisting of the molten bath of lead.

4. The method of producing an alloy of lead and atmetal. having a substantially higher melting point than lead which comprises-incorporating the alloying metal into a molten bath .of lead by electrolytically transferring the alloying metal from a solid anode thereof submerged in a fused electrolyte to a cathode consisting of the molten bath of lead, said fused electrolyte consisting essentially of a salt of a metal and an acid characterized in that the metal of the salt is electro-. positive to the metal to be alloyed with the lead and the heat of formation of the metal and the acid radical of the salt is at least as high as that of lead and the acid radical of the .salt, and incorporating a second metal having a substantially higher melting point than lead in a molten'bath of the alloy of lead and the first-V trolyte to a cathode consisting of the molten bath of alloy of lead and the first-mentioned alloying metal.

WILLIAM WALLACE SEROPSHIRE. AMSON L. FROHMAN.

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