SE202000C1

SE202000C1 -

Info

Publication number: SE202000C1
Authority: SE
Publication date: 1965-01-01

Description

Uppfinnare: L T Curnow, P S Randazzo, A J Ratak och T N Bosiljevac jr Prioritet begard Nit den 10 februari 1958 (USA) Denna uppfinning avser ett m.etalhirgiskt forfarande f Or raffinering av bly under vakuum for avlagsnande av zink darifran. Sir-skill avser den ett satsvis genomfOrt forfarande for avskiljning av zink fran bly under vakuum. Inventors: L T Curnow, P S Randazzo, A J Ratak and T N Bosiljevac jr Priority requested Nit February 10, 1958 (USA) This invention relates to a metallurgical process for refining lead under vacuum to remove zinc therefrom. Sir-skill refers to a batch process carried out for separating zinc from lead under vacuum.

Uppfinningen kan tillampas pa alit bly, som innehaller zink, oeh den är sarskilt anvandbar for behandling av det bly, som erhalles fran den kanda silveravskiljningsproceduren, i vilken i My forekommande silver avskiljes darifran som en olkislig zink-silverforening genom tillsats av zink till blyet. Enligt detta kanda forfarande mattas det silverhaltiga blyet vid omkring 482°C med zink och det sa mattade blyet kyles till sin stelningspunkt. Efter avlagsnande av den olosliga zink-silverforeningen, vilken ansamlas som en skorpa pa det smalta blyet, och all den olosliga foreningen, vilken ansamlas pi det kylda blyet, innehaller det aterstaende blyet fortfarande frail 0,5 till 0,6 % zink, vilken maste nedbringas i den efterfoljande raffineringen av blyet till varden under och vanligen val under 0,05 % zink. Den viktigaste fordelen med uppfinningen fir att den astadkomrner ett forfarande for att snabbt fOranga zink frail bly. En annan yiktig fordel med uppfinningen Or att den astadkommer ett forfarande, i vilket den zink, som fumes i fran silver befriat bly, effektivt och mycket hastigt nedbringas till varden under 0,05 % zink. Dessa och andra fordelar framga av efterfoljande mera detaljerade beskrivning av uppfinningen. The invention can be applied to all lead containing zinc, and it is particularly useful for treating the lead obtained from the known silver separation procedure in which the silver present in My is separated therefrom as an alkaline zinc-silver compound by adding zinc to the lead. According to this method, the silvery lead is matted at about 482 ° C with zinc and the so matted lead is cooled to its solidification point. After removal of the insoluble zinc-silver compound which accumulates as a crust on the narrow lead, and all the insoluble compound which accumulates in the cooled lead, the remaining lead still contains from 0.5 to 0.6% zinc, which must is reduced in the subsequent refining of the lead to the value below and usually choice below 0.05% zinc. The main advantage of the invention is that it provides a process for rapidly dispensing zinc free lead. Another important advantage of the invention is that it provides a process in which the zinc contained in silver-free lead is efficiently and very rapidly reduced to the value below 0.05% zinc. These and other advantages will become apparent from the following more detailed description of the invention.

Enligt uppfinningen, vars kannetecken framga air efterfoljande patentansprak, forangas zink frau en smalt massa av bly, som innehaller zink, genom att blymassan Mlles under ett vakuum under cirkulering av den smalta metallen i mass an till och fran -massans yta genom framdrivning av metallen i en bana, vilken omfattar en radiellt utatriktad strom av metall i alla riktningar pd ytan av blymassan frau en zon pi denna yta mot blymassans periferi och med tillracklig hastighet for alstring och uppratthillande av vagor pa blymassans yta, sand kondensering av den frail blymassan forangade zinken. According to the invention, the marks of which appear in the appended patent claims, zinc from a narrow mass of lead containing zinc is vaporized by passing the lead mass under a vacuum while circulating the narrow metal in the mass to and from the surface of the mass by propelling the metal into a path comprising a radially outwardly directed stream of metal in all directions on the surface of the lead mass from a zone on this surface towards the periphery of the lead mass and with sufficient velocity for generating and uplifting waves on the surface of the lead mass, sand condensation of the frail lead mass evaporated zinc.

Den radiella stromningen och alstrandet och uppratthallandet av vagor pa ytan av den smalta blymassan under processen Oro av airgOrande ilkterhallande av hoggradigt zinkavlagsnande frail bly vid tillampning av uppfinningen. Faretradesvis astadkommes den radiella stromningen pa ytan air blymassan genom frigoring av en begransad shorn av metall i riktning uppat vid blymassans yta eller Over eller under denna. Hastigheten lies den frigjorda strommen Or tillracklig for att aistra ()eh uppratthalla vigor pa ytan av massan. FOr uppnaende av basta resultat frigores en begransad shorn i vertikal riktning under och intill blymassans yta. The Radial Flow and the Generation and Maintenance of Waves on the Surface of the Narrow Lead Mass during the Process Concerns of Airgorlant Maintenance of Highly Zinc Depositing Free Lead in the Application of the Invention. Preferably, the radial flow on the surface of the lead mass is effected by releasing a limited horn of metal in the direction upward at the surface of the lead mass or above or below it. The velocity of the released stream is sufficient to maintain () eh maintain vigor on the surface of the mass. To achieve the best results, a limited shorn is released in the vertical direction below and next to the surface of the lead mass.

Graden av zinkavskiljning paverkas ytterligare av arten och utstrackningen av de vagor, som alstras och uppratthallas i den radiellt strommande metallen pd blymassans yta. Utmarkta resultat uppnas salunda nar metallstrommen pa ytan av blymassan Or sadan, att vagor alstras pa storre delen av blymassans 2 yta. Battre resultatuppnas ndr vagor alstras over hela ytan av blymassan. I bada fallen fOrbattras resultaten, nfir vagor alstras, vilka aro °puma och oregelbundna till sin form. En annan fOrbattring av resultaten uppnas, nar amplituden hos atminstone en del av vã-gonna ar sidan, att det alstras brytande vagor, dvs. vagor med sadan amplitud, att hastigheten i riktning framat hos vagkammen skiljer sig frail hastigheten hos huvuddelen-av vagan. Till utseende och form aro dessa bry-. tande vagor likadana som oceanvagor med vita toppar. I allmanhet har det visat sig att nar vagorna ha en amplitud av minst omkring 7,6 cm i narheten av deras utgangspunkt, intraffar brytning av atminstone en del av vá-gonna. The degree of zinc deposition is further affected by the nature and extent of the waves that are generated and maintained in the radially flowing metal on the surface of the lead mass. Excellent results are thus obtained when the metal stream on the surface of the lead mass is such that waves are generated on most of the surface of the lead mass 2. Better results are obtained when waves are generated over the entire surface of the lead mass. In both cases the results are improved, for vaginas are produced, which are aro ° puma and irregular in shape. Another improvement of the results is obtained when the amplitude of at least a part of the wagon is on the side, that refractive waves are generated, i.e. wagons with such an amplitude that the speed in the forward direction of the wagon cam differs from the speed of the main part of the wagon. In appearance and shape aro these bry-. toothed waves similar to ocean waves with white peaks. In general, it has been found that when the wagons have an amplitude of at least about 7.6 cm near their starting point, refraction of at least a part of the wagons occurs.

Foretradesvis anvandes en enda vertikalt uppat framdriven begransad strom, belagen eller intill och parallell med blymassans vertikala amel. Hastigheten i riktning uppat och frigOringsstallet for den begransade stremmen regleras for astadkommande av den onskade vagverkan pa ytan av blymassan. FOretradesvis frigores den begransade strommen pa ett fixerat djup under blymassans yta och med tillracklig hastighet for alstring av vagor med en am.plitud av omkring 7,6-15,2 em. Preferably, a single vertically upwardly driven restricted stream is used, coated or adjacent and parallel to the vertical amel of the lead mass. The velocity in the upward direction and the release point of the limited stream are regulated to achieve the desired ripple effect on the surface of the lead mass. Preferably, the limited current is released at a fixed depth below the surface of the lead mass and at a sufficient velocity to produce waves with an amplitude of about 7.6-15.2 cm.

Nar den radiella ytstrommen enligt uppfinningen erhalles genom frigoring av en uppatriktad begransad strom, upprattas en allman cirkulation av small metall centrerad omkring den begransade strommen. Salunda strommar den smalta flietallen fran den begransade strommen radiellt utht i alla riktningar pa blymassans yta fran den zon vid blymassans yta, som motsvarar den. begransade strommens frigOrings.stalle, och strommar darefter neat och mat till den begransade strommens utgangspunkt, varigenom blymassans yta kontinuerligt fornyas. Nar den foredragna enda vertikalt uppal framdrivna och centralt belagna strOmmen frigOres frail sin begransning under blymassans yta, istadkommes ett turbulent svampliknande svall av flytande small metall ph blymassans yta, som befinner sig Over den begransade strommens frigoringsstallet. Fran svallet strommar metallen radiellt utat i vasentligen lika mangder alla riktningar mot blymassans periferi, och darefter nedht och ink till utgangsstMlet ftir den framdrivna stronunen, vilket stalle foretradesvis Or belaget djupt nere i blymassan. When the radial surface current according to the invention is obtained by releasing an upwardly directed limited current, a general circulation of small metal centered around the limited current is established. Thus, the narrow flute from the limited stream flows radially outward in all directions on the surface of the lead mass from the zone at the surface of the lead mass which corresponds to it. limited release of the stream, and then streams neat and food to the starting point of the limited stream, whereby the surface of the lead mass is continuously renewed. When the preferred single vertically driven and centrally coated stream is released from its confinement below the surface of the lead mass, a turbulent sponge-like surge of liquid small metal ph the surface of the lead mass is located, which is located above the release stable of the limited stream. From the swell, the metal flows radially outwards in substantially equal amounts in all directions towards the periphery of the lead mass, and then down and in to the starting point for the propelled stronun, which is preferably located deep down in the lead mass.

Vid genomforande av forfarandet halles atmosfaren over den smalta blymassan foretradesvis vid ett absolut tryck ej Overstigande omkring 1,0 mm och foretradesvis frau 0,01 till 0,1 mm kvicksilver. Foretradesvis Mlles den sm.alta blymassan Oven vid temperaturer frail 482 till 650°C och allra helst vid omkring 577 till 607°C. Under dessa betingelser och speciellt under de mest foredragna betingelserna undvikes omattlig forangning av bly och processen kan latt genomforas i en apparat av jarn, exempelvis gjutjarn eller stal. In carrying out the process, the atmosphere is preferably passed over the narrow lead mass at an absolute pressure not exceeding about 1.0 mm and preferably from 0.01 to 0.1 mm of mercury. Preferably Mlles the narrow lead mass Above at temperatures from 482 to 650 ° C and most preferably at about 577 to 607 ° C. Under these conditions, and especially under the most preferred conditions, excessive evaporation of lead is avoided and the process can be easily carried out in an apparatus of iron, for example cast iron or steel.

Den fran blymassan forangade zinken kan kondenseras som fast material eller som vatska pa godtyekligt satt. Foretradesvis kondenseras den pa en stor yta intill blymassan. For uppnaende av basta resultat, speciellt i ett satsvis genomfort forfarande, kondenseras zinken som fast metall pa en vattenkyld vidstrackt yta med s.amma utstrackning som blymassans yta och belagen omkring 20-35 cm Over blymassan nar den senare Or stilla och under arbetsvakuum. The zinc evaporated from the lead mass can be condensed as a solid material or as a liquid in any way. Preferably, it is condensed on a large surface adjacent to the lead mass. To obtain the best results, especially in a batch process, the zinc is condensed as a solid metal on a water-cooled wide surface with the same extent as the surface of the lead mass and coated about 20-35 cm above the lead mass when the latter is still and under working vacuum.

Uppfinningen belyses narmare genom den bifogade ritningen och i de lamnade exemplen. Det skall emellertid framhallas att ritningen och exemplen Minims endast for att belysa uppfinningen och att den senare darfor icke skall vara begransad till dessa. ritningen Or den enda figuren en vertikalsektion, som visar en. foredragen apparat ftir genomfOrande av uppfinningen satsvis. The invention is further illustrated by the accompanying drawing and in the illustrated examples. It should be emphasized, however, that the drawing and the examples are only for the purpose of illustrating the invention and that the latter should not be limited thereto. the drawing Or the only figure a vertical section, showing a. preferred apparatus for carrying out the invention batchwise.

Pa ritningen visas en. stalpanna 1 med rund botten i kombination med ett borttagbart forOngnings- oak kon.denseringsaggregat 2. Pannan Or anbragt i en ugn 3, vilken Or forsedd med en eller flera lampliga branslebrannare (ej visade). AggregatetOr ftirsett med en stalskal 4 i form av en. stympad, omvand halvsfar med en tipper): batten, vilken Or anbragt ett tillrackligt stycke under den plana kondensationsytan 5 hos skalenatt, sa- som visas pi ritningen, bilda en vatskelas for skalen, nar den senare befinner sig under arbetsvakuum. Ska.len Or forsedd med en vattenkyld mantel 6 med vatteninlopps- och utloppsledningar 7 och 8. Skalen Or aven forsedd med ett vakuumror 9, vilket leder frau det inre av skalen och är lostagbart forbundet med ledningen 10, vilken i sin tur leder till en. vanlig vakuumpump (ej visad). The drawing shows one. stable boiler 1 with round bottom in combination with a removable evaporating oak condensing unit 2. The boiler Or placed in an oven 3, which Or is equipped with one or more suitable fuel burners (not shown). The unit is provided with a steel shell 4 in the form of a. truncated, turned half-father with a tipper): the bat, which Or placed a sufficient distance below the flat condensation surface 5 of the shell night, as shown in the drawing, forms a water cluster for the shells, when the latter is under working vacuum. The shell Or is provided with a water-cooled jacket 6 with water inlet and outlet lines 7 and 8. The shell Or is also provided with a vacuum tube 9, which leads from the inside of the shell and is releasably connected to the line 10, which in turn leads to a . standard vacuum pump (not shown).

Dessutom. Or skalen forsedd med en propeller 12 fast ph en axel 13, vars nedre del Or belagen i en hylsa 14 med oppna andar. Foretradesvis stracker sig hylsan 14 frail overdelen av vattenmanteln G och nedat atminstone ett styeke, vilket i relation. till det absoluta tryck, som uppratthalles i skalen under processen, Or tillrackligt for astadkommande av en vatskelas vid dess nedre ande. AxeIn 13 Or, sasom cramgOr av ritningen, driven av en motor 15, vilken Over kugghjul 16, 17 och 18 Or forbunden med ett pa axeln 13 anbragt kugghjul 1. In addition. Or the shell is provided with a propeller 12 fixed ph a shaft 13, the lower part of which is coated in a sleeve 14 with open ends. Preferably, the sleeve 14 extends from the upper part of the water jacket G and downwards at least one styeke, which in relation. to the absolute pressure maintained in the shells during the process, is sufficient to produce a liquid shell at its lower spirit. AxleIn 13 Or, as cramgOr of the drawing, driven by a motor 15, which Over gears 16, 17 and 18 Or connected to a gear 1 mounted on the shaft 13.

Propellern 12 Or .anbragt i en. ledning 20, vilken uppbares i sitt lage av band 21, som 3 ph lampligt satt aro fasta vid ytan 5. Den ovre anden av ledningen 20 befinner sig pa lampligt avstand fran ytan 5 for att under genomforande av processen astadkomma utmatning av small metal! fran ledningen vid, over eller under blysmaltans yta och pa samma gang astadkomma ett lampligt avstand mellan smaltans yta och kondensationsytan 5. Sasom. redan anfOrts är avstandet ,mellan kondensationsytan 5 och smaltans yta, nar smaltan Sr stilla men under arbetsvakuum i skalen 4, foretradesvis omkring 20-35 cm och ovre delen av ledningen 20 befinner sig 30-45 em under smaltans yta. Aggregatet 2 Sr for-sett med ett barande stativ 22, vilket uppbares av ugnen 3 med hjalp av ben 23, som aro fasta vid stativet. The propeller 12 Or .placed in a. line 20, which is supported in its layer by belt 21, which 3 ph is suitably attached to the surface 5. The upper end of the line 20 is at a suitable distance from the surface 5 in order to effect small metal discharge during the process! from the conduit at, above or below the surface of the lead malt and at the same time provide a suitable distance between the surface of the melt and the condensation surface 5. As such. already stated, the distance, between the condensation surface 5 and the surface of the melt, when the melt Sr is still but under working vacuum in the shells 4, is preferably about 20-35 cm and the upper part of the conduit 20 is 30-45 cm below the surface of the melt. The unit 2 is provided with a supporting frame 22, which is supported by the oven 3 with the aid of legs 23, which are fixed to the stand.

Vid drift infores en charge av smalt zinkhaltigt My i pannan 1, fran vilken aggregatet 2 liar avlagsnats, och blyet skummas for avlagsnande av slagg. Aggregatet 2 anbringas darefter ger pa ugnen 3 i det lage som visas pa ritningen, roret 9 forbindes ater med roret 10, vattenanslutningarno till ledningarna 7 och 8 asterstallas och vatten cirkuleras genom manteln 6 i tillracklig grad for att halla ytan 5 vid en temperatur som Sr lamplig for kondensering av fast zink pa denna yta. Blyet bringas darefter till arbetstemperaturen genom lamplig eldning av ugnen 3. Darefter reduceras atmosfaren Over metallen i skalen till arbetstryck. Nar skalen evakueras, suges me-tall in i skalen fran pannan, varigenom metallen i den forma bringas aft stiga och i den senare att sjunka imotsvarighet till det reducerade trycket i skalen. FOrlust av vakuum pa grund av lackning av luft in i skalen forhindras emellertid, eftersom mangden till pannan chargerat My Sr sadan, att nivan 30 i pannan befinner sig Over skalens kant 31, nar skalen har evakuerats till arbetstryck. Speciellt vid anvandning av en stor apparat Sr den till pannan 1 chargerade blyvolymen lampligen i huvudsak konstant fran sats till sats, sa att nivan av metallen i skalen under avskiljningen av zink i vane sats är i huvudsak densamma och befinner sig pa Onskat avstand fran kondensationsytan 5 och Ovre de-lea av ledningen 20 i varje sats. Alternativt kunna varierande blymangder chargeras till pannan och anordningar kunna finnas for hojning eller sankning av aggregatet 2 pa ugnen, exempelvis genom anvandning av installbara stod istallet for de fixerade benen 23 for astadkommande av Onskad metallniva i skalen i varje sats. During operation, a charge of narrow zinc-containing My is introduced into the boiler 1, from which the unit 2 has been removed, and the lead is foamed to remove slag. The unit 2 is then applied to the furnace 3 in the layer shown in the drawing, the pipe 9 is reconnected to the pipe 10, the water connections to the pipes 7 and 8 are asterisated and water is circulated through the jacket 6 sufficiently to keep the surface 5 at a temperature suitable for condensing solid zinc on this surface. The lead is then brought to the working temperature by suitable firing of the furnace 3. The atmosphere above the metal in the shells is then reduced to working pressure. When the shells are evacuated, metal is sucked into the shells from the boiler, whereby the metal in the mold is caused to rise and in the latter to sink corresponding to the reduced pressure in the shells. Loss of vacuum due to lacquering of air into the shells is prevented, however, since the amount to the boiler has charged My Sr such that the level 30 in the boiler is above the edge 31 of the shells when the shells have been evacuated to working pressure. Especially when using a large apparatus, the lead volume charged to the boiler 1 is suitably substantially constant from batch to batch, so that the level of the metal in the shells during the separation of zinc in the batch is substantially the same and is at the desired distance from the condensation surface 5. and the upper part of the conduit 20 in each set. Alternatively, varying amounts of lead may be charged to the boiler and devices may be provided for raising or lowering the unit 2 on the furnace, for example by using installable, the fixed legs 23 were provided to provide the desired metal level in the shells of each batch.

Sedan apparaten pa detta satt gjorts i ordning, startas motorn 15, vilken Sr avsedd att kringvrida propellern 12 i den genom pilarna angivna riktningen. Motorn drives med lamp- hg hastighet for att kringvrida propellern 12. med tillracklig hastighet fiir att framdriva den s,malta metallen uppat i ledningen 20 far astadkommande av stromningsmonstret enligt uppfinningen ph smaltans yta. Propellerns rotation fortsattes darefter medan blyet i smaltan Mlles vid arbetstemperaturen och -trycket, tills den avsedda mangden zink forangats Iran blyet och kondenserats som fast metal' ytan 5. Darefter avlagsnas: vakuet 1 skalen 4, riket 9 kopplas fran r5ret 10, vattencirkulationen i manteln 6 avbrytes och aggregatet 2 lyftes fran pannan 1. Det aterstaende blyet avlagsnas fran pannan och den pa ytan 5 kandenserade zinken avlagsnas darifran pa lampligt satt, exempelvis genom vibrering, mejsling eller smaltning. Ovanstaende procedur kan darefter upprepas med en annan blycharge corn skall befrias fran. zink. After the apparatus has been prepared in this way, the engine 15 is started, which is intended to turn the propeller 12 in the direction indicated by the arrows. The motor is driven at lamp speed to rotate the propeller 12. at a sufficient speed to propel the molten metal upwardly in the conduit 20 to produce the flow pattern of the invention on the surface of the melt. The rotation of the propeller was then continued while the lead in the melt was measured at the working temperature and pressure, until the intended amount of zinc was evaporated in the lead and condensed as solid metal surface 5. Then the vacuum in the shells 4, the realm 9 is disconnected from the tube 10, the water circulation in the jacket 6 is interrupted and the unit 2 is lifted from the boiler 1. The remaining lead is removed from the boiler and the zinc condensed on the surface 5 is removed therefrom in an appropriate manner, for example by vibration, chiseling or melting. The above procedure can then be repeated with another lead charge corn to be freed from. zinc.

Ritningen -visar metallstrOmmen pa. ytan °eh i smaltan, nar processen genomfores under forhallanden, vilka leda till uppnaende av de basta resultaten vid tillampning av uppfinningen. Sasom visas pa ritningen framdrives den smalta metallen vertikalt uppat som: en begransad strain i ledningen 20 och med. .sadan hastighet, att nar strommen frigores fran begra.nsning, fortsatter den att strommauppat med tillraeklig hastighet far att bitda det visade turbulenta svallet eller den s. k. svampen av flytande metall pa smaltans yta i zonen ovanfor utloppet fran ledningen 20. Metalten strommar darefter radiellt utat alla riktningar fran svallet till skalens penfeni och med tilräcklig hastighet for astadkommande av ojamna vagor, av vilka de fiesta aro brytande vagor, Over hela ytan av smaltan i skalen. Metallen strommar darefter nedat och mat till ledningens 20 inlopp. The drawing shows the metal current. the surface of the melt when the process is carried out under conditions which lead to the best results in the practice of the invention. As shown in the drawing, the molten metal is propelled vertically upward as: a limited strain in the conduit 20 and so on. at such a speed that when the stream is released from restriction, it continues to flow upstream with sufficient velocity to bite the displayed turbulent swell or the so-called liquid metal sponge on the surface of the melt in the zone above the outlet from the conduit 20. The metal then flows radially outwards. all directions from the swell to the penfeni of the shells and with sufficient speed to produce uneven waves, most of which are breaking waves, over the entire surface of the melt in the shells. The metal then flows down and food to the inlet of the conduit 20.

I en given apparat av den pa ritningen visa-de typen kommer den hastighet i riktning uppat av den smalta metallen i ledningen 20, sam erfordras fiir alstring av den radiella och vagformiga strom.men av metall pa ytan av smaltan i skalen 4 enligt uppfinningen, att paverkas av laget av ledningens 20 utloppsande i farhallande till metallens niva i skalen, nar den senare liar evakuerats till onskat arhetstryck. I en sarskild apparat av donna typ kan den erforderliga hastigheten i riktning uppat f5r ett givet lage av ledningens 20 utloppsande bestammas, sedan det onskade vakuet och metallnivan ha upprattats I skalen 4, genom reglering av motors 15 hastighet, tills de avsedda stromningsfOrhallandena upprattats pa smaltans yta, vilket kan iakttagas genom ett lampligt fluidumtatt fiinster an-, ordnat i skalen, exempelvis ett Mister genoin ytan 5, vilket strb.cker sig genom manteln 6. Den erforderliga hastigheten 1 riktning uppat 4„ i ledningen 20 kan emellertid enkelt bestammas i forvag genom chargering av tillracklig mangd My till pannan 1, sã att blynivan skalen 4' ar i huvudsak densamma, mar den senare icke Sr evakuerad, som nivan kommer att vara nar skalen bar evakuerats till arbetstryck. En spegel fast vid en stang och ett ljus kunna darefter nedsan.kas genom roret 9 efter avlagsnande av rorkroken 32, och motorns 15 hastighet kan darefter regleras, tills den Onskade stroanningen astadkommits pa. ytan av smaltan i skalen, vilket iakttages i spegeln. In a given apparatus of the type shown in the drawing, the velocity in the upward direction of the molten metal in the conduit 20 will be required for the production of the radial and wavy stream of metal on the surface of the melt in the shells 4 according to the invention. to be affected by the layer of the outlet 20 of the conduit in relation to the level of the metal in the shells, when the latter has been evacuated to the desired pressure. In a particular apparatus of this type, the required speed in the upward direction for a given layer of the line outlet 20 can be determined, after the desired vacuum and metal level have been established in the shells 4, by controlling the speed of the motor 15, until the intended flow conditions are established on the melt. surface, which can be observed by a suitable fluid-filled window arranged in the shells, for example a Mister genoin surface 5, which extends through the jacket 6. However, the required speed in the direction upwards 4 in the line 20 can be easily determined in advance. by charging a sufficient amount of My to the boiler 1, so that the lead level of the shells 4 'is essentially the same, but the latter is not evacuated, as the level will be when the shells were evacuated to working pressure. A mirror fixed to a rod and a light can then be lowered through the rudder 9 after removal of the rudder hook 32, and the speed of the motor 15 can then be regulated until the desired flow has been achieved. the surface of the melt in the shells, which is observed in the mirror.

Uppfinningen belyses narmare genom foljande exempel. The invention is further illustrated by the following examples.

Exem.pel 1. 250 ton smalt bly, fran vilket silver avskilts, innehallande 0,5-0,6. % zink chargerades till pannan 1 i den pa ritningen visade apparaten. Chargen upphettades till 593°C, varefter blyet skummades fritt fran slagg. Aggregatet 2 anbringades darefter i det ritningen visade laget och vatten eirkulerades genom manteln 6 i tillräcklig mangd for alt kondensera fast zink pa ytan 5. Aggregatet 2, vilket var relativt kallt flax det anbringades i pannan, sankte metallens temperatur. Sedan metallen Ater upphettats till 593°C, evakuerades skalen 4 och motorn 15 startades for att arbeta med en fixerad, forutbestamd hastighet for att foranga zink fran ytan av .smaltan och kondensera den forangade zinken pa ytan 5 under zinkavskiljningsbehandlingen. Aven under behandlingen halls blyets temperatur vid 588-503°C och trycket hos atmosfaren i skalen Over smaltan h011s vid omkring 0,015 mm kvicksilver. Blyets nivâ i skalen var 45 cm Over Overdelen av ledningen 20 och 35 cm under ytan 5, nar smaltan var stilla och under arbetsvakuum. Example 1. 250 tons of narrow lead, from which silver is separated, containing 0.5-0.6. % zinc was charged to boiler 1 in the apparatus shown in the drawing. The batch was heated to 593 ° C, after which the lead was foamed free from slag. The assembly 2 was then applied in the layer shown in the drawing and water was circulated through the jacket 6 in a sufficient amount to condense solid zinc on the surface 5. The assembly 2, which was relatively cold flax, was applied to the boiler, lowered the temperature of the metal. After the metal Ater was heated to 593 ° C, the shells 4 were evacuated and the engine 15 was started to operate at a fixed, predetermined rate to evaporate zinc from the surface of the melt and condense the evaporated zinc on the surface 5 during the zinc separation treatment. Even during the treatment, the temperature of the lead is kept at 588-503 ° C and the pressure of the atmosphere in the shells above the melt is kept at about 0.015 mm of mercury. The level of lead in the shells was 45 cm Above The upper part of the pipe 20 and 35 cm below the surface 5, when the melt was still and under working vacuum.

Strommen av metall pa smaltans yta vid den fixerade, fOrutbestamda driftshastigheten hos motor. 15 iakttogs, sasom beskrivits ovan, genom nedsankning av en spegel fast vid anden av en stang, ock ett ljus, genom roret 9. Det iakttogs i spegeln all den uppatriktade strommen, som frigjordes fran ledningen 20, astadkom ojamna vagor i den radiellt strOmmande metallen. Vagorna forflyttade sig Over smaltan, bibeh.ollo sin ojamna och turbulenta karaktar och traffade skalens 4 sida. Det iakttogs aven att under loppet av deras radiella rorelse till periferin av smaltan i skalen uppvisade de fiesta vagorna brytande top-par. The flow of metal on the surface of the melt at the fixed, predetermined operating speed of the motor. As described above, by lowering a mirror fixed to the spirit of a rod and a light through the tube 9. All the upward current released from the conduit 20 was observed, causing uneven waves in the radially flowing metal. . The waves moved over the narrow, bibeh.ollo its uneven and turbulent character and hit the 4 sides of the shells. It was also observed that during the course of their radial motion to the periphery of the melt in the shells, most of the vagaries exhibited breaking top pairs.

Zinkavskiljningsbehandlingen fortsattes tills zinkhalten hos. blyet i smaltan reducerats till 0,031 %. Det visade sig att detta uppnaddes pa 3 tinunar. Det visade sig aven att den zink, vilken kondenserades pa. ytan 5, inneholl 6— 10 % bly och hade kondenserats som ett kristalliniskt fast material. Denna blyhaltiga zink an.vandes med framgang for att avskilja silver fran ytterligare portioner av .silverhaltigt bly. The zinc separation treatment was continued until the zinc content of. the lead in the melt was reduced to 0.031%. It turned out that this was achieved in 3 tinuns. It also turned out that the zinc, which was condensed on. surface 5, contained 6-10% lead and had condensed as a crystalline solid. This lead-containing zinc has been used successfully to separate silver from further portions of silver-containing lead.

Exempel 2. 250 kin. frail silver befriat bly innehallande 0,5-0,6 % zink behandlades sasom beskrivits i exempel 1 med anvandning av samma apparat och betingelser, inbegripet samma fixerade, forutbestamda driftshastighet hos motorn 15, som angivits i exempel 1. Det visade sig att zinkhalten hos blyet reducerades till 0,011 % pa 3,5 timmar och att den pa. ytan 5 kondenserade zinken inneholl 5-10 % bly. Example 2. 250 kin. frail silver liberated lead containing 0.5-0.6% zinc was treated as described in Example 1 using the same apparatus and conditions, including the same fixed, predetermined operating speed of the engine 15 set forth in Example 1. It was found that the zinc content of lead was reduced to 0.011% in 3.5 hours and that of. surface 5 condensed zinc contained 5-10% lead.

Exempel 3. 250 ton bly, frail vilket silver avskilts, innehallande 0,5-0,6 % zink behandlades ater sasom beskrivits i exempel 1 i samma apparat och med anvandning av samma temperaturer, tryck och metallniva' i skalen 4. I detta exempel omkastades emellertid motorns 15 rotationsriktning, sa att den smalta metallen framdrevs neat Iran ledningen 20 av propellern 12. Vid detta arrangemang strOmmade metallen i en allmant cirkular bana pa foljande satt. Nedat i ledningen. 20, utat och uppat langs och parallellt med skalens 4 sidor, saint mat over ytan av smaltan i skalen till Owe delen av ledningen 20. Det visade sig att smaltans yta forblev i huvudsak plan och att inga vagor kunde alstras pa denna yta, ens mar motorn arbetade med full hastighet. Det visade sig aven att under dessa betingelser och med anvandning av hogsta motorhastighet minst 12 timmar erfordrades for all reducera zinkhalten hos blyet till 0,04 %. Det visade sig vidare, att zinken som kondenserades som ett kristalliniskt fast material pa ytan 5, inneh011 5-10 % bly. Example 3. 250 tons of lead, frail from which silver was separated, containing 0.5-0.6% zinc were treated again as described in Example 1 in the same apparatus and using the same temperatures, pressures and metal levels in the shells 4. In this example however, the direction of rotation of the engine 15 was reversed so that the molten metal was propelled neatly through the line 20 by the propeller 12. In this arrangement, the metal flowed in a generally circular path as follows. Down in the line. 20, outwards and upwards along and parallel to the 4 sides of the shells, saint mat over the surface of the smalt in the shells to the Owe part of the conduit 20. It turned out that the surface of the smalt remained substantially flat and that no waves could be generated on this surface, even mar the engine was running at full speed. It was also found that under these conditions and using the highest engine speed for at least 12 hours, it was necessary to reduce the zinc content of the lead to 0.04%. It was further found that the zinc condensed as a crystalline solid on the surface 5 contained 5-10% lead.

Claims

Patent claim:

A process for removing zinc from lead, in which a melt of zinc-containing lead is milled under vacuum, while the molten metal is circulated to and from the surface of the melt by means of a circulating means arranged in the melt, the melt also having on its surface a film of metal oxide or slag, characterized in that the narrow metal is circulated in a path which comprises a radially outwardly directed stream of narrow metal in all directions on. the surface of the smalt frail a zone on this surface towards the periphery of the smalt and at a sufficient speed to generate and maintain the surface of the smalt to thereby evaporate the zinc frail smalt.

2. A method according to claim 1, characterized in that the radial current of metal on the surface of the melt is effected by releasing a limited and in the direction of upwardly driven current below a central zone on the surface of the melt, the velocity in the direction upwards of the released current in relation to its release stall below the surface of the melt, it is sufficient to produce and maintain smooth and irregularly shaped waves over the entire surface of the melt. Request Publications: Patents frcin United Kingdom 5911 414.