US1938101A - Metal refining process - Google Patents

Description

Dec. 5, 1933. A. E. HALL METAL REFINING PROCESS Dec. 5, 1933. A. E. HALL METAL REFINING PROCESS Filed Aug. 11. 1931 3'. Sheets-Sheet 2 M5 ma n TH VN N. R WF. mw m m AY .B

Dec. 5, 1933. A. E. HALL METAL REFINING PROCESS Filed Aug. 11, 1931 l5 Sheets-Sheet 3 INVENTOR ,4r/har E Hal/ BY M JM ATTO NEYS Patented' Dec. 5, 1933 UNITED STATES PATENT OFFIC 16 Claims.

This invention relates to metal refining and is more particularly directed to a process for the partial or complete removal from lead of various other metals.

Most metallic alloys or mixtures of two or Amore metals (including alloys and mixtures containing so-called earth metals like calcium and alkali metals like sodium) when cooled from a complete molten state to certain temperatures yield a portion in solid state and a portion in molten state, which portions differ in composition on account of partial concentration of one or more of the constituent elements in one of such states. Among such alloys or mixtures to which this invention is directed are the combinations of two or more of the following metals, lead, silver, antimony, tin, copper, arsenic, bismuth, cadmium, magnesium, calcium, sodium and zinc. Many of the alloys of these metals have melting temperatures below 800 C. and'can be mixed, separated and treated in ordinary cast iron containers.

This application is a continuation in part of my co-pending application Ser. No. 405,573, filed November 8, 1929.

The proportions of the metals When combined with one another alter the properties of the resulting product to a greater or less extent dependent upon the relative amounts of the metals present.

The metal bismuth is found as an impurity in lead and when present in even small quantities, say upwards of 0.15%, renders the lead unsatisfactory to a large portion of the lead consumers. Cable sheathing, lead pipe, sheet lead, battery plate grids and lead for paint making purposes and other purposes will not tolerate lead containing even small quantities such as 0.15%. If n the bismuth content is reduced to 0.034% or f3 less the lead produced is satisfactory to the trade.

At the present time it is possible to produce lead containing such low quantities of bismuth by the electrolytic process of refining, and by segregating ores, but the electrolytic process is an alittle less than 1 per pound for such treatments.

Antimony is employed with lead in storage batteries. These batteries contain elements having about 3% antimony and 97% lead. Other, elements contain about 8% antimony and 92% lead, and the batteries also contain pure litharge made from pure lead. 'I'he litharge has little or no antimony in it. There have been many proposals for treating scrap batteries, but none seems suitable for the production of lead and alloys for manufacture of new batteries. All require obtaining pure lead and lead antimony alloys in addition to the scrap batteries. For example some battery manufacturers buy scrap batteries 6 and smelt them, getting a product which is slightly over 4% antimony and 96% lead. To this they add materials as mentioned to give the requisite antimony content as above and then buy their pure lead on the market. This proc- 70 ess, however, has the disadvantage that the cost of producing the necessary alloys and lead is raised because of the necessity of purchasing such materials from outside sources and also because certain by-products are produced which are diicult to dispose of.

In the refining of lead containing antimony the former practice was to produce a by-product containing about 86% lead and about 14% antimony which was salable and could be used by the trade. When the Harris process for refining appeared, attempts were made by refiners, other than those employing the Harris process, to produce a more pure lead from this material and it was found that refining and production of more pure lead in this y Way could be accomplished. However, the byproduct obtained from this refining contained about 30% antimony and 70% lead and has not found a ready sale. There is accordingly a demand for a process which can satisfactorily handle such material to make more salable products. In addition secondary metal dealers are under contract to furnish bearing metals, stereotypes, solders, die casting metal, etc. The raw material does not always produce the proper proportions of metals and these proportions have to be made 9D up by purchase of metals on the outside.

In 1900 Stephen Tredinnick who had been working at a plant in Nevada Where the separation of silver from lead was being practiced, was granted a U. S. Patent No. 662,836 for an Apparatus for refining and desilverizing lead, and somewhat later it was attempted to employ the appartus described in his patent for the removal of bismuth from lead and the concentration of the bismuth in a relatively small amount of lead. The apparatus involved included a number of kettles which were separately heated and agitated in an attempt to insure uniform heating throughout by blowing steam into the .kettles. After heating up of a charge in one kettle, it was allowed to crystallize in part and the kettle was then lifted by a hydraulic ram and the molten contents were allowed to flow into a second and adjacent kettle, after which the remaining crystals were melted in the rst kettle and then, this kettle still being elevated by means of the hydraulic ram, the melted crystals were transferred by gravity to a third and adjacent kettle. The process was not a continuous one and involved a large percentage of idle equipment containing metallic lead whose processing was awaiting the release of other apparatus in the refining group. The apparatus also presented considerable other difficulties in operation which resulted in a relatively small out put and an exorbitant cost along with poisoning of the operatives due to the production of fine particles of dross blown up by the steam used in agitation of the kettles. These disadvantages resulted in abandonment of the Tredinnick apparatus for the purpose mentioned and since then it has been necessary to rely on the costly and laborious electrolytic process.

The principal object of this invention accordingly is to produce a simple, inexpensive, and efficient process for refining lead to uniformly control the content of one or more of the other metals mentioned above therein. Another object of the invention is to provide a simple efficient process which shall permit a continuous separation of such metals from one another, which shall avoid holding large masses of metal idle while waiting for available apparatus for processing, which shall permit a simple effective control to be maintained for the production of metal containing desired percentages of other metals and in accordance with the content of other metal in the raw material as received. Specifically in connection with the separation of bismuth from lead, an object of the invention is to do away with the disadvantages of the costly electrolytic process and to overcome those described in the practice of the Tredinnick process. Another object is to provide such a process for treating lead-antimony to produce the required metal for storage batteries without purchase of outsidemetal.

'Ihe invention accordingly comprises the novel processes and steps of processes, specific embodiments of which are described hereinafter by way of example and in accordance with which I now prefer to practice the invention.

Further and more specific objects, features and advantages will clearly appear from the detailed description given below taken in connection with the accompanying drawings which form a part of this specification and illustrate an example of an apparatus which may be used for the carrying out of the process.

In the drawings, Fig. 1 is a diagrammatic plan view of the apparatus, the driving shafts for crystals conveyors and certain other parts being omitted for the sake of clearness;

Fig. 2 is a corresponding diagrammatic elevation thereof;

Fig. 3 is a detail sectional elevation taken on the line 3-3 of Fig. l, showing the crystallizer with a spiral conveyor and its driving means moving crystals out of the molten bath, these crystals being deposited in a heated kettle onthe right;

Fig. 4 is a diagrammatic end elevation of the series of crystallizers and kettles;

Fig. 5 isa sectional plan view of a part of the series of crystallizers, and kettles taken on the line 5-5 of Fig. 3, certain parts being omitted for the sake of clearness; and

Fig. 6 is a sectional elevation taken on the line 6-6 of Fig. 5.

In the description of my invention which follows below. I have described the apparatus in connection with the separation of lead and bismuth for convenience. Other separations such as lead from antimony, lead from tin, etc. may be similarly carried out in accordance with this process.

Referring now to the drawings, and particularly to Figs. 1 and 2, I have designated a series of crystallizers or baths there shown as C1 and C13 inclusive and the kettles corresponding thereto and into which each crystallizer or bath delivers to K1 to K13 respectively and inclusive. These crystallizers and kettle units constitute a series at one end of which, namely at K1, lead of the lowest bismuth content produced is obtained and at the opposite end of the series lead with the highest bismuth content is obtained.

These crystallizer-kettle units, C1, K1, C2, K2, C3, K3 and so on are positioned so as to maintain therethrough a continuous and unobstructed gravity flow of lead-bismuth in which the bismuth is increasing and an opposite flow which is partially by gravity of lead-bismuth with increasing content of lead. To accomplish the gravity flow, each crystallizer, for example C1, is set at a height, preferably 6 inches, above the next crystallizer C2 in the series. In accordance with this arrangement, the metal level of C2 is at a height of 6 inches higher than the metal level of C3, and the metal level of C3 is at a height of 6 inches higher than the metal level of C4, and so on through the series. Between each crystallizer or bath is a substantially horizontal open launder serving to convey molten lead-bismuth alloy from one crystallizer or bath to the next by gravity due to the head existing between the crystallizers, thus between Cl and C2 is a launder L1, between C2 and C3 is a launder L2 and so on throughout the series of launders L3 to L12 occur, L12 being positioned between crystallizer C12 and C13 and a launder L13 serving as an exit for the lead containing higher bismuth.

The ow of lead-bismuth alloy in which the amount of lead is increasing is maintained by continuously rotating screws and partially by gravity. Each of the crystallizers is provided with respective screws S1 to S13. These screws are of a particular construction which will be described hereinafter. The crystallizers or baths are maintained at a suitable temperature to keep a molten mass of combined lead and bismuth with crystals of lead-bismuth, which crystals will naturally contain less bismuth than the bismuth content of the molten mass, and correspondingly more lead. The proportion of lead-bismuth crystals to molten metal in the bath will be maintained at a ratio which will give desired results. I find 57% crystals and 43% molten metal maintains proper grades in the case where the raw material containing 0.164% bismuth is charged into K6 when a product from K1 is desired containing 0.034% bismuth, but other grade"J of raw material and other desired grades of products may indicate other proportions.

The crystals are moved out of the crystallizer or bath by the rotating screws,-each screw delivering into its corresponding kettle at a pre\;lster` mined rate depending upon the area of the rew and of course upon the proportion of crystals to molten metal present as determined by the temperaure maintained. In each kettle the crystals received are melted by an oil burner or other source of heat and in melted condition are allowedpto flow by gravity through a series of open ducts or launders D1 to D12 inclusive. 'Ihe duct leading from the kettle K2 to crystallizer C1 is designated as D1, from the kettle K3 to C2 is designated as D2 and so on to the end of the series. The duct D13 leads from the kettle K1 and is an outlet for the lead containing the lowest content of bismuth. The launders L1 to L12 inclusive and the ducts Dl to D12 inclusive are so positioned that the hot gases issuing from the combustion chambers of the respective oil burners under the respective kettles in part or in whole surround the launders and ducts to prevent chills and stoppages in same.

A typical crystallizer and kettle construction is shown in Fig. 3. The crystallizer and kettle there shown are those designated in Figs. 1 and 2 as C6 and K6. The crystallizer is in the form of an open trough of suitable material such as cast iron mounted in a base 1 of concrete or other suitable material. The bottom 2 of the crystallizer is inclined at anangle of about 90 to the lower end wall 3 o f the crystallizer and the bottom wall is set at about an angle of 40 to the horizontal being held in position by the concrete base 1. Mounted in suitable bearings on the end walls is a rotatable shaft 4 which is rotated by an outside source of power not shown, which outside source of power rotates corresponding shafts to which each of the respective screws S1 to S13 are attached. The screw S6 there shown is attached to shaft 4 and is in the form of a helix being perforated throughout with draining holes 5 about 1% inches, preferably,v in diameter. The bath of lead-bismuth 6 contains approximately the ratio 57% crystals to 43% molten mass and the screw 6 as it rotates moves these crystals out of the molten bath, draining back any molten material through the perforations 5, the crystals being deposited in the kettle K6. The kettle K6 is mounted on suitable pillars of refractory material 7 and is surrounded by a refractory fire wall 8 through which an oil burner 9 for supplying heat to the kettle K6 is provided. The crystals passing into the kettle K6 are melted there and then flow back through the duct D5 into the crystallizer C5. The temperature of the molten crystals in K6 is maintained so that when these crystals reach C5 they will be at the proper temperature to maintain a ratio of crystals to molten material of the desired 57% crystals to 43% molten material or any desired proportion. This temperature is maintained by suitable regulation of the heat provided by the oil burner 9.

The arrangement for heating the upper portion of the crystallizers is shown in Figs. 5 and 6. The description of one heating means for a crystallizer will suce for all as the heating means is preferably identical throughout. As shown in Figs. 5 and 6, the gases passing from the burner 9 pass under the kettle K6 and up through two ducts 10 and l1 at the end of 'the kettle on either side of the crystallizer. These ducts are controlled by hand-operated dampers 12 and 13 to allow part or all of the gas to pass upwardly without paing around the crystallizer C6 or else part or substantially all of the burner gases may pass along the side walls of the crystallizer in order to heat that part of the crystallizer above the level of the lead therein. For this purpose openings 14 and 15 are provided respectively in the ducts 10 and 11 at a. point between the lead level in crystallizer C6 and the top of the crystallizer tank. This duct leads respectively into flues 16 and 17, each of which is shaped to follow the outline of the crystallizer wall above the lead level.` At the end of the crystallizer away from the ducts 10 and 11 the ues 16 and 17 are attened out as shown in Fig. 5 joining one another to make a flattened flue 18 which communicates by a branch 19 with a common pipe 20 leading to the stack 2l. Gases from flues 10 and 11 after passing therethrough may also be led to the stack 21 by connections not shown.

Dampers 12 and 13 are provided with handles so that they may be moved in the ducts 10 and 1l and positioned to cause all of the gases to pass up the conduits 10 and 11 when it is not desired to heat the upper part of the crystallizers or to divert part or all of the gases along the flues 16 and 17 to heat the upper part of the'crystallizers desired.

Each of the ilues 16 and 17 has a crystallizer wall forming one vertical side of it in each case, the other walls of the ilues as well as the walls of the ducts being made of suitable refractory material. These heated flues serve the purpose of preventing solid chills on the inner side of the wall above the molten metal level thereof. Such chills are to be avoided because they not only impede the rotary movement of the screws bui cause a solid lead bismuth compound to form which may be different from the constitution oi the crystals in the crystallizers.

Each of the screw conveyors S1 and S13 is driven in a manner similar to that shown with the screw conveyor S6 in Fig. 3. A common shaft 22 drives the various screw conveyors. A tooth pulley 23 is mounted opposite each crystallizer tank communicating through a chain 24 with tooth pulley 25 mounted to drive a worm 27 mounted on the crystallizer and driving a worm wheel 28. The latter is mounted on the end of the shaft 4 of the screw conveyor S6. I preferably .maintain the revolutions per minute of all screw conveyors the same. Once started the speed of these conveyors need not be adjusted. The rate of crystal delivery into the kettle is controlled as heretofore pointed out by the temperature maintained in the crystallizers and hence the quantity of crystals produced. This temperature is adjusted by means of the oil burners underneath the various kettles and control of the plant by control of the heat supplied to these burners so that a greater or less tonnage to be-produced at the ends of the series is secured.

The typical crystallizer and kettle shown in Fig. 3 is repeated in each of the other crystallizers and kettles represented in the group Cl to C13 inclusive and Kl to K13 inclusive, includingr the inclination of the crystallizer, the form of the conveyor, positioning of the kettle and the oil burner, ducts and flues for adjusting the temperature thereof.

As shown particularly in Figs. 1 and 2, the respective diameters and areas of the kettles, crystallizers and screws vary, the larger ones being on the left and being graduated to the smallest on the right of the series. This graduation is arranged proportionately to the amount of work done by each unit.

The overflow levels for the various crystallizers for crystals being moved into the respective kettles are designated respectively as Cl to C13 in clusive, see particularly Fig. 4.

Process for separating lead and bismuth In carrying out the process of separating lead from bismuth, lead containing bismuth in the proportion of .164% as an example, is available as a starting material and is employed in the process although it will be understood that lead with higher or lower bismuth contents may be employed to commence the process. This material is melted and charged into the crystallizer C6 where it attains a temperature such that the mass will contain approximately 57% of lead'- bismuth as crystals and about 43% of molten material, approximately 317 to 327 C. The screw conveyors Sl to S13 are started to rotate and the oil burners for kettles K1 to K13 are started to bring the temperatures in these various kettles up to the proper points, all of the crystallizers having been brought to and being maintained at a suitable temperature for providing the desired ratio of crystals to molten material therein as received. The crystals are continuously transferred from the crystallizer into the melting kettle K6 which is now at a suitable temperature to melt the crystals whereupon they ilow through D5 into crystallizer C5 which is at a suitable temperature to maintain the ratio of crystal to molten condition of 57% to 43% or any desired ratio. The screw conveyor there removes these crystals as they form and moves them into the kettle K5 where they are melted. The molten material in C5 due to the position of C5 above C6 tends to ilow and in part flows through L5 back into C6 where it joins molten material already there. C6 is maintained by the molten metal ilowing from K7 and also by the heated gases from the combustion chamber of K6 at a slightly lower temperature than C5 where temperature is maintained by inilowing molten metal from K6 and also by regulated diversion of heated gases from combustion chamber of K5 so that from the molten material flowing from C5 to C6 through L5 some crystals form and these join crystals forming from molten material already present in C6 and these combined crystals are moved as indicated by S6 into the kettle K6. C6 is supplied, of course, it will be understood by fresh lots of the raw material containing bismuth of approximately 164%. The molten material in C6 will tend to ilow from it to C7 due to the height of C6 above C7. C7 is maintained at slightly lower temperature than C6 and crystals form therein. these crystals being removed by S7 into K7. In K7 a similar process to that occurring in K6 results and K7 being 6 inches higher than C6 the melted crystals flow back into C6. The molten material in C7 passes through L7 into C8. The crystals of lead-bismuth containing a higher content of lead are those flowing by combined screw action and gravity in a direction towards K1 from which the material lowest in bismuth and highest in lead is obtained. The lead containing bismuth is fed in molten condition from a tank T which may be connected to any one of the intermediate kettles. In this case it is shown as connected to K6 (see Fig. 1) and is intended to supply as there connected, lead containing preferably a bismuth content of about 0.164%. If lead with a lower bismuth content were supplied this tank could be connected to kettle K4, K3, or ii' lead with a higher bismuth content were supplied the v. tank could be connected to K7, K8 etc. Tank T gravity as I prefer from C1 to C2, from C2 to C3 and so on through the series, C1 to C13 having successive degrees in bismuth content of .05% to 2.00% in the same stages just mentioned but in the reverse direction.

On the other hand the molten material is flowing entirely by gravity as I prefer, through the series K13 to C12, K12 to C11, and so on from K13 to K1 to ilnal product issuing from K1 of a grade of 0.034% bismuth, according to the stages first mentioned. The crystals collected in K1 therefore will have a bismuth content of approximately 0.034% or less and a lead content of approximately 99.9%

On the other hand the molten material containing the higher contents of bismuth is ilowing entirely by gravity, as I prefer, through the series of kettles from K1 to K13 with a bismuth content increasing from .042% to 1.460% bismuth, according to the stages just mentioned, in the reverse direction.

It will be understood that although I have shown and described in the specification the production of a lead containing 2.00% of bismuth, the content of bismuth in the product passing from C13 may range to higher percentages of bismuth towards that alloy of lead and bismuth which has the lowest melting point and contains a higher percentage of bismuth.

Process ,for separating lead and antimony Example 1.-The process of separating lead from antimony may be carried out similarly to the above. Material containing 72.8% lead and 27.2% antimony is available as a starting material and is employed in the process although' it should be understood that lead with a higher or lower antimony lead content may be employed to commence the process. My intention in operating the following example of the process was to produce an antimony lead product containing about 12.5% antimony and 87.5% lead and another product containing about 82% antimony and about 18% lead. In order to do this I found it necessary to use only three crystallizer-kettle units. I found in operating the following process that crystals with high antimony content separating out in the bath of molten liquor are of lower specific gravity than the liquor and therefore float thereon. If the screws S1 etc. are entirely submerged the antimony crystals tend to accumulate at the vlower end of the crystallizers Cl, C2, etc. and are not moved upward as intended. Because of this characteristic of the antimonycrystals, I employed screws of four inches in diaml.

eter with a clearance between the screw and the side of the crystallizer of 3% inch. The crystallizers were arranged at an angle of 30 to the horizontal.. The overflow liquids were established so that the screw was only two-thirds submerged at the lower end of the trough and no holes were drilled in the ights of the screws. On the rst unit diversion plates are introduced fora few inches up from the lower end of the trough fitting the exposed edges oi.'` the screw flights to insure upward and forward movement of the crystals. The screw is operated at 30 revolutions per minute.

The material containing 27.2% antimony and 72.8% lead is melted and charged into the kettle K2. When kettle K2' becomes full it overilows into crystallizer C1. This crystallizer C1 is maintained at about 265 C. A proportion of about 17% of lead-antimony crystals and about 83% of molten material is maintained in C1 at the temperature mentioned. The screw conveyors S1 to S3 are started to rotate and the oil burners for kettles K1 to K3 started to bring the temperatures in these kettles up to the proper points. The temperatures are arranged so that the temperature in Crystallizer C1 is maintained at or about 265 C., the temperature in Crystallizer C2 is maintained at or about 255 C. and the temperature in Crystallizer C3 is maintained at or about 248 C. The ratio of crystals `to molten material in each of the crystallizers C1 to C3 is as given above for Crystallizer C1, namely about 17% of crystals to 83% of molten material. The crystals are continuously transferred from the crystallizer C2 into kettle K2 which is now at a suitable temperature to melt the crystals whereupon they :How through D1 into Crystallizer C1 which is at a suitable temperature to maintain the ratio of crystals to molten condition of 17% to 83% or any desired ratio. The screw conveyor there removes these crystals as they form and moves them into the kettle Kl. The molten material in crystallizer C1 due to the position of C1 above C2 tends to flow and in part ilows through launder Ll back into C2 where it joins molten material already there. C2 is maintained by the molten metal owing from K3 and also by the heated gases from the combustion chamber of K2 at a slightly lower temperature than Cl, where temperature is maintained by inowing molten metal from K2, and also by regulated diversion of heated gases from combustion chamber of K1. Accordingly from the molten material flowing from C1 to C2 through L1 some crystals form and these join crystals forming from molten material already present in C2 and these combined crystals are moved as indicated by S2 into the kettle K2. As pointed out molten material containing 27.2% antimony and 72.8% lead is furnished from tank T to the kettle K2 continuously.

The molten material in C2 will tend to ow from it to C3 due to the height of C2 above C3. C3 as noted is maintained at a slightly lower temperature-248 C.-than C2, and crystals form therein, these crystals being removed by S3 into K3. In K3 a similar process to that occurring in K2 results and K3 being six inches higher than C2 the melted crystals flow back into C2. The molten material in C3 passes through L3. L3 is in this instance the launder through which the discharge of high lead-content material is passing while the discharge from K1 through duct D13 is of high antimony-content material. I found when Crystallizer C1 became full and operating at 265 C. it was discharging into kettle K1 crystals containing 82% antimony and 18% lead, which crystals were then melted and passed out of D13 with such content. Crystallizer C1 was discharging into crystallizer C2 liquid containing approximately 20% antimony and 80% lead. When crystallizer C2 became full and. was operating at 265 C. it was discharging into kettle K2 crystals containing about 27% antimony and about 73%'1ead (viz. about the same as the melted raw material charged into tank T). Crystallizer C2 was also discharging into crystallizer C3 liquid containing about 15% antimony and about 85% lead. When Crystallizer C3 became full and operating at 248 C. it was discharging into kettle K3 crystals containing about 20% antimony and about lead. Crystallizer C3 was discharging through launder L3 liquid containing about 12.5% antimony and about 87.5% lead. It will be noted that the direction of ilow of the higher content lead in this case is the opposite from the direction of ow of high content lead in the purication of lead-bismuth.

In operating the apparatus the raw material is continuously charged into kettle K2 at a proper rate to maintain the requisite flow through the apparatus. With the apparatus employed as described I found this rate was about 80 pounds per hour.

It is apparent that in the above process crystallizer- kettle units 2 and 3 are scavenger or clean-up units". As operated they produce the alloy of antimony and lead having the lowest melting temperature. From alloys of lead and antimony containing over 12.5% antimony when cooled down to 248 C. only pure antimony crystallizes out but these crystals mechanically entrain the residual mother liquor. The scavenger or clean-up units were required to offset this tendency. It was not determined how pure antimony vcrystals could be produced by this apparatus alone. Screening out the lead globules from dry, cold antimony crystals thus produced gave a product with 87% antimony.

Example 2 The following is an example dealing with the problem of conversion of scrap lead storage batteries, manufacturing scrap, and drosses into primary materials for making up new batteries. As pointed out above new batteries contain certain portions of antimony and lead as follows:-

1. Antimonial lead containing 2% to 4% antimony;

2. Antimonial lead containing 5% to 9% antimony;

3. Oxides made from pure lead.

In producing the starting material for the operation of my process, I smelted scrap batteries including terminals, connectors, grids and paste and also some manufacturing dross and scrap, according to a well-known process for such smelting, and produced metal containing 3.6% antimony and 96.4% lead.

In this instance I operated eleven units producing at one end of the apparatus metal containing 99.6% lead and 0.4% antimony and at the other end of the apparatus material containing 9% antimony and 91% lead.

The units were operated in the same manner as heretofore indicated for the lead bismuth and lead antimony separation except that the temperature maintained varied from 324 C. in crystallizer C1 to 264 C. in Crystallizer C11. The raw material in melted condition containing 3.6% antimony was charged into kettle 9K. Crystallizer C1 discharged crystals containing 0.4% antimony and 99.6% lead which in molten condition were discharged through duct D13. Crystallizer C11 discharged liquid through launder L11 containing about 9.0% antimony and 91.0% lead. 4" diameter screws were employed andraw material was discharged into kettle K9 at the rate of about 120 pounds per hour. Analysis showed the average composition of mate- It is apparent that desired proportions of 2% to 4% antimony, of 5% to 9% antimony and 0.4% or less antimony are thus produced. While it is quite possible to continue the elimination of antimony below 0.4% yet it probably is not practicable to thus produce pure lead. Hence for the oxide production this nearly pure lead, containing 0.4% antimony or less would be subjected to a slight oxidation process before oxide manufacture. The'small amount of bi-product from such an oxidation process would be added to the smelting charge of the original scrap.

Storage batteries contain lead-antimony alloys and pure lead oxide containing proportions of lead and antimony about as follows:-

1. 2% to 4% antimony, 96% to 98% lead;

2. 5% to 9% antimony, 91% to 95% lead;

3. Pure lead oxides and rened lead.

It is therefore apparent in operating as above it is possible for the manufacturer to convert scrap batteries, dross, etc., into material from which can be made up the entire new battery without the purchase on the outside of pure lead or antimonial lead.

There are innumerable well-known and desirable separations by fractional crystallization in the series of lead-tin-antimony-copper alloys and other metals heretofore mentioned. It will be understood that although I have shown and described certain specic separations of metals, the apparatus and manipulation is applicable to all l combinations of the metals mentioned in those cases where fractional crystallization effects desirable separations. The advantage of simultaneously working up 4all intermediate products is obvious.

The process is continuous and eliminates delay in the units. There is no mass of molten material waiting for a kettle or crystallizer to be free before it can be processed. After the temperatures have been adjusted throughout the units the process can be operated without change of temperature in the units as long as the raw material being supplied contains about the same quantity of metals other than the major metal, as long as it is desired to produce end products of approximately the same metallic content. One advantage resulting from the maintenance of a uniform temperature is that it is not necessary to cool down or heat up large masses of refractory material which are naturally poor conductors, radiators and absorbers of heat. The process is applicable of course to materials with varying antimony-bismuth and other metal contents and in accordance with the temperature control, the poundage or tonnage, issuing from either the low antimony-bismuth or other metal end or the high end may be adjusted. The desired flow of metal, namely major metal concentrate in one direction is automatically obtained by reason of the established levels of the crystallizers and kettles and flow in any other direction is prevented. When the process is employed for the treatment of scrap batteries, it provides a simple and efficient method for changing these batteries into materials from which new parts with the desired content of antimony may be prepared without purchase of lead or lead-antimony alloys outside. The process therefore permits a considerable saving in time and money as compared with older processes'where such conversion could not be practised.

While I have described my invention in considerable detail and with respect to a preferred form thereof, I do not desire to be limited to such detailsor form since many changes and modications may be made and the invention embodied in widely different forms without departing from the spirit and s cope thereof in its broader aspects. Therefore, I desire to cover all modifications and forms coming within the language or scope of any one or more of the appended claims.

What I claim as new and desire to be secured by Letters Patent is:

1. A process for rening a mixture of two or more metals which comprises crystallizing a molten bath containing two or more of the metals lead, antimony, tin, silver, copper, arsenic, bismuth, cadmium, magnesium, calcium, sodium, zinc to obtain crystals of at least two of said metals, said crystals having a higher content of one metal than the content of that metal in said bath, removing crystals so formed from the molten bath and continuously supplying a molten mixture containing the metals of said crystals, but having approximately the same metal content thereof as in the bath and drawing oft' a mixture' having a lower content of one of said metals than found in said bath.

2. A process for rening a mixture of two or more metals which comprises maintaining the temperature of a molten bath containing two or more of the metals lead, antimony, tin, silver, copper, arsenic, bismuth, cadmium, magnesium, calcium, sodium, zinc, at a. point to obtain a proportion of crystals of at least two of said metals with an increased content of one metal as compared with the content of said one metal in the molten bath, and continuously removing the crystals so formed from the molten mixture.

3. A process for rening leadto remove other metal therefrom, which comprises, crystallizing a molten bath containing lead and another metal to obtain crystals of lead and the other metal with an increased lead content, removing crystals so formed and supplying a molten mixture of lead and the other metal of approximately the same lead content as the bath, and drawing oif a portion of the molten bath containing the lead and other'metal.

4. A process for refining lead to remove other metal therefrom, which comprises, crystallizing a molten bath containing lead and one or both of the metals antimony and bismuth to obtain crystals of lead and at least one of said other l'su bath and drawing o a portionfbf the lead and at least one oi' said other metals of`a lower lead content than the remainder of the bath. i

5. A process for refining lead to remove bis muth which comprises, continuously removing crystals formed in a lead-bismuth bath as they form while maintaining the composition of the bath approximately the same throughout.

6. A process for refining lead to remove bismuth which comprises, maintaining the temperature of a lead-bismuth bath at a point to obtain a proportion of crystals of lead-bismuth with an increased lead content in a molten lead-bismuth mixture, and continuously removing the crystals as formed from the molten mixture, while keeping the crystals and molten mass agitated.

'7. A process for separating lead and bismuth which comprises crystallizing a lead-bismuth bath to obtain crystals of lead-bismuth with an increased lead content, removing crystals so formed, and continuously supplying a molten lead-bismuth mixture of approximately the same lead content as the bath and continuously removing molten lead-bismuth containing a somewhat lower lead content from the said bath.

8. A process for separating lead and bismuth which, comprises crystallizing a lead-bismuth bath to obtain crystals of lead-bismuth with an increased lead content, continuously removing crystals so formed, supplying thereto a molten lead-bismuth mixture of approximately the same lead content as the bath and removing molten lead-bismuth containing a somewhat lower lead content from the said bath, while keeping the crystal and molten mass agitated.

9. A process for separating lead bismuth which comprises crystallizing a lead-bismuth bath to obtain crystals of lead-bismuth with an increased lead content, transferring the crystals so formed continuously to a molten lead-bismuth bath of va somewhat higher lead content than the bath from which they came, continuously supplying molten lead-bismuth residual from crystallization from the second-mentioned bath to the first bath which molten lead-bismuth has approximately the same lead content as the first bath, continuously removing molten lead-bismuth residual from crystallization from the rst bath of a lower lead content than the rst bath and transferring it to a third bath and continuously repeating the steps mentioned of crystal formation, supply, and withdrawal respectively of the lead-bismuth of a higher and lower lead content in these and successive other baths,

.thereby causing the ilow of lead-bismuth with a gradually increasing lead content in one direction and a ilow of lead-bismuth with a gradually increasing bismuth content in another direction.

10. A process for separating lead and bismuth which comprises crystallizing a lead-bismuth mixture to obtain crystals of lead-bismuth with an increased lead content, separating the crystals, melting the crystals, continuously transferring the melted crystals to another crystallizer or bath of lower temperature than the melted crystals, forming crystals in the other crystallizer, returning part of the molten lead-bismuth from. said other crystallizer to the rst crystallizer, allowing some of the molten contents of said first crystallizer containing a higher bismuth content than the crystals therein to flow therefrom, and continuously removing crystals of lead-bismuth with increased lead content from said other crystallizer, thereby moving the leadbismuth with increased lead in one direction and the lead-bismuth with increasedbismuth in an opposite direction.

1l. A process i'or separating lead and bismuth, which comprises crystallizing a lead-bismuth mixture to obtain crystals of lead-bismuth -with an increased lead content, transferring the crystals from the crystallizer or bath into a melting kettle, melting the crystals, allowing the melted crystals to flow by gravity to another crystallizer, to form crystals there, allowing part of the residual -molten lead-bismuth from said other crystallizer to flow back continuously by gravity again to the rst crystallizer, and allowing some of the molten contents of the first crystallizer containing a higher bismuth-content than the lead-bismuth crystals therein to flow from the iirst crystallizer, and continuously removing crystals of lead-bismuth with increased lead content from said other crystallizer, thereby moving the lead-bismuth with increased lead in one direction and the lead-bismuth with increased bismuth in an opposite direction.

12. A process for separating lead and bismuth which comprises crystallizing a lead-bismuth mixture containing for example approximately 0.15% to .5% of bismuth to obtain crystals of lead-bismuth with an increased lead content, transferring the crystals from the crystallizer into a melting kettle maintained at a higher temperature than said crystallizer, allowing the melted crystals toziiow by gravity to another crystallizer of a lower temperature than said melting kettle and forming crystals in said other crystallizer, allowing a part of the residual molten lead-bismuth from said other crystallizer to flow back continuously by gravity again to the first crystallizer and allowing some of the molten contents of the rst crystallizer contain-v ing a higher bismuth content than the leadbismuth crystals therein to flow from the first crystallizer to a third crystallizer or bath in which crystals are being formed by heat extraction, allowing crystals to form in said third crystallizer and repeating the processes of removing crystals from the first, second and third crystallizers, and transferring crystal and molten products therefrom to other crystallizers and kettles in series, and repeating the steps mentioned with said other kettles and crystallizers, moving the lead-bismuth crystals after melting continuously in one direction and nally obtaining crystals having a bismuth content of .034% or less and moving the molten lead-bismuth mixture through successive other crystallizers and kettles in the opposite direction to obtain a lead-bismuth. mixture containing 2% or more of the bismuth, depending on the number of crystallizers and kettles involved.

13. A process for separating lead and antimony which comprises crystallizing a lead-antimony bath to obtain crystals of lead-antimony with an increased antimony content, continuously removing crystals so formed, supplying thereto a molten lead-antimony mixture of approximately the same lead content as the bath originally contained and removing molten lead-antimony containing a somewhat higher lead content from the said bath, while keeping the crystal and molten mass agitated.

14. A process for treating scrap lead material including storage battery parts containing varying proportions of lead and antimony which comprises smelting said material produc'ng a molten bath of lead-antimony containing about fil 4% antimony and about 96% lead, crystallizing the bath to obtain crystals of lead-antimony with an increased lead content, continuously removing the crystals so formed, supplying thereto more molten lead-antimony mixture and removing molten lead-antimony containing a somewhat lower lead content from the said bath.

l15. A process for treating scrap lead material including storage battery parts containing varying proportions of lead and antimony which comprises smelting said material producing a molten bath of lead-antimony containing about 4% antimony and about 96% lead, crystallizing the bath to obtain crystals of lead-antimony with an increased lead content, transferring crystals so formed continuously to a molten leadantimony bath of a somewhat lower antimony content than the bath from which they came and continuously supplying molten lead-antimony residual from crystallization from the second-mentioned bath to the rst bath, which molten lead-antimony has approximately the same lead content as the first bath, continuously removing molten lead-antimony residual from crystallization from the first bath of a lower lead content than the rst bath and transferring it to a third bath and continuously repeating the steps mentioned of crystal formation, supply, and withdrawal respectively of the lead-antimony of a higher and lower lead content in these and successive other baths, thereby causing the flow of lead-antimony with a gradually increasing lead content in one direction and a ow. of lead-antimony with a gradually increasing antimony content in another direction, until a product containing about 0.4% antimony and about 99.6% lead is obtained at one stage and a product containing about 9% antimony and about 91% lead is obtained at another stage.

16. A process for treating scrap lead material including storage battery parts containing varying proportions of lead and antimony which lcomprises smelting said material producing a molten bath of lead-antimony containing about 4% antimony and about 96% lead, crystallizing the bath to obtain crystals of lead-antimony with an increased lead content, transferring crystals so formed continuously to a-molten leadantimony bath of a somewhat higher lea'd content than the bath from which they came and continuously supplying molten lead-antimony residual from crystallization from the secondmentioned bath, to the first bath which molten lead-antimony has approximately the same lead content as the first bath, continuously removing molten lead-antimony residual from crystallization from the first b ath of a lower lead content than the first bath and transferring it to a third bath and continuously repeating the steps mentioned of crystal formation, supply, and withdrawal respectively of the lead-antimony of a higher and lower lead content in these and successive other baths, thereby causing. the ow of lead-antimony with a gradually increasing lead content in one direction and a flow of leadantimony with a gradually increasing antimony content in another direction, until a product containing about 0.4% antimony and about 99.6% lead is obtained at one stage and a product containing about 9% antimony and about 91% lead is obtained at another stage, preliminarily oxidizing the lead containing about 0.4% antimony to rid it of the antimony and converting the lead so obtained into litharge whereby the lead-antimony compounds and litharge so obtained may be fabricated` into the various parts of storage batteries. l

' ARTHUR E. HALL.

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